Daegu Gyeongbuk Research Center

Daegu, South Korea

Daegu Gyeongbuk Research Center

Daegu, South Korea

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Baek J.W.,Daegu Gyeongbuk Research Center | Kwon K.-K.,Daegu Gyeongbuk Research Center | Lee S.-I.,Daegu Gyeongbuk Research Center | Seo D.-W.,Kyungpook National University
IEICE Transactions on Communications | Year: 2014

This paper proposes a reliable data aggregation scheduling that uses caching and re-transmission based on track topology. In the proposed scheme, a node detects packet losses by overhearing messages that includes error indications of the child nodes, from its neighbor nodes. If packet losses are detected, as a backup parent, the node retransmits the lost packet. A retransmission strategy is added into the adaptive timeout scheduling scheme, which adaptively configures both the timeout and the collection period according to the potential level of an event occurrence. The retransmission steps cause an additional delay and power consumption of the sensor nodes, but dramatically increase the data accuracy of the aggregation results. An extensive simulation under various workloads shows that the proposed scheme outperforms other schemes in terms of data accuracy and energy consumption. Copyright © 2014 The Institute of Electronics, Information and Communication Engineers.


Baek J.W.,Daegu Gyeongbuk Research Center | Nam Y.J.,Daegu University | Seo D.-W.,Kyungpook National University
IEICE Transactions on Communications | Year: 2010

Wireless sensor networks are subject to node and link failures for a variety of reasons. This paper proposes a k-disjoint-path routing algorithm that varies the number of disjoint paths (k) in order to meet a target-delivery ratio of critical events and to reduce energy consumption. The proposed algorithm sends packets to the base station through a single path without the occurrence of critical events, however, it sends packets to the base station through k disjoint paths (k > 1) under the occurrence of critical events, where k is computed from a well-defined fault model. The proposed algorithm detects the occurrence of critical events by monitoring collected data patterns. The simulation results reveal that the proposed algorithm is more resilient to random node failure and patterned failure than other routing algorithms and it also decreases energy consumption much more than the multi-path and path-repair algorithms. © 2010 The Institute of Electronics.


Baek J.W.,Daegu Gyeongbuk Research Center | Nam Y.J.,Daegu University | Seo D.-W.,Kyungpook National University
IEICE Transactions on Communications | Year: 2012

This paper proposes a novel routing algorithm that constructs position-based k-disjoint paths to realize greater resiliency to patterned failure. The proposed algorithm constructs k-disjoint paths that are spatially distributed by using the hop-count based positioning system. Simulation results reveal that the proposed algorithm is more resilient to patterned failure than other routing algorithms, while it has low power consumption and small delay. Copyright © 2012 The Institute of Electronics, Information and Communication Engineers.


Baek J.W.,Daegu Gyeongbuk Research Center | Nam Y.J.,Daegu University | Seo D.-W.,Kyungpook National University
IEICE Transactions on Communications | Year: 2012

In this paper, we propose a novel in-network aggregation scheduling scheme for forest fire monitoring in a wireless sensor network. This adaptively configures both the timeout and the collecting period according to the potential level of a fire occurrence. At normal times, the proposed scheme decreases a timeout that is a wait time for packets sent from child nodes and makes the collecting period longer. That reduces the dissipated energy of the sensor node. Conversely, the proposed scheme increases the timeout and makes the collecting period shorter during fire occurrences in order to achieve more accurate data aggregation and early fire detection. Copyright © 2012 The Institute of Electronics, Information and Communication Engineers.


Seo D.-W.,Daegu Gyeongbuk Research Center | Lee J.-H.,Daegu Gyeongbuk Research Center | Lee H.S.,Daegu Gyeongbuk Research Center
ETRI Journal | Year: 2016

A wireless power transfer (WPT) system is usually classified as being of either a two-coil or four-coil type. It is known that two-coil WPT systems are suitable for shortrange transmissions, whereas four-coil WPT systems are suitable for mid-range transmissions. However, this paper reveals that the two aforementioned types of WPT system are alike in terms of their performance and characteristics, differing only when it comes to their matching-network configurations. In this paper, we first find the optimum load and source conditions using Z-parameters. Then, we estimate the maximum power transfer efficiency under the optimum load and source conditions, and we describe how to configure the matching networks pertaining to both types of WPT system for the given optimum load and source conditions. The two types of WPT system show the same performance with respect to the coupling coefficient and load impedance. Further, they also demonstrate an identical performance in the two cases considered in this paper, that is, a strong-coupled case and a weak-coupled case. © 2016 ETRI.


Seo D.-W.,Daegu Gyeongbuk Research Center | Lee J.-H.,Daegu Gyeongbuk Research Center | Lee H.,Daegu Gyeongbuk Research Center
ETRI Journal | Year: 2016

A wireless power transfer (WPT) system is generally designed with the optimum source and load impedance in order to achieve the maximum power transfer efficiency (PTE) at a specific coupling coefficient. Empirically or intuitively, however, it is well known that a high PTE can be attained by adjusting either the source or load impedance. In this paper, we estimate the maximum achievable PTE of WPT systems with the given load impedance, and propose the condition of source impedance for the maximum PTE. This condition can be reciprocally applied to the load impedance of a WPT system with the given source impedance. First, we review the transducer power gain of a two-port network as the PTE of the WPT system. Next, we derive two candidate conditions, the critical coupling and the optimum conditions, from the transducer power gain. Finally, we compare the two conditions carefully, and the results therefore indicate that the optimum condition is more suitable for a highly efficient WPT system with a given load impedance. © 2016 ETRI.


Baek J.W.,Automotive IT Platform Research Section | Kwon K.-K.,Automotive IT Platform Research Section | Lee S.-I.,Daegu Gyeongbuk Research Center
Proceedings of the International Symposium on Consumer Electronics, ISCE | Year: 2014

This paper proposes a novel on-road vehicle detection algorithm for Advanced Driver Assistance Systems. The proposed algorithm uses shadow and edge information of original image to generate the candidate vehicles. The proposed algorithm extracts the shadow region darker than the road, and creates an edge image using the Canny edge detector. It performs AND operation between the shadow image and the edge image. The candidate vehicles are verified by SVM classifier based on the HOG feature vector. The experimental results show that the proposed algorithm provides fast and accurate vehicle detection. And the number of candidates is reasonable for the vehicle verification. © 2014 IEEE.


Baek J.W.,Smart Vision Research Section | Han B.-G.,Smart Vision Research Section | Kang H.,Smart Vision Research Section | Chung Y.,Smart Vision Research Section | Lee S.-I.,Daegu Gyeongbuk Research Center
International Conference on Ubiquitous and Future Networks, ICUFN | Year: 2016

In this paper, we proposes a novel tracking algorithm combining Kalman Filter with mean-shift. Kalman Filter predicts the vehicle position in the next frame. Mean-shift finds the best candidate which has maximum similarity with the tracked vehicle in the predicted area. Kalman Filter updates its state value of vehicle position with the position of the best candidate from the mean-shift tracker. As a result, the proposed algorithm tracks the vehicle without local maximum problem of mean-shift tracker. The proposed algorithm is very fast because it does not perform the redetection process, and it has no detection misses because it finds the best candidate which has maximum similarity with the tracked vehicle in the predicted area. Also, the proposed algorithm has deleting and adding policies for the tracking list management. If a vehicle was consecutively detected in the previous frames, the proposed algorithm assumes that the vehicle exists although the vehicle is not detected in the predicted region at the current frame. If a vehicle was not detected in the previous frames consecutively, the proposed algorithm assumes that the vehicle does not exist although the vehicle is detected in the current frame. We evaluated the performance of the proposed algorithm in terms of processing time and detection ratio. At target board, the proposed algorithm has 40 frames per second, which meets the real time requirements of the ADAS systems. The detection ratio and processing time of the proposed algorithm outperformed our former work. © 2016 IEEE.


Seo D.-W.,Daegu Gyeongbuk Research Center | Khang S.-T.,Korea Advanced Institute of Science and Technology | Chae S.-C.,Korea Advanced Institute of Science and Technology | Yu J.-W.,Korea Advanced Institute of Science and Technology | And 2 more authors.
Microwave and Optical Technology Letters | Year: 2016

An open-loop self-adaptive wireless power transfer system using magnetic resonance coupling for implantable biosensors, which provides stable wireless power regardless of variations in operating distance and lateral misalignment between the transmitting and receiving antennas, is proposed. According to adaptive impedance matching algorithms under the minimum reflected power conditions, the proposed system achieves an improved power transfer efficiency of maximum 47% within the operating distance. © 2016 Wiley Periodicals, Inc.

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