• Journal of information and communication convergence engineering
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• v.13 no.1
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• pp.21-26
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• 2015

A wireless sensor network (WSN) is designed and implemented for a freeze dryer. Freeze-drying technology is widely used in the fields of pharmacy and biotechnology as well as the food and agriculture industries. Taking into account the demand for high-resolution pressure and temperature measurements in a freeze dryer, the proposed WSN has a significant advantage of creating a monitoring environment in a freeze dryer. The proposed WSN uses a ZigBee/IEEE 802.15.4 network with an altimeter module that contains a high-resolution pressure and temperature sensor with a serial digital data interface. The ZigBee network is suitable for low-energy and low-data-rate applications in the field of wireless communication. The altimeter module is capable of sensing pressure in the range of 7.5-975 Torr (10-1300 mbar) and temperature in the range of $-40^{\circ}C$ to $125^{\circ}C$ with a DC power consumption of $3{\mu}W$. The implemented WSN is installed in a commercial laboratory freeze dryer in order to demonstrate its functionality and efficiency. A comparison with the temperature profile measured by a thermocouple installed in the freeze dryer reveals that the resolution of the temperature profile measured by WSN is superior to that measured by the thermocouple.

• Journal of the Korea Society of Computer and Information
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• v.19 no.6
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• pp.61-69
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• 2014

Various Time Synchronization protocols considering for the characteristics of WSN(Wireless Sensor Network) have been developed, because a time relationship plays an important role in many WSN applications, as well. Synchronization accuracy as well as constraints of energy should be considered for WSN Time Synchronization protocols, especially. In this paper, I analyze Time Synchronization protocols for WSN after classifying these protocols with a new criteria (i.e. power consumption). So, this method will contribute to evaluating and comparing WSN Time Synchronization protocols in respect of power consumption.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.361-364
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• 2008

The Application Model in Wireless Sensor Networks(WSNs) consist of wireless sensor network based on sensor hardwares which is combined the micro-controller, chipset for wireless communication and sensors, middleware for dealing with data processing and user application for common service. Applications in WSN have been applied for environmental monitoring, smart factory and have concentrated the services based on remote monitoring applications which is difficult to watch the situation by human. In this paper, we described the construction model for applying for the Ubiquitous disaster prevention system and deal with its conformity. The proposed system includes the selecting the wireless sensor hardware, routing technique for u-Disaster Prevention, composition of middleware and web-interface for application services.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.3
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• pp.180-190
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• 2011

Efficient energy consumption is a critical factor for deployment and operation of wireless sensor networks (WSNs). To achieve energy efficiency there have been several hierarchical routing protocols that organize sensors into clusters where one sensor is a cluster-head to forward messages received from its cluster-member sensors to the base station of the WSN. In this paper, we propose a self-organized clustering method for cluster-head selection and cluster based routing for a WSN. To select cluster-heads and organize clustermembers for each cluster, every sensor uses only local information and simple decision mechanisms which are aimed at configuring a self-organized system. By these self-organized interactions among sensors and selforganized selection of cluster-heads, the suggested method can form clusters for a WSN and decide routing paths energy efficiently. We compare our clustering method with a clustering method that is a well known routing protocol for the WSNs. In our computational experiments, we show that the energy consumptions and the lifetimes of our method are better than those of the compared method. The experiments also shows that the suggested method demonstrate properly some self-organized properties such as robustness and adaptability against uncertainty for WSN's.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2185-2191
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• 2007

The traditional sensor network is composed of the cable and the sensor of high price, when collecting a sensing data, there is a weak point which is not pliability. WSN uses the equipment of low price, it will be able to collect the data which is diverse from various node. In this paper we composed coal mining topology which used IEEE802.15.4 MAC in Korea Coal Corporation site. We proposed models for the mobility support of the work manager from the coal mining, we selected the optimum model through simulation experiments. When applying the WSN in the Korea Coal Corporation and other mines, this result can be used as a basis.

• Journal of IKEEE
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• v.23 no.2
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• pp.413-418
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• 2019

Attacks on existing sensor networks include sniffing, flooding, and spoofing attacks. The basic countermeasures include encryption and authentication methods and switching methods. Wormhole attack, HELLO flood attack, Sybil attack, sinkhole attack, and selective delivery attack are the attacks on the network layer in wireless sensor network (WSN). These attacks may not be defended by the basic countmeasures mentioned above. In this paper, new countermeasures against these attacks include periodic key changes and regular network monitoring. Moreover, we present various threats (attacks) in the network layer of wireless sensor networks and new countermeasures accordingly.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.95-97
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• 2019

본 논문에서는 ZigBee 기반의 WSN과 노드 연결을 위한 새로운 기법을 제안한다. 이 기법은 통신 노드 간에 격리된 노드의 수를 최소화하기 위해 수신신호강도(RSSI) 샘플에 적용된 딕슨 테스트(Dixon's test)를 사용하여 ZigBee 기반의 WSN을 위한 새로운 노드 연결 구조로써 특이점(outlier)을 제거하여 적은 수의 RSSI 값으로도 정확한 노드 연결이 가능하다. 본 논문에서는 시뮬레이션을 통하여 제안하는 기법이 기존의 RSSI 기반의 기법보다 더 높은 정확도를 유지하면서 처리 시간은 줄어든 것을 증명하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.103-104
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• 2019

본 논문에서는 무선 센서 네트워크(Wireless Sensor Network, WSN) 환경에 배치되어 있는 각 센서들의 데이터 수집을 위한 싱크(Sink)가 일정 주기로 재배치되는 싱크 마이그레이션(Migration) 과정에서 센서 데이터를 종합하여 싱크로 전송하는 클러스터 헤드(Cluster Head, CH)의 자원 효율성 증대를 위해 중간 경로를 활용한 센서 할당 기법을 제안한다. 본 논문에서는 WSN 환경을 바탕으로 해당 기법을 적용하여 싱크 재배치 과정을 시뮬레이션 하였으며, 해당 실험의 결과에 따르면 클러스터 헤드의 자원 효율성 및 전체 센서 데이터의 수집률이 향상되었다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.2047-2051
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• 2009

In this paper, we propose the localization method on WSN(Wireless Sensor Network) using fuzzy model and Kalman filter. The proposed method is as follows: First, we estimate the distance of RSSI(Receive Signal Strength Index) by using fuzzy model in order to minimize the distance error. Second, we use a triangulation measurement for estimating the localization. And then, we minimize the localization error using a Kalman filter. Finally, we show the effectiveness and feasibility of the proposed method through some experiments.

• Information and Communications Magazine
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• v.25 no.10
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• pp.33-41
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• 2008

21세기의 사회적, 환경적 변화의 의미뿐만 아니라 기술 발전의 방향까지도 포함하는 유비쿼터스 사회의 핵심 기술 중에 한 가지는 WSN (Wireless Sensor Network) 기술이라 할 수 있다. 본고에서는 WSN과 관련된 핵심 칩 셋 및 소프트웨어의 관련 기술동향을 살펴보고 국외의 재난 방재 및 생태모니터링뿐만 아니라, 헬스케어 등의 응용사례를 살펴본다.