• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5306-5313
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• 2011

Most previous studies for finding optimal design parameters of a tuned mass damper(TMD) have been focused on the harmonic excited single-degree-of freedom system. In this study, optimal values of damping ratio and tuning frequency ratio of a TMD applied to control a seismically excited structure are investigated through numerical analyses. Considering that the structural responses due to earthquake loads are strongly dependent on the soil condition, the site effects on the optimal parameters of the TMD are studied and compared to those presented by previous studies. Numerical analyses results indicate that better control performance can be obtained by using the parameters proposed by this study in the seismic application of the TMD.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.32-44
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• 2015

In general, a series of ship steering motion is represented by the combination of translational motion and rotational motion of the ship. Especially, special-functioned ships such as large-scale cruises, ships for installing underwater optical cable, and diver ships must be able to reveal only a translational motion without the change of orientation. In this paper, a method to comprise an integrated control system based on the joystick as a command instrument for translational motion control is suggested. In order to realize the translational motion control system, several algorithms are suggested including the velocity command generation, the selection of motional variables, and the generation and tracking of reference inputs for the selected motional variables. A simulation bench is composed to execute simulations for several translational motion commands. At last, the effectiveness of the proposed method is verified by analyzing the simulation results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.4
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• pp.165-171
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• 2018

In this study, the shape of the flow control structure within a DVR was designed for heat dissipation of the CPU. The proposed design consists of three thin metal plates, which directly controls the air flow inside the DVR box and forces the air to pass through the CPU, thereby efficiently dissipating heat from the CPU. The shape of the structure was determined using parametric studies. To verify the design result, we carried out a three-dimensional time dependent numerical analysis using a commercial fluid dynamics analysis package FlowVision. As a result of experiments with a real DVR equipment, it is confirmed that the temperature of the CPU is significantly reduced compared to the initial model.

• Journal of the Korean Institute of Intelligent Systems
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• v.3 no.2
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• pp.18-35
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• 1993

The water level control system of the steam generator in a pressurized water reactor and its control problems are analysed. In this work the stable control strategy during the low power operation and transient states is studied. To solve the problem, a fuzzy logic control method is applied as a basic algorithm of the controller. The control algorithm is based on the operator's knowledges and the experiences of manual operation for water level control at the compact nuclear simulator set up in Korea Atomic Energy Research Institute. From a viewpoint of the system realization, the control variables and rules are established considering simpler tuning and the input-output relation. The control strategy includes the dynamic tuning method and employs a substitutional information using the bypass valve opening instead of incorrectly measured signal at the low flow rate as the fuzzy variable of the flow rate during the pressure control mode of the steam generator. It also involves the switching algorithm between the control valves to suppress the perturbation of water level. The simulation results show that both of the fine control action at the small level error and the quick response at the large level error can be obtained and that the performance of the controller is improved.

• Journal of Broadcast Engineering
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• v.2 no.2
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• pp.194-205
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• 1997

In video compression standards such as MPEG and H.263. rate control is one of the key components for good coding performance. This paper presents a simple adaptive rate control scheme using a piecewise linear approximation model. While conventional buffer control approach is performed by adjusting the quantization parameter linearly according to the buffer fullness. the proposed approach uses a piecewise linear approximation model derived from logarithmic relation between the quantization parameter and bitrate in data compression. In addition. a forward analyzer performed in the spatial domain is used to improve image quality. Simulation results demonstrate that the proposed method provides better performance than the conventional one and reduces the fluctuation of the PSNR per frame while maintaining the quality of the reconstructed frames at a relatively stable level.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.56-65
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• 1998

In this paper, a neural network(NN) control system is proposed and practically implemented, which is adequate to the induction motor speed control system with frequent load variation. The back propagation neural network technique is used to provide a real adaptive estimation of the motor parameter. The error between the desired state variable and the actual one is back-propagated to adjust the motor parameter, so that the actual state variable will coincide with the desired one. Designed control system is based on PC-DSP structure for the purposed of easiness of applying NN algorithm. Through computer simulation and experimental results, it is verified that proposed control system is robust to the load variation and practical implementation is possible.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1333-1337
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• 1987

본 연구는 머리운동 제어 시스템에 대한 생체 물리학적인 모델링과 시뮬레이션을 통하여 모델의 동특성을 조사하였으며, 생체운동(머리-안구)의 상호 관계를 비교하였다. 결과를 요약하면 다음과 같다. 1) 시스템을 구성하고 있는 매개변수의 변화가 출력에 미치는 영향을 조사하기 위해 감도해석법을 써서 감도계수를 구한 결과, 입력 제어신호의 펄스높이(PH), 동근의 펄스폭(PW1), 길항근의 펄스폭(PW2)이, 시스템의 출력특성을 결정하는 가장 중요한 매개변수 임을 알 수 있었다. 2) 비 선형 제어모델의 선형화를 통하여 선형모델의 응답특성과 크나큰 차이가 없음을 알았다. 3) Main-Sequence도를 작성하여 실험 데이터와 비교한 결과, 거의 일치함으로서 모델의 타당성을 입증하였다. 4) 머리운동이 시간최적으로 응답하기 위해서는 bang-bang 제어법칙이 적용되어야 함을 알았다. 5) 머리운동이 목표점에 도달하는 순간에는 길항근의 역제통 펄스가 가해 짐으로서, 길항근이 궤적의 마지막 부분을 지배함을 알았다. 6) 머리-안구운동의 main-sequence도를 비교 함으로서 상호관계를 규명하였다. 앞으로는 이 모델링 법을 개선확장하면, 비행시 파일럿의 생체 시뮬레이션, 헬멧 조준 사격 시스템등의 항공공학, 생체의용공학 연구 및 제어입력을 생체신호로 하는 로봇틱스 연구에 본 연구 방법은 유용하리라 생각된다.

• KSBB Journal
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• v.18 no.5
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• pp.418-423
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• 2003

A laboratory jar fermenter was modified to measure the duration for cooling water supply and the temperatures of the coolant at the inlet and outlet of water jacket. Successful operation of temperature control and on-line measurement was achieved by adjusting optimum parameters of the Proportion-Integral-Derivative temperature controller. The variables measured on-line were used to estimate cooling rates from empirical equations comprised of the time period of cooling water supply and the temperatures of coolant. The measured cooling rate showed a good correlation to the specific growth rate during batch cultivation of E. coli. Cooling rate was measured and applied to programmed cell growth in a fed-batch cultivations. Three fed-batch cultivations were demonstrated by feeding substrate to follow the programmed cooling rates increasing exponentially.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.113-122
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• 2002

Control system modeling and optimal bending filter design for KSR-III (Korea Sounding Rocket III) are performed. Rigid rocket dynamics, aerodynamics, sloshing, structural bending, actuator dynamics, sensor dynamics and on-board computer characteristics are considered for control system modeling. Compensation for time-varying control system parameters is conducted by gain-scheduling. A filter to stabilize bending mode is designed using parameter optimization technique. Resultant attitude control system can satisfy required frequency domain stability margin.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.35-44
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• 1989

In this paper, a precisely speed-controlled DC servo motor system utilizing direct adaptive control (DAC) algorithm which require that neither satisfaction of the perfect model following conditions (PMFC) nor explicit parameter identification is proposed. Computer simulation as well as experiments using MC-68000 are implemened with the above input trajectory fairly well in spite of load disturbances and parameter variations. Presented algorithm is simple and effective both in software and hardware applications.