• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.790-802
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• 2017

This paper proposes the modeling and control strategy to track the MPPs of hybrid PV and Wind power systems, using a new dual input boost converter. The dual input power conditioning system with an independent MPPT control scheme is introduced with minimum number of circuit elements in order to reduce the switching loss, size and cost of the system. Since the operating conditions for the PV and Wind power systems are very distinct from each other, an efficient and superior control system is required to track the MPPs of both renewable sources with the use of a simply-structured single-ended single-inductor converter. The design of Power-Conditioning System (PCS) and detail control strategy are presented in this paper. To provide independent tracking of MPPs, a variable duty-cycle control strategy is employed for the wind system and a variable frequency strategy is employed for the PV system. Finally, the proposed dual-input converter for hybrid power conditioning system is implemented and the hardware test results are presented. From the hardware experiment, it is concluded that the proposed system successfully tracks the MPPs of both of the renewable power systems independently.

• 대한전기학회논문지:전력기술부문A
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• 제48권4호
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• pp.402-409
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• 1999

Variable structure control law is well known to be a robust control algorithm and evolution strategy is used as an effective search algorithm in optimization problems. In this paper, we propose a variable structure controller with time-varying switching surface. We calculate the maximum value of seitching surface gradient that is of the 3rd order polynomial form. Evolution strategy is used to optimize the parameters of the switching surface gradient. Finally, the proposed method is applied to position tracking control for BLDC motor. Experimental results show that the proposed method is more useful than the conventional variable structure controller.

• Journal of Power Electronics
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• 제19권1호
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• pp.201-210
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• 2019

This paper proposes a multimode hybrid control strategy that can achieve zero-voltage switching of primary switches and zero-current switching of secondary rectifier diodes in a wide input voltage range for full-bridge LLC resonant converters. When the input voltage is lower than the rated voltage, the converter operates in Mode 1 through the variable-frequency control strategy. When the input voltage is higher than the rated voltage, the converter operates in Mode 2 through the VF and phase-shift control strategy until the switching frequency reaches the upper limit. Then, the converter operates in Mode 3 through the constant-frequency and phase-shift control strategy. The secondary-side diode current will operate in the discontinuous current mode in Modes 1 and 3, whereas it will operate in the boundary current mode in Mode 2. The current RMS value and conduction loss can be reduced in Mode 2. A detailed theoretical analysis of the operation principle, the voltage gain characteristics, and the realization method is presented in this paper. Finally, a 500 W prototype with 100-200 V input voltage and 40 V output voltage is built to verify the feasibility of the multimode hybrid control strategy.

• 전기학회논문지P
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• 제51권1호
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• pp.10-17
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• 2002

Due to the development of information communication field, the interest of the SMPS(Switched Mode Power Supply) is increased. The size and weight of SMPS are decided by inductor, capacitor and transformer. Thus, the low loss converter which is operated in high speed switching is required. The resonant FB DC-DC converter is able to operate in high speed switching and apply to high power field because the switching loss is low. In this thesis, it is proposed to control strategy for constant output power of resonant FB DC-DC converter in variable input voltage. The proposed control system is a digital I-PD type control and apply to phase-shift resonant type controller. The output voltage tracks reference without steady state error in variable input voltage. The validity of proposed control strategy is verified from results of simulation and experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.458-463
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• 1997

In this paper, we propose a variable structure control approach for the system with matched and unmatched uncertainty. By using time-varying sliding mode, the reaching mode is removed, and the design methodology represents a realistic design approach with quadratic criterion for systems incorporating both matched and unmatched uncertainties. The criterion contains states and linear part of input for all time. The practical application of the control strategy is presented in the design of a stability augmentation system for an aircraft is presented.

• 한국건설관리학회논문집
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• 제13권5호
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• pp.94-102
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• 2012

최근 글로벌 금융위기, 미분양 주택의 증가 등으로 인해 건설기업의 효율성 분석이 요구되고 있다. 기업에 대한 효율성 분석시 가장 중요한 것은 효율성 측정에 사용된 투입-산출변수이다. 하지만 건설기업의 효율성 분석에 중요한 영향을 미치는 핵심적인 투입-산출변수를 추출하기 위한 체계적인 연구는 미흡하였다. 따라서 본 연구에서는 건설기업의 효율성 분석을 위한 핵심 투입-산출변수를 추출을 위해 투입-산출변수 별로 모든 조합을 제시한 모형을 제시하고 DEA모형과 PCA분석을 통하여 건설기업의 효율성을 분석에 중요한 요소인 투입-산출변수를 추출하고자 한다. 본 연구를 위해 기존 연구 및 이론적 고찰을 하고, 효율성 측정을 위한 변수 및 21개 모형을 설정하였다. 다음으로 효율성 및 PCA분석을 하고 결과를 도출하였다. 연구 결과, 핵심적인 투입 및 산출변수는 2006년의 경우 투입변수는 종업원수, 산출변수는 매출액, 2008년의 경우 투입변수는 자본금, 산출변수는 당기순이익, 2010년의 경우 투입변수는 고정자산, 산출변수는 매출액으로 나타났다. 건설기업 효율성 결과에 중요한 영향을 주는 변수 추출을 통해 개별 건설기업들이 효율성을 향상하기 위한 중점전략을 마련할 수 있을 것으로 판단된다.

• 기술혁신학회지
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• 제14권3호
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• pp.552-577
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• 2011

본 연구는 우리나라 공공 연구기관들의 기술이전과 사업화 과정에 관련된 주요 활동 및 기술이전 사업화 성과에 영향을 미치는 요인들을 도출하고 국내 공공 연구기관의 기술사업화 프로세스에 대한 포괄적인 이해를 도울 수 있는 모형을 제시하였다. 구조방정식을 이용한 공공연구기관의 기술사업화 프로세스 모형은 투입-중간산출역량-산출(성과)의 구조를 적용하여 구성하였다. 선향 연구에서 도출된 이론을 바탕으로 투입 요인으로는 R&D 투입, 기술사업화 전략/지원, 기술사업화협력, 사회적 자본 등을 포함하고, 중간산출역량요인으로 R&D역량을, 산출요인으로 기술사업화 성과 등을 포함하고 있다. 기술사업화 프로세스 모형을 국내 대학 및 공공연구기관을 대상으로 설문조사를 실시하여 회수한 88부와 관련 통계 자료를 활용하여 실증분석하고 결과를 제시하였다. 주요 실증분석 결과를 보면 R&D 투입은 R&D역량에 긍정적인 영향을 미치며 R&D역량은 기술사업화 성과에 영향을 미치는 것으로 나타났다. 그리고 기술사업화 협력과 사회적 지본도 기술사업화 성과에 긍정적인 영향을 주는 것으로 나타났으나 기술사업화 전략 및 지원이 기술사업화 성과에 미치는 영향은 통계적으로 유의하지 않은 것으로 조사되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1351-1353
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• 2000

In this paper, it is proposed to constant power control of solar power system. The solar power system has disadvantage that low power density and variable power output. Proposed strategy is controled by DC/DC converter using phase shift PWM and I-PD type control applying type 1 digital system. The validity of proposed control strategy is verified from simulations results using PSIM.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권3호
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• pp.157-163
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• 2000

In this paper, an Evolving Neural Network Controller(ENNC) which its structure and its connection weights are optimized simultaneously by Real Variable Elitist Genetic Algoithm(RVEGA) was presented for stabilization of an Inverter Pendulum(IP) system with nonlinearity. This proposed ENNC was described by a simple genetic chromosome. And the deletion of neuron, the determinations of input or output neuron, the deleted neuron and the activation functions types are given according to the various flag types. Therefore, the connection weights, its structure and the neuron types in the given ENNC can be optimized by the proposed evolution strategy. Through the simulations, we showed that the finally acquired optimal ENNC was successfully applied to the stabilization control of an IP system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.936-941
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• 2004

An Optimal Feedforward Integral Variable Structure or FIVSC approach for an electrohydraulic position servo control system is presented in this paper. The FIVSC algorithm combines feedforward strategy and integral in the conventional Variable Structure Control (VSC) and calculating the control function to guarantee the existence of a sliding mode. Furthermore, the chattering in the control signal is suppressed by replacing the sign function in the control function with a smoothing function. The simulation results illustrate that the purposed approach gives a significant improvement on the tracking performances when compared with some existing control methods, like the IVSC and MIVSC strategies. Simulation results illustrate that the purposed approach can achieve a zero steady state error for ramp input and has an optimal motion with respect to a quadratic performance index. Moreover, Its can achieve accurate servo tracking in the presence of plant parameter variation and external load disturbances.