• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.924-942
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• 2005

Recently, large-scale directories have been developed for LINUX cluster file systems to store and retrieve huge amount of data. One of them, GFS directory, has attracted much attention because it is based on extendible hashing, one of dynamic hashing techniques, to support fast access to files. One distinctive feature of the GFS directory is the flat structure where all the leaf nodes are located at the same level of the tree. Hut one disadvantage of the mode structure is that the height of the mode tree has to be increased to make the tree flat after a byte is inserted to a full tree which cannot accommodate it. Thus, one byte addition makes the height of the whole mode tree grow, and each data block of the new tree needs one more link access than the old one. Another dynamic hashing technique which can be used for directories is linear hashing and a couple of researches have shown that it can get better performance at file access times than extendible hashing. [n this research, we have designed and implemented an extendible hashing directory and a linear hashing directory for large-scale LINUX cluster file systems and have compared performance between them. We have used the semi-flat structure which is known to have better access performance than the flat structure. According to the results of the performance evaluation, the linear hashing directory has shown slightly better performance at file inserts and accesses in most cases, whereas the extendible hashing directory is somewhat better at space utilization.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.616-619
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• 2004

최근 대용량 데이터의 저장과 검색을 요구하는 파일시스템이 필요하게 됨에 따라, 별도의 서버를 두지 않고 분산된 클라이언트가 메타데이터를 직접 관리하면서 모든 저장 장치들에 접근할 수 있는 SAN 기반 리눅스 클러스터 파일시스템의 연구가 활발하게 진행 중에 있다. 이러한 대규모 파일 시스템을 위해서는 동적 해싱을 이용한 디렉토리 관리가 요구되므로, 본 논문에서는 그 중 확장 해싱 디렉토리 구조와 선형 해싱 디렉토리 구조를 설계 및 구현하고, 구현된 시스템을 이용하여 성능평가를 통해 두 디렉토리 구조의 성능을 분석한다. 비교 분석 결과, 파일의 삽입 성능에서는 선형 해싱 기반의 디렉토리가 우수하였으나, 공간 활용면에서는 확장 해싱 기반의 디렉토리가 우수한 성능을 보였다.

• Survey Research
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• v.9 no.1
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• pp.1-22
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• 2008

Telephone directories ille still being used as the sampling frame in almost all fixed-line telephone surveys in Korea, causing potentially serious coverage error. RDD (random digit dialing) sampling is an obvious alternative to solve the problem. The aim of this paper is twofold: 1) proposal of RDD methodology suitable to the telephone system of Korea and 2) the identification of socio-demographic and socio-psychological differences between listed-number and unlisted-number respondents. Major findings of RDD telephone survey conducted experimental]y are as follows. 1) Population coverage by telephone directories is 60% or less. 2) Unlisted-number households have statistically larger income compared to listed-number households. 3) Unlisted-number households have smaller family size compared to listed-number households. 4) Unlisted-number respondents are more sensitive about confidentiality, leaks, 5) Unlisted-number respondents are more liberal compared to unlisted-number respondents. These facts suggest that directory-based telephone surveys tend to be biased in socio-economic aspects.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.2
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• pp.126-132
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• 2013

This study proposed a method to classify internet websites based on occurrence frequency of medical terms in the webpages and website structure composed with webpages and hyperlinks. The classification was done by using the suitability measure defined by three factors: (1)occurrence frequency of medical terms in the whole terms involved in a webpage, (2)occurrence frequency of medical terms in de-duplicated terms involved in the webpage, and (3)the number of hyperlinks to reach to a specific webpage from homepage. We conducted an experiment to verify the proposed method with the 80 websites registered in directories related to medical field and 127 websites in nonmedical field directories, and the experiment result showed 82.5 % of accuracy of the classification.

• Journal of Information Management
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• v.36 no.4
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• pp.91-115
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• 2005

While the amount of information exchanged through internet has dramatically increased recently, certain inefficiencies still exist with regard to the storage, distribution, and retrieval of information. As a means of improving efficiency in accessing information, many search portals provide directory services to present organized guidance to information, based on the classification schemes. This study examines the classification activities practiced by the major search portals in Korea and makes some suggestions to improve the quality of directory services.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.05a
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• pp.71-72
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• 2007

In this study and design, I explore the visual communication design process related to wayfinding in Wonkwang University Hospital in Iksan City. The purpose for designing an integrated is to graphically communicate the complex information. I have designed a graphic information system combining graphic elements such as typography, color, image and text layout, and graphic image to present interpretive and communicative processes. As a result of designing, the wayfinding is s term used to describe the program of applying environmental graphics and or architectural sign systems. In other words, wayfinding is the art of helping people find their way by utilizing visual communications such as signs, directories, landmarks, edges, paths and so on. Wayfinding can also be explained as the ability to know where one is in space and how to find one's way through space. Wayfinding design then becomes a systematic arrangement of the variables that allows patients and visitors to successfully find their desired destinations, especially in a hospital.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2003.05a
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• pp.3-7
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• 2003

For high performance Grid environments, an efficient GIS(Grid Information Service is required In the Metacomputing Directory Service(MDS) of the Glogus middleware, the Lightweight Directory Access Protocol(LDAP), which is a distributed directory service protocol, is used. The LDAP GIS differs from general purpose LDAP directories in that most of the LDAP operations are write in Grid environments. To get an efficient design of the GIS, it is thus required to analyze the performance of the LDAP system in the context of Grid environments. This paper presents the result of a performance analysis of LDAP systems. The main objective of the evaluation is to see the performance scalability of the LDAP system in the Grid environment where the write operations prevails. Based on these results, we suggest directions of an efficient LDAP-based GIS for a high performance Grid.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.8-16
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• 2022

In this paper, we propose a method of reconstructing the file system to obtain digital forensics information from the APFS file system when meta information that can know the structure of the file system is deleted due to partial damage to the disk. This method is to reconstruct the tree structure of the file system by only retrieving the B-tree node where file/directory information is stored. This method is not a method of constructing nodes based on structural information such as Container Superblock (NXSB) and Volume Checkpoint Superblock (APSB), and B-tree root and leaf node information. The entire disk cluster is traversed to find scattered B-tree leaf nodes and to gather all the information in the file system to build information. It is a method of reconstructing a tree structure of a file/directory based on refined essential data by removing duplicate data. We demonstrate that the proposed method is valid through the results of applying the proposed method by generating numbers of user files and directories.

• Survey Research
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• v.9 no.3
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• pp.55-69
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• 2008

In most telephone surveys in Korea, telephone numbers are selected from the directories. Inevitably, such samples may lack representativeness due to poor coverage rate. To resolve the problem, Kang et al.(2008) implemented RDD(random digit dialing) method for nationwide sampling in Korea. The aim of this study is to compare an RDD sample with a traditional telephone quota sample that were collected independently by two survey institutes commissioned by the KBS-MBC consortium for the 2007 Presidential Election of Korea.

• Journal of the Korean Society for information Management
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• v.23 no.1 s.59
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• pp.99-119
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• 2006

The most widely used information searching method in the current internet environment is the keyword-based one, which has certain limitations in terms of precision and recall. Most major internet portals provide directory-based searching as a means to complement these limitations. However, that they adopt different classification schemes brings significant inconvenience to the users, and it consequently suggests a need to develop mapping gateway to provide cross-portal, or cross-directory information searching. In this context, this study attempts to develop a prototype system of intermediary gateway for integrated search, using the directory services of three major portals, Naver, Yahoo and Empas, and test its performance.