• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.25-31
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• 2016

Recently, with greatly improving the wireless communication technology, new services are created using smart sensors, i.e., machine-to-machine (M2M) and Internet of Things (IoT). In this paper, we propose a novel IoT device (IoTD) personalization method that adopt Small-cell Access Points (SAPs) to control IoTDs using user equipments (UEs), e.g., smart phones and tablet PC, from service users. First, we introduce a system architecture that consists of UE, IoTD, and SAP and propose the IoTD personalization method with two procedures, i.e., IoTD profile registration procedure and IoTD control procedure. Finally, through simulations, we evaluated the system performance of the proposed scheme and it is shown that the proposed scheme outperforms the conventional scheme in terms of the packet delay, packet loss probability, and normalized throughput.

• Journal of Korea Multimedia Society
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• v.17 no.8
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• pp.1020-1024
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• 2014

The environment information such as dust, temperature, humidity, illumination and gas are very important in daily life. We implemented multi-sensor system which made for measuring an environment by using Arduino, ZigBee, and Appinventor. We also designed a packet for transmitting environment data. The data are sent to the server via ZigBee and then it communicates to a smart phone via WI-Fi. In this study, we added divers sensors, designed a protocol which made for transfer several kinds of data and improve mobility for real time monitoring by using smart phones. The system was worked well and the data was transmitted correctly to the smart phone.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.447-450
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• 2011

행정기관 VoIP 서비스는 현재 PSTN망과 인터넷망을 활용하여 기존 전화망보다 저렴한 가격에 음성통화를 할 수 있게 해주는 서비스로 확대되고 있다. 하지만 공공의 보안이 유지 되어야 할 행정기관 VoIP의 경우 보안취약성에 대한 문제들이 발생하고, 해커의 공격을 받을 가능성이 높다. 본 논문은 행정기관에서 유 무선 인터넷을 이용하여 VoIP 서비스 이용 시 발생할 수 있는 침해사고 유형을 분석하고 도청 공격을 실시하여 취약점을 분석한다. 행정기관용 Smart Phone으로 VoIP 취약점을 분석을 위하여 OmniPeek와 AirPcap 장비가 설치되어 있는 실험실 환경에서 도청 공격을 실시한 다. 도청 공격에 따르는 Packet을 분석하고, IP을 확인하여 공격에 의한 침해사고로 도청이 이루어짐을 시험으로 증명한다. 본 논문의 연구는 행정기관뿐 아니라 일반사용자의 Smart Phone과 VoIP 서비스 보안성 강화에 기초자료로 제공 될 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3100-3116
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• 2016

With the rapid development of urban traffic system and fast increasing of vehicle numbers, the traditional centralized ways to generate the source-destination shortest path in terms of travel time(the optimal path) encounter several problems, such as high server pressure, low query efficiency, roads state without in-time updating. With the widespread use of smart cameras in the urban traffic and surveillance system, this paper maps the optimal path finding problem in the dynamic road network to the shortest routing problem in the smart camera networks. The proposed distributed optimal path generation algorithm employs the delay routing and caching mechanism. Real-time route update is also presented to adapt to the dynamic road network. The test result shows that this algorithm has advantages in both query time and query packet numbers.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.1
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• pp.147-156
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• 2017

This paper analyzes the performance limit of WAVE system for the platooning service requirements which is referred from the de facto standards. The performance of the packet error rate and mean delay as key parameters in the wireless communication systems should be satisfied to provide safety to the platooning vehicles. The test scenarios are conducted by considering the following vehicle groups: platooning vehicles, vehicles within a hop distance and vehicles within two hop distance( called hidden node vehicles). The models of packet error rate and delay deals with the topology of aforementioned vehicle groups, vehicle speed and communication range. The numerical results are obtained in terms of packet size, packet arrival rate and data transmission rate. Finally, this paper suggests the robust range of packet error rate and delay for the WAVE system to provide the platooning vehicle service.

• Smart Structures and Systems
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• v.11 no.6
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• pp.589-604
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• 2013

Identification of damage has become an evolving area of research over the last few decades with increasing the need of online health monitoring of the large structures. The visual damage detection can be impractical, expensive and ineffective in case of large structures, e.g., offshore platforms, offshore pipelines, multi-storied buildings and bridges. Damage in a system causes a change in the dynamic properties of the system. The structural damage is typically a local phenomenon, which tends to be captured by higher frequency signals. Most of vibration-based damage detection methods require modal properties that are obtained from measured signals through the system identification techniques. However, the modal properties such as natural frequencies and mode shapes are not such good sensitive indication of structural damage. Identification of damaged jacket type offshore platform members, based on wavelet packet transform is presented in this paper. The jacket platform is excited by simple wave load. Response of actual jacket needs to be measured. Dynamic signals are measured by finite element analysis result. It is assumed that this is actual response of the platform measured in the field. The dynamic signals first decomposed into wavelet packet components. Then eliminating some of the component signals (eliminate approximation component of wavelet packet decomposition), component energies of remained signal (detail components) are calculated and used for damage assessment. This method is called Detail Signal Energy Rate Index (DSERI). The results show that reduced wavelet packet component energies are good candidate indices which are sensitive to structural damage. These component energies can be used for damage assessment including identifying damage occurrence and are applicable for finding damages' location.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1711-1717
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• 2014

There have been many studies on IEEE 802.15.4 for home area networks(HAN) in Smart Grids. Existing unslotted or slotted IEEE 802.15.4 has almost not met strict conditions of the U.S. Department Of Energy(DOE). This study proposed a improved algorithm that reduces collisions, delay time and changes in the delay time. For this purpose, numbers were given to nodes to make the transmission in the order of the node numbers. Since the probability of the occurrence of collisions would decrease compared to random transmission if the nodes were given numbers, Backoff time was set at 0. In the proposed Numbered-Unslotted-ZeroBackoff algorithm, when the packet size was 133 octets and less than 180 packets per second occurred, it was found that packet delivery ratio was over 99.99%, and that all the maximum delay, the mean delay and the minimum delay were less than 0.02 seconds. This paper could confirm that the algorithm proposed in this study met the strict conditions of the DOE.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.3
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• pp.169-177
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• 2016

To realize high-speed intrusion detection by accommodating many regular expression (regex)-based signatures and growing network link capacities, we propose the Service TimE-Aware Load-balancing (STEAL) algorithm. This work is motivated from the observation that utilization of a many-core network intrusion detection system (NIDS) is influenced by unfair computational distribution among many-core NIDS nodes. To avoid such unfair computational distribution, STEAL is designed to dynamically distribute a large volume of traffic among many-core NIDS nodes based on packet service time, which is represented by the deep packet time in many-core NIDS nodes. From experiments, we show that compared to the commonly used load-balancing algorithm based on arrival rate, STEAL increases the number of received packets (i.e., decreases the number of dropped packets) in many-core NIDS. Specifically, by integrating an open source NIDS (i.e. Bro) with STEAL, we show that even under attack-dominant traffic and with many signatures, STEAL can rapidly improve the performance of many-core NIDS to realize high-speed intrusion detection.

• The Journal of the Korea Contents Association
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• v.19 no.12
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• pp.407-415
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• 2019

As the IT environment changes with cloud computing and smart work, the existing perimeter security model is showing its limitations and Software Defined Perimeter is being discussed as an alternative. However, SDP Spec 1.0 does not specify the device registration procedure, policy distribution process and authentication key generation and sharing process.In this paper, we propose a method to solve the problem of SDP access control by improving the operation procedure of Single Packet Authentication. This paper suggests that the proposed method can implement a consistent and automated integrated access control policy compared to the existing access control methods.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.3
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• pp.148-159
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• 2013

An analysis of the throughput and stability region of random access systems is currently of interest in research and industry. This study evaluated the performance of a multiuser random access channel with a retransmission gain. The channel was composed of a media access control (MAC) determined by the transmission probabilities and a multiuser communication channel characterized by the packet reception probabilities as functions of the number of packet transmissions and the collision status. The analysis began with an illustrative two-user channel, and was extended to a general multiuser channel. For the two-user channel, a sufficient condition was derived, under which the maximum throughput was achieved with a control-free MAC. For the channel with retransmission gain, the maximum steady throughput was obtained in a closed form. The condition under which the random access channel can acquire retransmission gain was also obtained. The stability region of the general random access channel was derived. These results include those of the well-known orthogonal channel, collision channel and slotted Aloha channel with packet reception as a special instance. The analytical and numerical results showed that exploiting the retransmission gain can increase the throughput significantly and expand the stability region of the random access channel. The analytical results predicted the performance in the simulations quite well.