• Journal of KIISE:Computer Systems and Theory
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• v.32 no.1
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• pp.21-28
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• 2005

Web servers or web application servers, in general, adopt multi-thread model for efficient handling of many user requests. However, the multi -thread model always does not show the better performance than multi -process model. Sometimes, in a certain specific case, it can show worse performance than multi -process model. In this paper, to trace the cause of the decreased performance of multi -thread model, we experiment and analyze the performance of the multi-thread model by using two approaches. At first, we compare the performance of the multi-process model and multi-thread model for various application environments. Second, we observe the effects of variations of web server's dynamic directives, which are used to increase the flexibility of the web server for various system environments. For the experiments, we integrated a web client simulator, which was written by us, with the Apache 2.0 web server. This paper shows and analyze the results of the experiments.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.551-557
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• 2015

Synchronization methods for shared data need to be selected properly based on characteristics of data and applications. In this paper we suggest a new semantic synchronization method, semanticAppr, for non_transactional data in disconnected mode. Our approach reduces loss of works in cooperative environments by weakening constraint of serializability. In addition it reduces data transfer by sending operation log instead document itself.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.5
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• pp.607-617
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• 2002

IETF has proposed CNRP that is a protocol exchanging CNRP objects between server and client for resolving a common name to URIs of the desired Internet resouces. CNRP enables users to access various services via the integrated interface, to easily get the desired resources, and to reuse the results not as the data but as the information. Whereby these advantages, CNRP will be generally used for the integration of the various Internet services or the applications where the resolution of common name is needed. But, CNRP specification doesn't describes the practical implementation method for server and client. Though a few prototype systems are developed in some researches using CNRP, they are not enough to be generally used for the various Internet applications because they doesn't include all objects specified in CNRP specification or they construct systems with one server. So, this Paper proposes the practical implementation method for CNRP server/client through analyzing and solving the problems occurred when implementing them, and implements all objects specified in CNRP specification. This paper also verifies the feasibility of the proposed method by developing the prototype system of the company name resolution service using the CNRP server/client implemented in this study. The CNRP server/client implemented in this paper are used to develop various CNRP application systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.101-108
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• 2004

SIP(Session Initiation Protocol) is a suitable protocol for supporting Internet telephony services and currently market requirements fur developing supplementary telephony services such as unconditional call forwarding, call forwarding on busy or no answer, call filtering services have recently grown. CPL(Call Processing Language) is a standard technology that can be used to describe and control internet telephony services. In this paper, we describe the CPL system for supplementary Internet telephony services using SIP as an application level call signaling protocol. Those supplementary services are composed of CPL client which is a SIP UA, SIP Proxy server, Registrar and CPL server In this paper, we describe the design and implementation of the CPL server system in detail which is developed in Linux 7.2 using C and C++ programming languages.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.975-982
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• 2004

In current P2P concept, pure P2P and Hybrid P2P structures are used commonly. Gnutella and Ktella are forms of pure P2P. and forms of Hybrid P2P are innumerable. File searching models exist in these models. These models provide group management for file sharing, searching and indexing. The general file sharing model is good at maintaining connectivity. However, it is defective in group management. Therefore, this study approaches hierarchical structure in file sharing models through routing technique and backup system. This system was designed so that the user was able to maintain group efficiency and connection reliability in large-scale network.

• The KIPS Transactions:PartD
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• v.12D no.6 s.102
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• pp.849-856
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• 2005

As XML is more proliferate as a data type between internet programs, automatic generation methods of user input form interfaces get more attention. Recently, generating user interfaces for web application or web service clients become very popular. In this paper, we study the method of automatic generation for XForms-based user interface codes based on XML structure definitions in DTD. With the repetitive edit action model, we present a formal generation method of Input form codes and the overall user interface pages. For the generated code is using XForms as a target language, the result is clear and efficient with the MVC structure. Also, we have developed XFormsGen system which implements the proposed method over the Orbeon presentation server.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.59-64
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• 2008

In this paper, stability and transparency analysis for client/server haptic-based networked virtual environment (NVE) is introduced. From this analysis the appropriate communication structure for the more stable and transparent haptic interactions can be derived. Also, it is possible to expect and compensate the quality deterioration of haptic interactions according to certain network conditions In order to verify the usefulness of the analysis, simple haptic-based NVE application is implemented. For the stability verification, the vibration or strange movement of haptic interface and virtual object are measured under various network states. In addition, the usefulness of the proposed transparency analysis and network delay compensation scheme is verified by comparing distorted and compensated force feedbacks with real force feedback.

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.413-420
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• 2005

In this paper, we describe a design and implementation of Web Services that convert WML(Wireless Markup Language) Page into .NET Mobile Web Page. The Web Services has an advantage that is available everybody without restriction oi platform and programming language. In this paper, we implement the Web Services Provider providing of converting system and the Web Services Consumer using this system. The Clients can get results of .NET Mobile Web Page without difficulty through Web Server because of implementation of Web Services Consumer using Web Services. Also the clients can develop new application using Web Services without respect of its implement process.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.77-82
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• 2006

최근 컴퓨팅 환경은 클라이언트-서버(client-server) 환경에서 웹(World Wide Web)을 기반으로 한 분산 컴퓨팅(distributed computint) 환경으로 변화하고 있다. 그에 따라 XML 문서의 사용과 XML 문서의 양이 급속하게 증가하였다. 언제 어디서나 쉽게 필요한 XML 문서에 접근해야하며, 이러한 응용을 위해 짧은 시간 내에 그 정보를 전달할 수 있어야 한다. 이에 따라 분산 환경에서의 XML 문서의 처리가 요구된다. XML 데이터를 분산 데이터베이스의 특성을 이용하여 저장, 관리, 질의하는 분산 XML 데이터베이스 시스템(Distributed XML Database System)의 사용의 필요성이 증가하고 있다. 이에 따라, 사이트의 자치성, 질의 최적화, 데이터의 투명성 등에 큰 영향을 미치는 분산 XML 데이터베이스 시스템에서의 카탈로그 관리 기법의 연구의 필요성이 증가하게 된다. 본 논문에서는 중앙 집중식 카탈로그와 완전 중복식 카탈로그, 분할식 카탈로그를 분산 XML 데이터베이스 시스템에서 CPU 비용, I/O 비용, 동시성 제어, 이단계 완료 프로토콜, 큐잉 지연 등을 모두 고려한 모델을 설계하였고, 이를 시뮬레이터로 구현하여 각 카탈로그 관리 기법들의 성능을 합리적인 환경 설정을 통해 시뮬레이션함으로써 카탈로그 관리 기법들의 성능을 평가하였다.

• Journal of the Korea Convergence Society
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• v.2 no.4
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• pp.9-14
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• 2011

Phishing is an attack to theft an user's identity by masquerading the user or the device. The number of phishing victims are sharply increased due to wide spread use of smart phones and messenger programs. Smart phones can operate various wi-fi based apps besides typical voice call and SMS functions. Generally, the messenger program such as Kakao Talk or Nate On is consisted of client and server functions. Thus, the authentication between the client and the server is essential to communicate securely. In this paper, we propose the messenger authentication protocol safe against smart phone phishing. To protect communications among clients, the proposed method provides message encryption and authentication functions.