• Journal of information and communication convergence engineering
• /
• 제8권2호
• /
• pp.212-218
• /
• 2010

In wireless sensor networks (WSNs), both efficient energy management and Quality of Service (QoS) are important issues for some applications. For creating robust networks, real-time services are usually employed to satisfy the QoS requirements. In this paper, we proposed a hierarchical real-time MAC (medium access control) protocol for (m,k)-firm constraint in wireless sensor networks shortly called HRTS-MAC. The proposed HRTS-MAC protocol is based on a dynamic priority assignment by (m,k)-firm constraint. In a tree structure topology, the scheduling algorithm assigns uniform transmitting opportunities to each node. The paper also provides experimental results and comparison of the proposed protocol with E_DBP scheduling algorithm.

• 센서학회지
• /
• 제26권1호
• /
• pp.1-6
• /
• 2017

The advanced driver assistant system (ADAS) requires the collection of a large amount of information including road conditions, environment, vehicle status, condition of the driver, and other useful data. In this regard, large-scale sensor networks can be an appropriate solution since they have been designed for this purpose. Recent advances in sensor network technology have enabled the management and monitoring of large-scale tasks such as the monitoring of road surface temperature on a highway. In this paper, we consider the estimation and fusion problems of the large-scale sensor networks used in the ADAS. Hierarchical fusion architecture is proposed for an arbitrary topology of the large-scale sensor network. A robust cluster estimator is proposed to achieve robustness of the network against outliers or failure of sensors. Lastly, a robust hierarchical data fusion scheme is proposed for the communication channel between the clusters and fusion center, considering the non-Gaussian channel noise, which is typical in communication systems.

• Journal of Information Technology Applications and Management
• /
• 제12권4호
• /
• pp.13-24
• /
• 2005

The sensor network is a key component of the ubiquitous computing system which is expected to be widely utilized in logistics control, environment/disaster control, medical/health-care services, digital home and other applications. Nodes in the sensor network are small-sized and exposed to adverse environments. They are demanded to perform their missions with very limited power supply only. Also the sensor network is composed of much more nodes than the wireless ad hoc networks are. In case that some nodes consume up their power capacity, the network topology should change, and rerouting/retransmission is necessitated. Communication protocols studied for conventional wireless networks or ad hoc networks are not suited for the sensor network resultantly. Schemes should be devised to control the efficient usage of node power in the sensor network. This paper proposes a medium access protocol to enhance the efficiency of energy consumption in the sensor network node. Its performance is analyzed by simulation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
• /
• pp.296-298
• /
• 2008

Currently SCADA System faces various fault situation. Operator must recognize all fault state and management plans. But it is not easy to recognize all category and acquired error data. So it is needed that automatic fault estimation. Automatic fault estimation is possible to data flow control. Data flow control method is two type. One is alarm processing and the other one is topology processing. This paper provide two type processing method in SCADA data flow control.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2011년도 전력전자학술대회
• /
• pp.23-24
• /
• 2011

In this paper, the 170W LLC half bridge DC-DC converter is designed for the lighting management system. The power conversion circuit consists of PFC and isolated LLC resonant converter. The topology of LLC half bridge resonant converter provides ZVS characteristic. And the stresses of voltage and current is smaller than that of the general resonant converters. So we can expect the higher efficiency. The optimal conditions for high efficiency were investigated through by experiment.

• 환경영향평가
• /
• 제16권4호
• /
• pp.285-300
• /
• 2007

The purpose of this study was to ascertain the ecological state and problems of eco-bridges on Korean roads. The study was conducted from March to April 2007 by checking ecological factors and wildlife around the eco-bridges and habitats. 8 representative eco-bridges were selected by their bridge shape and condition of location. After field survey, we analyzed ideal trails for wildlife using field data, digital topology maps, satellite images, and land use map. In addition to trail analysis, we identified the propriety of the eco-bridges through Population Viability Analysis. Because of unsuitable location and management, we found that most of the bridges are not proper for wildlife dispersal. Moreover, in some habitats, we could expect that some local populations might be extinct without appropriate treatments.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
• /
• pp.346-349
• /
• 2004

The design of DC-DC converters for power electronic interfaces in power management systems for Hybrid Electric Vehicle (HEV) is a very challenging task. In this paper, the considered topology is the hi-directional buck-boost converter and inverter system. If we make the converter side DC link current the same as the inverter side DC link current in a converter-inverter system, no current will flow through the BC link capacitor and as a result, no DC link voltage variation occurs. This leads to the possibility of reducing small th size of DC link capacitors which are expensive, bulky. Therefore we propose the converter current controller which can manage to match inverter and converter current at the DC link.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2012년도 추계학술대회 논문집
• /
• pp.63-64
• /
• 2012

In this paper, design relatively lightweight dual inverter SAW welding power system, compared to former large and weight system. In addition, we propose welding system topology with pulse frequency, width and current management through applying inverter to ouput.

• Journal of Information Technology Applications and Management
• /
• 제10권2호
• /
• pp.61-71
• /
• 2003

Ad-hoc networks are characterized by multi-hop wireless links, frequently changing network topology and the need for efficient dynamic routing protocols. In an Ad-hoc network, each host assumes the role of a router and relays packets toward final destinations Because a packet is broadcast to all neighboring nodes, the optimality criteria of wireless network routing is different from that of wired network routing. tn this paper 1 point out the more important cost factor than the number of links in the Ad-hoc network. A class routing protocols called on-demand protocols has recently found attention because of their low routing overhead since it performs a blind flooding to look for a path. In this paper, 1 propose the method which reduces overhead by using the information of neighboring nodes and doing a selective flooding. Simulation results demonstrate better reduction of routing overheads with this scheme.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -2
• /
• pp.830-833
• /
• 2002

To solve the internal security problem such as human error and bad faith, the automation of computer system management is significant. For this purpose, we focus attention in the automation of Mail Delivery Service. Today, requirement for reliable mail delivery system becomes larger and larger. However, existing systems are too strict about their configuration. Hence, we propose the method based on Reinforcement Learning (RL) to achieve proper MX record ordering. A measure on validity of the design of system, such as network topology number of servers and so on, is also obtained as side benefit. In order to verify the usability of the presented method, we did on a small model of mail delivery system. As a result, we show that RL is available for determination of the proper MX record ordering. Additionally, we suggest that it is also available for comparing validity of setting of MTA and the network design.