• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.107-115
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• 1997

비성형 동력학계로 모델링된 부유수송체의 동적응답을 조사하고 그 운동의 안정성을 해석하였다. 종동요 모우드의 고유주파수가 횡동요 모우드의 고유주파수의 두배가 되는, 즉, 2:1 내부공진 혹은 자기계수공진인 조건하에서, 이부유수송체는 한 운동 모우드의 직접가진에 의해 간접가진된 다른 모우드가 대진폭 응답을 보일 수 있음을 밝혔다. 또항, 종동요 모우드의 감쇠력은 비교적 넓은 범위의 운동에 대해 선형적임에 반해, 횡동요 모우드의 감쇠력은 점성의 영향이 대단히 커서 비선형성이 대단히 강한 것으로 알려져 왔다. 이 문제를 수학적으로 모델링하기 위하여, 종동요 모우드의 운동방정식에는 선형및 제곱형의 합의 형태인 감쇠력 모형을 사용하였다. 다중척도법을 사용하여 이 두가지 운동 모우드의 주기적 응답및 그의 안정성에 미치는 제곱형 비선형 횡동요 감쇠력의 영향을 밝혔다. 조우주기가 횡동요 모우드의 고유주기와 근사한 경우에 대하여 이 비선형계의 응답을 구하고 주파수-응답 곡선으로 나타내었다.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.517-524
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• 1995

This study was conducted to investigate the characteristics of the road alignment, correlations among evaluation factors of the alingment, and the relationships between the evaluation factors and terrain factors for the forest road of five National Forest Offices. The results were as follows : 1. The elongation coefficients(${\eta}$) of forest road in Kangnung and Wonju National Forest Office were ranged 0.3~0.5, and those of Andong, Namwon, and Kongju National Forest Offices were ranged 0.2~0.3 in straight line of 100m, 200m, and 300m. 2. Three different types of plane alignment were identified for Kangnung and Wonju National Forest Offices, Namwon and Kongju National Forest Offices, Andong National Forest Office. However, longitudinal alignment for five National Forest Offices tended to be similar conditions. 3. Low correlation coefficients were calculated in the relation between elongation coefficients(${\eta}$) and evaluation factors of plane alignment(curve length ratio(%), sum of inverse number of each curve radius(m/km), and sum of each intersection angle($^{\circ}/km$)) for three straight lines. On the contrary, high correlation coefficients were obtained among the relations of curve length ratio(%), sum of inverse number of each curve radius(m/km), and sum of each intersection angle($^{\circ}/km$). 4. Slope(%) were closely correlated with plane alignment, and so were the relationships between frequency of valleys and streams(No./km) and elongation coefficients(${\eta}$) of forest road.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.150-151
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• 2000

비선형광학은 1962년 Franken과 그 동료진에 의하여 루비 레이저빛을 수정결정에 입사시킨 결과로 루비 레이저파장의 반에 해당하는 자외선빛의 발생을 관찰한 이후 지난 40년간 급속히 발전해온 광학의 한 연구분야로, 물질내에 전기장에 대하여 2차이상에 비례하는 분극이 유도됨으로 인하여 생기는 모든 효과를 통칭 비선형광학효과라고 한다. 그중 제2차 비선형현상은 광전효과를 이용한 빛변조, 제2차고조파 발생 및 합/차 주파수파발생을 통한 다양한 파장의 결맞은 광원으로서 응용되고 있을 뿐 아니라, 제3차 비선형현상으로 Optical bleaching, 자체집광/퍼짐, 광학적 고립파 및 Optical Switching 등 빛을 이용한 빛제어(Light control by light)를 할 수 있는 응용성이 있어 오늘날 까지도 활발한 연구가 진행되고 있다. (중략)

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.75-82
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• 2002

This paper propose a new mathematical modelling method about optimum operational schedule for cogeneration systems. Proposed algorithm solving the energy product cost function in this paper is very similar to the real model that is, proposed algorithm solve nonlinear type of real model using mixed integer programming based on the piecewise linear function while the conventional algorithms used before could not solve that kind of problems. The effectiveness of the proposed method is ascertained by the simulation results with varius case studies which are similar to real operation circumstances.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.6
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• pp.56-66
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• 1998

This paper investigates a neuro-controller combined in parallel with a conventional linear controller of PID type in order to control nonminimum phase systems more efficiently. The objective is to minimize overall position errors as well as to maintain small undershooting. A costfunction is proposed with two conflict objectives. The neuro-controller is trained off-line with evolutionary programming(EP) in such a way that it becomes optimal by minimizing the given cost function through global evaluation based on desired control performance during the whole training time interval. However, it is not easy to find an optimal solution which satisfies individual objective simultaneously. With the concept of Pareto optimality and EP, we train the proposed controller more effectively and obtain a valuable set of optimal solutions. Simulation results show the efficacy of the proposed controller in a viewpoint of improvement of performance of a step response like fast settling time and small undershoot or overshoot compared with that of a conventional linear controller.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.363-370
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• 1999

This study presented an modeling method for the connections in mixed structure with reinforced concrete columns and steel beam using finite element method. The contacting surfaces between concrete and steel are modeled using master-slave contact algorithm and the incompatible mode elements were used in the steel tube subjected to bending. The characteristics of mixed structure was that diaphragm was used for transferring force from beam to column. The three dimensional nonlinear analysis was performed and the analytical results compared with experimental results in order to prove modeling method.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1243-1251
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• 2010

For clinical trials, it is common to compare the placebo and new drug. The method of calculating a sample size for two independent populations are the t-test that is used for parametric methods, and the Wilcoxon rank-sum test that is used in the non-parametric methods. In this paper, we propose a method that is using Kim's (1994) statistic power based on the linear placement statistic, which was proposed by Orban and Wolfe (1982). We also compare the sample size for the proposed method with that for using Wang et al. (2003)'s sample size formula which is based on Wilcoxon rank-sum test, and with that of t-test for parametric methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1333-1342
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• 1992

This paper deals with a robot manipulator having actuator which is described by equation $D(q)\ddot{q}=u-P(q\;\dot{q},\;\ddot{q})$ where u(t) is a control input. We employ two steps of controller design procedures. First, a global linearization is performed to yield a decoupled controllable linear system. Then a controller is designed for this linear system. We provide a rigorous analysis of the effect of uncertainty of the dynamics, which we study using robustness results in time domain based on a Lyapunov equation and the total stability theorem. Using this approach we simulate the performance of controller of a robot manipulator.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.774-777
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• 2010

본 논문에서는 MR 감쇠기의 비선형 특성을 등가의 선형감쇠로 치환하기 위한 방법으로 Newmark와 Hall이 제안한 감쇠계수를 이용하였다. 응답스펙트럼의 감쇠율을 나타내는 감쇠기계수는 구조물의 최대변위를 이용하여 등가감쇠비를 추출할 수 있다는 장점을 가지고 있다. 하지만 이러한 응답스펙트럼은 구조물에 작용하는 지진하중의 특성에 따라 경향이 달라진다. 본 논문에서는 기존의 등가감쇠비 산정식을 수정하여 제안하고, 지진하중 특성에 따른 등가감쇠비의 변화를 살펴보았다. MR 감쇠기의 등가감쇠비는 가진하중과 최대마찰력의 비율에 따라 결정되며, 장주기 구조물의 경우 등가감쇠비가 감소한다. MR 감쇠기의 점성은 마찰감쇠와의 상호작용에 의해 단순한 산술합 이상의 감쇠비 증가 효과를 가진다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1207-1209
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• 2005

원통형 선형 동기 전동기의 디텐트력은 고정자 안쪽의 치와 영구자석 사이에서 작용하는 힘과 고정자 바깥쪽의 치와 영구자석 사이에서 작용하는 힘의 합이며, 일반적으로 고정자 바깥쪽의 치와 영구자석 사이에서 작용하는 단부효과에 의한 힘이 훨씬 크다. 이 단부효과에 의한 힘을 줄이기 위한 방법으로 고정자의 길이 조정 및 챔퍼링이 있으며, 이를 통하여 원통형 선형동기 전동기 고정자의 형상을 최적 설계한다.