• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.92-96
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• 2000

In this paper, we propose a call admission control(CAC) scheme fer the mixed voice/data DS-CDMA systems and analyze the Er-lang capacity under the proposed CAC scheme. Voice and data traffics require different system resources based oil their Quality of Service(QoS) requirements. In the proposed CAC scheme, some system resources are reserved exclusively for handoff calls to have high priority Over new calls. Additionally the queueing of both new and handoff data traffics that are not sensitive to delay is allowed. Ar a performance measure for the suggested CAC scheme. Erlang capacity is utilized. For the performance analysis, a four-dimensional Markov chain model is developed. Erlang capacity of a practical IS-95B type system depicts, and optimum values of system parameters such as the number of reservation channels and queue lengths are found with respect to Erlang capacity. Finally, it is observed that Erlang capacity is improved more than two times by properly selecting the system parameters with the proposed CAC scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1296-1304
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• 2007

In this paper we researched on the implementation of the B-ISDN protocol embedded IP-PBX System with the computers interconnected by the Internet for the telephone exchange and multimedia communication. For the improvement on the structural problems of the previous PABX we designed the structure of the IP-PBX System, defined message and data structure for call control, designed call control state transition, and implemented call control message flows for user's communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2256-2264
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• 2007

In this paper we researched on the implementation of the B-ISDN protocol embedded IP-PBX System with the computers interconnected by the Internet for the telephone exchange and multimedia communication. For the improvement on the structural problems of the previous PABX we designed the structure of the IP-PBX System, defined message and data structure for call control, designed call control state transition and implemented call control message flows for user's communication.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.336-339
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• 2000

산업의 급속한 발전은 많은 폐자원을 발생시킨다. 특히 연안 지역은 특성상 다양한 산업들에 의해 여러 종류의 폐자원이 배출된다. 본 논문에서는 이러한 연안역의 폐자원 데이터를 관리하고 활용하기 위한 데이터베이스를 구현하였다. 폐자원 및 폐자원 활용 데이터를 표현하기 위한 데이터 모델을 설계하고 구현하였다. 인터넷 환경에서 데이터수집미치검색을 효과적으로 지원할수 있도록 하였다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.1
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• pp.53-56
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• 2010

This paper explains a system that is suitable for detecting software error running on multimedia distance control for transportation safety environment. This system consists of an ED, and ES. ED is an agent that detects an error by hooking techniques for multimedia distance education based on IP-USN gateway software stack environment. ES is an agent that is an error sharing system for multimedia distance control based on IP-USN gateway software stack environment. From the perspective of multimedia collaborative environment, an error application becomes another interactive presentation error is shared with participants engaged in a cooperative work.

• The KIPS Transactions:PartB
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• v.8B no.5
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• pp.501-506
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• 2001

According to the current increase of the usefulness of information by Internet and Communication network, several methods are proposed in which multimedia information may be efficiently managed and serviced. This paper proposes FBOM(Fuzzy-Based Object Manager) using $\alpha$-cut in Object manager for Fuzzy-Based Multimedia Post-Office Box construction. The proposed system utilizes object discrimination, fuzzy filtering, and class generation structure in order to manage object using Fuzzy filtering. To know how well the proposed system are able to work, this paper have tested against the methods with 1000 items of multimedia information, and our system are compared with Random-key method and FBOM method.

• Journal of Korea Multimedia Society
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• v.17 no.5
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• pp.613-622
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• 2014

In spite of the convenience and cost-effectiveness of an electronic document management system the paper-type documents still should be stored for a comparison against the original documents. In this paper, for the efficient management of paper documents, we designed and implemented a document management system using smart devices equipped with NFC(Near Field Communication) technology. To implement the proposed system we designed a database for document management and developed an Android application for smart device using Eclipse 3.0 and Java programming. Whenever we touch the smart phone on the NFC tags which are attached to the paper-type documents and document boxes, it is possible to registering, searching and carrying in and out services for documents and boxes. This study provides smart phone users with systematic, economical and convenient paper-type documents management functions, and thus enhances the business efficiency.

• The Transactions of the Korea Information Processing Society
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• v.6 no.10
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• pp.2618-2629
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• 1999

In this paper, we describe the design and implementation of the FDRA(Fault Detection Recovery based on Agent) running on distributed multimedia environment. DOORAE is a good example for distributed multimedia and multimedia distance education system among students and teachers during lecture. It has primitive service agents. Service functions are implemented with objected oriented concept. FDRA is a multi-agent system. It has been environment, intelligent agents interact with each other, either collaboratively or non-collaboratively, to achieve their goals. The main idea is to detect an error by using polling method. This system detects an error by polling periodically the process with relation to session. And, it is to classify the type of error s automatically by using learning rules. The merit of this system is to use the same method to recovery it as it creates a session. FDRA is a system that is able to detect an error, to classify an error type, and to recover automatically a software error based on distributed multimedia environment.

• Journal of Korea Multimedia Society
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• v.17 no.4
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• pp.433-440
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• 2014

Wireless communication offers the flexibility to the node movement at the spatial dimension more than the wire communication not only in IP architecture but also in Content-Centric Networking. Although it gives such advantage, the intra-domain movement of a node especially the data source node affects the communication to the access point node which in the end affects the acceptance ratio of the client node that requests the data packets from the data source node. In this paper, we use time-division access method to maintain the acceptance ratio of the client node as the effect of the intra-domain data source node movement in Content-Centric Networking. The simulation result shows that the acceptance ratio of the client node can be maintained using the time-division access method as long as the interval access time is less than the coherence time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.3
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• pp.1136-1151
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• 2018

This paper proposes a new hybrid scheme to decrease the high peak to average power ratio (PAPR) of optical orthogonal frequency division multiplexing (OFDM) signals in visible light communication (VLC) systems. The PAPR causes nonlinear signal distortions and high power requirements for the VLC transmitter (light emitting diode, LED). The proposed method is applicable for both direct current-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM). In the proposed scheme, the PTS method is firstly modified to fit both optical OFDM approaches transmission and then combined with signal clipping method for further PAPR reduction and bit error rate (BER) improvement of the VLC system. The performance of hybrid scheme has been evaluated and compared with the original OFDM based VLC system, conventional PTS and clipping methods. The results show that the hybrid scheme outperforms other methods in terms of both the PAPR reduction and BER performance.