• 한국항행학회논문지
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• 제16권2호
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• pp.271-277
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• 2012

본 논문에서는 재난모니터링, 환경감시 및 재난구호 등의 정보 수집 및 정찰 등의 임무를 수행하는 다수의 UAV들로 구성된 편대비행 네트워크를 위해 동적 트리 형성 프로토콜을 제안하였다. 특히 무선 동적 환경에 적응한 최적의 트리를 구성하기 위한 링크 비용을 구하기 위해 거리에 따른 무선 신호 감쇄현상을 적용하여 Hop-LQI Weight 알고리즘을 고안하였으며 이를 MSP430 K-mote 센서 플랫폼에 TinyOS 코드를 구현하였다. 이를 무선 통신에서 링크 비용 산출 기법인 Minimum LQI 방법과 노드 수에 따른 평균 경로 설정시간을 비교를 통하여 성능을 검증하였다.

• 한국정보처리학회논문지
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• 제7권4호
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• pp.1217-1226
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• 2000

Traditionally, Mobile Teletraffic model consists of two sub-models, i.e. the network traffic model and the traffic source model. In this paper, we present the traffic source model by developing MobCall (Mobile Call Simulator) which analyses various mobile wireless environments based on regional characteristics that the base stations are located. User mobility is presented by regional average vehicle speeds and the transportation share rate. Moreover, the user mobility on subway, which is increasing in urban area, is considered in MobCall. And also, user's movements on highway are considered in MobCall. The object-oriented simulation platform, C++SIM, is used to implement MobCall. Using MobCall, the accumulated number of calls in residential and commercial regions, the handoff rate with respect to traffic sources of Seoul, the handoff rate on highway, and the handoff rate according to the call duration are presented. MobCall enables the simulation of dynamic handoff buffering and functional entity control of one base station according to the changes in user's calling pattern at the design phase. Also, when a new town is under construction by a detailed plan, MobCall is used to design the mobile network with regional characteristics and user mobility considered.

• 유공압시스템학회논문집
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• 제4권3호
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• pp.13-21
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• 2007

A forklift is a motive machine powered by LPG, diesel engine or electric motors. The internal combustion engine type forklift is equipped with automatic transmission to meet the required drive load as well as the easy operation of the vehicle. This paper deals with the shift control and endurance test controller which is developed for the functional test of the newly designed automatic transmission on a dynamometer test bench. Its major function is to control the proportional solenoid currents, which is directly related to clutch pressures, for the given reference current trajectory during shift and sequential operation of shift schedule designed for the durability test at each gear. It also has the ability to monitor all the necessary test data through RS232 communication and log them to disk files. The current controller of embedded system is designed from the identified dynamics of solenoid coil and the current reference can be easily modified with a user interface software on PC so as to match the shift data by experiments.

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.463-474
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• 2015

Future Ground Control Stations (GCSs) for Unmanned Aerial Vehicles (UAVs) teleoperation targets better situational awareness by providing extra motion cues to stimulate the vestibular system. This paper proposes a new virtual environment for long range Unmanned Aerial Vehicle (UAV) control via Non-Line-of-Sight (NLoS) communications, which is based on motion platforms. It generates motion cues for the teleoperator for extra sensory stimulation to enhance the guidance performance. The proposed environment employs the distributed component simulation over GSM network as a simulation platform. GSM communications are utilized as a multi-hop communication network, which is similar to global satellite communications. It considers a UAV mathematical model and wind turbulence effects to simulate a realistic UAV dynamics. Moreover, the proposed virtual environment simulates a Multiple Axis Rotating Device (MARD) as Human Machine Interface (HMI) device to provide a complete delay analysis. The demonstrated measurements cover Graphical User Interface (GUI) capabilities, NLoS GSM communications delay, MARD performance, and different software workload. The proposed virtual environment succeeded to provide visual and vestibular feedbacks for teleoperators via GSM networks. The overall system performance is acceptable relative to other Line-of-Sight (LoS) systems, which promises a good potential for future long range, medium altitude UAV teleoperation researches.

• 제어로봇시스템학회논문지
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• 제7권4호
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• pp.326-333
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• 2001

This paper focuses on a method to connect mobile devices such as mobile robot. Automated Guided Vehicle (AGV) and Unmanned Container Transporter(UCT) to a fieldbus. In this paper, the IEEE 802.11 wireless LAN is used to extend a Profibus network for the mobile devices. In order to integrate these two networks, a gateway is developed using two threads and an internal buffer. Furthermore, a polling algorithm is applied at the gateway in order to satisfy real-time requirements on data communication, Finally, the performance measures such as data latency and throughput are experimentally evaluated on a wirelessly-extended Profibus network. The results shows the feasibility of the wireless extension of Profilbus for various mobile device.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권8호
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• pp.1388-1403
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• 2011

A vehicular ad-hoc network (VANET) consists of vehicles that form a network without any additional infrastructure, thus allowing the vehicles to communicate with each other. VANETs have unique characteristics, including high node mobility and rapidly changing network topology. Because of these characteristics, routing algorithms based on greedy forwarding such as greedy perimeter stateless routing (GPSR) are known to be very suitable for a VANET. However, greedy forwarding just selects the node nearest to the destination node as a relay node within its transmission range. This increases the possibility of a local maximum and link loss because of the high mobility of vehicles and the road characteristics in urban areas. Therefore, this paper proposes a reliability-improving position-based routing (RIPR) algorithm to solve those problems. The RIPR algorithm predicts the positions, velocities, and moving directions of vehicles after receiving beacon messages, and estimates information about road characteristics to select the relay node. Thus, it can reduce the possibility of getting a local maximum and link breakage. Simulation results using ns-2 revealed that the proposed routing protocol performs much better than the existing routing protocols based on greedy forwarding.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.542-558
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• 2016

Vehicular Ad Hoc Networks (VANETs) are self-configuring networks where the nodes are vehicles equipped with wireless communication technologies. In such networks, limitation of signal coverage and fast topology changes impose difficulties to the proper functioning of the routing protocols. Traditional Mobile Ad Hoc Networks (MANET) routing protocols lose their performance, when communicating between vehicles, compromising information exchange. Obviously, most applications critically rely on routing protocols. Thus, in this work, we propose a methodology for investigating the performance of well-established protocols for MANETs in the VANET arena and, at the same time, we introduce a routing protocol, called Genetic Network Protocol (G-NET). It is based in part on Dynamic Source Routing Protocol (DSR) and on the use of Genetic Algorithms (GAs) for maintenance and route optimization. As G-NET update routes periodically, this work investigates its performance compared to DSR and Ad Hoc on demand Distance Vector (AODV). For more realistic simulation of vehicle movement in urban environments, an analysis was performed by using the VanetMobiSim mobility generator and the Network Simulator (NS-3). Experiments were conducted with different number of vehicles and the results show that, despite the increased routing overhead with respect to DSR, G-NET is better than AODV and provides comparable data delivery rate to the other protocols in the analyzed scenarios.

• 한국통신학회논문지
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• 제40권7호
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• pp.1248-1256
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• 2015

강우에 취약한 특성을 갖는 Ku대역을 이용한 통신 링크 설계 시에는 반드시 정확한 데이터와 정밀한 예측모델을 이용하여 도출한 강우감쇠 값을 반영하여 링크 마진을 분석하여야 한다. 따라서 본 논문에서는 최근 TTA에서 제시한 국내 강우강도 분포를 분석하여 Rec. ITU-R PN.837-1 및 Crane 모델에서의 지역별 강우강도와 비교하고, 우리나라의 최근 강우강도 분포와 유사한 지역을 선택하여 Ku대역 주파수에 대한 해당 지역의 강우감쇠를 Rec. ITU-R P.618-8와 Crane 강우감쇠 예측 모델을 통해 무인항공기와 지상통신장비의 통신 링크 거리 및 연 시간율 (%)에 따라 분석한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2353-2356
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• 2002

The increase of vehicles stagnations leads to the increasing attention to the way customers pay and a large number of projects on electronic cash system. Tranport system is comprised of a number of advanced technologies, including information processing, communications, control, and electronics. Recently many research on a system which provides contact in order to protect driver's vehicle passage have been carried out. And some potential problems from that system are being reviewed by electronic cash system. In this papers, we suggest RF protocol developing technology using the concept of electronic cash. ATM electronic cash developing is consist of component of pre-developed coin throw, integration of component using its, and production of more requirement-satisfactory ITS solution. Result increase 15$\sim$40% pre-type vehicles stagnations. Especially, we expect this proposed concept would be well adapted to our national environments.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1060-1066
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• 2008

Bi-modal tram is a new conceptual transit mean for public transportation integrating thoroughfare and railroad vehicle's characteristics together. This paper describes about a software design which will be applied to an automatic driving system, which is called NCS (Navigation Control System), considering such multiplicity of mechanical characteristic. The NCS adopts propulsion, braking, and direction control functions for a tram and utilizes various sensors to fully take control over such functions. In this paper, we defined and analyzed the capabilities of the NCS. Those capabilities are designed with a UML 2.0 based object-oriented modeling technique. Moreover, to ensure the complete operation of such capabilities, a communication protocol (which is capable of controlling sensors, propulsion, brakes, and traveling directions) is designed here. Throughout the paper, firstly, all the NCS related functions are discussed in accordance with the equipments they are belonged to; secondly the UML modeling application techniques for the defined functions and protocols for the communications between equipments are introduced; and lastly a validation process for the design specifications is going to be discussed.