• 전자공학회논문지
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• 제51권8호
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• pp.58-65
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• 2014

최근 이슈가 되고 있는 사물인터넷(Internet of Things)에서는 모든 사물들이 정보를 주고 받고 또한 이에 반응하는 형태의 서비스를 기반으로 한다. 이러한 사물 인터넷 서비스들은 가장 기본적으로 정보 노드로부터의 정보를 받아서 이에 대한 반응을 하는 것이 주가 되는데, 이러한 이벤트에 기반한 서비스를 수행하는데 있어서 정보노드들이 주는 정보들을 어떻게 처리하는가는 사물인터넷에서의 서비스 신뢰도에 중요한 요인이 된다. 이에 본 논문에서는 분산 결정 방식의 사물인터넷 구조에서 센싱 정보등을 전달하는 정보노드로부터 정보를 받아서 서비스를 수행하는 액츄에이터등의 수행노드들의 서비스 신뢰성 확보와 에너지 효율성 증대를 위한 방법을 제안토록 한다.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.291-299
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• 2016

To enhance network efficiency, named-data networking (NDN) implements data caching functionality on intermediate network nodes, and then the nodes directly respond to request messages for cached data. Through the processing of request messages in intermediate node, NDN can efficiently reduce the amount of network traffic, also solve network congestion problems near data sources. Also, NDN provides a data authenticate mechanism so as to prevent various Internet accidents caused from the absence of an authentication mechanism. Hence, through applying NDN to various smart IT convergence services, it is expected to efficiently control the explosive growth of network traffic as well as to provide more secure services. Basically, it is important factors of NDN which data is cached and where nodes caching data is located in a network topology. This paper first analyzes previous works caching content based on the popularity of the content. Then ii investigates the hitting rate of caches in each node of a network topology, and then propose an improved caching scheme based on the result of the analyzation. Finally, it evaluates the performance of the proposal.

• 산업공학
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• 제13권3호
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• pp.416-423
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• 2000

This paper considers a web-based order processing system under SCM environment. Following the framework of B2B electronic commerce, we focus on activities closely related to order handling within the supply chain. We also try to integrate the order processing system with the overall information system of the company. The methodology is applied to the case of H company and a prototype system is designed. This study analyzes the current product estimate and order handling process in the point of view of both the purchasing and the selling companies. It intends improvement by changing the existing closed way of request and offering estimate through fax or VAN into an open way using internet. For this, a company should be registered on the order site of internet. Then it can request estimate, take estimate, and handle order through internet adopting the concept of electrical commercial transaction.

• Journal of Communications and Networks
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• 제8권2호
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• pp.212-219
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• 2006

In this paper, a new turbo codes-based hybrid automatic repeat request (TC-HARQ) scheme with segment selective repeat (SSR) is proposed. The main strategy is, upon retransmission, to repeat the data that are most important for the next round of decoding based on the distribution of residual errors after current decoding. The performance in terms of reliability and throughput is analyzed. To adapt to correlated fading channels where an inter-leaver is always employed before transmission, we further modify the SSR strategy so that data having experienced correlated deep fading are selected for retransmission. Finally, this proposed scheme is applied to the wideband code division multiple access (WCDMA) system under frequency selective fading channels. Simulation results demonstrate that in all single and multiple user cases, SSR-based TC-HARQ leads to significant throughput improvement with similar bit error rate (BER) performance as compared to type-I TC-HARQ.

• 한국융합학회논문지
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• 제1권1호
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• pp.17-21
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• 2010

본 논문에서는 실시간 웹 서비스 시스템에서 과부하를 조절하는 기법을 제안한다. 기존의 많은 기법은 단순히 웹 연결 수를 조절하여 과부하를 방지한다. 이는 웹서버의 요청 처리를 위한 추가적인 웹 태스크의 생성을 조절하는 것만 가능하고, 이미 생성된 웹 태스크나 내부 디바이스의 최신 상태를 알려주기 위해서 주기적 동작하는 내부의 실시간 태스크 등에 대해서는 과부하 방지를 위한 아무런 조치를 취하고 있지 않다. 본 논문에서는 주기적 동작하는 내부의 실시간 태스크 등에 대해서도 동적으로 부하를 반영할 수 있는 제어기를 설계한다. 설계된 제어기를 적용한 피드백제어 시스템을 구성하여 안정된 부하 조절이 가능함을 확인하였다.

• Journal of Communications and Networks
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• 제8권4호
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• pp.442-450
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• 2006

Inter-operability between heterogeneous radio access technologies (RATs), in the sense of seamless vertical han-dover (VHO) support with common radio resource management (CRRM) functionalities, has recently attracted a significant research attention and has become a prominent issue in standardization fora. In this paper, we formulate the problem of load balancing between cooperative RAT's as a mathematical program and by trading off a pre-defined delay tolerance per request we propose a vertical handover batch processing (VHBP) scheme. To quantify the performance of the proposed VHBP scheme we compare it with a baseline processing scheme, where each VHO request is processed independently under a number of different network scenarios. Numerical investigations reveal significant net benefits of the proposed scheme compared with the baseline, both in terms of achieved load balancing levels but also with regard to the acceptance rate of the VHO requests.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.3-4
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• 2008

We propose an efficient uplink bandwidth request-allocation algorithm for variable-rate real-time service in IEEE 802.11 broadband wireless access networks. By introducing a notion of target delay under the framework of dual feedback, the proposed algorithm can assure the desired level of QoS while minimizing wastage of bandwidth allocation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.974-979
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• 2003

As recently optical communication industry is developed, request of optical communication part is increased. Ferrule is very important part which determines transmission efficiency and quality of information in the optical communication part. Most of ferrule processes are grinding which request high processing precision. Particularly, concentricity and cylindricity of inner and outer diameter is very important. The co-axle grinding process of ferrule is to make its concentricity all of uniform before centerless grinding. Surface integrity of ferrule is affected by kind of grinding wheels, grinding conditions, and characteristic of workpiece and equipment. In this study, surface integrity of workpiece according to change of grinding wheel speed, feed rate, regulating wheel speed and grinding force is investigate to improve the concentricity and roundness of ferrule from many experiments.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.98-101
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• 1999

Proposed in this paper is an algorithm in which the maximum value of transmission delay due to collision during the reservation request minicell transmission in the uplink period is guaranteed for each traffic type in order to support real time multimedia traffic in wireless ATM environment. Also proposed is a scheme that uses minislots in which dynamic parameters can be transmitted without collision by using only 1-bit piggyback flag of each cell. Setting the piggyback flag is determined according to traffic characteristics and buffer length of each mobile terminal. It is shown that there has been a great improvement in performance of the proposed algorithm through performance analysis using simulation although the algorithm has little overhead.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.43-48
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• 2003

This paper presents a comparative evaluation of a modified version (A-Protocol) of the Distributed-Queueing Request Update Multiple Access (DQRUMA)Multi-Code Code Division Multiple Access (MC-CDMA) protocol and an enhanced version (P-Protocol) of the DQRUMA/MC-CDMA protocol with a lattice pool for request accesses (LPRA) scheme in a packet-based voice traffic environment. Analytical results agree with the simulation ones and show that the P-Protocol outperforms the A-Protocol in terms of the packet loss rate for voice traffic.