• 한국문헌정보학회지
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• 제22권
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• pp.361-396
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• 1992

The purpose of this study is to verify the correlations between the amount of the online searcher's search experience and their search effect. In order to achieve this purpose, the 28 online searchers working at the chosen libraries and information centers have participated in the study as subjects. The subjects have been classified into the two types of cognitive style by Group Embedded Figure Test. As the result of the GEFT, two groups have been identified: the 15 Field Independance ( FI ) searchers and the 13 Field Dependance ( FD ) searchers. The subject's search experience consists of the 3 elements: disciplinary, training, and working experience. In order to get the data of these empirical elements, a questionnaire have been sent to the 28 subjects. An online searching request form prepared by a practical user was sent to all subjects, who conducted searches of the oversea databases through Dialog to retrieve what was requested. The resultant outcomes were collected and sent back to the user to evaluate relevance and pertinence of the search effect by the individual. In this study, the search effect has been divide into relevance and pertinence. The relevance has been then subdivided into the 3 elements : the number of the relevant documents, recall ratio, and the cost per a relevant document. The relevance has been subdivided into the 3 elements: the number of the pertinent documents, utility ratio, and the cost per a pertinent document. The correlations between the 3 elements of the subject's experience and the 6 elements of the search effect has been analysed in the FI and in the FD searchers separately. At the standard of the 0.01 significance level, findings and conclusions made in the study are summarised as follows : 1. There are strong correlations between the amount of training and the recall ratio, the number of the pertinent documents, and the utility ratio on the part of FI searchers. 2. There are strong correlations between the amount of working experience and the number of the relevant documents, the recall ratio on the part of FD searchers. However, there is also a significant converse correlation between the amount of working experience and the search cost per a pertinent document on the part of FD searchers. 3. The amount of working experience has stronger correlations with the number of the pertinent documents and the utility ratio on the part of FD searchers than the amount of training. 4. There is a strong correlation between the amount of training and the pertinence on both part of FI and FD searchers.

• Journal of Plant Biology
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• 제22권3호
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• pp.63-69
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• 1979

The plant growth and net production, the nitrogen uptake and recycling, the nitrogen mobility and allocation to each organ, and the nitrogen utility from the Italian rye grass field during the population development were analyzed in comparison with different clipping treatments. The maximum dry matter standing crop and nitrogen quantity of harvest increased significantly, however, the annual amounts of dry matter and nitrogen assimilation showed little variations with increasing clipping frequencies. Plants treated with frequent clippings allocated relatively more nitrogen to leaves and less to roots during the experimental period. The amount of recycling of nitrogen decreased considerably due to frequent clippings. The annual averages of nitrogen utility indices changed in inverse relation to the nitrogen availability; such as 63, 58, 44 and 35 for C, A, M and J plots, respectively.

• 전력전자학회논문지
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• 제18권1호
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• pp.103-109
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• 2013

The conventional LCL filter design method of the utility interactive inverter considers only harmonics attenuation of the current injected to the grid. However, in case of utility-interactive inverter with critical load the voltage quality of the critical load should also be considered for LCL filter design. Also, considering cost and volume of LCL filters. it is important to have minimum values of inductance and capacitance as far as the harmonic standards are satisfied. In this paper a LCL filter design method is proposed to satisfy not only the harmonic standards of the grid current during the grid-connected mode but the voltage quality of the critical load during grid-connected mode and stand-alone mode. With the proposed method optimized values of LCL filters could be obtained by applying weighting factor to voltage ripple across the critical load, inductor volume, amount of reactive current and system bandwidth.

• 전력전자학회논문지
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• 제12권1호
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• pp.81-88
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• 2007

본 논문에서는 연료전지를 이용한 가정용 발전 시스템의 계통 연계를 위한 새로운 단상 인버터 시스템을 제안한다. 제안한 인버터는 계통연계 운전과 독립 운전이 모두 가능하고 두 운전사이의 모드전환이 자동으로 이루어지며 전환시 최소의 과도상태를 갖는다. 제안한 제어방식은 정상상태 오차가 거의 없고 양호한 과도상태 응답특성을 가진다. 또한 연산량과 센서수가 적고 구조가 간단하여 저가격의 고정소수점 DSP로도 구현이 가능한 특징이 있다. 제안한 계통연계형 인버터의 제어기에 관하여 기술하고 모의실험 및 실험에 의하여 그 타당성을 입증한다.

• 한국산학기술학회논문지
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• 제17권7호
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• pp.31-41
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• 2016

본 연구에서는 발전소 응축기를 모사할 수 있는 프로그램을 개발하고 발전소 응축기에 전열 촉진관 적용시 얻을 수 있는 여러 효과에 대하여 검토하였다. 평활관을 촉진관으로 교체한다면, 전열량의 증가에 따른 수증기 응축 온도가 내려가게 되므로 발전소의 효율이 증가하게 된다. 따라서 촉진관을 사용하면 기존 설비를 그대로 두고서도 상당량의 전력 여유도를 확보할 수 있다. 고려된 전열 촉진관은 외경 22.2 mm 티타늄 재질의 코류게이트 관, 리브 조도 낮은 핀관, 삼차원 조도 낮은 핀관이다. 내측 조도의 경우 최적 조도 높이가 존재하였다. 또한 삼차원 조도 낮은 핀관이 다른 두 형상보다 우수하게 나타났다. 삼차원 조도의 경우 원주 방향으로 인접한 딤플 사이에서 흐름 방향으로 선회류가 유발되고 이 선회류에 의하여 열전달이 촉진되기 때문이다. 600 MW 발전소 응축기에 전열 촉진관을 적용하면 0.5 MW~1.3 MW 가량의 추가 전력을 생산할 수 있다. 또한 냉각수 온도가 올라가면 추가 전력도 증가한다. 실제로 발전소 응축기에 적용하기 위해서는 열 성능 외에도 화울링, 부식, 기계적 특성 등이 고려되어야 한다.

• Korean Chemical Engineering Research
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• 제55권1호
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• pp.54-59
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• 2017

ABS 중합공정 중 잔류 모노머 회수 공정의 유틸리티 사용량 절감을 위한 공정의 개선을 수행하였다. ABS 폴리머 생산 과정 중 잔류 모노머 회수 공정은 제품의 품질 향상을 위해 반드시 필요하다. 잔류 모노머의 회수를 위한 다양한 방식이 있으나, 본 연구에서 대상으로 한 것은 스팀 스트리핑 공정이다. 기존의 스팀 스트리핑은 많은 양의 스팀과 냉각수가 사용되고 있으나, 본 연구를 통해 유틸리티 사용을 절감하는 새로운 방안을 찾고자 하였다. 스트리핑 후 모노머와 함께 배출되는 스팀의 잠열을 진공상태의 수증기로 회수하고, 압축으로 온도를 상승시켜 스트리핑 스팀으로 재사용하도록 함으로써 스팀의 사용을 획기적으로 절감하였다. 또한 모노머 최종 회수 과정에서 발생되는 물을 모노머 응축에 냉각수로 활용함으로써 용수에 대한 사용량도 감소 시킬 수 있었다.

• 한국정보처리학회논문지
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• 제7권6호
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• pp.1766-1777
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• 2000

In multimedia new service on the internet, there are problems such as server overload, network congestion and initial latency. To overcome these problems, we propose a proxy push-caching scheme that stores a portion of continuous media stream or entire stream, and a transmission scheme of NOD continuous media, RTP-RR and RTP-nR to exploit push-caching scheme. With the proposed push-caching scheme, NOD server pushes fixed portion of stream to a proxy when new data is generated, and the cached size of each stream changes dynamically according to the caching utility value of each stream. As a result, the initial latency of client side could be reduced and the amount of data transmitted fro ma proxy server to client could be increased. Moreover, we estimate a caching utility value of each stream using correlation between disk space occupied by the stream and the amount of data stream requested by client. And we applied the caching utility value ot replacement policies. The performance of the proxy push-caching and continuous media transmission schemes proposed were compared with other schemes using simulations. In the simulation, these schemes show better results than other schemes in terms of BHR (Byte Hit Rate), initial latency, the number of replacement and packet loss rate.

• 대한한의진단학회지
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• 제16권3호
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• pp.23-32
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• 2012

Objectives: The objective of this study is to investigate and valuate currently provided database management systems (DBMS) of traditional Korean medical knowledge. Methods: We searched DBMS on the web and smart device application markets (Apple App Store and Google Play Store). Key words for searching were 'traditional medicine', 'acupuncture', 'moxibustion', 'herbal medicine', and '한의학'. We looked into each DBMS to find out its scopes and limits, and each was valuated according to its functionality, accessibility, and utility. Results: 186 DBMS of traditional Korean medical knowledge were investigated and 91% of them were applications for smart devices. Almost all DBMS provided acupuncture and herb information, and a small amount of DMBS provided prescription and research paper information. Functionality, accessibility, and utility valuation were performed by using scoring system from 0 to 2. Mean values of functionality, accessibility, and utility were 0.86, 1.29, and 1.09. Conclusions: On the whole, high accessibility and low functionality were found, and various data-calculating functions were not implemented. Further researches and developments about traditional Korean medical knowledge DBMS are necessary to provide correct traditional Korean medical information and to support the studies about Korean medicine.

• 정보처리학회논문지B
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• 제16B권3호
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• pp.225-232
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• 2009

동명이인의 저자를 구분하는 것은 웹에서 문서 색인과 검색의 성능을 향상시킨다. 동명이인의 저자 구분은 웹사이트 상에서 같은 이름을 갖는 여러 명의 사람이 존재했을 때 야기되는 여러 가지 문제점을 해결한다. 본 논문은 동명이인의 저자 구분을 위해 개념망 기반의 카테고리 유틸리티를 제안한다. 따라서 본 논문에서는 학술회의 웹 사이트를 대상으로 제안하고자 하는 방법을 설명한다. 제안된 방법은 저자가 가지고 있는 다양한 속성(제목, 요약, 공동저자, 소속)을 반영한 저자 온톨로지와 개념망을 활용한다. 저자 온톨로지는 OWL API와 휴리스틱한 방법을 사용하여 반자동으로 구축 되었다. 저자명 모호성 해결은 개념망 기반 카테고리 유틸리티를 사용하여 저자 온톨로지 내에 존재하는 동명이인 저자(Candidate Authors)들로부터 해당 논문에 관련된 정확한 저자를 결정한다. 카테고리 유틸리티는 각각의 저자간의 intra-class 유사성 와 inter-class 비유사성을 기본적인 개념으로 하는 평가 함수다. 이에 비해 개념망 기반 카테고리 유틸리티는 모호성 해결을 위해 개념망이 갖는 개념 정보를 추가로 활용한다. 실험 결과를 분석한 결과 개념망 기반 카테고리 유틸리티가 일반적인 카테고리 유틸리티에 비교해서, 저자명 모호성 해결에 있어서 10% 정도 우수한 성능을 보였으며, 전체적으로 98%의 정확도를 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4848-4863
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• 2016

The explosive wireless data service requirement accompanied with carbon dioxide emission and consumption of traditional energy has put pressure on both industria and academia. Wireless networks powered with the uneven and intermittent generated renewable energy have been widely researched and lead to a new research paradigm called green communication. In this paper, we comprehensively consider the total generated renewable energy, QoS requirement and channel quality, then propose a utility based renewable energy allocation policy. The utility here means the satisfaction degree of users with a certain amount allocated renewable energy. The energy allocation problem is formulated as a constraint optimization problem and a heuristic algorithm with low complexity is derived to solve the raised problem. Numerical results show that the renewable energy allocation policy is applicable not only to soft QoS, but also to hard QoS and best effort QoS. When the renewable energy is very scarce, only users with good channel quality can achieve allocated energy.