• 전기학회논문지
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• 제65권12호
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• pp.1958-1964
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• 2016

AC railway feeding system use single phase to supply power to the railway vehicles. And the system use the rail track as a return current path, so that current flows in the rail. In this situation inductive interference on communication system and unsafe environment can appear on railway system. Therefore knowing the current distribution of catenary system and analysing the return current is required. In this study detail return current distribution was analyzed by modeling the catenary system as 4-conductors group. The distribution characteristics and trends of return current were studied by using the PSCAD/EMTDC and FDTD method that based on Maxwell equation was used to calculate the induced voltage. Simulation code was made by MATLAB. Using this study result data, we can suggest the proper installation location of digital device and these data can be used for additional studies related to return current or induced voltage as a base data.

• 수산해양교육연구
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• 제29권2호
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• pp.570-580
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• 2017

In this study, we designed a fishing system to reproduce the underwater movement of the living Sword tip squid (Loligo edulis) used as bait in the red seabream long line fishery, and conducted the experiment of the fishing operation in 2 ways, i.e., a pole and line fishing method (fishermen) and a bait control fishing system used at fishing sites. Based on the catches in fishing operation, the experiment was conducted over a six times (2014 & 2015), and then 107 fishes were caught by the line fishing method while 57 fishes were caught by the bait control fishing system. The fishermen method actively controlled the speed of gear movement upward and downward while checking the reaction of red seabreams to the bite in the process which a jerk was transmitted to single line hook fishing gear manually. The bait control fishing system is a passive method which fishermen visually check only the movements at the end of fishing pole, enabled differentiation of bite reactions of red seabream during fishing operation. Thus, the difference between fishermen method and the bait control fishing system was found to about 53.3% in the catches. We confirmed the possibility of a site fishing operation based on the bait control fishing system designed newly as a result of this study. Improvement is in several areas for commercialization at the site. This fishing system is expected to be able to find wide-ranging applications as a new labor-saving method for the fishing red seabreams if it is applied to the fishing sites after aforesaid process.

• Preventive Nutrition and Food Science
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• 제1권2호
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• pp.214-219
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• 1996

This study was done to investigate effects of n-s fatty acids and vitamin E supplement on the preneoplastic hepatic enzyme altered foci and cholesterol metabolism in experimental hepatocarcinogenesis system. Weaning male Sprague-Dawley rats were fed the diet containing either 15% corn oil(CO) or sardine oil(SO) with or without vitamin E 800IU supplementation for 12 weeks. After two weeks of feeding, rats were intraper-itoneally injected with a single dose of diethylnitrosamine(DEN:200mg/kg, BW). At the 4th week, rats were given the diet containing 0.02% acetylaminofluorene(AAF) for next 4 weeks. At the 6th Week, 0.05% pheno-barbital was incorporated into diet for 6 weeks. At the end of 12th week, rats were sacrificed and hepatic glutathions S-transferase placental form positive(GST_{TEX}$P^{+}${/TEX}) foci and serum and liver cholesterol levels were determined. GST_{TEX}$P^{+}${/TEX} formation was significantly decreased by SO feeding when compared with Co feeding but it tended to be enhanced by vitamin E supplementation. Histopathological changes were similar to patterns of GST_{TEX}$P^{+}${/TEX} formation in almost all dietary groups. Serum and hepatic cholesterol levels of SO fed groups were significantly lower than those of CO fed groups. Carcinogen treatments significantly increased serum and liver cholesterol levels in CO fed groups but not in SO fed groups. Correlation data showed a positive correlation(${\gamma}$=0.83, p<0.01) between serum cholesterol level GST_{TEX}$P^{+}${/TEX} foci area. These results indicate that sardine oil as a m-3 fatty acid source may have a reducing effect in rat hepatocarcinogenesis by the altheration of cholesterol metabolism.

• 한국가금학회:학술대회논문집
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• 한국가금학회 2001년도 제18차 정기총회 및 학술발표 PROCEEDINGS
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• pp.58-60
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• 2001

Two experiments were conducted to study the effects of nutrient level and feeding method of split diets for a.m. and p.m. on laying hen performance. In both studies, ISA Brown layers were kept in laying hen cages and treatments were represented by three or four replicates each containing 25 or 34 birds. In Experiment 1, the control group(C) was fed a conventional single diet throughout the day and split diet groups(T1, T2 and T3) were offered high energy/protein - low Ca diet and low energy/protein - high Ca diets in a.m. and p.m., respectively. In split diet groups, ME and CP consumption, and feed cost required per day and per kg egg mass were significantly reduced(P＜0.05) compared to C group, while the hen-day egg production, average egg weight and daily feed intake were not different among treatments. In the second study, C and T1 groups were fed the diets same to the C and T2 groups in Experiment 1, respectively. And T2 group was fed the diet mixed with the split diets for a.m. in mash and p.m. in pellet used in T1 group. In T1 and T2 groups, daily feed intake and average egg weight were significantly reduced(P＜0.05), while the hen-day egg production was not influenced by the feeding system. Daily ME and CP consumption, and feed cost were reduced(P＜0.05) in T1 and T2, while the ME, CP and feed cost required per kg egg mass were not different to the C group. In both study, eggshell qualities were improved(P＜0.05) by split diet feeding. It was concluded the feed and nutrients consumption, feed cost per day or per kg egg mass could be spared by introducing split diets for a.m. and p.m., and the feeding method of mixed diet of split diets was also convenient and effective for sparing feed cost and improvement of eggshell quality.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.283-286
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• 2003

The electric traction load is quite differ from general power system load which is single-phase, high-speed heavy load receiving power from 3-phase power system and also has variable load characteristics over time and space. Therefore, there are inevitably power quality problems such as steady state or transient voltage drop, voltage imbalance and harmonic distortion. In addition, it is expected that transient voltage sag could affect the safety of feeding system. Thus, in this paper transient analysis and voltage sag compensation of AT(Auto Transformer) feeding system are studied. The fault study of traction network is analysed by using PSCAD/SMTDC simulation tool. In addition, application of DVR in electric traction system is proposed to compensate the voltage sag of traction network which is occurred by the fault of utility source. The results of fault study will be a useful research works for operation and setting of electric traction relay. Also, it can be shown that application of the DVR in electric system is very useful to compensate the voltage sag from the result of related simulated work. The results of study will be a useful research works for management and planning of power quality in electric traction system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1281-1283
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors a net size, weight, and parts cost saying result compared to the other systems due to elimination of 60Hz transformer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.467-469
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier, four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.

• 한국군사과학기술학회지
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• 제7권2호
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• pp.126-135
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• 2004

The KSR-III rocket developed by KARI is the first rocket vehicle which is adopting the liquid propellant rocket engine system in Korea and its flight test was successfully done last year, KSR-III is a sounding rocket class launch vehicle, but there is a sense to accomplish design, manufacture, performance test and finally its flight test by domestic technology. In this paper, the authors are intended to introduce the multi-purpose test facility(PTA-II Test Facility) which is constructed for the variety of tests on KSR-III feeding system(single component tests, verification tests, cold flow tests and combustion tests) and its firing test results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1050-1052
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• 2000

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system (3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation. a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.46-49
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kVA) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kVA high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier. four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.