• Nuclear Engineering and Technology
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• 제35권4호
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• pp.261-273
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• 2003

The characteristics of the recirculation operation of LMR which are different from the conventional plants such as PWR and fossil fuel plants were investigated using a computer code TSGS developed in this study. For simulating the transient behavior of the steam generation system, a water level control algorithm utilizing digital control hardware features was introduced. By investigation, the function of the recirculation operation was defined, the major features of the operation were found. Also good performance of the level control algorithm was confirmed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.945-946
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• 2006

This paper presents a detailed small-signal and transient analysis of a Three-Level zero-voltege-switched PWM converter designed for high voltage, high power applications using an average model.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.361-362
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• 2015

This paper proposes a Direct Power Control (DPC) scheme of improved command tracking capability for Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) Wind Turbines. Benchmarking is performed based on a neutral point clamped three-level back-to-back type voltage source converter. It is introduced to design the DPC modeling and propose DPC scheme of a three-level NPC (3L-NPC) converter. During the fault condition in wind farms, the proposed control scheme directly controls the generated output power to the command value from the hierarchical wind farm controller. The proposed control scheme is compared with conventional control scheme as respect to loss and thermal analysis. The DPC scheme of improved command tracking capability is confirmed through PLECS simulations. Simulation result shows that proposed control scheme achieves a much shorter transient time in a step response of generated output power. The proposed control scheme makes it possible to provide a good dynamic performance for PMSG MV wind turbine to generate a high quality output power under grid fault condition.

• Journal of the Optical Society of Korea
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• 제11권4호
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• pp.153-157
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• 2007

We have proposed an application of disturbance observer with PID controller to minimize gain-transient time of wavelength-division-multiplexing(WDM) multi channels in optical amplifier in channel add/drop networks. We have dramatically reduced the gain-transient time to less than $3{\mu}sec$ by applying a disturbance observer with a proportional/integral/ differential(PID) controller to the control of amplifier gain. The theoretical analysis on the 3-level erbium-doped fiber laser and the disturbance observer technique is demonstrated by performing the simulation with co-simulation of the $MATLAB^{TM}$ and a numerical modeling software package such as the $Optsim^{TM}$.

• Journal of Advanced Marine Engineering and Technology
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• 제17권5호
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• pp.54-62
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• 1993

Generally, the main difficulty in the composition of tank-level control system may be in the point that plant parameters are severely varied according to the change of operating point. In order to cope with this difficulty, in this paper, an adaptive control is employed using model-following technique based on the optimal control law. Through the simulations and experiments the following results were observed. 1) The steady-state error was not found under the parameter variations caused by the change of operating point. 2) In spite of the change of operating point, the corresponding gains which were stored in the computer were found to be automatically updated so that the controller could have the adaptive ability. And also, the control specifications in view of transient response were found to be satisfied.

• Nuclear Engineering and Technology
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• 제25권3호
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• pp.371-380
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• 1993

운전원의 언어적인 제어 논리를 이용한 모델과 무관한 제어기가 증기 발생기의 수위 제어를 위해 개발되었다. 오직 9개의 룰을 수위 오차와, 응축 수위 변화를 표현하는 유량 오차로부터 얻어졌다. 벨형의 소속함수는 민감도 분석을 통하여 조절되었고, 결과 과도 상태와 정상상태 공히 양호한 제어성능을 보였다. 저출력에서 전 출력까지의 다단계 출력 증가에 대하여, 전 운전 영역에서 좋은 제어를 보였다.

• 전기학회논문지
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• 제59권5호
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• pp.904-911
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• 2010

This paper presents the design of acoustic resonance free and over current limit during transient state consideration electronic ballast for 1.5kW Metal-Halide Lamp(MHL) that employs frequency modulation (FM) technique. The proposed ballast consists of a Full-Bridge(FB) rectifier, a passive power factor correction (PFC) circuit, a full-bridge inverter, an ignitor using LC resonance and a control circuit for frequency modulation. The frequency modulation technique is the most effective solution to eliminate acoustic resonance among other technique. It spreads power spectrum of lamp to reduce the supplied power spectrum under the energy level of eigen-value frequency. Moreover, the proposed ballast is simple and cost effective above conventional ballast. A new PFC circuit is proposed which combines with LCD type and PCSR filter. A new PFC circuit has higher PF and lower THD than conventional LCD type and secure high reliability. Finally, to protected switching components in transient state, the surge current into ballast is limited by increase the switching frequency. Performance of the proposed ballast was validated through computer simulation using Pspice, experimentation and by applying it to an electronic ballast for a prototype 1.5kW MHL.

• 대한전자공학회논문지
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• 제12권4호
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• pp.15-20
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• 1975

원자로의 출력을 초기상태에서 요구표적 상태로 증가시켜 주는 과도기간중 출력의 Overshoot가 생기는데 이 Overshoot에 구속조건을 두는 것은 원자로를 제각함에 있어 안전사 매우 중요하다. 따라서 출력이 요구 최대허용 구동영역을 넘지 않도록 반응도를 조절하면서 초기값(no, co)에서 최종같인 요구값(2no,2co) 또는 (1. 5no,1.5co)로 출력을 증가시키는데 최대원리(Maximum principle)를 적용하였다. 그리고 이때의 스위청점, 스위청시간 및 최적제각 반응도를 구하였다. The power overshoot is rises in the output during the transient period when the output of nuclear reactor is increased from the initial state to the desired target state and certain amount of constraint on power level is of primary importance for safety control of nuclear reactor. Therefore, the maximum principle is applied to this process control in transfering its power from the initial state(no, co) to the final target state(2no, 2co or 1.5no, 1.5co), adjusting the reactivity so that its overshoot is limited within the allowable constraint required. In this case, the switching points, switching times, optimal lima and optimal control reactivity are calculated.

• Nuclear Engineering and Technology
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• 제26권3호
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• pp.420-424
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• 1994

가압경수로형 원자력발전소의 저출력 및 과도상태에서의 개선된 증기발생기 수위 제어 방식을 제시하였다. 수축 및 팽창 현상에 의한 수위의 요동을 줄이기 위해 기존의 비례·적분 제어기에 증기발생기 압력 및 급수온도를 고려한 앞먹임 보상부를 첨가하였다. 원전 훈련용 시뮬레이터를 이용하여 시뮬레이션을 수행한 결과 기존방식에 비해 적은 수위오차, 훨씬 빠른 진정시간을 얻을 수 있었다. 제시된 알고리즘은 구현이 용이하고 실제 적용도 가능하리라 판단된다.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.146-154
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• 2015

This paper proposes a control method for maintaining the energy level for a supercapacitor energy storage system coupled with a wind generator to stabilize wind power output. Although wind power is green and clean energy source, disadvantage of the renewable energy output power is fluctuation. In order to mitigate the fluctuating output power, supercapacitor energy storage system (SCESS) and wind power simulator is developed. A remaining energy supercapacitor (RESC) control is introduced and analyzed to smooth for short-term fluctuating power and maintain the supercapacitor voltage within the designed operating range in the steady as well as transient state. When the average and fluctuating component of power increases instantaneously, the RESC compensates fluctuating power and the variation of fluctuating power is reduced 100% to 30% at 5kW power. Furthermore, supercapacitor voltage is maintained within the operating voltage range and near 50% of total energy. Feasibility of SCESS with RESC control is verified through simulation and experiment.