• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.6
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• pp.635-641
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• 2011

In ultrasonic testing of dissimilar metal welds, application of phased array technique in terms of incident beam focusing is not easy because of complicated material structures formed during the multi-pass welding process. Time reversal(TR) techniques can overcome some limitations of phased array since they are self-focusing that does not depend on the geometrical and physical properties of testing components. In this paper, we test the possibility of TR focusing on a defect within anisotropic, heterogeneous austenitic welds. A commercial simulation software is employed for TR focusing and imaging of a side-drilled hole. The performance of time reversed adaptive focal law is compared with those of calculated focal laws for both anisotropic and isotropic welds.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.27-30
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• 2004

본 논문에서는 사용자의 다양한 이질적인 사용 환경(단말기기, 네트웨크 품질 등)에 최적화된 멀티미디어 컨텐츠를 제공하는 시스템에 대해 제안한다. 제안된 시스템은 MPEG-21 멀티미디어 프레임워크를 기반으로 한다. 시스템은 클라이언트, 미디어 서버, 적응 변환 서버, 그리고 툴 서버로 구성된다. 또한 제안된 시스템은 사용자의 사용 환경 정보를 분석하고, 생성하는 사용 환경 정보에이전트 모듈과, 이를 받아 분석하는 정책 결정 엔진 모듈, 그리고 이를 제어하고 관리하는 제어모듈도 제공된다. 구성된 시스템에 대해 MPEG-2 교육 방송 컨텐츠에 대해 다양한 사용환경에 대해 적용하여 제안된 MPEGB-21 기반 서비스 시스템이 유효함을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.99-104
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• 1998

Application sharing is the ability to use existing applications, such as Excel or MS-Word, during a group session without modification. In this paper, we present the design and implementation of an application sharing system, called ShareIt, which enable users to share arbitrary MS-Windows applications under the Win 3.1/95/NT and X window system, and evaluation of the system performance. To share an application, the image of the application window is captured and transmitted to other sites. With the use of the window capturing method, ShareIt allows any MS-Windows application to be shared regardless of not only the window systems but also the version-up of window systems.

• Journal of Information Science Theory and Practice
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• v.1 no.1
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• pp.69-82
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• 2013

Although MAchine Readable Cataloging (MARC) and Functional Requirements for Bibliographic Records (FRBR) are currently the most broadly used bibliographic structures for generating bibliographic data in the library community, each has its own weaknesses in describing information resources in diverse media. If the MARC format could be implemented in a structure that reflects the multi-layered characteristics of FRBR, its use could address current problems and limitations in resource description. The purpose of this research is to propose an alternative approach that can integrate the heterogeneous bibliographic structures of MARC and FRBR through the applications of facet and facet analysis. The proposed faceted data model is expected to function as a conceptual structure that can mediate between MARC data elements and FRBR attributes in order to utilize these structures in a more reliable and comprehensive way.

• Electronics and Telecommunications Trends
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• v.22 no.6
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• pp.40-50
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• 2007

본 고에서는 이기종 네트워크 환경에서의 심리스 핸드오버 기술에 대한 기술 분석 및 관련 표준화 동향에 대하여 기술한다. 이기종 네트워크에서의 심리스 핸드오버 기술로 대표적인 IEEE 802.21 Working Group에서 표준화를 진행해온 Media Independent Handover 기술에 대한 참조 모델, 서비스, 프로토콜 및 이기종 네트워크간 핸드오버 절차를 중심으로 살펴본다. 최근 표준화 동향 파악을 위해서 2007년 10월 기준으로 IEEE 802.21 Working Group 및 IEEE 802.11u Task Group의 표준화 현황과 핵심 이슈를 정리하며, 그간 3GPP 표준과 연계한 MIH 기술 적용 현황 및 향후 추진시 고려할 사항에 대하여 기술한다. 또한, IEEE 802.21 Working Group 내 신규 그룹인 Multi-Radio Power Conservation Management Study Group과 Security Study Group의 진행상황에 대하여 살펴본다.

• Advances in environmental research
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• v.5 no.4
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• pp.263-282
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• 2016

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.11a
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• pp.128-133
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• 2007

Modern society changes so fast that it makes the borderlines obscure among all the elements in physical environments as well as culture and economy through rapid flows of Network or new media. Also these flows of changes appears and collides everywhere at the same time, which continuously generates heterogeneous environmental factors. For this reason, architecture is required to correspond with circumstances of the day, but it doesn't keep up with the speed of social changes actually because it features physically fixed construction. This research offers new direction and possibilities of architecture space elements using pluralistic and do-centering attributes of hypertext as a counterplan, and finds out how architecture space should correspond with the moving environment of modern society.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.5
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• pp.111-121
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• 1995

The initiation and propagation of detonation waves in the air/fuel spray mixture has been numerically analyzed. An improved pressure-based method has been applied to predict the transient heterogeneous reacting flows at all speeds. Numerical results indicate that variations in the temperature gradient, the droplet size, and the fuel vapor concentration have the significant effects on the development of detonation wave in the multi-phase reactive media. The interaction mechanism between the flame-generated pressure wave and the combustion wave is discussed in detail.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.06a
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• pp.192-193
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• 2019

최근 우리나라는 대형 산불 화재, 지진 및 복합 재난등 많은 위험에 노출이 되어 있는 상태이다. 대형 초고층 화재 및 산불 발생시 국민들에게 상황을 전달할 수 있는 시스템이 미비하여 신속하고 효과적으로 상황을 전파하고자, 현재 운영중에 있는 재난경보방송시스템과 화재플랫폼을 연계하여 상황을 신속하게 전파하고자 연구하였다. 본 논문에서는 초고층 빌딩화재와 재래시장화재 그리고 터널화재와 산불화재 가능성이 혼재되어 있는 테스트베드를 선정하여 화재 유형별로 전파되는 장소에 맞춰서 대비요령과 안내방송을 전파하는 것을 중점적으로 연구하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.2
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• pp.61-72
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• 2007

With the increasing growth of Internet and wireless IP networks, Multimedia systems need to be envisaged as information resources where users can access anywhere and anytime. However, efficient services in these multimedia systems are open and challenging research problem due to user mobility, limited resources in wireless devices and expensive radio bandwidth. To implement multimedia services over heterogeneous network, the IP header compression scheme can be used for saving bandwidth. In this paper, we present an efficient solution for header compression, which is modified form of ECRTP. It shows an architectural framework adopting modified ECRTP when IP tunneling network using GRE over IPSec is implemented. We have conducted simulations in order to analyze the effects of different header compression techniques while delivering real-time services to the wireless access network through secured IP Network. The impacts on performance have been investigated through a series of experiments.