• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.33.2-33.2
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• 2019

Horizon Run 5 is the most massive cosmological hydrodynamic simulation ever performed until now. Owing to the large spatial volume ($717{\times}80{\times}80[cMpc/h]^3$) and the high resolution down to 1 kpc, we may study the cosmological effects on star and galaxy formations over a wide range of mass scales from the dwarf to the cluster. We have modified the public available Ramses code to harness the power of the OpenMP parallelism, which is necessary for running simulations in such a huge KISTI supercomputer called Nurion. We have reached z=2.3 from z=200 for a given simulation period of 50 days using 2500 computing nodes of Nurion. During the simulation run, we have saved snapshot data at 97 redshifts and two light cone space data, which will be used later for the study of various research fields in galaxy formation and cosmology. We will close this talk by listing possible research topics that will play a crucial role in helping us take lead in those areas.

• Journal of Astronomy and Space Sciences
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• v.12 no.2
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• pp.234-243
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• 1995

Korea's third rocket, which is currently under development for launch in 1997, is expected to reach as high as 160km and thus, it will provide a good opportunity for the direct measurement of the plasmas in the E-region ionosphere of the Korean peninsula. Langmuir probe techniques, which are the basic tools of the plasma experiment, may yield inaccurate results if they are applied in the conventional form as they are used in the laboratory experiments because of the contamination. In the present paper we study the contamination problem by performing the ground experiments in the vacuum chamber using the contaminated probe. The result show that the contamination effect is reduced when the plasma density is low or when the frequency of the sweep voltage is fast. We propose a modified Langmuir probe based upon our experiments which is suitable for the rocket experiments.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.4
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• pp.9-17
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• 1994

The incremental parsing techniques are essential part of language-based environment which allow incremental construction of programs, as reparsing of modified part of the program alone enhances the system performance. A number of methods and algorithms have been proposed for incremental parsing and for the construction of incremental parsers. The purpose of this paper is to review the earlier incremental parsing algorithms which are too expensive in both time and space, and to present an efficient incremental LR parsing algorithm which is more efficient than the previous ones. In this paper, we generate automatically an extended LR parsing tables which allow the nonterminal symbols as well as terminal symbols for the input, and apply them to our efficient incremental LR parsing algorithm. Using these extended LR parsing tables. we suggest several methods to reduce its memory spaces and parsing steps as well. The algorithms described here were implemented in C language and YACC on a SUN UNIX OS, and were tested with several grammars and strings.

• Journal of Fashion Business
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• v.11 no.6
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• pp.115-124
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• 2007

The cross-section of the polyester filament yarn has been modified to have a variety of shape for aesthetic, added functions and sensitivities, and other purposes. Transparent polyester filament of trilobal cross-section has unique optical properties with high anisotropic reflectivity and transmissivity. The monofilament yarns may be utilized to impart to the fabrics lustrous appearance along with unique color change in case differently dyed yarns are woven together. The color changes of the fabric specimens according to the changes in observation and lighting conditions were analyzed using a CCD camera and an image analysis software. The changes of color/luster of the fabric specimens were measured and analyzed based on RGB, $L^*a^*b^*,\;L^*C^*h,$ and the color distribution within a three-dimensional color space.

• Publications of The Korean Astronomical Society
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• v.25 no.4
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• pp.155-165
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• 2010

In this study, we investigate the changes in the equatorial lodge degrees and polar distance degrees of determinative stars in the ancient Chinese archives. Confirmed is the fact that the coordinate values of those determinative stars defined in B.C. 104 had been used until the 8th century but were modified by the observations of Li Chunfeng (李淳風) in the early 7th century and Yixing (一行) in 723 A.D. The results of this study are compared with those in History of Chinese Astronomical Observations of Pan Nai. By applying the results of comtemporary astrodynamical calculations, their reliability is checked, and the corrected catalogues of Shi Shi (石氏) and Yixing are provided. The positional accuracy of those observations is estimated to be one degree.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.482-483
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• 2012

In this paper, the operation of current-fed quasi-Z-source inverter (QZSI) with buck-boost function, improved reliability, and regeneration capability is analyzed. The modified space modulation technique for controlling effectively both shoot-through time and zero voltage time is suggested. The simulation result is carried out in order to verify the performance of proposed technique.

• Kyungpook Mathematical Journal
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• v.48 no.1
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• pp.133-142
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• 2008

In this paper, we prove two strong convergence theorems for asymptotically nonexpansive mappings in Hibert spaces by hybrid methods. Our results extend and improve the recent ones announced by Nakajo, Takahashi [K. Nakajo, W. Takahashi, Strong convergence theorems for nonexpansive mappings and nonexpansive semigroups, J. Math. Anal. Appl. 279 (2003) 372-379], Kim, Xu [T. H. Kim, H. K. Xu, Strong convergence of modified mann iterations for asymptotically nonexpansive mappings and semigroups, Nonlinear Anal. 64 (2006) 1140-1152], Martinez-Yanes, Xu [C. Martinez-Yanes, H. K. Xu, Strong convergence of the CQ method for fixed point iteration processes, Nonlinear Anal. 64 (2006) 2400-2411] and some others.

• Bulletin of the Korean Chemical Society
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• v.15 no.3
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• pp.241-245
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• 1994

A method has been developed to estimate the kinetic energy release originating from the reverse critical energy in unimolecular ion dissociation. Contribution from the excess energy was estimated by RRKM theory, the statistical adiabatic model and the modified phase space calculation. This was subtracted from the experimental kinetic energy release distribution (KERD) via deconvolution. The present method has been applied to the KERDs in $H_2$, loss from $C_6H_6^+$ and HF loss from ${CH_2CF_2}^+$. In the present formalism, not only the energy in the reaction coordinate but also the energy in some transitional vibrational degrees of freedom at the transition state is thought to contribute to the experimental kinetic energy release. Details of the methods for treating the transitional modes are found not to be critical to the final outcome. For a reaction with small excess energy and large reverse critical energy. KERD is shown to be mainly governed by the reverse critical energy.

• KSBB Journal
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• v.22 no.5
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• pp.336-340
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• 2007

Supercritical carbon dioxide was used to remove coffee odors. The odor removal efficiency was tested with coffee drink prepared by the espresso extraction method. Five typical odors in coffee were analyzed with GC and these odors in deodorized coffee were compared to those in control. Supercritical carbon dioxide extraction conditions were optimized as 350 bar and 70$^{\circ}C$ because the solvating power of supercritical fluid is depend on the density which is determined by temperature and pressure. A modified head space method was applied to collect coffee odors in coffee drink prepared by the espresso extraction method. Odors generated in coffee drink made with deodorized coffee powder were reduced by 73% in total mass of typical five coffee odors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1617-1624
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• 2006

This paper presents system modeling, modified space vector PWM implementation and design of a closed loop controller of the Z-source inverter which consists of L and C components and shoot-through zero vectors for DGS. Zero vector periods of SVPWM utilized to boost DC-link voltage instead of conventional DC/DC converter and transformer. Only two shoot-through vut(nn are used for DC link voltage control during one switching period without loss of non-zero vectors. Discrete time sliding mode controller, robust servomechanism controller are designed to realize fast and no-overshoot current response and a steady state voltage error. Simulation results are shows the effectiveness of the proposed algorithm.