• 대한기계학회논문집A
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• 제37권4호
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• pp.475-481
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• 2013

직접구동형 서보밸브의 제어시스템은 비선형적이며 밸브스풀에 미치는 유체력의 영향은 매우 크고 부하압력의 크기에 좌우된다. 제어시스템의 설계요구조건을 만족시키기 위해, 제약직접탐색방법인 유전자 알고리즘과 콤플렉스법을 적절히 활용하여 진상-지상제어기 및 미분피드백제어기의 최적 상수값을 탐색하였다. 최적 제어기 상수값을 대입하여 제어시스템을 시뮬레이션한 결과 설계요구조건을 만족하였다.

• 전기학회논문지
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• 제59권1호
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• pp.152-159
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• 2010

This paper describes the actual application of a feedback control loop as a means for minimizing turbine impulse chamber pressure variation during the turbine steam valve tests at a 1,000 MW nuclear power plant. The chamber pressure control loop was implemented in the new digital control system which was installed as a replacement for the old analog type control system. There has been about 40MW of the generator output change during the steam valve tests, especially the high pressure governing valve tests, because the old control system had not the impulse chamber pressure control so the operators had to compensate steam flow drop manually. The process of each valve test consists of a closing process and an reopening process and the operators can make sure that the valves are in their sound conditions by checking the valves movement. The control algorithm described in this paper contributed to keep the change in megawatt only to 6MW during the steam valve tests. Thereby, the disturbance to reactor control was reduced, and the overall plant control system's stability was greatly improved as well.

• Nuclear Engineering and Technology
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• 제26권1호
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• pp.32-40
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• 1994

중기발생기의 수위조절과 관련하여 최적제어이론을 이용한 디지탈 제어시스템을 설계하였다. 우선 급수변을 일차 지연함수로 취급하여 전체 시스템에 포함시킴으로써 보다 실제에 가까운 시스템이 되게 하였다. LQ 방법을 이용하여 급수변의 작동 및 요구신호량과 급수출력과의 차이를 최소화시킬 수 있는 최적 이득상수를 결정하였으며, 아울러 저출력에서의 급수유량 측정이 불확실함을 고려하여 급수신호에 대한 칼만 관측기를 설계하였다. 그리고 전출력 구간에서 일정한 안정여유도를 유지시킬 수 있는 가변상수 디지탈 제어기를 설계하였다. 이러한 제어시스템은 보다 현실적인 상황을 반영하고 있으며 저출력에서 급수와 반대현상을 보이는 중기발생기의 동특성에도 불구하고 만족할만한 제어특성을 보이고 있다.

• Journal of Power Electronics
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• 제16권4호
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• pp.1526-1540
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• 2016

This work mainly discusses an accurate and fast islanding detection based on fractional wavelet packet transform (FRWPT)for multibus microgrid systems. The proposed protection scheme uses combined desirable features retrieved from discrete fractional Fourier transform (FRFT) and wavelet packet transform (WPT) techniques, which provides precise time-frequency information on minute perturbation signals introduced in the system. Moreover, this study focuses on the design of decoupling control with a distributed controller based on state feedback for the efficient operation of microgrid systems that are transitioning from the grid-connected mode to the islanded mode. An IEEE 9-bus test system with inverter based distributed generation (DG) units is considered for islanding assessment and smooth operation. Finally, tracking errors are greatly reduced with stability improvement based on the proposed controller. FRWPT based islanding detection is demonstrated via a time domain simulation of the system. Simulated results show an improvement in system stability with the application of the proposed controller and accurate islanding detection based on the FRWPT technique in comparison with the results obtained by applying the wavelet transform (WT) and WPT.

• Journal of Advanced Marine Engineering and Technology
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• 제29권8호
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• pp.929-937
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• 2005

A lattice BGK model based on a finite difference scheme with an internal degree of freedom is employed and it is shown that a diatomic 9as such as air is successfully simulated In a weak compressive wane problem and Coutte flow, the validity and characteristics of the applied model are examined. With the model. furthermore. we present a 2-dimensional edge tones to predict the frequency characteristics of discrete oscillations of a jet-edge feedback cycle by the FDLB model (I.D.F FDLBM) in which any specific heat ratio $\gamma$ can be chosen freely. The jet is chosen long enough in order to guaranteed the Parabolic velocity profile of a jet at the outlet. and the edges have of an angle of $\alpha$=$23^{0}$ and $20^{0}$. A sinuous instability wane with real frequency resulting from Periodic oscillation of the jet around the edge is propagated on the upper and lower of wedge.

• 소성∙가공
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• 제13권3호
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• pp.253-261
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• 2004

The machining technology for the brittle materials such as ceramics are applied to the fields of MEMS(micro electromechanical system) by the progress of new machining technologies such as Etching, Diamond machining, Micro drilling, EDM(Electro discharge machining), ECDM(Electro discharge machining), USM(Ultrasonic machining), LBM(Laser beam machining), EBM(Electron beam machining). Especially, the USM technology can be applied to the dieletric brittle materials such as silicon, borosilicate glass, silicon nitride, quartz and ceramics with high aspect ratio. The micro machining system with machining force controlled position servo is developed in this paper and the optimized ultrasonic machining algorithm is constructed by the force controlled position servo control. The load cell is adapted in the force measuring and the servo control algorithm, suit for the ultrasonic machining characteristics, is estabilished with using the PID auto-tunning functions at the PMAC system which is generally adapted in the field of robot industries. The precision force signal amplifier is constructed with high precision operational amplifier AD524. The vacuum adsorption chuck which is made of titanum and internal flow line is engraved, is used in the workpiece fixing. The mahining results by USM shows that there are some deviation between the force command and the actual machining force that the servo control algorithm should be applied in the machining procedures. Therefore, the constant force controlled position servo system is developed for the micro USM system and by the examination machining process in USM, the stable USM system is realized by tracking the average value of machining force.

• 한국정보통신학회논문지
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• 제13권5호
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• pp.906-912
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• 2009

오프라인에서는 학습자와 교수자간의 직접적인 학습 내용 전달과 의사소통으로 보다 효율적인 학습이 이루어진다. 이에 가상 학습에서는 특정 학습 영역에 대한 검색 기능과 평가 후 관련 학습 영역으로의 자동 피드백 연결등의 기능으로 이러한 부분을 해결하고 있다. 그러나 검색결과에서 가장 적합한 학습 영역을 선택하고, 현재의 학습을 위해 선행되어져야 할 이전 학습 영역을 선택하는 것들이 학습자의 몫이기 때문에 학습 내용에 익숙하지 않은 학습자에겐 오프라인 학습에 비해 많은 어려움이 따른다. 본 논문에서는 학습자가 전체 학습 내용의 흐름과 단원간의 연관성 및 학습 방향을 잡는데 도움을 줄 수 있는 보다 다양한 시각에서의 색인 메커니즘을 제안한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.888-889
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• 2015

본 논문에서는 입베디드세스템에 기초를 둔 시스템온칩을 구성하는 방법을 제안하였다. 제안한 방법은 이전의 방법에 비해 좀 더 콤팩트하고 효과적이다. 이 방법은 높은 수행시뮬레이션을 요구하고 하드웨어/소프트웨어 통합설계 툴을 사용하여 구현을 위한 실행 가능한 규격화된 적절함을 요구한다. 시스템 인터페이스 처럼 이미 존재하고 있는 부품의 재사용은 지원되지만, 작업 이후는 단지 하드웨어/소프트웨어 통합설계 툴의 프로그램에 의해 수행되어진다. 실제 설계 흐름은 모든 프로세스를 통하여 요구되는 구현으로부터 모든 설계 단계 사이의 궤환을 허용하게끔 설명되어진다. 향후 좀 더 진보된 임베디드시스템에 기초를 둔 시스템온칩을 구성하는 방법이 요구된다.

• 수산해양교육연구
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• 제24권2호
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• pp.210-223
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• 2012

The importance on the flow to the lifelong education system has been growing, as the eternal education is in a pivotal position according to the education system all over the world is changing rapidly. In particular, although consolidating instructor competencies for lifelong education have become the subject of conversation, there has not been any clear concept of lifelong education instructors nor of the competencies for those. So this research defined lifelong education instructors who work at various lifelong education facilities, especially those who focus on lectures, and the instructor competencies, and make analysis and deductions what types of competencies are necessary for effective and efficient teaching. For this, the researcher derived the concept of instructors and the instructor competencies for lifelong education through document analysis, and based on that, discovered the instructor competencies for lifelong education by experts review and survey. The result revealed that there were four types of instructor competencies for lifelong education, which were planning, managing, administrating, and supporting and encouraging students. There were searching needs of students, analyzing, and 13 other criteria for planning; managing human resources, materials management, and 7 other for managing; expertise in learning contents and 13 other for administrating; and giving feedback and 3 other for supporting and encouraging students.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.961-966
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• 2009

This paper presents precise temperature control of oil outlet in an oil cooler with hot-gas bypass control as an industrial refrigerator. The control system was designed for obtaining precise temperature control performance even though abrupt disturbances based on flow rate control of hot-gas bypass. PID controller was adopted in feedback control system. We showed that the gain of PID could be easily determined by using gain-tuning methods without any numerical model. Through some experiments, excellent control performances such as overshoot within 1.7%, steady state temperature error within ${\pm}0.1^{\circ}C$ were established by a simple PI controller. We expect that the system can control the target temperature within error of $0.33^{\circ}C$ under abrupt disturbances.