• Geomechanics and Engineering
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• 제18권5호
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• pp.481-492
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• 2019

Due to the underground openings, the tangentially concentrated stress of the tunnel remains larger at excavation boundary and decreases toward the interior of the surrounding rock with a certain gradient. In order to study the effect of different gradient stress on rockburst, the true-triaxial gradient and hydraulic-pneumatic combined test apparatus were carried out to simulate the rockburst processes. Under the different gradient stress conditions, the rock-like specimen (gypsum) was tested independently through three principal stress directions loading--fast unloading of single surface--top gradient and hydraulic-pneumatic combined loading, which systematically analyzed the macro-mesoscopic damage phenomena, force characteristics and acoustic emission (AE) signals of the specimen during rockburst. The experimental results indicated that the rockburst test under the gradient and hydraulic-pneumatic combined loading conditions could perfectly reflect the rockburst processes and their stress characteristics; Relatively high stress loading could cause specimen failure, but could not determine its mode. The rockburst under the action of gradient stress suggested that the failure mode of specimen mainly depended on the stress gradient. When the stress gradient was lower, progressive and static spalling failure occured and the rockburst grades were relatively slight. On the other hand, shear fractures occurred in rockbursts accounted for increasingly large proportion as the stress gradient increased and the rockburst occurred more intensely and suddenly, the progressive failure process became unconspicuous, and the rockburst grades were moderate or even stronger.

• 한국심리학회지 : 문화 및 사회문제
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• 제15권4호
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• pp.529-546
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• 2009

한국적 상담의 한 모형으로 제안된 현실역동 상담접근의 특성 및 다양한 상담이론이 근거하고 있는 주요 범주를 소개한다. 그리고는 갈등문제를 일으킨 실체에 대한 정확한 이해 즉, 현실역동 상담에서 제 1의 특성으로 삼고 있는 문제의 진상에 대한 파악이 얼마나 중요한 것인지를 질적 연구의 한 방안인 "이야기 방식'으로서 부각시키고자 한다. '이야기 방식'은 상담자의 진술적 보고로서 상담분야에서 널리 사용되고 있는 축어록 방식과 성격을 달리한다. 이야기 방식은 해석학적 모델에 근거한 하나의 방안으로서 의도한 정보 및 의미 전달에 매우 유용하다. 본 연구에 소개된 사례의 내담자는 가족 간의 불화로 2년 이상 개인상담을 받는 동안 진전을 보이지 않다가 집단상담에 와서 문제의 실체를 명확하게 파악하고 곧 바로 호전을 보인 사람이다.

• 전기학회논문지
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• 제57권10호
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• pp.1752-1758
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• 2008

This paper deals with the reduction of friction torque in permanent magnet motors by using the heat treatment of stator core. The stator core is made of electrical steel sheared by the punching die. From the punching process, large mechanical stress acting on the edge of stator tooth induces significant plastic and elastic deformation and then cause the change of magnetization properties. Then, the mechanical and magnetic unbalance in the sheared region of stator tooth produced by material cutting has influence on the friction torque. This paper investigated the effect of the punching process on the magnetization process and the mechanical deformation, and then proposed the stress relief annealing method for the reduction of friction torque among one of motor characteristics.

• 한국콘텐츠학회논문지
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• 제17권9호
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• pp.466-475
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• 2017

스트레스는 매일 살아가면서 사소한 일부터 큰 충격을 받는 삶의 주요한 사건까지 다양한 요인으로부터 온다. 이는 어느 한 시기에만 나타나는 것이 아니라, 생애에 거쳐 나타나므로 지속적으로 스트레스를 관리할 수 있는 연구가 필요하다. 본 연구에서는 사용자 스스로 스트레스를 진단, 관리할 수 있는 홍채 분석기반 시스템을 개발하였다. 그리고 홍채진단에 의한 스트레스 지수와 설문기반의 스트레스 지수의 상관성을 분석한 후, 사용자의 스트레스 지수를 정량화하였다. 본 연구에서 제안하는 시스템은 사용자가 쉽게 현재 자신이 느끼고 있는 스트레스 정도를 알 수 있고, 이에 상응하여 예측되는 질병에 대한 조기 진단 및 질병예방의 하나의 방법으로 사용할 수 있을 것이다.

• 한국압력기기공학회 논문집
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• 제6권1호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.207-210
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• 2001

Electrical equipment for railway is always experiencing wear and degradation by mechanical, electrical and environmental stress in service and the fault or the accident of high voltage main circuit directly causes operation interruption. Particularly propulsion drive of high speed switching inverter takes the form of specific degradation mechanism such as fast rising transient surge, reflective overvoltage and harmonic stress, and it is known that it threatens the long life and the reliability of electrical equipment. In this paper, statistics of fault and accident on main electrical equipment for railway are presented and also insulation degradation mechanism, which governs end life of electrical device, is analyzed. Finally the method of fault respondence and reliability improvement on the main electrical equipments will be reviewed in order to prevent operation interruption.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.50-55
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• 2008

In order to investigate and estimate the cause of fatigue crack occurred to curved girder bridge that is used during 20 years, in this study, filed tests to obtain the characteristic of stress hysteresis were performed under the real traffic flows. From these test results, we analyzed the cause of fatigue crack for various fatigue crack patterns. Also, the characteristic of structural behavior for the curved girder bridge were examined from the FE analysis. In addition, to retrofit various fatigue cracks occurred in the bridge, FE analyses considering the characteristics of crack patterns were performed and retrofitting methods were suggested.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2010년도 춘계학술대회
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• pp.117-125
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• 2010

Cerebrovascular and cardiovascular diseases (CVDs) are a major cause of deaths among workers as well as in general population in Korea. Occupational stress like long working hours or overwork can cause sudden unexpected death in a worker who had been suffering from an aggravated preexisting condition such as hypertensive or arteriosclerotic diseases, The Korean government has compensated the cases of cerebrovascular disease and cardiovascular disease due to overwork, but neither a resonable definition of overwork nor detailed evaluation guideline has been officially provided to verify overwork, so that the prevention of, as well as compensation for workers' occupational stress-related cardiovascular attacks, cannot be carried out efficiently. A thorough understanding of the etiopathology of WR-CVDs can be very helpful in developing a prevention strategy.

• 식품보건융합연구
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• 제7권5호
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• pp.19-31
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• 2021

The purpose of this study is to examine whether there is a mediating effect of hopelessness the relationship between perceived stress and suicidal ideation in college students. For this study, a survey was conducted on perceived stress, suicidal ideation, and mental health, self-esteem, problem drinking, and stress among 103 college studentsin Gyeonggi do. The results of this study are as follows. It was found that COVID-19 correlated with perceived stress, hopelessness, and suicidal ideation of college students. The hopelessness completely mediated between perceived stress and suicidal thoughts of college students, which is consistent with previous studies. This study is meaningful in that it confirmed relationship between the perceived stress, hopelessness, and suicidal ideations in college students due to COVID-19, reflecting the new situation of the times. Coronavirus will worsen people's mental health disorders and cause new stress-related disorders. Therefore, mental health researchers, clinicians, and people working in trauma-related fields should find ways to reduce the incidence of coronavirus-related trauma stress and prevent its effects. It is necessary to expand the psychological vaccine program to improve the resilience of the public. Since there are individual differences in resilience, it is necessary to strengthen the psychological vaccine program for each subject considering resilience.

• Nuclear Engineering and Technology
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• 제47권1호
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• pp.115-125
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• 2015

Background: Residual stress always exists on any kind of welded area. This residual stress can cause the welded material to crack or fracture. For many years, the hole-drilling method has been widely used for measuring residual stress. However, this method is destructive. Nowadays, electronic speckle pattern interferometry (ESPI) can be used to measure residual stress with or without the hole-drilling method. ESPI is an optical nondestructive testing methods that use the speckle effect. Mechanical properties can be measured by calculation of the phase difference by the variation of temperature, pressure, or loading force. Methods: In this paper, the residual stress on the butt-welded area is measured by using ESPI with a suggested numerical calculation. Two types of specimens are prepared. Type I is made of pure base metal part and type II has a welded part at the center. These specimens are tensile tested with a material test system. At the same time, the ESPI system was applied to this test. Results: From the results of ESPI, the elastic modulus and the residual stress around the welded area can be calculated and estimated. Conclusion: With this result, it is confirmed that the residual stress on the welded area can be measured with high precision by ESPI.