• Journal of Power Electronics
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• 제15권5호
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• pp.1318-1328
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• 2015

The photovoltaic (PV) power conditioning system for small-scale applications has gained significant interest in the past few decades. However, the standalone mode of operation has been rarely approached. This paper presents a two-stage multi-level micro-inverter topology that considers the different operation modes. A multi-output flyback converter provides both the DC-Link voltage balancing for the multi-level inverter side and maximum power point tracking control in grid connection mode in the PV stage. A modified H-bridge multi-level inverter topology is included for the AC output stage. The multi-level inverter lowers the total harmonic distortion and overall ratings of the power semiconductor switches. The proposed micro-inverter topology can help to decrease the size and cost of the PV system. Transient analysis and controller design of this micro-inverter have been proposed for stand-alone and grid-connected modes. Finally, the system performance was verified using a 120 W hardware prototype.

• Asia pacific journal of information systems
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• 제25권4호
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• pp.763-783
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• 2015

Online customer reviews (i.e., electronic word-of-mouth) has gained considerable interest over the past years. However, a knowledge gap exists in explaining the mechanisms among the factors that determine the product sales in online retailing environment. To fill the gap, this study adopts a principal-agent perspective to investigate the effect of customer reviews and customer incentives on product sales in online retail stores. Two customer review factors (i.e., average review ratings and the number of reviews) and two customer incentive factors (i.e., price discounts and special shipping offers) are used to predict product sales in regression analysis. The sales ranking data collected from the video game titles at Amazon.com are used to analyze the direct effects of the four factors and the interaction effects between customer review and customer incentive factors to product sales. Result reveals that most relationships exist as hypothesized. The findings support both the direct and interaction effects of customer reviews and incentive factors on product sales. Based on the findings, discussions are provided with regard to the academic and practical contributions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.914-934
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• 2016

In the mobile distributed environment, an entity may move across domains with great frequency. How to utilize the trust information in the previous domains and quickly establish trust relationships with others in the current domain remains a challenging issue. The classic trust models do not support cross-domain and the existing cross-domain trust models are not in a fully distributed way. This paper improves the outstanding Certified Reputation (CR) model and proposes a Lightweight Cross-domain Trust (LCT) model for the mobile distributed environment in a fully distributed way. The trust certifications, in which the trust ratings contain various trust aspects with different interest preference weights, are collected and provided by the trustees. Furthermore, three factors are comprehensively considered to ease the issue of collusion attacks and make the trust certifications more accurate. Finally, a cross-domain scenario is deployed and implemented, and the comprehensive experiments and analysis are conducted. The results demonstrate that our LCT model obviously outperforms the Bayesian Network (BN) model and the CR model in our cross-domain scenario, and significantly improves the successful interaction rates of the honest entities without increasing the risks of interacting with the malicious entities.

• 한국콘텐츠학회논문지
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• 제12권6호
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• pp.160-169
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• 2012

국내 유일의 과학전문채널인 'YTN사이언스 TV'는 과학 대중화라는 그간의 성과와 의의에도 불구하고 시청률 저조와 채널 접근의 한계로 여전히 어려움을 겪고 있어 이에 대한 개선방안이 시급하다. 본 연구는 과학전문채널의 활성화를 위해 재정적 관점에서 해외 유사채널과 비교함으로써 바람직한 대안과 발전과제를 모색하고자 한다. 공익성 구현과 상업성을 동시에 추구하며 성공적인 해외 채널 진출과 자국민에 대한 과학교육에 이바지하고 있는 BBC Knowledge의 운영 사례를 검토함으로써 국내 과학전문채널의 활성화에 유의미한 시사점을 제공하자 한다.

• 대한물리의학회지
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• 제7권3호
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• pp.283-291
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• 2012

Purpose : The purpose of this study was to identify education, attitudes and beliefs, interest and perceived role, self-efficacy and barriers to physical therapists' implementation of evidence-based practice for people with stroke. Methods : The participants were 120 physical therapists providing services to people with stroke in Gwang-ju. The questionnaire contained items to evaluate practitioner and organizational characteristics and perceptions of research considered to influence evidence-based practice. The prevalence of practitioner and organizational factors was estimated using percentages. Logistic regression was used to examine relationships between sociodemographic and practice characteristics and each practitioner factor. Results : 40% of respondents had learned the foundations of EBP in their academic preparation or received training in searching or appraising research literature. 88.3% agreed that research findings are useful. Self-efficacy ratings were 45%. Conclusion : Lack of education, negative perceptions about research and physical therapists' role in evidencebased practice, and low self-efficacy to perform EBP activities represent barriers to implementating EBP for people with stroke that can be addressed through continuing education.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.119-124
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• 1999

A selection methodology of liquid levelmeters, especially, level sensors in non-nuclear category, to be installed in nuclear energy facilities is developed using linguistic fuzzy approaches such as fully-linguistic and semi-linguistic methods. Depending on defuzzification techniques, the linguistic fuzzy methodology leads to either linguistic (exactly, fully-linguistic) or cardinal (i.e., semi-linguistic) evaluation. For the linguistic method, for each alternative, fuzzy preference index is converted to linguistic utility value by means of a similarity measure determining the degree of similarity between fuzzy index and linguistic ratings. For the cardinal method, the index is translated to cardinal overall utility value. According to these values, alternatives of interest are linguistically or numerically evaluated and a suitable alternative can be selected. Under given selection criteria, the suitable selections out of some liquid levelmeters for nuclear facilities are dealt with using the linguistic fuzzy methodology proposed. Then, linguistic fuzzy evaluation results are compared with qualitative result available in the literature. It is found that as to a suitable option the linguistic fuzzy selection is in agreement with the qualitative selection. Additionally, the comparative study shows that the fully-linguistic method using adequate scale system facilitates linguistic interpretation regarding evaluation results.

• 한국컴퓨터정보학회논문지
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• 제25권3호
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• pp.207-218
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• 2020

최근 온라인 리뷰의 증가와 분석 기술의 발달로 인해 온라인 리뷰 분석에 대한 관심과 수요가 지속적으로 증가하고 있다. 하지만 리뷰 분석을 다룬 기존의 연구는 동일한 어휘라도 각 어휘에 담긴 감정은 리뷰어에 따라 서로 다를 수 있다는 점을 반영하지 못했다는 한계를 갖는다. 따라서 본 연구에서는 고객의 등급에 따라 고객군을 분류하고, 각 고객군별로 리뷰 분석을 수행하여 그 차이를 분석한 결과를 제시하였다. 의류 전문 쇼핑몰인 'M'사의 리뷰에 대한 분석을 수행한 결과, 쇼핑몰 사용도가 높은 고객의 경우 가격적인 요소가, 쇼핑몰 사용도가 낮은 고객의 경우 쇼핑몰에 소개된 내용과 실제 제품의 일치 정도가 제품의 긍/부정 평가에 크게 영향을 미치는 것으로 파악되었다. 제안 방법론은 고객군별로 제품 평가에 중요하게 영향을 미치는 요소를 식별함으로써, 차별화된 마케팅 전략을 수립하는 데에 효과적으로 활용될 수 있을 것으로 기대한다.

• 한국화재소방학회논문지
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• 제25권4호
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• pp.1-7
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• 2011

최근 초고층 건축물의 방재분야에 대한 관심이 증가하고 있으며, 특히 화재발생 시 고층으로 인한 피난시간의 증가에 대비하여 건축물내의 화재전파를 최소로 억제하고자 노력하고 있다. 방화구획은 건축물에서 화재전파를 억제하는 대표적인 방법으로 내화성능이 있는 벽체와 방화문을 이용하여 화재발생 시 해당구획내에서 연소가 종료되거나 타 구획으로의 화재전파시간을 증가시킴으로써 피난시간을 확보하게 된다. 그러나 현행 건축법에는 초고층건축물을 고려치 않은 최대 2시간 내화성능만은 요구하고 있어 초고층 건축물용 방화벽의 개발에 걸림돌이 되고 있다. 따라서 본 연구에서는 내화벽체의 성능등급에 대하여 검토하였으며, 향후 초고층 건축물용 내화벽체 개발을 위하여 내화성능, 시공성, 사용성 등을 고려한 제품개발 방향을 제시하였다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제7권6호
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• pp.684-695
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• 2001

최근의 추천 시스템은 협력적 여과 시스템의 희박성과 초기 평가 문제를 해결하기 위하여 내용 기반 여과 시스템과 협력적 여과 시스템을 병합하는 방법을 사용한다. 협력적 여과 시스템은 부가적인 상품을 예측하기 위해 사용자의 선호도에 대한 데이타베이스를 사용한다. 내용 기반 여과 시스템은 상품의 속성과 사용자의 흥미를 대조함에 의해 아이템을 추천한다. 본 논문에서는 두 가지의 기술을 기계 학습 알고리즘에 응용하고 병합함으로써 사용자의 선호도를 발견하는 방법을 기술한다. 제안된 협력적 여과 방법에서는 유전자 알고리즘을 이용하여 Naive Bayes 분류자에 의해 분류된 아이템을 기반으로 사용자 군집을 생성하며 내용 여과 기법에서는 연관 피드백에 의해 사용자의 흥미를 추출함으로써 사용자의 프로파일을 생성한다. 제안된 방법은 웹문서에 대해 사용자가 평가한 데이타베이스에서 평가되며 기존의 방법보다 높은 성능을 나타냄을 보인다.

• 무역상무연구
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• 제61권
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• pp.273-302
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• 2014

Project finance ("PF") is a method of raising long-term debt financing based on lending against the cash flow generated by the project alone. Project finance is a nonrecourse or limited recourse financing structure against the sponsors(or the investors). The debt terms in a project finance are not based on the creditor's credit support or on the value of the assets of the project. Lenders rely on the future cash flow to be generated by the project for debt repayment and interest, rather than the value of the project or the credit ratings of the sponsors. The non-recourse or limited recourse financing usually prompt potential project finance lenders to assess carefully all possible risks that might arise in a project to ensure that those risks are mitigated and controlled. In this respect, project finance is a opposite financing method of corporate finance. Project finance has rapidly grown over the last 20 years due to the worldwide process of privatization of public sector and development of natural resources. Global project finance volume reached the record USD 406.5 billion in 2011. In 2012, however, Global project finance volume dropped 6% to USD 382.3 billion. Infrastructure overtook Energy to lead all sectors with USD 113.6 billion. It is generally recognized that there are more and higher risks in project finance compared with corporate finance. Project finance is exposed to commercial risks as well as political risks. The main commercial risks are completion risks, environmental risks, operating risks, input supply risks, revenue risks, etc, and the main political risks are currency convertibility and transfer risks, expropriation risks, war and civil disturbance risks, risks of breach of government concession agreement, etc. Completion risks include permits risks, risks relating to the EPC Contractor, construction cost overrun, delay in completion, inadequate performance on completion, etc.