• ETRI Journal
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• 제37권4호
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• pp.657-666
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• 2015

We propose a two-stage resource allocation algorithm for the high link utilization of an orthogonal frequency-division multiplexing passive optical network (OFDM-PON). An OFDM-PON is assumed to use a synchronous frame structure in supporting service differentiation. In distributing resources, the proposed algorithm first allocates a time window for each optical network unit (ONU), and then it arranges a subchannel, which is a group of subcarriers. This algorithm needs to satisfy two constraints. First, computations for the resource allocation should be done using a frame unit. Second, an ONU has to use a single subchannel to send upstream data for multiple services within a frame duration. We show through a computer simulation that the proposed algorithm improves the link utilization.

• 한국정보시스템학회지:정보시스템연구
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• 제16권1호
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• pp.159-178
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• 2007

As generalization of using PC and the Internet information technology (IT) users in organizations are not passive clients but active producers of information services. One of the reasons for the change of users' role is social interactions with other users and IT department staffs. That is, users can find and develop new functions and usefulness of IT, especially, Web-based ones through communication with other users or IT department staffs. The objective of this study is to investigate the relationship between IT department service quality and social interactions with other users. For this purpose, we suggest a research model based on adaptive structuration theory (AST), which is to explain the changes in social structure (rules and resources) of IT by social interactions, as well as service quality theory. Our model's exogenous variable is service quality which is a second-order factor consisting of reliability, responsiveness, assurance, and empathy. As endogenous variables, we adopt two variables for appropriateness of using IT, faithfulness of appropriation and consensus on appropriation. Finally, dependent variables of ow model are usefulness and ease of use which can be considered as attitude on IT as well as other variables for appropriateness. For empirical test our model is applied to users of groupware and ERP in organizations and analyzed by partial least square. In result, all hypotheses suggested in our model are supported statistically.

• Journal of Preventive Medicine and Public Health
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• 제26권1호
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• pp.86-95
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• 1993

To investigate perception and attitude toward Group Health Management and Service System for Small and Medium Industries, a survey using self-administered questionnaire was conducted to a part of industries in Inchon, at October 1992. Major dependent variables were perception, attitude, and practice related with Group Health Management and Service System; these variables were measured by 3-point Likert like scale consisted of 7, 5, and 5 items, respectively. Data were collected in 149 industries,72.7% out of 205. Perception nab slightly high, 1.25; attitude was some positive, 1.46; and practice was some passive,0.94. Major determinants of perception, attitude, and practice were sex and age of industry's health manager; perception influenced upon attitude, and perception and attitude had positive effect upon practice. To activate Group Health Management and Service System, it is necessary to develop education and promotion programs for industry's health managers of small and medium industries.

• ETRI Journal
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• 제28권5호
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• pp.583-592
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• 2006

Digital broadcasting technology has developed focusing on multi-channel/multi-media, high-definition quality, and mobility-support. Recently, there has been a clear trend toward bidirectional service with the convergence between broadcasting and communication. The broadcasting viewer is no longer simply a passive receptor but has also become an information generator. Currently, the digital multimedia broadcasting (DMB) specifications are the major standard for portable digital broadcasting and have been establishing the overall guidelines for bidirectional service using the MPEG-4 system. While detailed specifications for DMB systems are not well-established for bidirectional service yet, they share the basic concepts underlying the European Eureka-147 Digital Audio Broadcasting (DAB) system. This paper develops key scenarios for bidirectional service in DMB, describes the signal transaction of broadcasting and return channels, and demonstrates typical scenarios using binary format for scenes (BIFS) in the MPEG-4 system.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제4권4호
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• pp.161-168
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• 2015

클라우드 서비스가 다양해지고 그 수가 급격히 증가하면서 클라우드 서비스 사용자에게 적합한 서비스를 제공하기가 어려워지고 있다. 이러한 문제를 해결하기 위해 서비스 사용자와 제공자 사이에서 클라우드 서비스를 중개해주는 클라우드 서비스 브로커라는 개념이 제시되었다. 클라우드 서비스 브로커의 핵심적인 역할은 사용자의 요구사항에 적합한 서비스를 찾아주는 것이다. 그러나 현재 제시된 클라우드 서비스 브로커 대부분은 클라우드 서비스 전문가의 도움으로 사용자의 요구사항을 분석하는 수동적인 과정이 수행되고 있으며, 체계적으로 기능적, 비기능적 요구사항을 분석하는 과정이 미흡하다. 따라서 유사한 기능을 가지고 있는 클라우드 서비스 중 사용자의 요구사항의 중요도를 분석해서 가장 근접한 서비스의 선택을 지원해줄 수 있는 요구사항 분석 기법이 필요하다. 본 논문은 AHP(Analytic Hierarchy Process)의 쌍대비교법을 응용하여 클라우드 서비스에 대한 사용자의 요구사항을 분석하고 각 서비스의 명세에 따른 점수를 계산하여 그 결과에 따라 클라우드 서비스를 선택하는 방법을 제시한다.

• 대한전자공학회논문지TC
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• 제43권5호
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• pp.94-103
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• 2006

Ethernet Passive Optical Network (EPON)는 높은 효율성과 경제성 등의 장점을 바탕으로 초기 FTTH (Fiber To The Home) 구성을 위한 최적의 가입자망으로 많은 연구가 진행되고 있다. EPON의 상향 전송은 다수의 ONU (Optical Network Unit)가 단일 링크의 대역폭을 공유하기 때문에 동적으로 자원을 할당하는 자원 관리가 매우 중요하고, 자원 관리를 위한 다양한 동적 할당 방식이 제안되었다. EPON 시스템에서 QoS 지원을 위한 기존의 대역 할당 방식들은 SPQ (Strict Priority Queueing) 방식을 사용하였다. SPQ 방식은 높은 우선 순위를 가진 서비스 클래스에 대해서는 우선적 서비스를 보장해주기 때문에 하위 서비스 클래스에 대한 QoS 성능을 감소시키는 원인이 될 수 있다. 본 논문에서는 서비스 클래스 단위로 대역폭을 요청/할당 하는 Class Gated DBA 알고리즘을 제안한다. Class Gated DBA 알고리즘에서는 높은 우선 순위를 가진 서비스 클래스가 대역폭을 독점하는 현상을 방지하기 위해 각 서비스 클래스에 할당되는 최대 할당 대역폭을 설정한다. 그리고 높은 대역폭을 요구하는 ONU들에 대해서도 클래스 특성에 맞는 공평성 기반 대역 할당 알고리즘을 수행한다. 이와 같은 Class Gated DBA 알고리즘의 성능 분석을 위해 모의 실험을 수행하였고, 모의 실험을 통해 본 논문에서 제안하는 Class Gated DBA 알고리즘이 보다 좋은 QoS 성능을 보임과 동시에 사용자 사이에서 향상된 공평성을 제공할 수 있음을 확인할 수 있었다.

• 지역사회간호학회지
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• 제15권2호
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• pp.308-322
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• 2004

Purpose: 'The purpose of the present study was to understand students' experiences from their standpoint, to identify relevant variables and to examine into their relations by analyzing and describing what phenomenon 'nursing students' visiting ambulatory bathing service' is, what are the reasons for the phenomenon, and what interactions are in the phenomenon. Method: The subjects were thirteen students. Data were collected through in-depth interviews and analyzed by Strauss and Corbin's analysis method. Result: With regard to ambulatory bathing service, participants responded 'lack of education', 'inexperienced personal relations' and 'disappointment with recipients families'. They recognized 'burden' and 'compassion'. The intensity of generated 'burden' and 'compassion' was determined by volunteering persons, the degree of health care service, recipients' response and interaction of climate. When 'burden' and 'compassion' were generated, participants selected their own coping strategies. Strategies in the situation of 'burden' and 'compassion' were significantly influenced by 'burden' and 'compassion' and structural situation - 'mutual relation structure,' 'volunteers' capability,' 'the degree of volunteering guidance,' 'community participation,' 'recipients' environment,' 'information sharing,' 'special vehicle equipment' and 'economical burden.' Strategies include' service training,' 'receiving volunteering training,' 'preliminary service preparation,' 'volunteering.' 'connection to local medical center,' 'intention,' 'information sharing,' 'passive response to recipients' appreciation' and 'the understanding of publicity'. The results of selected 'burden' and 'compassion' are described with 'worthiness' and 'cohesion' as follows. Conclusion: This study is significantly meaningful in that it examined bathing service welfare in its initial stage. There are not much outcome from previous studies. However. it is meaningful that this study intended to develop theories on the nature of experiences and the relations among concepts derived from the visiting ambulatory bathing service process of nursing students. Professors who taught social volunteering in universities understood the experience of nursing students who did the visiting ambulatory bathing service. Consequently, professors will provide an effective instruction to enable these students to carry out visiting ambulatory bathing services efficiently in order to meet demands when they conduct the services. For the volunteering service activity in major-related fields among college students' social volunteering activities, they recognized the necessity of systematic education and preparation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.555-558
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• 2001

Carbonation of concrete decreases durability of RC structures due to failure of passive film of rebar. Therefore, expecting carbonation depth is a governing parameter of service life prediction for RC structures. This study attempt to estimate carbonation depth quantitatively by using equivalent effective diffusion coefficient of $CO_2$.

• 태양에너지
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• 제2권2호
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• pp.37-53
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• 1982

In general, glass has proven to be an effective glazing material, exhibiting extended service lifetime and high solar transmittance while remaining opaque to long wave thermal reradiation. Plastics, which possess higher solar transmittance than commercial glass, are lightweight and also cost competitive with glass. In this paper a survey of various glazing materials is presented, and the comparative analysis of their properties are perform ed in detail with special emphasis on double glazing materials, which can be adaptable to various passive solar systems.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.1055-1059
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• 2006

가입자망의 구현 형태의 하나인 EPON(Ethernet Passive Optical Network)에서의 대역할당 방식을 다룬다. EPON의 서비스 성능은 상향 트래픽을 어떻게 처리해주는 가에 영향을 많이 받는데, 본 논문에서는 4가지 등급으로 구분된 서비스 트래픽에 대한 QoS(Quality of Service)를 고려한 데이터 전송 서비스를 위한 알고리즘을 하나 제시하고, 이에 대한 성능 분석을 위해 시뮬레이션을 한다.