• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.31 no.7
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• pp.65-70
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• 2002

지구의 오존층을 보호하기 위한 몬트리올 의정서가 1987년 채택된 이후 오존층 파괴물질의 사용이 점차 감소되고 있다. 선진국의 경우 1995년 말부터 CFC냉매의 생산을 전폐하였고, HCFC냉매의 경우는 2020년 전폐를 목표로 대체냉매를 이용한 응용 기술개발 및 제품 생산이 진행되고 있다. 가정용 냉장고 및 차량용 에어컨에는 R-12의 대체냉매로 R-134a가 도입되었으며, 유럽을 중심으로 냉장고에는 HC계 냉매인 R-600a도 대체냉매로 사용되고 있다. 가정용 에어컨에는 혼합냉매인 R-407c 와 R-410a가 R-22 냉매를 대체하여 적용되고 있다. 그러나 현재, CFC및 HCFC 대체 냉매로 많이 사용되고 있는 HFC계 냉매도 지구 온난화 지수가 대단히 큰 문제를 가지고 있다. 1997년 채택된 교토의 정서에는 HFC계 냉매가 온실효과가 가스 배출규제물질에 포함되어 있다. 이에 따라서 오존층의 파괴지수가 영이고 지구온난화지수도 거의 없는 자연냉매가 주목을 받게 되었으며, 자연 냉매의 하나인 이산화탄소 ($CO_2$R744) 냉매의 응용기술 및 제품개발 연구가 선진국을 중심으로 폭넓게 진행되고 잇다. 본고에서는 $CO_2$냉매의 일반적인 특성을 간단히 소개하고 일본에서 진행되고 있는 $CO_2$냉매를 적용한 급탕시스템의 제품개발 및 시장현황에 대해서 기술하기로 한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.90-90
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• 2017

물리서식처 분석 하천에서 유량에 따른 수심, 유속, 기층 등의 물리서식처 조건의 변화가 서식처 적합도에 미치는 영향을 수치모의를 통하여 분석하는 방법이다. 기존 물리서식처 분석은 어류를 중심으로 수생태계 평가 및 생태유량산정 등의 다양한 하천관리 문제에 적용되었다. 어류의 경우 수생태계의 최상위 포식자이며 상대적으로 모니터링하기에 용이하고 수생태계에 빠르게 반응하고 이동 및 이주가 단기간에 나타나는 특징이 있다. 또한 상업 및 레크리에이션으로의 활용도가 높기 때문에 사회적인 이목이 어류로 집중되었다. 따라서 많은 연구들이 어류를 중심으로 물리서식처 분석을 실시하였으며, 저서무척추 동물에 대한 분석은 미흡한 실정이다. 저서무척추 동물은 어류의 중요한 먹이원이자 수생태계의 건강성을 나타내는 중요한 지표로 활용되고 있으므로, 수생태계의 통합 및 먹이사슬의 보존을 위하여 저서무척추 동물에 대한 물리서식처 평가는 중요하다. 이 연구의 목표는 하천에서의 저서무척추동물의 군집을 평가할 수 있는 서식처모형을 제시하는데 있다. 이를 위해 저서무척추 동물을 서식기능군에 근거한 기는무리, 붙는무리, 헤엄치는 무리, 굴파는 무리로 분류하여 서식처 적합도 지수를 제하고 보철거 사례에 적용하여 모형의 검증성을 확인하였다.

• Korean Journal of Construction Engineering and Management
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• v.15 no.4
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• pp.107-118
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• 2014

Electrical Construction industry uses Construction industry's statistical data for business outlook. Because there are not electrical construction business view's statistical data. It has own unique characteristic which is different from construction industry. So it must have a electrical construction Business Index. This study was focused on developing the business index of electrical construction business. Electrical construction business index consists of electrical construction composite Index(ECI) and the electrical construction business survey index(EBSI). This study experimentally analyzes the business views of electrical construction industry in 2/4 quarter of 2014. The leading Index of ECI indicates -0.4% compared with 1/4 quarter of 2014, coincidence index also shows that electrical construction industry's business cycle is in an economic downturn. EBSI is 83.5 in 2/4 quarter of 2014, down from 95.2 in 1/4 quarter of 2014. It means that electrical construction company has a pessimistic prediction. As a result we know that the Business Index of Electrical Construction Business shows similar results. It is expected to make contribution for electrical contractors to establish management strategies and prepare responses to economic changes by providing information about economic trends of electrical construction business and forecasting future economy.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.113-119
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• 2020

This study analyzed the relationship between consumers' awareness of marine products and the food index level, which is a sub-domain of the Pukyong Maritime Index. Specifically, the evaluation of marine products by Korean consumers verified the relationship between taste, nutrition, diversity, price, and safety-related systems and the food index. The analysis results were as follows. First, it was found that consumers' awareness of marine products had a significant positive correlation with the food index. Second, as a result of the regression analysis, the food index had an effect on the order of nutrition, taste, and price. These findings are required to understand consumers' awareness of aquatic products, and the food index can be used as the center of northeast asia sea region to provide a framework for improving consumer's satisfaction.

• International Area Studies Review
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• v.13 no.3
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• pp.583-611
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• 2009

This study aims at analysing the export competitiveness of the six largest countries which have the highest market share in world automobile market, namely Japan, USA, China, Germany, South Korea and France for the last seven years between 2000 and 2006 in Chinese automobile market by using revealed comparative advantage index(RCA), comparative advantage index by country (CAC) and exporting similarity index(ESI). On analysis of the RCA index, it showed that the export competitiveness of Korean automobile in the world market was high following Japan and Germany, but it ranked the lowest competitiveness among the six trade competitors in Chinese automobile market. In other side, it is also made sure that the formidable competitors of Korean automobile export in global market are Germany and Japan. Therefore, South Korea needs to raise its ability to adjust to improvement of the international competitiveness in exports through close cooperation between government and automobile export enterprise and consistent monitoring about Chinese automobile industry and market.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.105-113
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• 2006

Construction cost index is generally used to estimate the new project cost based on past construction data and to adjust the contract cost when the price change of various articles and items of expenditure composing the contract occurs. In Korea, it is mostly used for modulation of construction contract cost due to fluctuation of prices. However the method for making cost index had some problems in calculating cost index of each expenditure item that could not properly reflect the change of construction cost. To supplement these problems, the research of developing construction cost index has been executed. Through the precedent research, these problems were partially resolved but still remain. Therefore this research proposes the method for making cost index that utilizes representative items of labor, material, equipment by analyzing bill of quantity of road construction, through analysis and comparison of precedent studies. By using this method, it is expected to solve the problems which were not reflected in preceeding studies.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.281-291
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• 2020

This study used Gauss-Poisson jump diffusion process on standard assets to estimate the statutory reserves of Variable Annuity (VA) guarantees specified in Korean bylaw of insurance supervision and calculated guarantee fees and risks based on the model to see the effect of considering the jumps. Financial assets, except KOSPI 200, have fat-tailed return distributions, which is an indirect evidence of discontinuous jumps. In the case of a domestic stock index and foreign stock indexes(Korean Won), guarantee fees and risks decrease when jumps are considered in models of underlying assets. This is explained by decreases in standard deviations after the jump diffusion is considered. On the other hand, in the case of domestic bond indexes and a foreign bond index(Korean Won), guarantee fees and risks tend to increase when jumps are considered. Results from a foreign stock index(US Dollar) and a foreign bond index(US Dollar) were opposite to those from the same kinds of Korean Won indexes. We conclude that VA guarantee fees and risks may be under or over estimated when jumps are not considered in models of underlying assets.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.123-129
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• 2010

The purpose of study is to investigate the correlation between the Lyapunov exponent (LE) and the displacement of the center of gravity (DCG) for clarifying walking stability on the treadmill. From fifteen young healthy subjects volunteered, lower extremity joint angles were recorded using a three-dimensional motion capture system with reflective markers. The anteroposterior DCG and the LE were calculated by a commercial software. A linear correlation between LE and DCG (p<0.05) showed that LEs compensated for walking distance on the treadmill walking. However, LEs were found to be independent of self-selected walking speeds by a negligible correlation between LE and the Froude number (p>0.05).

• Journal of the Korean Society for information Management
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• v.29 no.2
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• pp.193-204
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• 2012

The characteristics of citation and centrality measures in citation networks can be identified using multiple linear regression analyses. In this study, we examine the relationships between bibliometric indices and centrality measures in an article-level co-citation network to determine whether the linear model is the best fitting model and to suggest the necessity of data transformation in the analysis. 703 highly cited articles in Physics published in 2004 were sampled, and four indicators were developed as variables in this study: citation counts, degree centrality, closeness centrality, and betweenness centrality in the co-citation network. As a result, the relationship pattern between citation counts and degree centrality in a co-citation network fits a non-linear rather than linear model. Also, the relationship between degree and closeness centrality measures, or that between degree and betweenness centrality measures, can be better explained by non-linear models than by a linear model. It may be controversial, however, to choose non-linear models as the best-fitting for the relationship between closeness and betweenness centrality measures, as this result implies that data transformation may be a necessary step for inferential statistics.

• The Journal of the Korea Contents Association
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• v.15 no.10
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• pp.387-399
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• 2015

Recently collaboration network is generated to find out experts in their field as potential collaborators in health care sector. In this paper, the co-author network of a National Cancer Center researcher was generated for identifying each researcher's role and collaborative research pattern. The co-author network of 2,437 authors was extracted from 1,194 SCI(E) publications from 2000 to 2010 and author's role was analyzed by author's centrality value. Centrality reflecting only the number of papers and centrality weighted by the paper number, impact factor, and authorship contribution was evaluated. On the comparison with simple degree centrality value and the weighted degree centrality, difference of value was statistically significant(t=11.66, p=0.00). Co-author network considering various variables of the paper provides more objective figure of researcher's role. This suggests that co-author network could be more effective in identifying potential collaborators.