• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.1
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• pp.45-50
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• 2021

Machines and facilities are physically or chemically degenerated by continuous usage. The representative type of the degeneration is the wearing of tools, which results in the process mean shift. According to the increasing wear level, non-conforming products cost and quality loss cost are increasing simultaneously. Therefore, a preventive maintenance is necessary at some point. The problem of determining the maintenance period (or wear limit) which minimizes the total cost is called the 'process mean shift problem'. The total cost includes three items: maintenance cost (or adjustment cost), non-conforming cost due to the non-conforming products, and quality loss cost due to the difference between the process target value and the product characteristic value among the conforming products. In this study, we set the production volume as a decreasing function rather than a constant. Also we treat the process variance as a function to the increasing wear rather than a constant. To the quality loss function, we adopted the Cpm+, which is the left and right asymmetric process capability index based on the process target value. These can more reflect the production site. In this study, we presented a more extensive maintenance model compared to previous studies, by integrating the items mentioned above. The objective equation of this model is the total cost per unit wear. The determining variables are the wear limit and the initial process setting position that minimize the objective equation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1033-1038
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• 2014

Electric vehicles should be connected to power system for charge and discharge of battery. Besides vehicle's battery is charged for a power source, it is also reversibly possible to provide power source from battery to power system. Researches on battery usage for regulation resources have been progressed and could cause cost increase excessively because they distribute regulation capacity equally without considering the battery wear cost of SOC, temperature, voltage and so on. This causes increase of grid maintenance cost and aggravate economical efficiency. In this paper it is studied that the cost could be minimized according to the battery condition and characteristic. The equation is developed in this paper to calculate the possible number of charge and discharge cycle, according to SOC level and weighting factors representing the relation between battery life and temperature as well as voltage. Thereafter, the correlation is inferred between the battery condition and wear cost reflecting the battery price, and the expense of compensation is decided according to the condition on battery wear-out of vehicle. In addition, using realtime error between load and load expectation, it is calculated how much regulation capacity should be provided.

• The Research Journal of the Costume Culture
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• v.16 no.4
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• pp.681-695
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• 2008

This study was accomplished to investigate the preference of clothing materials and the clothing demand performance for underwear and everyday dress of atopic patients. As this study was the research study by a use of a questionnaire, the finally total 987 copies of the collected questionnaires were used to analyze the data. SPSS was used for the statistical analysis of data. To analyze the data, frequency analysis, percentage, $X^2$-test, reliability analysis, factor analysis, t-test, ANOVA and Duncan's multiple comparisons were used. The results obtained are as follows. In factor analysis for clothing materials and the demand performance which atopic patients favor, the preference factors for underwear materials were classified as pliability/a sense of weight, a sense of cold and warmth, tactility, and elasticity. Those for everyday wear were classified as pliability/surface roughness, a sense of cold and warmth, a sense of weight, and elasticity. And the demand performance factors for underwears were classified as thermophysiology, care convenience, and skin contact. Those for everyday wear were classified as comfortableness and care convenience. In the difference analysis for the preference and the demand performance, Both everyday wear and underwear showed a significant difference for the preference and the demand performance according to gender, age, income, education level, and occupation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.526-530
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• 1996

In this paper, three different types of commercially tools-P20, NC123K and ceramic-have been used to working austempered ductile iron(ADI). In the austempered condition the materials are hard, strong and difficult to machine. Thus, we selected a optimum tool material among three different types of used tools in machining of austempered ductile iron. It was used acoustic emission(AE) to know cutting characteristic for selected tool and flank wear land of the ceramic too. The obtained results are as follows; (1) The ceramic tool among three different types of tools is the best in machining austempered ductile iron. (2) In case of ceramic tool, the amplitude level of AE signal(AErms) is mainly affected bycutting speed in cutting speed in cutting condition and it is proportioned to cutting speed. (3) There have the relationship of direct proportion between the amplitude level of AE signal and flank wear land of the tool. (4) If it find the value of AErms at each cutting speed, the in-process detection to ceramic tool's wear is possible

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.9_10 s.146
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• pp.1253-1264
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• 2005

The background, concept, and design characteristics of the Caports style, which comes into new domestic fashion trend of sportism, are discussed in this article. Analysis are performed with utilizing pictures, advertizements of fashion magazine such as Vogue Korea, Fashionbiz, Ceci, etc., and photographs from internet sites, domestic papers since 2002. The result of this study is as followings: New life style, arose from the change of social and cultural environment, such as increase in leisure time, fusion and well-being trend, begins to be reflected in caports style in the form of stress on utility and functionality. The caports style is a fusion style based on sports wear with character and fashion. And, it can be adapted as a sports wear and daytime wear. With respect to the form, it emphasizes healthy body line, and as for the material, it strikingly utilizes various and functional materials. It also shows active and cheerful image using bright color, and utilizes functional and decorative details such as line-tape, zipper, hood. The most important characteristic of the caports style is to present a new liberal style by mix & match, layering, and exposing

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.14-21
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• 2003

This study deals with the influence of ceramic coating on characteristics of friction and abrasion of aluminum allot(7075 T6) used in mechanical casting. In this research, frictional wear characteristic of ceramic coating materials such as $A1_2O_3$, $Si_3N_4$, SiC was investigated using aluminum alloy(7075 T6) and stainless 403 cast iron under room temperature and normal air pressure. The coating layer was observed using SEM. The conclusions are as follows: 1) Friction coefficients of $A1_2O_3$, SiC and $Si_3N_4$ are obtained 0.63 0.56 and 0.54 respectively. 2) Abrasion resistance of stainless 403 cast iron with $Si_3N_4$ is the best among the ceramic coating materials. 3) Abrasion mechanism of aluminum alloy(7075 T6) coaled with ceramic material and stainless 403 cast iron is caused by brittle fracture. 4) Coating the ceramic material on the aluminum alloy(7075 T6) can effectively increase the antiwear, impact properties, and corrosion resistance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.231-234
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• 2004

Chemical mechanical polishing(CMP) process was studied in terms of tribology in this paper. CMP performed by the down force and the relative motion of pad and wafer with the slurry is typically tribological system composed of friction, wear and lubrication. The piezoelectric quartz sensor for friction force measurement was installed and the friction force was detected during CMP process. Various coefficient of friction was attained and analyzed with the kind of pad, abrasive and the abrasive concentration. The lubrication regime is also classified with ${\eta}v/p(\eta,\;v\;and\;p;$ the viscosity, relative velocity and pressure). Especially, the co-relation not only between the friction force and the removal per unit distance but also between the coefficient of friction and within-wafer-nonuniformity was estimated.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.6
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• pp.1021-1030
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• 1997

Physical variables related to the subjective evaluation of wear comfort were explored. Experimental fabrics was those used in the previous paper where subjective sensations of women's thin shirts were reported. Fabrics include 100% cotton (unfinished), 100% cotton (water repellent finished), cotton/polyester 35/65 (unfinished), cotton/polyester 35/65 (peach skin finished), 100% polyester fabric(plain), 100% polyester crepe. Among various physical properties of the experimental fabrics, heat 8E moisture transport properties and surface properties were chosen as important variables based on the regression coefficient. Especially, humidity at the microclimate in dynamic mode was highly correlated to the subjective evaluation and appeared to be a sensitive physical predictor, compared to dry thermal transmission rate or water vapor transmission rate. Surface characteristic parameters, however, did not show consistant trend in the prediction of the human's subjective sensation. Interaction between surface properties and humidity measurement was also observed.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.5
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• pp.772-783
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• 2000

The purpose of this study was to investigate product evaluation on consumer's buying behavior of domestic & imported golf wear brands. The questionnaires were sent to 200 consumers who play golf. The 119 data were analyzed by mean, t-test, ANOVA and chi-square. The results of the study were as follows: There were significant differences on consumers' evaluation of apparel quality on fabric and style between groups. Consumers evaluated that the imported golf wears made of more soft, light and unique fabric than domestic, and had a unique and characteristic style. The evaluation of apparel quality according to demographic information has significant difference. Consumers(46-55 ages, business managers and professional) evaluated imported brands were made of soft and light fabric. Consumers(business managers) buying imported brand evaluated dry-cleaning was inconvenient. Consumers who engaged in service industry evaluated domestic brands were easy to coordinate with other items.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1571-1574
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• 2005

Generally, the kerosene or the deionized water has been used for dielectric fluid in the electrical discharge machining. The spark occurs when the voltage is over the breakdown voltage and induces high temperature. In this study, the Oxygen gas is used as the dielectric. The voltage behavior in the dry Micro Electrical discharge machining is compared with that of the conventional Micro Electrical discharge machining. The dry Micro EDM has some advantages. The electrode wear isvery smaller than that of the conventional Micro EDM. The contamination in the dry Micro EDM can be drastically reduced comparing to that of the conventional Micro EDM. The Oxygen gas can be replaced as the dielectric successfully.