• Journal of the Korean Magnetics Society
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• v.5 no.4
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• pp.261-268
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• 1995

In order to investigate the origin of the asymmetric magnetization reversal effect, we studied the variation of magnetic hysteresis loops with the alloy composition in amorphous ferromagnetic alloy ribbons of ${(Fe_{1-x}Co_{x})}_{75}Si_{10}B_{15}$ system annealed at $380^{\circ}C$ for 16 hours in a zero field condition. The asymmetric magnetization reversal effect developed more strongly in amorphous ribbons having two metallic components than in ribbons having a single metallic component. The effect developed more strongly in ribbons showing a smaller value of the saturation mag¬netostriction. The development of the asymmetric magnetization reversal effect was affected by the ratio of two metallic components as well as the magnitude of the saturation magnetostriction.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.196-203
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• 1993

Emulsions were prepared with the inversion emulsification method which adopted the agent-in-oil method-dissolving the mixed surfactants composed of the glycerin monostearate, polyoxyethylene(100) monostearate, and polyoxyethylene(20) sorbitan monostearate into mixtures of liquid paraffin and beeswax, and adding the aqueous solution of propylene glycol, gradually-and then their phases and viscosities behaviors in the emulsifying process were investigated. The fine and homogeneous o/w emulsions were formed in the HLB region (HLB 10.1~12.3), showing liquid crystalline phase and white gel phase in the emulsifying process. The phase inversion steps in the emulsifying process appeared as follows, i.e., oil continuous phase${\rightarrow}$liquid crystalline phase${\rightarrow}$white gel phase${\rightarrow}$o/w emulsion. Shear rate-shear stress curves of the prepared emulsions had the yield values which pointed out the existence of inner structure between emulsion particles, and the hysteresis loop which showed that the inner structure wasbroken irreversibly by the shear. The area of hystersis loop, an index of breakdown of inner structure, was increased with the decreasing of the HLB value of emulsifier, Shear time-shear stress curves showed the time dependence of plastic viscosity, and the relaxation time in time thinning behavior(${\lambda}$) indicated that the stability of emulsions prepared with the inversion emulsification method was decreased with the increasing of HLB values of emulsifier and was higher than that of emulsions prepared by homomixer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.2
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• pp.190-198
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• 1995

Many industrial servo amplifiers employ power transister as output device. Thyristor converters are not adopted to drive servo motor, although thyristor is superior to power TR in power rating, noise immunity, price, and size. The reason is, thyristor has no ability of self turn - off. Here in this paper line commutation, in which thyristor is turned off naturally since cathode voltage is higher than anode as time goes by, is employed to turn on thyristor with a delicate sequence. We developed thyristor servo amplifier which does not cause any damage on thyristor because it is designed to prevent triggering the two SCRs in the same arm simultaneously. And it was made clearly how to trigger SCR without any power line shorting and also harmonic analysis is carried out with the aid of FFT analyzer and proved that it can be used even severe reactive load. The designed circuit operated as a good DC amplifier in conventinal servomotor and the results can be use as a position control system application.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.181-186
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• 2006

An imaging method of seismic sources using time-reversal wave propagation is presented. The method is based on the time-reversal invariance and the spatial reciprocity of the wave equation. Time-reversal wave propagation has been used to image anomalous features of a midium in medical imaging, non destructive testing and waveform tomography. Seismogram is the record whose energy is propagated from the seismic source. If time-reversed seismogram propagates back into the medium, seismic energy is concentrated at the origin time of the event and at the source location. In this work, a staggered-grid finite-difference method of the elastic wave equation is parallelized for 3-D wave propagation simulation. With numerical experiments, we show that the time-reversal imaging will enable us to explore the spatio-temporal history of complex earthquake.

• The Journal of Korean Philosophical History
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• no.53
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• pp.131-163
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• 2017

We were already thrown into the modern by the Japanese before reflecting the relevance of modernization and acceptance, and the value of the modern was postponed. The late period of Chosun, people sank into a state of torpor and traditional culture and ideology has caused people to have a negative perception of modern times.Modern times, however, are defined in the relative concept of tradition and modernity in the history of modern times. In order to understand the modern era and its origin, it is necessary to look squarely at the face of modernity. Failure of modern times is a failure of traditional succession.So, if we analyze the causes of the failure of the traditional heritage, why can't we see some of the reasons why we perceive it as a failure? In this thesis, it seeks to understand the diverse views of the traditional elites of the journal and the newspaper, which are published in the traditional education of the journal, and are looking at a variety of views. Moreover, we should seek to explore the traditional elements of the new tradition by discussing the aspects of the educational problems caused by the cause of the accidental break and the educational problems caused by its results.

• The Korean Journal of Financial Management
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• v.18 no.1
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• pp.107-128
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• 2001

금융기관이 직면하는 시장위험관리와 관련된 연구는 이자율과 주식가격 변동위험, 또는 환율과 이자율 변동위험만을 고려한 자산배분모델이므로 그 모형의 정교성에도 불구하고 국제금융기관의 시장위험관리 모형으로 이용하기에는 부족한 점이 있다. 시장위험인 VAR를 측정하는 방법 중 포트폴리오 VAR 측정방법인 델타-노말 방법을 응용하여 금융기관이 시장위험을 종합적으로 관리하는 한편, 기대수익을 최대화시키는 자산-부채의 최적배분에 대한 모형을 유도할 수 있다. 본 논문은 포트폴리오 접근법을 이용하여 금융기관의 시장위험을 종합적으로 관리할 수 있는 모형을 개발하는 동시에 미국, 일본, 영국, 독일의 주요 금융자산의 가격변동자료를 바탕으로 실증적 분석을 시도하였다. 이론적 모형과 관련하여 국제금융기관이 시장위험을 통제하는 한편 목표수익을 달성하는데 필요한 $m_1$ 종류의 국내자산과 부채의 규모, $m_2$ 종류의 외화자산과 부채의 규모를 동시적으로 결정할 수 있는 모델을 개발하였다. 이 모형은 금융기관의 위험포지션과 목표수익이 변동함에 따라 재구성되어야 할 국내외 자산과 부채의 포트폴리오에 대한 종류와 규모를 구체적으로 파악할 수 있게 한다. 실증분석을 위해 미국에 본점을 두고 미국, 일본, 영국, 독일에서 영업활동을 하는 국제금융기관이 16개의 국내외 금융자산을 이용 가능한 것으로 가정하였다. 1995년 1월부터 1999년 6월까지 이들 금융자산의 월별자료와 각 국 통화의 대 U.S. 달러 환율을 이용하여 목표이익 10,000천 달러를 실현하는 한편 이자율과 환율 위험을 최소화시키는 자산, 부채의 적정구성에 관한 결과를 제시하였다.구의 성과로는 특정 투자자 집단이 주가의 움직임에 따라 매매를 하는 수동적 전략의 의미보다는 적극적으로 주가를 움직이는 주체로서 외국인투자자와 일부 기관투자자의 존재를 확인할 수 있었다는 점이며, 주가 움직임에 따른 개인투자자와 일부 기관 투자자의 수동적 매매 스타일과 기관투자자 사이의 투자스타일의 이질성을 통계적으로 확인할 수 있었다는 데에 있다.남아 각국과 우리나라간에는 주가변동에 시차가 없는 것으로 나타났다. 그러나 각국간 표준시차 및 거래소 거래시간을 고려하면 미국, 영국, 독일의 경우에도 그 시차는 1일이내이거나 거의 시차가 없는 것으로 판단된다. 발견되어 선물의 선도효과가 지배적임을 발견하였다.적 일정하게 하는 소비행동을 목표로 삼고 소비와 투자에 대한 의사결정을 내리고 있음이 실증분석을 통하여 밝혀졌다. 투자자들은 무위험 자산과 위험성 자산을 동시에 고려하여 포트폴리오를 구성하는 투자활동을 행동에 옮기고 있다.서, Loser포트폴리오를 매수보유하는 반전거래전략이 Winner포트폴리오를 매수보유하는 계속거래전략보다 적합한 전략임을 알 수 있었다. 다섯째, Loser포트폴리오와 Winner포트폴리오를 각각 투자대상종목으로써 매수보유한 반전거래전략과 계속거래 전략에 대한 유용성을 비교검증한 Loser포트폴리오와 Winner포트폴리오 각각의 1개월 평균초과수익률에 의하면, 반전거래전략의 Loser포트폴리오가 계속거래전략의 Winner포트폴리오보다 약 5배정도의 높은 1개월 평균초과수익률을 실현하였고, 반전거래전략의 유용성을 충분히 발휘하기 위하여 장단기의 투자기간을 설정할 경우에 6개월에서 36개월로 이동함에 따라 6개월부터 24개월까지는 초과수익률이 상승하지만,

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.917-926
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• 1999

In this paper, the recording device for measuring the magnetic field waveforms associated with the cloud lightning discharges was made by the loop-type magnetic field sensor, and the measuring system of a distance between lightning stroke point and observatory site was proposed. The parameters including the time interval of superimposed pulses, zero-to-zero crossing time and the percentage depth of the dip for the positive and the negative magnetic field waveforms were statistically analyzed as a function of the distance between the lightning discharge point and the observatory site. The results could be summarized as follows; Several superimposed pulses were observed at the initial front part of the magnetic field waveform produced by cloud lightning discharges, and the mean time interval between superimposed pulses was about $4\mu\textrm{s}$. Also, the bipolar characteristic appeared significantly and the percentage depth of the dip was about 57~65%. It was known that the zero-to-zero crossing time of the electromagnetic fields is gradually decreased as a distance between lightning discharge point and observatory site is increased.

• The Korean Journal of Financial Management
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• v.21 no.2
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• pp.125-151
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• 2004

This study tests the price discovery from US Treasury bond markets to Korean bond markets using the daily returns of Korean bond data (CD, 3-year T-note, 5-year T-note, 5-year corporate note) and US treasury bond markets (3-month T-bill, 5-year T-note 10-year T-bond) from July 1, 1998 to December 31, 2003. For further research, we divide full data into two sub-samples on the basis of the start-up of bond valuation system in Korean bond market July 1, 2000, employing uni-variate AR(1)-GARCH(1,1)-M model. The main results are as follows. First the volatility spillover effects from US Treasury bond markets (3-month T-bill, 5-year T-note, 10-year T-bond) to Korean Treasury and Corporate bond markets (CD, 3-year T-note, 5-year T-note, 5-year corporate note) are significantly found at 1% confidence level. Second, the price discovery function from US bond markets to Korean bond markets in the sub-data of the pre-bond valuation system exists much stronger and more persistent than those of the post-bond valuation system. In particular, the role of 10-year T-bond compared with 3-month T-bill and 5-year T-note is outstanding. We imply these findings result from the international capital market integration which is accelerated by the broad opening of Korean capital market after 1997 Korean currency crisis and the development of telecommunication skill. In addition, these results are meaningful for bond investors who are in charge of capital asset pricing valuation, risk management, and international portfolio management.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.248-249
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• 2007

본 연구에서는 능동 구동형 유기 발광 소자(AMOLED)에 쓰이는 수소화된 비정질 실리콘(a-Si:H)의 전류 안정성(stability)을 개선하기 위한 새로운 구동방법(driving method)을 제안한다. 제안된 방식은 한 프레임 시간 중 특정 시간동안 비정질 실리콘 박막 트랜지스터(Thin Film Transistor, TFT)에 음의 화상데이터전압을 인가함으로써 열화(degradation)를 억제한다. 비정질 실리콘 박막트랜지스터의 열화를 회복하기 위한 음의 화상데이터의 진폭은 실제 이미지를 표현하는 이전에 인가한 양의 화상데이터에 의해 결정된다. 본 연구에서 제안된 구동방식을 시뮬레이션을 통하여 화소 회로의 동작을 검증하였고, 이를 통해 비정질 실리콘 박막 트랜지스터의 열화가 억제되는 것과 화면의 균일성(screen uniformity) 개선하고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.85-98
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• 1993

A method of analysis for the material and geometric nonlinear analysis of planar prestressed concrete cable-stayed bridges including the time-dependent effects due to load history, creep, shrinkage, aging of concrete and relaxation of prestress is described. The analysis procedure, based on the finite element method, is capable of predicting the response of these structures through elastic, cracking, inelastic and ultimate ranges. The nonlinear formulation for the description of motion is based on the updated Lagrangian approach. To account for the material nonlinearity, nonlinear stress-strain relationship and cracking of concrete, nonlinear stress-strain relationships of reinforcing steel, prestressing steel, and cable, including load reversal are given. Results from a numerical examples on ultimate analyses of cable-stayed bridges are presented to illustrate the analysis method.