• Journal of KIISE:Computing Practices and Letters
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• v.12 no.1
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• pp.78-89
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• 2006

In development of network-enabled consumer electronics, much of the time and effort is spent analyzing and solving network performance problems. In this paper, we define an instance of such problems discovered while developing a commercial home network gateway. We then analyze its cause and propose a solution mechanism. Our home network gateway uses art asymmetric link (ADSL) and suffers from an undesirable phenomenon where downlink traffic interferes with upload speed. We call this phenomenon the network performance interference problem. While this problem can easily be confused with receive livelock caused by packet contention at the input queue, we and that this is not the case. By performing extensive experiments and analysis, we reveal that our problem is caused by packet contention at the output queue and certain intrinsic characteristics of TCP. We devise an ACK-separation queuing mechanism for this problem and implement it in the home network gateway Our experiments show that it effectively solves the problem.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.75-81
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• 2012

This paper has proposed Message Count Control Mechanism based Link State Update(LSU) Algorithm that has not had a strong influence on the depreciation of QoS routing performance. Most existing LSU algorithms have the limit that cannot control the count of LSU message. Especially, adaptive algorithms have a bad performance when traffic are excessive and fickle. We classify as the importance of LSU message that have a influence on available bandwidth and determine the transmission of the message according to update rate per a unit of time. We have evaluated the performance of the proposed model and the existing algorithms on MCI simulation network using the performance metric as the QoS routing blocking rate and the mean update rate per link, it thus appears that we have verified the performance of this algorithm.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.219-226
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• 2012

Since OFDM(Orthogonal Frequency Division Multiplexing) technology is applied into LTE(Long Term Evolution)/LTE-Advanced system, it is important to estimate the spectrum sharing and to analyze interference in LTE system based on the characteristics of frequency assignment. Therefore, in this paper, a study on the adjacent channel interference between two operators/systems to provide LTE services. For co-existence of LTE systems, the relative capacity loss and the relative throughput loss in uplink and downlink have been simulated to evaluated ACIR(Adjacent Channel Interference Ratio) values with 5% loss rate. Some parameters such as the location of user, aggressor bandwidth, and the separation offset affect the required ACIR value for spectrum sharing, and these results and interference analysis schemes in this article can provide reliable reference for LTE RF standardization and efficient frequency utilization in future.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.61-68
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• 2010

Korea has made a plan to allocate CH 14~CH 51 (470 MHz~698 MHz) for DTV transition. Therefore, It is a necessary to take account compatibility between DTV service and other potential services. This paper assumes that DTV service operates on CH 51(692 MHz~698 MHz) and IMT service operates on CH 52(698 MHz~704 MHz), and then analyzes compatibility between DTV service and IMT service with Spectrum Engineering Advanced Monte Carlo Analysis Tool(SEAMCAT). The interference probability from IMT service to DTV service and capacity loss of IMT service due to interference from DTV service is studied, respectively. For the simulation, four interference cases in four different scenarios are considered. With considering the depolarization factor, a guard band of 8 MHz is required in the case of between IMT service downlink(DL) and DTV service, in the case of between IMT service uplink(UL) and DTV service, a guard band of 6 MHz is needed for the worst case of urban scenario on consideration of more then 15 dB increase of IMT system base station(BS) receiver blocking level.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.298-306
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• 2015

In this paper, we propose an efficient resource allocation scheme for the integrated satellite/terrestrial networks. The proposed scheme is a frequency sharing technique to mitigate the inter-component interferences which can be generated between a satellite beam and terrestrial cells that are operated in the same frequency. The proposed dynamic resource allocation scheme can mitigate the total inter-component interference by optimizing the total transmission power and it can expect a result of which can lead to an increase in capacity. In such a system, the interference situation can be affected by the distributed traffic demands or up/down link communications environments. In this point of view, we evaluate the performance of the total consumed power, the amount of inter-component interference with respect to different traffic distributions and interference environments between the satellite beam and terrestrial systems.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.44-52
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• 2010

The most popular world wide web traffic in the Internet uses TCP as the transport layer protocol. Since TCP utilizes the single path, it can not communicate with the correspondent host during the link-down. On the other hand, SCTP can still communicate with the other SCTP entity by using alternate path even while the primary path is down. Most of previous studies have conducted the performance comparison research between TCP and SCTP by using typical file transfer. Since web traffic with self-similarity is characterized by the packet inter-arrival times and shape parameter affecting the size of web file in the Pareto distribution, it is necessary to perform the experiments considering these parameters. This paper aims to compare the throughput between TCP and SCTP while varying parameters reflecting the web traffic characteristics in link-down environment. Experimental results for web traffic using NS-2 simulator show that the throughput of SCTP using multi-homing is better than that of TCP. Simulation also shows that TCP is more affected than SCTP by mean inter-arrival and shape parameters with regard to the web traffic. These results can be applied to estimate the performance variation of web traffic due to the duration of link-down.

• Journal of the Korean Society for information Management
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• v.33 no.1
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• pp.293-316
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• 2016

This study aims to improve bibliographic data of public libraries by linking service data, which are produced out of library service programs. Service data collected from the seven award-winning public libraries were selected and analyzed. A Bibliographic Framework is used for linking bibliographic data and service data. Interfaces are also suggested for the two-way data linking. The results can be used to obtain 1) selective and value-added bibliographic data, 2) bibliographic data updated continuously throughout the lifecycle, 3) structured service data for preservation and sharing, and 4) bibliographic data linked to the additional external linked data.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.218-224
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• 2013

Uplink overflow in WMSN (Wireless Multimedia Sensor Networks) aggravates the resource consumption, delay, and traffic congestion. This paper proposes a new traffic congestion control mechanism using popularity. The proposed mechanism controls congestions by dispersing the media traffic, and it control fairly packets according to priority. This paper proposes PQS (Packet Queue Scheduler) to control fairly packets, and the proposed mechanism provides a fair opportunity to all sensor nodes without a specific location. The simulation results show that the proposed mechanism achieves improved performance in throughput, delay ratio, link quality, and buffer queue control ratio compared with those of other existing methods.

• The Journal of Korean Institute of Information Technology
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• v.17 no.5
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• pp.1-12
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• 2019

Unlike existing Open APIs, Linked Data are made as a huge intelligent base to perform high-level SPARQL queries, and it is possible to create efficiently a new content by mashuping different information from various datasets. This paper implements a responsive web application for location-based semantic search. We mashup DBpedia, a kind of Linked Data, and GoogleMap API provided by Google, and provide a semantic browser function to confirm detail information regarding retrieved objects. Our system can be used in various access environments such as PC and mobile by applying responsive web design idea. The system implemented in this paper compares functional specifications with existing systems with similar functions. The comparison results show the superiority of our system in various aspects such as using semantic, linked-based browser, and mashup function.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.101-103
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• 2022

자율운항선박은 센서, IoT, 빅데이터, AI, 플랫폼 등 고도의 ICT 요소 기술이 필요한 미래 유망 산업 분야이다. 특히 선박 내부장치로 부터 수집된 정보와 선박 주변의 해상 데이터가 증가될수록 선박 대 선박 및 선박 대 육상 간 정보 교환 체계인 해상통신망의 중요성은 커질수 밖에 없다. 해양수산부는 2020년 세계 최초로 대한민국 연안으로부터 최대 100km 까지 해역을 LTE(Long Term Evolution) 통신체계로 구축한 바 있다. 본 논문은 초고속 해상무선통신망(LTE-Maritime)이 자율운항선박의 주요 통신 기술로써 활용되기 위해 우선적으로 고려할 사항을 타 해상 무선통신 기술과의 연계, 업링크 및 항내 통신품질의 향상 관점으로 살펴보고자 한다. 이를 위해 LTE-M. 망의 무선설비 다각화 사업으로 추진중인 해양 드론용 송수신기의 실해역 성능 시험을 통해, 선박과 육상 간 정보 교환에 있어 상호운용성 시험의 중요성을 재고해 보고, 해상 무선통신 체계의 신뢰성 및 호환성을 확보하기 위한 무선품질지표, 상호운용성 시험 방법 등을 제시하고자 한다.