• 한국정밀공학회지
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• 제21권6호
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• pp.52-59
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• 2004

Recently the high speed end-milling processing is demanded the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. The working factors of high speed end-milling has an effect on surface roughness of cutting surface. Therefore this study was carried out to analyze the working factors to get the optimum surface roughness by design of experiment. From this study, surface roughness have an much effect according to priority on distance of cut, feed rate, revolution of spindle and depth of cut. By design of experiment, it is effectively represented shape characteristics of surface roughness in high speed end-milling. And determination($R^2$) coefficient of regression equation had a satisfactory reliability of 76.3% and regression equation of surface roughness is made by regression analysis.

• 한국수자원학회논문집
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• 제46권5호
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• pp.547-558
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• 2013

설계홍수량 산정 시 일반적으로 활용하는 합성단위도법에 대한 개선안을 제시하였다. 본 연구에서는 합성단위도의 형태를 결정짓는 첨두 비유량과 첨두시간의 결정을 위하여 첨두수문량과 유역의 지형공간적 형상계수간의 회귀분석을 시행한 결과, 유역의 단순 공간적 기하요소보다는 형상계수의 결정계수가 뚜렷이 높았으며, 유역의 지형특성영향을 독립적으로 검토할 경우 결정계수가 0.52~0.69에 그쳤으나, 지형특성이 조합된 형상계수를 이용하여 민감도분석을 해보면 결정계수가 0.73~0.81로 개선된 결과를 확인할 수 있었다. 일반적으로 단위도를 적용할 수 있는 적합한 유역의 면적은 대략 500~700 $km^2$이라 볼 때, 이러한 영역에서 유역유출모의를 통한 본 연구의 합성단위도를 검증한 결과, 특이값이 발생하는 유역을 제외하고 본 연구결과의 상대오차가 1.7~29.0%(평균 11.6%)의 수준을 보여주었다. 합성단위도법 적용에 관한 기존사례(KICT, 2000)는 상대오차가 35.0~64.9%(평균 46.7%)를 보여주어 본 연구의 제안식이 기존에 비하여 개선된 결과를 보여주고 있다.

• 소성∙가공
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• 제31권1호
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• pp.17-22
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• 2022

Hot stamping is widely used to manufacture structural parts to satisfy requirements of eco-friendly vehicles. Recently, hot forming technology using uncoated steel sheet is being studied to reduce cost and solve patent problems. In particular, research is focused on process technology capable of suppressing the generation of an oxide layer. To evaluate the oxide layer in the hot stamping process, Gleeble testing machine can be used to evaluate the oxide layer by controlling the temperature history and the atmosphere condition. At this time, since cooling by gas injection is impossible to protect the oxide layer on the surface of a specimen, research on a method for securing a quenching speed through natural cooling is required. This paper proposes a specimen shape design method to secure a target quenching speed through natural cooling when evaluating the oxide layer of an un-coated boron steel sheet by Gleeble test. For the evaluation of the oxide layer of the un-coated steel sheet through the Gleeble test, dog-bone and rectangular type specimens were used. In consideration of the hot stamping process, the temperature control conditions for the Gleeble test were set and the quenching speed according to the specimen shape design was measured. Finally, the quenching speed sensitivity according to shape parameter was analyzed through regression analysis. A quenching speed prediction equation was then constructed according to the shape of the specimen. The constructed quenching speed prediction equation can be used as a specimen design guideline to secure a target quenching speed when evaluating the oxide layer of an un-coated boron steel sheet by the Gleeble test.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.163-168
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• 2013

A construction workspace is considered as a critical factor to secure constructability and safety of a project. Specially, optimized size of each workspace helps to minimize any conflicts between workspaces, works and resources within a workspace in the construction site. However, since an existing method for making a decision workspace's size depends on generally experiences of managers and work conditions of activity, it is difficult to perform safe works considering feasible workspace size. The workspace size is changed according to the quantity of resources allocated into each activity as time progresses. Accordingly, it is desirable that optimized workspace size considering input size of resources is determined. To solve these issues, this study configures an optimized model for deciding standard size of workspaces by simple regression analysis and develops a visualized scenario model for simulating the optimized workspace shape in order to support BIM (Building Information Modeling) environment. For this, this study determines an optimized resource shape size considering maximum working radius of each resource and constructs its visual model. Subsequently, input size of resources for each activity is estimated considering safety execution area of resources and workspaces. Based on this, an optimized 3D workspace shape is generated as a VR simulation model of a BIM system based on the suggested methodologies. Moreover, operational feasibility of the developed system is evaluated through a case study for a bride project. Therefore, this study provides a visualized framework so that project managers can establish an efficient workspace planning in BIM environment. Besides, it is expected that constructability, productivity and safety of the project will be improved by minimizing conflicts between workspace and congestions between resources within a workspace in the construction phase.

• 복식문화연구
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• 제32권3호
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• pp.364-380
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• 2024

This study aimed to identify changes in upper body measurements and body shape types among women over a 10-year period based on data from the 6th and 8th Size Korea Anthropometric Surveys. The study used regression analysis to explore the relationship between various dimensions, enabling the prediction of different upper body dimensions based on height and waist circumference. The sample consisted of 1,179 women in their 20s who participated in the 6th (2010) and 8th (2020) Size Korea Anthropometric Surveys, with 33 items analyzed. Initially, most items, except those related to height, exhibited larger values in the 8th Survey than in the 6th, suggesting a general increase in the upper body dimensions of females in their 20s over the 10-year period. Subsequent factor analysis revealed three factors crucial for determining the upper body shape of women in this age group. The body shapes were then categorized into four distinct clusters. Regression analysis indicated that both waist circumference and height significantly influence most of the measured items, with waist circumference having a more substantial impact in most models. Through this research, we aim to provide foundational data that reflects the evolving upper body shapes of women in their 20s to enhance clothing production and improve the sizing system.

• 한국생활과학회지
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• 제21권6호
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• pp.1223-1234
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• 2012

The purpose of this study was to investigate the effects of body weight, perception of body shape and satisfaction with body shape on obesity stress and self-esteem among middle school students. The participants in this study were 446 middle school students in K-city. The major results of this study are as follows. First, male students demonstrated higher obesity rates than female students, and female students considered themselves to be fatter and less satisfied with their body shape than male students. Female students had significantly more obesity-related stress than male students. Second, there were significant differences in physical obesity stress according to body weight status among male and female students, and there was statistically significant difference in psychological obesity stress according to body weight status among male students. Male and female students who considered themselves to be fatter and less satisfied with their body shape suffered from high obesity stress. Third, there was no significant difference in self-esteem according to body weight status, but self-esteem was affected by perception and satisfaction of body shape; male and female students who considered themselves to be fatter and less satisfied with their body shape showed low levels of self-esteem. As the result of regression analysis, psychological obesity stress was the strongest factor in explaining self-esteem among all students, and satisfaction of body shape was also found to be a significant variable among female students.

• 한국농공학회논문집
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• 제61권4호
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• pp.33-42
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• 2019

In this study, the channel and floodplain widths are indirectly measured for three different watersheds using satellite images to reflect the shape of Korean channels in the Soil and Water Assessment Tool (SWAT) model. For measuring the channel and floodplain widths, multiple satellite images were referred to ensure the widest width of certain points. In the single channel, the widths at the multiple points were measured. Based on the measured data, the regression equations were derived to estimate the channel and floodplain widths according to watershed areas. Applying these developed equations, this study evaluated the effect of the change of channel and floodplain widths on the SWAT simulation by comparing to the measured streamflow data. The developed equations estimated larger channel width and smaller floodplain compared with those calculated in the current SWAT model. As shown in the results, there was no considerable changes in the predicted streamflow using the current and developed equations. However, the flow velocity and channel depth calculated from the developed equations were smaller than those of the current equations. The differences were caused by the effect of different channel geometries used for calculating the hydraulic characteristics. The channel geometries also affected the water quality simulation in channels because the hydraulic characteristics calculated by the channel geometries are directly related to the water quality simulation. Therefore, application of the river cross-sectional regression equation reflecting the domestic stream shape is necessary for accurate water quantity / quality and water ecosystem simulation using hydrological model.

• 한국의류산업학회지
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• 제19권6호
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• pp.749-758
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• 2017

The purpose of the present study is to develop a grading deviation, which is appropriate for the body type of women in thirties, by analyzing the three-dimensional body type. The materials for the study were adopted from the body measurement data of women in the age group of 30 to 39 years old, provided from Size Korea. By reflecting the factor analysis results using the three-dimensional shape measurement, deviations were derived. First, six factors influencing the changes in human body shape were derived as waist-hip length factor, bust-waist shape factor, back protrusion back shoulder factor, bust length factor, shoulder length factor, and frontal waist dart factor. The bust size and height, which can be easily utilized for the top original grading, were used for deriving a regression formula, and the deviation was set in accordance with the result. Second, by applying the deviation which reflects the changes in the body shape, the crimps which were generated due to the application of existing deviation were remarkably reduced, indicating that the grading of the present study is more fitting than the existing one. The deviation derived by the analysis of actual increase and decrease of body size was more fitting than the existing one. This was proved by actual wearing experiment, which represents the significance of this study.

• International Journal of Korean Welding Society
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• 제1권2호
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• pp.36-44
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• 2001

To get the appropriate welding process variables, mathematical modeling in conjunction with many experiments is necessary to predict the magnitude of weld bead shape. Even though the experimental results are reliable, it has a difficulty in accurately predicting welding process variables for the desired weld bead shape because of nonlinear and complex characteristics of welding processes. The welding condition determined for the desired weld bead shape may cause the weld defect if the welding current/voltage/speed combination is improperly selected. In this study, the $2^{n-1}$ fractional factorial design method and correlation parameter were used to investigate the effect of the welding process variables on the fillet joint shape, and the multiple non-linear regression analysis was used for modeling the gas metal arc welding(GMAW）parameters of the fillet joint. Finally, a fuzzy rule-based method and a neural network method were proposed so that the complexity and non-linearity of arc welding phenomena could be effectively overcome. The performance of the proposed neuro-fuzzy system was evaluated through various experiments. The experimental results showed that the proposed neuro-fuzzy system could effectively check the welding conditions as to whether or not weld defects would occur, and also adjust the welding conditions to avoid these weld defects.

• 기본간호학회지
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• 제21권4호
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• pp.362-369
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• 2014

Purpose: The purpose of the study was to investigate factors that influence university women with eating problems. Methods: Study participants were 307 women from two universities. Self-report questionnaires which included items on eating problems, satisfaction with body shape, self-esteem, body mass index, and weight control methods were used. Data were analyzed using independent t-tests, ${\chi}^2$ tests, and a multiple binary logistic regression. Results: About 20% of the undergraduate women were experiencing eating problems. The problematic eating group showed more dissatisfaction with body shape than the normal eating group, and used more diets, fasting, diet-products, and uretics/laxatives to control body weight. Significant predictors for the problematic eating group were diets, diet-products, BMI, self-esteem and dissatisfaction with body shape. The strongest predictors were diets; risk for women university students who had been on a diet was 15 times higher than their counterparts. Conclusion: It is pertinent for health professionals to start intervention programs to educate university women with eating problems. The contents should include information on healthy weight control methods, improving satisfaction with body shape and self esteem, as well as creating social atmosphere about healthy body shape for women.