• Journal of the Korean Society for Railway
• /
• v.15 no.5
• /
• pp.454-458
• /
• 2012

The CBTC(Communication based Train Control) and WPAN(Wireless Personal Area Network) systems employed on 2.4GHz ISM band wireless networks provide complementary service within the same environment. Coexistence between the networks will be impaired if the mutual packets are uncertainty associated the timing or gaussian distance. This paper analyzes the impact of the mutual interference and proposed method to minimize the effect of the WPAN system signals on CBTC system. The performance analysis is illustrated by examining the symbol error rate versus signal to noise interference ratio in terms of carrier frequency offset. The method contributes to reduce the symbol error rate drastically. However it can't be a fundamental solution for the impact on the interference problem. It may be needed for railway only frequency after checking the problems of the current railway frequency.

• Journal of the Korea Convergence Society
• /
• v.11 no.3
• /
• pp.171-179
• /
• 2020

Media technologies that have made the hyper-connected age change the way people use communication text. Ads texts actively used by companies are storytelling and storydoing. These two advertising texts are very effective in inducing people's emotions and forming participatory behavior. People's thinking tendency also influence persuasion. The results of this study are as follows according to the type of ads text and the thinking tendency of consumers. Consumers' attitudes toward ads turned out to be more positive in synthetic thinking. In analytical thinking, the storytelling ads texts induced more favorable responses. On the other hand, in comprehensive thinking, the story doing text was effective. The same result was found in the perception of premium value, willingness to pay premium price, and repurchase intention.

• Journal of the Society of Disaster Information
• /
• v.13 no.4
• /
• pp.422-441
• /
• 2017

Notifying emergency evacuation methods, accurate disaster location and evacuation route guidance can be very active alternatives to quickly minimize evacuation and casualties in disaster situation in the development of subway disaster prevention detection system that detects the disaster signs at the subway station early on the basis of Internet of things and leads passengers to evacuate. It's not easy to ensure perfect functioning of fire fighting facilities and equipments due to underground space structure with narrow exits. Therefore, we developed disaster provision EL Display integrated board that can induce the most efficient evacuation and the field experiment was conducted to examine the practical application in this study. Especially the applicability was verified by field application test because there is no case in which EL panels are used to evacuate disasters.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.11
• /
• pp.826-833
• /
• 2017

It is important to localize trains precisely for the purpose of controlling them and there have been many studies designed to accomplish this without the need for wayside systems. Since trains run on fixed railway lines, it is possible to search in one direction to localize them. Moreover, it is also possible to know the shape of the line in advance. In the case of high speed trains, their speed and, therefore, their Doppler frequency is relatively high and the railway line is either linear or circular with a large radius. In this study, we utilize these features and propose a train localization method using the Doppler frequency of the signals transmitted from two points (base stations). We derive localization equations for a linear line, circular line, and mixed line (linear plus circular) respectively. Though Doppler radars are usually used to measure speed, the proposed method obtains the location information and the speed successively using the ratio of the doppler frequencies of two signals without knowing the location information or the speed. Computer simulations are performed to show the variation of the estimation error according to the train's location and the measurement error level. The conditions required to obtain the target error level and the increase in the estimation error according to the measurement error are compared between the proposed and conventional methods. The results show the superior performance and robustness of the proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.7
• /
• pp.3220-3226
• /
• 2011

In order to monitor internal risk factors such as fire, terror, etc. on the subway station, the surveillance systems using CCTV and various kinds of sensors have been implemented and recently, introduction of surveillance systems using an advanced IT technology, sensor network technology is tried on several areas. Since 2007, Korean government has made an effort to develop the intelligent surveillance and monitoring system, which can monitor fire, intrusion, passenger congestion, health-state of structure, etc., by using wireless sensor network technology and intelligent video analytic technique. For that purpose, this study carried out field wireless communication environment test on Chungmuro Station of Seoul Metro on the basis of ZigBee that is considered as a representative wireless sensor network before field application of the intelligent integrated surveillance system being developed, arranged and analyzed and ZigBee based wireless communication environment test results on the platform and waiting room of Chungmuro Station on this paper. Results of wireless spectrum analysis on the platform and waiting room showed that there is no radio frequency overlapped with that of ZigBee based sensor network and no frequency interference with adjacent frequencies separated 10MHz or more. As results of wireless data transmission test using ZigBee showed that data transmission is influenced by multi-path fading effect from the number and flow rate of passengers on the platform or the waiting room rather than effects from entrance and exit of the train to/from the platform, it should be considered when implementing the intelligent integrated surveillance system on the station.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.5
• /
• pp.301-308
• /
• 2021

It is important to develop a digital SOC (Social Overhead Capital) maintenance system for preemptive maintenance in response to the rapid aging of social infrastructures. Abnormal signals induced from structures can be detected quickly and optimal decisions can be made promptly using IoT sensors deployed on the structures. In this study, a digital SOC monitoring system incorporating a multimetric IoT sensor was developed for long-term monitoring, for use in cloud-computing server for automated and powerful data analysis, and for establishing databases to perform : (1) multimetric sensing, (2) long-term operation, and (3) LTE-based direct communication. The developed sensor had three axes of acceleration, and five axes of strain sensing channels for multimetric sensing, and had an event-driven power management system that activated the sensors only when vibration exceeded a predetermined limit, or the timer was triggered. The power management system could reduce power consumption, and an additional solar panel charging could enable long-term operation. Data from the sensors were transmitted to the server in real-time via low-power LTE-CAT M1 communication, which does not require an additional gateway device. Furthermore, the cloud server was developed to receive multi-variable data from the sensor, and perform a displacement fusion algorithm to obtain reference-free structural displacement for ambient structural assessment. The proposed digital SOC system was experimentally validated on a steel railroad and concrete girder bridge.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.8
• /
• pp.5513-5521
• /
• 2015

There is an operational efficiency problem about wayside equipment applied to the domestic low-density branch as the equipment has been installed and operated similarly in the mainline. On-board oriented train control system, which has been developed for train safety and operation efficiency, ensures safe train operation without expensive ground control signal devices. Such system consists of on-board control system, wayside control system, and local control system. In this paper, the details of tests such as suitability test, communication test, and interface test are described by installing the on-board control system and wayside control system in field. Installation tests include checking power, voltage, cable connection, LED status, etc. Field applicability of the developed system is also verified through the dynamic operation tests with diverse scenarios, which are performed on the virtual line similar to the real environment including switch machine and level crossing gate. Dynamic operation tests were conducted for total 7 scenarios, and several tests were repeated for each scenario. The elapsed time for each operation was computed by analyzing main process log, and we could check that each operation was accomplished within several seconds. Furthermore, the developed system was verified through field test with an accredited institute, and testing certificates were issued.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.4
• /
• pp.47-53
• /
• 2011

The Electric Multiple Unit (EMU) has many types of door system such as sliding door, plug door etc.al. according to customer's requirements. The sliding door is widely used in Korea but has weak point in the noise problem. In the low operation speed, the noise coming from outer side of the EMU is not an important factor. As the speed is higher than before, noise is increased and make a problem. The main cause of noise is the imperfect air tightness in the EMU. The plug door system has advantages for the noise reduction characteristic in the high speed area. We have been developing electric plug-in door. The door is controlled by Door Control Unit(DCU) following the order of Automatic Train Protection (ATP) that is a kind of train signalling system. DCU has to simultaneously open and close the doors and the operation of it is related to the passengers safety. So DCU is a safety device that is important to reliability and safety. DCU is composed of several devices of control, motor driving, Input/Output, communication and power. In this paper, we will describe the functions, characteristic, requirement, subsystem and test results of DCU used for the electric plug-in door.

• Asia pacific journal of information systems
• /
• v.20 no.1
• /
• pp.127-140
• /
• 2010

The benefit that a consumer derives from the use of a good often depends on the number of other consumers purchasing the same goods or other compatible items. This property, which is known as network externality, is significant in many IT related industries. Over the past few decades, network externalities have been recognized in the context of physical networks such as the telephone and railroad industries. Today, as many products are provided as a form of system that consists of compatible components, the appreciation of network externality is becoming increasingly important. Network externalities have been extensively studied among economists who have been seeking to explain new phenomena resulting from rapid advancements in ICT (Information and Communication Technology). As a result of these efforts, a new body of theories for 'New Economy' has been proposed. The theoretical bottom-line argument of such theories is that technologies subject to network effects exhibit multiple equilibriums and will finally lock into a monopoly with one standard cornering the entire market. They emphasize that such "tippiness" is a typical characteristic in such networked markets, describing that multiple incompatible technologies rarely coexist and that the switch to a single, leading standard occurs suddenly. Moreover, it is argued that this standardization process is path dependent, and the ultimate outcome is unpredictable. With incomplete information about other actors' preferences, there can be excess inertia, as consumers only moderately favor the change, and hence are themselves insufficiently motivated to start the bandwagon rolling, but would get on it once it did start to roll. This startup problem can prevent the adoption of any standard at all, even if it is preferred by everyone. Conversely, excess momentum is another possible outcome, for example, if a sponsoring firm uses low prices during early periods of diffusion. The aim of this paper is to analyze the dynamics of the adoption process in markets exhibiting network effects by focusing on two factors; switching and agent heterogeneity. Switching is an important factor that should be considered in analyzing the adoption process. An agent's switching invokes switching by other adopters, which brings about a positive feedback process that can significantly complicate the adoption process. Agent heterogeneity also plays a important role in shaping the early development of the adoption process, which has a significant impact on the later development of the process. The effects of these two factors are analyzed by developing an agent-based simulation model. ABM is a computer-based simulation methodology that can offer many advantages over traditional analytical approaches. The model is designed such that agents have diverse preferences regarding technology and are allowed to switch their previous choice. The simulation results showed that the adoption processes in a market exhibiting networks effects are significantly affected by the distribution of agents and the occurrence of switching. In particular, it is found that both weak heterogeneity and strong network effects cause agents to start to switch early and this plays a role of expediting the emergence of 'lock-in.' When network effects are strong, agents are easily affected by changes in early market shares. This causes agents to switch earlier and in turn speeds up the market's tipping. The same effect is found in the case of highly homogeneous agents. When agents are highly homogeneous, the market starts to tip toward one technology rapidly, and its choice is not always consistent with the populations' initial inclination. Increased volatility and faster lock-in increase the possibility that the market will reach an unexpected outcome. The primary contribution of this study is the elucidation of the role of parameters characterizing the market in the development of the lock-in process, and identification of conditions where such unexpected outcomes happen.