• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.771-778
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• 2009

We aimed to determine the effect of heel height on foot pressure by comparing and analyzing data on foot pressure in shoes with different heel heights. Qn the basis of a previous study, we selected 3cm and 7cm as the shoe heel heights preferred by female college students. We divided 10 female students into forefoot and hindfoot to measure vertical force, maximum pressure, and average pressure. The average pressure on the forefoot was higher and that on the hindfoot was lower in the case of 7cm high-heeled shoes. The maximum pressure on the forefoot was significantly higher in the case of the 7cm heel height (p<.05). The vertical force, maximum pressure, and average pressure on the hindfoot were also significantly higher in the case of the 7cm heel height (p<.05). The results showed that wearing 7cm high-heeled shoes exerted greater maximum pressure on the forefoot and greater vertical force, maximum pressure, and average pressure on the Hndfoot. This leads to increase in confining pressure caused by high pressure distribution over the forefoot and increase in the pressure on the hindfoot, which may cause deformation of toes and heel pain over a long period. Therefore, female college students who wish to wear high heels are recommended to wear 3cm high-heeled shoes rather than 7cm high-heeled shoes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.191-194
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• 2007

In hot embossing lithography which has shown to be a good method to fabricate polymeric patterns for IT and bio components, it is very important to determine the proper process conditions of pressure, temperature, and time. It is also a key factor for predicting the optical properties of final product to calculate residual stress distribution after the embossing process. Therefore, to design the optimum process with right conditions, the ability to predict viscoelastic behavior of polymer during and after the hot embossing process is required. The objective of the present investigation is to establish simulation technique based on constitutive modeling of polymer with experiments. To analyze deformation behavior of viscoelastic polymer, the large strain material properties were obtained from quasi-static compression tests at different strain rates and temperatures and also stress relaxation tests were executed. With this viscoelastic material model, finite element simulation of hot embossing was executed and stress distribution is obtained. Proper process pressure is very important to predict the defect and incomplete filling.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.93-98
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• 2015

This study focuses on simulation technology in the injection molding process for plastic optic lenses. The CAE program 3D TIMON was used to predict retardation, flow patterns and warpage deformation. The results were compared to the results of optic lenses as measured using the WPA-100 retardation measurement device with injection molding CAE for retardation predictions. According to the analysis and measured results, the distributions of retardation between the CAE results and the measurement results were similar. It was also confirmed that varying the injection speed had an effect on the injection pressure, warpage deformation and retardation distribution. As the injection speed increases, the injection pressure also increases and warpage deformation decreases. However, as the injection speed increases, the retardation distribution deteriorates.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.35-42
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• 2014

The influence of sine wave striated surface roughness on load carrying capacity of a bearing is studied for thin film effect of slider bearing. A Reynolds equation appropriate for slider bearing is used in this paper for analysis and it is discussed using finite difference method of central difference scheme. For a slider bearing with sine wave simple roughness form, several parameters such as pressure, load capacity and shear stress of the bearing can be obtained and also this results can be stored in sequential data file for latter analysis. After all, their distribution can be displayed and analyzed easily by using the matlab GUI technique. The parameters such as amplitude, number of waviness and slope of the surface are used for discussing the load carrying capacity of the rectangular bearing. The results reported in this paper should be applied to the other slider bearing such as rectangular or round embossed surface of slider bearing.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.337-343
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• 2012

Objective: The aim of this study was to determine the effect of abdominal-compression belt in one leg standing on balance in normal adult. Background: With the effects of increased intra-abdominal pressure, the abdominal-compression belt is contributing to a static balance control. However, specific study is still insufficient. Method: Forty subjects were randomly allocated to two groups: control(n=20) and experimental group(n=20), respectively. The experimental group used an abdominal-compression belt, whereas the control group did not that. All subjects were educated using pressure biofeedback unit and ultrasound imaging for exact application by abdominal-compression belt. Main outcome measurement was used a general stability index, fourier harmony index, weight distribution index, and fall index in tetrax balance system. Results: Experimental group improved significantly on general stability, only 2 factors(eyes closed with head turned forward and eyes closed with head turned backward) among fourier harmony index, and fall index, However, weight distribution index did not revealed significant difference. Conclusion: The findings suggest that application of abdominal-compression belt could be effective on improving balance ability in one leg standing of normal adults. Application: The results of the abdominal-compression belt might help to control balance in workers.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1975-1981
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• 1991

A new numerical solution of the elastohydrodynamic lubrication(EHL) problem of an axially profiled cylindrical roller is presented. A finite difference method and the Newton-Raphson method are used to solve the nonlinear system equations. A non-uniform grid system is adopted to reduce the number of grid points and to obtain accurate solution. For two different types of profiles which have similar elastostatic pressure distribution, the EHL results show large differences. Especially the difference in film shape is larger than in pressure distribution. Therefore, the magnitude of the minimum film thickness should be a major criteria to design the axial profile of the roller. Variations of the minimum film thickness with dimensionless parameters show considerably different behavior from those of infinite solution and show a good agreement with the experimental data in literatures. Present numerical scheme can be used generally in the analysis of three-dimensional EHL problem.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.105-111
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• 2000

Micronization of sensor is a trend of the silicon sensor development with regard to a piezoresistive silicon pressure sensor, the size of the pressure sensor diaphragm have become smaller year by year, and a microaccelerometer with a size less than 200~300${\mu}{\textrm}{m}$ has been realized. Over the past four or five years, numerical modeling of microsensors and microstructures has gradually been developed as a field of microelectromechanical system(MEMS) design process. In this paper, we study some of the micromachining processes of single crystal silicon(SCS) for the microaccelerometer, and their subsequent processes which might affect thermal and mechanical loads. The finite element method(FEM) has been a standard numerical modeling technique extensively utilized in structural engineering discipline for component design of microaccelerometer. Temperature rise sufficiently low at the suspended beams. Instead, larger temperature gradient can be seen at the bottom of paddle part. The center of paddle part becomes about 5~2$0^{\circ}C$ higher than the corner of paddle and suspended beam edges.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.67-74
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• 2006

An unsteady blockage-correction method utilizing wall pressure distribution on the test section has been developed for the wall interference correction of a closed test-section subsonic wind tunnel. The pressure distribution along the test section wall was decomposed into Fourier series and a quasi-steady method based on a measured-boundary-condition method was applied to each Fourier coefficient. The unsteady correction for a complete test period was accomplished by recombining each corrected terms. The present method was validated by appling computed unsteady flows over a cylinder and an oscillating airfoil in the test sections. The corrected results by the present method agreed well with free-air condition.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.137-142
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• 2002

The fluid mechanics and operating conditions of gas-lubricated proceeding bearings in micro rotating machinery such as micro polarization modulator and micro gas turbine are different from their larger size ones. Due to non-continuum effects, there is a slip of gas at the walls. Thus in this paper, the slip flow effect is considered to estimate the pressure distribution and load-carrying capacity of micro gas-lubricated proceeding bearings as the local Knudsen number at the minimum film thickness is greater than 0.01. Based on the compressible Reynolds equation with slip flow, the static characteristics of micro gas-lubricated proceeding bearings are obtained. Numerical predictions compare the pressure distribution and load capacity considering slip flow with the performance of micro proceeding bearings without slip f]ow for a range of bearing numbers and eccentricities. The results clearly show that the slip flow effect on the static characteristics is considerable and becomes more significant as temperature increases.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.626-629
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• 2003

This study is to forecast possible occurrence of internal condensation around parpets and H-beam located at the inside of balcony ceilings on the uppermost floor of super-high apartment buildings faced with open air in order to provide dwellers with more comfortable environment in the related space and get rid of their uneasiness about the condensation. In this study, we estimated internal condensation. which vary in accordance with humidity pressure distribution, at curtain walls, stone panels or lower parts of slabs that constitute outer space of the residence and are weak against heat, through temperature forecast and temperature distribution interpretation program at normal two-dimension temperature.