• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.719-727
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• 1998

This study was carried out to assess the relationship between jobstrain, psychosocial distress and homocysteine. The study design was cross-sectional, and included 152 industrial workers in middle sized city. A self-adminstered questionnaire measured general characteristic, job strain and psychosocial distress. Blood was drawn into EDTA tube, and total plasma homocysteine was measured by HPLC. Homocysteine in the high job demand group was sagnificantly higher than that in the low job demand. Cholesterol in the high job control group was significantly higher than that in the low job control. Homocysteine was significantly higher in the high job strain group than that in the other group. Folate and vitamin B12 showed a significantly negative correlation with homocysteine. Multiple regression analysis was used to determine whether the psychosocial distress and other variable contributed to explaining the homocysteine. Stress correlates with the homocysteine.

• 대한예방의학회:학술대회논문집
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• 2002.10a
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• pp.266-268
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• 2002

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.7
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• pp.905-914
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• 2001

A large eddy simulation(LES) is performed for turbulent flow around a bluff body inside a sudden expansion cylinder chamber, a configuration which resembles a premixed gas turbine combustor. To promote turbulent mixing and to accommodate flame stability, a flame holder is installed inside the combustion chamber. The Smagorinsky model is employed and the calculated Reynolds number is 5,000 based on the bulk velocity and the diameter of the inlet pipe. The simulation code is constructed by using a general coordinate system based on the physical contravariant velocity components. The predicted turbulent statistics are evaluated by comparing them with the laser-doppler velocimetry (LDV) measurement data. The agreement of LES with the experimental data is shown to be satisfactory. Emphasis is placed on the time-dependent evolutions of turbulent vortical structure behind the flame holder. The numerical flow visualizations depict the behavior of large-scale vortices. The turbulent mixing process behind the flame holder is analyzed by visualizing the sectional views of vortical structure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.06a
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• pp.174-182
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• 1997

The technology of Semi-Solid Forging (SSF) has been actively developed to fabricate near-net-shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating, forming, compression -holding and ejecting step. After forming step in SSF, the slug is compressed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. The compression holding time that can affect microstructural characteristics and shape of products is important to make decision, where it is necessary to find overall heat transfer coefficient properly which has large effect on heat transfer between slug and die. This paper presents the procedure to predict compression holding time of obtaining the final shaped part with information of temperature and solid fraction for a cylindrical slug at compression holding step in closed-die compression process using heat transfer analysis considering latent heat by means of finite element method. The influence of the predicted compression holding time on microstructural characteristics of products is finally investigated by experiment.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.155-164
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• 2017

PURPOSES : Owing to the growth of income and socio-economic levels, demands from road users have diversified. Accordingly, new road policies are being actively sought. The metropolitan city government of Busan has been focused on constructing and expanding roads to accommodate the increasing traffic demand. Given the increase in functional characteristics, we need to re-evaluate the hierarchy and function of roads, and specifically remodel the road planning and operations that fit into their functions. METHODS : First, this study focuses on introducing the minimum condition required to redefine the hierarchy of the roads. Second, the authors propose a new model that identifies the impact level of road hierarchy adopting discriminated analysis technique. RESULTS : Authors suggest that we redefine the hierarchy of roads in the central business distinct in Busan, and specifically the arterial roads in Busan, namely, Joonang-daero and Gaya-ro. These roads need to be reequipped with cross walks, a lower speed limit, and exclusive bus lanes to improve their accessibility. CONCLUSIONS : The authors found that the sub-arterial and collector roads have been subjected to excessive loads, owing to inappropriate functions being assigned to the main arterial road. Moreover, given that through traffic is concentrated on the sub-arterial and collector roads, over-speeding and other safety issues are consequently created.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.217-218
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• 2015

주석은 최근 첨단 전기, 전자 제품의 핵심 소재로써 지속적인 수요 증가가 예상되는 전략 금속이다. 국내의 수요량은 2011년 기준 약 17,000톤 으로 99% 이상 수입에 의존하고 있는 실정이다. 그러나, 국내의 주석 제련 산업은 전무한 상태이며 폐자원에서 재활용하는 회수 기술도 초보 단계이다. 이러한 폐자원 발생량은 12,000톤/year이며, 약 1200억원에 달하는 규모이다. 다양한 폐자원의 선별적 전처리 요소 기술 개발 및 회수 공정 시스템 개발이 절실히 요구된다. 본 연구에서는, 주석 폐자원 중 solder 용융물 및 공정 스크랩 Lead solder, Lead-free solder 등 뿐만 아니라, ITO target 제조 시 발생하는 ITO sludge 등의 고상 폐자원으로부터 페자원의 물성을 파악하여 금속/산화물과의 파/분쇄 및 분급공정을 통하여 고품위의 주석 금속을 회수하였다. 뿐만 아니라, 고순도 주석시 발생하는 양극 슬라임 침출액 등의 액상 폐자원으로부터 희소금속의 추출 및 회수를 위해 습식 전처리 공정을 수행하였다. 침출액은 주석, 구리, 납 등의 유가금속이 이온형태로 존재하고 있으며, Chlorine이 다량 함유되어 있다. 고품위의 주석 산화물을 회수하기 위하여 침출액 내의 구리 제거 공정, Chlorine 제거 공정 등을 순차적으로 수행하여 고품위의 산화물 회수를 수행하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.11a
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• pp.92-92
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• 1998

반도체 기술의 경이적인 발전에 힘입이 최근 휴대용 이동통신기기, 노트북 컴퓨터 등 무선전자제품의 폭발적인 수요와 함께 이들의 소형화, 경량화가 요구되어 전원인 2차전지의 경량화, 고용량화, 장수명화의 필요성이 절실해졌다. Ni-MH 전지는 Ni-Cd전지에 비해 에너지밀도가 1.5~2배에 이르고 충방전 cycle이 길며 오염물질이 없어 환경 친화적이라는 장점이 었다. Ni-MH 전지의 성능은 음극재료인 수소저장합금에 의해 좌우되므로 수소저장능력이 크고 내식 성이 우수한 합금개발이 중요하다. $CaNi_5$는 수소저장능력이 크고 매장량이 많아 값이 싸다는 장점이 있지만 KOH 용액에서 내구성이 떨어진다는 단점이 있어 주로 Heat Pump 재료에만 사용이 제한되어왔다. 본 실험에서는 결정 구조의 nanocrystalline 및 amorphous화함으로써 해리압의 변화, 방전용량의 변화 등 새로운 전극 특성을 나타낸다고 보고되고 있는 MG (Mechanical Grinding)방법을 통해 CaNis 합금의 전극특성의 변화를 살펴보았고, 아울러 고상-기상반응에서 표면에 형성된 산화피막을 제거하여 안정한 불화물을 표면에 형성시킴으로써 불순물 가스에 대한 내구성을 높이고 활성화특성을 향상 시킨다고 보고되고있는 불화처리 방법을 이용하여 불화처리 시간을 달리하면서 용액 속에서의 pH의 변화, ICP분석, 전극의 성능 및 표면 특성변화를 충방전 test, SEM 등을 통해 고찰하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.609-615
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• 2021

Three-dimensional numerical study was carried out to evaluate the aerodynamic characteristics of the supersonic grid fins installed on SpaceX Falcon 9. The present three-dimensional flow results were compared to the results by the concept of the unit grid fin previously introduced for more efficient and simpler flow calculations, and the validity of the approach of the unit grid fin were evaluated. The aerodynamic characteristics in supersonic flights Mach 2.8 of SpaceX Falcon 9 with various angle of attacks were also obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.456-467
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• 2018

Appearance has become an important means of expressing oneself in modern society, and women often desire to lose weight. Therefore, this study examined the diets of female college students with high weight loss needs and analyzed the effects of their body image, sociocultural attitude, body stress and diet behavior on intake weight loss products. Data were collected from 220 Korean female college students from June to July using an online survey program. The questionnaires included body image scale, Sociocultural Attitude Towards Appearance Questionnaire (SATAQ), Body Attitudes Questionnaire (BAQ) and diet behaviors scale. Data were analyzed by descriptive statistics, the $x^2$-test, Pearson's correlation coefficients, and logistic regression analysis using the SPSS 22.0 program. There were significant differences in body image, SATAQ, obesity stress and diet behavior between groups. All variables were significantly correlated with each other. Factors influencing weight loss products intake by female university students were SATAQ (OR=1.15, CI=1.03-1.29), obesity stress (OR=1.13, CI=1.06-1.20), diet behaviors (OR=1.21, CI=1.10-1.33), and knowledge regarding the side effects of weight loss products (OR=3.86, CI=1.62-9.20). Thus, it is necessary to teach female college students to recognize healthy weight control methods. Moreover, if weight loss products are needed, appropriate information should be provided regarding the ingredients and side effects of the product.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.178-185
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• 2018

The low birth rate in South Korea is a very serious problem. Recently, as personal happiness has emerged as an important life value of life, unmarried people have developed a negative tendency toward marriage. This study was conducted to investigate the attitude toward marriage, gender role and having children among college students, and to identify the factors affecting marriage. The participants were 383 unmarried nursing college students who live in D city. Data were collected from self-report questionnaires and analyzed using the t-test, one-way ANOVA, Pearson's correlation coefficients, and stepwise multiple regression using the SPSS 22.0 program. Gender was a significant variable influencing attitude toward marriage. Moreover, the attitude toward marriage was negatively correlated with gender role, and positively correlated with having children. Attitude toward gender role was negatively correlated with having children. Regression analysis of the factors affecting attitude toward marriage showed that gender (male), attitude toward gender role, and attitude toward having children were significant influencing factors. Moreover, this model explained 51.9% of variance in attitude toward marriage. Overall, it is necessary to change individual values to solve the problem of low birthrate.