• Journal of the Institute of Convergence Signal Processing
• /
• v.12 no.4
• /
• pp.286-290
• /
• 2011

LBS(Location Based System) is the essential technology of ubiquitous market and utilizes the GNSS(Global Navigation Satellite). GNSS includes GPS of USA, Galileo of Europe Union, QZSS of Japan, Compass of China, and IRNSS of India. Related researches have recently been conducted. Once the satellite is launched, the maintenance such as modification and verification of its function is difficult. Therefore, before the launch of satellites, more precise and concrete verification of performance and operations are needed. In order to do this, hardware testbed may be developed. but software simulators can provide more flexible and cost effective simulation results. These simulators should provide the essential function handling all kinds of error features experienced upon propagation of the GNSS signal. In this paper, we present a design and implementation results of a window-based simulator applying the modeling of various error features for several GNSS.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.1
• /
• pp.50-55
• /
• 2021

Multi-path system is a system in which utilizes various networks simultaneously. It is expected that multi-path system can enhance communication speed, reliability, security of network. In this paper, we focus on path selection in multi-path system. To select optimal path, we propose deep reinforcement learning algorithm which is rewarded by the round-trip-time (RTT) of each networks. Unlike multi-armed bandit model, deep Q learning is applied to consider rapidly changing situations. Due to the delay of RTT data, we also suggest compensation algorithm of the delayed reward. Moreover, we implement testbed learning server to evaluate the performance of proposed algorithm. The learning server contains distributed database and tensorflow module to efficiently operate deep learning algorithm. By means of simulation, we showed that the proposed algorithm has better performance than lowest RTT about 20%.

• Journal of the Korea Convergence Society
• /
• v.8 no.7
• /
• pp.23-28
• /
• 2017

For manufacturing industry to achieve efficient manufacturing process, improving a company's productivity and reducing cost is a required task of the current manufacturing companies. For design of efficient manufacturing process and improvement of productivity, efficient manufacturing process method is studied through removal of unnecessary elements analyzing motions and using test-bed linkage system based on virtual reality. When building process line after verifying optimization through virtual process arrangement simulation in advance, it is available to save additional cost for process modification or supplement to result in practical effects of improving a company's manufacturing competition. Reducing design period, improving equipment, making automation, realizing ergonomics, and improving process through this study, it will be available to achieve improvement of productivity, enhancement of quality, cost reduction as well as employees' satisfaction for safety and health.

• Journal of the Korean Society for Railway
• /
• v.16 no.6
• /
• pp.528-533
• /
• 2013

To improve the efficiency and safety of railway systems, the train control system has considerably evolved from the ground-equipment-based control system (e.g. track circuit, interlocking system, etc.) into the on-board-equipment-based control system. In addition, this train control system enables the rolling stock to intelligently control the trackside facilities by introducing information and communication technologies (ICT). Accordingly, since the ICT-based train control system simplifies the railway system (i.e. the heavy ground-equipment can be removed), an efficient and cost-effective railway system can be realized. In this paper, we perform a feasibility test of the ICT-based train control system using a simulation. To this end, we implement a test-bed consisting of prototype machines of on-board/ground equipment and introduce an integrated operation scenario for the train control. The simulation results satisfy all the requirements of train operation according to the scenario and show the effectiveness of the proposed train control system.