• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.69-74
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• 2007

Recently, the demands for the satellite broadband mobile communication services are increased. To provide these services, mobile satellite communication systems for the passengers or crews on the high-speed moving vehicles, are being developed for the last several years especially in the Europe and North America. However, most of these systems can provide only several hundred kbps of transmission rate and this is not enough performance to provide satellite internet service for the group users such as passengers on the high-speed train. Moreover, service availability with these systems is limited to be rather low because they don't have any countermeasure scheme for the N-LOS environment which happens often along the railway. This paper describes mobile broadband satellite communication system, which is on the development, to provide high data-rate internet services to the high-speed trains. This system is applied with the inter-networking scenarios of both satellite/terrestrial network and satellite/gap-filler network so that it can provide seamless service even in the train operating environment, and these inter-networking schemes result in high service availability. And this system also has the countermeasure schemes, such as upper layer FEC and antenna diversity, for the short fading which is occurred periodically on the railway due to the power supplying structures so that it can provide high speed internet services. Mobile DVB-S2 technology which is now being standardized in the DVB is used for the forward-link transmission and DVB-RCS for the return-link.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.5
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• pp.75-82
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• 2021

The number of traffic accidents is about 230,000, and due to non-recurring congestion and high driving speed, the number of deaths per traffic accident on freeways is more than twice compared to other roads. Currently, traffic information is provided based on nodes and links using the centerline of the road, but it does not provide detailed speed information. Recently, installing sensors for vehicles to monitor obstacles and measure location is becoming common not only for autonomous vehicles but also for ordinary vehicles as well. The analysis using large-capacity location-based data from such sensors enables real time service according to processing speed. This study presents an mapping method for individual vehicle data analysis based on space. The processing speed of large-capacity data was increased by using method which applied a quaternary notation basis partition method that splits into two directions of longitude and latitude respectively. As the space partition was processed, the average speed was similar, but the speed standard deviation gradually decreased, and decrease range became smaller after 9th partition.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.775-789
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• 2011

Centering on KTX stations, Korea is implementing specialized development of metropolitan business zones nationwide and is in the process of building the transfer link system of transportation in order to actualize intermodalism nationwide. Daejeon station, hub of high-speed railway requires the effective transportation transfer system considering Daejeon station area reorganization plan and opening of second phase high-speed railway. Based on the analysis of the possibility and validity of building a transit center under the Transportation System Efficiency Act, it is necessary to make a mutual benefit in a regional development by installing the resonable transfer system between railway and other transportation services. Through analysis of current situations and technical, economic and environmental feasibility evaluation, design plan of effective transportation transfer system in Daejeon station is proposed.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.6
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• pp.471-477
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• 2000

The position control accuracy of a robot arm is significantly deteriorated when a long arm robot is operated at a high speed. In this case, the robot arm must be modeled as a flexible structure, not a rigid one, and its control system should be designed with its elastic modes taken into account. In this paper, the tip position control scheme of a one-link flexible manipulator using 2-DOF controller with sliding mode is presented. The robot consists of a flexible arm manufactured with a thin aluminium plate, an AC servo motor with a harmonic drive for speed reduction, an optical encoder and a CCD camera as a vision sensor for on-line measuring the tip deflection of the flexible m. Simulation and experimental results of the flexible manipulator with a proposed controller are provided to show the effectiveness of the controller.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.3
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• pp.127-133
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• 2005

Korean multi-propulsion system consists of a synchronous alternator driven by a gas turbine driving synchronous alternator coupled to a rectifier - DC link - DC/DC converter and traction system based on modification of the G7 high-speed train. The simulation modules include turbine engine system, alternator, rectifier, DC/DC converter and power management module. Simulation for the multi-propulsion system such as a modular is presented in order to confirm the system stability for loads with uncertain input impedances and control loop speeds. This paper deals with various simulation modules with a specific control loop to help the development of the real lame-scaled system.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.467-469
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• 2006

In wireless network environments, as users' demands on high-speed data communications due to increase of multi-media services, the necessity of new high-speed WLAN technologies has appeared. Nowaday, IEEE is standardizing a new WLAN protocol caned as IEEE 802.11n. To effectively use wireless resources, IEEE 802.11n introduces MAC aggregation function which is similar to that in IEEE 802.11e. In case of transmitting several frames without MAC aggregation, the frames include individual frame header and trailer, and their corresponding acknowledgement frames can appear on wireless link. However, if they are aggregated into single MAC frame, we can reduce the number of used bits due to frame headers/trailers and also remove redundant acknowledgement frames. In this paper, we explain two different MAC frame aggregation methods for IEEE 802.11e and IEEE 802.11n and evaluate their throughput by simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.229-232
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• 1996

The position control accuracy of the robot arm is decreased significantly when a long arm robot is operated at high speed. In this case, the robot arm must be modeled as a flexible structure, not a rigid one, and its control system will be necessarily designed with its elastic modes taken into account. In this paper, the vibration control of a one-link flexible robot arm is presented. The robot system consists of a flexible arm manufactured with thin aluminium plate, AC servomotor with a harmonic drive for speed reduction, optical encoder and accelerometer. The system is modeled with limited number of elastic modes, and its parameters are determined from the results of the experiments. The implemented control schemes are LQ control and sliding mode control. The experiments and digital simulations are carried out to test the validity of the system modeling, controller design, and active control implementation.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.3
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• pp.151-156
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• 2012

When mounting the sensor device in the way of Plug&Play, sensor device drivers need to be loaded and linked dynamically. Since a sensor node platform is based on small 8 bit MCU, dynamic loading and linking technique used in Windows and Linux can not be applied. In this paper, we present how to link and load dynamically sensor device drivers for sensor device Plug&Play. We implement a prototype and evaluate it to make sure that there is no performance degradation like sensor device driver connection speed and memory usage. Connection speed overhead increases to 0.2ms. Memory usage overhead increases to hundreds byte. It shows that there is no heavy influence in running the actual program.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.2
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• pp.220-227
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• 1999

The position control accuracy of a robot arm is significantly deteriorated when a long slender arm robot is operated at a high speed. In this case, the robot arm needs to be modeled as a flexible structure, not a rigid one, and its control system needs to be designed with its elastic modes taken into account. In this paper, the vibration control scheme of a one-link flexible manipulator using adaptive input shaper in conjunction with PID controller is presented. The robot consists of a flexible arm manufactured with a thin aluminium plate, an AC servo motor with a harmonic drive for speed reduction, an optical encoder and an accelerometer. On-line identification of the vibration mode is done using the pruned decimation-in-time FFT algorithm to estimate the parameter of the input shaper. Experimental results of the flexible manipulator with a PID controller and input shaper are provided to show the effectiveness of the advocated controllers.

• Journal of Industrial Technology
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• v.15
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• pp.113-122
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• 1995

By integrating WDM to OPS unit which plays an important role for the reliability of CPN, we made it possible to provide CATV, VOD, and high-speed data services simultaneously and to meet the requirements for new services in the future. For the design of optimal system, the link analysis of power budget has been performed. Also, the prototyped system has been tested with STM-1 level signals to confirm functions such as transmission, distribution, and protection. The results proved that when occurred out-of-order or recovery of ONU, the system did the pertinent switching with minimum loss for high-speed data services. Also for video distribution services, the system has distributed STM-1 level signals successfully.