• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.152-155
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• 1993

Protective Relay in power system play a prominent part in minimizing power delivery interruptions and help to get a fast and secure restoration when a failure occurs. In order to meet the higher functional requirements in power system, the performance tests on response characteristic of protective relay is essential to ensure reliability. The purpose of this study is as follows: In order to evaluate performance of protective relay, it is intended to develop performance of digital protective relay simulator which is composed of digital protective relay part, behaviour analysis part, waveform generation part and simulation program to simulate pour system in detail.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.744-747
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• 2004

인터넷은 전 세계를 연결하는 매체로서, 그 사용자가 매년 폭발적으로 증가하고 있다. 이러한 인터넷 사용자간의 자료 교환 수단으로서 전자우편은 표준이라 말할 수 있을 만큼 많이 사용되고 있다. 하지만 이러한 전자우편에도 많은 문제가 존재한다. 기존의 전자우편은 간단한 방법으로 내용을 열람하거나 변조할 수 있어 중요한 정보나 사생활 노출의 위험에서 벗어날 수 없다. 따라서 암호학적으로 강력한 전자우편 시스템의 개발이 시급하다. 본 논문에서는 기본적인 정보보호 서비스 외에 기존의 전자우편 시스템에서는 제공되지 않는 배달 증명 및 내용 증명 기능을 제공하여 자바 암호 API를 사용하여 안전한 키 교환이 가능하도록 하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.60-70
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• 2020

The outfitting design of ships and offshore structures is mainly undertaken in a restricted space. Pipes occupying a large portion of outfitting design are normally manufactured outside the shipyard. This complicated manufacturing process results in frequent delivery delays. Inevitable design modifications and material changes have also resulted in inefficient pipe installation works. In this study, an algorithm is proposed to systematically determine the pipe installation sequence. An accurate and fast algorithm to identify the geometric relationship of piping materials is presented. To improve the calculation efficiency, the interference is gradually examined from simplified to complicated shapes. It is demonstrated that the calculation efficiency is significantly improved with successive geometric operations such as back-face culling and use of bounding boxes. After the final installation sequence is determined, the entire installation process is visualized in a virtual reality environment so that the process can be rendered and understood for a full-scale model.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.440-448
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• 2009

Concurrent construction (or overlapping) is an alternative project delivery process to reduce time-tomarket such that the owner can get higher profits; the increased profits due to shortened project duration would exceed the loss of profits from the increased cost, if any. For more effective concurrent construction, a new conceptual framework for concurrent construction planning is suggested. With multiple work methods available in each activity, the performance of overlapping between two activities in terms of cost is affected by the compatibility between work methods selected and the benefit to the project owner is determined by internal rate of return (RoR). The impact of the compatibility between work methods and the conceptual framework are explained by a hypothetical case study.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.371-375
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• 2015

Design-Build (DB) has gained in popularity in roadway projects due to its defining advantage to improve communication and fast-track project delivery. However, very little is known about the impact of change order frequency and occurrence timing pertaining to DB projects. The study analyzes their impacts on project time and cost performance by conducting a rigorous numerical analysis drawing on 530 3R (rehabilitation, reconstruction, and resurfacing) projects completed between 2002 and 2011 in Florida by using a multiple linear regression. The results indicate that DB outperformed Design-Bid-Build in project cost as well as time. Critically, the regression analysis signifies that earlier change order occurrence caused more unfavorable impacts on schedule and cost. The proposed analyses and models will lead to the improved ability of agencies to quickly and more reliably estimate the potential change order impacts on schedule and cost.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제2권6호
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• pp.265-278
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• 2013

최근 다양한 무선 통신기술이 발전됨에 따라 네트워크 자원을 효율적으로 사용하기 위하여 모바일 멀티캐스트 기법의 중요성이 부각되고 있다. 기존에는 멀티캐스트 서비스를 위한 네트워크 전달 비용적 측면과 멀티캐스트 핸드오버 지연 최소화에 중점을 두고 모바일 IP기반의 다양한 멀티캐스팅 기법들이 제안되었다. 그러나 호스트 기반의 이동성 관리 기술인 MIPv6(Mobile IPv6)를 이용한 기법들은 근본적으로 핸드오버의 지연과 터널 컨버전스 문제를 해결하기 어렵다. 이러한 문제점을 해결하기 위해서 네트워크 기반의 이동성 관리 기술인 PMIPv6(Proxy Mobile IPv6)를 표준화하였다. PMIPv6는 MIPv6에 비해서 성능이 향상되었지만 여전히 핸드오버 지연과 터널 컨버전스 등의 문제를 가지고 있다. 본 논문에서는 이러한 한계를 해결하기 위하여 PMIPv6 네트워크에서 멀티캐스팅을 지원하는 저비용의 빠른 이동성관리를 위한 LFH(Low-Cost and Fast Handoff) 기법을 제안한다. 복잡한 멀티캐스트 라우팅 프로토콜과 멀티캐스트 구성원 메시지의 상호작용을 줄이기 위해 간소화된 MLD(Multicast Listener Discovery) 프록시 기능을 구현하고 MLD 기능을 수정한다. 그리고 LMA(Local Mobility Anchor) 도메인 내에서의 멀티캐스트 핸드오버 절차와 도메인 간에서의 멀티캐스트 핸드오버 절차에 TCR(Tunnel Combination and Reconstruction) 알고리즘을 사용하여 터널 컨버전스 문제를 해결한다. 그 결과 LFH 기법의 성능이 다른 멀티캐스트 방식과 비교하여 멀티캐스트 중단시간을 줄여주어 더 적은 비용이 든다는 것을 보여준다.

• 산경연구논집
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• 제9권12호
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• pp.63-72
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• 2018

Purpose - In this study, it is classified the service quality dimension of mobile shopping app using Kano model. In addition, it is evaluated quality factors suitable for strategic management from the viewpoint of service provider through mobile application through binary dimension analysis. Research design, data, and methodology - In this study, seven quality dimensions such as information quality, reliability, immediacy, convenience, design, security and customer service were derived through related studies to make binary shopping quality app quality measurement. 37 sub-variables were set by each quality dimensions. Each questionnaire was composed of positive and negative items like Kano's proposed method, and the satisfaction coefficient suggested by Timko(1993) was examined to understand the influence of each factors on customer satisfaction. Results - As a result of research, shopping app users perceived unity quality factor in most items of service quality dimension such as information quality, reliability, immediacy, convenience and customer service. In addition, the satisfaction coefficient showed a good impression, quick response of the result, fast delivery, and the unsatisfactory coefficient showed more interest in personal information such as payment method safety, and transaction security. As a result of research, shopping app users perceived unity quality factor in most items of service quality dimension such as information quality, reliability, immediacy, convenience and customer service. And, in information quality, the information overload was classified as an apathetic quality component, while the related information provision belonged to an attractive quality component. In reliability quality, customized service provision was classified as an attractive quality component. In instant connectivity, the quality of the connection during transport was classified as an attractive quality component. In convenience quality, access to product information was classified as a one-way quality component. All components of designs quality were classified as attractive quality components, and in security quality, all of their components were all classified as one quality component. Lastly, in customer service, they components were all classified as a single quality component. In addition, the satisfaction coefficient showed a good impression, quick response of the result, fast delivery, and the unsatisfactory coefficient showed more interest in personal information such as payment method safety, and transaction security. Conclusion - In the online service environment, which is difficult to differentiate in terms of upward upgrading only by technological implementation and function, the results of this study can be suggested as a differentiating factor for major channels with customers rather than improve the brand image.

• Macromolecular Research
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• 제17권12호
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• pp.1025-1031
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• 2009

Several kinds of biodegradable hydrogels were prepared via in situ photopolymerization of Pluronic F127/poly($\varepsilon$-caprolactone) macromer and acrylic acid (AA) comonomer in aqueous medium. The swelling kinetics measurements showed that the resultant hydrogels exhibited both thermo- and pH-sensitive behaviors, and that this stimuli-responsiveness underwent a fast reversible process. With increasing pH of the local buffer solutions, the pH sensitivity of the hydrogels was increased, while the temperature sensitivity was decreased. In vitro hydrolytic degradation in the buffer solution (pH 7.4, $37^{\circ}C$), the degradation rate of the hydrogels was greatly improved due to the introduction of the AA comonomer. The in vitro release profiles of bovine serum albumin (BSA) in-situ embedded into the hydrogels were also investigated: the release mechanism of BSA based on the Peppas equation was followed Case II diffusion. Such biodegradable dual-sensitive hydrogel materials may have more advantages as a potentially interesting platform for smart drug delivery carriers and tissue engineering scaffolds.

• 대한의용생체공학회:의공학회지
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• 제39권1호
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• pp.30-35
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• 2018

Conventional drug delivery methods mainly include subcutaneous injection and oral administration. Subcutaneous injection has the advantages of delivering the correct concentration, but it might cause pain and trauma to patients. Although oral administrations do not accompany pain as the subcutaneous injection, unexpected side effects may occur because they undergo digestion process and it is not easy for many drugs to be exposed to targeted sites with proper concentration. While dissolving microneedles have been extensively studied to overcome the limitations of conventional subcutaneous injection, the effects on microneedle shapes for drug release have not been fully explored. In this study, the characteristics of hyaluronic acid microneedles for cone and quadrangular pyramidal shapes were examined by the size, volume, contact surface area, skin permeability, and dissolution rate. As a result, the cone shapes of hyaluronic acid microneedles had high skin permeability, and the quadrangular pyramid of shapes hyaluronic acid microneedles showed a fast dissolution rate, given by the large contact area on the skin. Based on the results, we could confirm that the shape of a dissolving microneedles can affect skin permeability and the drug delivery rate.

• 한국통신학회논문지
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• 제37권7C호
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• pp.627-636
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• 2012

최근에 XML은 가독성과 확장성이란 장점 때문에 IPTV나 디지털방송 서비스 분야에서 서비스나 콘텐츠 정보 표현 및 검색을 위한 기술로 많이 사용되고 있다. 특히 TV-Anytime에서 정의한 스키마나 전송 프로토콜을 기본 규격으로 채택하고 필요한 기능을 수용하기 위하여 규격을 확장하는 경향을 보이고 있다. 그러한 장점에도 불구하고 XML은 텍스트 기반으로 정보를 표현함으로써 정보의 양이 커진다는 문제가 존재하고 이를 위하여 다양한 인코딩 방식이 제공되고 있다. 그러나 전송과정에서 문서를 독립된 조각으로 단편화하여 블록단위로 캡슐화 하는 과정을 거치면서 인코딩 효율이 급격하게 떨어지게 되는 문제가 발생한다. 본 논문에서는 XML 문서를 캡슐화하는 과정에서 단편화를 통해 감소되는 인코딩 효율을 보완할 수 있는 블록 단위의 문자열 테이블 방식을 제안하고 실험을 통한 성능 분석을 제공하였다.