• Journal of the Korean Data and Information Science Society
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• 제26권1호
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• pp.123-139
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• 2015

이 연구의 목적은 통계청에서 실시한 2011년도 사교육비 조사의 자료를 이용하여 학생의 학업성취도, 가정의 사회경제적 지위, 보완 사교육비, 일반 사교육비 사이의 효과를 구조방정식 모형을 이용하여 분석하고, 이러한 구조적 효과가 성, 지역, 학교급 집단 별로 유의한 차이가 있는지 다중집단 구조방정식을 활용하여 확인하는 것이다. 연구 모형의 분석 결과를 바탕으로, 사회경제적 지위가 높을수록 사교육에 대한 지출이 커지는 경향이 있지만 학업성취도에는 영향을 미치지 않는다는 결론을 얻을 수 있다. 또한 성, 지역, 학교 집단 모두 학생의 학업성취도, 부모의 사회경제적 지위, 사교육비의 집단 간 구조적 효과의 차이가 있다는 결론을 얻을 수 있다. 이 연구를 통해 우리나라 교육 현상 중에서 학업에 대한 열의가 사교육으로 많이 집중되어 나타나는 사교육 문제에 있어 학생의 학업성취도, 부모의 사회경제적 지위와 사교육비가 연관되어 있을 것이라는 사회적 통념을 2011년 사교육비 조사자료를 이용하여 판단할 수 있을 것이라고 기대한다.

• 품질경영학회지
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• 제31권1호
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• pp.21-41
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• 2003

The purpose of this research is to identify if psychological temptation, site quality and sense of community influence user's flow and addiction and if causalities among flow, addiction, customer satisfaction and customer loyalty are different between Korean and Japanese online games. To perform our research, we use MCSF(Multi-group Confirmatory Factor Analysis) and MSEM(Multi-group Structural Equation Model). The empirical results of SEM(Structural Equation Model) including high-order factor analysis indicate that all of paths in our model are the same for both countries. Therefore, site quality and sense of community have impacts on the flow, while on the other hand, psychological temptation has impacts on the addiction. Customer satisfaction and loyalty are positively related not with the addiction but with the flow. In addition, customer loyalty is significantly influenced by the flow and the customer satisfaction. In Conclusion, the empirical results of MSEM(Multi-group Structural Equation Model) indicate sense of community to flow, flow to loyalty and customer satisfaction to loyalty are different between Korea and Japan. This indicates that companies to penetrate into Japa online game industry should have a concern with Japanese Social and Cultural features and to develop strategies which correspond with Japanese culture.

• Structural Engineering and Mechanics
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• 제43권1호
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• pp.71-87
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• 2012

This paper extends a single equation, semi-analytical approach for three-span bridges to multi-span ones for the rapid and precise determination of natural frequencies and natural mode shapes of an orthotropic, multi-span plate. This method can be used to study the dynamic interaction between bridges and vehicles. It is based on the modal superposition method taking into account intermodal coupling to determine natural frequencies and mode shapes of a bridge deck. In this paper, a four- and a five-span orthotropic roadway bridge deck are compared in the first 10 modes with a finite element method analysis using ANSYS software. This simplified implementation matches numerical modeling within 2% in all cases. This paper verifies that applicability of a single formula approach as a simpler alternative to finite element modeling.

• 대한치과보철학회지
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• 제38권5호
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• pp.575-582
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• 2000

This investigation was designed to determine whether heat-pressing and/or simulated heat treatments affected the flexure strength and the microstructure of the lithium disilicate glass-ceramic in the IPS Empress 2 system. Four groups of the specimens were prepared as follows: group 1 - as-received material, group 2 - heat-pressed material; group 3 - heat-pressed and simulated initial heat-treated material; group 4 - heat-pressed and the simulated heat-treated material with full firings for a final restoration. The three-point bending test and the scanning elec-tron microscope (SEM) analysis was conducted for the purpose of this study. The flexure strength of group 2 was significantly higher than that of group 1. However, there were no significant differences in strength among group 2, 3, and 4, and between group 1 and 4. The SEM micrographs of the lithium disilicate glass-ceramic showed the closely packed, multi-directionally interlocking microstructure of numerous lithium disilicate crystals protruding from the glass matrix. The crystals of the heat-pressed materials (group 2, 3, and 4) were a little denser and about two times bigger than those of the as-received material (group 1). This change of microstructure is more obviously exhibited particularly between group 1 and 2. However, there was no a marked difference among group 2, 3, and 4 after the heat-pressing procedure. Although there were significant increase of the strength and some changes of the microstructure after the heat-pressing operation, the combination of the heat-pressing and the simulated subsequent heat treatments did not produce the increase of strength of IPS Empress 2 glass-ceramic.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.893-904
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• 2020

The study examines the relationship between credit risk and operational risk (understanding of risk management, risk identification, risk assessment and control, and risk monitoring) on risk management practices followed by private and public sector commercial banks. The cross-sectional data method was used to check the impact of risk management practices. Data was collected from the bank employees and a total of 284 respondents were finally selected for further analysis. Measurement Invariance of Composite Models analysis is used to test the quality of the measurement model for sub-samples, and multi-group analysis is used for path analysis in sub-sample through PLS-SEM. The findings of the study as the total sample show that both types of banks are managing adequate and significant risk management practices. On the other hand, sub-groups' results show private sector banks are more momentous than public sector banks. Risk identification is significantly different at the sub-group level, which shows public sector banks are more concentrating on this type of risk. Understanding of risk management has no significant effect on both types of banks and risk assessment & control for public sector banks, and there is a difference in the risk management practices among private and public sector commercial banks.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.732-743
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• 1995

The purpose of this study was to evaluate the adaptation of light cured dentin bonding agents to tooth structure by measuring contraction gaps on interfaces between cavity wall and composite resin under SEM study. In this study, class V cavities with cementum margin were prepared on the buccal surfaces of 15 extracted human premolar teeth and teeth were randomly assigned 3 groups of 5 teeth each. The cavities were filled with three dentin bonding agents and two composite resins were investigated for this study: three dentin bonding agents; Scotchbond 2, Scotchbond Multi-Purpose. All-Bond 2, two composite resins; Silux Pius, Z-100. Group 1 : Scotchbond 2 + Silux Plus Group 2 : Scotchbond Multi~Purpose + Z-100 Group 3 : All-Bond 2 + Z-100 The restored teeth were stored in 100% relative humidity at $37^{\circ}C$ for 7 days. And then, the roots of the teeth were removed with the tapered fissure bur and the remaining crowns were sectioned occlusogingivally through the center of restorations. Adaptation at tooth-restoration interface was assesed occlusally, gingivally, and axially by scanning electron microscope. The results were as follows : 1. In Group 1, the adaptation to dentinal wall of Scotchbond 2 was poor, but the adaptation to enamel wall of Scotchbond 2 was excellent. 2. In Group 2, the adaptation to occlusal was axial wall and gingival wall of Scotchbond Multi-Purpose was excellent. Especially in axially wall, the dentin bonding agents infiltrated into dentinal tubules and there was excellent adaptation to dentinal wall. 3. In Group 3, the adaptation to occlusal wall and axial wall of All-Bond 2 was excellent. But in gingival wall, there was gap formation between composite resin and dentin bonding agent.

• KIEE International Transactions on Electrophysics and Applications
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• 제2C권6호
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• pp.309-313
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• 2002

In this paper, we have studied minimization of the kerf-width and surface burning, which occurred after the conventional singulation process of the multi-layer BGA board with copper, polyethylene and epoxy glass fiber. The high thermal energy of a pulsed Nd:YAG laser is used to cut the multi-layer board. The most considerable matter in the laser cutting of the multi-layer BGA boards is their different absorption coefficient to the laser beam and their different heat conductivity. The cut mechanism of a multi-layer BGA board using a 2$^{nd}$ harmonic Nd:YAG laser is the thermal vaporization by high temperature rise based on the Gaussian profile and copper melting point. In this experiment, we found that the sacrifice layer and Na blowing are effective in minimizing the surface burning by the reaction between oxygen in the air and the laser beam. In addition, N2 blowing reduces laser energy loss by debris and suppresses surface oxidation. Also, the beam incidence on the epoxy layer compared to polyimide was much more suitable to reduce damage to polyimide with copper wire for the multi layer BGA singulation. When the polyester double-sided tape is used as a sacrifice layer, surface carbonization becomes less. The SEM, non-contact 3D inspector and high-resolution microscope are used to measure cut line-width and surface morphology.

• 한국세라믹학회지
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• 제45권10호
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• pp.610-617
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• 2008

Multi-walled carbon nanotube(CNT) reinforced hydroxyapatite composite coating with a thickness of $5{\mu}m$ has been successfully deposited on Ti substrate using aerosol deposition(AD). The coating had a dense microstructure with no cracks or pores, showing good adhesion with the Ti substrate. Microstructural observation using field-emission scanning electron microscopy(FE-SEM) and transmission electron microscopy(TEM) showed that CNTs with original tubular morphology were found in the hydroxyapatite-CNT(HA-CNT) composite coating. Measurements of hardness and elastic modulus for the coating were performed by nanoindentation tests, indicating that the mechanical properties of the coating were remarkably improved by the addition of CNT to HA coating. Therefore, HA-CNT composite coating produced by AD is expected to be potentially applied to the coating for high load bearing implants.

• Structural Engineering and Mechanics
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• 제47권2호
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• pp.265-286
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• 2013

A study on economic performances of consecutive multi-span suspension bridges is carried out. In this part of the study, material amount and structural cost estimation formulas of the bridges is derived based on the structural ultimate carrying capacity. The bridge cost includes the part of superstructure and the part of substructure. Three types of bridge foundations, bored piles, concrete caissons and floating foundations, are considered in substructure. These formulas are to be used for the parametric study of the bridge cost in order to define its more economical layout under different conditions in the part two of the study.

• 사회복지연구
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• 제41권2호
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• pp.67-99
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• 2010

우울과 자살 간에 유의한 관계가 있다는 기존의 연구에도 불구하고, 통계자료는 우울 유병률은 여성이 높으나 자살률은 남성이 높다는 것을 보여준다. 본 연구의 목적은 우울과 자살태도의 관계에 대한 탐색적 고찰을 통하여 이러한 성별차이에 대한 경험적 이해를 도모하고, 향후 우울 및 자살에 대한 성별 및 연령별 차이의 연구에 대한 방향성과 함의를 제공하는 것을 주목적으로 한다. 이러한 목적을 달성하기위하여 서울복지패널 1차년도 자료를 사용하여, 18세 이상 성인 7,396명을 대상으로 우울과 자살태도와의 관계, 우울과 자살태도 간의 관계에 있어서의 성별 및 연령 차이에 대해서 구조방정식 및 다중집단분석을 통해서 분석하였다. 기존 연구결과와 동일하게 전체적으로 우울과 자살태도의 관계는 유의하게 나타났다. 다중집단분석결과는 우울과 자살태도의 관계가 여성집단보다 남성집단에서 강하게 나타나는 것을 보여주었고, 이러한 성별차이는 65세 이상의 여성집단에서 우울과 자살태도의 관계가 다른 세 집단에 비해서 상대적으로 약하기 때문인 것으로 나타났다. 이러한 결과는 우울 유병율은 여성이 높은데 자살률은 남성이 높은 이유 중의 하나는 우울이 자살에 영향을 주는 정도가 남성집단에서 여성집단보다 강하기 때문이라는 것을 보여주고, 우울과 자살간의 관계의 성별차이의 주 원인은 65세 이상 여성의 특성이 상당부분 기여하고 있는 것을 보여준다. 결과를 바탕으로 이론적 실천적 함의를 논의하였다.