• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.389-395
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• 2001

To restrain contact failure, present study investigates the influence of edge machining of an indenter (punch). As for the edge machining, rounding, chamfering, and chamfering and rounding are considered. Contact mechanics is consulted to examine the traction profile and the size of the contact region which are directly influenced by the end profile of the indenter. The effect of rounding size (i.e., radius) in the case of the chamfering and rounding edge-indenter is studied. Shear traction is also evaluated within the regime of partial slip. Size of slip region and its expansion rate due to the increase of shear force are considered to investigate the shape effect of the indenter on contact failure.

• Tribology and Lubricants
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• 제21권6호
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• pp.289-295
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• 2005

Most machine element, such as gears and bearings, are operated in the mixed lubrication region. Contact between two asperities has an effect on machine life by increasing local pressure. To estimate fatigue life exactly, asperity contact should be considered as a factor of fatigue life because this happening produce friction, abrasion and make flash temperature. In this paper, asperity contact is considered as a result of film breakdown when lubricant pressure is not enough to separate two asperities. Contact pressure is calculated to asperity overlap region and added to lubricant pressure. For this model, numerical procedure is introduced and the result on surface roughness and velocity for wheel bearing is presented. Results of EHL analysis for wheel bearing show that asperity contact is occurred at the edge ofEHL conjunction where has a insufficient lubricant pressure to separate two surface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.616-621
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• 2005

Most machine element, such as gears and bearings, are operated in the mixed lubrication region. Contact between two asperities has an effect on machine life by increasing local pressure. To estimate fatigue lift exactly, asperity contact should be considered as a factor of fatigue liff because this happening produce friction, abrasion and make flash temperature. In this paper, asperity contact is considered as a result of film breakdown when lubricant pressure is not enough to separate two asperities. Contact pressure is calculated to asperity overlap region and added to lubricant pressure. For this model, numerical procedure is introduced and the result on surface roughness and velocity for wheel bearing is presented. Results of EHL analysis for wheel bearing show that asperity contact is occurred at the edge of EHL conjunction where has a insufficient lubricant pressure to separate two surface.

• Tribology and Lubricants
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• 제18권3호
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• pp.228-234
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• 2002

Generally, space structures are subjected to severe situations, such as, sublimation, strong evaporation of lubricants, thermal stresses, high temperature gradients, irradiation, impacts by microscopic meteorites, and other factors. Recent]y, various kinds of coatings are applied to the parts under heavy contact stresses, in order to insure long wear-free lives and/or reduce friction coefficients. In space structures, molybdenum disulfide is using frequently. Moreover TiN, Al$_2$O$_3$, PTFE(Poly Tetra Fluor Ethylene) are introduced recently for space structure. In this part we are going to apply the partial model method, developed in reference[11] to analyze part with coated layer. In referencer[l1], we compute the reasonable size of partial model and aspect ratio. Using these data, we analyze the structures coated with TiN, Al$_2$O$_3$, PTFE under contact load, temperature and crack model . Beside, we consider the stress analysis under time dependent load and transient thermal effect.

• 대한치과보철학회지
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• 제26권1호
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• pp.197-206
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• 1988

The purpose of this study was to investigate the effect of wearing the removable partial denture on plaque accumulation. Twelve removable partial denture cases were examined. Patients were recalled three consecutive 3 day periods. Plaque index was measured after each 3 day period. (1) not wearing the denture, (2) wearing the denture, (3) wearing the denture after intensive tooth brushing instruction. The results were as follows: 1. Plaque indices of all the remaining teeth were higher following the wearing of removable partial denture than those of teeth not wearing the denture and those of teeth after intensive tooth brushing instruction. 2. Plaque indices showed statistical difference between all the tooth surfaces which were in contact with the denture and those which were not. 3. Plaque indices showed no statistical difference between buccal and lingual surfaces which were in contact with the denture and those which were not. 4. Plaque indices showed statistical difference between proximal surfaces which were in contact with the denture and those which were not.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.37-43
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• 2000

The effect of the alignment of the contacting bodies is concerned. Tilting of a body (indenter) is regarded as a mis-alignment. Recently developed method fur evaluating the contact normal traction is introduced and discussed, in which piecewise parabolic profile is considered as a generalized contact profile. Indentation by a wedge with rounded apex is solved as an example problem. In the case of partial slip regime, the variation of shear traction is examined during the closed path of shear force by using the efficient numerical technique. Concentration of the slip region is also investigated. By evaluating the energy dissipation from the contact surface, the effect of the mis-alignment-alignment on wear is discussed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.643-648
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• 2011

Fatigue crack in most rails take place by rolling contact between wheel and rail in railway industry. Therefore, it is critical to understand the rolling contact phenomena, especially for the three-dimensional situation. In this paper the steady-state rolling contact problem of KTX wheel and rail (UIC60) has been studied with three-dimensional finite element analysis. The variation of contact pressure and contact stresses on rolling contact surface were obtained using the finite element method. The three-dimensional distribution of contact stresses on the contact surface are investigated. Results show that the distribution of shear stress and contact stress (von Mises) on the contact surface varies rapidly as a result of the variation of stick-slip region. The contact stress at the leading edge is greater than at the trailing edge because of stick and slip phenomena.

• 대한치과보철학회지
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• 제21권1호
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• pp.67-72
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• 1983

Path of insertion(1) can be defined that the direction of movement of an appliance from the point of initial contact of its rigid parts with the supporting teeth to the place of final rest. Krol(2) described that in the conventional path of insertion, all the rests are seated more or less simultaneously but in the use of the rotational path one segment of the partial denture is seated first then the remainder of the prosthesis is rotated into position. The rotational path of insertion is limited primarily to the tooth borne prosthesis. Its great advantages are the elimination of anterior clasps to improve ethetic and reduction of tooth coverage to minimize plaque accumulation. Either a rigid minor connector or proximal plate provides retention through its intimate contact with a proximal tooth surface below the height of contour as indicated at a o-degree tilt. A specially designed rest in conjunction with this retentive component satisfies the basic requirements of clasp design. The purpose of this study was a clinical evaluation of rotational path removable partial dentures. Author delivered rotational path removable partial dentures to three different cases of patients and evaluated function of the dentures, difficulties of removal and insertion of the dentures and supporting structures of the abutment teeth by means of clinical and X-ray examinations for eighteen months. According to the examination data author came to the conclusion that the prognosis of the rotational path removable partial dentures was excellent.

• 전기전자학회논문지
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• 제28권2호
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• pp.131-135
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• 2024

본 연구에서는 전력설비의 전력선에 탈부착이 용이하도록 전류계(CT) 방식의 비접촉식 부분방전 측정용 센서를 자체 개발하고, 그 특성평가 결과에 대하여 논하였다. 자체 제작한 HFCT센서의 주파수 응답특성이 20[kHz]에서 20[MHz]까지 측정 가능함을 보였으며, 정극성 방향으로 배치한 경우의 평균감도가 0.308[mV/pC], 부극성 방향으로 배치한 경우는 0.459[mV/pC]로서 부극성으로 배치한 경우가 정극성으로 배치한 경우보다 감도특성이 우수함을 보였다. 실제 부분방전 발생 및 특성측정 실험을 통하여 침전극 끝단에서 매우 미소한 코로나 기중방전이 시작되는 펄스 신호를 측정하는 것이 가능하므로 전력설비에서 발생될 수 있는 다양한 형태의 부분방전을 충분히 측정가능할 것으로 판단된다.

• International Journal of Advanced Culture Technology
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• 제10권3호
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• pp.263-271
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• 2022

The purpose of this study is to identify the degree of participation and the impact of social media sports contact motivation on sports activities. In order to clarify the purpose of this study, a total of 300 students from 150 male and 150 female university students in Gwangju and Jeonnam provinces in 2020 were selected by the convenience sampling method. The survey tool used to achieve the purpose of this study is the questionnaire method. Therefore, the questionnaire, which has already been verified for reliability and validity in domestic and foreign previous studies, was re-quoted, modified, or supplemented for the purpose of this study. For data processing, SPSS Windows 20.0 Version was used. For specific statistical analysis, frequency analysis, exploratory factor analysis, reliability analysis, and multiple regression analysis were performed according to the purpose of analysis. The results obtained through these results are as follows. First, it was found that the contact motivation for social media sports partially affected the degree of participation in social media sports. Second, it was found that social media sports contact motivation has a partial influence on sports participation. Third, the degree of social media sports participation was found to have a partial influence on sports participation.