• Title/Summary/Keyword: collection.

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Garbage Collection Technique for Reduction of Migration Overhead and Lifetime Prolongment of NAND Flash Memory (낸드 플래시 메모리의 이주 오버헤드 감소 및 수명연장을 위한 가비지 컬렉션 기법)

  • Hwang, Sang-Ho;Kwak, Jong Wook
    • IEMEK Journal of Embedded Systems and Applications
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    • v.11 no.2
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    • pp.125-134
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    • 2016
  • NAND flash memory has unique characteristics like as 'out-place-update' and limited lifetime compared with traditional storage systems. According to out-of-place update scheme, a number of invalid (or called dead) pages can be generated. In this case, garbage collection is needed to reclaim invalid pages. Because garbage collection results in not only erase operations but also copy operations of valid (or called live) pages to other blocks, many garbage collection techniques have proposed to reduce the overhead and to increase the lifetime of NAND Flash systems. This techniques sometimes select victim blocks including cold data for the wear leveling. However, most of them overlook the cost of selecting victim blocks including cold data. In this paper, we propose a garbage collection technique named CAPi (Cost Age with Proportion of invalid pages). Considering the additional overhead of what to select victim blocks including cold data, CAPi improves the response time in garbage collection and increase the lifetime in memory systems. Additionally, the proposed scheme also improves the efficiency of garbage collection by separating cold data from hot data in valid pages. In experimental evaluation, we showed that CAPi yields up to, at maximum, 73% improvement in lifetime compared with existing garbage collections.

Education for Collection Development : A Study on the Curriculum (장서개발의 교육 : 교과과정의 연구)

  • 엄영애
    • Journal of Korean Library and Information Science Society
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    • v.31 no.3
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    • pp.169-184
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    • 2000
  • The purpose of this paper is to find out how the education for collection development has been changed and what are the contents of the collection development-related courses. The author tried to search some historical backgrounds on how selection of books became collection development and management. As for the ducation for collection development, the changes the course titles dealing with collection development were surveyed, and the contents of the courses provided by the Departments of Library and Information Science were analyzed. It was found out that though the course titles have been changed from selection of materials collection development, the contents showed their emphases on such selection-oriented topics as selection tools and acquisitions. It is concluded that as far as the contents are concerned, most of the important components for collection development have been taught. Based on the findings, a few suggestions including that there should be efforts to narrow the gap between the theories taught at library schools and the practices performed by librarians are recommended.

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Development of Expert-System for Municipal Solid Waste Collection and Transportation (생활 폐기물 수집.수송 관리를 위한 Expert-System 개발)

  • Kang, Dong-Gu;Ryu, Don-Sik;Lee, Hae-Seung;Lee, Chan-Ki
    • Journal of the Korean Society of Hazard Mitigation
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    • v.1 no.1 s.1
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    • pp.91-102
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    • 2001
  • This study aims to provide a program for the municipal solid waste collection and transportation management through data consolidation and field research of the materials about waste collection and transportation in a small city. The field research was conducted in the collection zone of the housing, apartment and business section within C city area. As a result, the main factor of collection and transportation plan required at the waste collection and transportation process and the central mean applying at the small city were calculated. The process that systemize the waste collection and transportation step and the expert system were constructed. In conclusion, the developed management system of the municipal solid waste collection and transportation can be wildly used by adding the data of other zone.

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A Study on the Korean University Library Collection (한국 대학도서관 수서(收書)에 관한 연구)

  • Chun Myung Sook
    • Journal of the Korean Society for Library and Information Science
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    • v.11
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    • pp.77-116
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    • 1984
  • Korean university libraries are increasing their library collection each year according to the standard set by the Ministry of Education. The standard states that all the university libraries are required to keep 3 books for newly enrolling students, 30 books for each enrolled student and 5, 000 books for each department. The increasing number of the university library collection brings many problems in the libraries. 1. The size of the library collection is not related to the satisfaction of the library user's requests. The satisfaction is usually related to number of the new publications received in the library. Z. The Korean publication is limited to a small number. It could not meet the university standard. Therefore, the number is filled with the foreign publications. But the use of them is not frequent. Even the number of the domestic and foreign new publications together could not meet all the requests of the university library users. Only cooperation with other libraries will be able to meet most of the diversified requests. 3. Most of the present library collection are not likely to be used in the future and they should be eventually discarded. Present library administration put too much emphasis on the size of library collection and only the aquisition of the material is main concern of the university librarians. They need to consider other factors in the aquistion of the library collection. They should make their collection development in accordance with user's requests in addition to meet the university standard.

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A Sensing Data Collection Strategy in Software-Defined Mobile-Edge Vehicular Networks (SDMEVN) (소프트웨어 정의 모바일 에지 차량 네트워크(SDMEVN)의 센싱 데이터 수집 전략)

  • Nkenyereye, Lionel;Jang, Jong-Wook
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2018.10a
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    • pp.62-65
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    • 2018
  • This paper comes out with the study on sensing data collection strategy in a Software-Defined Mobile Edge vehicular networking. The two cooperative data dissemination are Direct Vehicular cloud mode and edge cell trajectory prediction decision mode. In direct vehicular cloud, the vehicle observe its neighboring vehicles and sets up vehicular cloud for cooperative sensing data collection, the data collection output can be transmitted from vehicles participating in the cooperative sensing data collection computation to the vehicle on which the sensing data collection request originate through V2V communication. The vehicle on which computation originate will reassemble the computation out-put and send to the closest RSU. The SDMEVN (Software Defined Mobile Edge Vehicular Network) Controller determines how much effort the sensing data collection request requires and calculates the number of RSUs required to support coverage of one RSU to the other. We set up a simulation scenario based on realistic traffic and communication features and demonstrate the scalability of the proposed solution.

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Examining the Collection Management Process in Public Libraries (공공도서관 장서관리 현황 분석)

  • Lee, Jee-Yeon
    • Journal of the Korean Society for Library and Information Science
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    • v.43 no.3
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    • pp.247-267
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    • 2009
  • This study attempted to analyze the collection management process and its requirements for public libraries. The survey was designed to examine the detailed collection management guidelines and to grasp its requirements varying across different types of public libraries. The respondents to the survey were librarians who are responsible for managing collections in public libraries which achieved excellence in the 2008 nationwide library management assessment. The study results indicated that most public libraries do not have organized collection management guidelines covering the whole collection management area. In addition, small libraries such as those in hospitals, armies, and prisons have difficulties in managing collections since they do not have proper collection management guidelines.

Numerical Study on the Flow Characteristics of Uniflow Cyclone (단방향 사이클론의 유동 특성에 관한 수치해석적 연구)

  • Yan, Zheng-Qi;Zhang, Shuo;Shin, Weon Gyu
    • Journal of the Korean Society of Visualization
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    • v.18 no.3
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    • pp.77-83
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    • 2020
  • A uniflow cyclone has simple structure with a single channel in one direction. The one directional particle removal enables the uniflow cyclone to have compact size and low pressure drop. However, it has low collection efficiency compared to conventional cyclones. In this study, the effect of primary geometry on the performance of a uniflow cyclone with swirl vane is numerically investigated for the design of high performance uniflow cyclone. It is found that as the vortex finder diameter is increased, the pressure drop and the collection efficiency are decreased. Also, the same trend is predicted when the vortex finder height is increased. The best collection efficiency is predicted to be obtained when the vortex finder height is equal to the diameter of a cyclone. Reducing the body height by half will increase the pressure drop by 41%. When the body height is decreased, the collection efficiency is first increased and then decreased. The best collection efficiency is obtained when the body height is 4~5 times the cyclone diameter. Overall, the particle collection efficiency is highest when the Dν/D is equal to 0.3. But, the pressure drop is as high as 1592 Pa. Considering both collection efficiency and pressure drop, the best design is when Dν/D, Hν/D, and Hb/D are equal to 0.5, 1, and 5, respectively.

Analysis of Collection and Circulation for Multicultual Libraries and Policy Implications: A Case of Ansan Multicultural Small Library (다문화 밀집지역 작은도서관의 장서 대출 현황 분석과 정책적 시사점 - 안산다문화작은도서관 사례연구 -)

  • Eungyung Park
    • Journal of the Korean BIBLIA Society for library and Information Science
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    • v.34 no.4
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    • pp.77-99
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    • 2023
  • This study aims to quantitatively assess collection and circulation data of one small library in an area where multicultural users are concentrated and draw policy implications on improving multicultural services for public libraries. The Ansan Multicultural Small Library was selected for examining the library's collection and circulation usages from 2016 to 2022. The numbers of collection and circulation, collection turnover rates and use factors were calculated by year, language, and KDC subject. The result of this study presents the empirical evidence drawn from users' circulation usage, which can be a basis for leading to valid collection development and multicultural service policies.

Effect of Particle Loading on the Collection Performance of an Electret Cabin Air Filter for Submicron Particles (입자 퇴적이 승용차용 정전 필터의 미세 입자 포집 특성에 미치는 영향)

  • Ji, Jun-Ho;Gang, Seok-Hun;Hwang, Jeong-Ho;Bae, Gwi-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.8
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    • pp.1102-1114
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    • 2002
  • An electret filter is composed of permanently charged electret fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using poly-disperse particles when submicron particles were loaded. Long-term experiments were conducted by applying two different charging states, which were spray electrification and charge equilibrium by bipolar ionization. In order to investigate the effect of particle loading in filter media, NaCl particles were generated from 0.1% and 1% solutions by an atomizer. Liquid DOS particles were used to evaluate the effect of liquid particles on the collection efficiency of an electret filter. The results show significant effect of charge amount and size distribution of loading particles on the collection performance of a filter media in submicron region. Smaller particles loaded in electret fibers cause a more rapid degradation in collection efficiency and have lower minimum efficiency with time. The pressure drop of a filter media do rarely increase when the collection efficiency decreases to the minimum value. For the larger particles charged by spray electrification, which have charge amounts more than that of Boltzmann equilibrium charge distribution, the pressure drop of a filter media slowly increases in comparison with that of equilibrium charged particles. For DOS particles it is shown that the charging level of an electret filter severely decreases and the collection efficiency is below 10% in some particle size range.

Analysis and Implication of the Collection Development Policy of Public Libraries in Major Cities (대도시 공공도서관 장서개발정책 분석과 제언)

  • Yoon, Hee-Yoon;Kim, Jong-Ae;Oh, Seon-Kyung
    • Journal of the Korean Society for information Management
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    • v.37 no.3
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    • pp.51-75
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    • 2020
  • All public libraries are collection-based knowledge and cultural service institutions. To this end, a collection development policy is an essential and a strategic menu that every library should establish first. Regional central libraries should establish and apply optimal collection development policies to conduct the legal duties as knowledge and information centers and cooperative preservation facilities of the cities and provinces. Thus, this study analyzed and compared in detail the collection development guidelines (draft) and regulations of regional central libraries in Korea and the collection development policies of metropolitan public libraries abroad. Results showed that the policies of domestic regional central libraries were simply practical guidelines while those in most developed countries were substantial in format and content. All regional central library systems should establish and document collection development policies based on the importance of collection development, future-oriented thinking, and strategic decision. The study also suggested the basic principles and the format for this purpose.