• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.1
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• pp.105-122
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• 2011

The fundamental design goal of wireless sensor MAC protocols is to minimize unnecessary power consumption of the sensor nodes, because of its stringent resource constraints and ultra-power limitation. In existing MAC protocols in wireless sensor networks (WSNs), duty cycling, in which each node periodically cycles between the active and sleep states, has been introduced to reduce unnecessary energy consumption. Existing MAC schemes, however, use a fixed duty cycling regardless of multi-hop communication and traffic fluctuations. On the other hand, there is a tradeoff between energy efficiency and delay caused by duty cycling mechanism in multi-hop communication and existing MAC approaches only tend to improve energy efficiency with sacrificing data delivery delay. In this paper, we propose two different MAC schemes (ADS-MAC and ELA-MAC) using closed-loop control in order to achieve both energy savings and minimal delay in wireless sensor networks. The two proposed MAC schemes, which are synchronous and asynchronous approaches, respectively, utilize an adaptive timer and a successive preload frame with closed-loop control for adaptive duty cycling. As a result, the analysis and the simulation results show that our schemes outperform existing schemes in terms of energy efficiency and delivery delay.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.943-946
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• 2004

최근에 중등학교 학내 전산망에서 동영상 위주의 멀티미디어 학습 자료를 이용한 학습이 많아짐에 따라, 실제 수업 시간이나 자율 학습 시간에 동영상 학습 자료를 활용했을 때 트래픽 특성이 구체적으로 어떻게 나타나는 지를 정량적으로 규명하는 것이 요구된다. 이에 본 논문에서는 고등학교 1개교와 중학교 1개교에 대해 동영상 학습 자료를 이용한 학습 시 학내 전산망에서 나타나는 트래픽 특성을 트래픽 분석 도구를 이용하여 분석하였다. 특히, 학교 내에 자체 웹 서버의 유무, 컴퓨터 접속 대수 등을 주요 변인으로 하여 동영상 실행 시 나타나는 현상들에 대한 측정 결과들을 제시하였다. 측정 결과로부터 다음과 같은 특성들을 얻어낼 수 있었다. 첫째, 학교 내에 자체 웹 서버의 유무가 전송 트래픽 량에 상당한 영향을 주었다. 둘째, 동시 컴퓨터 접속 대수의 증가가 끊김 현상과 같은 트래픽 특성에 영향을 주었다. 이러한 측정 및 분석 결과를 볼 때, 적게는 수십 명 많게는 수백 명의 학생이 동시에 인터넷을 통해 학습을 한다면 학내 전산망의 구성 형태나 동시 접속자 수에 따라 원활한 학습을 가져오지 못하고 많은 문제를 가져 올 것으로 예상되었다.

• Journal of Internet Computing and Services
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• v.20 no.2
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• pp.9-19
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• 2019

Service and users over the Internet are increasing rapidly. Cyber attacks are also increasing. As a result, information leakage and financial damage are occurring. Government, public agencies, and companies are using security systems that use signature-based detection rules to respond to known malicious codes. However, it takes a long time to generate and validate signature-based detection rules. In this paper, we propose and develop signature based detection rule generation and verification systems using the signature extraction scheme developed based on the LDA(latent Dirichlet allocation) algorithm and the traffic analysis technique. Experimental results show that detection rules are generated and verified much more quickly than before.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4573-4594
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• 2020

Announcement protocol in Internet of Vehicles (IoV) is an intelligent application to enhance public safety, alleviate traffic jams and improve transportation quality. It requires communication between vehicles, roadside units and pedestrian to disseminate safety-related messages. However, as vehicles connected to internet, it makes them accessible globally to a potential adversary. Safety-related application requires a message to be reliable, however it may intrude the privacy of a vehicle. Contrarily, if some misbehaviour emerges, the malicious vehicles must be able to traceable and revoke from the network. This is a contradiction between privacy and accountability since the privacy of a user should be preserved. For a secure communication among intelligent entities, we propose a novel announcement protocol in IoV using group signature. To the best of our knowledge, our work is the first comprehensive construction of an announcement protocol in IoV that deploys group signature. We show that our protocol efficiently solves these conflicting security requirements of message reliability, privacy and accountability using 5G communication channel. The performance analysis and simulation results signify our work achieves performance efficiency in IoV communication.

• Journal of Software Assessment and Valuation
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• v.15 no.2
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• pp.67-72
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• 2019

The recent explosion of data traffic, including cloud services, coupled with the Internet penetration has led to a surge in the need for ultra-fast optical networks that can efficiently connect the data center's reconfiguable resources. In this paper, the algorithms for controlling switching cell operation in the optical switch connection structure are proposed, and the resulting performance is compared and analyzed through simulation. Performance analysis results showed that the algorithm proposed in this paper has improved the probability of successful multi-connection setup by about 3 to 7% compared to the existing algorithm.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.23-32
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• 2015

The advanced receiver which can manage inter-cell interference is required to cope with the explosively increasing mobile data traffic. 3rd Generation Partnership Project (3GPP) has discussed network assisted interference cancellation and suppression (NAICS) to improve signal-to-noise-plus-interference ratio (SINR) and receiver performance by suppression or cancellation of interference signal from inter-cells. In this paper, we propose the novel hybrid receiver Full Suppression Cancellation (FSC) to reduce the interference from neighbor cell in backhaul system. The proposed receiver can suppress and cancel the interference by combining Interference Rejection Combining (IRC) with Successive Interference Cancellation (SIC). We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced system. Simulation results show that the proposed receiver can improve error rate and throughput of conventional system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1472-1480
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• 2016

When disasters such as earthquake, flood, typhoon, fire and terrorism are occurred a video management system is required which can shoot video on the disaster site, and send it to a server located in the command center that can grasp at a glance the site conditions. In this paper, to know the performance elements information needed to construct the video management system. we presented a method of configuring an ad hoc network based on Wi-Fi direct communication. And we also evaluated the performance through built of environment for the video management system. The evaluated performance test items are 'packet flow tests according to the video compression ratios and the image sizes', 'packet flow tests according to the distance and traffic tests', 'packet flow tests according to whether LOS or not', and 'performance test of scenarios'.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.717-724
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• 2005

In this paper, we Propose an efficient scheduler well suited for the next-generation wireless networks that can support multimedia traffic having various requirements. The scheduler is designed to provide each of multimedia classes with differentiated services. In particular, the scheduler is intended to maximize throughput and minimize packet loss ratio. To apply the scheduler, we suppose that the wireless network is based on TDD/CDMA system The scheduler assigns a packet in a dedicated uplink-slot to the user within a frame to operate scheduling of packets transmitted by the users belonging to the specific class in an efficient manner. Such a manner also enables the scheduler to meet different QoS requirements. The paper also includes performance comparison with other schemes and analysis of the proposed scheduling algorithm by using simulation. We also analyze the proposed scheme by using simulation. The simulation compares the proposed scheduling algerian with previously proposed schemes in terms of the performance.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.4
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• pp.141-151
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• 2017

Nowadays, It is undeniable that the threat of network security is growing as time flows due to worldwide development of wire/wireless, various Internet platform and sophisticated hacking techniques. The amount of traffics that Network security solution has to handle is increasing and recently many occurrence of explosive traffic attacks from PulseWave are being observed which has many similar characteristics to New DDos. Medium and small sized firms abroad have developed and distributed Snort and Suricata that are based on open-source Intrusion Detection System(IDS) / Intrusion Prevention System (IPS). The goal of this study is to compare between Windows7 by applying suicata 4.0.0 32bit version and Ubuntu 16.04.3 LTS by applying suicata 4.0.0 version which is an open source Intrusion Detection System / Intrusion Protection System that uses multi threads method. This experiment's environment was set as followed C1100 server model of Dell, Intel Xeon CPU L5520 2.27GHz*2 with 8 cores and 16 threads, 72GB of RAM, Samsung SSD 250GB*4 of HDD which was set on RAID0. According to the result, Suricata in Ubuntu is superior to Suricata in Windows7 in performance and this result indicates that Ubuntu's performance is far advanced than Windows7. This meaningful result is derived because Ubuntu that applied Suricata used multi core CPU and RAM more effectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.11
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• pp.2920-2939
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• 2012

Enterprises that develop online games have to deploy supporting infrastructures, including hardware and bandwidth resources, in order to provide a good service to users. First Person Shooter games generate high rates of small UDP packets from the client to the server, so the overhead is significant. This work analyzes a method that saves bandwidth, by the addition of a local agent which queues packets, compresses headers and uses a tunnel to send a number of packets within a multiplexed packet. The behavior of the system has been studied, showing that significant bandwidth savings can be achieved. For certain titles, up to 38% of the bandwidth can be saved for IPv4. This percentage increases to 54% for IPv6, as this protocol has a bigger overhead. The cost of these bandwidth savings is the addition of a new delay, which has an upper bound that can be modified. So there is a tradeoff: the greater the added delays, the greater the bandwidth savings. Significant reductions in the amounts of packets per second generated can also be obtained. Tests have been deployed in an emulated scenario matching an access network, showing that if the number of players is big enough, the added delays can be acceptable in terms of user experience.