• 한국도로학회논문집
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• 제14권5호
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• pp.31-45
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• 2012

PURPOSES: In Korea, rapid maintenance of distressed concrete pavement is required to prevent traffic jam of the highway. Asphalt concrete overlay has been used as a general maintenance method of construction for aged concrete pavement. AC overlay on existing concrete pavements experience various early distresses such as reflection crack, pothole and rutting, due to different physical characteristics between asphalt overlay and existing concrete pavement. Bonded concrete overlay(BCO) is a good alternative since it has advantages that can reduce various distresses during the service life since overlay material has similar properties with existing concrete pavements. Recently, BCO which uses the ultra rapid harding cement has been applied for maintenance of highway. BCO has advantage of structural performance since it does monolithic behave with existing pavement. Therefore, it is important to have a suitable bond strength criteria for securing performance of BCO. Bond strength criteria should be larger than normal tensile stress and horizontal shear stress occurred by traffic and environmental loading at bond interface. Normal tensile stress and horizontal shear stress need to estimated for the establishment of practical bond strength criteria. METHODS: This study aimed to estimate the bond stresses at the interface of BCO using the three dimensional finite element analysis. RESULTS: As a result of this study, major failure mode and maximum bond stress are evaluated through the analysis of normal tensile stress and horizontal shear stress for various traffic and environmental load conditions. CONCLUSIONS: It was known that normal tensile stresses are dominated by environmental loading, and, horizontal shear stresses are dominated by traffic loading. In addition, bond failure occurred by both of normal tensile stresses and horizontal shear stresses; however, normal tensile stresses are predominated over horizontal shear stresses.

• 한국통신학회논문지
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• 제26권11C호
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• pp.140-147
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• 2001

본 논문에서는 효율적인 QoS 라우팅을 위하여 선계산(precomputation) 방식의 경로계산에서 자원 비용 산정 방식을 제안하여 전체 네트워크 자원의 최적 사용과 네트워크 자원의 부하 균등을 가능하게 하였다. 도메인으로 분할된 대규모 네트워크의 QoS 라우팅에서 transit traffic을 위한 경로를 선계산 방식으로 설정하고, 이들 경로들의 예약 가능성을 높이기 위해 자원 예약 측면에서 가장 좋은 K개의 경로들을 부하균등을 고려하여 계산한 후 경로 선택확률에 따라 경로를 설정하는 방안을 제안하였다. 그리고 동일한 자원 비용 산정 방식을 transit traffic과 intra traffic에 모두 적용하여 도메인간 라우팅(inter-domain routing)과 도메인내 라우팅(intra-domain routing)을 무리 없이 연계하면서 transit traffic을 우선으로 하는 방식을 제안하였다. 끝으로 부하균등 비용산정을 분석하기 위한 시뮬레이션을 수행하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.75-77
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• 2005

An integrated I&C architecture for nuclear power plants is designed by the systems and devices being developed in a project. Its design reference is the APR1400 that was design certified in Korea. Digital equipment and several kinds of data communication networks (DCN) are used. To confirm the validity of DCN based architecture design, the traffic loads fur each network were calculated assuming the anticipated maximum traffic condition. The analysis showed that the utilizations of all networks satisfied the design requirements.

• 전자공학회논문지A
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• 제31A권7호
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• pp.1-16
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• 1994

In this paper, we propose a new multiple access scheme for VSAT(Very Small Aperture Terminal) data communications. The proposed scheme has better performance in terms of delay throughput than Controlled Multiaccess Scheme which has excellent performance. The proposed scheme use the spare reservation method, adaptation method to offered load, and fixed bandwidth reservation method. In this paper, we analyze the performance using simple queueing model and present the simulation results. When network traffic is very low, the new scheme and the controlled multiaccess scheme have almost the same access delay characteristic. As the network load becomes higher, the new scheme's access delay gain becomes larger. Futhermore, even when the network traffic is very high it is possible to access satellite link within the delay similar to one round-trip delay. In addition to access delay performance enhancement, the new scheme has facility that supports fixed bandwidth reservation. So it shows more enhanced performance in the environment that stream traffic is dominant such as in VSAT communication environment.

• 전자공학회논문지A
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• 제32A권3호
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• pp.411-417
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• 1995

Packet switching is an important aspect of ISDN. In the TDX-10 switching system, which is being developed as an ISDN exchange in Korea, the packet switching function is implemented on the basis of Case B scenario of X.31. After implementing the packet switching function the performance test must be executed to check whether the design objectives of performance are satisfied or not. However, it is not easy to set up test environment for performance measurement under full load conditions. This paper presents the design of the traffic generator which enables us to do performance test of the TDX-10 packet handler under full load conditions. To generate packet traffic we change only software programs without any change of the hardware system of the packet handler.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5449-5464
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• 2018

Recent works have validated the possibility of reducing the energy consumption in wireless heterogeneous networks, achieved by switching on/off some base stations (BSs) dynamically. In this paper, to realize energy conservation, the discrete time Markov Decision Process (DTMDP) is developed to match up the BS switching operations with the traffic load variations. Then, an asynchronous decision-making algorithm, which is based on the Bellman equation and the on/off priorities of the BSs, is firstly put forward and proved to be optimal in this paper. Through reducing the state and action space during one decision, the proposed asynchronous algorithm can avoid the "curse of dimensionality" occurred in DTMDP frequently. Finally, numerical simulations are conducted to validate the effectiveness and advantages of the proposed asynchronous on/off strategies.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2006년도 추계 종합학술대회 논문집
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• pp.61-64
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• 2006

이동성 지원 네트워크에 대한 요구가 증가함에 따라 IP 기반의 이동성 지원 프로토콜들이 제안되었다. MAP을 이용해 마이크로 이동성을 관리하는 HMIPv6는 MAP이 관리하는 도메인 내에서의 단말 이동에 대해 효율적인 이동성 지원을 위한 방안들을 제시하고 있지만, MAP으로 트래픽이 집중되는 문제점을 가지고 있다. 본 논문에서는 계층적 Mobile IPv6에서 MAP에 집중되는 트래픽을 효율적으로 분산하는 기법을 제안한다. 제안 기법에서는 두개 이상의 MAP을 선정하고 Active MAP과 Passive MAP으로 구분한다. 제안 기법은 크게 Active MAP과 Passive MAP간의 상태변경과 특정 MAP에서 트래픽으로 인한 부하가 일어날 경우 부하 분산을 위한 MAP간의 동작을 정의한다.

• 한국통신학회논문지
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• 제31권12A호
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• pp.1189-1197
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• 2006

Ultra-wideband(UWB) is a killer technology for short-range wireless communications. In the past, most of the UWB research focused on physical layer but the unique characteristics of UWB make it different to design the upper layer protocols than conventional narrow band systems. Cross-layer protocols have received high attention for UWB networks. In this paper, we investigate the performance of two physical layer schemes: Time Hopping Binary Pulse Position Modulation(TH-BPPM) and Time Hopping Binary Pulse Amplitude Modulation (TH-BPAM) with proposed private MAC protocol for UWB ad-hoc networks. From pulse level to packet level simulation is done in network simulator ns-2 with realistic network environments for varying traffic load, mobility and network density. Our simulation result shows TH-BPAM outperforms TH-BPPM in high traffic load, mobility and dense network cases but in a low traffic load case identical performance is achieved.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.2875-2893
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• 2015

Existing coding aware routing algorithms focused on novel routing metric design that captures the characteristics of network coding. However, in packet coding algorithm, they use opportunistic coding scheme which didn't consider the queue state of the coding node and are equivalent to the conventional store-and-forward method in light traffic load condition because they never delay packets and there are no packets in the output queue of coding node, which results in no coding opportunity. In addition, most of the existing algorithms assume that all flows participating in the network have equal rate. This is unrealistic since multi-rate environments are often appeared. To overcome above problem and expand network coding to light traffic load scenarios, we present an enhanced coding-aware routing algorithm based on queue state and local topology (OQMCAR), which consider the queue state of coding node in packet coding algorithm where the control policy is of threshold-type. OQMCAR is a unified framework to merge single rate case and multiple rate case, including the light traffic load scenarios. Simulations results show that our scheme can achieve higher throughput and lower end-to-end delay than the current mechanisms using COPE-type opportunistic coding policy in different cases.

• 한국철도학회논문집
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• 제19권5호
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• pp.663-671
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• 2016

본 연구에서는 교통카드자료를 기반으로 한 김경민 외[1]의 승객경로추적 방법을 이용하여 서울지하철 9호선 2단계 개통에 따른 급행열차 선택에 대한 변화를 분석하였다. 분석결과 2단계 개통 전과 비교하였을 때, 1단계 구간 기존 승객들의 급행열차 선택 비율은 변하지 않음을 확인하였다. 개통 전 후로 나누어 각각에 대한 다항로짓모형을 개발하였고 개통 전 후 모형의 전이성을 확인하였다. 하지만, 급행열차에 대한 선택이 높은 장거리 승객의 증가로 인해 2단계 개통 후 급행열차의 혼잡도가 약 6.7% 상승하였고 일반열차와의 혼잡도 차이는 증가하였다.