• Annual Conference of KIPS
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• 2010.11a
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• pp.1297-1299
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• 2010

무선 통신에서는 무선 통신의 브로드캐스트한 특성으로 데이터의 기밀성 유지를 위한 암호화가 매우 중요하다. 특히 무선 센서 네트워크(WSN - Wireless Sensor Network)의 경우 일반적인 PC와는 다르게 다양한 환경에 위치할 수 있어 공격자에게 더 쉽게 노출 될 수 있는 문제점을 가지고 있다. 이런 환경에서 미리 저장된 해쉬 함수나 비밀 값에 의존한 키 분배를 할 경우 저장된 값이 노출될 경우 심각한 문제를 초래하게 된다. 그리고 D-H 키 분배 알고리즘의 경우 키 값을 안전하게 도출을 할 수 있지만 키를 도출한 대상에 대한 인증의 부재와 멀티 홉 환경에서 중간자 공격에 취약한 문제점을 드러내고 있다. 본 논문에서는 이런 문제를 해결하기위해 기존 연구를 응용하여 멀티 홉 환경에서 무선 통신의 특성을 이용한 비밀값 공유와 제 3의 노드를 이용한 간단한 인증이 가능한 기법을 제안한다.

• Annual Conference of KIPS
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• 2010.04a
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• pp.251-254
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• 2010

현대사회의 전자와 물리공간의 융합인 유비쿼터스가 진행되고 있다. 이 유비쿼터스 사회가 가능하려면 모든 사물에 컴퓨터 칩인 RFID태그가 부착되어야 한다. RFID는 무선을 통하여 사물의 ID정보를 제공하며, 향후 주변의 상황정보(온도, 습도, 오염정보, 균열정보 등)까지 탐지하여 이를 실시간으로 네트워크에 연결하여 정보를 관리하는 것이다. 앞으로 이 RFID가 가정에서 모든 기기에 부착되어. 시스템화가 된다면 유비쿼터스 가정이 된다. 본 논문에서는 유비쿼터스 사회의 기술적 정의와 자동화 된 지역내 환경제어를 위한 네트웍크를 구현하기 위한 RFID/USN에 대하여 연구하였다.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.1
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• pp.9-16
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• 2023

Robots are expected to expand their scope of application to the military field and take on important missions such as surveillance and enemy detection in the coming future warfare. Swarm robots can perform tasks that are difficult or time-consuming for a single robot to be performed more efficiently due to the advantage of having multiple robots. Swarm robots require mutual recognition and collaboration. So they send and receive vast amounts of data, making it increasingly difficult to verify SW. Hardware-in-the-loop simulation used to increase the reliability of mission verification enables SW verification of complex swarm robots, but the amount of verification data exchanged between the HILS device and the simulator increases exponentially according to the number of systems to be verified. So communication overload may occur. In this paper, we propose a digital twin-based communication optimization technique to solve the communication overload problem that occurs in mission verification of swarm robots. Under the proposed Digital Twin based Multi HILS Framework, Network DT can efficiently allocate network resources to each robot according to the mission scenario through the Network Controller algorithm, and can satisfy all sensor generation rates required by individual robots participating in the group. In addition, as a result of an experiment on packet loss rate, it was possible to reduce the packet loss rate from 15.7% to 0.2%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.55-61
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• 2008

In this paper, we proposed a multi-agent based healthcare system (MAHS) which is the combination of medical sensor module and wireless communication technology. This MAHS provides wide services to mobile telemedicine, patient monitoring, emergency management, doctor's diagnosis and prescription, patients and doctors, information exchange between hospital workers in a long distance. Also, MAHS is connected to Body Area Network (BAN) and a doctor and hospital workers. In addition, we designed and implemented extended JADE based MAHS that reduces hospital server's burden. Agents gather, integrate, and deliver the collected patient's information from sensor, and provide presentation in healthcare environment. Proposed MAHS has advantage that can handle urgent situation in the far away area from hospital like Islands through PDA and mobile device. In addition, by monitoring condition of patient (old man) in a real time base, it shortens time and expense and supports medical service efficiently.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2815-2822
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• 2011

Clustering method in wireless sensor networks is the technique that forms the cluster to aggregate the data and transmit them at the same time that they can use the energy efficiently. In this paper, I propose the hierarchical unequal clustering method using cluster group model. This divides the entire network into two layers. The data aggregated from layer 2 consisted of cluster group is sent to layer 1, after re-aggregation the total data is sent to base station. This method decreases whole energy consumption by using cluster group model with multi-hop communication architecture. Hot spot problem can be solved by establishing unequal cluster. I also show that proposed hierarchical unequal clustering method is better than previous clustering method at the point of network energy efficiency.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.243-248
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• 2013

With rapid growth and fast diffusion of smartphone technologies, many users are deeply concerned about the smart applications and many mobile applications converged with various related technologies are rapidly disseminated. Especially, the convergence technologies like mobile apps that can establish the wireless ad hoc network between smartphone and other peripherals and exchange data are appear and progressed continuously. In this paper, we design and implement the smart app using bluetooth based wireless ad hoc sensor network that can connect smartphone with sensors and exchange data for various smart applications. The proposed smart application in this paper collects data obtained from more than 2 multi-sensors in real time and fulfills the decision making function by storing data at the database and analysing it. The smart application designed and implemented in this paper is the healthcare application that can analyze and evaluate the patient's health condition with sensing data from multi-sensors in real time through bluetooth module.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.10
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• pp.876-884
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• 2012

This paper introduces two multi-hop delay factors which can be caused by conventional TDMA scheduling; queueing delay and delay by random link scheduling, and proposes a new sequential scheduling scheme to resolve these two factors. We also simulate the TDMA network with the proposed link scheduling scheme and compare it with conventional(random) link scheduling scheme in terms of end-to-end packet transmission delay. From the simulation results, the more the average hop distance increases, the more the difference of the delay performance of both scheduling schemes increases. When the average number of hops is 2.66, 4.1, 4.75, and 6.3, the proposed sequential scheduling scheme reduces the average end-to-end delay by about 22%, 36%, 48%, and 55% respectively when compared to the random scheduling scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5276-5298
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• 2019

Internet of Things (IoT) based sensor networks have gained unprecedented popularity in recent years. With the exponential explosion of the objects (sensors and mobiles), the bandwidth and the speed of data transmission are dwarfed by the anticipated emergence of IoT. In this paper, we propose a novel heterogeneous IoT model integrated the power line communication (PLC) and WiFi network to increase the network capacity and cope with the rapid growth of the objects. We firstly propose the mean transmission delay calculation algorithm based the 3D Markov chain according to the multi-priority of the objects. Then, the attractor selection algorithm, which is based on the adaptive behavior of the biological system, is exploited. The combined the 3D Markov chain and the attractor selection model, named MASM, can select the optimal path adaptively in the heterogeneous IoT according to the environment. Furthermore, we verify that the MASM improves the transmission efficiency and reduce the transmission delay effectively. The simulation results show that the MASM is stable to changes in the environment and more applicable for the heterogeneous IoT, compared with the other algorithms.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.153-158
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• 2008

The technology of Software Defined Radio (SDR) is a possible solution to interwork flexibly between various wireless transport protocols. Ubiquitous network, like u-health service network, includes sensor devices or nodes which do not facilitate all the same transport protocols to access network. As such this may be in such unreachable situations as poverty of all required AP (Access Point)’s, faults or contention in a path of particular protocol communication, etc. This paper presents research results of modeling and simulation to analyze transport performance of multi-protocol ubiquitous network which includes SDR-based interwork nodes and congestion-controlled AP’s. Focusing mainly on dynamics of overall transport performance rather than protocol execution procedures, this paper employs the Zeigler’s DEVS (Discrete Event Systems Specification) methodology and DEVSim++simulation environment to experiment.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.11
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• pp.1086-1090
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• 2010

In recent, as many applications of sensor networks increase, various techniques have been studied to efficiently operate network systems. The query optimization scheme that is one of such techniques has been studied to reduce the data transmission cost. The data transmission is of great importance to the energy consumption of sensor networks. In this paper, we propose an energy-efficient multiple queries processing scheme by sharing sensor readings for multiple queries, when they are occurred in sensor networks. The proposed scheme reduces unnecessary data transmissions among the sensor nodes by intuitively identifying their locations using the grid structure. It also efficiently shares the data by recognizing the redundant regions of sensor nodes. In order to show the superiority of the proposed scheme, we compare it with the existing scheme in various experiments. As the result, the proposed scheme reduces about 65% energy consumption over the existing scheme.