• 전기학회논문지P
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• 제67권4호
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• pp.175-182
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• 2018

In recent years, micro-grid has been widely focused on the fields of renewal energy systems. This paper proposes a novel robust power converter control against arbitrary electric load changes for islanded micro-grid topology. First, we provide a state-space representation of our micro-grid model including power converter and electric load circuit. And then a state feedback control method is applied to construct a nominal control framework. Next, we propose a robust adaptive control law to enhance a control performance against unexpected load perturbation. In addition, we analytically investigate a passivity property for the micro-grid model and carry out computer simulation to demonstrate superiority and reliability of the proposed control methodology.

• Journal of Power Electronics
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• 제13권3호
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• pp.400-408
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• 2013

This paper presents a discrete state-space controller using state feedback control and feed-forward decoupling to provide a desirable control bandwidth and control stability for dynamic voltage restorers (DVR). The paper initially discusses three typical applications of a DVR. The load-side capacitor DVR topology is preferred because of its better filtering capability. The proposed DVR controller offers almost full controllability because of the multi-feedback of state variables, including one-beat delay feedback. Feed-forward decoupling is usually employed to prevent disturbances of the load current and source voltage. Directly obtaining the feed-forward paths of the load current and source voltage in the discrete domain is a complicated process. Fortunately, the full feed-forward decoupling strategy can be easily applied to the discrete state-space controller by means of continuous transformation. Simulation and experimental results from a digital signal processor-based system are included to support theoretical analysis.

• 한국전기전자재료학회논문지
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• 제29권5호
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• pp.274-278
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• 2016

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 20 piezoelectric materials. This study attempted to evaluate output depending on pavement materials when paving road piezoelectric energy harvester in the road. Harvester is the bender type and is the method of supporting the both ends of piezoelectric material and applying the load in the middle part. Harvester was paved in the type paved with asphalt, type paved with cement and in the exposed type not covering the top of harvester. The output characteristics were compared and evaluated depending on changes in vehicle load and vehicle speed changes. As vehicles, truck (11.9 ton), SUV(1.6 ton) and sedan (1.5 ton) were used and the output characteristics when driving at the interval of 10 km/h from 10 km/h to 100 km/h were evaluated.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.524-527
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• 2004

New concept of hybrid divisible load theory is introduced in this paper. Hybrid system deals with a combination of modularly divisible load and arbitrarily divisible load. Main idea of hybrid divisible load theory is introduced with a simple example. A condition of optimality is derived for the hybrid case.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2004년도 하계학술대회
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• pp.338-341
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• 2004

New concept of hybrid divisible load theory is introduced in this paper. Hybrid system deals with a combination of modularly divisible load and arbitrarily divisible load. Main idea of hybrid divisible load theory is introduced with a simple example. A condition of optimality is derived for the hybrid case.

• 전기학회논문지
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• 제63권5호
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• pp.644-651
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• 2014

The renewable energy system and the real-time pricing can provide the significant economic advantage for end-user of residential house. However, according to recent studies, high initial cost of renewable energy system such as photovoltaic (PV) system and lack of suitable load control methods adjusting electric power consumption in response to time-varying price are regarded as the major obstruction for introduction of renewable energy system and real-time pricing in residental household. In this paper, we propose automated optimal load control strategy which aim to achieve not only minimizing the electricity cost but also the increase in the utilization rates of PV generation power of residential PV house in real-time pricing environment. Simulation results show that our proposed optimal load control strategy leads to significant reduction in the electricity costs and increase in the utilization rates of power generated by PV system in comparison with the conventional PV house. Therefore, the proposed optimal load control strategy can provide more economic benefit to end-user.

• 조명전기설비학회논문지
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• 제26권10호
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• pp.81-88
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• 2012

Surge protective devices(SPDs) are widely used as a most effective means protecting the electrical and electronic equipment against overvoltages such as lightning and switching surges. When installing SPDs, it is essential that the voltage protection level provided by SPDs should be lower than the withstand voltage of the equipment being protected. But even the proper selection of SPDs are achieved, the voltage at the equipment terminal may be higher than the residual voltage of SPD due to the reflection and oscillation phenomena. This paper was focused on the investigations of the conditions for which the equipment is protected by an SPD taking into account the influences of the protective distance and type of load. The protective effects of SPD with voltage-limiting component were analyzed as functions of types of load and protective distance between the SPD and load. As a result, in the cases of long protective distances, capacitive loads and loads with high resistance, the voltage at the load terminal was significantly higher than the residual voltage of SPD. It was found that the proper installation of SPDs should be carried out by taking into account the protective distance and type of load to achieve reliable protection of electronic equipments against surges.

• 한국전기전자재료학회논문지
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• 제34권4호
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• pp.242-245
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• 2021

In this work, we fabricated oxide on an n-type silicon substrate through local anodic oxidation (LAO) using atomic force microscopy (AFM). The resulting oxide thickness was measured and its correlation with load force, scan speed and applied voltage was analyzed. The surface oxide layer was stripped using a buffered oxide etch. Ohmic contacts were created by applying silver paste on the silicon substrate back face. LAO was performed at approximately 70% humidity. The oxide thickness increased with increasing the load force, the voltage, and reducing the scan speed. We confirmed that LAO/AFM can be used to create both lateral and, to some extent, vertical shapes and patterns, as previously shown in the literature.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.23-26
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• 2005

This paper presents the load balance of Mobile IP in wireless systems. Mobile IP can support wireless users with continuous network connections while changing locations. If a failure occurs in a mobility agent, the wireless users located in the coverage area of the fault mobility agent will lose their network connections. To tolerate the failure of mobility agents, this paper proposes the method of an efficient approach to reduce severe overload.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.359-359
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• 2010

IGBT(Insulated Gate Bipolar Transistor) 란 MOS(Metal Oxide Silicon) 와 Bipolar 기술의 결정체로 낮은 순방향 손실(Low Saturation)과 빠른 Speed를 특징으로 기존의 Thyristor, BJT, MOSFET 등으로 실현 불가능한 분양의 응용처를 대상으로 적용이 확대 되고 있고, 300V 이상의 High Power Application 영역에서 널리 사용되고 있는 고효율, 고속의 전력 시스템에 있어서 필수적으로 이용되는 Power Device이다. IGBT는 출력 특성 면에서 Bipolar Transistor 이상의 전류 능력을 가지고 있고 입력 특성 면에서 MOSFET과 같이 Gate 구동 특성을 갖기 때문에 High Switching, High Power에 적용이 가능한 소자이다. 반면에, Conventional IGBT는 MOSFET과 달리 IGBT 내부에 Anti-Parallel Diode가 없기 때문에 Inductive Load Application 적용시에는 별도의 Free Wheeling Diode가 필요하다. 그래서, 본 논문에서 별도의 Anti-Parallel Diode의 추가 없이도 Inductive Load Application에 적용 가능한 RC IGBT를 적용하여 600V/15A급 Three Phase Inverter Module을 제안 하고자 한다.