• Applied Biological Chemistry
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• v.48 no.1
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• pp.65-69
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• 2005

The physiological activity of St. John's wort extracts were examined. Total phenol contents in the ethanol extracts $(246.0{\pm}10.5\;{\mu}g/ml)$ with St. John's wort leaf was higher than that in water extract $(237.4{\pm}13.2\;{\mu}g/ml)$. The electron donating ability in the water extracts and in the ethanol extracts were 95.0% and 95.2% respectively. Antioxidant protection factor of the ethanol extract was higher than that of the water extract. The water extract from St. John's wort leaves did not show an antimicrobial activity against Helicobacter pylori, but the ethanol extract revealed high antimicrobial activities such as 11 mm of clear zone in $100\;{\mu}g/ml$ of phenol content and 13 mm of clear zone in $150\;{\mu}g/ml$ of phenol content. The hot water extract showed an angiotensin converting enzyme inhibitory activity of 19.2%. The xanthin oxidase inhibitory activity of hot water and ethanol extract were very high, amounting to 84.8% and 100% respectively. The results suggested a possibility for developing the phenol compounds in St. John's wort as anti Helicobacter pylori, anti-oxidant and anti-gout agents.

• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.14-20
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• 2010

This paper was studied on the explosion hazard by spark discharge of the lithium-ion battery. The experimental samples were chosen lithium-ion battery(general, notebook) which were used for source of portable equipment. The IEC(International Electrotechnical Commission) type spark ignition test apparatus and experimental gases such as methane, propane, ethylene or hydrogen were used for explosiveness test. It was confirmed through the experiment that the explosion hazard by spark discharge. Also, it was used thermal imager for confirm that spontaneous ignition possibility by short-circuit. As the result, this paper verified that lithium-ion battery should be used and designed by special attention safety in the hazardous zone which is existed explosiveness gas.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.234-235
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• 2006

The protection relay keeps electric power facilities by using signals of the voltage and current which are input and output terminals of each equipment. Each relay performances protection algorithm by using informations of own protecting zone. To prevent the mal-operation in inrush current, established transformer differential protection method uses the second harmonics as blocking signal. This method is not operate at the initial inrush. However, in case of the parallel operation, if the initial inrush is occurred in one transformer which is generated, the sympathetic inrush Is occurred in adjacent transformer. This paper approach the sympathetic inrush detecting algorithm of a transformer based on agent. Proposed algorithm, when inrush current occurred, distinguish sympathetic inrush or not by using differential current of adjacent transformer. This algorithm have the advantage of the distinguishing initial inrush and sympathetic inrush at operation of parallel transformer

• Journal of Welding and Joining
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• v.19 no.1
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• pp.65-74
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• 2001

A study on the corrosion behavior in case of As-welded and PWHT temperature 55$0^{\circ}C$ of welding part of RE36 steel for marine structure was investigated with parameters such as micro-Vickers hardness, corrosion potential measurement of weld metal(WM), base metal(BM) and heat affected zone(HAZ), both Al anode generating current and Al anode weight loss quantity under sacrificial anode cathodic protection conditions. And also we carried out slow strain rate test(SSRT) in order to research both limiting cathodic polarization potential for hydrogen embrittlement and optimum cathodic protection potential as well as mechanical properties by post-weld heat treatment(PWHT) effect. Hardness of HAZ was the highest among three parts(WM, BM and HAZ) and the highest galvanic corrosion susceptibility was HAZ. And the optimum cathodic polarization potential showing the best mechanical properties by SSRT method was from -770mV to -875mV(SCE). In analysis of SEM fractography, applied cathodic potential from -770mV to -875mV(SCE) it appeared dimple pattern with ductile fracture while it showed transgranular pattern (Q. C : quasicleavage) under -900mV(SCE). However it is suggested that limiting cathodic polarization potential indicating hydrogen embrittlement was under -900mV(SCE).

• Journal of Korea Water Resources Association
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• v.31 no.1
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• pp.27-34
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• 1998

Groundwater simulation model suing GIS and Arc/Info Gridfunctions were used to delineate wellhead protection areas. Groundwater simulation model was developed within Arcview GIS. The model. which integrates the data input and manipulation. Process simulation. and display of the results . was developed by considering time variations of the parameters. The model was applied to the EPA data. The hydraulic distributions from the EPA data and those calculated from groundwater simulation model agree well and zone of influence from EPA data and that calculated suing GRID functions seem to be consistent. The developed model may be an efficient tool to delineate WHPA because it integrates all the processes inside the GIS.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.4
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• pp.221-226
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.221-221
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.78-84
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• 2011

Antagonistic rhizobacteria, more specifically fluorescent pseudomonads and certain species of Bacillus, are known as biocontrol agents of fungal root diseases of agronomic crops. In this study, 144 bacteria were isolated from cucumber rhizosphere and screened as potential biological control agents against Phytophthora drechsleri, the causal agent of cucumber root rot, in vitro condition. Non-volatile compounds of 23 isolates showed noticeable inhibition zone (> 30%) against P. drechsleri, whereas volatile compounds of 7 isolates could prevent more than 30% of the mycelial growth of the fungus. All promising isolates, except of Pseudomonas flourescens V69, promoted significantly plant growth under in vitro condition. P. flourescens CV69 and V11 exhibited the highest colonization on the root. Results of the greenhouse studies showed that a reduction in disease incidence by use of some strains, and particularly use of strains CV6 and V11 as a soil treatment, exhibited a reduction in disease incidence so that suppressed disease by 85.71 and 69.39% respectively. Pseudomonas flourescens CV6 significantly suppressed disease in comparison to Ridomil fungicide. The use of mixture bacterial strains in the soil inoculated by the fungus resulting in falling down the most of the plants which didn't show significant difference with infected control soils without bacteria.

• Journal of Environmental Impact Assessment
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• v.6 no.2
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• pp.61-80
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• 1997

This study tried to propose the guidelines for the ecological preservation zoning in Korea. So some related laws and regulations were inspected, which were Natural Environment Preservation Act, Nature Park Act, Cultural Asset Conservation Act, Forest Act and Urban Planning Act. In these acts, I could find several concepts related to the ecosystem that are described as the protection area. But there aren't detailed and practical characteristics in those concepts. So for making the practical concept of ecosystem preservation, I considered Multiple Use Module, Wildlife habitat model, and Environmental evaluation model. Thorough this step, the process and methodology was established for evaluating and analysing. The potentiality of the GIS system was inspected. So the TM5 scene of the site was acquired and processed by ER-Mapper, Idrisi, Arc/Info and Arcview. And several digitized data were input by scanning and vecterizing. The Erdas format was mostly exchangeable to any program. The site is the Byonsan Peninsula National Park. The forest stand information and topographic data were digitized, types of which are forest year, DBH, density, slope, aspect etc. And also the watershed boundary, roads and paths, natural and cultural resources were mapped and analysed. Modelling of preservation suitability found the dispersed patterns for the best suitable zone through all the site. And the development potential areas were checked on downwatershed. This patterns are thought to result from the forest location for the wildlife habitat and the low altitude and no-steep slopes for developing. And Early warning system concept was introduced by overlapping these two patterns on the both potential area. As the conclusions, I proposed that the preservation zone be assigned according to the watershed unit as the main ecosystem zone. This main area should be linked by the eco-corridor through the point type eco-system. Finally, I thought the comprehensive information system should be established for making the rational and efficient decision making in natural area.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.54-60
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• 2017

A railway rail will be corroded by the repetitive sea wind and fog in the splash and tidal zone such as Youngjong grand bridge. And these rusts of rail could be increased by increasing service period, and it frequently occurred the safety accidents or disorders in electrical problem. In this study, the sacrificial anode cathodic protection method was proposed as a measures for reducing the corrosion of the railway rails in the oceanic climate conditions. As the results of immersion test using the salt water during four months, the sacrificial anode cathodic protection method using the aluminum anode(Al-anode) was evaluated that a distinct effect on corrosion reduction in the rails. Therefore the sacrificial anode cathodic protection method was experimentally proven that a disorders in aspects electric and signal of railway operation condition such as direct fixation track system in Youngjong grand bridge could be prevented by reducing rust falling from the rail. In addition, the installation conditions of the anodes directly affect the transmission range of corrosion potential, the sectional loss of anode, and the corrosion reduction effect. Therefore, to expect the corrosion reduction effect of rails under the oceanic climate conditions for railway track, it was important to adopted the appropriate spacing of anode installation by considering the actual field conditions.