• Journal of Korean Institute of Industrial Engineers
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• v.19 no.2
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• pp.53-64
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• 1993

Successful completion of a visual task in a predetermined time is very crucial to many operations such as piloting an aircraft. Although existing ergonomic interface models often provide a function of vision tests, it determines only the visibility at any given location. To complement this problem in existing models, the isoresponse time region considering the factors related to visual tasks is presented. Using a multiple regression model, equal response time regions were obtained within which mean response time is expected to be the same and is asymmetrical in shape. Among the factors considered, expectancy significantly decreased response time, and when cued, the effects of field heterogeneity, target uncertainty, density, size contrast and peripheral position on search time were less significant than those in unexpected cases. Response time and error rate, gender and visual acuity were not significantly correlated, and response time and age was positively correlated. These results are expected to be directly applicable to designing various visual tasks in real-life situations.

• Structural Engineering and Mechanics
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• v.68 no.2
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• pp.237-245
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• 2018

This study proposes an empirical formulation to predict the maximum deformation of offshore blast wall structure that is subjected to impact loading caused by hydrocarbon explosion. The blast wall model is assumed to be supported by a simply-supported boundary condition and corrugated panel is modelled. In total, 1,620 cases of LS-DYNA simulations were conducted to predict the maximum deformation of blast wall, and they were then used as input data for the development of the empirical formulation by regression analysis. Stainless steel was employed as materials and the strain rate effect was also taken into account. For the development of empirical formulation, a wide range of parametric studies were conducted by considering the main design parameters for corrugated panel, such as geometric properties (corrugation angle, breadth, height and thickness) and load profiles (peak pressure and time). In the case of the blast profile, idealised triangular shape is assumed. It is expected that the obtained empirical formulation will be useful for structural designers to predict maximum deformation of blast wall installed in offshore topside structures in the early design stage.

• Journal of Biosystems Engineering
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• v.33 no.5
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• pp.296-302
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• 2008

The effective moisture diffusivity and its dependence on drying temperature during drying of rapeseed were experimentally investigated. The data were recorded from thin layer drying experiments at nine different combinations of drying air temperatures of 40, 50, and $60^{\circ}C$ and the relative humidities of 30, 45, and 60%. The moisture diffusion equation was analyzed using stepwise multiple regression analysis. Effective moisture diffusivities were calculated based on the moisture diffusion equation for a spherical shape using Fick's second law. The effective diffusivities during the drying of rapeseed were $l.72{\times}10^{-11}$, $2.41{\times}10^{-11}$ and $3.31{\times}10^{-11}\;m^2{\cdot}s^{-1}$ at 40, 50 and $60^{\circ}C$, respectively. The activation energy for moisture diffusion during drying was $28.47\;kJ{\cdot}mol^{-1}$. The dependence of moisture diffusivity on temperature was described by an Arrhenius-type equation. Drying occurred in the falling rate period and the internal moisture diffusion phenomenon is the governing physical mechanism of the moisture movement in the particles.

• Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.63-70
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• 2016

Deep drawing is a forming process in which a blank of sheet metal is radially drawn into a forming die by the mechanical action of a punch and converted to required shape. Deep drawing involves complex material flow conditions and force distributions. Radial drawing stresses and tangential compressive stresses are induced in flange region due to the material retention property. These compressive stresses result in wrinkling phenomenon in flange region. Normally blank holder is applied for restricting wrinkles. Tensile stresses in radial direction initiate thinning in the wall region of cup. The thinning results into cracking or fracture. The finite element method is widely applied worldwide to simulate the deep drawing process. For real-life simulations of deep drawing process an accurate numerical model, as well as an accurate description of material behavior and contact conditions, is necessary. The finite element method is a powerful tool to predict material thinning deformations before prototypes are made. The proposed innovative methodology combines two techniques for prediction and optimization of thinning in automotive sealing cover. Taguchi design of experiments and analysis of variance has been applied to analyze the influencing process parameters on Thinning. Mathematical relations have been developed to correlate input process parameters and Thinning. Optimization problem has been formulated for thinning and Genetic Algorithm has been applied for optimization. Experimental validation of results proves the applicability of newly proposed approach. The optimized component when manufactured is observed to be safe, no thinning or fracture is observed.

• Journal of the Korean Home Economics Association
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• v.23 no.4
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• pp.33-54
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• 1985

The purpose of this study is to establish the suitable wearing standard under environmental thermal conditions in Pusan. The data is obtained from 50 girl students from April, 1984 to March, 1985. Items of the research are as follows : Environmental conditioni, clothing weight, contents of wearing, clothing climate, wearing order etc. RESULTS : 1. The upper clothing wights are varied considerably with temperature, while the lower are not. 2. The outdoor temperature and the total clothing weights show the high negative correlation of r=-.97 wth regression equation of Y=-37.64X+1692.66. 3. The clothing weight per clo is 390g/$m^2$. 4. Mostly, subjects were 2~7kinds of the upper and 3~5kinds of the lower clothing. 5. The clothing weights on the upper part of the body are heavier than those on the lower part of it. 6. The standard deviation of the obver clothing is larger than that of the under clothing. 7. The clothing shape of comfort-sensation reporter changes with variation of temperature. 8. The clothing climate of the inner layer is 32.26$\pm$$0.5^{\circ}C$ in temperature, 43.6$\pm$7% in humidity at four seasons. 9. It is represented that total subjects and comfort-sensation reporter control the wearing contents suitably for temperature. 10. The standard of wearing in Pusan is established as Fig. 6.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.71-76
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• 2007

The fatalities of pedestrian account for about 40.0% of all fatalities in Korea 2005. Vehicle-Pedestrian accident generates trajectory of pedestrian. In pedestrian involved accident, the most important data to inspect accident is throw distance of pedestrian. The throw distance of pedestrian can be influenced by many variables. The variables that influence trajectory of pedestrian can be classified into vehicular factors, pedestrian factors, and road factors. Vehicular factors are the frontal shape of vehicle, impact speed of vehicle, the offset of impact point. Many studies have been done about the relation between impact speed and throw distance of pedestrian. But the influence of the offset of impact point was neglected. The influence of the offset of impact point was analyzed by Working Model, and the trajectory of pedestrian, dynamic characteristics of multi-body were analyzed by PC-CRASH, a kinetic analysis program for a traffic accident. Based on the results, the increase of offset reduced the throw distance of pedestrian. However box type vehicle just like bus, the offset of impact point did not influence the throw distance of pedestrian considerably.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.268-274
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• 2013

Electric discharge machining drill (EDM-drill) is an efficient process for the fabrication of micro-diameter deep metal hole. As there is non-physical contact between tool (electrode) and workpiece, EDM-drill is widely used to machine the hard machining materials such as high strength steel, cemented carbide, titanium alloys. The electro-thermal energy forces the electrode to wear out together with the workpiece to be machined. The electrode wear occurs inside of a machining hole. and It causes hard to monitor the machining state, which leads the productivity and the quality to decrease. Thus, this study presents a methodology to estimated the electrode wear amount while two coefficients (scale factor and shape factor) of the logarithmic regression model are evaluated from the experiment result. To increase the accuracy of estimation model, the linear transformation method is adopted using the differences of initial electrode wear differences. The estimation model is verified through experiment. The experimental result shows that within minute error, the estimation model is able to predict accurately.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.806-813
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• 2016

To alleviate the vibration problem or to satisfy the required criteria for manifesting the guaranteed performance of precise equipment, various vibration isolation materials or apparatus, such as viscoelastic material, air and coil spring, have been developed and applied. Among them, a wire mesh material is regarded as one of the good candidate for reducing the vibration in terms of moderate material price, easy shape machining and long life cycle without the property deterioration induced by the aging or environmental effects. In this paper, prior to wire mesh isolator design, the static and dynamic elastic modulus of wire mesh materials are extracted from the experiment by the simple shaped cylindrical specimens and their characteristics for applying to vibration isolator design are examined. The simple shaped specimens were made as considering the design parameters of a wire mesh mount; i.e. the density, wire diameter and wire mesh slope, and the sensitivity analysis were also performed from a view point of the extracted elastic modulus.

• Journal of the Korea Safety Management & Science
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• v.16 no.3
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• pp.219-229
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• 2014

Employees used computer significantly(IT employee) is increased by technological development in workplace. This study tried to find the magnitude of IT employees and the profile of their working conditions and ill health experiences in South Korea. Korean Working Conditions Survey was used with descriptive and mean difference test in order to find the difference working conditions and ill health status among the groups classified by the degree of using computer during work. Some of working conditions was positively correlated with the density of computer use such as work autonomy, the exposure of repetitive movement of hand and arms. The pain of upper extreme was also more frequently found in the highest user group of computer than lower user groups. Based on the result of hierarchical regression analysis, the effect of computer using on the experience of work-related symptoms after controlling other factors was shown as U shape. This study as heuristic one suggest that some of depth analysis with hypothesis will be done to identify the causes and pathway of impact of computer use.

• Journal of Sasang Constitutional Medicine
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• v.32 no.1
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• pp.30-38
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• 2020

Objectives The purpose of this study is to reduce the question items in Korea Sasang Constitutional Diagnostic Questionnaire (KS-15) and to assess the validity. Methods The subjects of this study were 1,553 people who had information on body shape, personality, and symptoms among the data established at the Korean Medicine Data Center. Among them, 155 people were separated into a test group to assess the validity, and the remaining 1,398 were used as training groups for model development. The reduction question items were finally confirmed through discussion by two experts. The model development went through Multinomial Logistic Regression. Results & Conclusions The Percent Correctly Predicted (PCP) in the test group was 60.00% (58.49% in men and 60.78% in women). The PCP of each constitution was 72.6% in Taeeumin, 53.3% in Soeumin, and 50% in Soyangin. The accuracy rate of KS-10 seems to be reasonable considering the ease of use of reduced time required.