• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.11 s.242
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• pp.1439-1444
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• 2005

A two-dimensional boundary element method was used for the scattering analysis of side-drilled hole(SDH). The far-field scattering amplitude was calculated for shear vertical(SV) wave, and their frequency and time-domain results were presented. The time-domain scattering amplitude showed the directly reflected wave from the SDH leading edge as well as the creeping wave. In an immersion, pulse-echo testing, two measurement models were introduced to predict the response from SDHs. The 2-D boundary element scattering amplitude was converted to the 3-D amplitude to be used in the measurement model. The receiver voltage was calculated fer SV wave incidence at 45$^{\circ}C$ on the 1 m diameter SDH, and the result was compared with experiment.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.67-69
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• 2000

분산 시스템은 원거리에 위치한 자원들을 하나의 시스템으로 통합하여 여러 가지 장점을 제공한다. 하지만 시스템의 규모가 커짐에 따라서 관리자 노드와 관리 대상 노드간의 빈번한 상호작용에 의해서 전체적인 시스템의 성능저하가 발생할 수 있다. 에이전트를 사용한 방법으로 중앙 집중형 관리 방법의 폴링(polling)에 따른 문제점을 해결하였으나 에이전트 사용에 있어서도 에이전트가 이동하는 파견방법에 따라서 성능의 차이가 발생할 수 있다. 즉, 에이전트를 파견하는 관리 대상 노드의 지역 계산 시간에 따라서 관리자 노드에서의 전체적인 응답시간과 네트워크의 부하가 달라질 수 있다. 따라서, 본 논문에서는 에이전트가 관리 대상 노드에서의 지역 계산 시간에 따라 현재 작업중인 노드의 다음 노드로 새로운 에이전트를 파견하여 관리자 노드에서의 응답시간과 네트워크 부하를 줄일 수 있는 방법을 제시하고 기존의 모델과의 평가를 응답시간과 네트워크 부하 측면에서 비교, 평가하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.644-650
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• 2001

A remotely located synchronization system which is locked to the remote master clock has been implemented by using GPS Common-View technique. The measurement results showed that the accuracy of the remote synchronization system could be kept within a few parts in $10^{-12}$ and MTIE(Maximum Time Interval Error) met the ITU-T Recommendation(G.811). A prototype system having fully automatic operational functions has been realized up to now and is expected to be used in the network synchronization in the near future.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.473-474
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• 2017

수도권 부하의 집중과 원거리 발전단지 위치는 우리나라 전력전송의 문제점이며, 전압형 HVDC 적용이 전력전송 문제의 대안이 되고 있다. 초기투자비가 높은 전압형 HVDC 사업의 경제적 타당성 확보의 방법은 기존 시장접근법의 부가가치 편익반영 외에 다른 각도의 다양한 편익산정법의 제안이 필요하다. 본 논문에서는 전압형 HVDC 사업 타당성 확보를 위한 피해비용저감방식의 다양한 편익을 도출하고 경제적 타당성을 제시하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.949-950
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• 2009

최근 들어 유전자원의 보존과 효율적인 관리에 대한 요구가 증가함에 따라 이러한 요구에 적합한 무선 인식기술로 RFID가 주목 받고 있다. 기존의 바코드 기술에 비해 RFID 시스템은 주파수를 이용하여 마이크로 칩이 내장된 태그의 정보를 비접촉식으로 원거리에서도 인식할 수 있으며 대량의 태그 인식 및 판독, 정보의 수정도 가능하여 이러한 장점으로 인해 여러 산업분야에서 사용되기 시작하였다. 이 논문은 축산, 유통 및 동물과 관련된 IT 산업에서 신속 정확한 정보 획득 및 정보보호의 방안으로 특정 그룹에 포함되는 객체들에 대한 접근이 가능한 태그의 구조를 제안하고 RFID 태그에 저장되어 있는 ID의 불법적인 유출을 방지하기 위한 프로토콜을 제안한다.

• Journal of the Korean Geographical Society
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• v.43 no.2
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• pp.202-219
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• 2008

As demand for high speed Internet service has explosively increased in the United States for the past decade, the construction or upgrades of telecommunication infrastructure has also been rapidly followed. Though currently many people in urbanized areas can be provided advanced broadband services, there are still challengeable areas to be served, such as remote or low populated areas because those areas are potentially non-profitable to commercial broadband service providers. This paper addresses the spatial disparity or in a broader term, the 'digital divide' of the broadband access by the county level in the United States. We propose the quantified measure of the county level broadband accessibility for identifying such digital divide. The developed measure is a hybrid form of the classical gravity based potential model and network topological accessibility, encouraged from the lack of prior efforts eying to explicitly incorporate the understanding of the whole process of the Internet access. The computational tasks are performed in a GIS platform, which includes several programmed functions.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.243-252
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• 2016

In this paper, the incoherent reverberation model based on coupled normal mode method is presented. In the range dependent environment, one way coupled normal mode method is used to calculate the pressure from a source to a scatterer patch and the pressure from a scatterer patch to a receiver. For the computational efficiency, the sound propagation from a source/receiver to the scatterer patch is assumed to occur only in the 2D plane where a source/receiver and scatterer patch are located. For the model verification, problems of the reverberation modeling workshop I and II sponsored by the US office of Naval Research are calculated and the results are compared with the incoherent reverberation model results based on the ray method.

• Journal of Elementary Mathematics Education in Korea
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• v.2 no.1
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• pp.61-80
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• 1998

Whereas research on telelearning in educational technology area is lively done, that in mathematics education area is not. Related to the open education, telelearning has 4 models: the distance classroom model, the front-end system design, the knowledge construction model, and the teaching model based on data. S/W, C/W, and H/W are the components of telelearning system. For an effective mathematics telelearning system, H/W and S/W which use multimedia with complex multimode information such as text, graphics, animation, video, and audio are necessary. Examples of telelearning systems on going are MIPOS, SDS telelearning system, telelearning system of the Naechon Elementary School, and Doorae Multimedia Application Development Platform.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.19-24
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• 2021

This paper presents a method to generate three-dimensional AR/VR models using the information in Isogen data files (IDFs). An IDF is an output file produced by ISOGEN that contains piping isometric drawings. A piping isometric drawing is used for pipeline installation in the shipyard; therefore, the drawing describes assembly information with symbolic features, not with detailed geometric features. An IDF specifies relationships between piping routes and components with three-dimensional points and tag information as well as the bill of the materials of a pipeline. The key idea of this paper is that AR/VR models can be generated with the piping route points data and piping components tag information in real time, without any conversion of standard data exchange file formats, such as STP, IGES, and SAT. This paper describes IDF data structure and suggests the geometry generation process with IDF data and parametric functions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.5
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• pp.473-479
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• 2004

In this paper, power density in near field is calculated about analytic object which has comparatively large volume in considering used wavelength such as cellular base station antenna. Panel sector antenna which is used widespreadly in domestic cellular wireless communication system is modeled and electromagnetic field distribution in reactive near field region is calculated by FDTD (Finite Difference Time Domain) method. After that, antenna gain in far field region is obtain by near to far transformation. Power spectral density in radiated near field is calculated in applying to gain-based model with antenna gain in far field. Finally, compliance distance is obtained in considering the result from radiated near field calculation and basic restrictions on occupational and general public exposure limits in ICNIRP guideline. In the center of main radiating position, the result from gain-based model is -14.55 ㏈m and the result from surface scanning method is -15.75 ㏈m. When the losses from cables and connectors used in measurement are considered, the results from gain-based model and surface scanning method are nearly coincident.