Author name code: kim-kap-sung ADS astronomy entries on 2022-09-14 =author:"Kim, Kap-Sung" OR =author:"Kim, Kap Sung" ------------------------------------------------------------------------ Title: Optimal Lunar Point Return Orbit Design and Analysis via a Numerical Three-Step Approach Authors: Song, Yongjun; Song, Young-Joo; Kim, Kap-Sung; Jin, Ho; Lee, Donghun Bibcode: 2020IJASS..21.1129S Altcode: 2020IJASS.tmp...46S Herein, the characteristics of the Moon-to-Earth (M-E) trajectory satisfying the point return orbit (PRO) conditions are analyzed and optimized. A numerical three-step approach is proposed to serve as a useful tool to generate trajectory while preparing for real-world missions. To formulate the given problem, each step properly adapts different equations of motion with design parameters suitable to each step's primary objective. Three- and N-body equations of motion are used as a basis, and PRO is constrained by the parking orbit at the Moon and Earth re-entry corridor associated with the re-entry position. Consequently, the major trans-Earth-injection (TEI) maneuver condition at the Moon is optimized together with the right ascension of the ascending node and the argument of the latitude. Moreover, the TEI maneuver magnitude with its execution date and required time of flight is optimized to form PRO. Adopting this three-step approach, the effect of the Moon's relative motion with respect to the Earth to form the optimal TEI condition is clearly analyzed. In addition, direct insight on the TEI condition is obtained by expressing the M-E rotating frame, which is expected to save time and effort while generating initial guesses for TEI conditions. Title: A New Method for Coronal Magnetic Field Reconstruction Authors: Yi, Sibaek; Choe, Gwang-Son; Cho, Kyung-Suk; Kim, Kap-Sung Bibcode: 2017SPD....4810604Y Altcode: A precise way of coronal magnetic field reconstruction (extrapolation) is an indispensable tool for understanding of various solar activities. A variety of reconstruction codes have been developed so far and are available to researchers nowadays, but they more or less bear this and that shortcoming. In this paper, a new efficient method for coronal magnetic field reconstruction is presented. The method imposes only the normal components of magnetic field and current density at the bottom boundary to avoid the overspecification of the reconstruction problem, and employs vector potentials to guarantee the divergence-freeness. In our method, the normal component of current density is imposed, not by adjusting the tangential components of A, but by adjusting its normal component. This allows us to avoid a possible numerical instability that on and off arises in codes using A. In real reconstruction problems, the information for the lateral and top boundaries is absent. The arbitrariness of the boundary conditions imposed there as well as various preprocessing brings about the diversity of resulting solutions. We impose the source surface condition at the top boundary to accommodate flux imbalance, which always shows up in magnetograms. To enhance the convergence rate, we equip our code with a gradient-method type accelerator. Our code is tested on two analytical force-free solutions. When the solution is given only at the bottom boundary, our result surpasses competitors in most figures of merits devised by Schrijver et al. (2006). We have also applied our code to a real active region NOAA 11974, in which two M-class flares and a halo CME took place. The EUV observation shows a sudden appearance of an erupting loop before the first flare. Our numerical solutions show that two entwining flux tubes exist before the flare and their shackling is released after the CME with one of them opened up. We suggest that the erupting loop is created by magnetic reconnection between two entwining flux tubes and later appears in the coronagraph as the major constituent of the observed CME. Title: Heating of an Erupting Prominence Associated with a Solar Coronal Mass Ejection on 2012 January 27 Authors: Lee, Jin-Yi; Raymond, John C.; Reeves, Katharine K.; Moon, Yong-Jae; Kim, Kap-Sung Bibcode: 2017ApJ...844....3L Altcode: 2017arXiv170609116L We investigate the heating of an erupting prominence and loops associated with a coronal mass ejection and X-class flare. The prominence is seen as absorption in EUV at the beginning of its eruption. Later, the prominence changes to emission, which indicates heating of the erupting plasma. We find the densities of the erupting prominence using the absorption properties of hydrogen and helium in different passbands. We estimate the temperatures and densities of the erupting prominence and loops seen as emission features using the differential emission measure method, which uses both EUV and X-ray observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the X-ray Telescope on board Hinode. We consider synthetic spectra using both photospheric and coronal abundances in these calculations. We verify the methods for the estimation of temperatures and densities for the erupting plasmas. Then, we estimate the thermal, kinetic, radiative loss, thermal conduction, and heating energies of the erupting prominence and loops. We find that the heating of the erupting prominence and loop occurs strongly at early times in the eruption. This event shows a writhing motion of the erupting prominence, which may indicate a hot flux rope heated by thermal energy release during magnetic reconnection. Title: Laboratory measurements of light polarization on samples targeted for the lunar regolith Authors: Kim, Il-Hoon; Sung, Suk Kyung; Kim, Sungsoo S.; Jeong, Minsup; Sim, Chae Kyung; Baek, Kilho; Kim, Kap-Sung; Choi, Young-Jun Bibcode: 2017AdSpR..59.1629K Altcode: We carried out multi-band (B, V, and R bands) polarimetric measurements of several soil samples targeted for the lunar regolith (JSC-1A, Fe2 O3 , SiC, and JSC-1Mars). Our laboratory experiments are intended to provide some constraints to the theoretical and numerical studies of the light scattering off the particulate surface of airless bodies in the solar system. Among our samples, the lunar soil simulant JSC-1A has the closest αmax to the typically observed value on the lunar surface, ∼100 ° , where αmax is the phase angle at which the polarization has the maximum value. In the other samples, αmax is higher than 120 ° or significantly wavelength dependent. The empirical relationship between the grain size, maximum polarization and albedo for the lunar regolith overestimates the actual grain sizes of some of our samples by a factor of up to ∼6. The measured polarization degrees and albedos of the JSC-1A sample are similar to the typical observed values of the lunar maria. We also find that the wavelength dependence of both polarization degree and albedo is larger for smaller-grain samples. Title: Physical properties of coronal mass ejection plasma associated with erupting prominences as seen emission or absorption features in EUV and X-rays Authors: Lee, Jin-Yi; Raymond, John C.; Reeves, Kathy; Moon, Yong-Jae; Kim, Kap-Sung Bibcode: 2016SPD....4740201L Altcode: We investigate the physical properties (temperature, density, mass, and energy) of coronal mass ejection plasmas observed by the Atmospheric Imaging Assembly on Solar Dynamics Observatory and X-ray Telescope on Hinode. The prominences are seen as absorption features in EUV at the beginning of their eruptions. Later the prominences change to emission features during eruptions, which indicates the heating of the erupting plasma. We find the temperatures and densities of the erupting prominences using absorption properties of hydrogen and helium in different passbands. We estimate the temperatures and densities of the erupting plasma in emission features using differential emission measure method, which uses both EUV and X-ray observations applying various spectra using photospheric and coronal abundances. We verify and discuss the methods for the estimation of temperatures and densities for erupting plasmas. Lastly, we discuss the heating of the coronal mass ejection plasmas. Title: Statistical analysis of supersonic downflows in sunspot penumbrae. Authors: Kim, Hyunnam; Lagg, Andreas; Solanki, Sami K.; Narayan, Gautam; van Noort, Michiel; Kim, Kap-Sung Bibcode: 2015IAUGA..2254868K Altcode: Supersonic downflow patches was found in the outer edge of sunspot penumbra. These patches are believed to be the return channels of the Evershed flow. There was previous study to investigate their structure in detail using Hinode SOT/SP observations (M. van Noort et al. 2013) but their data sample was only two sunspots. To make general description it needs to check more sunspot data sample.We selected 242 downflow patches of 16 sunspots using Hinode SOT/SP observations from 2006 to 2012. Height-dependent maps of atmospheric parameters of these downflows was produced by using HeLix which was height dependent LTE inversion code of Stokes profiles.Statistical analysis of magnetic field strength, inclination angle of field line, temperature and line-of-sight velocity are presented. The recovered atmospheric data tell us that downflow patches have different physical signatures comparing normal penumbra properties. Furthermore, our results of three height-dependent layer support that heating process should occur on the downflow patches in the middle of layer. Title: How Well Can a Footpoint Tracking Method Estimate the Magnetic Helicity Influx during Flux Emergence? Authors: Choe, Gwangson; Kim, Sunjung; Kim, Kap-Sung; No, Jincheol Bibcode: 2015IAUGA..2254507C Altcode: As shown by Démoulin and Berger (2003), the magnetic helicity flux through the solar surface into the solar atmosphere can be exactly calculated if we can trace the motion of footpoints with infinite temporal and spatial resolutions. When there is a magnetic flux transport across the solar surface, the horizontal velocity of footpoints becomes infinite at the polarity inversion line, although the surface integral yielding the helicity flux does not diverge. In practical application, a finite temporal and spatial resolution causes an underestimate of the magnetic helicity flux when a magnetic flux emerges from below the surface, because there is an observational blackout area near a polarity inversion line whether it is pre-existing or newly formed. In this paper, we consider emergence of simple magnetic flux ropes and calculate the supremum of the magnitude of the helicity influx that can be estimated from footpoint tracking. The results depend on the ratio of the resolvable length scale and the flux rope diameter. For a Gold-Hoyle flux rope, in which all field lines are uniformly twisted, the observationally estimated helicity influx would be about 90% of the real influx when the flux rope diameter is one hundred times the spatial resolution (for a large flux rope), and about 45% when it is ten times (for a small flux rope). For Lundquist flux ropes, the errors incurred by observational estimation are smaller than the case of the Gold-Hoyle flux rope, but could be as large as 30% of the real influx. Our calculation suggests that the error in the helicity influx estimate is at least half of the real influx or even larger when small scale magnetic structures (less than 10,000 km) emerge into the solar atmosphere. Title: Mass and Energy of Erupting Solar Plasma Observed with the X-Ray Telescope on Hinode Authors: Lee, Jin-Yi; Raymond, John C.; Reeves, Katharine K.; Moon, Yong-Jae; Kim, Kap-Sung Bibcode: 2015ApJ...798..106L Altcode: 2014arXiv1411.2229L We investigate seven eruptive plasma observations by Hinode/XRT. Their corresponding EUV and/or white light coronal mass ejection features are visible in some events. Five events are observed in several passbands in X-rays, which allows for the determination of the eruptive plasma temperature using a filter ratio method. We find that the isothermal temperatures vary from 1.6 to 10 MK. These temperatures are an average weighted toward higher temperature plasma. We determine the mass constraints of eruptive plasmas by assuming simplified geometrical structures of the plasma with isothermal plasma temperatures. This method provides an upper limit to the masses of the observed eruptive plasmas in X-ray passbands since any clumping causes the overestimation of the mass. For the other two events, we assume the temperatures are at the maximum temperature of the X-ray Telescope (XRT) temperature response function, which gives a lower limit of the masses. We find that the masses in XRT, ~3 × 1013-5 × 1014 g, are smaller in their upper limit than the total masses obtained by LASCO, ~1 × 1015 g. In addition, we estimate the radiative loss, thermal conduction, thermal, and kinetic energies of the eruptive plasma in X-rays. For four events, we find that the thermal conduction timescales are much shorter than the duration of eruption. This result implies that additional heating during the eruption may be required to explain the plasma observations in X-rays for the four events. Title: Systematic Effects on the Genus Topology of the Large-scale Structure of the Universe Authors: Kim, Young-Rae; Choi, Yun-Young; Kim, Sungsoo S.; Kim, Kap-Sung; Lee, Jeong-Eun; Shin, Jihye; Kim, Minbae Bibcode: 2014ApJS..212...22K Altcode: 2014arXiv1404.6314K The large-scale structure of the universe is a useful cosmological probe of primordial non-Gaussianity and the expansion history of the universe because its topology does not change with time in the linear regime in the standard paradigm of structure formation. However, when the topology of iso-density contour surfaces is measured from observational data, many systematic effects are introduced due to the finite size of pixels used to define the density field, nonlinear gravitational evolution, redshift space distortion, shot noise (discrete sampling), and bias in the distribution of the density field tracers. We study the various systematic effects on the genus curve to a great accuracy by using the Horizon Run 2 simulation of a ΛCDM cosmology. We numerically measure the genus curve from the gravitationally evolved matter and dark matter halo density fields. It is found that all the non-Gaussian deviations due to systematic effects can be modeled by using a few low-order Hermite polynomials from H 0 to H 4. We compare our results with analytic theories whenever possible, and find many new terms in the Hermite series that are making significant contributions to the non-Gaussian deviations. In particular, it is found that the amplitude drop of the genus curve due to the nonlinear gravitational evolution can be accurately modeled by two terms, H 0 and H 2, with both coefficients proportional to \sigma _0^2, the mean-square density fluctuation. Title: Temperature and mass estimation of erupting plasma associated with coronal mass ejections observed by Hinode/XRT and SDO/AIA Authors: Lee, Jin-Yi; Raymond, John C.; Reeves, Kathy; Moon, Yong-Jae; Kim, Kap-Sung Bibcode: 2014AAS...22421836L Altcode: We investigate the temperature and mass of erupting plasma observed in X-ray and EUV, which are associated with coronal mass ejections (CMEs) and X-class flares. Hinode/XRT observed the erupting hot plasma in a few passbands, which allows us to determine the temperature of the plasma using a filter ratio method. SDO/AIA observed the erupting plasma in EUV passbands. We estimate the temperatures and emission measures of the erupting plasma in EUV using a differential emission measure method. One of these observations shows an eruptive plasma with a loop-like structure in X-ray and EUV. The temperature of the erupting plasma in X-ray is about 13 MK by the filter ratio method. The estimated mass of this erupting plasma in X-ray is similar to that in EUV. A couple of events are associated with the eruptions of prominences as absorption features in EUV in addition to hot plasma eruption. One event shows that the absorption features change to emission features at the beginning of their eruptions in all EUV wavelengths of SDO/AIA. By estimating the temperature and mass of the erupting plasmas, we discuss the heating of the plasmas associated with coronal mass ejections in the low corona. Title: Coronal Thick Target Hard X-Ray Emissions and Radio Emissions Authors: Lee, Jeongwoo; Lim, Daye; Choe, G. S.; Kim, Kap-Sung; Jang, Minhwan Bibcode: 2013ApJ...769L..11L Altcode: 2013arXiv1304.5517L A distinctive class of hard X-ray (HXR) sources located in the corona was recently found, which implies that the collisionally thick target model (CTTM) applies even to the corona. We investigated whether this idea can be independently verified by microwave radiations which have been known as the best companion to HXRs. This study is conducted on the GOES M2.3 class flare which occurred on 2002 September 9 and was observed by the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the Owens Valley Solar Array. Interpreting the observed energy-dependent variation of HXR source size under the CTTM, the coronal density should be as high as 5 × 1011 cm-3 over a distance of up to 12''. To explain the cutoff feature of the microwave spectrum at 3 GHz, however, we require a density no higher than 1 × 1011 cm-3. Additional constraints must be placed on the temperature and magnetic field of the coronal source in order to reproduce the microwave spectrum as a whole. First, a spectral feature called the Razin suppression requires a magnetic field in a range of 250-350 G along with high viewing angles around 75°. Second, to avoid excess fluxes at high frequencies due to the free-free emission that was not observed, we need a high temperature >=2 × 107 K. These two microwave spectral features, Razin suppression and free-free emissions, become more significant at regions of high thermal plasma density and are essential for validating and determining additional parameters of the coronal HXR sources. Title: Characteristic dimension of electromagnetic ion cyclotron wave activity in the magnetosphere Authors: Lee, Jeongwoo; Min, Kyungguk; Kim, Kap-Sung Bibcode: 2013JGRA..118.1651L Altcode: In this paper, we estimate the size of coherent activity of electromagnetic ion cyclotron (EMIC) waves using the multi-spacecraft observations made during the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission. We calculate the cross-correlations between EMIC wave powers measured by different THEMIS spacecraft, plot them over the separation distances between pairs of observing spacecraft, and determine the 1/e folding distance of the correlations as the characteristic dimension of the coherent wave activity. The characteristic radius in the direction transverse to the local magnetic field is found to lie in rather a wide range of 1500-8600 km varying from the AM to PM sectors and also from hydrogen to helium bands. However, the characteristic dimensions normalized by either gyroradius or wavelength fall into narrower ranges almost independent of the emission band and event location. Specifically, the coherent dimension is found to be 10-16 times gyroradius of 100 keV protons and 2-3 times local wavelength. The former may give a useful scale for the source dimension, and the latter suggests that the EMIC wave activity maintains coherency only up to a couple of wavelengths. Title: The Challenge of the Largest Structures in the Universe to Cosmology Authors: Park, Changbom; Choi, Yun-Young; Kim, Juhan; Gott, J. Richard, III; Kim, Sungsoo S.; Kim, Kap-Sung Bibcode: 2012ApJ...759L...7P Altcode: 2012arXiv1209.5659P Large galaxy redshift surveys have long been used to constrain cosmological models and structure formation scenarios. In particular, the largest structures discovered observationally are thought to carry critical information on the amplitude of large-scale density fluctuations or homogeneity of the universe, and have often challenged the standard cosmological framework. The Sloan Great Wall (SGW) recently found in the Sloan Digital Sky Survey (SDSS) region casts doubt on the concordance cosmological model with a cosmological constant (i.e., the flat ΛCDM model). Here we show that the existence of the SGW is perfectly consistent with the ΛCDM model, a result that only our very large cosmological N-body simulation (the Horizon Run 2, HR2) could supply. In addition, we report on the discovery of a void complex in the SDSS much larger than the SGW, and show that such size of the largest void is also predicted in the ΛCDM paradigm. Our results demonstrate that an initially homogeneous isotropic universe with primordial Gaussian random phase density fluctuations growing in accordance with the general relativity can explain the richness and size of the observed large-scale structures in the SDSS. Using the HR2 simulation we predict that a future galaxy redshift survey about four times deeper or with 3 mag fainter limit than the SDSS should reveal a largest structure of bright galaxies about twice as big as the SGW. Title: Three-dimensional simulations of the lunar sodium exosphere and its tail Authors: Lee, Dong-Wook; Kim, Sang J.; Lee, Dong-Hun; Jin, Ho; Kim, Kap-Sung Bibcode: 2011JGRA..116.7213L Altcode: The brightness distributions of the lunar sodium exosphere reported by Flynn and Mendillo (1993) and the receding velocities of the lunar sodium tail observed by Mierkiewicz et al. (2006) are reproduced by 3-D Monte Carlo simulations. We consider the effects of two spatially different sodium sources simultaneously: dayside source with the dependency of solar zenith angle and an isotropic source due to micrometeoroid impact. In the simulations, the following effects are taken into account: (1) the gravity of the Moon, the Earth, and the Sun with the orbital motion of the Moon; (2) photoionizations, solar radiation pressure, and returns to the lunar surface; and (3) the shadows of the Earth and Moon. The sodium brightness observed by Flynn and Mendillo (1993) is successfully modeled, from which the most probable source ratio between the isotropic and dayside sources is estimated to be 70%∼80%: 30%∼20%, respectively. The best coma model provides an initial velocity of 2.0 km/s with a narrow Doppler width of 0.2 km/s and a total production rate of 0.7 × 1022/s. On the basis of the best 3-D lunar coma model, we also simulate the receding velocity distribution of lunar sodium tail, and we find satisfactory models for high receding velocity and its wide dispersion observed by Mierkiewicz et al. (2006) considering the effect of variable solar radiation pressure and appropriate ionization times. Title: Prediction of Communication Outage Period between Satellite and Earth station Due to Sun Interference Authors: Song, Yongjun; Kim, Kap-Sung; Jin, Ho; Lee, Byoung-Sun Bibcode: 2010JASS...27...31S Altcode: Geostationary satellites are located at an altitude of approximately 35,786km above the equator, and revolve in the same angular velocity as earth. Geostationary satellites can therefore, communicate with a ground earth station at all times. However, geostationary satellites also experience communication failure time, twice a year, closely one upon the other in spring and autumn quarters. The communication errors occur when ground station-satellite-the Sun are aligned closely, which occurs during spring and fall equinoxes. At such times, thermal noise emitted from the Sun's surface hits the rear side of the satellite and flows directly into the earth station antenna. This is called solar interference. Studies on duration calculation methods and prediction results of a solar interference phenomenon were implemented by many scientists (Vuong & Forsey 1983, Mohamadi & Lyon 1988, Lin & Yang 1989) abroad, and also by Lee et al. (1991) in Korea. To calculate the time of solar interference, information on precise position of the Sun and earth station antenna systems is necessary. Previous researches used the formula of Van Flandern (Van Flandern & Pulkkinen 1979) when calculating the Sun's position, but it has position error of about 1 arcmin. Using the precise ephemeris DE406, which published by NASA/JPL and the earth ellipsoid model, the study calculated the precise positioning of the Sun as causing error within 10 arcsec. For the verification of the calculation, we used TU media ground station located in Seongsu-dong and the MBSAT satellite operated by TU media. Title: The system design of TRIO cinema Mission Authors: Jin, Ho; Seon, Jongho; Kim, Khan-Hyuk; Lee, Dong-Hun; Kim, Kap-Sung; Lin, Robert; Parks, George; Tindall, Craig; Horbury, T. S.; Larson, Davin; Sample, John Bibcode: 2010cosp...38.1923J Altcode: 2010cosp.meet.1923J TRIO (Triplet Ionospheric Observatory) CINEMA ( Cubesat for Ion, Neutral, Electron, MAg-netic fields) is a space science mission with three identical cubesats. The main scientific objec-tives are a multi-observation of ionospheric ENA (Energetic Neutral Atom) imaging, ionospheric signature of suprathermal electrons and ions and complementary measurements of magnetic fields for particle data. For this, Main payloads consist of a suprathermal electron, ion, neutral (STEIN) instrument and a 3-axis magnetometer of magnetoresistive sensors. The CINEMA is a 3-unit CubeSat, which translates to a 10 cm x 10 cm x 30 cm in volume and no more than four kilograms in mass. An attitude control system (ACS) uses torque coils, a sun sensor and the magnetometers and spin CINEMA spcaecraft 4 rpm with the spin axis perpendicular to the ecliptic plane. CINEMA will be placed into a high inclination low earth orbit that crosses the auroral zone and cusp. Three institutes are collaborating to develop CINEMA cubesats: i) two cubesats by Kyung Hee University (KHU) under their World Class University (WCU) program, ii) one cubesat by UC Berkeley under the NSF support, and iii) three magnetometers are provide by Imperial College, respectively. In this paper, we describe the system design and their performance of TR IO cinema mission. TRIO cinema's development of miniature in-strument and spacecraft spinning operation will play an important role for future nanosatellite space missions Title: Estimate of Coronal Magnetic Field Strength Using Plasmoid Acceleration Measurement Authors: Jang, Min-Hwan; Choe, G. S.; Lee, K. S.; Moon, Y. J.; Kim, Kap-Sung Bibcode: 2009JKAS...42..175J Altcode: No abstract at ADS Title: Synthetic high-resolution near-IR spectra of the Sun for planetary data reductions made from ATMOS/Spacelab-3 and Atlas-3 data Authors: Seo, Haingja; Kim, Sang J.; Hwang, Sungwon; Jung, Aeran; Kim, Ji Hyun; Kim, Joo Hyeon; Kim, Kap-Sung; Lee, Jinny; Jang, Minhwan Bibcode: 2007Icar..192..287S Altcode: We have constructed synthetic solar spectra for the 2302-4800 cm -1 (2.08-4.34 μm) range, a spectral range where planetary objects mainly emit reflected sunlight, using ATMOS (Atmospheric Trace Molecule Spectroscopy)/Spacelab-3 and Atlas-3 spectra, of which resolution is 0.01 cm -1. We adopted Voigt line profiles for the modeling of line shapes based on an atlas of line identifications compiled by Geller [Geller, M., 1992. Key to Identification of Solar Features. A High-Resolution Atlas of the Infrared Spectrum of the Sun and the Earth Atmosphere from Space. NASA Reference Publ. 1224, vol. III. NASA, Washington, DC, pp. 1-22], who derived solar line positions and intensities from contaminated high-resolution solar spectra obtained by ATMOS/Spacelab-3. Because the ATMOS spectra in these wavelength ranges are compromised by absorption lines of molecules existing in Earth's high-altitude atmosphere and in the compartment of the spacecraft, the direct use of these high-resolution solar spectra has been inconvenient for the data reductions of planetary spectra. We compared the synthetic solar spectra with the ATMOS spectra, and obtained satisfactory fits for the majority of the solar lines with the exception of abnormal lines, which do not fit with Voigt line profiles. From the model fits, we were able to determine Voigt line parameters for the majority of solar lines; and we made a list of the abnormal lines. We also constructed telluric-line-free solar spectra by manually eliminating telluric lines from the ATMOS spectra and filling the gaps with adjacent continua. These synthetic solar spectra will be useful to eliminate solar continua from spectra of planetary objects to extract their own intrinsic spectral features. Title: Two-Step Reconnections in a C3.3 Flare and Its Preflare Activity Observed by Hinode XRT Authors: Kim, Sujin; Moon, Young-Jae; Kim, Khan-Hyuk; Kim, Yeon-Han; Sakurai, Takashi; Chae, Jongchul; Kim, Kap-Sung Bibcode: 2007PASJ...59S.831K Altcode: We investigated the evolution of a C3.3 impulsive flare and its preflare activity, which occurred in NOAA Active Region 10923 on 2006 November 12, using Hinode X-Ray Telescope (XRT) data. For an extensive investigation, we also used GOES X-ray flux, TRACE 171Å, and SOHO MDI data. Examining the time-series of the XRT and TRACE images, we can identify the following evolutionary sequences: (1) There were three bundles of loops along the sheared polarity inversion line forming a sigmoidal structure during the preflare phase. (2) Preflare brightening occurred between two upper-loop bundles, and they consequently formed one larger bundle. (3) The main flare occurred near the location where this new loop bundle and the third bundle met together. (4) As a result, a single stacked loop structure was formed. This morphological evolution of the X-ray loops is quite consistent with a tether-cutting model involving a single-bipole explosion. Our result shows that the preflare and the main flare in this event are a two-step reconnection process, which strongly suggests that the preflare activity plays an important role in triggering the main flare. Title: Component-Based Development of Observational Software for KASI Solar Imaging Spectrograph Authors: Choi, Seong-Hwan; Kim, Yeon-Han; Moon, Yong-Jae; Choi, Kyung-Seok; Park, Young-Deuk; Jang, Bi-Ho; Kim, Su-Jin; Kim, Kap-Sung Bibcode: 2005JKAS...38..463C Altcode: No abstract at ADS Title: A Study of Flare-associated X-Ray Plasma Ejections. I. Association with Coronal Mass Ejections Authors: Kim, Yeon-Han; Moon, Y. -J.; Cho, K. -S.; Kim, Kap-Sung; Park, Y. D. Bibcode: 2005ApJ...622.1240K Altcode: We have made a comprehensive statistical study of the relationship between flare-associated X-ray plasma ejections and coronal mass ejections (CMEs). For this we considered all flare-mode data in Yohkoh SXT observations from 1999 April to 2001 March and then selected 279 limb flares seen at longitudes greater than 60°. For these events, we identified whether there were associated X-ray plasma ejections or not. We found that about half (137/279) of the flares have X-ray plasma ejections, and we present a comprehensive list of these with their event times and speeds. We then determined whether there was an association between the flares with plasma ejections and CMEs detected by the Solar and Heliospheric Observatory LASCO instrument, on the basis of temporal and spatial proximity. It is found that about 69% (95/137) of the X-ray plasma ejections are associated with CMEs and that about 84% (119/142) of the events without plasma ejections do not have related CMEs. The associations are found to increase with flare strength and duration. We find that X-ray plasma ejections occur nearly simultaneously with the hard X-ray flare peak, supporting the idea that the X-ray plasma ejections are tightly associated with the flaring process. When the CMEs are extrapolated into the Yohkoh field of view for 43 selected, well-observed events, it is found that about 80% of the CMEs preceded X-ray plasma ejections, by approximately 20 minutes on average. Our results show that X-ray plasma ejections usually do not represent the early signature of a CME's leading edge but are closely associated with CMEs. Title: High-Speed x-ray Jets Associated with the 18 June 1999 Limb Flares Authors: Kim, Yeon-Han; Kim, Kap-Sung; Jang, Minhwan Bibcode: 2001SoPh..203..371K Altcode: Peculiar high-speed X-ray jets associated with the 18 June 1999 limb flares have directly been observed with the soft X-ray Telescope (SXT) aboard Yohkoh. The jets have a much shorter lifetime (within 200 s) and a much larger velocity (∼ 1700 km s−1) than the previously reported jets. Judged from their large velocity, the kinetic energy of the jets is approximately one order of magnitude larger than the thermal energy content, which is far different from the jets previously reported by other researchers. Here we present the preliminary results and discuss the particular features of the jets. Title: New Digital H-alpha Observation by Solar Flare Telescope at BOAO Authors: Lee, C. -W.; Moon, Y. -J.; Park, Y. D.; Jang, B. -H.; Kim, Kap-Sung Bibcode: 2001JKAS...34..111L Altcode: Recently, we have set up a new digital CCD camera system, MicroMax YHS-1300 manufactured by Roper Scientific for H-alpha observation by Solar Flare Telescope at Bohyunsan Optical Astronomical Observatory. It has a 12 bit dynamic range, a pixel number of 1300x1030, a thermoelectric cooler, and an electric shutter. Its readout speed is about 3 frames per second and the dark current is about 0.05 e-/p/s at -10 C degree. We have made a system performance test by confirming the system linearity, system gain, and system noise that its specification requires. We have also developed a data acquisition software which connects a digital camera controller to a PC and acquires H-alpha images via Microsoft C++ 6.0 under Windows 98. Comparisons of high quality H-alpha images of AR 9169 and AR 9283 obtained from SOFT with the corresponding images from Learmonth Solar Observatory in Australia confirm that our H-alpha digital observational system is performed properly. Finally, we present a set of H-alpha images taken from a two ribbon flare occurred in AR 9283. Title: Prediction of 23rd Solar Cycle Using the Statistical and Precursor Method Authors: Jang, Se Jin; Kim, Kap-Sung Bibcode: 1999PKAS...14...91J Altcode: We have made intensive calculations on the maximum relative sunspot number and the date of solar maximum of 23rd solar cycle, by using the statistical and precursor methods to predict solar activity cycle. According to our results of solar data processing by statistical method, solar maximum comes at between February and July of 2000 year and at that time, the smoothed sunspot number will reach to 114.3 122.8. while precursor method gives rather dispersed value of 118 171 maximum sunspot number. It is found that prediction by statistical method using smoothed relative sunspot number is more accurate than by any method to use any data of 10.7cm radio fluxes and geomagnetic aa, Ap indexes, from the full analysis of solar cycle pattern of these data. In fact, current ascending pattern of 23rd solar cycle supports positively our predicted values. Predicted results by precursor method for Apavg , aa_{31-36} indexes show similar values to those by statistical method. Therefore, these indexes can be used as new precursors for the prediction of 23rd or next solar cycle. Title: The Prediction of Solar Activity for Solar Maximum Authors: Lee, Jinny; Jang, Se Jin; Kim, Yeon Han; Kim, Kap-Sung Bibcode: 1999PKAS...14..103L Altcode: We have investigated the solar activity variation with period shorter than 1000 days, through Fourier transformation of solar cycle 21 and 22 data. And real time predictions of the flare maximum intensity have been made by multilinear regression method to allow the use of multivariate vectors of sunspot groups or active region characteristics. In addition, we have examined the evolution of magnetic field and current density in active regions at times before and after flare occurrence, to check short term variability of solar activity. According to our results of calculation, solar activity changes with periods of 27.1, 28.0, 52.1, 156.3, 333.3 days for solar cycle 21 and of 26.5, 27.1, 28.9, 54.1, 154, 176.7, 384.6 days for solar cycle 22. Periodic components of about 27, 28, 53, 155 days are found simultaneously at all of two solar cycles. Finally, from our intensive analysis of solar activity data for three different terms of 1977 ~ 1982, 1975 ~ 1998, and 1978 ~ 1982, we find out that our predictions coincide with observations at hit rate of 76%, 63%, 59% for all class flare and of 86%, 27%, 55% for M class flare respectively. Title: Polarization-Magnetic Field Calibration Curve Authors: Kim, Kap-Sung Bibcode: 1997PKAS...12....1K Altcode: We have obtained theoretical calibration curves to convert the amount of polarization into the strength of magnetic field, by a numerical calculation of radiation transfer for the polarized spectral line of FeI 6303A. In our calculation, three kinds of atmospheric models (VAL-C, penumbra, umbra) have been used to make a proper calibration for an active region composed of quiet, penumbral and umbral areas. It was found that firstly, the results of our calculation depend highly on a kind of atmospheric model rather than on any other input parameters used in a model. Secondly, observed line profile showed in solar spectrum atlas proved to be very similar to the calculated profiles obtained by using a penumbral model. Finally, another method except this calibration curve should be developed to estimate correctly the distribution of magnetic field in solar active region from the observation of polarized spectral line. Title: The Prediction of Flare Production Using Solar Activity Data Authors: Lee, Jinny; Kim, Kap-Sung Bibcode: 1996PKAS...11..263L Altcode: We have intensively carried out numerical calculations on flare predictions from the solar activity data for photospheric sunspots, chromospheric flare and plages, coronal X-ray intensities and 2800MHz radio fluxes, by using multilinear regression method. Intensities of solar flares for the next day have been predicted from the solar data between 1977-1982 and 1993-1996. Firstly, we have calculated flare predictions with the multilinear regression method, by using separate solar data in growth and decay phase of sunspot area and magnetic field strength from the whole data on solar activities. Secondly, the same operations as above have been made for the remaining data after removal of the data with large deviation from the mean calculated by the above prediction method. We have reached a conclusion that average hit ratio of correct predictions to total predictions of flares with class of M5 over has been as high as 70% for the first case and that of correct prediction number to total observation number has been shown as 61%. Title: Structure of the Photospheric Vector Magnetic Fields Authors: Cho, Kyung Seok; Kim, Kap-Sung Bibcode: 1995PKAS...10...91C Altcode: We have intensively examined the structure of photospheric magnetic fields obtained from the calculation of the polarized radiation transfer for the model atmosphere. To determine more reliable magnetic field in the photospheric region composed of umbra, penumbra and quiet area, we have calculated the polarized radiative transfer for a magnetically sensitive spectral line, FeI 6302.5A, using out composite model representing three kinds of the atmospheric area distinguished by the pixel value of the Stokes I image over the region. Polarization data of the full Stokes parameters, used in this paper had been obtained from the vector magnetograph on Solar Flare Telescope of National Astronomical at Mitaka(MTK) in Japan. According to our investigation on the active region in the photosphere, it has been found that the large current density(=> 8x10^2 A/km^2) and shear angle(=> 85 deg) should be distributed along the magnetic neutral line. To be compared with the results of MTK, our results in transverse magnetic field strength and direction are similar with those of MTK, however our longitudinal field strength at the center of the spot is somewhat (~1000 Gauss) larger than MTK. Title: Development of a Computer Program for Astronomical Image Data Processing by Observational Equipment in Astronomical Observatory of Kyung Hee University Authors: Kim, Kap-Sung Bibcode: 1995PKAS...10..135K Altcode: We have developed a graphic software for image processing of astronomical data obtained by observational equipment in Astronomical Observatory of Kyung Hee University. The essential hardware for running our computer program is simply composed of a PC with the graphic card to handle 256 colors and the color graphic monitor, including CCD camera system. Our software has been programmed in WINDOWS to provide good environments for users, by using various techniques of image processing on astronomical image data recorded in FITS format by KHCCD program(Jin and Kim,1994) with a compressional mode. We are convinced that our results will be a fundamental and useful technique in the construction of data processing system and can be effectively used in any other observatories, as well as in data processing system of Kyung Hee University. Title: Development of System Software for Astronomical Observations by CCD Photometric System in Astronomical Observatory of Kyung Hee University Authors: Jin, Ho; Kim, Kap-Sung Bibcode: 1994PKAS....9..101J Altcode: We have investigated intensively an optical telescope with 76cm diameter and CCD camera system in astronomical observatory of Kyung Hee university, in order to maximize instrumental functions of our observational equipments and to construct a more reliable photometric system. And computer softwares AUTO DOME, KH CCD and KH PHO for astronomical image observations and their automatic photometries with high accuracy have been made for observers to use our observational system conveniently and efficiently. Throughout careful examinations of these programs, it has been proved that the observing time by our program is shorter than that by manual operations, so that, fast and accurate observations can be executed with ease. For open cluster NGC 7063 observed with S/N value of 350 or more by KH PHO, we have found the magnitude measurements of 11 object stars would show 0.007 magnitude difference, comparing with magnitude data from IRAF/APPHOT. From automatic photometry of eclipsing binary, AB And observed by our software, total 220 data points with good quality have been acquired during 8 hours and so we could make a better light curve than that obtained from any observational results by domestic photoelectric photometry system. Title: Numerical Method for the Astronomical Almanac and Orbit Calculations Authors: Kim, Kap-Sung Bibcode: 1993PKAS....8..137K Altcode: We have calculated the astronomical almanac 1994 and simulated the trajectory of a satellite orbit considering all perturbative forces with various initial conditions. In this work, Gauss Jackson multistep integration method has been used to calculate our basic equation of motion with high numerical accuracy. It has been found that our results agree well with the Astronomical Almanac Data distributed by JPL of NASA and the orbit simulations have been carried out with fast speed, stability and excellent round-off error accumulation, comparing with other numerical methods. In order to be carried out our works on almanac and orbit calculations easily by anyone who uses a personal computer, we have made a computer program on graphical user interface to provide various menus for detail works selected by a mouse. Title: Graphic Library for Astronomical Image Processing Authors: Kim, Kap-Sung; Hong, Seung Soo Bibcode: 1992PKAS....7..261K Altcode: No abstract at ADS Title: Doppler Analysis of Spectral Line Profiles Authors: Kim, Kap-Sung; Sim, Kyung Jin; Park, Young Deuk; Yun, Hong Sik Bibcode: 1991PKAS....6...16K Altcode: No abstract at ADS Title: Graphic Library for Astronomical Calculations Authors: Kim, Kap-Sung; Minn, Young Key Bibcode: 1990PKAS....5...95K Altcode: No abstract at ADS Title: Atomic Spectra of Non-Thermal Equilibrium Atmospheres Authors: Kim, Kap-Sung Bibcode: 1990PKAS....5...40K Altcode: No abstract at ADS Title: Fine Structure of Quiescent Prominences Authors: Kim, Kap-Sung Bibcode: 1990JKAS...23...31K Altcode: Fine structures of a quiescent prominence are studied by analyzing high resolution H alpha filtergrams and H alpha line spectra observed observed at the Hida Observatory of Kyoto University. We have found two kinds of downward motions in the prominence. One of them is a movement with a constant acceleration below the solar gravity(=1/4g_s) and the other with an uniform velocity(=16Km/s). The average life time and the size of prominence knots are estimated to be about 7 minutes and 4000Km, respectively. Spatial and brightness distribution of knots are also presented in this paper. With the analytical solutions derived from magnetostatic equilibrium in the prominence, we have examined the filamentary structure based on the Kippenhahn-Schluter model. Sag angles of the magnetic fields supporting the prominence matter are predicted from the observed density profile. Title: Hydrogen Emission Spectra of Quiescent Prominences Authors: Kim, Kap-Sung Bibcode: 1990JKAS...23...71K Altcode: Theoretical calculations of the combined radiative transfer and statistical equilibrium equation including the charge-particle conservations have been carried out for a multilevel hydrogen atom in quiescent prominences. Cool and dense models show the steep changes of population and radiation field in the vicinity of the surface, while these physical quantities remain unchanged for models with temperature of 7,300K, regardless of total densities. Ionization rate of hydrogen atom related with metallic line formation varies in considerable amounts from the surface to the center of model prominences cooler than 6,300K. However, such cool models cannot release enough hydrogen line emissions to explain observed intensities. Prominence models with a temperature higher than 8,000K can yield the centrally reversed Lyman line profiles confirmed by satellite EUV observations. We find that quiescent prominence with a density between 2x10^11 and 10^12 cm^-3 should be in temperature range between 6,300K and 8,300K, in order to explain consistently observed H alpha, beta line emissions and n_p/n_1 ratio. Title: Emitting region of sodium lines in solar prominences Authors: Kim, Kap-Sung Bibcode: 1988SoPh..114...47K Altcode: We have calculated the emission spectra of hydrogen and sodium atoms in the cool part of prominence models which satisfy simultaneously the constraints of radiative transfer, statistical equilibrium and charge-particle conservations. Title: Emitting region of sodium lines in solar prominences Authors: Kim, Kap-Sung Bibcode: 1987SoPh..114...47K Altcode: The emission spectra of hydrogen and sodium atoms in the cool part of prominence models which satisfy simultaneously the constraints of radiative transfer, statistical equilibrium and charge-particle conservations have been calculated. In the considered range of the model parameters, emission strengths of H-alpha and NaI D lines increase with temperature and total number density. Low-pressure models raise the ionization rate significantly but yield very weak NaI D line intensities, since these model prominences contain small amounts of free electrons and sodium atoms which have a deep relation with the formation of sodium lines. It is found that sodium D lines should be emitted in the high pressure region of prominences, and that their intensities are difficult to attain in the cool core of any model prominence with a temperature as low as 4000 K. In order to explain consistently the spectral emissions of H-alpha and NaI D lines observed in quiescent prominences, a total number density higher than 4 x 10 to the 11th/cu cm and a temperature over 5000 K are required, at least in the cool part of prominences. Title: A Small-Scale Energy Release Observed on the Limb - Part One - the Broadened Components of d3 Emission Lines Authors: Kawaguchi, Ichiro; Kim, Kap-Sung; Nakai, Yoshihiro Bibcode: 1986SoPh..106...47K Altcode: The D3 emission lines observed on the emerging flux loops and mound prominences above the limb were locally found to consist of two components, i.e., the main and the broadened components. A number of Doppler shifted emission lines, separated distinctly from the main body of the emission lines were also detected, which we call the separated components. On the sequential spectrograms, the lifetimes of these broadened and separated components were obtained and their histograms were made.