• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.100.3-100
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• 2001

This article deals with the development of a mathematical model for the finishing polycarbonate polymerization process using a horizontal rotating disk-ring reactor with counter-current gas sweeping and the performance analysis of the reactor system by using the model. Here we intend to propose a model describing the reactor system consisting of two phases, in which by-product phenol is removed from the polymer of high molecular weight compatible with the products of commercial grades. The vapor phase is represented by a tanks-ln-series model while the polymer melt phase is regarded as a plug flow reactor.

• 한국도로학회논문집
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• 제14권5호
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• pp.47-55
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• 2012

PURPOSES: SUPERPAVE binder grade tests including Multiple Stress Creep and Recovery(MSCR) test are applied to evaluate rheological properties of four polymer modified binders. METHODS: To evaluate grade of four modified binders, PG testing protocols, such as DSR, BBR and MSCR are employed. RESULTS: It is observed that MSCR test shows different performance grades especially on modified binders. Both DMP and EG binder show similar high temperature performance to SBS 5% modified binder. CONCLUSIONS: Binder Grading system in Korea need to be reviewed to properly reflect the performnace of modified binders. The binders modified with DMP and EG can be possible alternatives SBS 5% modified binder considering its performance and cost.

• 한국학교ㆍ지역보건교육학회지
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• 제17권3호
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• pp.49-59
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• 2016

Objectives: This study was conducted to investigate the relationship between self-esteem and stress among adolescents. Methods: The subjects of this study were 1,025 from elementary, middle and high school students in Dangjin city. Data were measured using self-esteem scale and brief encounter psychosocial instrument. The data were analyzed frequencies, t-test, ANOVA, Pearson's correlation coefficient and multiple linear regression analysis using the SPSS 12.0 program. Results: Self-esteem was correlated with stress negatively among adolescents. In multiple linear regression analysis, self-esteem had a statistically significant negative effect on stress. Affecting factors of the self-esteem in all schools were grades, economic status and relationship with parents. Conclusion: The results of this study help to provide a basis for the development of a self-esteem management program to alleviate the stress for adolescents. The program of human relationship should be developed and provided to improve the self-esteem.

• Journal of the Korean Wood Science and Technology
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• 제26권2호
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• pp.16-23
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• 1998

This paper examines the effects of specimen length and grade on the strength and stiffness properties of structural timber of radiata pine. The tensile strength and modulus of elasticity of 1,902 machine-graded boards with 3.15- and 1.62-m clear span lengths, were determined using a horizontal tension test machine. The mean failure and characteristic stress values for tensile strength show an extremely high dependency on test specimen length. The mean and characteristic values of both modulus of elasticity and tensile strength show significant dependency on machine stress grades.

• 한국주거학회논문집
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• 제14권5호
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• pp.95-104
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• 2003

The purpose of this research is to find out environmental characteristics of elementary school children's room, and determine the relationship between children's room environment and their emotional characteristics. For the research, used were a developed measurement instrument for environmental characteristics of children's room as well as the emotion measurement instrument published by Korean Testing Co. and developed by Dr. Lee Jong-seung for elementary school children in their higher year grades. The results showed that environmental characteristics of children's room has relationship with children's emotional characteristics. The order of environmental characteristics had a direct and high relationship with children's emotional characteristics, while originality had indirect relationship with children's emotional characteristics through intervening variables. The human relationship of children's emotional characteristics was the most influenced by children's room environmental characteristics.

• 보건교육건강증진학회지
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• 제30권2호
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• pp.11-21
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• 2013

Objectives: The objective of this paper is to study influence of self esteem, family support and adaptation to school life on adolscents' suicidal ideation adjsuted for general characteristics effect. Methods: Using cluster sampling, 318 high school freshmen from T city were extracted as survey subjects. Independent t-test, ANOVA, Duncan test, Pearson's correlation coefficients and multiple regression analysis were applied for statistical analysis. Results: Among general characteristics, religion, family income, single-parentedness, health status and school grades were statistically significant with suicidal ideation. Controlling the above variables, increase in self-esteem (${\beta}$=-.300) and family support (${\beta}$=-.267) showed statistically significant decrease in suicidal ideation but adaptation to school life did not. Conclusions: Therefore, it is proposed that measures for enhancement of self esteem and family support to be included in development of suicide prevention programs.

• 대한가정학회지
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• 제42권12호
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• pp.69-76
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• 2004

The purpose of this study was to investigate the colorfastness of cotton and silk fabric dyed with extract of Lotus leaf princeps. The experimental items were classified into mordanting treatments, fabric components and kind of mordants. The experimental test was done by laundering, abrasion(dry/wet), perspiration(acid/alkali) , light fastness, color difference by C.C.M(computer color matching) system and K/S test. The summarized findings resulting from the experiment and investigation are as follows: In the C.C.M and K/S test on mordanting method and kind of fabrics, co-mordanting treatment method and protein fabric (silk) were the most effective. Especially, Fe mordanting treatment was higher than Al, Cu, Cr and none-mordanting. In colorfastness on the mordants, perspiration and laundering fastness showed high grade (4-5) but grades of perspiration(2-3/4) and light fastness(1-3) were low.

• Journal of Mechanical Science and Technology
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• 제16권4호
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• pp.501-511
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• 2002

This paper presents a study of the effect of rolling temperature, roll gap (pass height), initial specimen size and steel grades of specimens on the roll force in round-oval-round pass sequence by applying approximate method and verifications through single stand pilot rod rolling tests. The results show that the predicted roll forces are in good agreement with the experimentally measured ones. The approximate model is independent of the change of roll gap, specimen size and temperature. Thus, the generality of the prediction methodology employed in the approximate model is proven. This study also demonstrates that Shida's constitutive equation employed in the approximate model needs to be corrected somehow to be applicable for the medium and high carbon steels in a lower temperature interval (700∼900$\^{C}$).

• 한국주조공학회지
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• 제20권6호
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• pp.407-418
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• 2000

The effect of various factors on the results of degassing of AC4C aluminum alloy melt by using rotary degasser were investigated. The difference between the effects of nitrogen gases of commercial pure and high purity grades on the degassing results was not significant. The optimum degassing condition was obtained. The effect of holding and degassing temperature was not significant, either. The result of degassing was deteriorated by the modification treatment of eutectic silicon, meanwhile improved by the grain refining. The effect of the latter was stronger than that of the former when the melt was treated simultaneously. The volume fractions of hydrogen porosity of the castings obtained from the molds with water moisture such as natural and green sand molds were much higher than those from the molds without that such as pep-set and $CO_2$ molds.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.126-129
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• 2005

Microstructures and tensile properties of low carbon steels, 5083 Al alloy and Ti-6Al-4V alloy fabricated by equal channel angular pressing (ECAP) were examined in order to understand their deformation response associated with a formation of an ultrafine grained (UFG) structure. Room temperature tensile properties of UFG low carbon ferrite/pearlite steels and UFG ferrite/martensite dual phase steel were compared for exploring a feasibility enhancing the strain hardening capability of UFG materials. In addition, low temperature and high strain rate superplasticity of the two grades of the UFG 5083 Al alloy, and Ti-6Al-4V alloy were presented. From the analysis of a series of experiments, it was found that UFG materials exhibited the enhanced mechanical properties compared to coarse grained counterparts.