• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.30-45
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• 2014

Recently, multimedia application users who demand for ubiquitous computing environment are rapidly increasing, and wireless mesh network is receiving attention as a cost-effective key technology for next generation wireless networking. When multiple flows are transmitting data at the same time in the network, routing for path selection of each flow and link resource allocation for data transmission of each flow are one of the key factors that influence to the effectiveness of the network directly. In this paper, we consider problems for path discovery and resource allocation of links at the same time and we propose an algorithm based on mathematical modeling using a technique for cross-layer optimization design in STDMA-based wireless mesh networks that can enhance transfer performance for each flow. We show by performance analysis that the proposed algorithm can enhance the throughput performance by maximally utilizing given bandwidth resources when the number of flows increase in multi-hop wireless mesh networks.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.525-539
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• 2020

A site containing buried solid waste and treated water and oil storage containers from a leather manufacturing plant was studied through soil and groundwater pollution and electrical resistivity surveys with the aim of identifying areas polluted by leachate generated by landfilling with leather waste and leakage wastewater. It was found that TPH and Zn exceeded environmental standards for soil pollution and, for leachate and groundwater, Cr(VI) concentrations exceeded standard levels for groundwater quality. An electrical resistivity survey was used to elucidate soil and groundwater pollution characteristics and diffusion pathways. Ten survey lines were set up with an electrode spacing of 5 m in a dipole-dipole array. The hydraulic characteristics of soil determined by groundwater contamination surveys matched well the low-resistivity-anomaly zones. Electrical resistivity surveys of areas containing contaminated soil and groundwater that have irregular strata due to waste reclamation are thus useful in highlighting vertical and horizontal pollutant diffusion pathways and in monitoring contaminated and potentially contaminated areas.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.696-704
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• 2011

In this paper, we propose a mobile robot navigation algorithm using data fusion of a monocular camera and ultrasonic sensors. Threshold values for binary image processing are generated by a fuzzy inference method using image data and data of ultrasonic sensors. Threshold value variations improve obstacle detection for mobile robot to move to the goal under poor illumination environments. Obstacles detected by data fusion of camera and ultrasonic sensors are expressed on the grid map and avoided using the circular planning algorithm. The performance of the proposed method is evaluated by experiments on the Pioneer 2-DX mobile robot in the indoor room with poor lights and a narrow corridor.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1737_1738
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• 2009

미사일의 표적 충돌각을 원하는 각도로 제어하는 것은 표적의 취약점을 공략하기 위해 필수적인 기술이다. 표적 타격 지점 및 충돌각을 고려하지 않으면 타격에 성공하였다고 하더라도 표적의 방어 능력이 좋거나 신관이 충돌각에 민감하면 표적의 효과적인 파괴에 실패할 수도 있다. 이런 경우 유도 미사일의 종말 유도 효율을 증가시키기 위해 미사일이 표적을 타격하는 각도인 표적 충돌각(Impact Angle)을 제어할 수 있으면 적정 비행경로의 설정에 유리하고 우회공격 등이 가능할 뿐 아니라 미사일 탄두의 효과를 극대화할 수 있다. 하지만 이러한 장점을 갖는 표적 충돌각 유도 기법에 대한 연구는 아직 활발하게 행해지고 있지는 못하다. 기존 연구 결과들은 2차원 평면상에서의 충돌각 제어만을 다루고 있어, 요와 피치 채널의 커플링 문제가 있는 BTT 미사일에 적용하기가 어렵다는 문제점을 갖고 있다. 또한 미사일 동역학을 무시하거나 단순화하여 문제를 풀고 있기 때문에 실제 상황에 적용이 어렵다는 단점이 있다. 본 논문에서는 3차원 공간상에서의 롤 명령을 모두 포함하면서 동시에 미사일 자동조종제어기, 핀 구동기 동역학을 모두 고려한 새로운 BTT 미사일의 표적 충돌각 유도 기법을 제안한다.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.185-192
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• 2012

Line planning is to determine the frequency of trains on each line to satisfy origin-destination demand while minimizing total operation cost. However, different from the line planning in passenger transportation, it is more important at which intermediate stations each train should be stopped and shunted because the freight car handling works like drop-off or(and) pick-up can incur much time and high cost so that the delay deteriorates the quality of rail freight transportation service. We present an optimization model for constructing line plan in rail freight transportation to simultaneously minimize the train operation cost and total transportation time of freights. And we suggest a column generation approach for our problem, which can solve the real network instances in reasonable computation times.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.878-885
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• 2011

Due to reflect at surface of the water and limit bandwidth, it is difficult to design underwater acoustic communication systems with high-reliability and high transmission rate. Therefore the trends of underwater communication is transformed from single sensor to multiple sensor studies. However, underwater MIMO communication techniques have a high correlation value between multiple sensors on transmitters and receivers in underwater environments, it is difficult to expect space diversity gain on muli-path channels. Therefore, this paper proposed the MISO communications system with two transmit sensors and single receiver sensor, and analyzed its performance using the LDPC codes and channel compensation algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.871-874
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• 2008

이동성을 제공하기 위한 프로토콜 중 오랜 기간 많은 연구로 표준화가 된 Mobile IPv6 (MIPv6)가 있다. MIPv6는 호스트 기반 이동성 제공 프로토콜로서 이동 단말이 이동성에 필요한 시그널링을 직접수행한다. 한편, 최근에 표준화 작업이 진행 중인 Proxy Mobile IPv6 (PMIPv6)는 네트워크 기반 이동성 제공 프로토콜로서 이동 단말이 아닌 네트워크 자체에서 이동성을 제공한다. PMIPv6는 MIPv6에서 Home Agent와 같은 역할을 하는 Local Mobility Anchor 와 이동 단말이 수행하던 시그널링을 대신하는 Mobile Access Gateway를 정의하여 이동성을 제공한다. PMIPv6의 기본 동작 과정에 대한 표준화가 진행됨에 따라 프로토콜의 최적화에 대한 이슈가 부각되고 있다. Route Optimization은 이러한 최적화 이슈 중 하나로서 패킷 전송 시 최적화 된 경로를 설정하고 발생할 수 있는 전송 지연을 최소화하는 기법이다. 본 논문에서는 PMIPv6에서의 Route Optimization을 적용하기 위해 Liebesch 인터넷 드래프트에서 제안 한 기법의 동작 과정을 살펴보고 PMIPv6의 기본 전송 과정과 비교하여 그 성능을 분석하였다.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.6
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• pp.558-564
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• 2013

Wireless sensor networks (WSNs) contain limited energy resources and are left in open environments. Since these sensor nodes are self-operated, attacks such as sinkhole attacks are possible as they can be compromised by an adversary. The sinkhole attack may cause to change initially constructed routing paths, and capture of significant information at the compromised node. A localized encryption and authentication protocol (LEAP) has been proposed to authenticate packets and node states by using four types of keys against the sinkhole attack. Even though this novel approach can securely transmits the packets to a base station, the packets are forwarded along the constructed paths without checking the next hop node states. In this paper, we propose the next hop node selection method to cater this problem. Our proposed method evaluates the next hop node considering three factors (i.e., remaining energy level, number of shared keys, and number of filtered false packets). When the suitability criterion for next hop node selection is satisfied against a fix threshold value, the packet is forwarded to the next hop node. We aim to enhance energy efficiency and a detour of attacked areas to be effectively selected Experimental results demonstrate validity of the proposed method with up to 6% energy saving against the sinkhole attack as compared to the LEAP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.617-623
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• 2018

In this paper, we propose a novel seamless video composition method based on shape matching and Poisson equation. Video composition method consists of video segmentation process and video blending process. In the video segmentation process, the user first sets a trimap for the first frame, and then performs a grab-cut algorithm. Next, considering that the performance of video segmentation may be reduced if the color, brightness and texture of the object and the background are similar, the object region segmented in the current frame is corrected through shape matching between the objects of the current frame and the previous frame. In the video blending process, the object of source video and the background of target video are blended seamlessly using Poisson equation, and the object is located according to the movement path set by the user. Simulation results show that the proposed method has better performance not only in the naturalness of the composite video but also in computational time.

• The KIPS Transactions:PartD
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• v.12D no.2 s.98
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• pp.259-266
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• 2005

Recently data centric routing or application dependent routing protocols are emerged in mobile ad hoc networks. In this paper, we propose a routing method for query processing in MANET(Mobile Ad hoc NETwork) environment, called road-based query routing, with consideration on real time traffic information of large number of vehicles. In particular, we focus on the method that process arrival time dependent shortest path query in MANET without a central server on the road networks. The main idea of our approach lies in a routing message that includes query predicates based on the road connectivity and on data gathering method in real time from vehicles on the road by ad-hoc network. We unify route discovery phase and data delivery(query processing) phase in our mechanism and reduce unnecessary flooding messages by pruning mobile nodes which are not on the same or neighboring road segments. In order to evaluate the performances of the proposed method, we established a model of road networks and mobile nodes which travel along the roads. The measurement factor is the number of nodes to whom route request is propagated according to each pruning strategy. Simulation result shows that road information is a dominant factor to reduce the number of messages.