• 동력기계공학회지
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• 제15권1호
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• pp.78-85
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• 2011

In order to design the control system of the magnetic bearing for the high speed 3 phase induction motor, the mathematical modeling was conducted and LQ regulator system was designed. When the plant is controllable and detectable, the nominal stability of LQ regulator could be guaranteed. However, LQ regulator doesn't ensure the robustness of stability and performance for the real system because LQ control is the mathematical optimal theory. In this paper to ensure the robustness of stability and performance for the real system, the control systems are designed by the simulation to the variation system parameters and this method was confirmed as an effective means.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.278-279
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• 2011

세계적으로 풍력 에너지에 대한 수요가 증가하고 있으며 이러한 풍력발전의 집중화 및 대규모화에 따라 풍력발전기가 고려된 계통의 해석이 필수적이며 이에 따라 풍력발전기가 고려된 계통의 해석을 위해 풍력발전기의 특성 및 출력을 파악 할 수 있는 정확한 모델링이 요구된다. 따라서 풍력발전기가 포함된 풍력발전단지의 모델링 및 조류계산 레벨에서의 무효전력보상 모델링의 방법을 정립해보며 이를 바탕으로 풍력 발전기가 포함된 모의 계통을 설계하였다.

• 유공압시스템학회논문집
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• 제8권2호
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• pp.23-28
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• 2011

This paper investigates the motion control of a hydraulic motor-load system using the Simple Adaptive Control (SAC) method. The plant transfer function has been modelled mathematically. The open-loop responses have been obtained experimentally in order to identify the design parameters of transfer function. The hydraulic motor-load system has been modelled using the 3D CAD and imbedded in the hydraulic circuit simulation program to verify the overall performance. The experimental results confirm that the SAC method gives a good tracking performance compared to the PID control.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.67-73
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• 2006

Uldolmok waterway is famous for its strong tidal current with maximum current of about 12knots, which is located between the Chindo island off the southwestern tip of Korean peninsula and mainland. A serious of field observations, along with numerical modeling, have been carried out over the last several years, in order to understand the tidal dynamics and to examine the related variables according to the tidal current power plant (TCPP) operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.392-394
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• 2001

Coal power plants are large, non-linear systems with numerous interactions between its component parts. In the analysis of such complex systems, dynamic simulation is recognized as a powerful method of keeping track of the myriad of interactions. This paper shows and discusses the developed analysis model, such as the forced draft fan the primary air fan, the furnace and burner system, air preheater and induced draft fan, etc. in accordance with BMCR condition of boiler using the Modular Modeling System(MMS) software.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.149-154
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• 1999

This paper describes a passive safety injection system with free piston Stirling pump working withabundant decay heat in the nuclear reactor during the hypothetical accident. The water column in the tube assembly connected from the hot chamber to the cold chamber in the pump oscillates periodically due to thermal volume changes of non-condensable gas in each chamber. The oscillating pressure in the water column is converted into the pumping power with a suction-and-bleed type valve assembly. In this paper a dynamic model describing the frequency of oscillation and pumping pressure is developed. It was found that the pumping pressure is a function of the temperature difference between the chambers. Also, the frequency oscillation depends on the length of the tube with water column.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.824-829
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• 2005

This paper focuses on construction cost volatility for the purpose of private sector investment by use of a financial model with key indices of IRR and DSCR (Debt Service Coverage Ratio). A case project, 1,000 MW pumped storage hydropower plant, has shown that its financial impacts by cost volatility of underground works are less measured than interest rates impacts by interest rate of loans. Probabilistic analysis of costs under geotechnical conditions has been made by Indicator Kriging method. And, in the modeling of interest rates, geometric Brownian motion has been applied. Both of these impacts are measured on the same financial model.

• Nuclear Engineering and Technology
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• 제41권6호
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• pp.785-796
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• 2009

A KALIMER-600 concept which is a type of sodium-cooled fast reactor, has been developed at KAERI. It uses sodium as a primary coolant and is a pool-type reactor to enhance safety. Also, a supercritical carbon dioxide ($CO_2$) Brayton cycle is considered as an alternative to an energy conversion system to eliminate the sodium water reaction and to improve efficiency. In this study, a simplified model for analyzing the thermodynamic performance of the KALIMER-600 coupled with a supercritical $CO_2$ Brayton cycle was developed. To develop the analysis model, a commercial modular modeling system (MMS) was adopted as a base engine, which was developed by nHance Technology in USA. It has a convenient graphical user interface and many component modules to model the plant. A new user library for thermodynamic properties of sodium and supercritical $CO_2$ was developed and attached to the MMS. In addition, some component modules in the MMS were modified to be appropriate for analysis of the KALIMER-600 coupled with the supercritical $CO_2$ cycle. Then, a simplified performance analysis code was developed by modeling the KALIMER-600 plant with the modified MMS. After evaluating the developed code with each component data and a steady state of the plant, a simple power reduction and recovery event was evaluated. The results showed an achievable capability for a performance analysis code. The developed code will be used to develop the operational strategy and some control logics for the operation of the KALIMER-600 with a supercritical $CO_2$ Brayton cycle after further studies of analyzing various operational events.

• 한국산학기술학회논문지
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• 제21권4호
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• pp.9-19
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• 2020

본 연구에서는 정격 출력 375 MW급의 석탄화력발전소의 보일러 및 보일러를 지지하는 철골의 유한요소해석을 위한 보일러-철골 통합모델을 개발하였다. 본 연구는 SAP2000 프로그램을 사용하여 지진하중에 대하여 통합모델을 해석함으로써 차후에 보일러와 철골의 안전성을 평가할 것을 염두에 두고 수행한 선행 연구이다. 보일러 내부의 수많은 관으로 구성되는 복잡한 과열기, 재열기, 절탄기, 멤브레인벽에 대하여 단순화 기법을 사용하여 강성과 관성의 관점에서 등가인 보요소, 쉘요소, 솔리드요소로 모델링하는 방법을 제시하였다. 그리고 보일러와 철골 간의 연결을 위한 모델링 방법도 제시하였다. 보일러를 철골의 거더에 매다는 역할을 하는 많은 행거는 개수를 줄여서 등가 행거로 변환하여 모델링하였다. 보일러 외벽의 벅스테이에 부착된 보일러 스토퍼는 스토퍼와 철골 기둥 사이의 연결 관계를 고려하여 변위를 연계시켜 모델링하였다. 개발된 보일러-철골 통합모델에 대하여 자중조건에 대한 정적해석을 수행하여 변형형태를 평가하였다. 자중조건에 대한 해석결과, 철골 부재들과 보일러의 주요 구성품들의 거동이 타당한 것으로 나타났다. 결론적으로 본 연구에서 개발된 통합모델은 보일러 및 보일러를 지지하는 철골의 지진에 대한 안전성 평가에 충분히 활용이 가능한 것으로 판단된다.

• 한국압력기기공학회 논문집
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• 제12권2호
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• pp.40-49
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• 2016

Flow accelerated corrosion (FAC) of the carbon steel piping has been a significant problem in nuclear power plants. FAC occurs under certain hydrodynamic, environmental, and material conditions, and extensive research into the factors of FAC has been conducted. The basic process of FAC is now relatively well understood; however, a full mechanistic model has not yet been established. Recently, the Korea Atomic Energy Research Institute (KAERI) has built a large experiment loop system for FAC. To produce significant experimental results using this system, the factors affecting on FAC should be analyzed quantitatively, and a model needs to be developed. In this work, a statistical modeling methodology to develop an empirical model is described in detail, and a preliminary model is suggested. Firstly, FAC data were collected from the research literature in Japan and the results of domestic experiments. The flow rate, water temperature, pH at room temperature, and the Cr content are selected as major factors, and nonlinear regression is used to find the best fit of the available data. An iterative procedure between suggesting and evaluating a model is used until an optimum model is obtained. The developed model gives the FAC rate comparable to the measured FAC rate. The developed model is going to be refined using additional laboratory data in the future.