• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1349-1358
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• 2009

Because of the limitation of supporting power, the current WSN(Wireless Sensor Network) Technologies whose one of the core attributes is low power consumption are the best solution for shipping container networking in stack environment such as on vessel. So it is effective to use the Wireless Sensor Network Technology. In this case, many nodes join in the network through a sink node because there are difficulties to get big money and efforts to set up a lot of sink node. It needs clustering-based proactive protocol to manage many nodes. But it shows low reliability because they have effect on radio frequency in metal obstacle environments(interference, distortion, reflection, and etc) like the intelligent container. In this paper, we proposed an improved Modified LEACH Protocol for stableness radio frequency environment. In the proposed protocol, we tried to join the network and derived stable topology composition after the measuring of link quality. Finally, we verified that the proposed protocol is composing more stable topology than previously protocol in metal obstacle environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3B
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• pp.204-211
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• 2012

Wireless Mesh Network (WMN) has drawn much attention due to wide service coverage with low system cost. However, WMN suffers from high bit error rate, which provides different link capacity among wireless mesh routers. The conventional routing metrics select the path based on link quality. The link with the best quality is preferred as the data transmission path, and they becomes the bottleneck links, which leads to network performance degradation. In this paper, we propose a routing metric that considers the available bandwidth and the number of nodes suffering congestion in the path. Through computer simulations, we verified that the proposed routing metric outperforms the existing routing metrics in terms of average transmission delay, packet loss, system throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1623-1635
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• 2011

Fourth-generation (4G) cellular communication systems must provide different quality-of-service (QoS) to users according to the service type, membership class, and usage case of each user. For the purpose of user's QoS differentiation, we propose an enhanced uplink random access scheme for bandwidth request. More specifically, we divide a bandwidth request channel into two parts: One is a primary region and the other is a secondary region. Then, each region has a unique minimum access class that allows only specific users to perform random access through that region. By doing so, we can reduce collision probability and increase the success probability of bandwidth request. From the perspective of standardization, we presented this scheme in the IEEE 802.16m Session #66 held on March 2010. As a result, the concept of the proposed scheme and required messages were defined in the 802.16m standard.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.141-148
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• 2013

Automated classification systems which utilize machine learning develops classification models through learning process, and then classify unknown data into predefined set of categories according to the model. The performance of machine learning-based classification systems relies greatly upon the quality of features composing classification models. For textual data, we can use their word terms and structure information in order to generate the set of features. Particularly, in order to extract feature from Web documents, we need to analyze tag and hyperlink information. Recent studies on Web document classification focus on feature engineering technology other than machine learning algorithms themselves. Thus this paper proposes a novel method of incorporating feature selection and weighting which can improves classification models effectively. Through extensive experiments using Web-KB document collections, the proposed method outperforms conventional ones.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1609-1617
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• 2013

TFRC(TCP-Friendly Rate Control) has a performance degradation in wireless networks because it performs congestion control by judging all the losses occurred in wireless networks as a congestion indicator. It is also degraded by the increased Round Trip Time(RTT) due to packet retransmission and contention overhead in the link layer. In this paper, we propose an adaptive rate control scheme based on cross-layer to improve the quality of streaming services in the wireless networks. It provides new RTT estimation and loss discrimination methods to improve transmission rate of TFRC. The simulation results show that the proposed scheme can improve the performance of TFRC.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.411-419
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• 2012

This study is focusing on factors influencing trust in power blogs, and the effect of trust on users' attitude and purchase intention. The research model is based on the theory of online trust formation process and content quality. The statistical analysis was conducted through the survey of 122 power blog users. Research findings show that scope, accuracy, uniqueness, links, quality of wring, and reputation of power blogs significantly affect trust. Also, trust was found to have a significant influence on the users' attitude and purchasing intention on products/services.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.360-368
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• 2008

In this paper, in order that the various QoS(Qualify of Service)s that are required by different traffic class are guaranteed in the random access channels in multi-service multi-user OFDMA systems, the backoff-based random access algorithm is proposed and corresponding performance is analyzed in terms of the access success probability, the throughput, the average delay and the blocking probability. Through the numerical analysis, it is shown that the proposed backoff-based random access algorithm can provide the differentiated QoSs to random access attempts according to their service class.

• 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.

• Journal of IKEEE
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• v.27 no.4
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• pp.617-623
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• 2023

With the evolution of communication networks, there is a growing demand for stable high-speed data connections to support services relying on large-capacity data. The increasing volume of packet data aggregated from user devices underscores the significance of quality diagnostics for the backhaul network, an intermediate link transmitting data to the core network. This paper conducts empirical research on techniques to diagnose issues within the backhaul network through practical case studies, through diagnosing various factors such as circuit bandwidth, speed disparities within switches, network segment-specific buffer sizes, routing policies, among other factors that could potentially cause RTT (Round Trip Time) delays and performance degradation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.3
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• pp.71-75
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• 2018

In this paper, we study the secrecy outage probability when using jammer in a relay system based on decode-and-forward. The jammer may be selected among the relays not selected to increase the security capacity in the physical layer so as to generate intentional noise. Jammer noise can equally interfere with the receiver and eavesdropper but can enhance the physical layer security by selecting an optimal jammer that makes the channel quality between the sender-eavesdropper links worse than the channel of the sender-receiver link. In this paper, we compute the theoretical formula of the secrecy outage probability with and without jammers, and compare the theoretical value with the simulation value to prove that the equation is valid.