• Journal of KIISE:Computer Systems and Theory
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• v.33 no.10
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• pp.734-745
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• 2006

This paper presents a PC cluster-based distributed VOD server that minimizes the load of an interconnection network by adopting the VIA communication protocol and the interval cache algorithm. Video data is distributed to the disks of the distributed VOD server and each server node receives the data through the interconnection network and sends it to clients. The load of the interconnection network increases because of the large amount of video data transferred. This paper developed a distributed VOD file system, which is based on VIA, to minimize cost using interconnection network when accessing remote disks. VIA is a user-level communication protocol removing the overhead of TCP/IP. This papers also improved the performance of the interconnection network by expanding the maximum transfer size of VIA. In addition, the interval cache reduces traffic on the interconnection network by caching, in main memory, the video data transferred from disks of remote server nodes. Experiments using the distributed VOD server of this paper showed a maximum performance improvement of 21.3% compared with a distributed VOD server without VIA and the interval cache, when used with a four-node PC cluster.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.37-58
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• 2011

In general, testing DB applications is much more difficult than testing other types of software. The fact that the DB states as much as the input data influence and determine the procedures and results of program testing is one of the decisive reasons for the difficulties. In order to create and maintain proper DB states for testing, it not only takes a lot of time and efforts, but also requires extensive IT expertise and business knowledge. Despite the difficulties, there are not enough research and tools for the needed help. This article reports the result of research on automatic creation and maintenance of DB states for testing DB applications. As its core, this investigation develops an automation tool which collects relevant information from a variety of sources such as log, schema, tables and messages, combines collected information intelligently, and creates pre- and post-Images of database tables proper for application tests. The proposed procedures and tool are expected to be greatly helpful for overcoming inefficiencies and difficulties in not just unit and integration tests but including regression tests. Practically, the tool and procedures proposed in this research allows developers to improve their productivity by reducing time and effort required for creating and maintaining appropriate DB sates, and enhances the quality of DB applications since they are conducive to a wider variety of test cases and support regression tests. Academically, this research deepens our understanding and introduces new approach to testing enterprise systems by analyzing patterns of SQL usages and defining a grammar to express and process the patterns.

• Journal of Korean Library and Information Science Society
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• v.44 no.2
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• pp.217-239
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• 2013

This research was conducted to analyze the actual condition of subject heading related to Korean border shown in the subject headings of 7 countries: United States, France, Germany, Spain, Russia, China, and Japan. The results are as follows. To begin with, Korean border-related records in most other national libraries are in extremely poor conditions except for some countries like United States. Amnokgang and Dumangang-related records did not search at all in the France. Yellow Sea, Dumangang, and Baekdusan-related records did not search at all in the Spain. Second, even Dokdo we have effective control, the geographical name 'Korea' is not marked with catalog records except the United States and France. The Germany is displayed with the geographical name of 'Korea' and 'Japan'. Third, the East Sea(Donghae) already is marked with 'Sea of Japan' in most of the national library catalogs, and Yellow Sea(Huanghai) is marked with 'Yellow Sea'. Fourth, Amnokgang and Dumangang is marked with Chinese pronunciation in most in most of the national library. Fifth, Baekdusan is marked with Korean pronunciation in most countries. However the United States showed in 'Baekdu Mountain' and 'Changbai Mountain' discrimination. In the case of the Germany, 'Changbai Mountain' are marked with variant access point of 'Baekdusan'.

• Journal of Environmental Policy
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• v.7 no.1
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• pp.81-100
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• 2008

This paper reviewed the main characteristics of Web 2.0 and discussed the possible applications related to National Geographic Information Systems. In general, Web 2.0 refers to a next generation World Wide Web environment that let people participate and share information and data. The recent examples using Web 2.0 with geo-spatial information are convincing us apply Web 2.0 into National Geographic Information Systems. In order to imply Web 2.0 into National Geographic Information Systems, we should consider not only technological advancements related to providing the services but also shifting the relationship between information provider(government agencies) and end-users. In other words, new platform should be provided to users so that users can easily create, share, and mash-up data, which was previously managed and owned only by government agencies. Successful integration Web 2.0 platform into National Geographic Information Systems require some important points such that; 1) the consideration for the data should be changed from closed and agency owned data to opened and shared data. 2) data standards should be established to integrate all data from different sources. 3) real change need to be happened rather than different naming on the same system.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.25 no.3
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• pp.165-189
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• 2014

This study examined the current practices of Research Data Management (RDM) services recently built and implemented at research university libraries in the U.S. by analyzing the components of the services and the contents presented in their web sites. The study then analyzed the content of web pages describing the services provided by 31 Research Universities/Very High research activity determined based on the Carnegie Classification. The analysis was based on 9 components of the services suggested by previous studies, including (1) DMP support; (2) File organization; (3) Data description; (4) Data storage; (5) Data sharing and access; (6) Data preservation; (7) Data citation; (8) Data management training; (9) Intellectual property of data. As a result, the vast majority of the universities offered the service of DMP support. More than half of the universities provided the services for describing and preserving data, as well as data management training. Specifically, RDM services focused on offering the guidance to disciplinary metadata and repositories of relevance, or training via individual consulting services. More research and discussion is necessary to better understand an intra- or inter-institutional collaboration for implementing the services and knowledge and competency of librarians in charge of the services.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.1-7
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• 2015

Recently, a coaching helps individual to lead and maximize performance. Generally there is a face to face coaching at the current spot of education, and the e-coaching is on the rise. And the face-to-face coaching means that coach and the coachee come face to face directly. And, the effective coaching method is required to supply the weakness and to maximize the strength of the e-coaching using the Internet. Accordingly, we are studying a hybrid coaching to overcome the difficulty and the limit of face-to-face coaching and online coaching. In this paper, we design and implement the career coaching system to provide the face-to-face coaching and the e-coaching for coachee based on the Web service on the Internet. We provide the hybrid coaching using Web service based on the Restful and connect with the database based on the Web to save and manage the profiles and the coaching history of the coach and the coachee. Proposed hybrid coaching system for coachee career improves remote accessibility between the coach and the coachee. This system provides the interaction without the limit of the time and the space, and overcomes the limit of the traditional face-to-face coaching on the online environment.

• Journal of Internet Computing and Services
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• v.21 no.2
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• pp.39-48
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• 2020

Data mining techniques have been suggested to find efficiently meaningful and useful information. Especially, in the big data environments, as data becomes accumulated in several applications, related pattern mining methods have been proposed. Recently, instead of analyzing not only static data stored already in files or databases, mining dynamic data incrementally generated in a real time is considered as more interesting research areas because these dynamic data can be only one time read. With this reason, researches of how these dynamic data are mined efficiently have been studied. Moreover, approaches of mining representative patterns such as maximal pattern mining have been proposed since a huge number of result patterns as mining results are generated. As another issue, to discover more meaningful patterns in real world, weights of items in weighted pattern mining have been used, In real situation, profits, costs, and so on of items can be utilized as weights. In this paper, we analyzed weighted maximal pattern mining approaches for data generated incrementally. Maximal representative pattern mining techniques, and incremental pattern mining methods. And then, the application scenarios for analyzing the required commodity patterns in infants are presented by applying weighting representative pattern mining. Furthermore, the performance of state-of-the-art algorithms have been evaluated. As a result, we show that incremental weighted maximal pattern mining technique has better performance than incremental weighted pattern mining and weighted maximal pattern mining.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.8
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• pp.1735-1742
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• 2011

Now a days, as a mass-storage USB becomes comfortable to carry, function of USB is being developed fast. However, there is a problem that the personal information which is stored in USB could be exposed being used with negative purpose without other certification process. This paper suggests OTP(One-Time Password)-based certification protocol of USB to securely protect personal information stored in USB without additional certification information. The proposed OTP based certification protocol of USB not only demands low calculations but also prevents physical approach of USB of other network and does not allow unnecessary service access of user because it conducts simple action and uses one-way hash function. Therefore, communication overhead and service delay is improved. In the experiment, the proposed protocol compares and evaluates throughput of certification server according to the numbers of USB and delay time of packet certification with a device(USB driver) which simply save device and a device(USB Token) which can calculate by oneself. As a result, it is improved as the number of 12.5% in the certification delay time on average and is improved as the number of 10.8% in the throughput of certification server according to the numbers of USB.

• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.20-28
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• 2005

TCP(Transmission Control Protocol) is one of the most important Internet protocols, which is widely used in wireless networks as well as wired networks. However, when TCP is deployed for wireless networks, it takes severe performance degradation because TCP was designed for wired network. To overcome this drawback, a number of TCP variants have been proposed in the literature. However, most previous schemes did not consider TCP enhancement over heterogeneous networks. In heterogeneous networks, an mobile node (MN) may move from one access network to another(i.e., vertical handover). In the case of vertical handover, an MN experiences a TCP performance degradation caused by the packet loss and the sudden change of link characteristics between two different access networks. In this work, we investigate the TCP performance degradation occurred in vortical handover across heterogeneous networks. First, we have conducted the measurement study over GPRS-WLAN testbed. In the measurement study. we observed the TCP performance degradation in the case of handover from WLAN to GPRS. In order to study more different TCP behaviors during vertical handover, we performed comprehensive simulations using a network simulator 2(ns-2). Based on measurement and simulation results, we investigated how to improve TCP performance in vertical handover and we concluded that the existing mechanisms cannot be perfect solutions and new mechanisms are strongly required.

• The KIPS Transactions:PartA
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• v.15A no.1
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• pp.45-52
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• 2008

In this paper we define a vulnerable code to symbolic link exploit and propose a technique to detect this using program analysis. The existing methods to solve symbolic link exploit is for protecting it, on accessing a temporary file they should perform an investigation whether the file is attacked by symbolic link exploit. If programmers miss the investigation, the program may be revealed to symbolic link exploit. Because our technique detects all the vulnerable codes to symbolic link exploit, it helps programmers keep the program safety. Our technique add two type qualifiers to the existing type system to analyze vulnerable codes to symbolic link exploit, it detects the vulnerable codes using type checking including the added type qualifiers. Our technique detects all the vulnerable codes to symbolic link exploit automatically, it has the advantage of saving costs of modifying and of overviewing all codes because programmers apply the methods protecting symbolic link exploit to only the detected codes as vulnerable. We experiment our analyzer with widely used programs. In our experiments only a portion of all the function fopen() is analyzed as the vulnerabilities to symbolic link exploit. It shows that our technique is useful to diminish modifying codes.