• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.5
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• pp.369-377
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• 1999

Recently, it is gradually raised necessity that thickness of thin film is measured accuracy and managed in industrial circles and medical world. Ultrasonic signal processing method is likely to become a very powerful method for NDE method of detection of microdefects and thickness measurement of thin film below the limit of ultrasonic distance resolution in the opaque materials, provides useful information that cannot be obtained by a conventional measuring system. In the present research. considering a thin film below the limit of ultrasonic distance resolution sandwiched between three substances as acoustical analysis model, demonstrated the usefulness of ultrasonic signal processing technique using information of ultrasonic frequency for NDE of measurements of thin film thickness. Accordingly, for the detection of delamination between the junction condition of boundary microdefect of thin film sandwiched between three substances the results from digital image processing.

• 한국지형공간정보학회:학술대회논문집
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• 1995.10a
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• pp.99-119
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• 1995

Most studies using satellite images have been performed to determine three dimensional positioning by stereoscopic analysis for stereo-pair or to extract digital elevation model by stereo matching using image correlation techniques. Because the small errors on the ground control points have a great impact on the results, honorer, it is hard to get reliable products when we analyze satellite orbital parameters or acquire digital elevation model by using only stereo-pair. Also, if there are noises, shadows, or clouds on the one of stereo pair, it is difficult to produce DEM(digital elevation model) on the area under analysis or to have good accuracy. In these case, it can be solved by systematic analysis of the multiple stereo images. This paper suggests the improvements on the accuracy of the digital elevation model by the developments of stereoscopic analysis techniques for the triplet of SPOT satellite images on the same area.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.68-76
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• 2006

We propose a low noise broadband light source (BLS) and investigate a cost-effective wavelength division multiplexing-passive optical network (WDM-PON) for the convergence of broadcasting and data service. The proposed BLS is used for an injection light of wavelength-locked Fabry-Perot laser diodes (F-P LD) and helps the color-free operation of dense WDM-PON (DWDM-PON). In addition, we apply this BLS to a optical source for overlay of digital broadcasting channel on the WDM-PON.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.3
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• pp.217-227
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• 1989

A process control graphic system is proposed as an efficient tool for monitoring the operation of power plant. It uses the multi-processor structure with 60 Kbyte shared memory as an implemental type of the distributed computer system, so that it is flexible, functionally extensible, and applicable to real-time process. The shared memory is used as a real-time database handling the process values and operator's commands. The database files, generated by the user-interactive graphic editor developed for the system or text editor, have the characteristics of simplicity and user-friendliness. The process control graphic system, that can monitor the operation of boiler and function as a backup controller in case of failure in boiler controller, is applied to Ulsan power plant. As a result, it displays the operating data of the boiler process without error by 14 pages of color graphic image according to the operation menu, and additionally functions well as a fault-tolerant control system.

• Journal of Fashion Business
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• v.7 no.5
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• pp.108-118
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• 2003

Surface properties, including the texture and the luster, of cotton fibers and yarns thereof play an important role in textile technology. The convolutions and the cross-sectional shape of the cotton fiber affect the fabric texture and the luster accordingly. Mercerization of the cotton fabric affects the luster, strength, and other properties of the fabric. In this study, the effect of mercerization was examined on the luster of the cotton fabric, together with the effect of polishing treatment. One of the traditional methods determining the fabric luster is the use of glossmeter or goniometric glossmeter. The use of glossmeter gives successful results in determining the gloss of rather flat and continuous surface such as plastic sheet, painted surface, or paper products. Since the textile fabrics have diverse surface structures and textures, these could be regarded as having three-dimensional surface. Such complexity imposes some difficulties for differentiating subtle surface luster properties of diverse textile fabrics. The advancement in the area of imaging technologies has enabled the micro-scale analysis of the surface textures and the fabric luster recently. Using a CCD camera, the surface luster images were taken at various incident illumination conditions. Microscale analysis, including the blob analysis, of the images could differentiate the subtle luster properties present in a group of cotton fabric samples comprising mercerized cotton fabric, non-mercerized cotton fabric, polished cotton fabric, and a 'standard' cotton fabric. The glossmeter measurement gave satisfactory but limited differentiation among the samples, whose luster differences are easily recognizable with visual observation, except for the mercerized cotton fabric sample and the non-mercerized cotton fabric. The microscale analysis of the fabric luster could, therefore, help understand the nature of diverse textile fabric luster.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.532-534
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• 2005

최근 컴퓨팅 환경의 변화와 함께, 무선 환경에서 발생할 수 있는 다양한 제약사항들을 극복할 수 있는 적응형 시스템에 대한 연구 필요성이 갈수록 높아지고 있다. 본 논문에서는 기존에 다양한 방법으로 연구되고 있는 적응형 시스템들의 단점을 보완하고, 장점을 취합하여, 클라이언트와 프록시 서버에 작업 모듈을 적절히 분산시킨 Hybrid형 시스템을 제안한다. 제안시스템은 주변상황을 인식하고, 이에 대한 대응방안을 결정하는 작업은 클라이언트에서 수행하며, 미디어 콘텐츠를 직접 변경하는 적응 작업은 상대적으로 리소스가 풍부한 프록시 서버에서 수행한다. 이를 통해, 클라이언트와 프록시 서버는 적응에 대한 계산 부하를 적절히 나누어 갖게 되며, 미디어 콘텐츠의 조절뿐만 아니라 실행되고 있는 애플리케이션의 파라매터도 조절이 가능해진다. 또한 클라이언트는 단지 결정에 대한 지시만을 서버로 전송함으로써, 전송되는 메시지의 양을 줄일 수 있고 작업내역과 같은 개인정보 유출을 방지할 수 있다. 본 논문에서는 제안 시스템을 멀티미디어 통신인 '화상회의시스템'에 적용하여 기능을 실험하였으며, 기존의 적응형 시스템들과 기능적 비교를 통해 본 시스템의 유효성을 평가하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.9
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• pp.1824-1837
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• 1994

Broadband ISDN will support advanced communication services such as multimedia conference, VOD and electronic news service. Because many of these advanced services require multimedia data delivery, future communication networks must have flexible and efficient multiparty communications capabilities. In this paper we propose a new multicasting method which uses packer filtering capabilities both in a physical network and in a logical network layers. This new scheme has potential to reduce the transmission and packet processing overheads of multicast communications. For the new multicasting method, we develop a group matching algorithm which finds a suitable set of groups that covers multiple target hosts. We show the application of the multicasting method and the group matching algorithm with two simple examoles.

• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.651-658
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• 2005

Mobile communication has become more pervasive and it is considered as one of main concerns oi conferencing, multi-user games and etc. in mobile environment. These applications need to secure communication in group. Most of the published protocols are based on model which consists of a stationary base station and a cluster of mobile devices. In this paper, we have focused on the extended model of which participants are several base stations and mobile devices in different cells. We present a new group key protocol among mobile devices in different cells and analyze its security And we also look at how password authentication can be used to our group key agreement protocol. The mobile device's computing load may be reduced by using password authentication.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2205-2208
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• 2003

대부분의 인터넷 서비스는 일대일 전송방식의 best-effort를 지향하는 유니캐스트(Unicast)가 보편화 되어있다. 하지만, 다자간 통신 서비스는 고려하지 않아 망 자원 이용측면에서 매우 비효율적이다. 최근, 인터넷방송이나 소프트웨어 분배, 원격 화상회의, 다중사용자 게임, 증권시세 정보서비스 등 다자간 멀티미디어 서비스가 주요 인터넷 사업으로 각광을 밭으면서, 멀티캐스트(Multicast) 전송기술의 사용범위가 점차 증가되고 있다. 멀티캐스트는 그룹참가자의 가입과 탈퇴가 빈번한 특징이 있어 키 전달 과정에서 네트워크의 과부하를 초래한다. 본 논문에서는 빈번하게 생성되는 그룹 키의 길이를 축소시켜 메시지의 생성과정을 단축하고, 독립된 그룹간 통신에 사용되는 유니캐스트에 IPSec(Internet Protocol Security Protocol)을 적용시켜 보다 안전하게 구간의 접근제어와 무결성 및 기밀성을 보장하는 SDKD(Secure Dynamic Key Distribution)를 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.4
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• pp.77-89
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• 2001

Recently, with the explosive growth of communication technologies, group oriented services such as teleconference and multi-player game are increasing. Access control to information is handled by secret communications with group keys shared among members, and efficient updating of group keys is vital to such secret communications of large and dynamic groups. In this paper, we employ (2,4)-tree as a key tree, which is one of height balanced trees, to reduce the number of key updates caused by join or leave of members. Especially, we use CBT(Core Based Tree) to gather network configurations of group members and reflect this information to key tree structure to update group keys efficiently when splitting or merging of subgroups occurs by network failure or recovery.