• 제목/요약/키워드: complex predicate

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XML 질의처리를 위한 다차원 타입상속 색인구조의 할당기법 (An Assignment Method of Multidimensional Type Inheritance Indexes for XML Query Processing)

  • 이종학
    • 한국멀티미디어학회논문지
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    • 제12권1호
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    • pp.1-15
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    • 2009
  • 본 논문에서는 XML 데이터베이스에서 XML 질의처리를 효율적으로 지원하기 위한 다차원 타입상속 색인구조(MD-TIX)들의 할당기법을 제시한다. MD-TIX는 중첩요소와 여러 타입상속 계층으로 이루어진 중첩술어의 처리를 효율적으로 지원하기 위하여 다차원 색인구조를 이용하는 색인기법이다. 본 논문에서는 타겟 타입 또는 도메인 타입의 대치가 있는 Xpath로 표현된 여러 중첩술어들의 접속으로 구성된 복합질의의 관점에서 MD-TIX 색인들의 할당에 따른 질의처리 기법들을 분석하고, 그 결과로서 가장 효과적인 객인 할당기법을 제시한다. 먼저, XML문서의 변경에 따른 MD-TIX 색인구조의 운용과 하나의 중첩술어를 가지는 질의처리에 대한 MD-TIX 색인의 할당에 대하여 분석한다. 그리고 경로들 사이에 공통의 부경로가 있는 겹침 경로 상에 주어지는 여러 개의 중첩술어들로 구성된 보다 일반적인 질의의 관점에서 MD-TIX 색인의 운용과 그 할당기법을 제시한다.

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객체지향 질의의 효율적 처리를 위한 다차원 경로 색인구조의 최적 구성방법 (Optimal Configurations of Multidimensional Path Indexes for the Efficient Execution of Object-Oriented Queries)

  • 이종학
    • 한국멀티미디어학회논문지
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    • 제7권7호
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    • pp.859-876
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    • 2004
  • 본 논문에서는 객체 데이타베이스에서 객체지향 질의의 효율적 처리를 위한 다차원 경로 색인구조(Multidimensional Path Indexes: MPIs)의 최적 구성방법을 제시한다. MPI는 중포속성과 여러 클래스 계층이 포함된 중포술어를 효율적으로 지원하기 위하여 다차원 색인구조를 이용한다. $B^+$-tree와 같은 일차원 색인구조를 이용한 중포속성 색인구조로서는 이와 같은 술어를 잘 지원할 수 없다. 본 논문에서는 타겟 클래스 또는 도메인 클래스의 대치가 있는 경로식으로 표현된 여러 중포술어들의 접속으로 구성된 복합질의의 관점에서 MPI 색인들의 구성에 관하여 분석한다. 먼저, 데이타베이스의 변경에 따른 MPI 색인구조의 운용과 하나의 중포술어를 가지는 질의의 경우에 대한 MPI 색인의 사용에 대하여 색인구성을 분석한다. 그리고 겹침 경로와 비겹침 경로 상에 주어지는 여러 개의 중포술어들로 구성된 보다 일반적인 질의의 관점에서 MPI 색인의 구성에 관하여 분석한다. 겹침 경로는 경로들 사이에 공통의 부경로가 있는 것이고, 비겹침 경로는 공통의 부경로가 없는 것이다.

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Unified calculation model for the longitudinal fundamental frequency of continuous rigid frame bridge

  • Zhou, Yongjun;Zhao, Yu;Liu, Jiang;Jing, Yuan
    • Structural Engineering and Mechanics
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    • 제77권3호
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    • pp.343-354
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    • 2021
  • The frequencies formulas of the bridge are of great importance in the design process since these formulas provide insight dynamic characteristics of the structure, which guides the designers to parametric analyses and the layout of the bridge in conceptual or preliminary design. Continuous rigid frame bridge is popular in the mountainous area. Mostly, this type of bridge was simplified either as a girder or cantilever when calculating the frequency, however, studies showed that the different configuration of the bridge made the problem more complex, and there is no unified fundamental calculation pattern for this kind of bridge. In this study, an empirical frequency equation is proposed as a function of pier's height, stiffness of pier and the weight of the structure. A unified fundamental frequency formula is presented based on the energy principle, then the typical continuous rigid frame bridge is investigated by finite element method (FEM) to study the dynamic characteristics of the structure, and then several key parameters are investigated on the effect of structural frequency. These parameters include the number, position and stiffness of the tie beam. Nonlinear regression analyses are conducted with a comprehensive statistical study from plenty of engineering structures. Finally, the proposed frequency equation is validated by field test results. The results show that the fundamental frequency of the continuous rigid frame bridge increases more than 15% when the tie beams are set, and it increases with the stiffness ratio of tie beam to pier. The results also show that the presented unified fundamental frequency has an error of 4.6% compared with the measured results. The investigation can predicate the approximate longitudinal fundamental frequency of continuous ridged frame bridge, which can provide reference for the seismic response and dynamic impact factor design of the pier.

주어-동사 일치의 통사적 유인 (Syntactic Attraction of Subject-Verb Agreement)

  • 장소영;김양순
    • 문화기술의 융합
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    • 제7권3호
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    • pp.353-358
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    • 2021
  • 본 연구는 주어-동사 일치에 대한 3가지 유형의 통사적 분석을 제공한다. 주어-동사의 수일치는 주어와 서술어간의 연쇄를 체계적으로 설명하기 때문에 이는 핵-핵 일치 또는 계층적 구조에 작용하는 상방향과 하방향 자질침투라는 순수한 통사적 분석으로 제안되어야 한다. 주어-동사 일치의 오류는 선형적 근접성이나 최소간섭이 아닌 일치의 목표와 국소적 유인자인 명사 사이의 계층적 관계에 의해 영향을 받는다. 본 연구의 자료로 수식어로서의 전치사구 PP 또는 관계절 CP를 포함하는 복합 명사구를 분석하며 이때 복수자질 [+PL]이 강 자질로서 일치오류의 국소 유인자이다. 따라서 일치오류는 화자들이 수식어 전치사구의 복수 명사구 때문에 주절의 단수 주어를 복수로 잘못 분석하거나 복수 주어의 영향으로 수식어 관계절안의 단수 주어가 복수로 잘못 분석되어 관계절 안의 동사가 복수형으로 잘못된 일치 오류가 일어나는 경향이 있다. 즉, 주어-동사 일치는 구조가 형성되는 과정에 내재적으로 불일치하는 일은 없고 특정한 구성소 표현이 국소 유인자로 오인되어 단지 언어분석처리 중에 조작되어 나타난다.

시맨틱 웹 자원의 랭킹을 위한 알고리즘: 클래스중심 접근방법 (A Ranking Algorithm for Semantic Web Resources: A Class-oriented Approach)

  • 노상규;박현정;박진수
    • Asia pacific journal of information systems
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    • 제17권4호
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    • pp.31-59
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    • 2007
  • We frequently use search engines to find relevant information in the Web but still end up with too much information. In order to solve this problem of information overload, ranking algorithms have been applied to various domains. As more information will be available in the future, effectively and efficiently ranking search results will become more critical. In this paper, we propose a ranking algorithm for the Semantic Web resources, specifically RDF resources. Traditionally, the importance of a particular Web page is estimated based on the number of key words found in the page, which is subject to manipulation. In contrast, link analysis methods such as Google's PageRank capitalize on the information which is inherent in the link structure of the Web graph. PageRank considers a certain page highly important if it is referred to by many other pages. The degree of the importance also increases if the importance of the referring pages is high. Kleinberg's algorithm is another link-structure based ranking algorithm for Web pages. Unlike PageRank, Kleinberg's algorithm utilizes two kinds of scores: the authority score and the hub score. If a page has a high authority score, it is an authority on a given topic and many pages refer to it. A page with a high hub score links to many authoritative pages. As mentioned above, the link-structure based ranking method has been playing an essential role in World Wide Web(WWW), and nowadays, many people recognize the effectiveness and efficiency of it. On the other hand, as Resource Description Framework(RDF) data model forms the foundation of the Semantic Web, any information in the Semantic Web can be expressed with RDF graph, making the ranking algorithm for RDF knowledge bases greatly important. The RDF graph consists of nodes and directional links similar to the Web graph. As a result, the link-structure based ranking method seems to be highly applicable to ranking the Semantic Web resources. However, the information space of the Semantic Web is more complex than that of WWW. For instance, WWW can be considered as one huge class, i.e., a collection of Web pages, which has only a recursive property, i.e., a 'refers to' property corresponding to the hyperlinks. However, the Semantic Web encompasses various kinds of classes and properties, and consequently, ranking methods used in WWW should be modified to reflect the complexity of the information space in the Semantic Web. Previous research addressed the ranking problem of query results retrieved from RDF knowledge bases. Mukherjea and Bamba modified Kleinberg's algorithm in order to apply their algorithm to rank the Semantic Web resources. They defined the objectivity score and the subjectivity score of a resource, which correspond to the authority score and the hub score of Kleinberg's, respectively. They concentrated on the diversity of properties and introduced property weights to control the influence of a resource on another resource depending on the characteristic of the property linking the two resources. A node with a high objectivity score becomes the object of many RDF triples, and a node with a high subjectivity score becomes the subject of many RDF triples. They developed several kinds of Semantic Web systems in order to validate their technique and showed some experimental results verifying the applicability of their method to the Semantic Web. Despite their efforts, however, there remained some limitations which they reported in their paper. First, their algorithm is useful only when a Semantic Web system represents most of the knowledge pertaining to a certain domain. In other words, the ratio of links to nodes should be high, or overall resources should be described in detail, to a certain degree for their algorithm to properly work. Second, a Tightly-Knit Community(TKC) effect, the phenomenon that pages which are less important but yet densely connected have higher scores than the ones that are more important but sparsely connected, remains as problematic. Third, a resource may have a high score, not because it is actually important, but simply because it is very common and as a consequence it has many links pointing to it. In this paper, we examine such ranking problems from a novel perspective and propose a new algorithm which can solve the problems under the previous studies. Our proposed method is based on a class-oriented approach. In contrast to the predicate-oriented approach entertained by the previous research, a user, under our approach, determines the weights of a property by comparing its relative significance to the other properties when evaluating the importance of resources in a specific class. This approach stems from the idea that most queries are supposed to find resources belonging to the same class in the Semantic Web, which consists of many heterogeneous classes in RDF Schema. This approach closely reflects the way that people, in the real world, evaluate something, and will turn out to be superior to the predicate-oriented approach for the Semantic Web. Our proposed algorithm can resolve the TKC(Tightly Knit Community) effect, and further can shed lights on other limitations posed by the previous research. In addition, we propose two ways to incorporate data-type properties which have not been employed even in the case when they have some significance on the resource importance. We designed an experiment to show the effectiveness of our proposed algorithm and the validity of ranking results, which was not tried ever in previous research. We also conducted a comprehensive mathematical analysis, which was overlooked in previous research. The mathematical analysis enabled us to simplify the calculation procedure. Finally, we summarize our experimental results and discuss further research issues.