Physical/mechanical properties and microstructure of dental lithium disilicate ceramics for chairside CAD/CAM restoration

학위논문 (박사)-- 서울대학교 대학원 : 치의학과, 2014. 2. 손호현.1. 목적 최근 한번의 내원으로 심미적 수복치료를 완료할 수 있는 CAD/CAM을 이용한 수복에 대한 관심이 늘고 있다. 본 연구의 목적은 두 가지 상용화된 CAD/CAM용 리튬다이실리케이트 세라믹의 물리/기계적 특성을 비교하고 결정의 미세 구조를 관찰하는 것이다. 2. 재료 및 방법 IPS e.max CAD (Ivoclar Vivadent)와 Rosetta SM (Hass)의 초음파 탄성 계수 (n=5), 이축 굴곡 강도 (n=30), 표면 경도 (n=10), 파괴 인성 (n=3), 열팽창 계수 (n=2)를 측정하여 비교하고, 결정의 미세구조를 관찰하기 위해 전계 방출 주사 전자 현미경 촬영과 X선 회절 분석을 하였다. 이축 굴곡 강도와 표면 경도의 평균값 분석을 위해 이원분산분석을 시행하였다. 이후 이축 굴곡 강도는 주효과를 분석하기 위해 Students t-test를 사용하였으며, 표면 경도는 사후 분석을 위해 Tukey HDS를 사용하였다. 탄성 계수와 파괴 인성의 평균값 분석에는 열처리에 따른 차이 분석을 위해 Wilcoxon signed rank test 를 사용하였으며, 재료에 따른 차이를 분석하기 위해 Mann-Whitney U test를 사용하였다. 파괴 인성의 평균값 분석을 위해 Mann-Whitney U test를 사용하였다 (α = 0.05). 3. 결과 초음파 탄성 계수는 열처리 전후 모두 IPS e.max CAD가 Rosetta SM보다 통계적으로 유의한 수준으로 높은 수치를 나타냈다. 굴곡 강도는 열처리 전과 후에서 두 재료 사이에 통계적으로 유의한 차이가 없었으나, 열처리 전, 후의 비교에서는 두 재료 모두 통계적으로 유의한 수준으로 증가하였다. 표면 경도 측정값은 IPS e.max CAD의 경우 열처리 후 유의하게 줄어들었으며, 반대로 Rosetta SM은 증가하였다. 두 재료를 비교하면 열처리 전에는 IPS e.max CAD가 높게 나타났고, 열처리 후에는 Rosetta SM이 높게 나타났다. 이를 토대로 구한 파괴 인성 평균값은 두 재료 모두 열처리 후 현저히 증가됨을 볼 수 있었으며, IPS e.max CAD가 약간씩 높은 값을 나타냈으나 통계적 의미를 찾기는 어려웠다. 전계 방출 주사 전자 현미경과 엑스선 회절 분석 결과 두 제품의 결정의 종류나 형태는 유사하였으나 크기는 열처리 후에 Rosetta SM이 조금 더 작고 조밀한 모습이었다. 이러한 결과에 기초하여 임상가들은 진료실에서 CAD/CAM을 사용한 리튬 다이실리케이트 글라스 세라믹 수복물을 제작할 때 재료 선택의 폭을 늘릴 수 있을 것이라 기대된다.서론 1 재료 및 방법 재료 및 시편 제작 6 실험 방법 1) 초음파 탄성 계수 측정 7 2) 이축 굴곡 강도 측정 8 3) 표면 경도 측정 9 4) 파괴 인성 측정 10 5) 전계 방출 주사 전자 현미경 관찰 10 6) 엑스선 회절 분석 10 7) 열팽창 계수 측정 11 8) 통계 분석 11 결과 12 총괄 및 고찰 16 결론 20 참고문헌 21 Abstract 26Docto

A Solution Methodology for DistributedInformation System Configuration Problem Simultaneously Considering File Allocation and Computer Location Assignment

We have undertaken to develop an efficient solution methodology to adress distributed information system configuration problems through mathematical programming. We have simultaneously considered file allocation and computer location assignment problems which are two aspects of the design tighly coupled in a distributed computer system. A model for solving the problem is shown to be a class of nonlinearinteger programming problems and procedures are developed for computing its lower bound. A heuristic algorithm is also developed and some results are obtained. Numerical results yield practical low cost solutions with substantial savings in computer processing time

An Efficient Workflow Management Scheme with Explicit Business Rules

In this paper, we have identified and classified various workflow operational rules. There are many business rules involved in the operation of workflow systems within the enterprise business environments. The rules are defined as ECA (Event-Condition- Action) rules and integrated with workflow systems with the active DB technology. Operational rules are categorized into task dispatching rules, dynamic process adaptation rules, exception handling rules, event-based monitoring rules, and external domain business rules. By adopting rule-based approach, the modification of business rules for process management can be easier. With the explicit management of business rules, the reasoning process of organizations can be formalized and managed transparently, which enables rapid and clear decision-making

Resource Allocation Algorithm for Differentiated Multimedia Services Using Game Theory

본 논문은 2008년도 한국경영과학회 추계학술대회 경쟁부문(이론) 수상논문으로 소정의 심사과정을 거쳐 게재 추천되었음.Game theory is adapted to a variety of domains such as economics, biology, engineering, political science, computer science, and philosophy in order to analyze economic behaviors. This research is an application of game theory to wireless communication. In particular, in terms of bargaining game we dealt with a multimedia resource allocation problem in wireless communication, which is rapidly spreading such as Wibro, WCDML, IPTV, etc. The algorithm is assumed to allocate multimedia resources to users who can choose and access differentiated media services. For this purpose, a utility function of users is devised to reflect quality of service (QoS) and price. We illustrated experimental results with synthesis data which were made to mimic real multimedia data, and analyzed differentiated service providing and the effect of the utility function.본 연구는 지식경제부 및 정보통신 연구진흥원의 IT원천기술개발사업(IITA-2008-F-005-01)의 지원으로 수행되었음

A Rich Web Search Mechanism using Linkage Information

기존의 웹 검색 시스템은 주어진 키워드들을 모두 포함한 웹 페이지의 도출을 목표로 하기 때문에, 검 색어의 popularity가 떨어지는 경우나, 키워드의 한정 정도가 과도하거나 많아지는 경우, 또는 키워드가 길 어지는 경우 등에는 검색결과가 크게 줄어드는 결과희소성 문제(scarcity problem)를 겪게 된다. 본 연구에 서는 이를 해결하기 위해서 검색결과를 개별 웹페이지 집합이 아닌 관련 웹페이지들간의 링크 구조로 도 출해주는 확장된 검색 방법을 제시한다. 확장된 웹 검색은 링크기반 분석을 활용하여 개별 질의들에 대 한 검색 결과 페이지들간의 링크 관계를 탐색하고, 도출된 검색 결과의 순위 측정을 통해 이루어진다. 본 연구에서 제안하는 확장된 웹 검색 방법은 결과희소성 문제에 효과적임을 보였다

다중분류 문제를 위한 이질적 앙상블 학습

학위논문 (박사)-- 서울대학교 대학원 : 산업공학과, 2015. 8. 조성준.In data mining, classification is a type of supervised learning task that involves predicting output variables consisting of a finite number of categories called classes. When the number of classes is larger than two, a classification problem is called a multi-class classification problem. Multi-class classification provides more informative predictions, and is more related to real-world scenarios. In practice, the performance for a multi-class classification problem is typically measured according to the following three perspectives: accurate, reliable, and fast classification. In order to achieve the better performance for the three perspectives, this dissertation proposes to use heterogeneous ensemble learning that exploits multiple classifiers from various classification algorithms, where each classifier plays a different role to accomplish the desired functionality. For accurate multi-class classification, Diversified One-Against-One (DOAO) and Optimally Diversified One-Against-One (ODOAO) are proposed. Their main idea is to decompose the original problem into several binary sub-problems based on the one-against-one approach. DOAO finds the best classification algorithm for each class pair from the set of heterogeneous base classifiers, thereby makes various classification algorithms to complement each other. Since the best classification algorithm for each class pair is different, DOAO enables better classification accuracy. ODOAO, an extension of DOAO, construct an ensemble where a meta-classifier effectively combines the outputs from all the heterogeneous base classifiers. Heterogeneous Ensemble of One-class Classifiers (HEOC) is also proposed for accurate classification based on decomposition of the original problem into several one-class sub-problems. HEOC constructs an ensemble consisting of one-class classifiers from various one-class classification algorithms. HEOC addresses the normalization of heterogeneous base classifiers via stacking. For reliable multi-class classification, a hybrid reject option is proposed to reject ambiguous instances instead of predicting for all instances. The hybrid reject option constructs a filter classifier and a predictor classifier separately, where the filter decides whether to predict using the predictor based on the confidence for an instance, and the predictor predicts the class of the instance. Each component is trained using the best respective classification algorithm to maximize the capability of its role, thereby improve reject option performance as providing better prediction accuracy for the same degree of rejection. For fast multi-class classification, Neural Network Approximator (NNA) is proposed to reduce computational time in the test phase. NNA approximates a classifier by adopting a multiple-outputs artificial neural network as a function approximator, where each output node corresponds to a decision function in the classifier. This approximator enables fast classification speed without compromising accuracy. The effectiveness of the proposed heterogeneous ensemble methods is demonstrated through experiments on benchmark datasets and real-world applications.1. Introduction 2. Literature Review 3. Heterogeneous Ensemble for Accurate Classification: Binary Classifier Approach 4. Heterogeneous Ensemble for Accurate Classification: One-class Classifier Approach 5. Heterogeneous Ensemble for Reliable Classification 6. Heterogeneous Ensemble for Fast Classification 7. ConclusionDocto

Syntheses, Structures and Properties of Novel Discotic Liquid Crystals

Docto

정수계획법을 이용한 프로젝트 확장순서결정에 관한 연구

Planning for the expansion of production capacity is of vital importance in many applications within the private and public sectors. This paper considers a sequencing expansion problem in which capacity can be added only at discrete points in time. Given the demand forecast of each period, capacity and cost of each expansion project, we are to determine the sequence of expansion necessary to provide sufficient capacity to meet the demand in all periods at minimum cost. This problem is formulated as a pure integer programming and solved by branch and bound method using Lagrangian relaxation. At first. simple sequencing expansion problem is presented, and in the latter part, extension to include precedence between projects is suggested

Studies on the intracellular distribution of myocardial catecholamines of normal animals

의학과/석사[한글] [영문] Accumulated evidence indicates that the catecholamines are stored as granule within the celles of adrenal medulla or sympathetic nervous tissues. Myocardial catecholmines have been shown to be present in the particulate fraction as well as in the soluble fraction obtained by differential centrifugation of cell free suspension from homogenates of cardiac muscle (Potter and Axelrod, 1962; Wegman and Kako, 1962; Campos Shideman, 1962). Howere, according to these investigatore the ratio to that in the soluble fraction of myocardium varies considerably. This may be attributed to a species and fraction procedure difference. Present experiment was designed to determine the intracellular distribution of myocardial catecholamines, with special reference to the animal species. The heart was rapidly removed from animals under ether anesthesia and 5 volumes of 0.38 M ice-cold sucose in a waring blender. The resultant suspension was passed through a double layer of gauze to remove the fibrous tissue. The homogenate was then centrifuged at 3-5℃ for 10 minutes at 600 xg (low-speed centrifugation), which brought down incompletely fragmented cells and nucli. A low-speed supernatant was thus obtained, and was again centrifuged at 3-5℃ for 30 minutes at 15,000 xg (high-speed centrifugation), which fractionated into supernatant and sediment. The concentration of catecholamines in each fraction obtained by the above differential centrifugation, was determined spectrophotofluormetrically by the modified procedure of the method described by Shore and Olin (1958). 1. Examination of the intracellular distribution of the myocardial catecholamines of normal rabbits showed that a higher concentration of the aminos was present in the high-speed supernatant fraction (0.40ug/gm) and the ratio of supernatant/sediment was 4. The catecholamines present in the low-speed supernatant was almost completely recovered in both fractions obtained by high-speed centrifugation. 2. In the cardiac homogenate of normal cats, a similar intracellular distribution of catecholamines was observed. Thus, the concentrations of amines in high-speed supernatant and sediment were 0.48 and 0.09ug/gm respectively. 3.In the experiment with cardiac homogenate of normal rate, it was also found that higher concentration of catecholamines was present in the high-speed supernatant and the ratio of supernatant/sediment was 4.3 which was not significantly different from those observed in the cardiac homogenates of normal rabbits or cats. The concentrations of catecholamines in the high-speed supernatant and sediment fractions would not represent the actual distribution in vivo. However, these values are reproducible and relatively constant under the described experimental conditions. Therefore, these may be considered useful as a criteria for the study of intracellular distribution of myocardial catecholamines. From the above results, it may be concluded that there is no significant difference in the intracellular distribution of myocardial catecholamines of normal rabbits, cats and rats.restrictio

기업간 협업 지원을 위한 XML 문서 메타모델

본 논문은 기업간(B2B) 협업 지원을 위한 객체지향적 XML(eXtensible Markup Language) 문서 메타모델을 제안한다. 분산된 기업들은 제조 정보를 공유하거나, 거래 정보를 교환하면서 협업을 수행한다. 그런데, 일반적으로 각 기업은 자사 고유의 데이터 포맷, 통신 수단, 데이터베이스 구조 등을 보유하고 있다. 따라서 분산된 기업간에 효과적인 협업을 수행하기 위해서는 이질적인 정보 원천들을 용이하게 결합시켜줄 수 있는 기술이 필요하다. 교환되는 데이터를 자동으로 해석하여 기존 레거시 데이터베이스에 저장하는 기술은 기업간 협업을 효과적으로 달성하게 해 주는 기반 기술이 될 것이다. 본 논문은 기업간 데이터 교환의 주요 수단으로 자리잡고 있는 XML 형태의 문서를 데이터베이스에 저장할 수 있는 방법을 제시하고자 한다. 기업간 협업 과정에서 교환되는 문서 유형을 분석하고, XML Schema 메타모델을 대상으로 모든 유형들을 지원할 수 있는 XML문서 모델링 규칙들을 제안한다