• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.618-626
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• 2011

Solar cell is one of the most important new renewable energy for future energy generation. This paper presents a novel two stage DC/DC converter topology for PV PCSs. The proposed converter consists of an interleaved boost converter and a two-tank LLC resonant converter which is connected in parallel in primary and series in secondary. The main idea of this topology is that the system can achieve either unilateral or bilateral operations due to the input voltage level of the PV module, which leads to a better performance. The operating schemes on the proposed converter are analyzed and described. A 2.2kW prototype product is built, tested and verified.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.6
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• pp.44-49
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• 2022

The improvement in the battery performance and life using a battery thermal management system directly affects the improvement in the performance, life, and energy efficiency of electric vehicles. Therefore, this study numerically analyzed the heat exchange processes between the coolant inside the cooling plate channel and the heat generated by the battery. The cooling performance was analyzed based on the average temperature, temperature uniformity, and the maximum and minimum temperature differences of the battery. A performance difference existed depending on the coolant inlet temperature but showed the same tendency of cooling performance according to the shape of each plate's channel. Type 1 showed the best results in terms of battery temperature uniformity, which is the most important measure of battery performance; Type 2 showed the best results in terms of the average temperature of the battery; and Type 3 showed the best results in terms of the maximum and minimum temperature differences of the battery compared with that of the other cooling plates.

• Plant Journal
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• v.18 no.1
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• pp.43-49
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• 2022

In this study, the operational characteristics of the 7.48 MW fuel cell power plant consisting of 17 units of 440 kW Phosphoric Acid Fuel Cell (PAFC) in operation since its commercial operation in December 2017 were explained and the heat recovery process of the plat using Organic Rankine Cycle (ORC)was simulated. The fuel cell system performance improvement and economic assessment were analyzed by calculating the amount of heat recovery and electric power available when connecting a 125 kW XLT Model ORC for hot water heat sources with 105℃, 40.8 t/h. The result of the study shows that integrating the 125 kW ORC to PAFC power plant would improve generating efficiency by about 0.6% through annually 851,472 kWh of electricity produced by ORC, and fuel cell and ORC integrated systems were calculated to have a 0.35% higher Internal Return Ratio and more Net Present Value of 1,249 million KRW than not installing ORC despite installation costs.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.64-72
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• 2017

The performance analysis of the 70 W class LED lighting system suitable for the Middle East environment was performed using the lumped parameter model. The LED light is composed of a heating substrate, a heat pipe, and a heat sink. We divided the LED lights into four objects and applied energy equilibrium to each of them to establish four lumped nonlinear differential equations. The solution of the simultaneous equations was obtained by the Runge-Kutta method. Convective heat transfer coefficients of the lumped model were obtained by multidimensional CFD analysis. As a result of comparison with experiment, it was found that the heating substrate had an error of $1.5^{\circ}C$ and the upper heat sink had an error of $1.8^{\circ}C$ and the relative error was about 0.6 %. Using this model, temperature distribution analysis was performed for normal operating conditions with an ambient temperature of $55^{\circ}C$, with sunlight only, with abnormal operating conditions with sunlight, and without an upper heat sink.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.3
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• pp.326-333
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• 2014

This study was conducted to investigate the fishing efficiency of an improved LED fishing lamp for squids. A total of 31 fishing operations were carried out with six-crew commercial fishing vessel Haengbok-Ho (24 tons) on which 43.2kW LED was installed, along with 14 automatic jigging machines, from October 6 to November 16, 2012. The 19 fishing vessels with Haengbok-Ho were compared with a control subject was 24 tons or 29 tons. A total illuminating power of metal halide (MH) fishing lamps in the control fishing vessel was either 84kW or 120kW. The number of automatic jigging machines in the control vessels was 8-18 and the number of crews engaged for fishing operation was 3-13. Average fuel consumption of LED fishing vessels during fishing operation was 505.1l which led to an average fuel consumption of 42.7l per hour. LED fishing vessel and MH fishing vessel caught on an average 1,946 squids and 2,439 squids, respectively, during the study period. Crews (hand line and hand reel) caught about 2.2 times the automatic jigging machines for LED fishing vessel and about 2.1 times for MH fishing vessel. Meanwhile, catches by the fishing vessels with LED in the combined total number per one line of automatic jigging machine and per crew were 86.6% of that of the control fishing vessel with MH. Also, fishing vessels with LED per automatic jigging machine achieved 71.8% of catches of that with MH fishing lamp. The catches of squids per the fishing vessel with 1W LED fishing lamp were higher by more than 135.5% of that in the fishing vessel with MH, which showed a good fishing performance even with only the use of a LED fishing lamp.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.325-333
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• 2021

A 3 kW grid-tied PV inverter with Gallium nitride high-electron mobility transistor (GaN HEMT) for domestic commercialization was developed using boost converter and full-bridge inverter with LCL filter topology. Recently, many GaN HEMTs are manufactured as surface mount packages because of their lower parasitic inductance characteristic than standard TO (transistor outline) packages. A surface mount packaged GaN HEMT releases heat through either top or bottom cooling method. IGOT60R070D1 is selected as a key power semiconductor because it has a top cooling method and fairly low thermal resistances from junction to ambient. Its characteristics allow the design of a 3 kW inverter without forced convection, thereby providing great advantages in terms of easy maintenance and high reliability. 1EDF5673K is selected as a gate driver because its driving current and negative voltage output characteristics are highly optimized for IGOT60R070D1. An LCL filter with passive damping resistor is applied to attenuate the switching frequency harmonics to the grid-tied operation. The designed LCL filter parameters are validated with PSIM simulation. A prototype of 3 kW PV inverter with GaN HEMT is constructed to verify the performance of the power conversion system. It achieved high power density of 614 W/L and peak power efficiency of 99% for the boost converter and inverter.

• Journal of Drive and Control
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• v.17 no.1
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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.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.4
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• pp.527-536
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• 2014

In this paper, the 50kW aerogenerator which is applicable to the microgrid was designed and analyzed by using commercial simulation program Maxwell 2D. Particularly, the suggested PMSG to reduce the cogging torque introduced the offset and skew concept. The suggested optimal value of offset and skew was decided by 2mm and 60 degree of electric angle. The simulation results of the PMSG when load operation condition showed the average harmonic distortion 1.3%, voltage 322.41V, current 94.95A, and iron loss 9.73W, eddy current loss 73.68W, copper loss 3.52kW. The capacity of aerogenerator calculated 61.56kW, and the suggested design process can be applied to higher capacity generator.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.293-300
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• 2006

KIER has been developing a Ru-based preferential oxidation catalysts and a novel fuel processing system to provide hydrogen rich gas to residential PEMFCs system. The catalytic activity of Ru-based catalysts was investigated at different Ru loading amount and different support structure. The obtained result indicated that 2 wt% loaded Ru-based catalyst supported on ${\alpha}-Al_2O_3$ showed high activity in low temperature range and suppressed the methanation reaction. The developed prototype fuel processor showed thermal efficiency of 78% as a HHV basis with methane conversion of 92%. CO concentration below 10 ppm in the produced gas is achieved with separate preferential oxidation unit under the condition of $[O_2]/[CO]=2.0$. The partial load operation have been carried out to test the performance of fuel processor from 40% to 80% load, showing stable methane conversion and CO concentration below 10 ppm. The durability test for the daily start-stop and 8 h operation procedure is under investigation and shows no deterioration of its performance after 50 start-stop cycles. In addition to the system design and development.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.200-207
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• 1993

A methanol reformer was designed and fabricated using a CuO-ZnO low temperature shift catalyst, and its operation characteristics have been studied for the phosphoric acid fuel cell (PAFC) power generation system. The type of reactor was annular Methanol was consumed both for heating and for reforming fuel. Contents of carbon monoxide produced from the reformer increased as the reaction temperatures increased, but decreased as the mole ratios of water to methanol(H$_2$O/CH$_3$OH) increased. At steady state operating conditional, temperature profile of the catalytic reactor of the reformer was well coincide with the model equation, and it took 50 minutes from start to the rated condition of the reformer. When the system was operated at 4/4 and 1/4 of load, thermal efficiencies of the system were 72.3% and 77%, respectively. When the PAFC system was operated with reformed gas in the range of 62 V-37.6 V and 0-147 A, the trend of I-V curve showed a typical fuel tell characteristic. At steady state condition, the flow rates of reforming and combustion methanol were 88.1 mol/h and 50.1 mol/h, respectively.