• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.785-791
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• 2000

GDI (Gasoline Direct Injection) engines are considered as one of the candidates for next generation engines of passenger cars, which reduce exhaust emissions and fuel consumption. In GOI engines, a high-pressure gasoline supply system is required to directly inject the fuel to combustion chambers. Because of low lubricity of gasoline fuel, the clearance between a plunger and a barrel in GDI fuel pumps is too wide to achieve smooth hydrodynamic lubrication. Thus, it is difficult to generate high-pressure condition in GDI fuel pump since large amount of leakage flow occurs between the plunger and the barrel In this study, an optimum plunger design is presented to minimize leakage in the aspect of flow control. This paper analyzes leakage flow characteristics in the clearance to improve pumping performance of GDI fuel pumps. Effects of groove in the plunger are studied according to variations of depth and width. Evaluations of pumping performance are determined by the amount of pressure drop in the leakage path assuming a constant leakage flows. Both of turbulence and incompressible models are introduced in CFD (Computational Fluid Dynamics) analysis. Design parameters have been introduced to minimize leakage in limited space, and a methodological study on geometrical optimization has been conducted. As results of CFD analysis in various geometrical cases, optimum groove depths have been found to generate maximum sealing effects on gasoline fuel between the plunger and the barrel. This procedure offers a methodological way of an enhancement of plunger design for high-pressure GDI fuel pumps.

• Journal of Fashion Business
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• v.20 no.5
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• pp.45-59
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• 2016

This research is a study to develop basic block patterns for adult males. The subjects were 20 men in their 20s, and we tested 6 basic bodice blocks that are used in academia and industry. First, a comparative analysis of the patterns of the bodice blocks was conducted and the test garments were made, and then their appearances were evaluated during wearing tests. Based on the test results, we intended to select a bodice block that is a good fit when it is put on and to use it as basic data in order to design a man's bodice block for the future. The research results are as follows: First, a comparison of the 6 bodice block drafts showed that they used differently calculated ease allowances at chest circumference and width, waist circumference, shoulder length, etc. for which the upper chest circumference is used as a reference. Second, when the appearances of the test garments were tested, the average scores were high in the order of B> H> P> K> M> L. Pattern B was superior in the areas of the neck circumference and shape, ease allowance at the back of the neck, circumference of the front of the neck, location of side width, ease allowance at sides, armhole width and depth. But in the other test items, there were cases where other patterns were superior.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.1
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• pp.10-19
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• 2008

To investigate the effect of ultrasonic nano-crystalline surface modification (UNSM) treatment on rolling contact fatigue and residual stress properties of bearing steels, this paper carried out a rolling contact fatigue test, measured residual stress and retained austenite, performed a wear test, observed microstructure, measured micro hardness, and analyzed surface topology. After the UNSM treatment, it was found that the surface became minute by over $100{\mu}m$. The micro surface hardness was changed from Hv730~740 of base material to Hv850~880 with about 20% improvement, and hardening depth was about 1.3 mm. The compressive residual stress was measured as high as -700~-900 MPa, and the quantity of retained austenite was reduced to 27% from 34%. The polymet RCF-6 ball type rolling contact fatigue test showed over 4 times longer fatigue lifetime after the UNSM treatment under 551 kgf load and 8,000 rpm. In addition, this paper observed the samples, which went through the rolling contact fatigue test, with OM and SEM, and it was found that the samples had a spalling phenomenon (the race way is decentralized) after the UNSM treatment. However, before the treatment, the samples had excessive spalling and complete exploration. Comparison of the test samples before and after the UNSM treatment showed a big difference in the fatigue lifetime, which seems to result from the complicated effects of micro particles, compressive residual stress, retained austenite, and surface topology.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.7
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• pp.983-994
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• 2004

The aim of this study is to provide fundamental data on the development of ready-to-wear clothes appropriate for the body types of elderly women. The study was conducted targeting 318 elderly women over 60 years of age whose fields of action were colleges for the elderly, sports centers, or business sites in Seoul and the neighboring districts. A total of 44 features in the upper body were used for the anthropometric measurement and analysis using anthropometry and photometry. The results of the study are as follows: 1. Somatotypes were classified into three types according to a cluster analysis using height and weight indices. Type 1 is the group with long and undersized upper body and straight body type since the face of the upper body is long relative to height and width, girth and depth are the smallest relative to weight, the breasts are somewhat fat, with a small extent of drooping and a straight back. Type 2 is the group that is considered fat relative to the body, has broad shoulders, drooping breasts with a wide space between them, and a back-bent upper body. Type 3 is the group that has a bent shape, the shortest upper body relative to height, and showing average obesity factors. 2. Indices of height and weight were used for factor analysis, cluster analysis, and discriminant analysis in order to classify upper body somatotype according to shape while excluding size factors of elderly women＇s upper body somatotype. The same method was used to compare and verify the result according to the absolute measurement and height index. Classification based on height and weight indices demonstrate that such somatotype classification minimizes the personal equation of body shape and it induces better classification based on shape as the results showed the highest cumulative sum of square(CUSUM) at 78.38% while six factors showed the smallest result and the hit rate for the classified three groups showed the highest result at 95.30%.

• Journal of the Korean Society of Costume
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• v.54 no.8
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• pp.1-14
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• 2004

The aim of this study is to provide fundamental data on the development of ready-to-wear clothing appropriate for the lower body types of male students who play sports in college. The study was conducted by means of targeting 151 male sports majors between $18{\sim}27$ years of age. Characteristics of the respondents were ascertained by means of questionnaires and an evaluation of a total of 36 lower body features. The results of the study are as follows. 1. A comparison of anthropometric measurements with the National Anthropometric Survey of Korea (1997) revealed that the main characteristics of the lower somatotypes of male sports college students are large circumferences and developed muscles of the lower body. 2. Sports were classified into the following five categories : soccer, bodybuilding, wrestling, judo, and taekwondo. In particular, bodybuilding students demonstrated a somatotype with an increased circumference, depth, and width of the thigh and lower body. 3. Somatotypes were classified into 3 types by means of a cluster analysis employing S factors. Type 1 somatotype exhibits a large circumference in the lower body. Type 2 is a lower somatotype of a middle size. Finally, Type 3 encompasses a smaller group in weight and circumference with a developed calf and ankle. 4. Each group was evaluated using a discriminatory analysis as a check to see if the groups had been discriminated with accuracy. The total accuracy rate was 96.0%.

• Journal of Welding and Joining
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• v.26 no.4
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• pp.85-91
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• 2008

The grooving corrosion is caused mainly by the different microstructures between the matrix and weld which is formed during the rapid heating and cooling cycle in welding. By this localized corrosion reaction of pipes, it evolves economic problems such as the early damage of industrial facilities and pipe lines of apartment, and water pollution. So lots of researches were carried out already about grooving corrosion mechanism of ERW carbon steel pipe but there is seldom study for water hammer happened by fluid phenomenon and corrosion rate by flow velocity. In this study, the analysis based on hydrodynamic and fracture mechanics was carried out. ANSYS, FLUENT and STAR-CD were used for confirmation of flow phenomenon and stress on the pipe. As the results, fatigue failure is able to be happened by water hammer and grooving corrosion rate is increased cause by turbulent. Grooving corrosion is happened on the pipe, then friction loss of fluid is occurred from corroded part. Erosion can be happened enough in corroded region of microscopic size that wear "V" form. Also pipe is able to be damaged by water hammer effects because of corroded region is general acting as a notch effects. Corrosion depth was more than half of total thickness, it can be damaged from water hammer pressure.

• Proceedings of the Korean Vacuum Society Conference
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• 1995.06a
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• pp.154-154
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• 1995

The Xu-Tec process is also called the double glow surface alloying technology and is a new method of surface metallurgy which can produce an alloy layers with sp ecial phisical and chemical properties on the surface of common and inexpensive mater ials. Many super alloys and alloy steels, sueh as nickel base alloys, high speed steels and staiinless steels, have been produced by Xu-Tee Process on the surfaces of carbon steels. The depth of the alloy lasyers may vary from several microns up to 300 micr ons with alloying elements in a concentration of few percentage to 100%. World wide patents for Xu-Tec process have been granted in the United states, Canada, United Ki ngdom, Australia and Japan. High performance saw blades have been successfully produced by the Xu-Tee process with much simper processing steps and less cost than bimetal high speed saw blades. A comparison of the cutting times and wear rates of the Xu-Tee blades with the conventional bimetal blades has been made. The Xu-Tee bIases demonstrates sim ilar or better performance than bimetal blades. A Xu-Tec Unit for the commercial pr oduction of Xu-Tec saw blades has been designed and manufactured. This Unit can t reat 10,000 haek saw blades at one time. Three Xu-Tec hack saw blades production I ines have been set up in China. China.

• Journal of the Korean Home Economics Association
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• v.20 no.4
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• pp.53-67
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• 1982

Physical measurements of 181 Korean elderly women, aged 60 through 79, living in the Seoul area, were taken in 1981 in order to analyze their body types and to study clothing construction according to their body types. The study was composed of 117 items in all; 35 items in measurements, 1 items in Rohrer index, 68 items in physical index to stature and bust girth, and 14 items in proportion, Coefficients of correlation among body dimensions were used. The results from this analysis are as follows: 1) The most significant changes in body dimensions in advanced age were the decrease of bust height and the increase of both abdomen girth and waist girth. 2) Distinct physical changes did not appear until advanced senescence(70~79 years of age). 3) In the three somatotype groups(thin, average, and plump) categorized by their Rohrer index, the dimensions that remained unchanged in senescence were back waist length and front waist length ; the dimensions that varied most significantly in senescence were the waist measurements. 4) As a result of the analysis of coefficients of correlation among the body dimensions of the 3 figure groups categorized by the Rohrer index, the fundamental dimensions for establishing the size of ready-to-wear garments of elderly women were the stature, bust girth and center back length in upper garments. 5) The result of the analysis of physical index and proportion of the 3 figure groups showed that the more plump a figure might be, the ratio of depth to width measurements increased; the back waist height was higher and trunk enlarged. 6) The 9 figure categorized by their Rohrer index and stature showed that the percentage of women in the category of“normal figure”decreased more in advanced senescence than during early senescence. 7) An analysis of variation of the 9 figure groups, the stature and other items for a short and thin figure were the smallest, and for a tall and plump figure, the largest.

• The Korean Journal of Emergency Medical Services
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• v.22 no.1
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• pp.83-97
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• 2018

Purpose: The purpose of this study was to provide basic data for the development of personal protective equipment (PPE) for emergency medical technicians (EMTs) during chemical, biological, radiological, nuclear, and explosive situations. Methods: Body measurements were obtained for adults aged from 20 to 59 years from the data in the 6 th Size Korea national sizing survey. These data were compared to the sizes of protective clothing currently available in the market. In-depth interviews with active paramedics with experiences of wearing PPE were conducted. Results: Most of the imported protective clothing turned out to be unfit for Korean adults. This showed the urgent need for developing appropriately sized protective clothing for Korean emergency technicians. In total, 55.0% of the respondents indicated that the current protective clothing is unsafe, and 71.0% requested the clothing to have level C protective performance. Regarding the design, many people wanted hooded all-in-one type of clothing. Conclusion: Considering these requirements, most of the wearers wanted their protective clothing to be fundamentally protective of their body, be available in various sizes with adjustable parts, and easy to wear and take off. They also wanted the clothing to be secure in clear sight, while not revealing any parts of their body and not interfringe with their ability to communicate with others.

• Journal of Ocean Engineering and Technology
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• v.32 no.6
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• pp.492-501
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• 2018

The following results were obtained from a series of studies to accumulate data to reduce the coefficient of friction for press dies by performing tribological tests before and after the UNSM treatment of SM45C. The UNSM-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those for untreated materials. When loads of 5 N, 7.5 N, and 10 N were applied to the untreated material of SM45C, the coefficient of friction was approximately 0.76-0.78. With the large specimen, a value of 0.72-0.78 was maintained at a load of 50 N despite the differences in the size of the wear specimen and working load. Tribological tests of large specimens of SM45C treated with UNSM under tribological conditions of 100 N and 50 N showed that the frictional coefficient and time constant stably converged between 0.7 and 0.8. The friction coefficients of the small specimens treated with UNSM showed values between 0.78 and 0.75 under 5 N, 7.5 N, and 10 N. The friction coefficients of the SM45C treated with UNSM were comparable to each other.