• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.2058-2074
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• 2017

Dense Heterogeneous Cellular Networks(HCNs) offer a promising approach to meet the target of 1000x increase in aggregate data rates in 5G wireless communication systems. However how to best utilize the available radio resources at densely deployed small cells remains an open problem as those small cells are typically unplanned. In this paper we focus on balancing loads across macro cells and small cells by offloading users to small cells, as well as dynamically switching off underutilized small cells. We propose a joint user association and base station(BS) sleep mangement(UA-BSM) scheme that proactively offloads users to a fraction of the densely deployed small cells. We propose a heuristic algorithm that iteratively solves the user association problem and puts BSs with low loads into sleep. An interference relation matrix(IRM) is constructed to help us identify the candidate BSs that can be put into sleep. User associations are then aggregated to selected small cells that remain active. Simulation results show that our proposed approach achieves load balancing across macro and small cells and reduces the number of active BSs. Numerical results show user signal to interference ratio(SINR) can be improved by small cell sleep control.

• Journal of Ecology and Environment
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• 제44권2호
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• pp.106-114
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• 2020

Background: Determining patterns of habitat use is key to understanding of animal ecology. Approximately 1% of bird species use brood parasitism for their breeding strategy, in which they exploit other species' (hosts) parental care by laying eggs in their nests. Brood parasitism may complicate the habitat requirement of brood parasites because they need habitats that support both their host and their own conditions for breeding. Brood parasitism, through changes in reproductive roles of sex or individual, may further diversify habitat use patterns among individuals. However, patterns of habitat use in avian brood parasites have rarely been characterized. In this study, we categorized the habitat preference of a population of brood parasitic lesser cuckoos (Cuculus poliocephalus) breeding on Jeju Island, Korea. By using compositional analyses together with radio-tracking and land cover data, we determined patterns of habitat use and their sexual and diurnal differences. Results: We found that the lesser cuckoo had a relatively large home range and its overall habitat composition (the second-order selection) was similar to those of the study area; open areas such as the field and grassland habitats accounted for 80% of the home range. Nonetheless, their habitat, comprised of 2.54 different habitats per hectare, could be characterized as a mosaic. We also found sexual differences in habitat composition and selection in the core-use area of home ranges (third-order selection). In particular, the forest habitat was preferentially utilized by females, while underutilized by males. However, there was no diurnal change in the pattern of habitat use. Both sexes preferred field habitats at the second-order selection. At the third-order selection, males preferred field habitats followed by grasslands and females preferred grasslands followed by forest habitats. Conclusions: We suggest that the field and grassland habitats represent the two most important areas for the lesser cuckoo on Jeju Island. Nevertheless, this study shows that habitat preference may differ between sexes, likely due to differences in sex roles, sex-based energy demands, and potential sexual conflict.

• 전기학회논문지
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• 제65권4호
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• pp.555-560
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• 2016

Recently, many countries have placed great attention on energy security and climate changes. Governments are promoting the construction of renewable energy projects with regulatory support in Korea. Despite an increasing penetration of renewable resources, however, the photovoltaic and wind power are underutilized due to the endemic problems such as difficulties of output control and intermittent output. The Energy Storage System (ESS) is proposed as a good solution for solving the problems and has been studied in both the private business and the government. However, because of inefficient aspects, the research has been carried out for improving high costs and a small capacity. In addition, the ESS is currently installed for using only one purpose which is frequency regulation or transmission congestion relief such that has an economic limitation. Therefore, methods which are becoming economically justifiable to increase the penetration of the ESS is required. Thus, this paper presents in terms of operation efficiency to improve economic feasibility of the ESS currently used. mainly, there are two aspects for the operation efficiency. Firstly, it is intended to improve the utilization rate through a process that can utilize the ESS for various purposes. It is necessary to be able to use for other purposes by classifying and clustering for increasing the efficiency of availability. The clustering method is proposed to conduct the grouping the ESS. Especially, it is proposed to utilize ESS for frequency regulation service which is the one of ancillary services in the power system. Through case studies, it is confirmed to secure the necessary resources by clustering small size ESS.

• 환경정책연구
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• 제9권4호
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• pp.103-123
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• 2010

오하이주에 위치한 클리블랜드 시(city of Cleveland)는 과거 자동차 공업을 중심으로 한 공업 중심 도시에서 생명공학 중심 도시로의 변화를 꾀하고 있다. 따라서 과거 공업부지(브라운필드)의 재사용 및 재개발이 클리블랜드 시의 환경정책에 큰 비중을 차지하게 되었다. 클리블랜드 시를 포함하고 있는 쿠야호가 카운티(Cuyahoga County)는 브라운 필드 재개발에 민간 영역의 투자를 유도하고자 보조금을 지급해 왔다. 카운티 정부의 브라운 필드 재개발 보조금 (Brownfield Redevelopment Fund)은 지난 2십년간 많은 민간 부분의 투자를 유도하는 데 성공하였다. 본 연구는 브라 운필드 보조금의 효과를 측정하고자 외부효과를 측정하는 전통적인 방법인 헤도닉 모형(Hedonic Model)을 이용하여 쿠야호가 카운티의 브라운필드 보조금이 주변 주택 판매가격 상승에 미치는 영향을 분석하였다.

• 한국콘텐츠학회논문지
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• 제12권12호
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• pp.823-833
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• 2012

방송 제작현장에서 이뤄지는 일터학습은 예비 방송 인력의 전문성 향상을 위해 필요한 교육과정이지만 대학 커리큘럼에 적극적으로 활용되지 못하고 있다. 이에 본 연구는 언론 관련 학과 학생들이 경험한 일터학습 사례를 제시하고 일터학습이 지닌 장단점과 효과 및 향후 방송 실무교육의 나아갈 방향을 살피고자 하였다. 14명의 대학생들을 대상으로 포커스그룹 토론을 통해 도출된 연구 결과는 다음과 같다. 첫째, 대학생들은 기존의 대학 실무교육이 제공하지 못하는 구체적인 현실 상황을 일터학습에서 경험한 것으로 파악되었다. 이로써 학생들은 현장 적응력과 콘텐츠 생산자로서의 인식을 갖추게 되었으나 생존경쟁이 심화되고 있는 방송산업계 현실 앞에서 직업 선택에 다소 혼란을 느끼게 된 것으로 나타났다. 둘째, 대학생들은 일터에서 시행착오나 실수, 피드백, 선의의 경쟁, 모방을 통해 자발적으로 학습하는 무형식학습을 경험하였으며 일터학습 결과 인터뷰 요령, 촬영 및 편집, 틀짓기, 사회적 대인관계 영역 등에서 암묵지를 형성한 것으로 나타났다. 이러한 분석 결과는 향후 방송 실무 강의자들이 일터학습에 보다 관심을 갖고 이를 적극적으로 활용할 필요성을 보여주는 것이다.

• 한국문헌정보학회지
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• 제27권
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• pp.265-289
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• 1994

Databases publicly available for online searching permit both citation and subject searching, however, subject searching has dominated the online search environment. Despite the power of citation searching, it may be underutilized This study explored the relationship between the number of cited references used in a citation search and information retrieval effectiveness, a relatively unstudied phenomenon. Three articles in the library and information science literature were chosen to represent sample questions. Cited reference searches were conducted for each article and each of its references. All searches were conducted in Social Scisearch and Scisearch on DIALOG. Relevance judgments on the retrieved citations were obtained from the authors of the original articles. This research focused on analyzing, in terms of information retrieval effectiveness, the overlap among postings sets retrieved by various combinations of cited references. The findings from the three case studies clearly showed that the more cited references used for the citation search, the better the performance, in terms of retrieving more relevant documents, up to a point of diminishing retums. In addition, generally the overall level of overlap among relevant documents sets was found to be low. Therefore, if only some of the cited references among many candidates are used for a citation search, a significant proportion of relevant documents may be missed. The analysis of the characteristics of cited references provided the ways to predict which cited refereces would be useful to improve information retrieval. The findings of this comprehensive exploratory study are of interest for both theoretical and practical reasons. They contribute to the development of a theoretical model for the effective use of the citation search. This model might also be implemented in operational online systems. In addition, the findings potentially will help online searchers improve their search strategies using the citation search so that they can better achieve their information retrieval goals: the retrieval of items relevant to a given question and the suppression of nonrelevant items.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1791-1796
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• 2014

Background: Colorectal cancer (CRC) is a leading cause of cancer death among Vietnamese Americans, yet screening remains underutilized. We investigated the effectiveness of a culturally tailored DVD intervention in promoting CRC screening among unscreened Vietnamese Americans age 50 and over. Materials and Methods: Using a community-based participatory research approach, we conducted a trial comparing twenty-eight subjects who received a mailed DVD in Vietnamese, with twenty-eight subjects who received a mailed brochure in Vietnamese. Subjects completed telephone surveys at baseline, One-month, and one-year. The primary outcome was receipt of screening. Secondary measures were participants' knowledge, attitudes, and beliefs about CRC screening. Two focus groups explored the intervention's acceptability and effectiveness. Results: At one year, CRC screening rates of 57.1% and 42.9% were observed in experimental and control group respectively (p=0.42), Subjects in both groups showed increased knowledge about CRC after one month. Focus group findings revealed that the DVD was an effective method of communicating information and would help promote screening. Conclusions: The findings suggest that culturally tailored, linguistically appropriate content is more important than the type of media used. This relatively low intensity, low cost intervention utilizing a DVD can be another useful method for outreach to the often hard-to-reach unscreened population.

• Preventive Nutrition and Food Science
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• 제19권3호
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• pp.227-233
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• 2014

The discovery of bioactive compounds in foods has changed the dietary lifestyle of many people. Cyperus esculentus (tigernut) is highly underutilized in Africa, yet tigernut extract is highly profitable in Europe. This study aims to add value to tigernut extract by revealing its health benefits and food value. In this study, tigernut tubers were germinated or roasted and the extracts were combined with Moringa oleifera extract (MOE) or Hibiscus sabdariffa extract (HSE) and spiced with ginger to produce functional drinks. The drinks were evaluated for physicochemical characteristics, sensory parameters, and antioxidant potentials. The total phenolic content of each beverage was measured by the Folin-Ciocalteu method, and the antioxidant activity of each beverage was determined by the 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid assays. The beverages from the germinated tigernut extracts had the highest titratable acidity and the lowest pH, while beverages containing the roasted tigernut extract had the highest $^{\circ}Brix$. Germination and roasting significantly enhanced the total phenolic content of the drinks. The beverage containing HSE and germinated tigernut extract had a total phenolic content of 45.67 mg/100 mL gallic acid equivalents, which was significantly higher than the total phenolic content of all other samples. The DPPH inhibition activity of the beverages prepared with germinated tigernut extracts was significantly higher than the DPPH inhibition activity of the beverages prepared with fresh tigernut extract. The taste and overall acceptability of drinks containing the roasted tigernut extract were preferred, while the color and appearance of drinks with the germinated samples were preferred. Roasting or germinating tigernuts before extraction and addition of MOE or HSE extracts is another way to add value and enhance the utilization of tigernuts.

• Journal of Biosystems Engineering
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• 제41권3호
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• pp.193-200
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• 2016

Purpose: New low-cost oilseeds are needed to meet an ever-increasing demand for oil for food, pharmaceutical, and industrial applications. African oil bean seed is a tropical crop that is underutilized and has high oil yields, but there have been no studies conducted on its mechanical oil expression up to now. The objective of this work was to investigate the effect of moisture content and seed dimensions on mechanical oil expression from the seeds. Methods: Fresh oil bean seeds were procured, de-hulled, and cleaned. Initial seed moisture content, obtained in accordance with the ASAE standard, was 12% dry basis (db). The seeds were further conditioned by dehydration and rehydration prior to oil expression to obtain four other moisture levels of 8, 10, 14, and 16% db. The major diameter of the seeds was measured using digital vernier calipers, and the seeds were classified into size dimensions (< 40, 41-45, 46-50, 51-55, and > 55 mm). The oil yield and expression efficiency were obtained in accordance with standard evaluation methods. Results: The highest oil yield and expression efficiency (47.74% and 78.96%, respectively) were obtained for a moisture content of 8% db and seed dimensions of < 40 mm, while the lowest oil yield and expression efficiency (41.35% and 68.28%, respectively) were obtained for a moisture content of 14% db and seed dimensions between 51-55 mm. A mathematical model was developed to predict oil yield for known moisture content and seed dimensions, with a coefficient of determination $R^2$ of 95% and the confidence level of the predictive model of 84.17%. The probability of prediction F ratio showed that moisture content influence was more significant than seed dimensions. Conclusions: The higher the moisture content and larger the seed dimensions, the lower the oil yield from African oil bean seeds.

• 정보관리연구
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• 제35권2호
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• pp.1-40
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• 2004

학위논문은 석박사 과정의 학생들이 학위를 취득할 목적으로 자신의 전공분야와 특정 관점에서 조사 연구한 결과를 제출한 독창성이 높은 연구자료를 말한다. 그러나 학위논문은 상업출판사에서 발간하지 않기 때문에 대다수 도서관도 책자형태로 확보할 수 없다. 이에 따른 실물의 즉시적 이용가능성 및 내용정보의 부재현상은 모든 국가에서 학위논문의 활용도가 극히 낮을 수밖에 없는 요인으로 작용하고 있다. 이러한 상황에 주목하여 본 연구는 학위논문의 국제적 유통현황을 개관하고 국내의 관리시스템을 조사 분석하였다. 그리고 본 연구의 결과는 후속의 최종과제인 국내 학위논문의 표준관리모형을 개발하는데 활용될 것이다.