• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.814-819
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• 2006

This research is on the design and introducing of integrated thermal performance of super energy saying building, called 3 Liter house which can be sustained with 3 liter oil(kerosene) per $yr.m^2$. 3 liter houses(Passive houses) offer extended living comfort with only 15 to 20% of the space heating demand of conventional new building. To achieve this purpose, the efficiency of building components is improved, such as walls, windows or ventilation system and the construction technology is improved, such as the prevention of thermal bridge and the air tightness. The fuel cell is used as alternative energy. Energy consumption of 3L house is 2.08 [liter/$yr.m^2$] in monitoring result of $2006/2/1{\sim}2/7$ and ACH50 is 0.67 in result of Blow Door Test, therefore 3L House is well- insulated and well- airtighted house.

• 유통과학연구
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• 제12권4호
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• pp.23-30
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• 2014

Purpose - The purpose of this study is to analyze the efficiency of retail businesses by dividing domestic retailers into discount stores, super supermarkets (SSMs), and department stores. It suggests retail-business investment strategies by using data environment analysis (DEA) to analyze how input elements such as store area, parking lot area, number of employees, and sales management expenses for the convenience of customers positively affect business performance measurements such as sales and visiting customers per day. Research Design, Data, and Methodology - The DEA model calculates a ratio of the weighted mean of various inputs to the weighted mean of various outputs and measures the efficiency of a specific decision making unit (DMU). The study included 19 companies (five discount store DMUs, ten SSM DMUs, and four department store DMUs). Because the business elements and sizes of retail store DMUs used in this analysis are different, average per-store input and output variables were used. Data were collected from "The Yearbook of Retail Industry in Korea (2012)." DEA analysis was used to determine differences in efficiency among discount stores, SSMs, and department stores in terms of the business elements of each retail business. It was also used to determine what business elements were excessively invested in by comparing and analyzing efficiency by business elements using SPSS software's ANOVA (Analysis of Variance). Results - The CCR and BCC efficiency analysis found that the efficiency of discount stores is low. We believe that the saturation state of discount stores is a major factor. The ANOVA analysis confirms the VRS hypothesis with a statistically significant difference among the three groups, based on an analysis confidence interval of 95%. CRS and SE were not found to be significantly different among the three groups. As for the post hoc test, which concretely shows differences by group, the Scheffe's multiple comparison analysis test found the average differences between group 1 (discount stores) and group 2 (SSM) to be statistically significant. Conclusions - The DEA efficiency analysis implies that investment in input elements, including store area, parking lot area, and sales management expenses, were excessive in the case of discount stores, while SSMs need to invest more in promotion activities such as gifts, events, and coupons for customer management. Department stores have found that small companies invest excessively in input elements. Department stores need to invest in differentiated shopping mall complexes. This study was limited in acquiring statistical data; various input variables which might have shown more secure customer management and promotional expenses could not be applied. As the study was limited in various aspects of the efficiency analyses because financial analyses of the companies and of causal relationships, including satisfaction and loyalty of visiting customers, were not done, these aspects will be examined in the next study.

• 동력기계공학회지
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• 제9권2호
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• pp.81-87
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• 2005

This study is numerical analysis on the increasing temperature characteristics of vaporizer fin for liquefied natural gas with super low temperature. Existing LNG vaporizers use the direct contact heat transfer mode where the extreme super low temperature LNG of $-162^{\circ}C$ flows inside of the tubes and about $20^{\circ}C$air flows on outside of the fin. Recently, the vaporizers with great enhanced performance compared to conventional type have been developed to fulfill these requirements. The vaporizing characteristic of LNG vaporizer with air as heat source has a fixed iced. These characteristic cause a low efficiency in vaporizer, total plant cost and installing space can be increased. The vaporizing characteristics of LNG via heat exchanger with air are analytically studied for an air heating type vaporizer. This study is intended to supply the design data for the domestic fabrication of the thickness and angle vaporizer fin. Governing conservation equations for mass, momentum and energy are solved by STAR-CD based on an finite volume method and SIMPLE algorithm. Calculation parameter is fin thickness, setup angle and LNG temperature. If the vaporization performance of the early stage and late stage of operating is considered, the case of ${\phi}=90^{\circ}$ was very suitable. In this paper was estimated that the heat transfer was most promoted in case of THF=2mm.

• 방송공학회논문지
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• 제17권2호
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• pp.344-353
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• 2012

본 논문에서는 이산 웨이블릿 변환(Discrete Wavelet Transform: DWT)을 이용한 새로운 초고해상도 기법을 제안한다. 기존의 단일 영상에 적용되는 초고해상도 기법들의 경우 영상에서의 고주파 대역을 찾기 위하여 확률 기반의 방법들을 사용하였다. 그로 인한 연산의 복잡도 증가는 처리시간 증가라는 문제점을 발생시켰다. 제안된 기법에서는 고주파 대역을 찾기 위한 방법으로 DWT를 이용한다. DWT 수행 시 수반되는 다운 샘플링 과정을 수행하지 않음으로써 입력 받은 영상과 동일한 크기의 고주파 부대역(sub-band)들을 생성하고, 이 부대역들과 입력 받은 영상을 조합하여 이산 웨이블릿 역변환(Inverse Discrete Wavelet Transform: Inverse DWT)을 수행함으로써 고해상도의 영상을 획득한다. 제안하는 기법에서 사용한 실험영상은 원본영상($512{\times}512$)을 다운 샘플링하여 획득한 실험영상($256{\times}256$)을 사용한다. 실험을 통하여 제안된 기법이 기존의 보간법에 비해 향상된 효율을 보이며, 확률 기반의 기법들에 비해 처리시간이 줄어드는 것을 확인하였다.

• 마케팅과학연구
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• 제16권1호
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• pp.1-11
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• 2006

저작권의 거래 및 통제를 매우 낮은 비용으로 구현한 DRM(Digital Right Management)에 의해 디지털 컨텐츠의 유통에 획기적인 변화가 가능할 것으로 생각된다. 본 논문은 DRM 기술의 도입에 의해 개별 이용자가 유통의 주체가 되는 초유통(Super Distribution)의 적용 가능성과 다양한 가격설정 방식이 적용될 수 있다는 점에 주목하였다. 우선 초유통을 통해 이용자들의 정보획득비용을 감소시키고 이를 통해 수요를 증가시킬 수 있으며 컨텐츠 제작자 측면에서도 유통에 따른 비용을 크게 감소시킬 수 있음을 논하였다. 또한 DRM은 기존의 총량가격 방식 이외에 사용기간 또는 사용 횟수 등 다양한 기준에 따른 가격설정을 가능하게 하며 이를 통해 기업의 이윤과 소비자 총효용 모두 증가할 수 있음을 보였다. 이러한 DRM 기술의 특성은 디지털 컨텐츠 유통의 효율성을 증대시키고 컨텐츠의 질과 다양성 및 가격정책을 통한 사업자들간 차별화를 가능케 하여 산업의 동적인 성장을 가속화 할 수 있을 것으로 생각된다.

• 한국통신학회논문지
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• 제38A권3호
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• pp.240-248
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• 2013

본 논문에서는 이산 웨이블릿 변환(Discrete Wavelet Transform: DWT)과 적응적 가중치 보간법을 이용한 효율적인 초해상도 기법을 제안한다. 기존의 단일 영상에 적용되는 초해상도 기법들의 경우, 영상에서의 고주파 대역을 찾기 위하여 확률 기반의 방법들을 많이 사용하였다. 따라서 연산의 복잡도가 증가하고 처리시간 증가라는 문제점을 발생시킨다. 제안된 기법에서는 고주파 대역을 찾기 위한 방법으로 DWT와 적응적 가중치 보간법을 이용한다. 먼저 주어진 영상에 대하여 DWT를 수행하고, 생성된 고주파 부대역(sub-band)들을 적응적 가중치 보간법을 이용하여 입력 받은 영상과 동일한 크기의 고주파 부대역을 생성한다. 이 부대역들과 입력 받은 영상을 조합하여 이산 웨이블릿 역변환(Inverse DWT : IDWT)을 수행함으로써 고해상도의 영상을 획득하게 된다. 실험을 위하여 원본 영상($512{\times}512$)을 다운 샘플링하여 실험 영상($256{\times}256$)을 획득한다. 실험을 통하여 제안된 기법이 기존의 보간법에 비해 향상된 효율을 보이며, 확률 기반의 기법들과 비슷한 성능을 갖지만 처리시간에서 많은 이득을 보이는 것을 확인할 수 있었다.

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.555-564
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• 2020

The purpose of this study is to analyze the efficiency of research institutes of futures companies, and to promote the development of futures market and real economy. This study employs DEA-solver software to conduct super-efficiency data envelopment analysis (SE-DEA), and also selects 40 representative futures research institutes in China as decision-making units (DMUs). For data of input and output indicators, we collect from the China Futures Association, Futures Daily, Hexun.com and Webstock.com respectively, and the time duration is the 103 trading days between from October 2019 to February 2020. Then the indicator for the strategy accuracy rate is calculated separately by analyzing the strategies published by each DMUs in public media. In conclusions, most institutes have excessive investment in human resources, and also have insufficient strategy accuracy rate and insufficient published research reports. The findings of this study suggest that Chinese futures companies need to improve the efficiency of research institutes, and better meet the demand of the financial market. In fact, the analysis of the efficiency of the futures company research institute has not been found in the literature worldwide, Application of DEA model in efficiency analysis of securities and futures research institutions and establishment of indicators are the innovations of this paper.

• 한국경영과학회지
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• 제39권3호
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• pp.23-40
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• 2014

This paper measures the operational efficiency of domestic online game companies and analyze its trends and patterns by using data envelopment analysis (DEA). DEA is a non-parametric approach to measuring the relative efficiency of decision-making units (DMUs) with multiple inputs and outputs. 14 online game companies are selected as DMUs and three inputs (number of employees, capital and asset) and three outputs (sales, operating profit and net profit) are selected as DEA variables. First, the output-oriented BCC model and super-efficiency model are employed to measure the static operational efficiency of the online game companies from 2003 to 2012. We also conduct the dynamic analysis with DEA window model to capture the trends of their operational efficiency influenced by internal and external environmental changes. The results are expected to provide fruitful implications for strategic decision making of online game companies and policy making for the online game industry.

• Journal of Power Electronics
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• 제16권6호
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• pp.2035-2044
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• 2016

In order to match the voltages between high voltage battery stacks and low voltage super-capacitors with a high conversion efficiency in hybrid energy sources electric vehicles (HESEVs), a high ratio bidirectional DC-DC converter with a synchronous rectification H-Bridge is proposed in this paper. The principles of high ratio step-down and step-up operations are analyzed. In terms of the bidirectional characteristic of the H-Bridge, the bidirectional synchronous rectification (SR) operation is presented without any extra hardware. Then the SR power switches can achieve zero voltage switching (ZVS) turn-on and turn-off during dead time, and the power conversion efficiency is improved compared to that of the diode rectification (DR) operation, as well as the utilization of power switches. Experimental results show that the proposed converter can operate bidirectionally in the wide ratio range of 3~10, when the low voltage continuously varies between 15V and 50V. The maximum efficiencies are 94.1% in the Buck mode, and 93.6% in the Boost mode. In addition, the corresponding largest efficiency variations between SR and DR operations are 4.8% and 3.4%. This converter is suitable for use as a power interface between the battery stacks and super-capacitors in HESEVs.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.866-869
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• 2015

시스템-온-칩(system-on-chip, SoC)내에 집적되는 소자의 수가 기하급수적으로 증가함에 따라 에너지 효율을 높이기 위한 전압 스케일링은 필수적인 요소가 되었다. 문턱전압 근처 동작(near-threshold voltage computing, NTC)은 칩 에너지 효율을 10배 가까이 향상시킬 수 있는 기술로서 전통적인 초 문턱전압 동작(super-threshold voltage computing, STC)의 한계를 극복할 수 있을 것으로 기대되고 있다. 저성능 매니코어(manycore) 시스템으로 동작하는 NTC는 에너지 효율을 극대화할 수 있지만 성능 유지를 위한 코어 수의 증가는 상당한 면적 증가를 수반한다. 본 논문에서는 성능, 전력 및 면적 간의 trade-off를 고려하여 면적 제약조건 하에서 NTC 코어 수 및 캐시 및 클러스터 크기 결정 알고리즘을 통해 요구 성능을 만족시키면서 전력 소모를 최적화하는 방법을 제안한다. 실험을 통해 면적 제약조건 속에서 기존의 STC 코어에서의 성능을 유지한 채 전력소모를 약 16.5% 감소시킬 수 있음을 보여준다.