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확장 가능한 고가용 데이터베이스 클러스터에서 B<sup>+</sup> 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.
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.
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.
李忠鎬 부산여자대학 1989 釜山女子專門大學 論文集 Vol.11 No.-
In this paper, Hangeul character recognition system using single -layer neural nets is proposed and simulated. The system splits an input character into horizontal and vertical segments without any preprocessing such as thinning algorithm, and extracts the positional information of segments. Through the inner-processing of Assembly and normalization, The system recognizes Hangeul characters by using the SLN and comparing with the prototype patterns which have been trained in SLN, and can makes strong decision for multicategory unknown input Hangeul characters with few training patterns.
李忠鎬 충주대학교 1997 한국교통대학교 논문집 Vol.32 No.2
The aim of this research is to investigate the influence of sodium chloride on the volume resistivity characteristics of tranformer oils in temprature range of 20~100[℃]. The geometical capacitance of electrode with coaxial cylindrical shape for measuring the volume resistivity was 16[PF], and highmegaohm meter model VMG-1000 was used, the applying voltage were DC 100 ,250,500 and 1000[v]. The classification for the physical properties of specimen of specimen by FTIR spectroscopy was carried out. As a result of expriment, the value for volume resistivity inreased with sodium chloride contents.
不平等電界內의 棒日板電極間의 코로나 開始와 絶綠破壤에 關하여
李忠鎬 忠州大學校 1985 한국교통대학교 논문집 Vol.18 No.2
Corona inception and breakdown behaviour was investigated for hemispherically capped rod-to-plane gaps in air with insulating supports using 60㎐ ac Voltage. The effect of a series airgap, between the rod and the insulating surface, on Corona inception and breakdown processes was also studied. With epoxy resin insulator, Corona inception Voltag was found to decrease significantly, Where as breakdown voltage increased considerably. The corona inception characteristic was found to exhibit a maxmum at a certain value of the series air gap. Accumulation of charge on the insulating surface seems to play a significant role in corona inception and breakdown phenomena.
Microprocessor을 이용한 인버터의 비동기-동기방식 PWM변조에 관한 연구
李忠鎬,劉鐘哲 충주대 산업과학기술연구소 1993 産業科學論文集 Vol.1 No.-
As industry grow up, induction motor need to be controlled at wide speed range. Whether carrier signal is synchronized to frequency signal or not, the PWM method is classified into asynchronized and synchronized one. In general, the former is easy to realization but generates sub-harmonics and the latrer is difficult, In order to drive from very low speed to high speed with a power device operating frequency concepts, both must de untilized. Output and reference voltage of inverter must be linear to control induction motor high characteristice. This study is discussed about the pulse width modulation and characteristice.
이충호 조선대학교 지역사회발전연구원 2003 地域發展硏究 Vol.8 No.1
Processing trade on consignment will pave the way for the both Koreas' economic cooperation, benefit and prosperity. But problem of successful processing on consignment is export competitiveness. We have to resolve the problem of unclear North Korea. It is important for us to improve north korea and America relationship. After improving their relationship. USA will remove tariff barriers and non-tariff barriers. We can export competitiveness at that time. Now, We have more export competitiveness in Japan market than America market. Processing trade on consignment will give both Koreas synergy effects and mutual benefit. We must prepare for unification times with South and North Korea economic community. The problem of unification is only ours.