• The KIPS Transactions:PartC
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• v.16C no.5
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• pp.615-620
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• 2009

Nowadays, wireless infrastructures such as sensor networks are widely used in many different areas. In case of sensor networks, the wirelessly connected sensors can execute different kind of tasks in a diversity of environments, and one of the most important parameter for a successful execution of such tasks is the location information of each node. As to localization problems in WSNs, there are ToA (Timer of Arrival), RSS (Received Signal Strength), AoA (Angle of Arrival), etc. In this paper, we propose a modification of existing ToA and RSS based methods, adding a weighted average scheme to measure more precisely the distance between nodes. The comparison experiments with the traditional ToA method show that the average error value of proposed method is reduced by 0.1 cm in indoor environment ($5m{\times}7m$) and 0.6cm in outdoor environment ($10{\times}10m$).

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1207-1210
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• 2008

무선 센서 네트워크는 고정 인프라 없이 센서 노드만으로 정보를 수집하는 네트워크로서 센서들의 위치정보 식별은 매우 중요하다. 센서 노드간 거리 측정은 신호의 도착시간차(Time of Arrival: ToA), 신호세기(Received Signal Strength: RSS), 신호각도(Angle of Arrival: AoA)에 기반을 둔 방법 등이 있다. 무선 센서 네트워크에 배치되어 있는 각 센서 노드간 정확한 거리 식별을 위해 기존의 거리 측정 방법을 보완하여 거리 오차를 줄이는 ToA기반의 RSS보정 방법을 제안한다. 구체적으로 초음파를 통한 거리측정 값에 맵(RF-MAP)을 통해 보정한 RSS값을 가중치로 보정하여 기존의 거리 측정 방법보다 측정오차를 줄였다. 실험을 통해 제안한 방법은 기존 ToA보다 실내(5m×7m)에서 평균 0.1cm, 실외(10m×10m) 평균 0.6cm 측정 오차를 줄일 수 있음을 확인 할 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1491-1497
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• 2009

Existing methods to measure are based on ToA (Timer of Arrival), RSS (Received Signal Strength), AoA(Angle of Arrival) and other methods. In this paper, we propose a compensation of ToA and RSS methods to measure more precisely the distance of nodes. The comparison experiments with the traditional ToA method show that the average error value of proposed method is reduced 30%. We believe that this proposal can improve location estimation of sensor nodes in wireless sensor networks.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.151-159
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• 2008

Mobile broadband wireless network is emerging as one of the hottest research areas due to technical advances, and the demands of users who wish to enjoy the same network experience on the move. In this paper, we investigate the handover process at the medium access control (MAC) layer in an IEEE 802.16e-based system. In particular, we identify problems concerned with the scan initiation Process called cell reselection and propose a received signal strength (RSS) estimation scheme to dynamically trigger a scanning process. We show how the RSS estimation scheme can timely initiate a scanning process by anticipating RSS values considering scan duration required.

• Journal of Internet Computing and Services
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• v.12 no.5
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• pp.113-125
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• 2011

As information resources have become more various and the number of the resources has increased, knowledge customization on the social web has been becoming more difficult. To reduce the burden, we offer a framework for context-based similarity calculation for knowledge customization using ontology on the CBR. Thereby, we newly developed context- and intensity-based similarity calculation methods which are applied to extraction of the most similar case considered semantic similarity and syntactic, and effective creation of the user-tailored knowledge using the selected case. The process is comprised of conversion of unstructured web information into cases, extraction of an appropriate case according to the user requirements, and customization of the knowledge using the selected case. In the experimental section, the effectiveness of the developed similarity methods are compared with other edge-counting similarity methods using two classes which are compared with each other. It shows that our framework leads higher similarity values for conceptually close classes compared with other methods.