• Journal of Power Electronics
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• 제16권4호
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• pp.1494-1503
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• 2016

Power quality promotion has received increasing attention because of the wide use of semiconductor devices in recent decades. Reactive power regulation is crucial to ensuring the stable operation of power systems. In this study, a continuous reactive power controller, which is referred to as a parallel-connected magnetic energy recovery switch (MERS), is developed to regulate voltage or power factor in power grids. First, the operating principle is introduced, and a mathematical model is built. Second, a new control method for restraining current harmonics and the peak voltages of capacitors is presented. Using the proposed method, the MERS shows a wide range in terms of reactive power compensation. Finally, the performance of the proposed controller is demonstrated through computer simulations and experiments. Unlike STATCOMs, the proposed controller entails low losses, adopts a small dc capacitor, and offers ease of use.

• STI Policy Review
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• 제1권3호
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• pp.1-15
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• 2010

This paper makes the case that a new policy strategy to enhance a global green recovery is needed urgently. The new strategy requires two essential elements. First, G20 economies should follow the lead of South Korea and China and turn their green stimulus investments into a serious long-term commitment, and to support these investments, they should adopt environmental pricing policies and instigate pricing and regulatory reforms to reduce carbon dependency. Second, the G20 also needs to target and coordinate assistance to developing economies in science, technology and innovation (STI) for clean energy. Such assistance is essential to help developing economies to overcome the skills, technological and capital gap that they face in clean energy technologies over the long term. Reform of the Clean Development Mechanism (CDM) is also necessary to establish a long-term global price signal for carbon, and to increase the coverage of developing economies, the sectors and technologies and the overall financing of clean energy projects. Formulating such a policy strategy should appeal to both the Asian-Pacific and Western economies comprising the G20, and by working together to formulate such a strategy, the G20 could lead the way toward a new era of global economic management and STI cooperation in clean energy.

• 상하수도학회지
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• 제29권1호
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• pp.57-63
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• 2015

Recently, Korea's municipal wastewater treatment plants generated amount of wastewater sludge per day. However, ocean dumping of sewage sludge has been prohibited since 2012 by the London dumping convention and protocol and thus removal or treatment of wastewater sludge from field sites is an important issue on the ground site. The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade sewage sludge to produce solid fuel with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading fuel properties and increased materials and energy recovery, which is conducted at temperatures ranging from 200 to $350^{\circ}C$ with a reaction time of 30 min. Hydrothermal carbonization increased the heating value though the increase of the carbon and fixed carbon content of solid fuel due to dehydration and decarboxylation reaction. Therefore, after the hydrothermal carbonization, the H/C and O/C ratios decreased because of the chemical conversion. Energy retention efficiency suggest that the optimum temperature of hydrothermal carbonization to produce more energy-rich solid fuel is approximately $200^{\circ}C$.

• 한국자동차공학회논문집
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• 제20권2호
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• pp.21-29
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• 2012

A dual loop waste heat recovery system with Rankine steam cycles for the improvement of fuel efficiency of gasoline vehicles has been investigated. A high temperature loop (HT loop) only recovers the heat of the exhaust gas. A low temperature loop (LT loop) recovers the residual heat from the HT loop, the coolant heat and the remaining exhaust gas heat. The two separate loops are coupled with a heat exchanger. This paper has dealt with a layout of the dual loop system, the review of the working fluids, and the design of the cycle. The design point and the target heat recovery of the HT boiler, a core part of a HT loop, have been presented. The prototype of the HT boiler was evaluated by experiment. For the performance evaluation of the HT boiler, inlet temperature of the HT boiler working fluid was set equal to the temperature degree of sub-cool of $5^{\circ}C$ at the condensing pressure. The exit condition was the degree of super-heat set at $5^{\circ}C$. The characteristics of the HT boiler such as heat recovery and pressure drops of fluids were evaluated with varying flow rates and inlet temperatures of exhaust gas under various evaporating pressure conditions.

• 한국해양환경ㆍ에너지학회지
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• 제6권4호
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• pp.52-66
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• 2003

본 연구에서는 물리, 기계적인 누유 제거방법으로서 부착식의 일종인 드럼식 유회수기를 사용하여 회수조건의 변화에 따른 유회수율을 실험적으로 구하였다. 일반적으로 기계적인 유회수방법에서 문제시되는 것은 고점도 유체에서 유회수가 어렵고, 얇은 유막층에서 회수유중물의 함량이 증가하며, 유회수율이 크게 감소되는 점이다 본 연구에서는 드럼식 유회수기를 이용하여 드럼의 잠긴 깊이에 따른 접촉각, 이송속도, 유막두께 등의 유회수 조건이 유회수율에 미치는 영향을 디젤유를 사용하여 구하고 이를 분석하여 효과적인 유회수 조건을 구하였다. 실험결과 드럼식 유회수기에서 유회수율은 부착유량과 부착유량의 이탈손실에 의하여 영향을 받으며, 부착유량은 잠긴 깊이에 의한 접촉각에 영향을 받는다. 드럼식 유회수기에서의 유회수율은 드럼의 지름에 대한 잠긴 깊이의 비 h/d=0.15(접촉각 45°)에서 가장 효가적인 유회수율을 보이며, 얇은 유막두께에서도 비교적 효과적인 유회수율과 회수효율을 보였다. 또한 이송속도는 최대양정유량을 보이는 임계이송속도를 갖으며, 임계이송속도는 유막두께의 증가에 따라 증가한다.

• 자원리싸이클링
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• 제31권4호
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• pp.34-39
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• 2022

본 연구에서는 약 3.5% 구리 함유 폐에칭액으로부터 구리를 회수하기 위한 철 샘플에 따른 시멘테이션 반응 시 초음파 에너지 인가에 의한 반응 속도와 구리 회수율에 미치는 영향을 조사하였다. 그 결과 단순 교반 공정에 비해 시멘테이션 반응이 효과적으로 일어나 같은 시간 대비 높은 구리 회수율을 나타냈다. 단순 교반과 초음파에너지를 가하였을 때를 비교해보면, 25분 반응에 따라 철 샘플 형태가 plate를 사용하였을 때, 약 9.5%가 56.6%로 향상되었으며, chip은 약 14.0%에서 46.1%, powder는 약 41.9%에서 77.2%로 증가하였다. 이는 시멘테이션 반응으로 생성되어 철 표면을 덮고 있던 구리가 탈착되며 연속반응이 유도되었고, 구리 회수율은 약 2배에서 6배까지 증가하였으며, 회수된 구리의 입자 크기 또한 감소하는 경향을 확인할 수 있었다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
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• pp.277-278
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• 2017

• Journal of Power Electronics
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• 제9권5호
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• pp.809-821
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• 2009

This paper proposes a new phase-shift full-bridge DC-DC converter by applying energy recovery circuits to a conventional full-bridge DC-DC converter in plasma display panel applications. The converter can achieve soft-switching in main-switches by an extra auxiliary resonant network even with the wide operating condition of both output load and input voltage. The un-coupled design guidelines to the main bridge-leg component parameters for soft-switching operation contribute to conduction loss reduction in the transformer primary side leading to efficiency improvement. The auxiliary switches in the resonant network also operate in zero-current switching. This paper analyzes the operation modes of the proposed scheme and presents the key design guidelines through steady state analysis. Also, the paper verifies the validity of the circuits by hardware experiments with a 1kW DC/DC converter prototype.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.544-546
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• 2008

An improved dual-path energy recovery circuit (ERC) using a current source and a voltage source for plasma display panel (PDP) is proposed. The proposed ERC uses the voltage source to charge a panel and the current source to discharge the panel. Thus, the proposed circuit can make the panel charge to $V_S$ and discharge to 0V, fully and it is possible to achieve zero voltage switching (ZVS) of all switches in H-bridge inverter and zero current switching (ZCS) of all switches in the ERC. Moreover, it has less conduction and switching loss in ERC devices by the dual energy recovery paths for charging and discharging the panel. Furthermore, it has features of canceling the gas discharge current, high performance and the low cost ERC components. The operation principle and features of the proposed ERC are presented in detail and verified with 42-inch SD PDP.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.256-259
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• 2006

Comparison of one two-path single energy recovery circuit for plasma display panel (PDP) is shown in this paper. A single energy recovery circuit (SERC) is proposed to reduce cost for manufacturing PDP and there are two ways, one and two-path, in driving this circuit. Compared with one-path SERC, there are low power consumption, low surge current and high performance in two-path SERC. The results will be shown with 42-inch HD panel.