• Journal of Korea Multimedia Society
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• v.12 no.10
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• pp.1436-1449
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• 2009

The value of sensing information is decided according to positions of sensor nodes, which are very important in sensor networks. In this paper, we propose a method that estimates positions of nodes by using adjacent node information and received signal strength in a sensor network. With the proposed method, we can find positions of nodes easily because we use information that nodes have. Moreover, we can find distribution easily for all the nodes because we can measure a relative position for a node whose position is not known based on anchor nodes whose positions are already known. We utilized Use case diagram, activity diagram and State machine diagram among several diagrams of UML to implement proposed method in sensor networks that is dynamic system. We can understand exact flow for each function of the proposed method in node position estimation system can be implemented easily. And we can be confirmed that the position of estimated nodes has a little error.

• Journal of Korea Multimedia Society
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• v.9 no.11
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• pp.1474-1482
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• 2006

Recently, it is advanced about the variable research of IPv6 and the wireless sensor network. However, the existed researches are not enough about the internetworking technology between the wireless sensor network and the Internet based on IPv6 for supporting ubiquitous service. Accordingly, this paper proposes two internetworking models for connecting the wireless sensor network and Internet based on IPv6. The relay router in the first model and the sink node of the wireless sensor network in the second mode] were used as a gateway. Then we analyze and compare with two internetworking models. Additionally we construct the test-bed connected between the wireless sensor network and KOREN(KOrea advanced REsearch Network) based on IPv6 using the first model. And we verified the operation of the test-bed by experiments.

• Journal of Korea Multimedia Society
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• v.14 no.10
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• pp.1287-1302
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• 2011

Clustering protocol that is used in wireless sensor network is an efficient method that extends the lifetime of the network. However, when this method is applied to an environment in which collected data of the sensor node easily overlap, sensor nodes unnecessarily consumes energy. In the case of clustering technique that uses a threshold, the lifetime of the network is extended but the degree of accuracy of collected data is low. Therefore it is hard to trust the data and improvement is needed. In addition, it is hard for the clustering protocol that uses multi-hop transmission to normally collect data because the selection of a cluster head node occurs at random and therefore the link of nodes is often disconnected. Accordingly this paper suggested a cluster-formation algorithm that reduces unnecessary energy consumption and that works with an alleviated link disconnection. According to the result of performance analysis, the suggested method lets the nodes consume less energy than the existing clustering method and the transmission efficiency is increased and the entire lifetime is prolonged by about 30%.

• Journal of Korea Multimedia Society
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• v.13 no.11
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• pp.1657-1666
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• 2010

Underwater wireless sensor networks (UWSN) need stable efficient data transmission methods because of environmental characteristics such as limited energy resource, limited communication bandwidth, variable propagation delay and so on. In this paper, we explain an enhanced hybrid transmission method that uses a hexagon tessellation with an ideal cell size in a two-dimensional underwater wireless sensor network model (2D) that consists of fixed position sensors on the bottom of the ocean. We also propose an energy efficient sensing and communication coverage method for effective data transmission in a three-dimensional underwater wireless sensor network model (3D) that equips anchored sensors on the bottom of the ocean. Our simulation results show that proposed methods are more energy efficient than the existing methods for each model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1917-1924
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• 2015

Efficient routing algorithm is required to transmit data from source to destination by multi-hop transmission in wireless sensor networks. In the multi-hop transmission, multipath routing can be one of the solutions to cope with the traffic congestion and unstable link condition. In this paper, we propose partial multipath routing which does not establish a secondary full routing path but a partial multipath to complement some poor links, and it can enable stable data transmission and reduce the number of nodes in routing path and the required total power compared with conventional multipath routing.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.295-297
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• 2002

최근 들어, 냉장고, 세탁기, TV 등과 같은 가정내의 가전들을 효과적으로 제어하고, 웹에서의 접근을 위한 홈 네트워크 기술에 많은 관심이 모아지고 있다. 홈 네트워크는 가전, 센서, 스위치, 제어기등과 링크할 수 있으며 멀티미디어 데이터의 전달을 위한 인프라의 제공 및 애플리케이션에 대한 사용자 인터페이스를 제공한다. 이러한 다양한 멀티미디어 데이터를 효과적으로 처리하기 위해서는 홈 게이트웨이가 필요하며, 이러한 홈 게이트웨이에 대한 연구가 활발하게 진행되고 있다. 그러나 다양한 데이터 구조의 처리를 위해 IEEE1394, Bluetooth, LonWorks, WLAN, HomePNA, PLC 둥과 같은 다양한 기술의 사용으로 인해 현재 홈게이트웨이는 매우 복잡한 구조를 가지게 되며, 기기간 상호 운용성도 보장하기 어려운 실정이다. 이에 본 논문에서는 홈 네트웍에서 존재하는 다양한 미디어 데이터를 효과적으로 처리할 수 있는 새로운 홈게이트웨이의 구조를 설계하고, 각각의 미디어 데이터를 인터워킹 가능한 패킷으로 만들어 주는 Media Processor와 서로 다른 미디어간의 인터워킹을 위한 Common Switch Interface의 구조에 대하여 기술한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.859-861
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• 2009

무선 통신, 제한된 자원 (전력, 프로세서, 메모리 등), 신뢰성, 동적인 토폴로지 등의 특성을 갖는 센서 네트워크는 기존의 실시간 시스템과는 많은 차이가 있다. 이러한 센서 네트워크에서 멀티미디어 데이터 처리와 같은 많은 계산을 필요로 하는 어플리케이션이나 실시간 어플리케이션을 개발하기 위해서는 센서 노드들의 데이터 병렬 처리가 필요하다. 비선점형 스케쥴러를 갖는 센서 노드에서 데이터 전송량이 많을 경우 통신을 위한 태스크 생성이 증가하므로 일반 태스크의 실행에도 지연이 발생하게 된다. 자원 제한적인 센서 네트워크에서 에너지 소모나 지연과 같은 성능은 각 센서 노드들에 태스크를 할당하는 방법에 영향을 받는다. 본 연구에서는 병렬 처리에 참여하는 센서 노드들의 에너지 소모량과 지연을 고려한 노드 스케쥴링 기법을 제안한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.365-367
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• 2012

클러스터링 기법은 반복적인 setup phase와 steady phase의 반복으로 네트워크를 재구성하는 방법을 사용하며, 이 방법으로 일부 노드에 부가되는 부하를 네트워크에 분산하여 네트워크를 장시간 동안 안정적으로 유지시키는 방법을 사용한다. 그러나 이러한 방법의 가장 큰 문제는 setup phase에서 소비되는 에너지가 간과할 만한 수준이 아니라는 데에 있다. 이에 몇 논문은 이러한 반복적인 setup을 제거하여 네트워크 성능 향상을 꾀하기도 하였다. 그러나 setup의 에너지 분산 효과를 고려하면, setup phase의 삭제는 바람직하지 않다. 본 논문에서는 고정 주기를 갖고 발생하는 setup phase의 반복을 네트워크 환경에 맞게 적응적으로 발생시키는 방법을 제안한다.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.161-169
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• 2009

The development of Wireless Multimedia Sensor Networks(WMSNs) is getting realized in accordance with the increased demands to provide multimedia data transmission service such as CCTV movie, image chapter information, audio information based on wireless sensor network. It is very important to provide the differentiated quality assurance of service. In this paper, we propose a sensor medium access control protocol based on DSMAC, which provides differentiated Quality of Service(QoS) for delay. A proposed protocol is able to reduce the delay without increasing the energy consumption by adaptively changing the duty cycle according to the buffer occupancy. Simulation results show that the new MAC protocol performs better in terms of latency than S-MAC and DSMAC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.11
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• pp.903-917
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• 2012

For transmitting sensed data, wireless sensor networks have been developed and researched for the improvement of energy efficiency, hence, many MAC protocols in WSN employ the duty cycle mechanism. Since the progressed development of the low power transceiver and processor let the high energy efficiency come true, the delivery of the multimedia data which occurs in area of sensor work should be needed to provide supplemental information. In this paper, we design a new scheme for massive transmission of large multimedia data where the duty cycle is used in contention based MAC protocol, for WMSN. The proposed scheme can be applied into the previous duty cycle mechanism because it provides two operation between normal operation and massive transmission operation. Measuring the buffer status of sender and the condition of current radio channel can be criteria for the decision of the above two operations. This paper shows the results of the experiment by performing the simulation. The target protocol of the experiment is X-MAC which is contention based MAC protocol for WSN. And two approaches, both X-MAC which operates only duty cycle and X-MAC which operates combined massive transmission scheme, are used for the comparative experiment.