• 대한인간공학회지
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• 제14권1호
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• pp.37-57
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• 1995

The purpose of this study was to investigate the elastic effect of deformation and restriction in wearing a support type panty stocking (PS). The study investigated deformation rate in all surface area, deformation rate in local area, length deformation rate, changes in slip and feeling of restriction under the standard laboratory condition. Two healthy adult females in twenties wore four types of PS. The result were as follows : The deformation rate in all surface area was 117 .approx. 132% in wearing support type PS, 157% in wearing mono type PS, due to the intensities of restriction. The deformation rate in local area was in order, course > oblique > wale direction. The largest deformation rate was observed in hip girth. Between the deformation rates in all surface and local areas was a high correlation acknowledged, especially the course direction showed a high correlation. Support type PSs showed more deformation and changes of slip than wool and mono type PS. Especially, changes of slip at the knee appeared greatly. The responses of restriction evaluated from a paired comparison method were in order, JS 2 > KS 4 > KS 9 > KS 5 > KS 1 > KM 3.

• 한국표면공학회지
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• 제8권2호
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• pp.20-27
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• 1975

• 한국분무공학회지
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• 제10권4호
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• pp.26-31
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• 2005

Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and air. We proved the interaction between vortex pairs and free surface on each condition that is created by the end of delta wings. Another purpose of this study is to investigate the effect of surface active material which call change the surface tension and we must consider when we refer to turbulent flow on surface tension. Therefore, this research examined the growth process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely but the vortex pairs in contaminated free surface and rigid, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid, no slip is stronger than before. and we can find the vortex shape which roll up more completely. However, these will disappear by the effect of wall.

• 대한기계학회논문집A
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• 제21권3호
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• pp.511-518
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• 1997

The technique of fretting fatigue test was developed and fretting fatigue tests of A12024-T4 were conducted under several conditions. The newly developed calibration methods for measuring surface contact tractions showed good linearity and repeatability. The plate type specimen to which tow bridge type pads were attached and vision system was used to observe the crack behaviour. The oblieque cracks appeared in the early stage of crack growth and they became mode I cracks as they grow about 1 mm. The mode I transition points were found to be longer when surface tractions are higher or bulk stress is lower. Before the crack becomes mode I crack, 'well point' where crack grow about rate is minimum, was detected under every experimental condition. The crack behaviour was found to be affected by surface tractions, contact area, bulk stress. It was also found that partial slip and stick condition is most detrimental and the crack starts from the boundary of stick and slip. For gross slip crack started at the outside edge of pad. After crack mode transition, fretting fatigue cracks showed almost same behaviour of plain mode I fatigue cracks. Equivalent stress intensity factor was used to analyze the behaviour of fretting fatigue cracks and it was found that stress intensity factors can be applied to fretting fatigue cracks.

• 대한기계학회논문집A
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• 제26권12호
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• pp.2581-2589
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• 2002

In this research, fretting tests were conducted in air to investigate the wear characteristics of fuel cladding materials with the fretting parameters such as normal load, slip amplitude, frequency and the number of cycles. A high frequency fretting wear tester was designed for this experiment by KAERI. After the experiments, the wear volume and the shape of wear contour were measured by the surface roughness tester. Tribologically transformed structures(TTS) were analysed by means of optical and scanning electron microscopes to identify the main wear mechanisms. The results of this study showed that the wear volume were increased with increasing slip amplitude, and the shape of wear contour was transformed V-type to W-type. Also, it was found that the critical slip amplitude was 168${\mu}{\textrm}{m}$. These phenomena mean that wear mechanism transformed partial slip to gross slip to accelerate wear volume. The wear depth increased with an increase of friction coefficient due to increase of normal load and frequency. The fretting wear mechanisms were believed that, after adhesion and surface plastic deformation occurred by relative sliding motion on the contact between two specimens, TTS creation was induced by surface strain hardening and wear debris were detached from the contact surface which were produced by the micro crack propagation and creation.

• 한국지반공학회논문집
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• 제15권3호
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• pp.27-40
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• 1999

사면안정해석을 수행하기 위하여 많이 사용하는 한계평형방법은 일정한 가정을 하여 안전율을 평형에 필요한 응력과 흙의 전단강도의 비로 정의하여 대상사면의 안전율을 구한다. 유한요소법을 이용한 사면안정해석방법은 응력상태를 유한요소법으로 구한 후 원호나 대수나선형등의 일정한 모양의 사면 파괴선을 가정하여 반복적으로 최소안전율을 구한다. 본 연구에서는 유한요소법을 이용한 사면안정해석방법을 개발하여 사면의 가장 취약한 부분을 따라 파괴선이 발생하도록 하였다. 이것은 요소내의 국부안전율과 파괴각을 고려하여 사면파괴선을 자동적으로 구할 수 있도록 함으로써 가능한데 이 방법은 임의의 파괴선을 가정할 필요가 없으며 절편에 작용하는 힘에 대하여 가정을 할 필요가 없고 임의의 모양의 파괴선을 구할 수 있는 장점이 있다. 본 연구에서는 개발된 해석방법을 검증하기 위하여 가상의 사면, 자연사면, 그리고 댐사면에 적용하여 실무에서 많이 사용하는 한계평형방법 프로그램인 STABL5M과 SLOPE/W과 비교 평가하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제27권1호
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• pp.54-63
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• 2023

본 논문에서는 부식된 철근과 콘크리트 계면의 부착강도-슬립거동에 있어 부식수준 및 균열폭의 영향에 대한 연구를 수행하였다. 기존의 연구는 주로 부식수준에 따른 부착강도 저하에 초점을 맞추고 있으나 부식에 의한 콘크리트 표면 균열폭에 따른 부착강도 저하에 관한 연구는 매우 적다. 따라서 본 연구에서는 부식된 철근과 콘크리트 접합부의 부착강도, 슬립 거동 및 철근의 질량손실 등을 평가하고 균열폭 대비 접합성능을 확인하기 인발시험을 실시하였다. 그 결과로 표면 균열폭에 따른 접착강도 저하의 경향성이 부식수준에 따른 경향성보다 균등하게 나타났다. 따라서 부식수준에 비해 콘크리트 표면 균열 발생 여부가 부착강도-슬립거동 관계의 성능저하를 판단하기에 적합한 것으로 판단된다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.263-268
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• 2000

The fretting damage of the contact between Zircaloy-4 and Inconel 600 have Investigated. A fretting wear tester was designed to be suitable for this fretting test. In this study, the number of cycles, slip amplitude and normal load were selected as main factors of fretting wear. As the result of this research the wear volume increased with the increase of loads, slip amplitudes and the number of cycles and was more affected by slip amplitudes rather than by load. According to SEM, stick, partial slip, gross slip were observed on the surface of both specimens and wavy worn surfaces as the typical fretting damage were also Investigated due to accumulation of plastic flow.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.67-72
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• 2004

Fundamentally, slip displacement should be known to solve the problem related to the fretting wear. For this, methods for measuring the slip displacement range in the contact surface of the tube and the supports were introduced and analyzed in this study. Also the increment of the slip displacement during a cycle was calculated using the revised formulas. As a result, the slip displacement newly evaluated was much higher ($7{\sim}50$ times) than that previously evaluated especially in the case of the gap existence. This enables to explain the severe wear found when there was a gap between the tube and the supports.

• 한국세라믹학회지
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• 제35권2호
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• pp.180-184
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• 1998

It was examined that the rheological behaviors of fly ash 70wt%-clay 30wt% slip in which nonplastic fly ash was a major component. We have systematically investigated the effects of deflocculant(Tetrasodium pyrophosphate ; Na4P2O7 nH2O Sodium silicate; Na2SiO3) and coagulant(CaSO4) on the rheological behavior of ash-clay slip. Ash-clay slip have been characterized on the basis of the time dependent rheology which was done out by the gel-curve test. Dispersion mechanism of ash-clay slip is the steric stabilization by the Na2SiO3 coating of cenospheres surface. Coagulated slip seems to have the new network structure and shows the gellation behaviors which makes it possible to direct coagulated casting(DCC).