• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1034-1038
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• 1995

The purpose of this study is to research and develop $TiS_2$ composite cathode for lithium polymer battery(LPB). $TiS_2$ electrode represent a class of insertion positive electrode used in Li secondary batteries. In this study, we investigated preparation of $TiS_2$ composite cathode and AC impedance response of $TiS_2$ composite/SPE/Li cells as a function of state of charge(SOC) and cycling. The resistance of B type cell using $TiS_2PEO_8LiClO_4PC_5EC_5$ composite cathode was lower than that of A type cell using $TiS_2PEO$ composite cathode. The cell resistance of B type cell is high for the first few percent discharge, decreases for midium discharge and then increases again toward the end of discharge. We believe the magnitude of the cell resistance is dominated by passivation layer impedance and small cathode resistance. AC impedance results indicate that the cell internal resistance increase with cycling, and this is attributed to change of passivation layer impedance with cycling. The passivation layer resistance($R_f$) of B type cell decreases for the 2nd cycling and then increases again with cycling. Redox coulombic efficiency of B type cell was about 141% at 1st cycle and 100% at 12th cycle. Also, $TiS_2$ specific capacity was 115 mAh/g at 12 cycle.

• 한국지열·수열에너지학회논문집
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• 제18권3호
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• pp.7-18
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• 2022

Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△H_TNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

• 드라이브 ㆍ 컨트롤
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• 제17권1호
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• pp.27-36
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• 2020

The aim of this study is to design a simulation model for an electric All-Wheel-Drive (AWD) tractor to evaluate the performance of the selected component and agricultural work ability. The electric AWD tractor consists of four motors independently for each drive wheel, and each motor is combined with an engine generator, a battery pack, and reducers. The torque data of a 78 kW-class tractor was measured during plow tillage and driving operation to develop a workload cycle. A simulation model was developed by using commercial software, Simulation X, and it used the workload as the simulation condition. As a result of simulation analysis, the drive system, including an electric motor and reducers, was able to cope with high load during plow tillage. The SOC (State of Charge) level was influenced by the output power of the motor, and it was maintained in the range of 50~80%. The fuel consumed by the engine was about 18.23 L during working on a total of 8 fields. The electric AWD tractor was able to perform agricultural work for about 7 hours. In the future study, the electric AWD tractor will be developed reflecting the simulation condition. Research on the comparison between the simulation model and the electric AWD tractor should be performed.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.46-51
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• 2012

Fuel Cell Hybrid Vehicles (FCHVs) have become a major topic of interest in the automotive industry owing to recent energy supply and environmental problems. Several types of power management strategies have been developed to improve the fuel economy of FCHVs including optimal control strategy based on optimal control theory, rule-based strategy, and equivalent consumption minimization strategy (ECMS). The ECMS is applied in this study. This strategy is based on the heuristic concept that the usage of the electric energy can be exchanged to equivalent fuel consumption. This strategy is known as one of the promising solutions for real-time control of hybrid vehicles. The ECMS for an FCHV is introduced in this paper as well as the equivalent fuel consumption parameter. The relationship between the battery final state of charge (SOC) and the fuel consumption while changing the equivalent fuel consumption parameter is obtained for three different driving cycles. The function of the equivalent fuel consumption parameter is also discussed.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5357-5365
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• 2013

본 논문은 ASM(Automotive Simulation Model)을 기반으로 한 전기 트랙터 구동 시스템의 모델링을 실시하였다. 실제 전기 트랙터를 개발하기 전에 트랙터 구동 시스템 요소 각각의 사양에 대한 정의는 필수적이다. 트랙터는 차량과 달리 주행과 작업을 동시에 수행하기 때문에 2개의 PMSM을 효율적으로 운용할 필요가 있다. 따라서 본 연구에서는 Simulink를 기반으로 한 ASM과 Carsim을 활용하여 전기 트랙터 구동 시스템을 연구하였다. 전기 트랙터 구동시스템의 검증을 위해 시뮬레이션과 실차 테스트를 실시하여 각각에 대한 최대 출력, SOC, 주행가능거리, 최대속도를 측정 및 비교 하였다. 시뮬레이션 연구를 통해 트랙터 전반적인 동적 특성에 대한 선행 연구 기반을 마련하였으며 전기 구동 시스템에 대한 설계가이드라인을 제시할 수 있었다.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.65-72
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• 2006

In new generation vehicle technologies, a fuel cell vehicle becomes more important, by virtue of their emission merits. In addition, a fuel cell is considered as a major source to generate the electricity for vehicles in near future. This paper focuses on modeling of not only an electric vehicle and but also a fuel cell vehicle to estimate performances. And an EV cart is manufactured to verify the modeling. Speed, voltage, and current of the vehicle and modeling are compared to estimate them at acceleration test and driving mode test. The estimations are also compared with the data of the Ballard Nexa fuel cell stack. In order to investigate a fuel cell based vehicle, motor and fuel cell models are integrated in a electric vehicle model. The characteristics of individual components are also integrated. Calculated fuel cell equations show good agreements with test results. In the fuel cell vehicle simulation, maximum speed and hydrogen fuel consumption are estimated. Even though there is no experimental data from vehicle tests, the vehicle simulation showed physically-acceptable vehicle characteristics.

• 한국인터넷방송통신학회논문지
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• 제17권5호
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• pp.199-208
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• 2017

리튬 폴리머 배터리는 높은 안전성, 빠른 충전 및 긴 라이프 사이클 등으로 인해 에너지 저장치(ESS: Energy Storage System), 전기자동차(EVs: Electric Vehicles)등에 채택이 되어 사용되고 있으며, 그리고 현재는 농업용 드론에서 까지 사용이 되고 있다. 그러나 리튬 폴리머 배터리는 과충 방전에는 리튬-이온 배터리 내의 격차구조가 파괴되어 배터리 수명이 줄어들게 되며, 과충 방전을 방지하기 위해 불균등한 셀 전압을 균등 제어 할 수 있는 셀 밸런싱 시스템이 필수적이다. 본 논문은 각 셀의 충 방전할때의 전압차이를 검출하여 불균형된 셀을 확인하여 비선형 시스템에 적합한 퍼지 제어기를 개발하여 적용한 셀별 밸런싱 알고리즘을 제안한다. 본 논문은 농업용 드론의 배터리팩의 셀 밸런싱을 퍼지제어를 하여 셀 간 균등 제어를 위해 설계하였으며, 최종 결과로 셀 간 밸런싱이 잘 되는지 확인하고 자 셀이 2개 있을 때와 6개 그리고 최종적으로 12개의 각 셀 밸런싱이 되는지를 확인하였다. 이는 다른 제품에도 사용할 수 있는지를 실험하고자 하였으며, 확인결과 사용된 셀의 개수와는 관계없이 셀별 밸런싱이 잘 되고 있음을 확인하였다.

• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.33-38
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• 2015

시간대별 효율적인 전력 운영과 전력품질 향상을 위해 ESS (Energy Storage System)의 보급이 세계적으로 활발하게 이루어지고 있다. 이러한 ESS용 전원소자로 리튬이차전지의 채용이 급격히 늘어남에 따라, 리튬이차전지의 수명 및 출력 열화 거동을 측정 및 예측하는 기술이 시급히 요구되고 있다. 특히, ESS 운영에 있어 핵심 특성인 리튬이차 전지 출력은 측정이 어려울 뿐만 아니라, 정확한 측정을 위해서는 많은 시간이 소요되는 문제점이 있다. 따라서, 본 연구에서는 ESS용 리튬이차전지 단전지를 전산 모델링 한 후, 펄스 측정법을 적용하여 충전상태에 따른 방전 및 충전시의 직류저항(DC-IR)과 출력을 예측한다. 또한, 두 가지 펄스 측정법인 HPPC (Hybrid Pulse Power Characteristics)와 J-Pulse (JEVS D 713, Japan Electric Vehicle Association Standards)의 결과를 비교 분석한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.104-104
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• 2011

The fuel economy estimates essentially serve two purposes : to provide consumers with a basis on which to compare the fuel economy of different vehicles, and to provide consumers with a reasonable estimate of the range of fuel economy they can expect to achieve. The current fuel economy label values utilize measured fuel economy over city driving cycles. However, this test driving mode can not be evaluated the variety factor of the real-world. These factors include differences between the way vehicles are driven on the road and over the test cycles, air conditioning use, widely varying ambient temperature and humidity, widely varying trip lengths, wind, precipitation, rough road conditions, hills, etc. The purpose of this paper is to account for three of these factors on the fuel economy : 1) on-road driving patterns (i.e. higher speeds and more aggressive driving (higher acceleration rates)), 2) air conditioning, and 3) colder temperatures. The new test methods will bring into the fuel economy estimates the test results from the five emissions tests in place today : CVS-75, HWFET, US06, SC03 and Cold CVS-75. Based on these new test methods, this paper discusses the characteristics of driving condition on Hybrid electric vehicle (HEV). And this paper assesses the fuel economy label of HEV.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1442-1448
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• 2017

Recently, electric power systems have been operating with tight margins and have reached their operational limits. Many researchers consider a microgrid as one of the best solutions to relieve that problem. The microgrid is generally powered by renewable energies that are connected through power converters. In contrast to the rotational machines in the conventional power plants, the converters do not have physical rotors, and therefore they do not have rotational inertia. Consequently, a stand-alone microgrid has no inertia when it is powered by the only converter-based-generators (CBGs). As a result, the relationship between power and frequency is not valid, and the grid frequency cannot represent the power balance between the generator and load. In this paper, a superconducting flywheel energy storage system (SFESS) is applied to an inertia-free stand-alone (IFSA) microgrid. The SFESS accelerates or decelerates its rotational speed by storing or releasing power, respectively, based on its rotational inertia. Then, power in the IFSA microgrid can be balanced by measuring the rotor speed in the SFESS. This method does not have an error accumulation problem, which must be considered for the state of charge (SOC) estimation in the battery energy storage system (BESS). The performance of the proposed method is verified by an electromagnetic transient (EMT) simulation.