• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.197-201
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• 2003

액정 디스플레이의 백라이트에 사용되는 냉음극 방전램프(CCFL: Cold Cathode Fluorescent Lamp) 구동 인버터의 설계함에 있어 압전 변압기(Piezoelectric Transformer)를 사용하였으며, 파라미터 선정 및 최적화를 하여 실험을 통해 검증하였다. 적용한 압전 인버터로는 푸시-풀(Push-pull)과 하프-브리지(Half-bridge) 회로이며, 휘도 제어기법으로는 아날로그(Analog)와 버스트(Burst) 방법을 사용하였다. 푸시-풀 인버터의 경우 아날로그 제어방식으로 제어전압 2.5-4.5V에서 출력전류 1-6mA(최소)로 휘도 $0-100\%$ 특성을 보였다. 입출력 효율로 18.6(최소)-90.3(최대)$\%$를 얻었으며, 버스트 제어방식에서는 듀티비 $5-50\%$에서 1-6mA의 제어성능을 보였다. 인버터의 입출력 효율은 13.6(최소)-82.1(최대)$\%$를 얻었다.

• Communications for Statistical Applications and Methods
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• v.15 no.4
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• pp.509-516
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• 2008

We derive the influence function on the coefficient of variation. Empirical influence function and Sample influence function are used to verify the validity of the derived influence function. To show the validity of the influence function, we carry out simulations with random samples from normal distribution $N(20,1^2)$ and $N(20,5^2)$, respectively. The simulation result proves that the derived influence function is very accurate in estimating changes in the coefficient of variation when an observation is deleted.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.356-360
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• 1990

This paper is an application of Modern control Theory to the control of a current-source inverter (CSI) fed Induction Motor Drive System. A Linear Quadratic-Gaussian (LQG) scheme is developed, in which the Kalman Filter is tuned for high robustness by a method due to Doyle and Stein(8). The design is carried out for a sample system and the robustness by analysis and computer simulation.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.05a
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• pp.145-149
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• 2005

This study was carried out to investigate the effect of dietary RVS on the WHC, color stability, and lipid oxidation of Hanwoo (Korean cattle) beef during cold storage after thawing, RVS fed Hanwoo (Korean cattle) beef was more effective in increasing WHC, color stability and delaying lipid oxidation than that without RVS in diet. And 4% RVS fed Hanwoo (Korean cattle) beef showed the greatest effects.

• The Pure and Applied Mathematics
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• v.4 no.1
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• pp.97-104
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• 1997

The large deviations theorem of Cramer is extended to conditional probabilities in the following sense. Consider a random sample of pairs of random vectors and the sample means of each of the pairs. The probability that the first falls outside a certain convex set given that the second is fixed is shown to decrease with the sample size at an exponential rate which depends on the Kullback-Leibler distance between two distributions in an associated exponential familiy of distributions. Examples are given which include a method of computing the Bahadur exact slope for tests of certain composite hypotheses in exponential families.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1285-1292
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• 2009

The effects of the narrowed upside gap on nucleate pool boiling heat transfer in a vertical annulus were investigated experimentally. For the study, a stainless steel tube with a diameter of 25.4 mm and saturated water that kept an atmospheric condition were used. The ratio between the gaps measured at the upper and the lower regions of the annulus ranged from 0.18 to 1. Two different lengths of the modified gap also were investigated. The change in heat transfer due to the modified gap became evident as the gap ratio decreased and the length of the gap increased. As the gap ratio became less than 0.51, a significant decrease in heat transfer was observed compared to the plain annulus. The longer gap size resulted in an additional decrease in heat transfer. The major cause for the tendency was attributed to the formation of lumped bubbles around the upper region of the annulus followed by the increased flow friction between the fluid and the surface around the modified gap.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.2030-2037
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• 2009

In this paper, the study on the allocation of dedicated radio frequency for the radio communication based CBTC system is performed. The dedicated bandwidth for the the private use in railroad is figured out and the allocatable frequency band, which should be investigated hereafter, is proposed. The result of this study provides the basis to present the requirement of dedicated railroad radio frequency and can be used as an important material for the frequency allocation. Furthermore, it is expected that the result can be contributed to the development on railroad radio communication.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.191-205
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• 2003

Effects of the width and location of a flow disturbing circular plate, installed at a vertical tube surface, on nucleate pool boiling heat transfer of water at atmospheric pressure have been investigated experimentally. Through the tests, changes in the degree of intensity of liquid agitation have been analyzed. The plate changes the fluid flow around the tube as well as heat transfer coefficients on the tube surface. It is identified that the plate width changes the rate of the circulating flow whereas its location changes the growth of the active agitating flow. Moreover, the flow chugging was observed at the downside of the plate.

• Communications of Mathematical Education
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• v.13 no.1
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• pp.265-274
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• 2002

이 프로젝트는 수학 수업 중 ‘추론’과 ‘증명’에 관련된 "문제해결과정"에 관심을 가지고, 처음 증명문제를 접하는 독일 7학년 학생들을 대상으로 문제해결능력에 필요한 요인들, 즉, 문제 해결을 위한 수학적 기본지식, 해결된 문제에 대한 인지정도, 논리적 사고 등을 관찰 분석하고 수학교사의 수학에 대한 신념(Beliefs)과 수업 방식이 학생들의 문제해결에 미치는 영향을 조사하는 것에 그 목적을 둔다. 이 프로젝트의 일부의 결과로써, 본 논문에서는 학생들 개개인의 문제해결과정과 그 능력, 그리고 수학에 대한 신념을 서술하고, 수학교사와 학생들의 서로 다른 수학에 대한 신념을 비교 분석한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.749-755
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• 2006

To improve pool boiling heat transfer in an vertical annulus with closed bottoms, the length of an outer tube has been changed from 0.2m to 0.6m. For the test, a heated tube of 19.1mm diameter and water at atmospheric pressure have been used. Annular conditions are made using glass tubes fabricated around the heated tube. The gap size of the annulus is 3.65mm. To elucidate effects of the outer tube length on heat transfer results of the annulus are compared with the data of a single unrestricted tube and the annulus with wider gap size of 6.35mm. Throughout the tests much higher heat transfer coefficients are observed for the annulus of 3.65mm gap size comparing to the other two cases. The change in the outer tube length results in much variation in heat transfer coefficients. Moreover, with shortening the length of outer tube the possibility of the CHF occurrence can be removed.