• 한국기계가공학회지
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• 제3권2호
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• pp.86-94
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• 2004

The flash temperature distribution on the contact surfaces between cam and roller-follower mechanism was analysed numerically. The elasto-hydrodynamic lubrication pressure and film thickness were used to get the accurate analysis results. The temperature distribution was obtained by numerical integration by making use of Carslaw and Jaeger's formulation to the whole contact surfaces. The maximum flash temperature was increased with both the increasing slip ratio of the contact surface and increasing external load Profile of the temperature distribution was affected by the sliding velocity of the surface.

• 한국정밀공학회지
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• 제33권2호
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• pp.139-147
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• 2016

Performances of urethane packing in the hydraulic breaker were analyzed using a finite element method. Because of high temperature and high pressure in the hydraulic breaker, it is better to use urethane rather than rubber as a packing material. We obtained the physical properties of urethane at elevated temperature by the tensile test. We analyzed buffer seal and U-packing maintaining the pressure and preventing oil leakage. Deformation, stress distribution, contact length, contact pressure of packing at each pressure step were obtained using finite element analysis. As the temperature increases, stress and contact force tend to decrease at low pressure. As the gap between piston and cylinder increases, contact length and contact forces decrease. Consequently, it is possible to design the packing section using these analyses, and construct a system to predict the possibility of oil leakage in the hydraulic breaker.

• 대한기계학회논문집A
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• 제35권10호
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• pp.1237-1242
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• 2011

족저부의 압력 분포를 해석하기 위하여 인체에 근접한 족부 상세 해석용 모델을 개발하였다. 이 상세 해석용 모델은 족부의 단층촬영 영상(CT scan image)으로부터 밀도 차이에 따라서 골격부와 피부 및 피하조직을 각각 3D CAD 모델로 변환한 후에 결합하여 구성하였며, 근육과 뼈, 피부 모두를 반영한 3D 족부 유한요소해석 모델로 개발하였다. 개발된 3D 족부 유한요소모델에 대하여 NASTRAN의 접촉해석을 수행하여 족저압의 분포를 계산하였으며, 이러한 결과는 균일분포압력을 작용시키는 당뇨병 환자용 신발 설계의 기초 자료로 활용될 수 있다.

• 한국전문물리치료학회지
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• 제20권4호
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• pp.55-64
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• 2013

The first purpose was to identify the plantar pressure distributions (peak pressure, pressure integral time, and contact area) during level walking, and stair ascent and descent in asymptomatic flexible flatfoot (AFF). The second purpose was to investigate whether peak pressure data during level walking could be used to predict peak pressure during stair walking by identifying correlations between the peak pressures of level walking and stair walking. Twenty young adult subjects (8 males and 12 females, age $21.0{\pm}1.7$ years) with AFF were recruited. A distance greater than 10 mm in a navicular drop test was defined as flexible flatfoot. Each subject performed at least 10 steps during level walking, and stair ascent and descent. The plantar pressure distribution was measured in nine foot regions using a pressure measurement system. A two-way repeated analysis of variance was conducted to examine the differences in the three dependent variables with two within-subject factors (activity type and foot region). Linear regression analysis was conducted to predict peak pressure during stair walking using the peak pressure in the metatarsal regions during level walking. Significant interaction effects were observed between activity type and foot region for peak pressure (F=9.508, p<.001), pressure time integral (F=5.912, p=.003), and contact area (F=15.510, p<.001). The regression equations predicting peak pressure during stair walking accounted for variance in the range of 25.7% and 65.8%. The findings indicate that plantar pressures in AFF were influenced by both activity type and foot region. Furthermore the findings suggest that peak pressure data during level walking could be used to predict the peak pressure data during stair walking. These data collected for AFF can be useful for evaluating gait patterns and for predicting pressure data of flexible flatfoot subjects who have difficulty performing activities such as stair walking. Further studies should investigate plantar pressure distribution during various functional activities in symptomatic flexible flatfoot, and consider other predictors for regression analysis.

• 수산해양교육연구
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• 제22권4호
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• pp.508-515
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• 2010

This study was conducted on male college students with supinated foot to measure the foot pressure by having them wear three kinds of wedge insoles ($0^{\circ}$, $3.5^{\circ}$, $7^{\circ}$). Foot contact time, foot contact area, peak pressure and mean pressure were measured using a foot pressure distribution measuring instrument. And the surface of the foot sole was divided into 10 areas. Regarding foot contact time, there was no statistically significant difference by showing $0.69{\pm}0.004$ seconds at $3.5^{\circ}$ and $0.68{\pm}0.006$ seconds at $0^{\circ}$ and $7^{\circ}$. Regarding the foot contact area, it appeared broad in the inside area of the foot according to wedge insole, and there was statistically significant difference in the area 1 of the rear foot(p< .01) and the area 3 of the middle foot(p< .05). The peak pressure by foot area decreased in the outside of the foot according to wedge insole, while increasing in the inside of the foot. Among the areas, there was statistically significant in the area 2 of the rear foot (p< .01) and the area 3 of the middle foot (p< .05). Regarding the mean pressure by foot area, the pressure roughly increased in the inside area of the foot according to wedge insole, while decreasing in the outside of the foot.

• 한국기계가공학회지
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• 제3권3호
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• pp.64-70
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• 2004

The sub-surface stress field beneath the spur gear's contact surface in lubricated condition has been analysed. The surface pressure was obtained by the elasto-hydrodynamic lubrication analysis using the accurate geometric clearances around the contact region of the teeth. The sub-surface stress field was calculated by using the Love's rectangular patch solution. The analysis results show that the sub-surface stress distribution is quite dependent on the surface pressure distribution. The pattern of sub-surface stress field is similar to that of the external load. The depth where the maximum effective stress occurs is not proportional to the intensity of the external load.

• 대한물리치료과학회지
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• 제11권4호
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• pp.29-37
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• 2004

Measurements of plantar pressure provide an indication of foot and ankle function during gait and other functional activities because the foot and ankle provide necessary support and flexibility for weight bearing and weight shifting while people are performing these activities. Plantar pressure is being increasingly used in both research and clinical practice to measure the effects of various footwear and physical therapy intervention. The influence of walking speed and ground inclination on plantar pressure parameters However has not been evaluated in detail. So, in this study to determine the effect of changes in walking speed and ground inclination on plantar pressure treadmills with different walking speeds and inclination were used. Plantar pressure parameters were measured with the Parotec system using the walking and running in 20 healthy participants(10 male, 10 female) aged $20{\sim}28$(mean 22.22, S.D.2.26 years) when slow walking and running. The result of this study with increased die walking speed, the peak pressure of 1st, 5th metatarsal head and total contact time and impulse total at the forefoot was affected by walking speed; however, die peak pressure, contact time and impulse total at the forefoot was not affected by ground inclination.

• PNF and Movement
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• 제11권2호
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• pp.95-102
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• 2013

Purpose : The purpose of this study was to investigate a plantar pressure distribution and the trajectory of the center of pressure on double limb support and single limb support according to level surface, air cushion, and aero step. Methods : 21 healthy adults participated in this study. The plantar pressure were assessed at three different surface conditions(on the level surface, air cushion, and aero step) on double limb support and single limb support. Testing orders were selected randomly. Results : Plantar pressure distribution show a significant difference contact area 1 and contact area 3 on double limb support and single limb support. The trajectory of the center of pressure show an significant difference anteroposterior(AP), mediolateral(ML), and total displacement on double limb support and single limb support. Conclusion : Through the use of soft surface as air cushion and aero step will be using the ankle strategy. This will be to strengthen the muscles around the ankle. Consequently, should help to improve stability and coordination.

• 대한의용생체공학회:의공학회지
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• 제18권4호
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• pp.439-446
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• 1997

증가하고 있는 주요 족부질환인 엄지발가락외반증의 특성을 이해하기 위하여 본 연구를 수행하였다.23명의 엄지발가락외반증 환자들에 관한 방사선학적 연구와 함께 자유보행시의 족저압력분포를 측정하였다. 또한 본 연구에서는 족저압력 분포를 상세히 분석하기 위한 해부학적으로 적절한 구역설정을 제시하였다. 족저압력분포를 측정한 결과, 엄지발가락외반증이 심한 환자일수록 중족골 부위의 압력, 접촉면 적과 시간, 충격량 등이 현저하게 증가함을 알 수 있었다. 엄지발가락외반증은 신발의 선정이 잘못됨에 의하는 경우가 적지 않았다. 족저압력집중은 족부질환에 있어서 매우 중요하므로, 신발의 설계에 있어서 적절한 족저압력분포를 고려하여야 한다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.251-257
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• 2000

A numerical simulation of the temperature rise for sliding surface in dry contact is based on Jaeger's formula combined with a calculated heat input. A gear tooth temperature analysis was performed. The pressure distribution has the Hertzian pressure distribution on the heat source. The heat partition factor is calculated along line of action. A Temperature distribution of tooth surface is calculated about before and after profile modification. A Temperature of addendum and deddendum in modified gear have reduced.