• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2603-2609
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• 2010

Currently at port, various trials about the improvement of operating method for raising operation efficiency of transferring equipment are made, but if the delay is occurred to quay crane due to individual team method in YT operation, the problem which even arranged YT should stop the work. Therefore, this study installed wireless location determining device within yard and measured the location of YT with real-time. Also, in order to raise the location determination effect, we converted operating method into pooling operation method and arranged YT. Through this study, we can trace the movement of YT with real-time and the work control method which anlayzes and evaluates congestion of yard objectively is prepared.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.527-531
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• 2003

Previous researches on scalability problem of distributed virtual environment (DVE) have been mainly focused on spatial partitioning of area of interest (AOI). Congestion phenomena by avatar groups in AOI have been neglected relatively. However, AOI congestion is highly related to scalability of DVT because it exhausts system resources such as network bandwidth and rendering time, and could be a bar to perform collaboration among participants. In this paper, this will be defined as the problem that must be solved for the realization of the scalable DVE, and a model will be proposed to measure and control congestion situation in AOI. The purposes of the proposed model are to prevent high density of participants in AOI, and to protect stable collaboration in DVE. For evaluation of the performance it is compared with a previous method by defining the resource cost model which is dynamically activated to AOI congestion.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.303-304
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• 2012

본 논문에서는 IEEE 802.11e 무선 애드 혹 네트워크 환경에서의 Throughput 향상을 위한 자원 할당 기법을 제안하였다. 제안하는 기법은 무선 애드 혹 네트워크에서 전송 홉 수 증가 및 네트워크 혼잡 상황에 따른 전송 손실을 최소화 하기 위한 기법으로 전송 큐 상태를 주기적으로 측정하여 큐에 쌓여지는 데이터의 가속도와 전송 큐에 쌓여있는 데이터의 비율을 측정한다. 측정된 가속도와 데이터의 비율을 통해 네트워크 상황에 적합한 자원을 할당하는 기법이다. 제안한 기법을 통해 무선 애드 혹 네트워크 환경에서 전송 홉 수 증가 및 네트워크 혼잡 상황에서의 성능 감소를 개선할 수 있었다.

• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.437-442
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• 2005

The measurement of RTT (Round Trip Time) can be used for the analysis of Internet congestion. However, simple measuring of RTT which measures only hun around time of a packet can not infer a packet forward/backward delay variation. In this thesis, we present a new algorithm which can be used for the estimation of forward/backward delay variation of packets. These delay variations are implication of network congestion state. In this algorithm, the reference forward/backward delay can be determined based on the minimum RTT value. The delay variation of each packet can be calculated by comparing reference delay with the packet delay. We verified our proposed algorithm by NS-2 simulation and delay measuring in a real network.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06d
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• pp.301-305
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• 2010

최근 무선 네트워크 서비스의 수요가 증가함에 따라 낮은 비용, 간편한 설치 그리고 높은 대역폭 특성을 가지는 무선랜 (WLAN)을 기반으로 한 사내 네트워크 구성이 학교 및 기업을 중심으로 증가하고 있다. 이로 인해 사내 네트워크를 통한 랩탑 (Laptop), 넷북 (Notebook), 스마트 폰 (Smart Phone), 그리고 UMPC (Ultra Mobile Personal Computer)등 휴대용 단말을 이용한 스트리밍 서비스의 수요가 증가하고 있다. 하지만 무선랜 환경은 사용자 이동에 의해 핸드오버가 발생할 경우, 이동할 대상 네트워크의 혼잡 상태를 고려하지 않는다. 따라서 이동할 네트워크에 빠르게 적응하지 못함으로써 패킷 손실에 의한 서비스의 불연속성 문제가 발생할 수 있다. 본 논문에서는 이러한 문제점을 해결하기 위해 핸드오버 이전에 이동 대상 네트워크의 혼잡 상태를 인지하여 전송률을 조절함으로써, 스트리밍 서비스의 불연속성 문제를 해결하는 적응적인 스트리밍 시스템을 설계 및 구현하였다. 제안하는 시스템은 핸드오버 이전에 이동 대상 네트워크의 가용대역폭을 측정하여 혼잡 상태를 인지하고, 측정한 가용대역폭 값을 기반으로 전송하는 프레임의 수를 우선순위에 따라 차등적으로 조절하여 전송률을 조절하였다.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.466-474
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• 2007

Asymmetric networks that the downlink bandwidth is larger than the uplink bandwidth may cause the degradation of the TCP performance due to the uplink congestion. In order to solve this problem, this paper designs and implements the Dynamic Segment Size Control mechanism which offers a suitable segment size for current networks. The proposed mechanism does not require any changes in customer premises but suppress the number of ACKs using segment reassembly technique to avoid the uplink congestion. The gateway which adapted the Dynamic Segment Size Control mechanism, detects the uplink congestion condition and dynamically measures the bandwidth asymmetric ratio and the packet loss ratio. The gateway reassembles some of segments received from the server into a large segment and transmits it to the client. This reduces the number of corresponding ACKs. In this mechanism, the SACK option is used when occurs the bit error during the transmission. Based on the simulation in the GEO satellite network environment, we analyzed the performance of the Dynamic Segment Size Control mechanism.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.1
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• pp.9-15
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• 2005

Congestion control is an important research area in computer network. In this paper, I provided strategy of congestion pricing with differentiated services. And, suggested forecasting model of access that considered differentiated pricing, delay time, satisfaction using logistic regression. In a forecasting model of access with logistic regression technique, it is shown that coefficient of determination using suggested model is $70.7\%$.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.2
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• pp.82-93
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• 1997

교통의 발달 및 빈번한 문화와 정보의 교류는 옥외 recreation 활동 참여의 다양한 인종적 구성을 가져왔다. 이 연구의 목적은 옥외 recreation 활동의 하나인 스키장에서 이용 밀도에 대한 선호도를 문화·인종간의 혼잡규범적 차이로서 해석하는데 있다. 한국의 용평 스키장과 미국 Hunter Mt. 스키장에서 한국인, 주한 미국인, 미국인, 재미 한인 들을 대상으로 이용밀도에 관한 선호도를 측정하기 위한 설문조사를 실시한 결과, 1,157부의 설문지를 회수하여, 문화·인종간의 차이를 규명하기 위하여 Kruskal-Wallis test 실시하였다. 연구의 결과로서 재미한국인의 이용밀도에 대한 선호도가 동일 인종인 한국인집단보다 사회 문화적으로 공통성이 있는 미국인집단에 더 유사하였으며 그와 반대로 재한미국인집단은 동일 인종집단인 미국 집단과 차이가 없었다. 이 결과는 혼잡 규범으로서의 이용 밀도의 선호도가 이용자의 개인적 특성 및 인종적 특성뿐만이 아니라 문화인종적 특성에 영향을 받는다는 결론을 얻었다.

• Journal of KIISE
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• v.43 no.8
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• pp.919-926
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• 2016

In a wireless network, TCP causes the performance degradation because of mistaking packet loss, which is caused by characteristics of wireless link and throughput oscillation due to change of devices connected on a limited bandwidth. Delay based TCP is not affected by packet loss because it controls window size by using the RTT. Therefore, it can solve the problem of unnecessary degradation of the rate caused by misunderstanding reason of packet loss. In this paper, we propose an algorithm for improving the remaining problems by using delay based TCP. The proposed scheme can change throughput adaptively by adding the RTT, which rapidly reflects the network conditions to BaseRTT. It changes the weight of RTT and the increases and decreases window size based on the remaining amount of the buffer. The simulation indicated that proposed scheme can alleviate the throughput oscillation problem, as compared to the legacy TCP Vegas.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.923-929
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• 2021

TCP communication and packet communication require transmission control technology to ensure high quality and high reliability. However, in the case of real-time data transmission, an inefficient transmission problem occurs. In order to overcome this problem and transmit the packet reliability, in general, early congestion control using the buffer level as an index was used. Control of the congestion control point and the cancellation point is delayed because the point at which congestion is controlled is based on the buffer level. Therefore, in this paper, not only the buffer level indicator, but also the ideal buffer level, which determines the packet discard probability, is classified so that the transmission rate and buffer level that measure network congestion are close to the level above the optimal setting. As a result, it was shown that the average buffer level can be directly controlled by maintaining the average buffer level by the ideal buffer level set in the experiment to prove the proposed method.