• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.379-384
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• 2012

This paper presents the power source of wireless sensor node (WSN) using supercapacitors and a solar cell. Supercapacitors have high lifetime cycling compared to that of batteries. Supercapacitors are connected in series to achieve higher voltage and a voltage balancing circuit is required to ensure that no individual cell goes overvoltage. We employ an active balancing circuit that draws minimal current by using transistors. A diode is connected in series with each supercapacitor. A new balancing circuit that equalize the cells-voltage reduces energy consumption of supercapacitors. Voltage of operating WSN is applied 2.2-3.3V by DC/DC converter and supercapacitor voltage 2.2-5.1V. Maximum operating time of wireless sensor node is about 16 hours in full charging.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.4
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• pp.1090-1105
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• 2012

A multi-modal sensing M2M healthcare monitoring system for the continuous monitoring of patients under their natural physiological states or elderly persons with chronic diseases is summarized. The system is designed for homecare or the monitoring of the elderly who live in country side or small rest home without enough support from caregivers or doctors, instead of patient monitoring in big hospital environment. Further insights into the natural cause and progression of diseases are afforded by context-aware sensing, which includes the use of accelerometers to monitor patient activities, or by location-aware indoor tracking based on ultrasonic and RF sensing. Moreover, indoor location tracking provides information about the location of patients in their physical environment and helps the caregiver in the provision of appropriate support.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.544-550
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• 2008

In this paper, an efficient positioning algorithm is proposed for a local positioning system using ultrasound and RF in WSN. The proposed positioning algorithm is the modified Savarese method where measurement noise characteristics are included as a weighting. Furthermore the ill-conditioned and the singularity problem occurred when all beacons are installed at the same height are removed. And the method is applicable to 2D positioning with 2 beacons only. The experiments with implemented system show the accurate seamless positioning less than 2cm error both static and dynamic experiments while the original Savarese method can not provide positions.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.998-1007
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• 2018

The advent of Wireless Sensor Networks (WSN) has led to their use in numerous applications. Sensors are autonomous in nature and are constrained by limited resources. Designing an autonomous topology with criteria for economic and energy conservation is considered a major goal in WSN. The proposed honey-hive clustering consumes minimum energy and resources with minimal transmission delay compared to the existing approaches. The honey-hive approach consists of two phases. The first phase is an Intra-Cluster Min-Max Discrepancy (ICMMD) analysis, which is based on the local honey-hive data gathering technique and the second phase is Inter-Cluster Frequency Matching (ICFM), which is based on the global optimal data aggregation. The proposed data aggregation mechanism increases the optimal connectivity range of the sensor node to a considerable degree for inter-cluster and intra-cluster coverage with an improved optimal energy conservation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.331-333
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• 2010

최근 IT산업의 발전으로 인해 광범위한 정보가 존재하는 웹 기반 환경에서 원하는 정보의 검색과 검출을 위한 시멘틱 웹(Semantic Web) 기반의 온톨리지에 대하여 연구가 다양하게 진행 중이다. 본 논문에서는 온톨로지 기법을 이용하여 인간의 다양한 편의와 친환경적인 습지의 수질 관리에 대한 통합적이고 편리한 관리를 위해 WSN 기반의 습지 수질 관리에 특화된 온톨리지 설계 및 구축을 진행하였다.

• The Korean Journal of Food And Nutrition
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• v.9 no.2
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• pp.143-150
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• 1996

The studies was carried out to investigate ripening degree and functional properties of EMC produced with pancreatic protease and palatase ML. During production of EMC, the amounts of free amino acid and free fatty acid were increased with increasing the reaction time. The amount of total nitrogen(T-N) and water soluble nitrogen(WSN) were increased with increasing time. EMC had contents of 1.79eA T-N and 0.52o WSN at 60 min of hydrolysis time. SRI and FRI value had also a similar correlationship. On the gel filtration, 2 kinds of soluble proteining capacity was also shown in alkali solution. Furthermore the foaming stability had the same result as that of the solubility. The water absorption of EMC showed the highest level at pH 4.0 and 5.0.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.53-54
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• 2006

In this paper, we analytically evaluate packet delay and energy consumption of S-MAC protocol with a modified Markov chain model. Although some models, based on IEEE 802.11 MAC protocol, to analyze the S-MAC protocol in wireless sensor network (WSN) have been proposed, they fail to consider the differences in architecture between the S-MAC and the 802.11 MAC. Therefore, by reflecting the significant features in the S-MAC function, we model the operation of S-MAC protocol, and derive its packet delay and energy consumption in single-hop WSN. Numerical results show the delay and the dissipated energy at various duty cycle values according to offered load, where a practical mote is used.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.725-730
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• 2012

In this paper, we propose the localization algorithm for the cooperative behavior of the swarm robots based on WSN (Wireless Sensor Network). The proposed method is as follows: First, we measure positions of the L-bot (Leader robot) and F-bots (Follower robots) by using the APIT (Approximate Point In Triangle) and the RSSI (Received Signal Strength Indication). Second, we measure relative positions of the F-bots against the pre-measured position of the L-bot by using trilateration. Then, to revise a position error caused by noise of the wireless signal, we use the particle filter. Finally, we show the effectiveness and feasibility of the proposed method though some simulations.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.35-36
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• 2007

본 논문은 beacon을 기준으로 등기화된 노드들 간의 데이터 전송을 위한 프로토콜로써 실시간성과 낮은 전력 소모를 보장하고 있다 이 프로토콜은 노드가 주위 센서 노드로부터의 데이터를 모아서 계단 형태로 부모 노드에게 동기화 되어 전송하는 Sync-Stair 센서 네트워크 프로토콜이며, 기본적으로 TDMA를 기반으로 동기화되며 데이터 전송을 위해 CSMA-CA를 사용한다. Sync-Stair 네트워크는 Branch 노드와 Sensor 노드의 2 종류의 디바이스 타입이 존재한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.71-72
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• 2015

WSN의 센서 노드는 제한된 자원으로 인해 보안상의 취약성을 가지며 공격자는 쉽게 임의의 데이터를 삽입하는 허위 데이터 주입 공격을 할 수 있다. WSN에서는 이러한 공격이 치명적이기 때문에 허위 데이터를 가능한 빨리 여과해야 한다. 허위 데이터 주입 공격을 탐지하는 기법으로 동적 여과 기법이 제안되었는데 이 기법은 초기 분배된 비밀키에 대한 재분배가 이루어지지 않아 같은 공격에 계속 노출될 경우 불필요한 에너지 소모가 발생한다. 본 논문에서 제안하는 기법은 효율적인 키 재분배를 통해 허위 데이터를 빨리 감지하고 에너지 효율성을 향상시킨다. 전달 노드에서 허위 데이터가 탐지되면 정의된 알람 메시지를 통해 베이스 스테이션에 보고되고 키 재분배를 수행하여 더 효율적으로 허위 데이터를 감지한다. 그러므로 제안 기법은 기존 기법과 비교하였을 때 허위 데이터를 조기에 감지하고 전체 네트워크의 에너지를 절약한다.