• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1265-1270
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• 2018

One of the ways to improve the stability of power facilities used in power systems is to use power surge arresters and to protect against transient overvoltages and surges in normal operation. Also it is important to reduce the impact of lightning strikes because lightning can create overvoltage in the grid of the wind turbine and affect power quality. So This paper analyzes the effects of overvoltage and adjacent turbines due to single strike and multi strike to ground impedance changes when the surge arrester is deteriorated in a wind power farm.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.4
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• pp.207-212
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• 2015

The use of groundwater and ground_heat is one of the ways to use natural and renewable energy, and it has been considered as a technology to reduce greenhouse gas emissions and increase energy-saving. There are a few researches on the optimum design for the open-loop geothermal system. In this study, to develop the optimal design method numerical simulation of the open-loop geothermal system with two-wells was performed by a groundwater and heat transfer model. In this paper, a study was performed to analyze the system performance according to well distance and pumping flow rate. In the result, average heat exchange rate and heat source temperature were calculated and it was found that they were dependent on the pumping rate.

• Korean Journal of Construction Engineering and Management
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• v.11 no.2
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• pp.147-155
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• 2010

Traditional procurement methods have revealed many disadvantages especially the adversarial relationship between parties. After several decades of application, partnering has shown that it is an innovative arrangement that help to reduce many problems having existed in traditional arrangement. It can provide a win-win working attitude in a construction project. Partnering in construction has been applied in several ways in recent years in Vietnam. This mechanism can help both local and foreign construction participants to mutually offset their differences when implementing projects. This paper has investigated and introduced the incentives of partnering from Vietnam perspective in terms of foreign and local participants perceptions. It has been shown that 'to learn mutually among participants' and 'to increase bidding advantages' are the most important incentives according to foreign and local practitioners respectively.

• Korean Journal of Biological Psychiatry
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• v.23 no.4
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• pp.123-129
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• 2016

Depression has a relatively high lifetime prevalence rate in spite of a genetic influence on its etiology and a high mortality rate in untreated cases. This suggests the possibility that depression gives us evolutionary benefits which we do not exactly know yet. There have been several hypotheses which tell us what evolutionary advantages depression could give us. The psychic pain hypothesis considers sad or depressed mood as a negative reward just like physical pain which we have to avoid for our protection and survival. The social rank hypothesis holds that depressed mood is very similar to the emotional state of the defeated in social competition which prevents him from further protesting or fighting that might cause additional damage to him. The inclusive fitness hypothesis views suicide as a sacrifice phenomenon to contribute to inclusive fitness. These hypotheses gives us new insights into mood disorders and also some suggestions about the conditions in which depressed mood or suicidal behaviors increase and the ways to reduce them.

• Journal of Korean Physical Therapy Science
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• v.9 no.1
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• pp.159-166
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• 2002

The purpose of this study was to review the knowledge related to historic background, causes, symptoms, etiology and rehabilitation methods related to this disease and suggest some ways to reduce complications from it. The importance of underwater pressure disease was not emphasized, therefore, there is a need for continuous research on treatment methods and prevention for it. As one goes into the deeper water, they will be affected by the hydraulic pressure rather then the atmospheric pressure, and it will be increased 1mmHg by 10meters. Underwater pressure disease can be occurred when one comes out of deeper water too quicked. This results the imbalance of the composition rate of nitrogen in blood. However, there is not enough facilities to treat this disease and these facilities are located in limited areas. Therefore, there is an urgent need to set up a medial center that is specialized in prevention and treatment of underwater pressure disease.

• Journal of Korean Society for Quality Management
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• v.24 no.2
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• pp.158-171
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• 1996

Outlier is one that appears to deviate extremely from other data in collected data. Thus treatment of outlier is very important work, because it is to distort the meaning of whole data in its analysis and to reduce the accuracy and validity for adequate models. The aim of this paper is to present some ways of handling outliers in given data and to investigate the effect of the analysis result before and after outlier reject. As a variety of methods has been proposed, we sellect the linear regression analysis and two linear programming techniques and compare to each result.

• Journal of Hydrogen and New Energy
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• v.32 no.4
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• pp.263-270
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• 2021

In this study, we proposed the necessity of reusing the battery industry after domestic use, preparing legal arrangements by step for recycling, clarifying responsible materials by processing stage, and establishing infrastructure and screening diagnostic rating system. The purpose of this study is to establish a life cycle integrated management system for electric vehicle batteries and to find suitable ways for improving the lifespan of electric vehicle batteries, reuse, and recycling in stages to avoid other environmental pollution problems due to batteries after using electric vehicles used to reduce environmental pollution due to climate change.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.116-124
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• 2011

A service robot can identify its own position relative to landmarks, the locations of which are known in advance. The main contribution of this research is that it gives various ways of making the self-localizing error smaller by referring to special landmarks which are developed as high gain reflection material and coded array associations. In this paper, the authors propose a set of indices to evaluate the accuracy of self-localizing methods using the selective reflection landmark and infrared projector, and the indices are derived from the sensitivity enhancement using 3D distortion calibration of camera. And then, the accurarcy of self-localizing a mobile robot with landmarks based on the indices is evaluated, and a rational way to minimize to reduce the computational cost of selecting the best self-localizing method. The simulation results show a high accuracy and a good performance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.3
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• pp.74-81
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• 2009

At present, industries and researchers are looking for ways to reduce the use of lubricants because of ecological and economical reasons. Therefore, metal cutting is to move toward dry cutting or semi-dry cutting. One of the technologies is known as MQL machining. This paper presents an investigation into MQL machining with the objective of evaluating cylindricity and cooling effect for the turning process of SM45C. To reach this goal, cylindrical-outer-diameter turning experiments are carried out according to cutting conditions with fluid, MQL and dry machining methods. A cutting force, tool-shank temperature and cylindricity of workpiece are measured and analyzed. The correlation between cutting conditions and cylindricity are evaluated according to cooling lubricant environments.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.151-157
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• 2013

This paper is a comparative study on risk assessment policy between Asian countries such as Japan, Korea, Singapore and EU countries, German, UK. Risk assessment is a tool adopted currently in many countries in order to reduce occupational risk in workplace because it help employers to identify their hazard arousing in their working conditions then to settle the issues. This paper compares institutional framework posed in EU and Asian countries. As a result of comparative study, EU countries have more concrete legal system for risk assessment than Asian countries. But Asian countries are now interested in risk assessment such as Japan, Korea and Singapore. The author also suggests successful ways to settle down the risk assessment policy in a country. These findings help to understand occupational health and safety policy on risk assessment in Asian countries.