• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8C
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• pp.758-770
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• 2002

In this paper, we propose a novel resource allocation scheme which can maximize capacity for QoS guarantee of Assured Service in Differentiated Services. Performance of the proposed resource allocation scheme is analyzed with each buffer management scheme such as RIO and Adaptive RIO. To prevent an early random drop of the admitted In-profile packet, Adaptive RIO scheme updates parameters of RIO scheme every time interval according to the estimated numbers of maximum packet arrivals of In-profile traffic and Out-of-profile traffic during the next time interval. The numbers of maximum packet arrivals during the next time interval are estimated based on the buffer size determined by the network topology and the ratio of bandwidth allocated to each subclass. We can find from simulation results that proposed resource allocation scheme with Adaptive RIO can guarantee QoS and can maximize capacity for Assured Service.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.3
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• pp.61-67
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• 2008

Proxy MIPv6 (PMIPv6) is that network-based mobility management protocol that network supports mobile node's mobility on behalf of the MN. In PMIPv6, when two MNs located within the same PMIPv6 domain want to communicate each other, sub-optimal path is established between the two MN. Route optimization method for PMIPv6 is proposed to resolve the problem. However, the method still suffer from the performance degradation due to out-of-sequence packet problem. In this paper, we propose the route optimization mechanism in PMIPv6 based on Flush message to resolve the out-of-sequence packet problem. The proposed mechanism is evaluated by performing simulations, and the simulation results show that the proposed one gives better performance.

• The Transactions of the Korea Information Processing Society
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• v.5 no.5
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• pp.1320-1332
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• 1998

We propose Multiph which is a virtual topology for a reliable group communication platform on dynamic high speed network. We also define group communication primitives for transmission of messages and group management. Multiph consists of a set of nodes which are process groups and a set of edges which are the connection between nodes providing the route of messages. Processes can send and receive messages overlapped in a several multicast groups. Overlapped process organizes non-overlapped logical group, which called meta-group. Multiph guarantees ordering of messages that received at the destination group. It has no extra node that decreases system performance. Although the group has dynamic group change to leave and add process, it does not reconstruct the existing platform structure.

• Smart Media Journal
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• v.5 no.4
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• pp.18-25
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• 2016

Virtualized hardware resources provides efficiency in use and easy of management. Based on the benefits, virtualization techniques are used to build large server clusters and cloud systems. The performance of a virtualized system is significantly affected by the virtual machine scheduler. However, the existing virtual machine scheduler have a problem in that the I/O response is reduced in accordance with the scheduling delay becomes longer. In this paper, we introduce the Loan/Redemption mechanism of a virtual machine scheduler in order to improve the responsiveness to I/O events. The proposed scheme gives additional credits for to virtual machines and classifies the task characteristics of each virtual machine by analyzing the credit consumption pattern. When an I/O event arrives, the scheduling priority of a virtual machine is temporally increased based on the analysis. The evaluation based on the implementation shows that the proposed scheme improves the I/O response 60% and bandwidth of virtual machines 62% compared to those of the existing virtual machine scheduler.

• Proceedings of the KOR-KST Conference
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• 1998.10b
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• pp.297-297
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• 1998

고속도로의 교통혼잡을 관리하기 위해서는 근본적으로 혼잡지점 상류부의 진입교통량을 제어해야 한다. 이를 위한 효과적인 램프미터링 운영전략이나 고속도로 교통정보제공방안을 수립하기 위해서는 혼잡영향권(대기행렬길이)에 관한 신뢰성 있는 데이터가 반드시 필요하다. 고속도로의 대기행렬길이를 산정하기 위해 일반적으로 충격파이론과 Queueing이론을 제시하고 있다. 그러나, 기존의 충격파 이론을 포물선형의 교통량-밀도관계식을 근거로 하고 있어 충격파간에 발생하는 부수적인 충격파를 해석하는 과정이 수학적으로 불가능하여 실질적인 목적으로 사용할 수 없음은 이미 잘 알고 있는 사실이다. 최근에 이러한 한계를 극복할 수 있는 새로운 방법으로 교통량 밀도간의 관계식을 삼각형으로 가정하고 교통량 대신에 누적교통량을 사용하는 Simplified Theory of Kinematic Waves In Highway Traffic이 개발(Newell, 1993)되었지만, 이 방법을 적용하기 위해서는 기본적으로 대상 고속도로 구간의 교통량-밀도관계식을 규명해야 하는 어려움이 있다.(사실 실시간으로 밀도데이터를 수집하기란 불가능하다.) Queueing이론에서 제시하는 대기행렬은 모두 대기차량이 병목지점에 수직으로 정렬하여 도로를 점유하지 않는 Point Queue(혹은 Vertical stack Queue)로서 실제로 도로상에 정렬된 대기행렬(Real Physical Queue)과는 전혀 다르다. 이미 입증된 바 있어, Queueing이론을 이용함은 타당성이 없다. 이러한 사실에 근거하여 본 연구는 고속도로 대기행렬길이를 산정할 수 있는 모형개발을 위한 기초연구로서 혼잡상태의 연속류 특성을 분석하는데 목적이 있다. 이를 위해, 본 연구에서는 서울시 도시고속도로에서 수집한 실제 데이터를 이용하여 진입램프지점의 혼잡상태에서 대기행렬의 증가 또는 감소하는 과정을 분석하였다. 주요 분석결과는 다음과 같다. 1. 혼잡초기의 대기행렬은 다른 혼잡시기에 비해 상대적으로 급속한 속도로 증가함. 2. 혼잡초기의 대기행렬의 밀도는 다른 혼잡시기에 비해 비교적 낮음. 3. 위의 두 결과는 서로 관계가 있으며, 혼잡시 운전자의 행태(차두간격)과 혼잡기간중에도 변화함을 의미함. 4. 교통변수 중에서 대기행렬길이를 산정하는데 적합한 교통변수를 교통량과 밀도로 판단됨. 5. Queueing이론에서 제시하는 대리행렬길이 산정방법인 대기차량대수$\times$평균차두간격은 대기행렬내 밀도가 일정하지 않아 부적합함을 재확인함. 6. 혼잡초기를 제외한 혼잡기간 중 대기행렬길이는 밀도데이터 없이도 혼잡 상류부의 도착교통량과 병목지점 본선통과교통량만을 이용하여 추정이 가능함. 7. 이상에 연구한 결과를 토대로, 고속도로 대기행렬길이를 산정할 수 있는 기초적인 도형을 제시함.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1037-1053
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• 1991

Flooding is known to be an effective routing mechanism not only in circuit switched networks but also packet switched networks since it minimizes the time required for up calls and does not have to maintain routing tables or distance tables by periodically intercommunicating among all the network nodes. However, one main drawback of it is the overhead on the control message signaling channels, In the paper, we propose an overlaying scheme on the existing mechanism that retains the desired properties of flooding, yet provides congestion control to the network. This is done by utilizing the wasted search messages to inform the network of the conditions of each path from one node to another. The overhead is to maintain a path table in each node. However, this overhead is not so critical. Also, this scheme can take advantages further by limiting the extent of message propagation through the network and by incorporating trunk reservation schemes additionally.

• International Commerce and Information Review
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• v.1 no.1
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• pp.131-156
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• 1999

최근의 통상환경중 "Logistics" 혁명을 통한 컨테이너 운송의 신속화, 인터넷혁명을 통한 전자상거래 활성화는 EDI, EC등을 통해 "Paperless trade"가 실현을 앞당기고 있다. 본 논고는 이러한 물류혁명과 인터넷 정보기술의 발달로 대두되는 문제중 기존의 종이서류로서의 운송서류를 전자식 운송서류로 대체하는데 따른 문제점과 이의 활성화 방안에 대해서 살펴보고자 한다. 인터넷 전자거래가 활성화되어지면 기존의 종이서류들은 전자메시지로 대체될 것으로 여겨진다. 이에 따라 전자계약서, 전자송장, 전자보험증권, 전자선하증권 등이 출현할 것이지만 이중 무엇보다도 전자식 운송서류중 유통성 운송서류의 전자화는 그간 전자화의 핵심부문으로 여겨서 상당한 중요성을 두어왔다. 현재 이용되는 유통성 운송서류는 그간 선하증권의 지연도착문제와 이에 따른 추가 경비의 소요, 또한 선하증권 발급에 따른 부대경비의 과다소비, 종이서류로서의 선하증권의 위조에 따른 사기문제 등에 제기되어 졌고 이에 따라 선취화물보상장 등의 현실적 대안이 제시되었지만 이 또한 여러 문제점을 야기시켜왔다. 전자식 운송서류는 이러한 문제점을 다소 해소할 수 있는 방안으로 알려져 왔다. 전자거래가 활성활 될 미래에는 운송서류의 전자화는 필연적으로 대두되게 될 것이고, 이러한 전자화에 있어 해상운송장의 사용은 바람직한 모델로 여겨지고 있다. 그렇지만 전매가 잦은 산업에 있어 해상운송장은 자체의 유통성의 미비로 인해 그 사용에 문제점이 있고, 실제 상관행에서 많은 이점을 가진 선하증권의 발행 욕구를 충족시켜 줄 수 있어야 할 것이다. 본 논고에서는 전자식 운송서류의 활성화 방안으로 첫째, 전자식 운송서류에 관한 법률정비가 필요할 것으로 여겨지며 둘째, 유통성 전자식 운송서류에 있어 관리기관의 안정성이 확보되어야 할 것으로 여겨지며 셋째, UCP에서 전자식 운송서류에 관한 조항이 삽입되어져야 할것으로 여겨지며 넷째, 여러 측면에서 우위성을 지닌 전자무역거래의 활성화는 점차적으로 운송서류의 전자화를 활성화시키는데 반드시 필요한 명제로 등장할 것으로 여겨진다.

• Journal of the Korea Society of Computer and Information
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• v.18 no.10
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• pp.47-54
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• 2013

In this paper, the structural design of optical Internet is analyzed and by using UNI (User Network Interface) signaling protocol an optical transmission experiment was performed. The hierarchical structure of the basic optical Internet consists of the backbone network, the service network and the access network. The necessary functions for each layer were described as follows: Control structure of the optical transport layer, network operation and management structure, internetworking technology of sub networks, routing and signaling technology. By using UNI signaling protocol from OIF (Optical Internetworking Forum), the optical transmission in the proposed structure of the optical Internet network was experimented. By the traffic generation of LSP (Label Switched Path) data packets along the route-configuration was delivered to UNI. Finally, by showing the value of TCP (Transmission Control Protocol) packets the optical transmission was completely and successfully demonstrated.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.112-123
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• 2017

The accurate forecasting of the public transportation's transit and arrival time has become increasingly important as more people use buses and subways instead of personal vehicles under the government's public transportation promotion policy. Using bus management system (BMS) data, which provide information on the real-time bus location, operation interval, and operation history, it is now possible to analyze the bus schedule reliability. However, the punctuality should always be considered together with the operation safety. Therefore, this study suggests a new methodology to secure both reliability and safety using the BMS data. Unlike other studies, we calculated the bus travel time between two bus stops by dividing the total travel length into 6 sections using 5 different measuring points. In addition, the optimal travel time for each bus route was proposed by analyzing the mean, standard deviation and coefficient of variation of the each section's measurement. This will ensure the reliability, safety and mobility of the bus operation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.3
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• pp.33-40
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• 2008

The TMO may contain two types of methods, time-triggered methods(also called the spontaneous methods of SpMs) which are clearly separated from the conventional service methods (SvMs). The SpM executions are triggered upon design time whereas the SvM executions are triggered by service request message from clients. In this paper, we describes the application environment as the patient monitor telemedicine system with TMO structure. Vital sign information web viewer systems is also the standard protocol for medical image and transfer. In order to embrace new technologies as telemedicine service, it is important to develope the standard protocol between different systems in the hospital, as well as the communication with external hospital systems. It is able to apply to remote medical examination and treatment. Through the proper data exchange and management of patient vital sign information, real time vital sign information management will offer better workflow to all hospital employee.