• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.63.1-63.1
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• 2010

실리콘 박막 태양전지의 효율을 향상시키기 위해 밴드갭이 다른 흡수층을 적용한 tandem형 적층 태양전지를 이용하고 있다. 일반적으로 1.7eV이상의 밴드갭이 큰 비정질 실리콘을 이용하여 단파장의 빛을 흡수하고, 상대적으로 낮은 1.1eV 정도의 밴드갭을 갖는 미세결정 실리콘 층으로 장파장을 흡수하게 된다. 이렇게 연결된 tandem형 태양전지의 효율을 극대화하기 위해서는 각 태양전지에서 발생하는 전류 밀도를 일치시키는 것이 필요하다. 이를 위해 비정질 실리콘의 두께가 증가되는 경우가 있는데 이러한 경우 비정질 실리콘의 광열화 특성(Lihgt-induced degradation)으로 안정화 효율이 감소하게 된다. 따라서 비정질 실리콘 태양전지의 전류 밀도를 향상 시켜 두께를 최소화하는 것이 매우 중요하다. Tandem형 태양전지에서 비정질 실리콘 태양전지의 전류 밀도를 향상시키기 위해 두 개의 전지사이에 광 반사층을 적용하여 태양전지를 제조하게 된다. 이러한 경우 비정질 실리콘의 전류 밀도는 증가하지만, 광 반사 층의 장파장 흡수로 인하여 하부 태양전지의 전류 밀도 감소가 더 커지게 되어 전체 발생 전류 밀도는 오히려 감소하게 된다. 본 논문에서는 비정질 실리콘의 밴드갭을 제어하여 광 흡수 파장 영역 확대로 전류 밀도를 향상시키는 연구를 진행하였다. PECVD의 RF power 조건을 제어하여 1.75eV에서 1.67eV까지 밴드갭을 변화시켰다. 이와 같은 조건의 박막을 광 흡수층으로 갖는 p-i-n 구조의 비정질 실리콘 태양전지를 제작하였다. i층의 밴드갭이 감소됨에 따라 장파장 영역의 흡수가 확대되어 전류 밀도가 증가 하였지만, Voc의 감소가 컸다. 이는 i층의 밴드갭이 좁아짐에 따라 p층과의 불연속성이 커졌기 때문이다. 이러한 악영향을 줄이기 위해 p층과 i층 사이에 buffer층을 삽입하여 태양전지를 제작하였다. 이와 같은 최적의 buffer층 삽입을 통하여 불연속성을 줄임으로써 Voc의 상승효과를 확인하였다. 본 연구의 결과로 좁은 밴드갭을 갖는 광 흡수 층을 적용하여 전류 밀도를 향상시키고, 최적화된 buffer층 삽입으로 Voc를 향상시킴으로써 고효율의 비정질 실리콘 태양전지를 제작하였다. 이를 tandem형 태양전지에 적용할 경우 초기 효율뿐만 아니라 얇은 두께에서 제조할 수 있기 때문에 광열화 특성이 향상되어 안정화 효율의 증가를 가져올 수 있다.

• The Journal of Information Systems
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• v.24 no.2
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• pp.209-240
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• 2015

Purpose This study investigates the relationships between various attributes of smart banking (convenience, security, convergence, and economy), user features (familiarity and innovativeness), perceived usefulness, trust, satisfaction, and continuance intentions and provides a comparison of Google's Android OS and Apple's iOS. Design/methodology/approach We considered a sample of 245 respondents and used structural equation modeling to analyze the data. Findings The results indicate that convergence and familiarity significantly affected perceived usefulness and that security and economy significantly affected perceived trust in smart banking services. The relationships of security, economy, and innovativeness to perceived usefulness and those of convenience and familiarity to perceived trust were stronger for the Android OS than for iOS. The study contributes by proposing an integrated framework and providing a comparison between the Android OS and iOS in the context of smart banking.

• Journal of Digital Contents Society
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• v.2 no.2
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• pp.103-115
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• 2001

This paper proposes the two algorithms which generate a minimal decision rule and approximate inference operation, adapted the rough set and the factor space theory in fuzzy knowledge base. The generation of the minimal decision rule is executed by the data classification technique and reduct applying the correlation analysis and the Bayesian theorem related attribute factors. To retrieve the specific object, this paper proposes the approximate inference method defining the membership function and the combination operation of t-norm in the minimal knowledge base composed of decision rule. We compare the suggested algorithms with the other retrieval theories such as possibility theory, factor space theory, Max-Min, Max-product and Max-average composition operations through the simulation generating the object numbers and the attribute values randomly as the memory size grows. With the result of the comparison, we prove that the suggested algorithm technique is faster than the previous ones to retrieve the object in access time.

• Korean Journal of Construction Engineering and Management
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• v.10 no.4
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• pp.151-164
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• 2009

Strategic alliances developed as formalized inter-organizational relationships are core vehicles to share information, resources and knowledge. The structural characteristics of strategic network constructed by strategic alliances have been important agenda in strategic management discipline. This paper has two folds in analysing the strategic network formulated by project level alliances in Korean construction industry. First, we investigate the strategic network using the tools and methods of social network analysis, such as centrality, cohesion, structural equivalence, and power law. Second, the performance of firms within networks are analysed longitudinally with panel data analysis. We have found that the strategic networks in this industry has scale-free characteristics, where the degree distribution fits the power law, and the vertically equivalent structure is clear. We also present that the performance of firms are continuously affected by the degree centrality of firms in this network for the last 10 years.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.63-70
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• 2001

Changes in concentrations of dissolved oxygen, ammonia, nitrate, pH, Fe and Mn were monitored from the laboratory incubation of an benthic chamber. The extent of sedimentary organic carbon and nitrogen decomposition was quantified by applying the concentration data to the chemical reaction equations of early diagenesis. The patterns of the concentration changes, observed during the 237 hr long incubation experiment, made it possible to divide the entire experiment period into four characteristic sub-periods (0-9 hr, 9-45 hr, 45-141hr, 141-237 hr). C/N ratio, estimated for each sub-period, was 6.63, 1.49, 0.81 and 0.02, respectively. This sequential decrease in C/N ratio suggests that during the incubation experiment dissolved nitrogen species diffuse more out of the sediment than dissolved carbon species. Greater diffusion of nitrogen indicates the preferential decomposition of organic nitrogen during early diagenesis of sedimentary organic matter. Comparison of the concentration data (sedimentary organic carbon and nitrogen, porewater organic carbon and ammonia)between the sediment pre and post incubation also indicates the preferential decomposition of nitrogen during early diagenesis of sedimentary organic matter.

• Journal of the Korean School Mathematics Society
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• v.13 no.2
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• pp.263-287
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• 2010

The purposes of the study were to investigate how children define a triangle, their reasoning types in identifying examples and non-examples of a triangle, and the relationship between their reasoning types and geometrical levels. Twenty-nine students consisted of 3th to 6th grades were involved in the study. Using the van Hiele levels of geometrical thought, children's reasoning types for identifying a figure as a triangle or non-triangle were categorized into visual reasoning, reasoning based on the figure's attributes and formal reasoning. The figure's attributes were further divided into critical and non-critical attributes. Most children identified a figure as a triangle or non-triangle based on critical attributes of the figure(e.g. closed figure, three, vertices, straight sides etc.) Some children identified a figure based on non-critical attributes of the figure(e.g. the length of the sides, the measurement of the angles, or the orientation of the figure). Particularly, some children who had lower levels of geometry identified a figure using visual reasoning, taking in the whole shape without considering that the shape is made up of separate components.

• Journal of Korea Multimedia Society
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• v.17 no.1
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• pp.77-93
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• 2014

Kinetic typography has been suggested to express emotions in computer-mediated communication (CMC) by empowering static texts with dynamic attributes, where conversations occur primarily in text-based forms. In this work, we investigate whether pre-defined kinetic typography effects are capable of delivering emotions, and further, which specific attributes of kinetic typography arouse such emotions. The results show that emotional response of users were corresponding to the emotions intended by experts, indicating that pre-defined kinetic typography is an applicable way to express emotions consistently in CMC. Also, results demonstrate some key attributes that derive certain levels of mood and energy respectively. Energy level turned out to be affected by the font size, transparency, direction of movement, amount of movement, velocity, and acceleration of the text, while mood level was influenced by the transparency, direction of movement, regularity in movement, and speed of the text.

• Korean Journal of Cognitive Science
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• v.25 no.1
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• pp.25-49
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• 2014

Advertisement for one type of product competes against another type using different advertising strategies. It is important to know which factors influence people's perception of the message within the advertisement and their formation of attitudes towards the advertisement. Using multidimensional scaling, this study investigated what main factors were important when people perceive beverage advertisements on TV. A positioning map was constructed based on similarity ratings of 14 drink advertisements. We examined the meaning of the three dimensions of the positioning map by asking a different group of participants to rate on components of attention, attitudes toward advertisements and products, and intention to purchase the product in each advertisement. It was found that three dimensions in the map was attention to content, color, and motion respectively. More importantly, the attentional component to content was related to the attitude of affection and action toward a beverage introduced in advertisement. These results suggest that content-based attention in advertisements induces a positive attitude toward the advertisements.

• Journal of Labour Economics
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• v.30 no.2
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• pp.87-118
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• 2007

Using KRIVET's Graduates Economic Activities Survey for 2005, this article examines the relationship between university ranking and labor market outcome, with a focus on wage differentials existing between provincial and Seoul metropolitan area university graduates. According to the analysis results, the average monthly wage for provincial university graduates was 1,747.7 thousand Korean won, which is 11.5% lower than that for graduates of universities in the Seoul metropolitan area. School effects on individual wage were estimated to about 12.2% after applying Hierarchical Linear Model technique, which means that university explains only an insignificant part of the total variance in wage among graduates. After controlling for the selection bias, the ability difference between the two areas, by applying the Heckman type 2SLS wage function and Neumark wage differential decomposition technique, the wage gap resulting from the segregation was not identified. This implies that, to a significant extent, the wage gap between provincial and Seoul metropolitan university graduates is attributed to the difference in productivity among individual graduates, rather than to the wage segregation. Also, the estimated wage function by applying Quantile Regression technique indicates that there does not exist any significant wage segregation difference by wage quantile.

• The KIPS Transactions:PartC
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• v.18C no.5
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• pp.361-368
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• 2011

In this study, we present a method for efficiently aggregating networks state information required to determine feasible paths in transport networks that uses the source routing algorithm for hierarchical QoS routing. It is proposed to transform the full mesh topology whose Service Boundary Line serves as its logical link into the star topology. This is an aggregation method that can be used when there are two or more QoS parameters for the link to be aggregated in an asymmetric network, and it improves the information accuracy of the star topology. For this purpose, the Service Boundary Line's 3 attributes, splitting, joining and integrating, are defined in this study, and they are used to present a topology transformation method. The proposed method is similar to space complexity and time complexity of other known techniques. But simulation results showed that aggregated information accuracy and query response accuracy is more highly than that of other known method.