• 전기의세계
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• v.37 no.7
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• pp.64-70
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• 1988

본고에서는 대한전선 기술연구소에서 개발되어 양산되고 있는 비접촉식 외경 측정기인 LASER MICROTEK X8700을 중심으로 비접촉식 외경 측정기의 특징, 측정원리, 구성, 광학계의 이론, 오차요인등에 관해서 논하기로 하겠습니다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.117-117
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• 2004

일반적으로 접촉 피로 마멸은 구름 또는 미끄럼 접촉시 작용하는 반복 응력에 의해 표면과 표면 아래에 균열이 형성되고 성장 및 합체의 과정을 거쳐 표면의 일부가 떨어져 나가는 손상으로 기어나 캠-롤러, 구름 베어링과 같이 구름-미끄럼 접촉상태로 운전하는 기계요소에서 가장 중요하게 고려되어야 할 파손 메커니즘이다. 특히 기어나 구름 베어링 같이 고주기 접촉 피로 특성을 지니는 기계요소의 수명은 피로수명 실험과 통계적 기법을 이용한 Weibull 이론을 기초로 한 수명식을 대부분 사용하고 있다.(중략)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.90-96
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• 1992

경계면 요소를 이용하여 철근콘크리트 구조물의 접촉면 문제를 유한 요소법으로 해석하는 기법에 대하여 연구한다. 본 연구에서는 경계면 요소의 수치해석의 이론과정을 전개하고, 실험 관찰된 부착 시험체에 적용하여 이형철근과 콘크리트 부착기구의 접촉면을 해석한다. 경계면은 특별한 연결요소를 이용하여 재현하며 Mohr-Coulomb의 마찰 이론을 응응한다. 해석의 주요점으로 하중상태에 따라 변화되는 경계면의 접촉상태, 즉 고정(stick), 미끄러짐(slide), 분리(separation)를 묘사하여 경계면 재료의 비선형 거동을 관찰한다. 부착모델의 해석결과는 실험실의 결과와 대체로 일치되며 따라서 철근콘크리트 접촉면의 응력해석을 위해 경계면 요소가 활용될 수 있음을 보여준다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1615-1626
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• 1992

In this study, vibrations and resulting acoustic radiations from an elastic beam impacted by a steel ball were studied theoretically and experimentally. First the transverse vibrations of free-free elastic beams are analysed with modal analysis technique. The impact forces are modeled with the Hertz's theory and the contanct duration is compared with the measured values. Also the calculated beam vibrations are verified with the experimental results. Then the acoustic radiations due to the beam vibration are studied numberically and experimentally. The acousticpressure is calculated assuming the beam has an elliptical cross-section. The predicted acoustic pressure is compared with the measured value. It was found that both the predicted beamvibrations using the Hertz's theory and the estimated acoustic pressure under the assumption of an elliptical cross- section are in very good agreements with the measured values.

• 한국노년학
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• v.38 no.3
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• pp.409-433
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• 2018

The purpose of this study is to examine the effect of contact with the elderly in a daily life on children's ageist attitude. Acknowledging the people's tendency to report in socially appropriate ways to the explicit attitude measurement, implicit measurement is introduced, and relation with the daily contact with elderly(DCE) is analyzed. The research question are as follows: 1) Are these two attitudes explained by different factors? 2) Can DCE alleviate both children's implicit and explicit ageist attitude? 3) How do the contact with grandparent and neighboring elderly affect the children's explicit and implicit ageist attitude? Data was collected from 503 fourth to sixth grade elementary school children. Child-Age Implict Association Test is used to measure implicit ageist attitude. Multinominal logistic analysis and ordered logistic analysis was applied. Followings are the main results: First, explicit and implicit ageist attitudes are found to be related with different predictors. Second, Elderly contact seems to lighten children's ageist attitude overall. Third, the effects of grandparental contact and the neighboring elderly contact on two different ageism were different. While the effect of elderly neighbor contact is limited to the expression of ageism, grandparental contact has a influence not only on the explicit but also on the implicit ageism, even though the effect on implicit attitude is limited in extent. Forth, not the quality of contact but the quantity of it was related to implicit ageist attitude. This result contradicts conventional idea of Intergroup Contact Theory. In the further research, the predictor of implicit ageist attitude need to be throughly examined.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.838-843
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• 2008

Since thickness deformation and lateral deflection often occurs during the collision of flexible bodies, they should be considered simultaneously in the impact analysis. The thickness deformation, however, cannot be considered in beam/shell theory since the thickness is assumed to be constant in the theory. So, solid elements are employed to estimate the thickness deformation. However, the CPU time increases significantly if solid elements are employed. In the present study, a modeling method for the impact analysis of a flexible body employing Hertzian contact theory is presented. The efficiency and the accuracy of the modeling method are discussed with some numerical examples.

• Journal of the Korean Society of Child Welfare
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• no.40
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• pp.9-39
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• 2012

The study aims to examine how exposure to phonography on the internet affects adolescents' behaviour toward sexual assault and the sex trade industry based on the social learning theory. A nationwide survey was conducted on adolescents between the ages of 14 to 19. Responses from a total of 2,829 adolescents were obtained and utilized in the analysis. The analytic findings showed that Korean adolescents are heavily exposed to phonography on the internet. Students use the internet to search for pornographic web sites, and they periodically look for updated materials. The study showed that between 1.8% to 16.5% of adolescents, who were exposed to or watched pornographic materials, committed sexual assault and were guilty of sexually harassing others. 3.5%(95) of those who were surveyed experienced sex trade. Internet chat rooms are considered to be a contributing factor. The results show that adolescents who were exposed to phonography are more prone to committing the acts of sexual assault and sexual harrassment, and tend to be more influenced toward sexual violence.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.174-180
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• 2011

Nondestructive surface imaging of elastic characteristic and mechanical property has been studied on nanoscale surface with ultrasonic AFM. Resonance frequency variation of cantilever is theoretically analyzed with respect to contact mechanics as well as experimentally measured. The contact resonance frequency is calculated theoretically using the spring-mass and Herzian model in accordance with the resonance frequency of UAFM cantilever measured experimentally. Consequently, the topography and amplitude images could be obtained successfully and the elastic characteristic at the nanoscale surface was evaluated qualitatively by amplitude signals.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.132-138
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• 2010

Vibro-contact of cantilever tip is studied with respect to contact mechanics and an elastic characteristic of nanoscale surface is imaged. The contact resonance frequency is calculated theoretically using the spring-mass and Herzian models, and the variation of resonance frequency of cantilever was analyzed when the cantilever was free and contact. The elasticity imaging was also achieved successfully using phase and amplitude signals obtained from the spheroidized steel specimens by prototype ultrasonic AFM.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.1
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• pp.40-46
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• 2011

In the field application of the conventional acoustic nonlinear technique using through transmission of bulk waves to evaluate the contact acoustic nonlinearity(CAN) in solid-solid contact interfaces like as in the closed crack, it has difficulty to access inner position for attaching the pulsing or receiving transducer. In the present study, a new reflection technique has been suggested to measure the acoustic nonlinearity in solid-solid contact interfaces, which uses both of pulsing and receiving transducers on the same side of target and so that it will be very useful for the field application. For this, based on the linear and the nonlinear contact stiffness estimated by the power-model of the contacting pressure, the nonlinear parameter of the reflected ultrasonic wave at the interfaces has been theoretically calculated. Experimental results in contact interfaces of A1606l-T6 alloy specimens with loading pressure showed good agreement with the theoretical predictions, which proves the validity of the suggested reflection mode technique.