• Journal of the Korean Mathematical Society
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• v.34 no.3
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• pp.661-672
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• 1997

In this paper we introduce the semidiscrete solution of a single-phase nonlinear Stefan problem We analyze the optimal convergence of the semidiscrete solution in $H^1$ and $H^2$ normed spaces and also we derive the error estimates in $L^2$ normed space.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.159-162
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• 2001

음장의 공간 음향적인 특성에 영향을 받은 음성신호를 원래 신호로 복원하기 위해서 본 논문에서는 MPSV (Minimum Phase Space Volume) 방법 을 도입한다 MPSV 방법 은 신호를 복원하기 위해 원래 신호의 어떠한 사전 정보나 가정을 필요로 하지 않고 그 신호의 비선형적인 동적 특이성만을 이용하는 블라인드 디콘볼루션 (Blind deconvolution) 방법이다. 또한, 이 방법을 이용하여 원래 신호를 복원하는 동시에 음장의 충격응답과 같은 시스템 특성까지도 유추가 가능하다.

• Journal of Astronomy and Space Sciences
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• v.9 no.2
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• pp.154-164
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• 1992

The Mg II lines been extracted from the IUE archival spectra of 32 Cygni to investigate the effect of the atmospheric eclipse. The UV light curve has been reduced from the continuum flux at the center wavelength of 2807.5 ${\AA}$ in the IUE spectra. The equivalent width of the Mg II k absoption line has been measured for each spectra. The results of the light variation and flux tracing of the absorption line at the vicinity of the primary eclipse confirmed the atmospheric eclipse. The atmospheric effect lasted until the phase 0.06 in the absorptin line tracing, while it lasted until the phase 0.02 in the UV light curve, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.4
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• pp.315-320
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• 2008

This paper describes aerodynamic characteristics for the NREL(National Renewable Energy Laboratory) Phase VI rotor using the Fluent which is a commercial flow analysis tool. Aerodynamic analysis results are compared with experimental results by the NREL/NASA Ames wind tunnel tests. For three velocity cases, computed results are compared with experiment results at five spanwise positions. Computed results represented good agreement with the experimental results at low velocity. Otherwise computed results in suction side represents disagreement with the experimental results at high velocity. When interval between wind turbines is 10 times of rotor diameter, CFD research is performed to calculate the wake effect.

• Journal of Power Electronics
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• v.11 no.4
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• pp.401-407
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• 2011

In order to enhance torque density of five-phase permanent magnetic synchronous motor with third harmonic injection for electric vehicles (EVs) applications, optimum seeking method for injection ratio of third harmonic was proposed adopting theoretical derivation and finite element analysis method, under the constraint of same amplitude for current and air-gap flux. By five-dimension space vector decomposition, the mathematic model in two orthogonal space plane, $d_1-q_1$ and $d_3-q_3$, was deduced. And the corresponding dual-plane vector control method was accomplished to independently control fundamental and third harmonic currents in each vector plane. A five-phase PMSM prototype with quasi-trapezoidal flux pattern and its fivephase voltage source inverter were designed. Also, the dual-plane vector control was digitized in a single XC3S1200E FPGA. Simulation and experimental results prove that using the proposed optimum seeking method, the torque density of five-phase PMSM is enhanced by 20%, without any increase of power converter capacity, machine size and iron core saturation.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.44.3-45
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• 2016

In this study, we identify 307 the geosynchronous magnetopause crossing (GMC) using geosynchronous satellite observation data from 1996 to 2010 as well as make an observational test of magnetopause location models using the identified events. For this, we consider three models: Petrinec and Russell (1996), Shue et al. (1998), and Lin et al. (2010). To evaluate the models, we estimate a Probability of Detection (PoD) and a Critical Success Index (CSI) as a function of year. To examine the effect of solar cycle phase, we consider three different time periods: (1) ascending phase (1996-1999), (2) maximum phase (2000-2002), and (3) descending phase (2003-2008). Major results from this study are as follows. First, the PoD values of all models range from 0.6 to 1.0 for the most of years. Second, the PoD values of Lin et al. (2010) are noticeably higher than those of the other models. Third, the CSI values of all models range from 0.3 to 0.6 and those of Shue et al. (1998) are slightly higher than those of the other models. Fourth, the predicted magnetopause radius based on Lin et al.(2010) well match the observed one within one earth radius, while that on Shue et al. (1998) overestimate the observed one by about 2 earth radii. Fifth, the PoD and CSI values of all the models are better for the solar maximum phase than those for the other phases, implying that the models are more optimized for the phase.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.96-102
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• 2014

In this paper, we proposed new dual-rail data encoding that mixed 4-phase handshaking protocol and 2-phase handshaking protocol for asynchronous system design to reduce signal activities and power consumption. The dual-rail data encoding 4-phase handshaking protocol should leat to much signal activities and power consumption by return to space state. Ideally, the dual-rail data encoding 2-phase handshaking protocol should lead to faster circuits and lower power consumption than the dual-rail 4-phase handshaking protocol, but can not designed using standard library. We use a benchmark circuit that contains a multiplier block, an adder block, and latches to evaluate the proposed dual-rail data encoding. The benchmark circuit using the proposed dual-rail data encoding shows an over 35% reduction in power consumption with 4-phase dual-rail data encoding.

• Bulletin of the Korean Space Science Society
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• 2000.10a
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• pp.50-50
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• 2000

No Abstract, See Full Text

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.125-128
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• 2000

In this paper, we introduce an algorithm for identification of the Advanced Mountain Methods parameter. It consists of two phases: Phase I and Phase II. In Phase I, a given data space is divided into subspaces based on the density of the given data. In Phase II, we obtain the AMMs parameter $\omega$ by selecting the minimum of variances of subspaces obtained in Phase I. Numerical examples are presented to show the validity of the proposed method.

• Bulletin of the Korean Space Science Society
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• 2000.04a
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• pp.17-17
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• 2000

No Abstract, See Full Text