• Title/Summary/Keyword: moving trains

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Development of Satellite and Terrestrial Convergence Technology for Internet Services on High-Speed Trains (Service Scenarios) (고속열차대상의 위성인터넷 서비스 제공을 위한 위성무선연동 기술(서비스 시나리오 관점))

  • Shin, Min-Su;Chang, Dae-Ig;Lee, Ho-Jin
    • 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.

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Performance Analysis of High-Speed 5G MIMO System in mmWave Band (mmWave대역에서 고속 이동상태 5G MIMO 시스템 성능 분석)

  • Lee, Byung-Jin;Ju, Sang-Lim;Kim, Nam-il;Kim, Kyung-Seok
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.18 no.5
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    • pp.103-109
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    • 2018
  • One of the 5G goals is provide to high data rates for users moving at high speeds, such as trains. High mobility scenarios such as high speed train (HST) scenarios are expected to be typical scenarios for fifth generation communication systems. As the HST develops rapidly, it is necessary to transmit wireless communication data to train passengers, and the communication speed required by users is gradually increasing. HST users require high network capacity and stable communication services regardless of the location or speed of the HST communication system. Therefore, a transmission frame is constructed for the 5G mobile communication system in the mm band to be used for the fifth generation mobile communication, the HST communication system is implemented, and the performance of the wideband non-stationary MIMO HST channel is analyzed in the HST scenario.

Measures for the safety of an electric car in case(Seoul metro) gives up the subway operation (도시철도(서울메트로) 영업운전을 포기할 경우 안전대책방안)

  • Jang, Young-Gil;Yi, Gye-Jean;Yoon, Sung-Woo
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1852-1857
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    • 2007
  • Since the introduction of the subway, remarkable progress has been made so as to be able to produce a Korean standard electric car, but it is rather regretful that an engineer who is not aware of laws on a railroad or involved in a railroad designed a electric car. In the future, the electric cars with up-to-date technology must be introduced, but there are many difficulties in such introduction. For example, the operation of simultaneously moving and running scores of subway trains must comply with Regulation on Railroad Train Operation, so, close examination of these problems is required. The existing electric car, as does a motorcar, varies a little with makers in the type and characteristics. This paper is intended to discuss about the device and measures for reinforcing a function of Daewoo GEC electric car that was introduced by technical tie-up from England, which accounts for the most ratio in this field

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Study on Video Content Delivery Scheme for Mobile Vehicles (이동 차량을 위한 동영상 콘텐츠 전송 기법에 관한 연구)

  • Kim, Tae-Kook
    • Journal of Internet of Things and Convergence
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    • v.7 no.2
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    • pp.41-45
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    • 2021
  • This paper proposes a video content delivery scheme for vehicles. Today, we spend a lot of time commuting to work in vehicles such as trains and cars. In addition, the number of users who enjoy video content such as YouTube and Netflix in order to appease the boredom in the vehicle is increasing rapidly. Video content requires a larger amount of data usage than text-based content. Hence, the user's mobile communication data usage increases rapidly along with the cost. The proposed video content delivery scheme downloads a lot of video content in advance when the vehicle is in a free Wi-Fi area. In this way, it is possible to play video content in a vehicle at a low cost. It is expected that the proposed scheme can be applied to the Internet of Things(IoT) for moving objects.

An Integrated Processing Method for Image and Sensing Data Based on Location in Mobile Sensor Networks (이동 센서 네트워크에서 위치 기반의 동영상 및 센싱 데이터 통합 처리 방안)

  • Ko, Minjung;Jung, Juyoung;Boo, Junpil;Kim, Dohyun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.8 no.5
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    • pp.65-71
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    • 2008
  • Recently, the research is progressing on the SWE(Sensor Web Enablement) platform of OGC(Open Geospatial Consortium) to provide the sensing data and moving pictures collected in a sensor network through the Internet Web. However, existed research does not deal with moving objects like cars, trains, ships, and person. Therefore, we present a method to deal with integrated sensing data collected by GPS device, sensor network, and image devices. Also, this paper proposes an integrated processing method for image and sensing data based on location in mobile sensor networks. Additionally, according to proposed methods, we design and implement the combine adapter. This combine adapter receives a contexts data, and provides the common interface included parsing, queueing, creating unified message function. We verity the proposed method which deal with the integrated sensing data based on combine adapter efficiently. Therefore, the research is expected to help the development of a various context information service based on location in future.

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A Study on Improving Accuracy of Subway Location Tracking using WiFi Fingerprinting (WiFi 핑거프린트를 이용한 지하철 위치 추적 정확성 향상을 위한 연구)

  • An, Taeki;Ahn, Chihyung;Nam, Myungwoo;Park, Jinhong;Lee, Youngseok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.1
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    • pp.1-8
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    • 2016
  • In this study, an WiFi fingerprinting method based on the k-nn algorithm was applied to improve the accuracy of location tracking of a moving train on a platform and evaluate the performance to minimize the estimation error of location tracking. The data related to the position of the moving train are monitored by the control center for trains and used widely for the safety and comfort of passengers. The train location tracking methods based on WiFi installed by telecom companies were evaluated. In this study, a simulator was developed to consider the environments of two cases; in already installed WiFi devices and new installed WiFi devices. The developed simulator can simulate the localized estimation of the position under a variety of conditions, such as the number of WiFi devices, the area of platform and entry velocity of train. To apply location tracking algorithms, a k-nn algorithm and fuzzy k-nn algorithm were applied selectively according to the underlying condition and also four distance measurement algorithms were applied to compare the error of location tracking. In conclusion, the best method to estimate train location tracking is a combination of the k-nn algorithm and Minkoski distance measurement at a 0.5m grid unit and 8 WiFi AP installed.

A Mobility Management Scheme based on the Mobility Pattern of Mobile Networks (이동 네트워크의 이동 패턴에 기반을 둔 이동성 관리 기법)

  • Yang, Sun-Ok;Kim, Sung-Suk
    • Journal of KIISE:Information Networking
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    • v.35 no.4
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    • pp.345-354
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    • 2008
  • Recently, small-scale mobile network which is composed of many mobile devices in a man becomes popular. Also, Examples of large-scale mobile network can be thought access networks deployed on public transportation such as ships, trains and buses. To provide seamless mobility for mobile nodes in this mobile network, binding update messages must be exchanged frequently. However, it incurs network overhead increasingly and decreases energy efficiency of mobile router. If we try to reduce the number of the messages to cope with the problem, it may happen the security -related problems conversely Thus, mobile router needs a effective algorithm to update location information with low cost and to cover security problems. In this paper, mobility management scheme based on mobile router's mobility pattern is proposed. Whenever each mobile router leaves a visiting network, it records related information as moving log. And then it periodically computes mean resident time for all visited network, and saves them in the profile. If each mobile router moves into the visited network hereafter, the number of binding update messages can be reduced since current resident time may be expected based on the profile. At this time, of course, security problems can happen. The problems, however, are solved using key credit, which just sends some keys once. Through extensive experiments, bandwidth usages are measured to compare binding update messages in proposed scheme with that in existing scheme. From the results, we can reduce about 65% of mobility-management-related messages especially when mobile router stays more than 50 minutes in a network. Namely, the proposed scheme improves network usage and energy usage of mobile router by decreasing the number of messages and authorization procedure.

Simulation of Noise and Vibration around the Improved Turnout System (개량분기기 인근의 소음진동 시뮬레이션)

  • Eum, Ki-Young;Um, Ju-Hwan;Lee, Chin-Hyung
    • Journal of the Korea Society for Simulation
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    • v.15 no.4
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    • pp.119-128
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    • 2006
  • A turnout system which permits trains to pass from one track to another is a combination of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 200km/h, at conventional lines by the year of 2010. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefore, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, simulation of noise and vibration around the improved turnout system was performed in order to predict the generation level of noise and vibration due to passing of the tilting train through the turnout system.

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Development of Wireless Smart Sensing Framework for Structural Health Monitoring of High-speed Railway Bridges (고속 철도 교량의 구조 건전성 모니터링을 위한 스마트 무선 센서 프레임워크 개발)

  • Kim, Eunju;Park, Jong-Woong;Sim, Sung-Han
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.5
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    • pp.1-9
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    • 2016
  • Railroad bridges account for 25% of the entire high-speed rail network. Railway bridges are subject to gradual structural degradation or fatigue accumulation due to consistent and repeating excitation by fast moving trains. Wireless sensing technology has opened up a new avenue for bridge health monitoring owing to its low-cost, high fidelity, and multiple sensing capability. On the other hand, measuring the transient response during train passage is quite challenging that the current wireless sensor system cannot be applied due to the intrinsic time delay of the sensor network. Therefore, this paper presents a framework for monitoring such transient responses with wireless sensing systems using 1) real-time excessive vibration monitoring through ultra-low-power MEMS accelerometers, and 2) post-event time synchronization scheme. The ultra-low power accelerometer continuously monitors the vibration and trigger network when excessive vibrations are detected. The entire network of wireless smart sensors starts sensing through triggering and the post-event time synchronization is conducted to compensate for the time error on the measured responses. The results of this study highlight the potential of detecting the impact load and triggering the entire network, as well as the effectiveness of the post-event time synchronized scheme for compensating for the time error. A numerical and experimental study was carried out to validate the proposed sensing hardware and time synchronization method.

Can We Hear the Shape of a Noise Source\ulcorner (소음원의 모양을 들어서 상상할 수 있을까\ulcorner)

  • Kim, Yang-Hann
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.7
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    • pp.586-603
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    • 2004
  • One of the subtle problems that make noise control difficult for engineers is “the invisibility of noise or sound.” The visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical or numerical means to visualize the sound field have been attempted and as a result, a great deal of progress has been accomplished, for example in the field of visualization of turbulent noise. However, most of the numerical methods are not quite ready to be applied practically to noise control issues. In the meantime, fast progress has made it possible instrumentally by using multiple microphones and fast signal processing systems, although these systems are not perfect but are useful. The state of the art system is recently available but still has many problematic issues : for example, how we can implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently it is often difficult to determine the origin of the noise and the spatial shape of noise, as highlighted in the title. The first part of this paper introduces a brief history, which is associated with “sound visualization,” from Leonardo da Vinci's famous drawing on vortex street (Fig. 1) to modern acoustic holography and what has been accomplished by a line or surface array. The second part introduces the difficulties and the recent studies. These include de-Dopplerization and do-reverberation methods. The former is essential for visualizing a moving noise source, such as cars or trains. The latter relates to what produces noise in a room or closed space. Another mar issue associated this sound/noise visualization is whether or not Ivecan distinguish mutual dependence of noise in space : for example, we are asked to answer the question, “Can we see two birds singing or one bird with two beaks?"