• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.349-352
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• 2008

The most concerning issue in these days is the energy crisis by increasing threat of global warming and depletion of natural resources. In the situations, the Plug-in Hybrid Electric Vehicle (PHEV) is drawing attention from many countries for the next generation's car which has higher fuel efficiency and lower environmental impact. This paper presents simulation results about the limit capacity of central power-grid which doesn't have enough surplus electric power for charging PHEVs. Therefore, this paper also presents a smart charging system that can charge the PHEVs with a function of distributing demands of charging. The smart charging system is an agent facility between the government and consumer, which can recommend the best time to charge the battery of PHEVs by the lowest energy cost. This function of choosing time-slots is the technical system for the government which wants to control the consumption rate of electric power for PHEVs. Finally, this paper presents the economic feasibility of PHEVs from the two kinds of price system, midnight electric price and home electric price.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.836-845
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• 2007

In DC 1500V electric traction substations, diode rectifiers are commonly used to supply stable DC power with electric train sets. However, it operates in the first quadrant of the voltage-current plane and thus needs regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul line 2 and Kwangju line 1. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power for four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy.

• 대한전기학회논문지:전력기술부문A
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• 제52권10호
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• pp.616-623
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• 2003

Competition among electric generation companies is a major goal of restructuring in the electricity industry, The trading system in an electricity market has been one of the most important issues in deregulated electricity market. This paper deals with comparisons of the major two types of the trading system: compulsory pool market and bilateral contract market. The two trading systems are compared quantitatively from the viewpoint of consumer's surplus and social welfare, This paper, also, proposes a unified model of Cournot and Bertrand for analyzing the mixed trading system of pool market and bilateral contract market. Nash equilibrium of the unified model is derived by criteria for participating in bilateral contract market. Numerical results from a sample case show that a mixed trading system of pool market and price-competitive bilateral market is beneficial to consumer from the view points of consumer's surplus.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.852-857
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• 2007

For electric traction using a large power converter, harmonic problem in the p-ower quality and regenerating energy in side of efficiency are important. Recently, by advance in power electronics technology, some countries are considering regenerative inverter from the points of view. when the electric tractions are stopped or driven through the falling slope way, it is very useful to supply surplus energy to the power source by regenerating system in the efficient side of energy and it is very economical. these regenerating energy are supported electrical equipment through DC line. In this research, the purposes are suppressing extra DC-line voltage and saving energy generated while electric traction is been driving on the falling slope way or reducing speed for railway using a 1500V DC-voltage. Besides, the accompanied defects of current distortion, low power factor and the voltage unbalance will be solved by developing the algorism of inverter having ability to compensate current harmonic.

• 전력전자학회논문지
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• 제26권5호
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• pp.334-341
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• 2021

Operation modes and control strategies for single-phase mobility charging station utilizing photovoltaic (PV) generation and energy storage systems (ESS) are proposed. This approach generates electric power from PV to transmit the mobility, ESS, and then transfer it to the grid when surplus electric power is generated during daytime. However, the PV power cannot be generated during night-time, and ESS and the mobility system can be charged using grid power. The power balance control based on power fluctuations and the resonant current control that can compensate harmonic components have been added to increase the stability of the system. The MATLAB/Simulink simulation was carried out to verify the proposed control method, and the 2-kW single-phase grid-tied PV-ESS smart mobility charger was built and tested.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.54-56
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• 2005

The paper proposes the solar photovoltaic power generation system method for photovoltaic system to solve the power shortage due the sudden power demand. So that supplied electric power to system at appearance during surplus electric power minute and unit moment link driving with common use system is available, digital PLL circuit system voltage through composition and phase of solar photovoltatic power generation system to do synchronization do. Feed forward controller was applied to get fast current response Solar cell that is changed by solar radiation always kept the maximum output when it used Step up chopper. The dynamic character had checked through simulation used Matlab Sumulink and confirmed through an experiment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1473-1478
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• 2007

In the respect of energy saving and reusing, it is necessary to reduce greenhouse gases emission and to enhance the operation efficiency in electric railway system. Recently, as the power electronics technologies are advanced, some countries have focused on the regenerative inverter to use regeneration energy on each line. When the electric tractions are stopped or slowed down, it is useful to supply the surplus energy to the power source by regenerative system, which increases its energy efficiency. Also, the generated energy can be supply to other tractions or equipments inside traction. Thus, it may help reduce construction cost of additional power plants. The purpose of this study is to describe the development status of the regenerative inverter system which suppress extra DC-line voltage and regenerate the energy instead of using a resister.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.379-381
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• 2000

In the new electric industry, many of generators and consumers exist in competitive market and electric price is determined by the response of suppliers and consumers. Power supply and consumption make change the electric price and social welfare depends on the elasticity that indicates sensitivity to changes of price related on the electric demand or supply. If elasticity is changed, social welfare that represents the sum of producers and customers surplus will be changed together. This paper investigates the change of the social welfare depending on the elasticity, and presents the propriety of competitive electric market.

• Journal of Electrochemical Science and Technology
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• 제10권3호
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• pp.302-312
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• 2019

The voltage produced from the salinity gradient in reverse electrodialysis (RED) increases proportionally with the number of cell pairs of alternating cation and anion exchange membranes. Large-scale RED systems consisting of hundreds of cell pairs exhibit high voltage of more than 10 V, which is sufficient to utilize water electrolysis as the electrode reaction even though there is no specific strategy for minimizing the overpotential of water electrolysis. Moreover, hydrogen gas can be simultaneously obtained as surplus energy from the electrochemical reduction of water at the cathode if the RED system is equipped with proper venting and collecting facilities. Therefore, RED-driven water electrolysis system can be a promising solution not only for sustainable electric power but also for eco-friendly hydrogen production with high purity without $CO_2$ emission. The RED system in this study includes a high membrane voltage from more than 50 cells, neutral-pH water as the electrolyte, and an artificial NaCl solution as the feed water, which are more universal, economical, and eco-friendly conditions than previous studies on RED with hydrogen production. We measure the amount of hydrogen produced at maximum power of the RED system using a batch-type electrode chamber with a gas bag and evaluate the interrelation between the electric power and hydrogen energy with varied cell pairs. A hydrogen production rate of $1.1{\times}10^{-4}mol\;cm^{-2}h^{-1}$ is obtained, which is larger than previously reported values for RED system with simultaneous hydrogen production.

• 한국건설순환자원학회논문집
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• 제5권3호
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• pp.84-93
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• 2010

지중전력선과 같은 원형 지하매설관의 경우 관의 하단부 다짐효율이 낮아 파손등과 같은 구조적 문제점에 항상 노출되어 있다. 이러한 문제점들 때문에 다양한 방법들이 강구되어 왔으며 그중 하나가 유동성이 뛰어난 저강도 콘크리트의 개발이다. 외국에서는 이미 오래전부터 연구개발을 진행하여 전력회사를 중심으로 이미 실용화 단계에와 있다. 하지만, 국내에서는 일반구조물에 대한 연구는 진행되었으나, 야간시간대 급속시공이 필요한 지중전력선 공사에 적용되는 급결 유동성 뒤채움재에 대한 연구는 최근에 이루어지기 시작했다. 본 논문에서는 고유동성을 지니고 급속 고화가 가능한 현장 굴착토를 활용한 유동성 뒤채움재에 대한 역학적 특성 및 3차례에 걸쳐서 실내모형 및 실물실험을 수행한 결과, 유동성은 교반시작 이후 약 9~15분내 타설 한계 유동성(160 mm)에 도달하는 것으로 확인되었고, 재료의 부력은 타설 초기에 급격히 발생하고 이후 점차 소산하는 것으로 확인되었으며, 그 값은 재료의 단위중량으로 계산한 이론부력의 약 70 %로 계측되었다. 본 연구에서 실험을 통해서 도출한 시공방법(배치플랜트를 이용한 타설, 스페이서 설치간격 1.8 m 및 타설 간격 2 m)을 적용시 시공품질, 작업성 및 구조적 안정성을 확보 할 수 있었다.