• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.13-28
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• 2009

Routing protocols in Delay/Disruption Tolerant Networks(DTN) are important to enhance the performance of transmission delay and delivery success ratio. In this paper, we propose an efficient DTN routing algorithm, called "Nobility Pattern based Routing(MPR)", that controls the total number of transferred message copies based on mobility patterns of mobile nodes. We consider a realistic "Levy walk" mobility pattern that has a super-diffusive property which well represents human mobility pattern. We implemented a DTN simulator using ONE simulator for the proposed MPR algorithm and Levy walk mobility pattern. Simulation results show that mobility patterns are very important for accurate evaluation of DTN routing performance, and the proposed MPR enhances the routing performance of delivery delay and success delivery ratio under realistic mobility pattern.

• Convergence Security Journal
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• v.11 no.6
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• pp.25-30
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• 2011

MANET has a weak construction in security more because it is consisted of only moving nodes and doesn't have central management system. The DDoS attack is a serious attack among these attacks which threaten wireless network. The DDoS attack has various object and trick and become intelligent. In this paper, we propose the technique to raise DDoS detection rate by classifying abnormal traffic pattern. Cluster head performs sentinel agent after nodes which compose MANET are made into cluster. The decision tree is applied to detect abnormal traffic pattern after the sentinel agent collects all traffics and it judges traffic pattern and detects attack also. We confirm high attack detection rate of proposed detection technique in this study through experimentation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.90-92
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• 2017

Due to the popularity of social networks and the development of technology in mobile networking, the mobile social networks (MSNs) provide opportunities for the spread of information between mobile devices. As a result, understanding the information diffusion in the emerging MSNs is a critical issue. Many research studies have addressed diffusion minimization, which is a problem of how to find the proper initial k users who can effectively propagate as widely as possible in the minimum amount of time, similar to influence maximization. We address a study on association analysis among nodes in information diffusion and mobility pattern for mobile social networks. Experiments in our study were conducted in the Opportunistic Network Environment (ONE) simulator using GPS trace of mobile node, to show that the study results in MSNs. We also demonstrate that our experiments outperform other existing algorithms with various communication range and ratio of k influential nodes.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1207-1210
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• 2005

본 논문에서는 센서 네트워크에서 수명을 연장하기 위해 이동하는 모바일 싱크를 사용할 때 싱크가 이동함에 따라 늘어난 전체 네트워크 트래픽 량을 줄여 더욱더 수명을 연장하기 위해서 클러스터를 도입한다. 고정된 위치에서 싱크가 데이터를 수집할 경우 싱크 한 홉 내에 있는 노드들이 에너지를 빨리 소모하여 네트워크 파티션이 일어나기 쉽기 때문에 모바일 싱크를 사용하여 네트워크 수명을 연장하는 방법이 연구되었다. 이에 우리는 모바일 싱크가 이동하는 패턴이 주어지고 센서들로부터 매 T 마다 데이터를 받는다고 할 때 모바일 싱크와 클러스터를 함께 사용하였을 경우 네트워크 성능을 분석하고 에너지 효율적인 클러스터 형성 방법에 대해서 제안한다.

• Journal of Korea Multimedia Society
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• v.10 no.4
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• pp.548-558
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• 2007

This paper presents a method of location sensing of mobile objects using RF devices. By analyzing signal strengths between a certain number of fixed RF devices and a moving RF device, we can recognize the location of a moving object in real time. Firstly, signal strength values between RF devices are gathered, and then the values are normalized and constructed as a model feature vector for specific location. A number of model patterns are acquired and registered for all of the location which we want to recognize. For location sensing, signal strength information for an arbitrary moving RF device is acquired and compared with model feature vectors registered previously. In this case, distance value is calculated and the moving RF device is classified as one of the known model patterns. Experimental results show that our methods have performed the location sensing successfully with 100% rate of recognition when the number of fixed RF devices is 10 or more than 12. In terms of cost and applicability, experimental results seem to be very encouraging.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.40-45
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• 2015

In this paper, we proposed and implemented a crime prediction algorithm based upon crime influential factors. To collect the crime-related big data, we used a data which had been collected and was published in the supreme prosecutors' office. The algorithm analyzed various crime patterns in Seoul from 2011 to 2013 using the spatial statistics analysis. Also, for the crime prediction algorithm, we adopted a Bayesian network. The Bayesian network consist of various spatial, populational and social characteristics. In addition, for the more precise prediction, we also considered date, time, and weather factors. As the result of the proposed algorithm, we could figure out the different crime patterns in Seoul, and confirmed the prediction accuracy of the proposed algorithm.

• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.11-12
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• 2013

최근 대규모 데이터의 처리와 관리를 위한 분산 저장 및 처리 시스템의 연구 및 활용이 중요해지고 있다. 대표적인 분산 저장 및 처리시스템으로써 하둡(Hadoop)이 널리 활용되고 있다. 하둡 분산 파일 시스템을 기반으로 수행되는 맵-리듀스에서 테스크 할당은 데이터의 로컬리티를 고려하여 최대한 가깝게 할당한다. 하지만 맵-리듀스에서의 데이터 분석 작업에서 작업 형태에 따라 빈번하게 요청되는 데이터가 존재한다. 이러한 경우, 해당 데이터의 낮은 로컬리티로 인해 수행시간 증가 및 데이터 전송의 지연의 문제점을 야기 시킨다. 본 논문에서는 맵-리듀스의 처리 속도 향상을 위한 데이터 접근 패턴에 따른 핫-데이터 복제 기법을 제안한다. 제안하는 기법에서는 데이터 접근 패턴에 따라 높은 접근 빈도를 보이는 핫-데이터에 대한 복제본 최적화 알고리즘을 활용하여 데이터 로컬리티를 향상시키고 결과적으로 작업 수행시간을 감소시킨다. 제안하는 기법은 기존 기법에 비해 모든 노드의 데이터 이동이 감소하여 접근빈도의 분포가 균형적인 것을 확인하였다. 성능평가 결과, 기존 기법에 비해 접근 빈도의 부하가 약 8% 감소하는 것을 확인하였다.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.345-354
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• 2008

Recently, small-scale mobile network which is composed of many mobile devices in a man becomes popular. Also, Examples of large-scale mobile network can be thought access networks deployed on public transportation such as ships, trains and buses. To provide seamless mobility for mobile nodes in this mobile network, binding update messages must be exchanged frequently. However, it incurs network overhead increasingly and decreases energy efficiency of mobile router. If we try to reduce the number of the messages to cope with the problem, it may happen the security -related problems conversely Thus, mobile router needs a effective algorithm to update location information with low cost and to cover security problems. In this paper, mobility management scheme based on mobile router's mobility pattern is proposed. Whenever each mobile router leaves a visiting network, it records related information as moving log. And then it periodically computes mean resident time for all visited network, and saves them in the profile. If each mobile router moves into the visited network hereafter, the number of binding update messages can be reduced since current resident time may be expected based on the profile. At this time, of course, security problems can happen. The problems, however, are solved using key credit, which just sends some keys once. Through extensive experiments, bandwidth usages are measured to compare binding update messages in proposed scheme with that in existing scheme. From the results, we can reduce about 65% of mobility-management-related messages especially when mobile router stays more than 50 minutes in a network. Namely, the proposed scheme improves network usage and energy usage of mobile router by decreasing the number of messages and authorization procedure.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.4
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• pp.105-111
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• 2010

This paper proposes the recursive algorithm for passive proximity detection system based on signal strength. The system is designed to be used in the smart medicine chest in order to provide location-based service for the senior personnel. Due to the system profile, single receiver and uni-direction communication are applied over the signal attenuation model for the determination of user existence within certain proximity. The performance of conventional methods is subjective to the sight between the transmitter and receiver unless the direction of target is known. To appreciate the temporal and spatial locality of human subjects, the authors present exponential moving average (EMA) to compensate the unexpected position error from the direction and/or environment. By using optimal parameter, the experiments with EMA algorithm demonstrates 32.26% (maximum 40.80%) reduction in average of the error probability with 50% of consecutive sight in time.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.26-33
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• 2011

In ubiquitous environments that numerous mobile objects exist, the location-based services have risen as an important application field. For efficient location-based services, various techniques with broadcast schemes have been studied. However, they were mainly concerned with the implementation of a broadcast index and did not consider techniques for reducing the size of the entire broadcast data. Therefore, this paper proposes a data distribution broadcast scheme based on sensor networks that considers the mobile patterns of an object in road network environments. In this paper we also propose a road network based sensor clustering technique for the efficiency of the proposed distributed broadcast scheme. In order to show the superiority of the proposed scheme, we compare it with the existing broadcast scheme in various environments.