• Journal of the Korea Society of Computer and Information
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• v.18 no.7
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• pp.11-21
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• 2013

Recently operating a large scale computing resource like a data center becomes easier because of the virtualization technology that virtualize servers and enable flexible resource provision. The most of public cloud services provides automatic scaling in the form of scale-in or scale-out and these scaling approaches works well to satisfy the service level agreement (SLA) of users. However, a novel scaling approach is required to operate private clouds that has smaller amount of computing resources than vast resources of public clouds. In this paper, we propose a hybrid server scaling architecture and related algorithms using both scale-in and scale-out to achieve higher resource utilization rate for private clouds. We uses dynamic resource allocation and live migration to run our proposed algorithm. Our propose system aims to provide a fine-grain resource scaling by steps. Thus private cloud systems are able to keep stable service and to reduce server management cost by optimizing server utilization. The experiment results show that our proposed approach performs better in resource utilization than the scale-out approach based on the number of users.

• Journal of Internet Computing and Services
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• v.3 no.5
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• pp.31-39
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• 2002

A rapid growth of internet and sudden increase of multimedia data demands for high-speed transfer media and if optimizec usage from the interface system. To achieve this level of network bandwidth, multiple NICs for support of high-speed network bandwidth have been developed and studied. Furthermore, the use of multiple NICs can provide high-speed LAN environment without large network environment modification, supports backward compatibility of current system and reduce overhead. However. if system failure is caused by SPOF(Single Point of Failure) fault of large-capacity multiple NICs, incredible loss will be met because it services large capacity of multimedia data, Therefore, to prevent loss coming from faults, we describe 'Fault tolerance of multiple NICs', which use the fault prevention mechanism. Considering inefficiency of availability and serviceability that is occurred with existing TMR, Primary-Standby approach and Watchdog time mechanism, we propose and design the efficient fault tolerance mechanism, which minimize down time as changing of detection period dynamically. Consequently, the fault tolerance mechanism proposed for reducing overhead time when the fault is occurred, should minimize system downtime overall.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.1
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• pp.48-54
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• 2008

MMORPGs may involve a great number of concurrent players, and those servers usually have to manage hundred, or even thousands of avatars co-existing in the same virtual world. So if failing to send a command or an event message, or sending it too late may cause damages to the avatar evolution(death, injury, loss of resources), and may result in unjustified penalties for the player. Many policies could be defined to realize a ranking evaluation of available servers. Unfortunately, due to the highly dynamic characteristics of server loads and network performances, any optimal allocation would soon become sub-optimal. In order to solve those problems we propose the "time-interval based fairness partitioning method"(TIP). TIP will distribute the avatar to the game server equally with time-interval in order to avoid the problems form the unfairness of game servers load.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.4
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• pp.426-439
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• 1999

본 논문에서는 웹(World Wide Web)에서 사용자가 손쉽고 편리하게 이용할 수 있는 멀티미디어 대중교통 안내시스템 개발 경험을 소개한다. 개발된 시스템은 클라이언트와 서버 시스템, 경로탐색 시스템, 교통정보 저장 시스템, 노선 및 정류장 관리 시스템으로 구성되어 있다. 클라이언트에서 작동되는 사용자 인터페이스는 직관적으로 이해가 쉽고, 사용이 편리하며 인터액티브한 멀티미디어 대중 교통안내 서비스를 제공한다. 서버 시스템은 교통정보 수집 시스템으로부터 입력되는 데이타와, 경로탐색 시스템, 교통정보 저장 시스템과 연동되어 클라이언트의 요구사항을 처리하고 그 결과를 사용자에게 돌려준다. 수정된 A* 알고리즘을 이용하는 경로탐색 시스템은 최적경로를 탐색하며, 교통정보 저장 시스템은 현재 교통상황, 정류장, 노선, 지도 등의 정보를 저장한다. 노선 및 정류장 관리시스템은 시스템 관리자가 노선 또는 정류장 관리를 서버 화면의 지도상에서 효율적으로 수행할 수 있는 도구이다. 본 논문에서 다루는 대중교통 안내시스템은 Java로 구현하였기 때문에 확장과 이식이 용이하며, 시스템 유지보수 비용이 적게 드는 장점을 가지고 있다. 그리고, 웹 브라우저가 동작되는 환경에서는 어디서나 쉽게 접근이 가능하며 향후 구축될 Intelligent Transportation Systems(ITS)의 한 모듈로써 바로 작동될 수 있을 뿐만 아니라, 현재 인터넷상에서 제공되는 다양한 서비스와도 연동이 가능하다.Abstract This paper introduces our experience for developing a public transportation guidance system, which facilitates the World-Wide Web(WWW) to provide users with easier access and use. The proposed system is composed of four subsystems: client/server system, path search system, traffic data storage system, and traffic raw-data management system. The user interface in clients utilizes Java to furnish users with multimedia data accessibility and interactivity. The server processes clients' requests based on the traffic data coming from remote sensing devices and interacts with the path search system and traffic data storage system to provide users with the results. The path search system, which uses a modified A* algorithm, produces optimal solutions based on dynamic traffic data. The traffic data storage system stores the current traffic information together with the geographical information about the b$us_way routes. The traffic raw-data management system is a graphical user interface which enables the system manager to handle the traffic information easily on the map in the terminal screen. The system has considerable benefits such as portability, scalability, and flexibility since it is implemented using Java. Also, it can be extended to an integrated Intelligent Transportation Systems(ITS) which includes a variety of information on the Internet as well as traffic information.n.

• Journal of Intelligence and Information Systems
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• v.13 no.3
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• pp.83-99
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• 2007

Nowadays, the advancement of digital information technology resulting in the increased interest of the management and the use of information has given stimulus to the research on the use and management of information. In this paper, we propose an integrated data mining model that can provide the necessary information and interface to users of scientific information portal service according to their respective classification groups. The integrated model classifies users from log files automatically collected by the web server based on users' behavioral patterns. By classifying the existing users of the web site, which provides information service, and analyzing their patterns, we proposed a web site utilization methodology that provides dynamic interface and user oriented site operating policy. In addition, we believe that our research can provide continuous web site user support, as well as provide information service according to user classification groups.

• Spatial Information Research
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• v.6 no.1
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• pp.47-63
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• 1998

Internet GIS represents the GIS technique that, by integrating Internet and GIS technique, provides geographic information services through Internet environments, Internet GIS suggests that one can search and analyze spatial data through WWW under the dynamic client/ server computing environments, In this paper we introduce the development of a new address management system using GIS technique and a new address information system using Internet GIS, The new address system, which is based on stress name and building number along the street, is developed to complement the current address system which is based on cadastral system, The new address management system is developed for the management of address change due to establishment of roads, construction and destruction of buildings etc using a GIS, The new address information system presents the Internet GIS system which provides people with geographic and address information. By implementing the new address information system it is possible to share GIS data, increase the efficiency of implementation of GIS system, and maximize its usablity.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.2
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• pp.139-144
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• 2007

Due to the increasing use of Internet and spread of ubiquitous environment the security of private information became an important issue. For this reason, many suggestions have been made in order to protect the privacy of users. In the study of authentication system using a smart card which is one of the methods for protecting private information, the main idea is to offer user anonymity. In 2004, Das et al. suggested an authentication system that guarantees anonymity by using a dynamic ID for the first time. However, this scheme couldn't guarantee complete anonymity as the identity of the user became revealed at log-in phase. In 2005, Chien at al. suggested a authentication system that guarantees anonymity, but this was only safe to the outsider(attacker). In this paper, we propose a scheme that enables the mutual authentication between the user and the sewer by using a smart card. For the protection of the user privacy, we suggest an efficient user authentication system that guarantees perfect anonymity to both the outsider and remote server.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.466-474
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• 2007

Asymmetric networks that the downlink bandwidth is larger than the uplink bandwidth may cause the degradation of the TCP performance due to the uplink congestion. In order to solve this problem, this paper designs and implements the Dynamic Segment Size Control mechanism which offers a suitable segment size for current networks. The proposed mechanism does not require any changes in customer premises but suppress the number of ACKs using segment reassembly technique to avoid the uplink congestion. The gateway which adapted the Dynamic Segment Size Control mechanism, detects the uplink congestion condition and dynamically measures the bandwidth asymmetric ratio and the packet loss ratio. The gateway reassembles some of segments received from the server into a large segment and transmits it to the client. This reduces the number of corresponding ACKs. In this mechanism, the SACK option is used when occurs the bit error during the transmission. Based on the simulation in the GEO satellite network environment, we analyzed the performance of the Dynamic Segment Size Control mechanism.

• The KIPS Transactions:PartD
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• v.14D no.3 s.113
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• pp.355-362
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• 2007

With development of mobile communications terminal and expansion of mobile Internet, a large number of users can use mobile web contents at anytime and anywhere and will demand service of greater contents. Due to such demand, many studies are being carried out on transcoding contents so that wired web contents can be used in mobile web. However, transcoding and creation of mobile web contents involve difficulties because specifications available from telecommunications companies and mobile terminals have not been standardized. Especially, in order for serving dynamic object of wired web page contents to dynamically change according to time or user, it is required not only to program scripts to suit each terminal, but also to transcode the resources used in advance. for solution to this problem, this study uses the hierarchy structure of DOM (document object model) to display structural characteristics of wired web page. In other words, this study proposes the following technique. Wired web pages are analyzed and the results are established as data structure. Then, dynamic object is extracted and the domain is indexed so that, when serving mobile web page, information can be extracted at the indexed position to create mobile web contents for service on real-time basis. Also, this study aims at developing an editing device to edit mobile web contents and mobile web service server to service the edited contents by applying the above technique.

• Journal of Intelligence and Information Systems
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• v.15 no.1
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• pp.31-50
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• 2009

As the collected information which is static or dynamic is infinite in ubiquitous computing environments, information overload and invasion of privacy have been pressing issues in the recommendation service. In this study, we propose a recommendation service procedure through P2P, The P2P helps customer to obtain effective and secure product information because of communication among customers who have the similar preference about the products without connection to server. To evaluate the performance of the proposed recommendation service, we utilized real transaction and product data of the Korean mobile company which service character images. We developed a prototype recommender system and demonstrated that the proposed recommendation service makes an effect on recommending product in the ubiquitous environments. We expect that the information overload and invasion of privacy will be solved by the proposed recommendation procedure in ubiquitous environment.