• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.270-273
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• 2007

The overlay multicast that has been recently presented as an alternative for the IP multicast has been getting much persuasion by the advancement of the network techniques to enforce routing in application-level. But, The overlay multicast is a problem of delay and the load of the traffic control. In this paper, we suggested to an effective transmission routing tree between users based on overlay multicast of Internet broadcasting Service. And we evaluated an optimal value of transmission delay about Internet broadcasting using this suggest model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7B
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• pp.431-437
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• 2007

Web proxy caching provides an effective way to reduce access latency and bandwidth requirement. In particular, prefix caching is considered as an alternative for improving video delivery over wide area networks because video objects are usually too large to be cached in their entirety. Nevertheless, many studies have pointed that the user-perceived latency is often not dominated by object transmission time, but rather by setup process such as TCP connection time that precedes it. We propose pre-connecting techniques and show that the techniques can be used efficiently in TCP splicing. Our analysis shows the pre-connection significantly reduces start-up latency and TCP connection time in simple analytical model. The deployment of the proposed pre-connection does not require protocol modification or the cooperation of other entities.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.511-514
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• 2002

In may automated systems such as manufacturing systems and process plants, an industrial network or fieldbus is a very important component for the exchange of various and sometimes crucial information. Some of the information has a tendency to rapidly lose its value as time elapses after its creation. Such information or data is called real-time data that includes sensor values and control commands. In order to deliver these data in time, the fieldbus network should be tailored to have short delay with respect to the individual time limit of various data. Fine-tuning the network for a given traffic requires the knowledge on the relationship between the protocol parameters such as timer values and the performance measure such as network delay. This paper presents a mathematical performance model to calculate communication delays of the Profibus FMS network when the timer value TTR and the traffic characteristics are given. The results of this model is compared to those from experiments to assess the model's validity.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.2
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• pp.151-156
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• 2008

This paper presents the stability analysis and design for a sampled-data fuzzy control system with neutral type of time delay, which is formed by a nonlinear plant and a sampled-data fuzzy controller connected in a closed loop. The sampling activity and neutral type of time delay will complicate the system dynamics and make the stability analysis much more difficult than that for a pure continuous-time fuzzy control system. Based on the fuzzy-model-based control approach, LMI(linear matrix inequality)-based stability conditions are derived to guarantee the nonlinear networked system stability. An application example will be given to show the merits and design a procedure of the proposed approach.

• IE interfaces
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• v.9 no.3
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• pp.180-193
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• 1996

본 논문에서는 시뮬레이션 모델을 통해 호유형뿐만 아니라 개인통신서비스에서 필수적인 핸드오버 및 위치등록 등의 모든 트래픽 유형을 고래했을 때 개인통신교환기(PCX : Personal Commuincations Exchange)에서의 지연시간을 분석하며, 지연시간에 대한 결과와 프로세서의 이용율로부터 개인통신교환기의 호처리 및 이동성처리용량을 분석하고 그에 따른 가입자의 수용능력을 추정한다. IPC(Inter-Processor Communications) 메시지의 송수신시간 및 메시지의 처리시간등 교환기 제어계의 성능분석에 필요한 입력 파라미터 값은 기존 ISDN(Integrated Services Digital Network) 및 CMS-MX(CDMA Mobile System-Mobile Exchange) 교환기의 측정자료를 이용하였다. 시뮬레이션 분석결과 PCX 교환기의 호처리 성능은 주로 번호번역 기능을 담당하는 프로세서인 NTP(Number Translation Processor)의 용량에 의해 결정되며, 가입자 밀도가 1,500명$/km^2$인 경우 호처리용량은 약 42만 BHC(Busy Hour Call Completion)로 추정되었고, 이에 상응하는 핸드오버 및 위치등록 처리용량은 각각 시간당 약 2만 6천히 및 40만 6천회로 나타났다. 이것은 가입자당 호처리 부하가 1.6BHC일 경우, 약 15만 7천 가입자를 수용할 수 있는 용량에 해당한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1A
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• pp.46-54
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• 2005

This paper presents an effcient mobile multicast method using the user pattern. We exploit the repetitive movement pattern of mobile node to reduce the total number of experience of graft and join procedure. We defined the locality scope by a movement pattern. While the network is included in the locality scope, the network should maintain a multicast tree even when the mobile node moves to the other network. In this way, the mobile host can receive a multicast service without a delay when it moves to the network in the locality scope later. We compare our scheme with existing schemes under the total signaling cost and the service delay time by using a discrete analytical model for cost analysis. Analytical results demonstrated that the total signaling cost and service delay time was significantly reduced through our proposed scheme.

• Fire Science and Engineering
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• v.18 no.2
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• pp.27-33
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• 2004

An accurate knowledge of the AIT(Autoignition temperatures) of chemicals is important in developing appropriate prevention and control measures in industrial fire protection. The AITs describe the minimum temperature to which a substance must be heated, without the application of a flame or spark, which will cause that substance to ignite. The measurement AITs are dependent upon many factors. namely initial temperature. pressure, volume, fuel/air stoichiometry. catalyst material, concentration of vapor, ignition delay time. This study measured the AITs of acids from ignition delay time by using ASTM E659-78 apparatus which was produced in the year 1994. The experiment AITs were a good agreement with the calculated AITs by the proposed equations with a few A.A.P.E.(average absolute percent error) and A.A.D.(average absolute deviation).

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.335-340
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• 2008

In this paper, a decentralized fuzzy output feedback controller for nonlinear interconnected systems with time delay is proposed. The nonlinear interconnected system is represented to fuzzy system using Takagi-Sugeno (T-S) fuzzy model. The decentralized output feedback controller is designed(or stability of subsystems of the fuzzy interconnected system. The stable condition of the closed-loop subsystem is represented to the linear matrix inequality (LMI) form and control gain is obtained by LMI. An example is given to show the verification discussed throughout the paper.

• Journal of Korea Multimedia Society
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• v.7 no.2
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• pp.194-203
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• 2004

In this paper we propose a Mobile Petri-net Model (MPM) as a new specification model including the QoS parameter that minimizes the transmission delay time. In MPM, we propose a playing time algorithm for supporting the seamless presentation and the smooth playing. The proposed model has a higher guarantee of QoS such as playing time than the previous work.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.149-155
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• 1992

본 사례연구는 자동차용 스프링 제조업체의 생산합리화를 위하여 조립라인에서의 효율적인 조립을 위한 전 생산공정의 평준화 생산 방안에 관한 것이다. 조립라인에서 조립작업의 지연 및 불균형은 그 근본 원인이 애로공정인 열간작업 및 열처리공정에서의 모델별.낱장로트별로 작업공정 구성과 작업처리속도에서 불균형을 이루기 때문이다. 결국 열간작업과 열처리공정이 전공정에서의 생산량과 공정간재고를 통제한다. 위와 같은 문제를 해결하기 위해서는 모기업의 수요를 기점으로하여 필요한 제품을 필요한 양만큼 필요할 때에 공급할 수 있는 마케트인(market in)방식의 인출(pull)시스템을 구축하여야 한다. 따라서 전 생산공정을 크게 압연공정, 열간작업공정, 열처리.조립공정으로 나누어서 용량(capacity)측면에서가 아니라 흐름(flow)측면에서 주문품목에 대하여 모델별.낱장별로 그룹화하고 모델별 조립작업순서와 열처리공정의 투입순서 및 투입량, 열간작업에 대한 작업순서를 결정하여 전체의 생산공정이 평준화 될 수 있는 생산통제방안을 제시한다. 아울러 이 생산통제 방안들의 타당성을 평가하기 위하여 컴퓨터 시뮬레이션을 통한 분석도 행하였다.