• Journal of the Korean Society of Safety
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• v.22 no.4
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• pp.26-31
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• 2007

According to the statistical analysis on the electrical fire of 2005 years, most of electrical fire is generated from short circuit(4,985 cases), overcurrent(755 cases) leakage current(391 cases), poor contact(378 cases), disconnection(36 cases) on the electrical wiring device. The researches for the fire hazard about normal electric wiring have already been progressing in the advanced country such as USA and Japan, but Comparative study of the disconnection has not been conducted. Therefore, in this paper, we have simulated the thermal analysis for electrical wire according to deteriorating time in a normal state and disconnection with electrical wire using the electrical-thermal finite element method(Flux 3D). This paper acquire basis data of electricity fire signal by disconnection and wish to help for electrical fire cause diagnosis business.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.1
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• pp.83-88
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• 2010

Domestic nuclear steam generators with Alloy 600 HTMA tubes have experienced axial cracking at eggcrate tube support plates(TSPs). The axial stress corrosion cracks were observed at the crevice between outside of tubes and eggcrate TSPs. The root cause of axial cracking was investigated by thermal hydraulic analysis and sludge distribution diagnosis. It is suggested that deposition of sludge at eggcrate TSPs could increase the outside surface temperature of tube and promote the enrichment of impurities at crevice, and thus accelerate cracking. Additionally strategy for reducing the sludge ingress to steam generators is discussed.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.274-275
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• 2011

Fault current problems is considered a serious issue in the power system because large fault currents not only cause many side effects to the equipments of power system but also lead to severe problems, such as blackouts. This paper deals with the structural analysis and 3-phase fault current stability of the future Seoul metropolitan power system. The simulation composition and analysis are performed with the 4th KEPCO power supply planning data using PSS/e. Through the results of the simulations, it can be observed that the future Seoul metropolitan system results in a fault current which exceeds the circuit breaker (CB) rate. This unremovable fault current can cause critical damage to power system. To resolve the problem, the algorithm for the application of Voltage Sourced Converter Back-to-Back High Voltage Direct Current (VSC BTB HVDC) is being proposed. where the most suitable location for solving fault current problem in Seoul metropolitan area is being implemented.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.425-427
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• 2000

The purpose of this study is to find the cause of the damage to the GCB(Gas Circuit Breaker), since the GCB of the 154kV power plant at the Hap-Cheon Dam has already been damaged twice. We researched the characteristics of this class of circuit breaker and the possible causes for this type of damage to the GCB using the FTA(Fault Tree Analysis) Method. We studied the optimal maintenance method of the GCB, the stability analysis and power serge protection of Hap-Cheon Dam, and the power serge and fault list of the power transmission line to help prevent a reoccurrence of the problem.

• Transactions of Materials Processing
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• v.29 no.3
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• pp.151-156
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• 2020

In general, the cause of slab cracking during heat treatment has been analyzed with focus on processing conditions. However, in the present work, the cause of cracking is analyzed based on the microstructural evolution during heat treatment. The microstructural analysis indicates that the structure of the slab consists of three main regions as the top, quarter, and center parts. The tensile properties are investigated in each region of the slab in the temperature range from 25 to 350 ℃. Results demonstrate that the cracking is mainly attributed to the thermal stress and specific morphology of the microstructure. It is proposed that the cracking during the heat treatment is related to the presence of inclusion at the ferrite phase which is located at the boundary of pearlite grains.

• Journal of Agricultural Extension & Community Development
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• v.24 no.1
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• pp.63-81
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• 2017

The purpose of this study is to analyze the changes of time series, the use by farm type and the causes of farm household debt. First, the mid and long term changes in farm household debt over the past 50 years have increased. Since 2010, the share of non-agricultural debt has exceeded the share of agricultural debt. Second, as a result of the analysis of the farm household debt use by farm type - full time&part time, farming type, land size, age, family members - there was a difference between the agricultural and the non-agricultural debt according to the type of farm household in a significant level of 1%. Finally, as a result of the cause analysis of the farm household debt, the related non-agricultural expenditure variables and the dummy variable of the manager's age, family member and land size has a common influence on the farm household debt increase.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.45-46
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• 2006

Usual LEO satellite for earth observation use a blowdown hydrazine monopropellant propulsion system for attitude hold and orbit maintenance. For precision control, thruster valve has very short closing time, but this can cause water hammering and pressure surge. Since water hammering and pressure surge can cause damage of propulsion system and ununiform thrust, Thruster valve closing is one of the special concern during satellite propulsion system design. In this paper, an analysis for propellant feed system is conducted using the method of characteristics. The results represent water hammer effect is negligible even at the worst case and pressure surge can be decreased effectively with a trim orifice.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.942-945
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• 2003

Noise cause is dividing to fluid noise by exhaust flow of fan and vibration noise by rotational vibration of motor. Until now, measuring method has been used to measure vibration by the accelerometer, this method has been not measured for the vibration in some parts of brush and commutator because of motor construction. This research was purposed on the accurate analysis. using laser vibration analyzer, of noise cause against the difficult part in old times. By using this measured data, we would like to use for the design of silent motor.

• Journal of the Korean Society of Safety
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• v.29 no.2
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• pp.7-11
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• 2014

The electric shock victims were predominantly male, and more than half of the victims were found in companies with less than five employees in terms of the scale of company, and also more than half of victims had less than one month of experience for work experience. Considering the category of industry, more than half of the victims were engaged in construction, and considering the subcategory of industries, more than 60% of electric shock victims were found in building and other construction works. This study intended to conduct an in-depth analysis on the cause of electric shock accidents to provide basic data for policy proposing taking into considering the characteristics such as the electric shock path, low voltage, grounding and protection of workers. Also this study conducted an in-depth analysis of electric shock accidents for the past eleven years taking into account the necessity of a long-term plan.

• Journal of Chest Surgery
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• v.26 no.12
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• pp.944-949
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• 1993

Clinical analysis were performed on 247 cases of thoracic trauma, those were admitted & treated at the department of thoracic & cardiovascular surgery,Hanyang University Hospital during the period from Jan,1989 to June,1992. Age distribution of those was from 2 to 80 years old & mean age was 38 years old. The ratio of male to female patient was 186:61 [3:1].This ratio revealed high incidence in male patient. The most common cause of trauma was traffic accident in this series.The modes of injury were as follows: traffic accident 124 cases[50.2%],fall down 52 cases[21.05%], stab wound 47 cases[19.03%] and gun-shut wound 1 case.Ellapse time from accident to admission were 141 cases [57.09%] under 6 hr.Rib fracture were observed in 159 cases[64.37%], hemo or pneumothorax were observed 134 cases[54.25%] of total cases and location distributed Right:Left:Both[74:112:37], in left predominant. Conservative,non-operative treatment were performed in 128 cases and operation[open thoracotomy] 32 cases.Mortality was 1.6%[4 cases] & most common cause of death were due to irreversible shock with brain edema. Conclusively, more evaluation & co-operation of other department were expected treatment & better prognosis.