• Journal of KIISE:Information Networking
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• v.28 no.2
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• pp.217-228
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• 2001

무선 통신 기술 및 이동 컴퓨터의 성능의 발전함에 따라 이동 컴퓨팅 환경을 단순한 단말기로 사용하기 보다는 독립된 수행 단위로 이용하려는 연구가 활발히 진행되고 있다. 즉 모든 작업을 서버에게 보내어 결과를 기다리는 대신 이동 컴퓨터에서 직접수행할 수 있는 알고리즘이 개발되고 있다. 본 논문에서는 이동 컴퓨터에서의 트랜잭션 수행 알고리즘을 제안한다. 우리는 낙관적인 기법을 채택하였는데 이기법은 (a) 동기화에 필요한 메시지를 적게 필요로 하며 (b) 브로드캐스트 기법의 장점을 얻을수 있다. 브로드캐스트 기법은 최근 많은 수의 클라이언트에게 정보를 전송할 수 있는 수단으로써 많이 연구되고 있다. 그러나 접근하는 데이터간에 충돌이 빈번하게 발생한다면 낙관적 기법은 결국 높은 철회율을 보이게 되며 이는 다시 이동 컴퓨터 자원으로 효율적으로 사용하려는 목적과 반대 결과가 된다. 본 논문에서는 이러한 높은 철회율을 감소시키기 위해 재순서화 개념을 도입하였다. 즉 충돌이 발견될 경우 데이터의 일관성을 침해하지 않는 범위내에서 충돌 순서를 결정하도록 하는 것이다. 특히 읽기-쓰기 트랜잭션에 대해서는 후위-재순서화 개념을 읽기-전용 트랜잭션에 대해서는 전위-재순화 개념(O-Pre)을 제안하였으며 실험에 의하여 성능 향상을 보였다.

• Journal of KIISE
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• v.42 no.1
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• pp.130-137
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• 2015

With the rapid increase of energy consumption and environmental problems, the need for green techniques is increasing. Network coding can provide a solution by reducing unnecessary data transmission and by estimating traffic patterns. In addition, it can amplify the synergy with the cognitive radio network (CR) since the CR has recognition and optimal decision functionalities. In this paper, we propose a network coding based green cognitive radio network. With the simulations, we show that the proposed scheme is up to 25% better than the previous work.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.6
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• pp.674-685
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• 1999

MIDAS-II는 한국전자통신연구원에서 개발한 바다 DBMS의 저장 시스템이다. MIDAS-II 볼륨은 데이터의 논리적 저장 단위인 파일을 저장하는 영역을 가리킨다. 본 논문에서는, MIDAS-II가 대용량 멀티미디어 데이터 서버의 저장 시스템으로 기능하도록 광 디스크 쥬크박스 또는 테이프 라이브러리와 같이 복수 개의 저장 매체 (platter , 예를 들어 디스크 또는 카트리지 테이프)로 구성된 Tera 바이트 급의 3창 저장 장치를 장착할 경우 이를 위한 볼륨 구조의 설계 및 구현에 대해 기술한다. 본 논문에서 제안하는 볼륨 구조는 3차 저장 장치 접근 시 성능 제고를 위하여 디스크 캐쉬 영역을 두고 있으며, 3차 저장 장치의 저장 매체별 관리 기능을 제공한다. Abstract MIDAS-II is the storage systemfor BADA DBMS developed at ETRI. A volume of MIDAS-II is the area where the files, the logical unit for storing data, are stored. This paaper describes the design and implementation of a new MIDAS-II volume structure for the tertiary storage device such as an optical disk juke box or a tape library equipped with multiple platters(disks or cartridge tapes, for example ). Incorporating thetertirary storage device of the order of tera bytes into MIDAS-II enables it to function as a storage system for a massive amount fo multimedia eata server. The volume structure for the tertiary storage device proposed in this paper features disk caching for performing improvement and direct control of theindividual platter.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.169-175
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• 2021

The lot sizing problem(LSP) is a hard problem that classified as non-deterministic(NP)-complete because of the polynomial-time optimal solution algorithm is unknown yet. The well-known W-W algorithm can be obtain the solution within polynomial-time, but this algorithm is a very complex, therefore the heuristic approximated S-M algorithm is suggested. This paper suggests O(n) linear-time complexity algorithm that can be find not the approximated but optimal solution. This algorithm determines the lot size Xt∗ in period t to the sum of the demands of interval [t,t+k], the period t+k is determined by the holding cost will not exceed setup cost of t+k period. As a result of various experimental data, this algorithm finds the optimal solution about whole data.

• Journal of Engineering Education Research
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• v.25 no.3
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• pp.35-44
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• 2022

Artificial intelligence is a core technology in the era of digital transformation, and as the technology level is advanced and used in various industries, its influence is growing in various fields, including social, ethical and legal issues. Therefore, it is time to raise social awareness on ethics of artificial intelligence as a prevention measure as well as improvement of laws and institutional systems related to artificial intelligence development. In this study, we analyzed unstructured data, typically text, such as online news articles and comments to confirm the degree of social awareness on ethics of artificial intelligence development. The analysis showed that the public intended to concentrate on specific issues such as "Human," "Robot," and "President" in 2018 to 2019, while the public has been interested in the use of personal information and gender conflics in 2020 to 2021.

• Journal of Advanced Technology Convergence
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• v.2 no.3
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• pp.1-7
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• 2023

The problem of climate change is intensifying around the world, and the increasing use of fossil fuels is causing a variety of problems. In particular, interest in renewable energy is increasing due to the acceleration of carbon neutrality policies. In this study, we utilized SCOPUS DB to identify trends in renewable energy research. We obtained 1,353 data for which abstracts were available and performed data preprocessing to analyze them. Topic modeling analysis showed that renewable and energy were the most important keywords. In addition, electricity, solar, wind, etc. were analyzed as important keywords. Through the results of this study, it is expected that practitioners of renewable energy-related companies can utilize the research trends related to renewable energy in practice.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.4
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• pp.789-796
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• 2015

The first phase of architecture design is the field survey of the site and its surroundings. To gather the information there are two methods :the traditional method of an onsite survey, and recently using 3D geometry data and high quality image mapping from online services such as Google Earth. However, the urban condition is fast changing, and information from online services may lack sufficient information. This paper presents the to fast and effective site survey method for urban site using an affordable and fully automated UAV for the architectural design field.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.492-494
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• 2021

The decision tree technique is used as a classification technique in machine learning. However, the decision tree has a problem of consuming a lot of speed or resources due to the problem of overfitting. To solve this problem, there are bagging and boosting techniques. Bagging creates multiple samplings and models them using them, and boosting models the sampled data and adjusts weights to reduce overfitting. In addition, recently, techniques Xgboost have been introduced to improve performance. Therefore, in this paper, we collect wifi signal data for indoor positioning, apply it to the existing method and Xgboost, and perform performance evaluation through it.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.19 no.1
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• pp.19-36
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• 2008

The advantage of ontology leads a new knowledge system through integrating existing knowledge system and descriptive element of the concept. This study based on the advantage of ontology, providing a modeling education ontology that considered educational circumstances and related objects-person, organization, educational resources and so forth. Therefore, this study developed the framework for education ontology that provided link between school library and MLA to practice teaching-learning activity, these characteristics of educational ontology were as follows : the first, utilizing the existing education metadata and ontology, the second, representing a concept of educational ontology, subsequently defining classes and properties of education domain, the third, adding new classes and properties to connect existing classes and properties.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.147-148
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• 2022

Recently, as a number of accidents occur while berthing ships, the need for safety measures for ship operation in ports is emphasized. In order to quantitatively analyze the contents of safety measures in Busan New Port, this study collected ship trajectory data,, and based on this data, applied a maritime artificial intelligence algorithm to analyze the trajectory pattern. As a result, the waypoint of the ship arriving and departing Busan New Port was derived and the operation pattern of the ship's speed and course was proposed.