토목섬유튜브를 이용한 준설토 투기장 호안 설계사례

이충호,Lee, Chung-Ho (사)한국토질및기초기술사회 2009 지반과 기술 Vol.6 No.3

확장 가능한 고가용 데이터베이스 클러스터에서 B⁺ 트리 색인의 온-라인 재조직 기법

이충호,배해영,Lee, Chung-Ho,Bae, Hea-Young 한국정보처리학회 2002 정보처리학회논문지D Vol.9 No.5

온-라인 재조직 기법은 인터넷 환경과 같은 동적 환경에서 높은 가용성과 고성능을 제공하기 위한 비공유 데이터베이스 클러스터의 필수적인 기능이다. 기존의 온-라인 재조직 기법은 클러스터 안의 프로세싱 노드에 과부하가 생긴 경우, 과부하 노드의 데이터를 인접 노드로 빠르게 이동시킴으로써 부하 분배를 수행한다. 그러나 동시에 두개 이상의 다중 노드에 과부하가 발생된 경우, 부하 분배를 위해 인접 노드로 여러 번의 반복된 데이터 이동이 발생되고, 재조직 수행동안 시스템의 응답 속도가 늦어지는 문제점이 있다. 본 논문에서는 다중 노드에 발생한 과부하 문제를 빠르고 효율적으로 해결하는 향상된 $B^{+}$트리 색인의 온-라인 재조직 기법을 제안한다. 제안된 기법은 확장 가능한 데이터베이스 클러스터 환경 하에 온-라인 확장을 통해 새롭게 추가된 노드들에 데이터를 이동시킴으로써 데이터 이동의 회수를 줄이면서 빠른 시간 안에 온-라인 재조직을 수행하도록 한다. 또한 제안된 기법에서는 $B^{+}$-트리 색인 대신 캐시를 고려한 CS$B^{+}$-트리 색인을 이용하여 검색과 갱신 연산을 보다 빠르게 처리하도록 한다. 제안된 온-라인 재조직 기법은 확장 가능한 고가용 데이터베이스 클러스터 시스템으로 개발된 최대 결함허용 보장 데이터베이스 클러스터(Ultra Fault-Tolerant Database Cluster) 환경에서 성능 평가를 통해 기존 기법에 비해 빠르고 효율적임을 보인다. On-line reorganization in a shared nothing database cluster is crucial to the performance of the database system in a dynamic environment like WWW where the number of users grows rapidly and changing access patterns may exhibit high skew. In the existing method of on-line reorganization have a drawback that needs excessive data migrations in case more than two nodes within a cluster have overload at the same time. In this paper, we propose an advanced B$^{+}$ tree based on-line reorganization method that solves data skew on multi-nodes. Our method facilitates fast and efficient data migration by including spare nodes that are added to cluster through on-line scaling. Also we apply CSB$^{+}$ tree (Cache Sensitive B$^{+}$ tree) to our method instead of B$^{+}$ tree for fast select and update queries. We conducted performance study and implemented the method on Ultra Fault-Tolerant Database Cluster developed for high scalability and availability. Empirical results demonstrate that our proposed method is indeed effective and fast than the existing method. method.

스톤컬럼[Stone Column]공법의 최신 설계법과 적용

이충호,김종수,강현준,Lee, Chung-Ho,Kim, Jong-Su,Gang, Hyeon-Jun 한국지반공학회 2005 지반 : 한국지반공학회지 Vol.21 No.2

박판금속성형의 초기 블랭크 최적설계를 위한 삼차원 다단계 역해석

이충호,허훈,Lee, Choong-Ho,Huh, Hoon 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.12

Values of process parameters in sheet metal forming can be estimated by various one-step inverse methods. One-step inverse methods based on deformation theory, however, cause some amount of error. The amount of error is generally increased as the deformation path becomes more complex. As a remedy, a new three dimensional multi-step inverse method is introduced for optimum design of blank shapes and strain distributions from desired final shapes. The approach extends a one-step inverse method to a multi-step inverse method in order to reduce the amount of error. The algorithm developed is applied to square cup drawing to confirm its validity by demonstrating reasonably accurate numerical results. Rapid calculation with this algorithm enables easy determination of an initial blank of sheet metal forming.

박판금속 성형공정에서의 블랭크 설계및 변형률 예측

이충호,허훈,Lee, Choong-Ho,Huh, Hoon 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.6

A new finite elemetn approach is introduced for direct prediction of bland shapes and strain distributions from desired final shapes in sheet metal forming. The approach deals with the geometric compatibility of finite elements, plastic deformation theory, minimization of plastic work with constraints, and a proper initial guess. The algorithm developed is applied to cylindrical cup drawing, square cup drawing, and fron fender forming to confirm its validity by demonstratin reasonable accurate numerical results of each problems. Rapid calculation with this algorithm enables easy determination of various process variables for design of sheet metal forming process.

확산 신경 회로망을 이용한 광대역 공간 주파수 성분의 윤곽선 검출

이충호,권율,김재창,남기곤,윤태훈,Lee, Choong-Ho,Kwon, Yool,Kim, Jae-Chang,Nam, Ki-Gon,Yoon, Tae-Hoon 대한전자공학회 1995 전자공학회논문지-B Vol.b32 No.1

The diffusion neural network forms a Gaussian distribution by transferring an excitation to the surround. A DOG(difference of two Gaussians) is obtained by the diffusion neural network. This type of the DOG, which can detect the intensity changes of an image, has the same shape as a LOG(Laplacian of a Gaussian:${\Delta}^2$G) and narrow band pass characteristics. In this paper we show that another type of the DOG which has a very narrow Gaussian for the excitatory and a very wide Gaussian for the inhibitory, can be formed by the diffusion process of this network, This type of the DOG has a wide band width in spatial frequency domain and can be used efficiently in detecting special type of edges.

치아절제술이 시행된 증례의 임상적 평가 : 2년 이상 경과한 증례의 평가

이충호,박진우,서조영,이재목,Lee, Chung-Ho,Park, Jin-Woo,Seo, Jo-Yeong,Lee, Jae-Mok 대한치주과학회 2006 Journal of Periodontal & Implant Science Vol.36 No.4

Periodontal disease accompany the inflammation around periodontal tissue and generally periodontal destruction is followed, This destruction often makes the molar teeth have furcation defect. And to treat molar furcation involvement, resective surgery such as root resection and ostectomy and regenerative procedure such as guided tissue regeneration were introduced. Also implant can be considered as one of the good treatment methods, Among these treatment alternatives, root resection can be considered as a good procedure in the point of saving one's natural teeth or amount of cost. Therefore the purpose of this article is to evaluate root-resected teeth which were done at least 2 years ago. 70 root-resected teeth in 58 patient who visited Kyungpook National University Hospital were included in this study. They were evaluated by two clinical method. One is subjective evaluation and another is objective evaluation. To evaluate subjective outcome, 58 patients answered to the questionnaire if they experienced tooth extraction, bleeding, swelling, pain, mobility and chewing problem. To evaluate objective outcome, 28 teeth was evaluated according to Langer's criteria. The subjective result showed 82% of success rate and 18% of failure rate. 13 of 70 teeth showed discomfort and were considered as failure, which include chewing problem (39%) and pain (23%). The objective outcome showed that 4 failure (14% failure rate) which were 2 cases of bone loss by periodontal problem, one endodontic problem and one untreatable caries. By these limited results, some of clinical consideration in root resective procedure can be suggested. Periodontal support and less occlusal loading on resected tooth should be evaluated before the procedure, moreover, good oral hygiene is essential. When these factors are considered carefully, the root resection may produce predictive outcomes in the treatment of furcational involvement.

준설매립지반의 지지력 산정

이충호,김주현,채영수,이송,Lee, Choong-Ho,Kim, Ju-Hyun,Chae, Young-Su,Lee, Song (사)한국토질및기초기술사회 2006 기술발표회 Vol.2006 No.-

In this test, there was two dimensional model loading test implemented for analysis with respect to the problem of evaluating bearing capacity and the application range on the dredged and reclaimed ground. It was got following conclusion through comparison of button's and Brown&Meyerhof"s equation with experimental result that was obtained by 2 dimensions model loading test. For the difference between average undrained shear strength by 2/3B of loading board width and under 2/3B is more than ${\pm}$ 50%, application of Nc(coefficient of bearing capacity was used in that case $\phi$=0 analysis is considered in the single layer) was declined. Brown&Meyerhof(1969)'s equation was underestimated comparing with loading test result, while Button(1953)'s equation was overestimated comparing with loading test result applied dividing as double layers of upper dessication layer and lower soft layer about dredged and reclaimed ground. Also, bearing capacity factors, Nc that was calculated by using button's equation was estimated greatly about 1.7 times more than bearing capacity factors, Nc that was calculated by using Brown&Meyerhof's equation. Bearing capacity factors, Nc that was calcuated by using Brown&Meyerhof's and Button's equation was evaluated each 2.3-3.6 times, 1.3-2.1 times smaller than bearing capacity factors, Nc5.14 that was calcuated by using Meyerhof's equation in case of unit layer.

백서두개골 결손부에서 천연물유래 탄산칼슘염 골대체의 골치유에 관한 조직계측학적 평가

이충호,장제희,이재목,서조영,박진우,Lee, Chung-Ho,Jang, Je-Hee,Lee, Jae-Mok,Suh, Jo-Young,Park, Jin-Woo 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.1

Purpose: This study investigated the osteoconductivity of natural calcium carbonate-derived bone substitutes, hen eggshell (ES), and compared with those of commercial bone substitutes. Materials and Methods: Osseous defects created in the rat calvaria were filled with particulated ES(ES-1), ES with calcium-deficient hydroxyapatite surface layer (ES-2), Biocoral(Inoteb, France), and Bio-Oss(Geistlich Pharma, Wolhusen, Switzerland). After 4 and 8 weeks of healing, histomorphometic analysis was performed to evaluate the amount of newly formed mineralized bone area (NB%). Results: Histologic and histomorphometric analysis showed new bone formation and direct bony contact with the grafted materials in all groups. At 4 weeks, Biocoral group showed greater NB% compared to Bio-Oss and ES-1 groups (P<0.05). At 8 weeks, Biocoral and ES-2 groups showed significantly greater NB% compared to Bio-Oss group (P<0.05). Conclusion: These results indicate that natural calcium carbonate-derived bone substitutes with microporous calcium-deficient hydroxyapatite surface layer may be an effective materials treating osseous defects.

u-GIS 공간정보 기술 동향

이충호,안경환,이문수,김주완,Lee, Chung-Ho,An, Gyeong-Hwan,Lee, Mun-Su,Kim, Ju-Wan 한국전자통신연구원 2007 전자통신동향분석 Vol.22 No.3

최근 정보통신기술의 발달로 인해 다양한 종류의 컴퓨터가 사람, 사물, 환경 속으로 스며들고, 이들이 서로 네트워크로 연결되어 인간의 삶을 도와주는 유비쿼터스 환경이 급속히 진전되고 있다. 이러한 유비쿼터스 환경은 모두 국토 공간을 근간으로 구현되고 있으며, 국토에 대한 공간 및 위치 정보를 제공하는 u-GIS 공간정보 기술은 미래 유비쿼터스 환경의 핵심 기반 기술로 대두되고 있다. 본 고에서는 u-GIS 공간정보 기술을 구성하는 핵심 기술인 GeoSensor와 GIS 데이터 처리 기술, u-GIS 통합정보 처리기술과 모바일 GeoSensing 기술을 중심으로 최신 동향 및 이슈들을 소개하고, 향후연구 개발 방향을 제시해 보고자 한다.