D.C magnetron sputter법으로 증착된 TiAlN의 중간층에 따른 특성연구

김명호,이도재,이광민,김운섭,김민기,박범수,양국현,Kim, Myoung-Ho,Lee, Doh-Jae,Lee, Kwang-Min,Kim, Woon-Sub,Kim, Min-Ki,Park, Burm-Su,Yang, Kook-Hyun 한국재료학회 2008 한국재료학회지 Vol.18 No.10

TiAlN films were deposited on WC-5Co substrates with different buffer layers by D.C. magnetron sputtering. The films were evaluated by microstructural observations and measuring of preferred orientation, hardness value, and adhesion force. As a process variable, various buffer layers were used such as TiAlN single layer, TiAlN/TiAl, TiAlN/TiN and TiAlN/CrN. TiAlN coating layer showed columnar structures which grew up at a right angle to the substrates. The thickness of the TiAlN coating layer was about $1.8{\mu}m$, which was formed for 200 minutes at $300^{\circ}$. XRD analysis showed that the preferred orientation of TiAlN layer with TiN buffer layer was (111) and (200), and the specimens of TiAlN/TiAl, TiAlN/CrN, TiAlN single layer have preferred orientation of (111), respectively. TiAlN single layer and TiAlN/TiAl showed good adhesion properties, showing an over 80N adhesion force, while TiAlN/TiN film showed approximately 13N and the TiAlN/CrN was the worst case, in which the layer was destroyed because of high internal residual stress. The value of micro vickers hardness of the TiAlN single layer, TiAlN/TiAl and TiAlN/TiN layers were 2711, 2548 and 2461 Hv, respectively.

자가 슬건과 동종 전경골건을 이용한 전방십자인대 재건술 후 시행한 이차 관절경의 결과 비교

김명호 ( Myung Ho Kim ),유문집 ( Moon Jib Yoo ),박희곤 ( Hee Gon Park ),유현열 ( Hyun Yul Yoo ),이대희 ( Dae Hee Lee ) 대한슬관절학회 2010 대한슬관절학회지 Vol.22 No.1

Purpose: We wanted to evaluate the status and changes of the reconstructed anterior cruciate ligament (ACL) graft by performing second-look arthroscopy after arthroscopic reconstruction of the ACL with a hamstring autograft or a tibialis allograft. Materials and Methods: From June 2003 to February 2007, second look arthroscopy was performed on 58 cases and a hamstring autograft was used in 36 cases and a tibialis allograft was used in 22 cases. Second-look arthroscopy was conducted at an average of 19.1 (12~42) months after reconstruction. We measured the graft tension using displacement by probing and the synovial coverage by visual analysis at the time of second-look arthroscopy. The Lysholm score, the Lachman test and a KT-2000 arthrometer were used to evaluate the status of the reconstructed ACL. Results: The hamstring tendon autograft group showed normal tension in 25 cases, lax tension in 7 cases and partial tear in 4 cases. The tibialis anterior allograft group showed normal tension in 12 cases, lax tension in 5 cases and partial tear in 5 cases. In the hamstring tendon autograft group, the synovial coverage was good in 23 cases, there was half coverage in 8 cases and it was pale in 5 cases. In the tibialis anterior allograft group, the synovial coverage was good in 10 cases, there was half in 7 cases and it was pale in 5 cases. There were no significant differences between the two groups on the clinical examination, but on second look arthroscopy, the synovial coverage was better in the hamstring tendon autograft group than that for the tibialis anterior allograft group. Conclusion: The hamstring autograft group had superior synovial coverage compared to that of the other group on second look arthroscopy. But there were no significant difference of the clinical outcomes between the groups.

PC / PMMA 블렌드의 상거동과 기체투과 특성

김명호(Myung Ho Kim),김창근(Chang Keun Kim),강용수(Yong Soo Kang),박현채(Hyun Chae Park),원종옥(Jong Ok Won) 한국고분자학회 1997 폴리머 Vol.21 No.6

시공간 데이타베이스의 엔트로피 기반 동적 히스토그램

박현규(Hyun Kyoo Park),손진현(Jin Hyun Son),김명호(Myoung Ho Kim) 한국정보과학회 2003 정보과학회논문지 : 데이타베이스 Vol.30 No.2

Various techniques including histograms, sampling and parametric techniques have been proposed to estimate query result sizes for the query optimization. Histogram-based techniques are the most widely used form for the selectivity estimation in relational database systems. However, in the spatio-temporal databases for the moving objects, the continual changes of the data distribution suffer the direct utilization of the state of the art histogram techniques. Specifically for the future queries, we need another methodology that considers the updated information and keeps the accuracy of the result. In this paper we propose a novel approach based upon the duality and the marginal distribution to construct a histogram with very little time since the spatio-temporal histogram requires the data distribution defined by query predicates. We use data synopsis method in the dual space to construct spatio-temporal histograms. Our method is robust to changing data distributions during a certain period of time while the objects keep the linear movements. An additional feature of our approach supports the dynamic update incrementally and maintains the accuracy of the estimated result. 질의 최적화에 사용하기 위한 선택도 추정 방법은 히스토그램, 샘플링 그리고 패러미터에 의한 요약 방법 등이 제시되고 있다. 히스토그램을 이용한 선택도 추정은 상용 데이타베이스 시스템에서 가장 보편적으로 사용되는 방법이지만, 이동 객체를 위한 시공간 데이타베이스에서는 데이타 분포가 지속적으로 변화함으로써 기존의 히스토그램 방법을 이용하는 것은 제한이 많게 된다. 특히 미래 질의를 위해서는 데이타 갱신을 반영하는 동적 관리가 가능하며, 정확도를 유지할 수 있는 다른 접근 방법이 필요하다. 따라서 시공간 객체를 위한 선택도 추정 방법은 질의 술어가 요구하는 데이타 분포에 대한 히스토그램이 필요하며, 본 논문에서는 미래의 시공간 영역 질의 술어에 대하여 신속히 히스토그램을 생성할 수 있도록 쌍대성과 한계 분포 방법을 이용한 히스토그램을 제안한다. 쌍대 공간에서 이동 객체에 대한 데이타 시놉시스를 이용하여 구성된 시공간 히스토그램은 이동 궤적의 선형성이 유지하는 시간 동안 정확성을 보장하면서 빠른 시간에 생성이 가능하다. 또한 동적 갱신을 점증적으로 지원함으로써 효율적으로 갱신된 정보를 반영할 수 있고 추정 결과의 정확성을 향상시킬 수 있다.

위치 기반 서비스에서 연속 근사 질의 처리

박현규(Park Hyun Kyoo),김명호(Kim Myoung Ho) 한국정보과학회 데이터베이스 소사이어티 2002 데이타베이스 연구 Vol.18 No.4

효율적인 위치 기반 서비스를 위한 다중 버전 기반의 시공간 색인 기법

박현규(Hyun Kyoo Park),손진현(Jin Hyun Son),김명호(Myoung Ho Kim) 한국정보과학회 2003 정보과학회논문지 : 데이타베이스 Vol.30 No.1

시간에 따라 변화하는 공간 속성을 다루는 시공간 데이터베이스는 이동 통신 환경에서 위치 기반 서비스를 제공하기 위한 중요한 연구 분야이다. 이동 통신, 교통 관리 그리고 군사 목적의 지휘 통제 시스템 등의 다양한 영역에서 시공간 데이터의 효율적인 관리가 요구되고 있지만, 지속적인 위치 변화로 인한 객체들의 정확한 위치 정보를 데이터베이스에 유지하는 것은 어렵다. <br/> 본 논문에서는 다중 버전 B-트리 기반의 Bst-트리 색인 구조를 제안 한다. Bst-트리는 이동 객체들의 궤적에 대한 효율적인 이력 및 미래 영역 질의를 지원할 수 있다. 또한 동적 버전 관리 알고리즘을 통하여 항상 일정한 질의 처리 성능이 유지될 수 있도록 객체들의 이동 형태에 따라 버전을 유지한다. 그리고 다양한 실험을 통하여 본 논문에서 제안된 색인 방법의 유용성을 보인다. The spatiotemporal database concerns about the time-varying spatial attributes. One of the important research areas is related to the support of various location-based services in mobile communication environments. It is known that database systems may be difficult to manage the accurate geometric locations of moving objects due to their continual changes of locations. However, this requirement is necessary in various spatiotemporal applications including mobile communications, traffic control and military command and control (C2) systems. <br/> In this paper we propose the Bst-tree that utilizes the concept of multi-version B-trees. It provides an indexing method for the historical and future range query processing on moving object´s trajectories. Also we present a dynamic version management algorithm that determines the appropriate version evolution induced by the mobility patterns to keep the query performance. With experiments we show that our indexing approach is a viable alternative in this area.

급속응고한 Al-Mg-Be 합금의 미세조직 및 인장특성

이인우,박현호,김명호 ( In Woo Lee,Hyun Ho Park,Myung Ho Kim ) 한국주조공학회 1996 한국주조공학회지 Vol.16 No.4

N/A Twin roll quenched Al-Be ribbons were vacuum hot-pressed at 450℃ under 100㎫ and hot-extruded with reduction in area of 25:1 at 450℃. The extruded Al-Be ribbons consisted of refined Al grains and homogeneously dispersed fine Be particles, and exhibited improved tensile properties with increasing of solidification rate and Be contents. Also in order to develop a light weight-high strength Al alloy, rapidly solidified Al-Mg-Be alloy system was studied. Rapidly solidified Al-Mg-Be alloy by twin roll quenching process was vacuum hot -pressed and subsequently hot-extruded. Compared with extruded Al-Mg ribbons, extruded Al-Mg-Be ribbons exhibited finer recrystallized grains and improved tensile properties, as subgrain boundaries of extruded Al-Mg-Be ribbons were pinned by fine Be particles. With increasing of solidification rate and Mg contents, extruded Al-Mg-Be ribbons exhibited very fine recrystallized grains and improved tensile properties. These tendencies could be due to promoted recrystallization by refined Be particles. T4 treatment for the extruded Al-13Mg-1Be ribbons was found to improve the elongation, possibly by the resolution of Al₃Mg₂at grain boundaries.

급속응고한 Al-Mg 합금의 미세조직 및 인장특성에 미치는 첨가원소의 영향

박현호,박종성,김명호 ( Hyun Ho Park,Chong Sung Park,Myung Ho Kim ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.4

N/A In order to study effects of Cu and lie on the microstructure and tensile properties of rapidly solidified Al-Mg alloys, Al-Mg-Cu-Be alloys have been rapidly solidified by inert gas atomization process. Microstructure of rapidly solidified Al-Mg-Cu-Be powders exhibited refinement and good dispersion of Be particles as increasing of solidification rate. Solidification rate of atomized powders was estimated to be about 5 × 10^(3n)C/s. Inert gas atomized Al-Mg-Cu-Be powders were hot-processed by vacuum hot pressing at 450℃ under 100 MPa and hot extruded with reduction ratio in area of 251 at 450℃. The extruded Al-Mg-Cu-Be. powders consisted of recrystallized fine A1 grains and homogeneously dispersed fine Be particles, and exhibited improved tensile properties with increase in Cu content. Al₂CuMg compounds precipitated in grain and grain boundaries of Al-Mg-Cu-Be alloys with aging heat treatment after solution treatment. Hardness and tensile properties were improved by increasing Cu content and Be addition. Compared with extruded Al-Mg-Cu powders, the extruded Al-Mg-Cu-Be powders exhibited finer recrystallized grains and improved tensile properties by dispersion hardening of Be and subgrain boundaries pinned by fine Be particles. After aging treatment, hardness and tensile properties were improved due to restricted precipitation by increasing of dislocation density around Be particles in matrix.

이동 객체의 현재 위치 색인 기법

박현규,강성탁,김명호,민경욱,Park, Hyun-Kyoo,Kang, Sung-Tak,Kim, Myoung-Ho,Min, Kyoung-Wook 한국공간정보학회 2003 개방형지리정보시스템학회 논문지 = Journal of the Korea Open Geogr Vol.5 No.1

Location-based service is an important spatiotemporal database application area that provides the location-aware information of wireless terminals via positioning devices such as GPS. With the rapid advances of wireless communication systems, the requirement of mobile application areas including traffic, mobile commerce and supply chaining management became the center of attention for various research issues in spatiotemporal databases. In this paper we present the A-Quadtree, an efficient indexing method for answering location-based queries where the movement vector information (e.g., speed and velocity) is not presented. We implement the A-Quadtree with an index structure for object identifiers as a.Net component to apply the component to multiplatforms. We present our approach and describe the performance evaluation through various experiments. In our experiments, we compare the performance with previous approaches and show the enhanced efficiency of our method. 위치 기반 서비스는 이동 통신 단말기의 위치를 GPS 등을 이용하여 실시간 위치 정보와 관련된 정보를 제공하는 응용 서비스로서 이동 통신망의 고도화에 따라 교통, 물류, 전자 상거래 등의 분야에서 시공간 데이터베이스의 주요한 응용 영역으로 부각되고 있다. 속도와 이동 방향과 같은 궤적 정보가 제공되지 않는 이동 통신 환경에서 지속적으로 변화하는 이동 객체의 위치를 효율적으로 색인하는 방법으로 본 논문에서는 A-Quadtree를 제시한다. A-Quadtree는 2차원 위치 정보를 실시간 갱신을 지원하는 구조로서 객체 식별자에 대한 색인과 통합하여.Net 콤포넌트로서 구현함으로써 다양한 플랫폼에 적용이 가능하도록 하였다. 또한 실험을 통하여 A-Quadtree는 기존의 다차원 색인 구조보다 갱신과 검색 성능이 효율적임을 보인다.

Peripheral Neuroepithelioma of Ulnar Nerve

Seung Rim Park(박승림),Myung Ho Kim(김명호),Hyoung Soo Kim(김형수),Kyoung Ho Moon(문경호),E Hwan Kim(김이환),Kwang Hyun Lee(이광현) 대한정형외과학회 1993 대한정형외과학회지 Vol.28 No.4