• Journal of Fashion Business
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• v.11 no.6
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• pp.35-51
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• 2007

This research was administered in order to know the effects of heels on the foot by comparing the foot environmental characteristics when common shoes and elevated shoes are worn. First, 157 male adults in their 20s through 40s living in Busan were the inquiry subjects to reveal the shoes-wearing reality of adult males. Second, 7 male adults in their early 20s became the subjects for the experiments of wearing common shoes and elevated shoes. 1. Inquiry Results of Shoes-Wearing Reality Common-shoes wearers were in the order: 20s (43.9%) > 30s (24.8%) > 40s (8.3%). Elevated-shoes wearers were mostly 20s (12.1%), followed by 30s (8.3%) and 40s (2.5%). Among the wearing effects of elevated shoes were 'looking taller' (66.7%), 'no height complex & more confidence' (30.6%), and 'higher work efficiency' (2.8%). In sum, 97.3% of the male subjects believed in great positive effects by wearing elevated shoes. 2. Shoes-Wearing Experiment Results In foot skin temperature, significant differences between the two groups were admitted in outer foot a (p<0.05) and other areas (p<0.001), except in the instep. Elevated-shoes group had bigger skin temperature, while the order of temperature was the instep, the big toe, inner foot a/b/c and outer foot a/b/c. Significant difference was accepted in total sweat rate (p<0.05) and local sweat rate (p<0.01). Elevated-shoes group appeared higher in both rates. Significant difference (p<0.001) between the two groups was recognized in fatigue degrees after wearing, whereas significance (p<0.05) in elevated-shoes group was approved in fatigue before and after exercise. So elevated-shoes group experienced more fatigue, especially after exercise.

• Journal of Korea Game Society
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• v.13 no.3
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• pp.5-18
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• 2013

This study analyzed the effect by comparing it with 2D game using playtest experimental treatment methodology to verify the video effect, materiality and fatigue effect of 3D video game. First, for the hypothesis to verify the difference of video experience of users for 3D and 2D games, visual clarity was rejected, but materiality, tangibility and presence hypotheses were all accepted. Second, it was shown that there was no difference in eye fatigue and physical fatigue in 3D and 2D games. It was different from results of existing research which claimed that fatigue occurred due to video distortion occurring in 3D video and fatigue inducing factors. Third, the results of measurement of changes in brain wave occurring in the course of playing 3D and 2D games showed that there was no difference in average amplitude of EEG alpha wave, but EEG beta wave occurred in higher amplitude. This study proved the cerebral physiological change and difference in the process of experience to use 3D video game by complementing the methodology in measurement in EEG brain wave in the traditional experimental method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.108-116
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• 2014

The proper stress history measurement should be conducted in order to examine the accurate cause of fatigue cracks or the fatigue safety in the steel bridge. Only one strain gauge is generally installed in the field for the stress history examination because of the field circumstances, economic feasibility, workability, and so on. However, this method may not consider the actual size of the specific structure, the gauge length, and the affect of stress concentration in the welded joint. In addition, it is difficult to apply for the stress analysis. Therefore, this study suggests improvements that are a great number of gauge installations, the gauge location adjustment, and the use of the minimum length gauge. It is drived the correlative equation of strain for the distance between the welding toe and the strain gauge installation, and compare correlative equation with equation of IIW. Also, this study could estimate the remaining life and fatigue damage of bridge in service by selecting the suitable stress category. In conclusion, it is possible to understand the member which is high in the fatigue cracks, and the quantitative relations between the welding toe and the strain gauge installation distances. The proposed approach in this study can make an more accurate fatigue damage and a remaining life prediction so that the improved method should be applied in measuring the strain of bridges from now on.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.5
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• pp.532-538
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• 2002

This study was performed to classify the fatigue crack opening and closure for three kinds of aluminum alloy using principal component analysis (PCA). Fatigue cycle loading test was conducted to acquire AE signals which come from different source mechanisms such as crack opening and closure, rubbing, fretting etc. To extract the significant feature from AE signal, correlation analysis was performed. Over 94% of the variance of AE parameters could accounted for the first two principal components. The results of the PCA on AE parameters showed that the first principal component was associated with the size of AE signals and the second principal component was associated with the shape of AE signals. An artificial neural network (ANN) an analysis was successfully used to classify AE signals into six classes. The ANN classifier based on PCA appeared to be a promising tool to classify AE signals for fatigue crack opening and closure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.134-137
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• 2008

The effects of residual stress and surface defects on the mechanical properties of the high carbon steel filament used for the automotive tire have been experimentally investigated. The samples were fabricated with annealing temperature. The residual stress was measured by focused ion beam and strain mapping software which has advantages, such as data with high accuracy and fast data acquisition time. Mechanical properties, such as tensile strength and fatigue resistance, were gradually increased up to $200^{\circ}C$ and then slightly decreased. From the measurement of residual stress and level of surface defect, it was revealed that the critical factor was varied with different temperature region. That is, the fatigue resistance increased due to decreasing the residual stress and decreased due to increasing the size and distribution of surface defect.

• Journal of Welding and Joining
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• v.18 no.1
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• pp.52-58
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• 2000

Spot welding, namely a kind of electric resisting welding has been used widely in field of automobile and aircraft industries because of easiness to apply. Specimens used in this study was a mild steel of 1.2mm thickness and the electrode was a Cu-Cr alloy of 6mm diameter. The surface sheared of specimens after testing of tensile shear was observed by SEM(scanning electron microscope) after ultrasonic cleaning for 10min., and microstructures and grain size of all specimens were measured with using of O.M.(Optical microscope). By the means of measurement and observations of tensile shear load, fatigue strength and share surface, the weldability of spot welding was evaluated. When tensile shearing testing, fracture starting point in all specimens was took place at the bond between HAZ(Heat affected zone) and nugget. With increasing in number of layers, fatigue strength was decreased. With increasing in electric current, grain size in the HAZ became more fine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.163-168
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• 2006

In a micro-unit of electronic-machine, vibration can be excited by a small impact, and this vibration acts as a fatigue load. To measure the vibration effect on the micro unit, a micro dynamic tester is needed to test a micro specimen. In this paper, it has confirmed a movement of the PZT(piezo actuator) to use a sine signal. And, it has confirmed a fracture of specimens by using a tension-tension input signal in PZT. A metal-material property in the micro scale has been tested to compare with the macro scale. A fatigue test has been conducted by using PZT actuator to give a bending-tension effect.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.479-487
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• 2007

Die life is generally estimated taking failure life and wear amount into consideration. In this study, the forging die life was investigated considering both of these two factors. The fatigue life prediction for the die was performed using the stress-life method, i.e. Goodman's and Gerber's equations. The Archard's wear model was used in the wear life simulation. These die life prediction techniques were applied to the die used in the forging process of the socket ball joint of a transportation system. A rigid-plastic finite element analysis for the die forging process of the socket ball was carried out and also the elastic stress analysis for the die set was performed in order to get basic data for the die fatigue life prediction. The wear volume of the die was measured using a 3-dimensional measurement apparatus. The simulation results were relatively in good agreement with the experimental measurements.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.378-383
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• 2008

Bogie frame of the locomotive is an important structural member for the support of vehicle loading. A lot of study has been carried out for the prediction of the structural integrity of the bogie frame in experimental and theoretical domains. The objective of this paper is to estimate the structural integrity of the bogie frame. Strength analysis has been performed by finite element analysis. From these analysis, stress concentration areas were investigated. For evaluation of the loading conditions, dynamic stress were measured by using strain gage. It has been found that the stress and strain due to the applied loads were multi-axial condition according to the location of strain gage. The fatigue strength evaluations of the bogie frame are performed to investigate the effect of the multi-axial load through the employment of the critical plane approach.

• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.3
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• pp.197-203
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• 1982

The fatigue crack propagation behavior or non-heat-treatment and thermally aged type 304 stainless steel was investigated on the basis of linear elastic fracture mechanics. This Study was concentrated on the relations between the crack propagation rate and the stress intensity factor range. The following results are obtained : The precision measurement and observation of fatigue crack propagation behavior is studied with moire grating. The effect of thermally aged type 304 stainless steel is investigated under small load. In the equation da/dN=c(.DELTA. k)/SUP m/, factor m of thermally aged steel is a little higher than non-heat-treatmented steel and its limit is m=1.35-4.2.