• Polymer(Korea)
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• v.38 no.6
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• pp.782-786
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• 2014

Various kinds of thermal conductive ceramic/polymer composites (aluminum nitride, aluminum oxide, boron nitride, and silicon carbide/epoxy) were prepared by a casting method and their optical images were observed by FE-SEM. Among these, SiC/epoxy composite shows inhomogeneous dispersion features of SiC and air voids in the epoxy matrix layer, resulting in undesirable thermal conductive properties. To enhance the thermal conductivities of SiC/epoxy composites, the epoxy wetting method which can directly infiltrate the epoxy droplet onto filtrated SiC cake was employed to fabricate the homogeneously dispersed SiC/epoxy composite for ideal thermal conductive behavior, with maximum thermal conductivity of 3.85W/mK at 70 wt% of SiC filler contents.

• The Korean Journal of Malacology
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• v.25 no.3
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• pp.203-210
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• 2009

Optical properties and color analysis of nacreous layers were performed using various pearl shells. The cross section and microstructure of the surface in each nacreous layers were observed through a SEM (Scanning Electron Microscope), and the diffraction pattern on SEM images was analyzed using FFT (Fast Fourier Transform). Through these analysises, it was verified that the color and optical characteristics are closely related to the structure of nacreous layers. Incident angle-dependent reflection spectrum was used to examine the phenomena of color differenceas the direction of observation. Quantified values on the color change were obtained by CIE $L^*a^*b^*$ color scale. Using this research, database for the characteristics of natural pearl shells can be established, and the precise analytic method for observation of pearl shells was suggested.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.47-58
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• 2024

This study were conduced experimentally to analyze the heat-generating performance, flexural strength, and microstructure of conductive mortar mixed with micro steel fiber and multi-wall carbon nanotube (MWCNT). In the conductive mortar heat-generating performance and flexural strength tests, the mixing concentration of MWCNT was selected as 0.0wt%, 0.5wt%, and 1.0wt% relative to the weight of cement, and micro steel fibers were mixed at 2.0vol% relative to the volume. The performance experiments were conducted with various applied voltages (DC 10V, 30V, 60V) and different electrode spacings (40 mm, 120 mm) as parameters, and the flexural strength was measured at the curing age of 28 days and compared and analyzed with the normal mortar. Furthermore, the surface shape and microstructure of conductive mortar were analyzed using a field emission scanning electron microscope (FE-SEM). The results showed that the heat-generating performance improved as the mixing concentration of MWCNT and the applied voltage increased, and it further improved as the electrode spacing became narrower. However, even if the mixing concentration of MWCNT was added up to 1.0 wt%, the heat-generating performance was not significantly improved. As a result of the flexural strength test, the average flexural strength of all specimens except the PM specimen and the MWCNT mixed specimens was 4.5 MPa or more, showing high flexural strength due to the incorporation of micro steel fibers. Through FE-SEM image analysis, Through FE-SEM image analysis, it was confirmed that a conductive network was formed between micro steel fibers and MWCNT particles in the cement matrix.

• Journal of Distribution Research
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• v.17 no.5
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• pp.85-111
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• 2012

Introduction : The purpose of this study was to examine the relationship between perceptual characteristics of consumers and intent of relational continuance for PB(Private Brand) products in discount stores. This study was conducted as an empirical study based on survey. For the empirical study, factors of PB products as characteristics perceived by consumers such as perceived quality, store image, brand image and perceived value were deduced from preceding studies. The effect of such factors on intent of relational continuance mediated by brand trust and brand equity of PB products was structurally examined. Research Model : Based on theory analysis and hypotheses, constructed a Structural Equation Model(SEM). The research model is shown in Figure 1. Research Method : This paper is based on s qualitative study of selected literature and empirical data. The survey for empirical study was carried out on consumers in Gyeonggi and Busan between January 2012 and May 2012. 300 surveys were distributed and 253 (84.3%) of them were returned. After excluding omissions and insincere responses, 245 surveys (81.6%) were used for final analysis as effective samples. Result : First of all, the Reliability was carried out for instrument used. The lower limit of 0.7 for Cronbach's Alpha as suggested by Hair et al. (1998). And Construct validity was established by carrying out exploratory factor analysis by Varimax rotation for all. Four factor result for the consumer's perceptual characteristics of PB Products, two mediating factors and one dependent factor. All constructs included in research framework have acceptable validity and reliability. Table 1 shows the factor loading, eigen value, explained variance and Cronbach's alpha for each factor. In order to assure validity of constructs, I implemented Confirmatory Factor Analysis (CFA), using AMOS 20.0. In confirmatory factor analysis, researcher can take control over the specification of indicators for each factor by hypothesizing that a specific factor is loaded with the relevant indicators. Moreover, CFA is particularly useful in the validation of scale for the measurement of specific construct. CFA result summarized Table 2 shows that the fit measures of all constructs fulfill the recommended level and loadings are significant. To test causal relationship between constructs in the research model, used AMOS 20.0 that provides a graphic module as method for analysing Structural Equation Modeling. The result of hypothesis test is shown in Table 3. As a result of empirical study, perceived quality, brand image and perceived value as selected attributes for PB products showed significantly positive (+) effect on brand trust and brand equity. Furthermore, brand trust and brand equity showed significantly positive (+) effect on intent of relational continuance. However, store image of discount stores selling the PB products was analyzed to have positive (+) effect on brand trust and no significant effect on brand equity. Discussion : Based on the results of this study, the relationship between overall quality, store image, brand image and value perceived by consumers about PB products and intent of relational continuance was structurally verified as being mediated by brand trust and brand equity. Looking at the results, a strategic approach that maximizes brand trust and equity value for PB products by large discount stores is required on top of basic efforts to improve quality, brand image and value of PB products in order to maximize consumer's intent of relational continuance and to continuously attract repeated purchase of products.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.103-106
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• 2002

The applicability of models based on fractal morphology to characterize $(Ba\;Sr)TiO_{3}$ thin film surfaces was investigated. The fractal morphology of coated barium strontium titan oxide thin film surfaces was described using fractal dimension from scanning electro microscopy image. The $(Ba\;Sr)TiO_{3}$ coating were deposited on silicon wafers using $(Ba\;Sr)TiO_{3}$ solution and spin coater. BST solution was composited by mol ratio, and then spin-coated from 3 times to 5 times coating on $Pt/SiO_{2}/Si$ substrate. Qualitative thin film analysis was performed with scanning electro microscopy (SEM), and surfaces parameters such as average grain diameter, roughness exponent and fractal dimension were determined.

• Journal of Korean Society for Quality Management
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• v.45 no.2
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• pp.275-292
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• 2017

Purpose: This study is designed to explore web-site service quality factors in job information site for high quality human resource, and to test relationship among web service quality, image, user satisfaction, relationship quality, and loyalty intention. Methods: A survey tool was questionnaire that had obtained validity and reliability through literature survey and pretest survey, and sample 214 was analyzed through SEM using SPSS21.0 and AMOS21.0. Results: Web design and information offer affect Image and user satisfaction. Also, relationship quality turned out to be an important mediator between image and loyalty intention and between customer satisfaction and loyalty intention. Conclusion: This study shows that two factors in via of relationship quality, were important factors that related companies have to emphasize to raise performance, Also, in order to raise loyalty intention of customer, marketer should exert to well manage relationship quality having significance as a mediator.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.98-98
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• 2003

비정질 실리콘 박막을 태양전지, 박막 트랜지스터, 이미지 센서, 컬러 디텍터 등에 적용하기 위한 많은 연구가 진행되고 있다. 이중 태양전지에 적용하기 위한 비정질 실리콘 박막은 p/i/n 다이오드 구조를 형성하게 되는데, 태양전지의 효율을 증가시키기 위해 결정질을 형성하거나 실리콘 화합물 박막을 적용한다. 본 연구에서는 비정질 태양전지의 흡수층(absorption layer)으로 사용되는 수소화된 비정질 박막의 결정화에 수소의 희석비가 미치는 영향을 파악하고자 하였다. PECVD 장비로 실란(SiH$_4$)과 수소(H$_2$) 가스를 이용하여 실리콘 박막을 증착하였고, 수소의 희석비(dilution ratio)를 변화시켜 비정질 실리콘 박막 내에 결정질 실리콘이 형성되는 정도를 관찰하였다. SEM과 Raman Spectroscopy를 이용해 박막의 두께 및 결정화도를 측정하였다. 실란에 대한 수소의 희석비가 증가할수록 증착률은 낮아지지만, 결정화도가 높아지는 것을 관찰할 수 있었다. 본 연구에서 형성한 결정질 실리콘 박막을 태양전지의 흡수층에 적용하면 효율 증가에 크게 기여할 것으로 판단된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.916-919
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• 2017

최근 딥러닝의 발달로 인해 Sentiment analysis분야에서도 다양한 기법들이 적용되고 있다. 이미지, 음성인식 분야에서 높은 성능을 보여주었던 Convolutional Neural Networks (CNN)은 최근 자연어처리 분야에서도 활발하게 연구가 진행되고 있으며 Sentiment analysis에도 효과적인 것으로 알려져 있다. 기존의 머신러닝에서는 lexicon을 이용한 기법들이 활발하게 연구되었지만 word embedding이 등장하면서 이러한 시도가 점차 줄어들게 되었다. 그러나 lexicon은 여전히 sentiment analysis에서 유용한 정보를 제공한다. 본 연구에서는 SemEval 2017 Task4에서 제공한 Twitter dataset과 다양한 lexicon corpus를 사용하여 lexicon을 CNN과 결합하였을 때 모델의 성능이 얼마큼 향상되는지에 대하여 연구하였다. 또한 word embedding과 lexicon이 미치는 영향에 대하여 분석하였다. 모델을 평가하는 metric은 positive, negative, neutral 3가지 class에 대한 macroaveraged F1 score를 사용하였다.

• Tribology and Lubricants
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• v.26 no.2
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• pp.122-128
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• 2010

Focused Ion Beam (FIB) has been used for site-specific TEM sample preparation and small scale fabrication. Moreover, analysis on the surface microstructure and phase distribution is possible by ion channeling contrast of FIB with high resolution. This paper describes FIB applications and deformed surface structure induced by sliding. The effect of FIB process on the surface damage was explored as well. The sliding experiments were conducted using high purity aluminum and OFHC(Oxygen-Free High Conductivity) copper. The counterpart material was steel. Pin-on-disk, Rotational Barrel Gas Gun and Explosively Driven Friction Tester were used for the sliding experiments in order to investigate the velocity effect on the microstructural change. From the FIB analysis, it is revealed that ion channeling contrast of FIB has better resolution than SEM and the tribolayer is composed of nanocrystalline structures. And the thickness of tribolayer was constant regardless of sliding velocities.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.167.2-167.2
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• 2017

수지상 구리분말은 하나의 상(statue)이 복수의 접점(contact point)를 제공하며 표면적이 넓은 구조적인 특징으로 인해 발열기판 전도성 페이스트 등 다양한 전기 전가 분야에 활용되어왔다. 때문에 본 연구에서는 전해도금방법으로 수지상 구리분말이 형성될 때 첨가제가 수지상의 형상에 어떠한 영향을 미치는지 분석하였다. 첨가제는 PEG, JGB를 사용하여 농도별로 실험을 진행하였다. SEM 이미지 분석결과 첨가제가 추가함에 따라 수지상이 미세해지며 첨가제의 농도가 증가함에 따라 DAS(dendrite arm spacing)값이 감소하여 표면적이 증가하였다. BET 비표면적 분석결과 PEG($1.882m^2/g$)보다 JGB($2.119m^2/g$)에서 표면적을 넓히는 효과가 뛰어났다.