• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.60-65
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• 2001

To simulate the real molding conditions, the effects of phase change and compressibility of the resin were considered in the present investigation. A modified Cross model with either an Arrhenius-type or WLF-type functional form was used for modeling viscosity of the resin. A double-domain Tait equation of state was employed to describe the compressibility of the resin during molding. The energy balance equation including latent-heat dissipation fur semi-crystalline materials was solved in order to predict the solidified layer and temperature profile. Injection molding experiments were carried out using polypropylene(PP) in the present study. Based on the comparison between experiments and simulations, it was found out the predicted pressure distributions and melt front propagations were accurate. Thus it was concluded that the program developed in this study was proved to be useful in simulations of injection molding process.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.2
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• pp.107-114
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• 2017

Results of the analysis have revealed that the students were basically divided into three groups depending on goodness-of-fit index and latent class division factor. Type 1 was regarded as a low dependence group (50.1%) with all low indexes while Type 2 was classified as a high dependence group (10.7%) with all high indexes. As for Type 3, it was titled intermediate dependence group (39.2%) for the indexes showed a low-to-moderate movement. A multinomial logistic regression analysis was carried out to forecast smart phone dependence characteristics and as a consequence, when the high dependence group was compared to the intermediate dependence group, as self-esteem and peer attachment increased and deceased respectively, a chance of one being classified into the intermediate dependence group rose. In an investigation to compare the high dependence group with the low dependence group, it was confirmed that the greater the self-esteem, the shorter the peer socializing time, the lower the neglect degree and the lower the peer attachment, a chance for one belonging to the low dependence group increased. This study also offered implications, limits and directions in follow-up research.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.603-614
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• 2020

The purpose of this study was to classify latent profiles based on SNS addictive tendencies of married women and to examine the effects of age, adult attachment, extrinsic motivation of the fear of missing out and marriage satisfaction. A total of 300 married women who have been using SNS participated in this study. The result indicated that there were three latent profiles for SNS addictive tendencies of married women : (1) high-risk group (2) potential-risk group (3) low-risk group. The high-risk group had high scores in all sub-areas (obsession and withdrawal symptoms, over-communication and immersion, over-consumption). The high-risk group accounted for 24.51% of the total and the potential-risk group was 44.33%, which had the highest proportion of them. While attachment anxiety, attachment avoidance, extrinsic motivation of the fear of missing out, and marriage satisfaction were significant determinants of latent profiles, age was not. This study divided groups according to the characteristics of married women's SNS addiction tendencies and provided implications for counseling and education according to group characteristics, and discussed the need for various research through the development of standardized SNS addiction scale for married women.

• Communications of Mathematical Education
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• v.34 no.1
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• pp.17-39
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• 2020

The purpose of this study is to analyze the mathematical beliefs of students and teachers by Latent Class Analysis(LCA). This study surveyed 60 teachers about beliefs of 'nature of mathematics', 'mathematic teaching', 'mathematical ability' and also asked 1850 students about beliefs of 'school mathematics', 'mathematic problem solving', 'mathematic learning' and 'mathematical self-concept'. Also, this study classified each student and teacher into a class that are in a similar response, analyzed the belief systems and built a profile of the classes. As a result, teachers were classified into three types of belief classes about 'nature of mathematics' and two types of belief classes about 'teaching mathematics' and 'mathematical ability' respectively. Also, students were classfied into three types of belief classes about 'self concept' and two types of classes about 'School Mathematics', 'Mathematics Problem Solving' and 'Mathematics Learning' respectively. This study classified the mathematics belief systems in which students were categorized into 9 categories and teachers into 7 categories by LCA. The belief categories analyzed through these inductive observations were found to have statistical validity. The latent class analysis(LCA) used in this study is a new way of inductively categorizing the mathematical beliefs of teachers and students. The belief analysis method(LCA) used in this study may be the basis for statistically analyzing the relationship between teachers' and students' beliefs.

• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.290-299
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• 2000

A three-dimensional model was developed in order to simulate heat and fluid flow of a continuous casting billet. The model was coded with the general-purpose CFD program FIDAP, using the finite element method. The present model consists of 2 individual calculation schemes, named model 1 and model 2. Mold region only was calculated to check the pouring stream through submerged nozzle with model 1. Entire region, which consists of mold, secondary cooling, radiation cooling was calculated to predict crater end position, temperature profile and solid shell profile(model 2). Standard $k-{\bullet}\hat{A}$ turbulence model has been applied to simulate the turbulent flow induced by submerged nozzle. Enthalpy method was adopted for the latent heat of solidification. Fluid flow in mushy zone was treated using variable viscosity approach. The more casting speed and superheat increased, the more metallurgical length increased. The shell thickness at the mold exit is proved to be mainly controlled by superheat by the present simulation. It may be concluded that the present model can be successfully applied far the prediction of heat and fluid flow behavior in the continuous casting process.

• Journal of KIISE:Software and Applications
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• v.28 no.2
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• pp.149-156
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• 2001

정보의 가치와 사용자의 정보획득 요구가 증대됨에 따라 특정 개인 위주의 서비스를 제공하는 정보검색 시스템의 필요성이 증대되고 있다. 그러나 현재의 정보검색 시스템들은 사용자의 선호도를 반영하고 편의성을 제공하는 면에서 매우 미흡한 점들이 많다. 따라서 본 논문에서는 적합성 정도에 따라 최적의 문서를 제공하기 위하여 사용자 위주의 문서순위결정 기법을 제안한다. 특정 개인의 선호도(preference)를 반영하기 위하여 사용자 프로파일(User Profile)을 구성 및 갱신하고, LSA(Latent Semantic Analysis)를 적용하여 적합율에 따라 문서의 순위를 결정한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.74-81
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• 1991

The temperature profile of Czochralski single crystal growth system was simulated considering the fluid flow and surface radiation heat transfer. View factors of surface elements were calculated for radiation heat transfer. Two phases(solid and liquid) were treated as a continuous phase by assigning artificial large viscosity to the solid phase and latent heat was accounted by iterative heat revolution method. The solidification model was applied to solid front of the pure Ga during the melting to verify the model. The whole simulation model of CZ system was applied to the growth Al single crystal.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.64-70
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• 1995

We discussed the thermal analysis for a recording media with the variation of the laser pulse duration, the laser power and the temperature distribution in order to optimize the Te-based antireflection structure from the computer calculations. In the case that the radial heat diffusion is negligible, we can calculate the maximum temperature of the recording layer at the center of the spot by the Simple Model. The temperature profile of the recording layer is obtained from the Numerical Model by considering the total specific heat and the latent heat. As a result, the effect of the heat sinking acting as a thermal loss for the hole formation could be minimized by introducing the pulse with the hole formation duration(.tau.) below the thermal time constant(.tau.$_{D}$) of a dielectric layer. These requirments can be satisfied by using the dielectric thickness of the 2nd ART(Anti-Reflection Trilayer) condition or the dielectric materials with a low thermal diffusivity.y.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.123-126
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• 1994

We discussed the thermal analysis for recording media with the variation of the laser pulse duration and the power and the temperature distribution for the optimized Te-based antireflection structure by using the computer calculations. If the radial diffusion of heat is negligible, we can calculate the maximum temperature at the spot center in recording layer by Simple Method, and the temperature profile considering the specific heat and the latent heat by Numerical Method. As a result, the effect of the heat sinking which acted as a loss for the hole formation can be minimized by introducing the pulse of the hole formation duration( $\tau$ ) shorter than the thermal time constant( $\tau$$\sub$D/) of dielectric layer. This requirments can be satisfied as using the dielectric thickness of the 7nd ART condition or the dielectric materials with low thermal diffusivity.

• Journal of Korea Multimedia Society
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• v.20 no.1
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• pp.66-73
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• 2017

Due to the recent rapid changes in society and wide spread of information devices, diverse digital information is utilized in a variety of economic and social analysis. Information related to the crime statistics by type of crime has been used as a major factor in crime. However, statistical analysis using only the structured data has the difficulty in the investigation by providing limited information to investigators and users. In this paper, structured data and unstructured data are analyzed by applying Korean Natural Language Processing (Ko-NLP) and the Latent Semantic Analysis (LSA) technique. It will provide a crime profile optimum system that can be applied to the crime profiling system or statistical analysis.