• 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.

• 한국안전학회지
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• 제30권4호
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• pp.128-134
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• 2015

The number of schools which have passed 30 years after the construction takes up 30% (5% falling to class D and E) in Korea. So, the offices of education across the nation conduct large works for the expansion, improvement and renovation of the school. But as the work takes a lot of time, the work is also conducted while the students are studying at the schools. The work at the school causes the noise, dust, vibration as the school often has the reinforced concrete structure. So, as the windows are closed to prevent the nuisance from hampering the education, the problems related to the illumination, ventilation, and control of humidity and temperature are give damages to students studying the school buildings. Actually, as the current renovation or expansion is conducted across the nation due to the implementation of the new education system and the resulting integration and construction of hub school, specialized school, meister school and it causes a lot of nuisance to the learning students and others, there are a lot of complaints from concerned people. Accordingly this study suggests the method of evaluating the factors which affect the learning environment such as the noise, dust or fine dust and reducing the nuisances to the level proper for the learning environment when the existing school is expanded, improved or renovated.

• 한국항공우주학회지
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• 제35권10호
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• pp.891-898
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• 2007

피치 제어형 수평축 풍력터빈에 대한 공력최적 설계 형상과 피치 변화에 따른 공력 성능 특성을 수치적으로 계산하였다. 수치적 방법은 날개 요소이론을 적용하였으며, Prandtl의 팁 손실 효과, 에어포일의 분포 효과, 후류의 회전 효과 등을 고려하였다. 블레이드 설계에는 총 6개의 서로 다른 에어포일을 사용하였으며, 구조적 강성을 갖기 위해서 허브 측에는 최대 40% 두께비의 에어포일을 분포시켰다. 최적 설계에서 얻어진 비선형 코드 길이는 제작성과 무게 등을 고려하여 선형화 시켰고, 선형화에 따른 공력성능 변화는 무시할만하다는 결과를 얻어내었다. 피치각 변화에 따른 동력성능, 추력성능, 토크 성능 곡선을 비교한 결과 $3^{\circ}$의 피치각 변화에도 민감한 공력 값의 변동이 생김을 알 수 있었고, 정밀한 피치 제어를 위한 각도 제어는 증분이 $3^{\circ}$보다 작은 값으로 피치 제어 알고리즘과 피치 구동 장치가 필요함을 알 수 있었다. 또한 최대 토크는 설계속도비보다 작은 속도비에서 발생되는 결과를 보여주었다.

• 한국항공우주학회지
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• 제35권2호
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• pp.124-129
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• 2007

동 연구에서는 전진비행하는 로터의 평균 유입류 예측기법 중 Drees 선형모델, 몇가지 변형된 형태의 Mangler & Squire 모델을 서로 비교하여 각 유입류 모델의 특성을 알아내고, KARI 자체 자유후류기법 코드의 해석결과를 함께 비교하여 각 유입류 예측기법의 특성을 파악하였다. 각 예측기법의 비교를 위해 유입류 실험치가 존재하는 로터에 대하여 전진비 0.15, 0.23 및 0.30의 3가지 비행조건을 적용하여 예측한 결과를 비교 분석하였다. Drees 모델의 경우 비교적 실험치에 근접하게 예측하나, 선형모델의 한계로 인해 유입류의 비균일성을 모델링하기에는 미흡하며, Mangler & Squire 모델은 끝단을 제외하고는 비교적 실험치에 근접하게 예측함을 알 수 있었으며, KARI의 자유후류기법은 유입류의 비균일성을 매우 잘 예측하나, 동체에 의한 올려흐름 효과, 후퇴부에서의 동적실속 효과 등의 추가 고려가 필요함을 알 수 있었다.

• 한국산학기술학회논문지
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• 제21권5호
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• pp.664-671
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• 2020

스마트 빌딩 (Smart Building)은 사물 인터넷 (IoT; Internet of Things) 장치와 클라우드 서비스에서 모두 사용될 수 있는 응응 프로그램을 의미한다. 최근 Amazon, Google 및 Microsoft와 같은 클라우드 서비스 제공 업체는 IoT 장치에서 클라우드 애플리케이션 서비스를 제공할 수 있는 IoT 클라우드 플랫폼을 제공하고 있다. Postscapes에 따르면 최근에 152 개의 IoT 클라우드 플랫폼이 존재하고 있으며 스마트 빌딩 구현을 위해 하나를 선택하는 것은 어려운 문제이다. 본 논문에서는 실험을 위해서 마이크로소프트 Azure IoT 허브와 아마존의 AWS(Amazon Web Services) IoT를 선택하였다. 두 개의 IoT 클라우드 플랫폼을 선택하고 스마트 빌딩 관점에서 평가하였다. IoT 클라우드 플랫폼을 평가하기 위해 두 가지 다른 IoT 클라우드 플랫폼을 활용하였고, 일반적인 스마트 빌딩 시나리오를 가정하여 프로토타입을 구현하였다. 실험은 IoT 클라우드 플랫폼을 사용하여 시스템을 개발하는 과정에서 얻은 정보와 경험을 기반으로 수행하였다. 이 평가 결과는 스마트 빌딩을 위해 IoT 클라우드 플랫폼을 선택할 때 활용될 수 있다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.3-3
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• 2011

After the dissolution of the Soviet Union, the Kra-Araks Basin (KAB) became an international river basin with respect to the South Caucasus states of Armenia, Azerbaijan, and Georgia. However, there are no agreements regarding water allocation, water quality, or ecosystem maintenance among the aforementioned riparians. The main water problems in the basin include not only water quantity and quality, but also the lack of joint management. The aforementioned countries share many similar circumstances: location in a politically unstable but strategic region bureaucratic and structural issues; and more importantly, ongoing ethnic and related conflicts. Despite these obstacles, the countries recognize that they depend greatly on the basin, whose waters they must share. To that end, they proposed and participated in the joint NATO-OSCE South Caucasus River Monitoring (SCRMP) project between 2002 and 2009.The SCRMP sought to investigate and characterize the surface water quality in the KAB by providing equipment and training to all three countries. Several years' worth of water quality data were collected in the KAB: major ions; heavy metals; POPs (persistent organic pollutants); and radionuclides; The North Atlantic Treaty Organization (primary funder) and the Organization for Security and Co-operation in Europesupported the SCRMP not only to build capacity but also to promote cooperation and minimize conflict over water and other resources, thus providing a measure of security for Europe and other regions. The South Caucasus is a strategically-important region, functioning as a bridge between Asia and Europe. Energy-rich Azerbaijan seeks to become a key player in trade by serving as a transportation and energy hub between the energy and mineral-rich Central Asian KUT countries (Kazakhstan, Uzbekistan, and Turkmenistan) and Western Asia, Europe, and other areas. The presentation will summarize the scientific results of the SCRMP, elucidate the regional water-energy-security nexus, discuss future work in the region, and explain why the world needs to be concerned about the KAB and the entire South Caucasus.

• 한국통신학회논문지
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• 제31권1B호
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• pp.19-25
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• 2006

USB는 여타 다른 입출력 장치보다 더 자주 그리고 널리 사용되는 장치이다. PC시스템으로 보면 USB는 매우 성공적인 인터페이스 기술이다. PC시스템에서는 벌써 널리 사용되고 있을 뿐만 아니라 소비가전과 이동기기에서도 또한 널리 장착되고 있다. 게다가 USB는 이미 설치된 킬러응용프로그램도 매우 많다. 그렇지만 이런 입출력장치들은 유선으로 인해 사용자불편의 문제점을 가지고 있다. 많은 기기에 설치된 USB 장치를 무선화 시킬 수 있다면 유선화로 인한 스트레스를 줄임과 동시에 널리 사용되고 있는 USB의 사용이 더욱 더 편리해질 수 있을 것이다. 본 논문에서는 USB의 기존기능, 이식성, 멀티미디어 능력 등을 그대로 수용하면서 무선화할 수 있는 소프트웨어적인 방법을 연구한다. 본 논문은 이러한 USB의 무선화 구현에 관한 것이다. 이는 특히 기존 USB 호스트 기능에 내장된 USB 루트허브기능, 호스트 기능, ETD(Endpoint Transfer Descriptor), 데이터 메모리관리 등을 소프트웨어 모듈로 구성하여 유선일 때와 마찬가지 성능으로 지연없이 요구사항을 만족시켜야 한다. 무선화와 무선을 통해 그 기능을 어떻게 구현할 것인가에 대한 현안을 살펴보기로 한다. 이러한 구현은 기존의 USB의 편리한 사용과 시장력을 더 가속화할 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.660-665
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• 2006

This paper presents a finite element method to analyze the free and forced vibration of a hard disk drive (HDD) considering the flexibility of a spinning disk-spindle with fluid dynamic bearings (FDBs), an actuator with pivot bearings, an air bearing between head-disk interface and the base with complicated geometry. Finite element equation of each component is consistently derived with the satisfaction of the geometric compatibility of the internal boundary between each component. The spinning disk, hub and FDBs are modeled by annular sector elements, beam elements and stiffness and damping elements, respectively. The actuator am, E-block, suspension and base plate are modeled by tetrahedral elements. The pivot bearing in the actuator and the air bearing between head-disk interfaces are modeled by the stiffness element with five degrees of freedom and the axial stiffness, respectively. A global matrix equation obtained by assembling the finite element equations of each substructure is transformed to a state-space matrix-vector equation, and both damped natural frequencies and modal damping ratios are calculated by solving the associated eigenvalue problem with the restarted Arnoldi iteration method. Modal and shock testing are performed to show that the proposed method well predicts the vibration characteristics of a HDD.

• Mass Spectrometry Letters
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• 제2권1호
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• pp.1-7
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• 2011

China's rapid economic growth has resulted in significant environmental side effects. Therefore, China has been interested in reducing her dependence on foreign oil and gas by developing technologies needed for hydrogen, in addition to her increasing energy mix of nuclear and renewable energy form, such as solar and wind power. There are three isotopes of hydrogen, i.e. protium (P or H), deuterium (D), and tritium (T). Both deuterium and tritium are important materials in nuclear fuel cycle industry. Tritium is one of the critical radioactive nuclides. Planning for and implementing contamination control as a part of normal operation and maintenance activities is an important function in any hydrogen facility, especially tritium facility. The development of hydrogen isotopes analysis is the key issues in this area. Mass spectrometry (MS) with medium (about 600) and high resolution (> 1,400) is commercially available; however, the routine analysis of hydrogen isotopes is done with low-resolution MS (< 200) in China. This paper summarizes the progress of MS measurement technology for hydrogen isotope abundance in China, focusing on our lab's research program and technical status. An analyzing method has been introduced for accurate measurement of tritium abundance in the H.D.T system by low resolution MAT-253 MS. The quotient of compression ratio coefficient is determined by building up equipment for laboratory-scale preparation of secondary standard gases and by considering the difference in sensitivity between hydrogen isotopes. The results show that the measured value is reproducible within the relative error range of 0.8% for gas samples of different tritium abundance.

• 통상정보연구
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• 제15권1호
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• pp.357-379
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• 2013

최근 우리나라는 외화획득용 원료 등 구매제도에 대해 전자화를 도입하게 되었다. 정부는 구매확인서의 전자화를 위해서 2011년에 대외무역관리규정을 개정하였다. 또한, 외화획득용 원료 등 구매제도에는 구매확인서에 이어 2012년에 내국신용장도 전자화하였다. 이는 우리나라 전자무역이 로컬거래 절차의 전자화를 추진하게 되는 것이다. 본 연구에서는 외화획득용 물품관리제도에 대한 선행적 고찰과 대외무역관리규정의 개정을 통한 구매확인서 전자발급의 의무화 및 한국은행 무역금융 취급세칙의 개정으로 내국신용장의 전자개설 의무화에 따른 이론적, 법적 고찰과 로컬거래 절차의 전자화의 추진인로컬거래 통합관리시스템의 구축에 있어 법적, 실무적 문제점과 대응방안을 분석하였다.