• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.427-428
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• 2008

In order to probe such mineral resources, AUVs (Autonomous Underwater Vehicles) have been used instead of ROVs (Remotely-Operated Vehicles) that are not suitable to probe submarine resources distributed over a wide area. However, the power consumption of AUVs needs to be reduced as they are operated by batteries. In controlling the power of underwater vehicles, the efficiency of batteries and their capacity have been heightened. This study aimed at developing a power control system suitable to the prober for submarine mineral resources. As a result, power was reduced as compared to the non-control system and the prober could explore the seabed longer than usual.

• 항공우주시스템공학회지
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• 제18권2호
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• pp.71-78
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• 2024

초기 열설계 과정의 경우 복잡한 궤도 열 환경 조건에서 다양한 설계 변수에 따른 열적 영향성 판단을 해야 하므로, 열 설계/분석에 많은 시간이 소요된다. 따라서, 초기 설계 단계에서 시간을 효율적으로 단축시키기 위해서는 최적의 설계 변수 도출과 이에 따른 온도 예측이 신속히 이루어져야 한다. 상기 문제점에 기인하여 차수축소모델을 활용한 최적 설계 전문 소프트웨어인 Veritrek이 2018년에 출시되었다. 본 논문에서는 Veritrek 소프트웨어를 활용하여 그라파이트시트 기반 냉각기 열 제어 시스템에 대해 차수축소모델 구축과 민감도 분석, 최적 설계 분석을 수행하여 냉각기의 허용온도를 만족할 수 있는 그라파이트시트의 적층 수, 방열판 면적 및 두께에 대한 최적설계 수치를 도출하였다.

• 한국정밀공학회지
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• 제6권4호
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• pp.52-60
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• 1989

In order to control the transient torsional vibration of rotational shaft system, the torsional stiffness of it has been taken into account in modelling the plant. In this paper the observer and controller has been designed in two ways. One is to consider the torsional stiffness and the other is to idealize the rotational shaft as rigid body. The third order observer considering torsional stiffness shows stable response on computer simulation. When the observer is designed on assumption of the rotational shaft being rigid body, the reduced order observer shows stable response whereas the full order observer shows unstable response.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1985년도 하계학술회의논문집
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• pp.47-48
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• 1985

This paper is concerned with the problem of designing satisfactory low-order controller starting with a high-order, state space model. The success of a design approach is rooted in the Choice of a model reduction procedure. The powerful new reduction method of a modal approach was already evaluated /1/. Application of the technique to a simulated steam generator is demonstrated for the case of modal control with low-order controllers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.62.3-62
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• 2002

In this paper, we proposed a control technique that can be applied to various processes. The most of the process can bereduced to second order plus time delay (SOPTD) model. And we proposed improved model reduction algorithm using geneticalgorithm. This method considered four points to reduce the error between original model and reduced model in the Nyquistcurve. And, to compensate time delay, the Smith predictor plus PID controller is adopted. And a new PID tuning algorithm wasproposed, which got from numerical analysis and can be obtained the optimal performance. The PID parameters are obtainedfrom the coefficients and time delay of reduced model. The simulation results show the validity.

• International Journal of Control, Automation, and Systems
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• 제2권3호
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• pp.384-389
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• 2004

Recently a method of model reduction for discrete systems has been proposed in the literature based on a new impulse response Gramian. In this method, the system matrix$A_r$ of a reduced model is computed by approximating the reduced-order impulse response Gramian. The remaining matrices $b_r$ and $c_r$ are obtained so that various initial Markov parameters and time-moments of the original system are preserved in the reduced model. In this paper a different approach is presented based on the recursive relationship among the impulse response Gramians.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.647-650
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• 2004

The modeling of an active vibration isolation system is accomplished by using the equivalent spring constant, mass and rotational Inertia of each component. The detailed model of the actuation module is successful for describing its frequency-domain performance but also too complicated to implement it to actual system for control so that the order of the model is reduced up to the degree that preserves its characteristic in the low frequency range. The reduced model is suitable for identifying the unknown system parameters such as damping constants of components. The overall isolation system is described by using the reduced model of the actuation module. The accurate model ing and system parameter identification that is essential for the control of the active vibration isolation system is attained successfully.

• 소음진동
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• 제2권3호
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• pp.173-180
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• 1992

A boundary control method that controls interior state by actively controlling the boundary conditions in boundary value problems is proposed for the vibration control of flexible beam by using piezoelectric actuators. The governing equations are derived based on the Euler beam theory and the reduced order model is obtained by modal truncation. The spillover effects caused by the uncontrolled high frequency modes are analyzed and the method selecting a suitable sensor location is also proposed. The lag compensator in digital form is realized by using a microcomputer and its peripheral devices. The efficiency of the proposed control scheme is demonstrated experimentally and compared with the simulation results.

• 한국환경보건학회지
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• 제16권1호
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• pp.29-43
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• 1990

The purpose of this study is to investigate the vairous change in the toxicity of cadmium by the simultaneous administration of selenium and zinc, which have been reported to change -the toxicity of cadmium through the interaction with cadmium, to rat. For the experiment, 42 rats of Sprague-Dawley strain were used. The experimental groups were divided into 6 groups: a control group, a cadmium (100ppm) alone treatment group, a cadmium (100ppm) and zinc (100ppm) combined treatment group, and three cadmium (100ppm), zinc (100ppm) and selenium (1, 4, and 8ppm) combined treatment groups. The rats were allocated seven to each group and observed for seven weeks. The results of experiment are as follows: 1. The food consumptions of each group were reduced, compared with a control group, especially, in a cadmium and zinc combined treatment group and a cadmium $\cdot$ zinc and selenium(1ppm) combined treatment group to the significant level compared with a control group (p < 0.05). The water consumptions of each group were reduced to the very significant level compared with a control group (p < 0.01). The feed efficiencies of each group were lower than a control group, and among them the highest group was cadmium $\cdot$ zinc and selenium (8ppm) combined treatment group as 90% of a control group. 2. In all groups, the weight gains were highest in the second week and the total weight gains were reduced to the very significant level compared with a control group (p < 0.01). 3. In all groups, the relative weights of liver were reduced, compared with a control group, especially, a cadmium alone treatment group was reduced to the significant level (p < 0.05). The relative weight of kidney was high to the significant level in a cadmium alone treatment group (p < 0.05) compared with a control group. In all groups, the relative weights of testis were reduced, compared with a control group, but the levels were not significant. 4. The accumulation of cadmium was highest in the kidney and the order of height was in liver, testis and blood, respectively. In all groups, the amount of cadmium accumulation was high to the very significant level compared with a control group (p < 0.01). In liver, the amount of acdmium accumulation in. a cadmium alone treatment group was high to the significant level compared with a cadmium $\cdot$ zinc and selenium (8ppm) combined treatment group (p < 0.05), and in kidney, the amount of cadmium accumulation in a cadmium alone tretment group was high to the very significant level compared with the cadmium $\cdot$ zinc and selenium (4, 8ppm) combined treatment groups (p < 0.01). However, in testis, among the treatment groups the level was not significant and in blood, a cadmium alone treatment group was low to the significant level compared with the cadmium $\cdot$ zinc and selenium (4, 8ppm) combined treatment groups (p < 0.05). 5. According to the histopathological finding on the testis, some of the seminiferous tubules of a group treated with cadmium alone showed severe necrosis and atrophy. But the testis of cadmium $\cdot$ zinc and selenium (8ppm) combined treatment group was similar to that of a control group. From the results of this study, it can be concluded that the repeated simultaneous oral administration of large doses of selenium with the cadmium produces the partial amelioration of cadmium toxicity, whereas zinc does not.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.921-926
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• 2007

A dynamic system under random disturbance is considered in the study. In order to control the system efficiently, proper reduction of system dimension is indispensible in design stage. The reduction method using component cost analysis in conjunction with stochastic analysis is proposed for the control of a system. System response is obtained in terms of dynamic moment equation via Fokker-Plank-Kolmogorov(F-P-K) equation. The dynamic moment response of the system under random disturbance are reduced by using of deterministic version of component cost analysis. The reduced system via proposed "stochastic component cost analysis" is successfully implemented for dynamic response and shows remarkable control performance effectively utilizing "stochastic controller" in physical time domain.