• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1407-1413
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• 1994

To obtain accurate target information in a radar system, clutter or interference signals must first be effectively removed for target detection. In this paper, the signal is projected onto a constrained orthogonal subspace, so that a minimum variance optimal detector is transformed into an unconstrained detector. The proposed algorithm is equivalent to the conventional optimal detector algorithm, and th algorithm structure shows that the Gram-Schmidt orthogonalization can be achieved to obtain the fast convergence. The performance of the proposed method was observed by simulation experiments.

• Journal of the Korean Geographical Society
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• v.38 no.5
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• pp.835-848
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• 2003

This study deals with the spatio-temporal change of land cover and vegetation distribution between 1988 and 2001 using remote sensing images and CIS techniques in west area of Pyeongbuk Province, northwest Korea. Landsat TM and ETM images are geometrically and radiometrically corrected for the analysis of land cover and NDVI. Forested areas are decreased during 13 year from 1988 to 2001 in study area including Sakju, Daegwan, Guseong and Euiju of Pyeongbuk Province, because wasteland are increased by human impact and denuded land by landslide and flooding. DEM analysis presents that settlement and cropland are developed toward higher and steeper mountain slope, together with decrease NDIV values. these changes have resulted from unplanned increase of cropland without consideration of geomorphic condition. Therefore, more researches and reasonable policies are required to protect forest and cropland and stable food supply against natural hazard like landslide.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.07a
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• pp.557-560
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• 2020

최근, 광소자에서 공간 변조되는 wavefront profile 특성을 광소자의 표면 단차 변화 없이 단일 두께 박막 상에서 자유로이 구현할 수 있는 기하위상 홀로그램 (geometric phase hologram) 기반의 optical component에 대한 관심이 증대되고 있다. 특히 이를 이용해 제작된 기하위상 렌즈 (geometric phase lens)는 dynamic phase의 공간적 차이에 의해 구현되던 기존 bulk optics 기반의 lens 대비 초박형으로 제작이 가능한 파장 선택적 flat optics 기술로써, 다초점 및 경량화를 요구하는 차세대 디스플레이 기술 (augmented reality 또는 AR, mixed reality 또는 MR) 및 광파변조 및 제어를 요구하는 홀로그래픽 카메라 분야에 대한 응용처로 많은 주목을 받고 있다. 이에 본 논문에서는 해당 기하 위상렌즈에 대한 원리 및 이에 따른 개발이슈 및 해결법에 대해 연구 하였으며, 이에 대한 응용처로 기하위상 렌즈의 편광에 따른 이중초점특성을 이용해, 기존 단일 초점 형성이 가능한 AR기기 대비, 다초점 형성이 가능한 switchable dual-depth 3D AR device를 compact한 모듈과 함께 구현하였다. 또한, 기하위상렌즈의 광파 변조 및 분리특성을 이용한 기하위상 렌즈기반의 자가간섭 홀로그래픽 시스템(GP-self-interference incoherent digital holographic, GP-SIDH)에 편광 이미지센서 적용과 함께 맞춤형 설계/제작된 기하 위상렌즈를 적용함으로써, 기존 GP-SIDH 시스템대비 안정적으로 실시간 복소 홀로그램 획득이 가능한 실시간 공간영상정보 획득용 GP-SIDH을 동영상 프레임으로 구현하였다.

• Journal of the Korean association of regional geographers
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• v.17 no.1
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• pp.1-16
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• 2011

Today, the name of Changjiang (Yangtze) Delta Region is used to designate an economic region which consists of sixteen cities including Shanghai City. The region has achieved the highest rate of economic growth in the world as well as in China since China its opened its toward the world market. The aim of this study is to examine the modern transition of spatial structure in the region after the opening (1978) and the membership of WTO (2000). In the examination, the study divides the spatial structure into three aspects: industrialization, urbanization and economic integration. The outcome of examination suggests that spatial division of industry, horizontally and vertically, has not reached a satisfactory level even if it is still in progress. The study proposes that the intervention of government in the market and company activity has hindered the spatial division of industry including service sector between the cities, and thus the economic integration. It further suggests that the specialization of urban function has not entered into the maturing stage, with the shortage of mid-size cities that would mediate spatial-economically between the large-size cities and the small-size cities in the urban hierarchy.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.2
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• pp.93-102
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• 1995

A series of test was performed by measuring the failure strength and the failure mode of fiber reinforced composite laminates joint containing two holes in Series or Parallel. $[0^{\circ}/45^{\circ}/90^{\circ}/-45^{\circ}]_s$ laminate with W/d(Side distance ratio) 4.0 and E/d(Edge distance ratio) 3.0 has the full bearing strength and are preferable in case of the good efficiency in two series hole. Comparisons were made between testing results and predicting values of the FEM model. Good agreements were fecund between them except the case of $E/d=2{\sim}3$. In the case of $G_h{\geq}3.0d$ and $G_v{\geq}3.0d$ since the interaction coefficients between two parallel holes and between two series holes were small, holes can be treated as independent. The Acoustic Emission(AE) and SEM method were utilized to find out the initial defects, damage and the fracture mechanism.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.4
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• pp.387-401
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• 2007

Recently, because of the restriction of land for construction and interference of adjacent structure, parallel tunnels with small clearance have been planned and constructed in many sites. In this case, the stability of pillar at center part is very important factor to satisfy the stability of tunnel structure under the construction. In this paper, numerical analyses for the asymmetry parallel tunnels with a narrow width of pillar have been carried out to search for the optimum reinforcement measure for rock pillar and verify the stability of tunnel. Rock pillar between each single tunnel is supposed to be under heavy load by rock mass. The analysis of stress state at rock pillar at various cases for construction conditions is required to investigate the structural behaviour of tunnels and stability of the pillar. Strength-stress ratio is calculated based on the failure theory of rock and the safety factor of tunnel is computed with strength reduction technique. Through these numerical results, reasonable reinforcement measures for rock pillar at parallel tunnel were established and recommended.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.199-201
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• 2002

데이터베이스시스템에서 트랜젝션의 동시성제어에 관련된 문제를 해결하고 성능을 향상시키기 위해서 않은 기법들이 소개되어졌다. 그 중에서 멀티버전(Multi-Version) 알고리즘은 각 트랜잭션간의 상호간섭을 최소화시키면서 동시성을 향상시키기 위한 알고리즘 중 하나이다 하지만 멀티버전 알고리즘은 데이터베이스이 레코드에 대한 버전을 저장하기 위한 저장공간의 낭비와 버전에 대만 최신의 정보론 유지하기 위한 Garbage Collection 연산의 부하가 따른다. 본 논문에서는 트랜잭션간의 동시성을 망상시키기 위한 방법으로 시스템의 메모리 광간에 일시적인 레코드의 버전을 생성하여 버전 풀(Version Pool)을 관리하여 레코드의 안정된 버전(Stable version)을 관리할 수 있는 기법을 제안한다. 판독트랜잭션은 안정된 버전을 찾기 위해 별도의 연산에 대한 부하없이 버전 플에서 가장 먼저 생성된 버전을 읽어오기만 하면 된다. 또한 갱신 트랜잭션은 로크(Lock)을 사용하지 않고 레코드의 갱신을 데이터베이스에 곧바로 반영하며, 판독 트랜잭션도 판독연산에 로크를 사용하지 않고 버전 풀에서 관리하는 레코드의 안정된 버전을 선택하여 읽어 가는 기법을 제안한다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.16-17
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• 2000

무선광통신기술은 케이블의 신설 또는 재 설치가 어려운 구간이나 보안성이 요구되는 무선전송 구간에 많이 사용된다. 또한 기존의 무선주파수와 상호간섭이 적으며, 구현이 간편하여 실내의 짧은 광 전송구간과 빌딩간의 고속광전송에 그 이용이 점점 증가하고 있다$^{(1-5)}$ . LOS(Line of sight)방식의 광연결에서는 광원으로부터의 출력빔의 방향과 광검출기의 위치가 잘 정렬되어야 한다. 광원으로부터 광검출기 사이의 신호전송매체가 자유공간이므로 외부의 기계적 진동에 의하여 광원의 위치가 미소하게 변경되는 경우, 출력광의 진행방향이 광검출기의 위치에 일치하지 않아 수신부에서 검출되는 신호는 매우 약해질 수 있다. 본 논문에서는 이러한 경우에 효과적으로 사용할 수 있는 자동정렬형 광검출구조를 개발하였다. 자동정렬형 광검출기의 구조도는 그림[1]과 같다. (중략)

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2002.11a
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• pp.487-489
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• 2002

Recently, mobility and accessibility occurs for the elder and the handicapped in the aging problem. In this paper, we analyze the dynamics of slide-up seat, which helps to care the handicapped passenger in and out the automobile when we enjoy trip with the families including the elder and handicapped. We check the trajectories of slide-up seat inside and outside car to protect its corrosion and the stress at the joints of mechanical structure. Those can be helped to keep the safety and accuracy of the multiple dynamic systems for precision quality assurance in mass production.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2002.11a
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• pp.487-489
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• 2002

Recently, mobility and accessibility occurs for the elder and the handicapped in the aging problem. In this paper, we analyze the dynamics of slide-up seat, which helps to care the handicapped passenger in and out the automobile when we enjoy trip with the families including the elder and handicapped. We check the trajectories of slide-up seat inside and outside car to protect its corrosion and the stress at the joints of mechanical structure. Those can be helped to keep the safety and accuracy of the multiple dynamic systems for precision quality assurance in mass production.