• Title/Summary/Keyword: Track structure improvement

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Application of Vertical Grid-nesting to the Tropical Cyclone Track and Intensity Forecast

  • Kim, Hyeon-Ju;Cheong, Hyeong-Bin;Lee, Chung-Hui
    • Journal of the Korean earth science society
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    • v.40 no.4
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    • pp.382-391
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    • 2019
  • The impact of vertical grid-nesting on the tropical cyclone intensity and track forecast was investigated using the Weather Research and Forecast (WRF) version 3.8 and the initialization method of the Structure Adjustable Balanced Bogus Vortex (SABV). For a better resolution in the central part of the numerical domain, where the tropical cyclone of interest is located, a horizontal and vertical nesting technique was employed. Simulations of the tropical cyclone Sanba (16th in 2012) indicated that the vertical nesting had a weak impact on the cyclone intensity and little impact on the track forecast. Further experiments revealed that the performance of forecast was quite sensitive to the horizontal resolution, which is in agreement with previous studies. The improvement is due to the fact that horizontal resolution can improve forecasts not only on the tropical cyclone-scale but also for large-scale disturbances.

Case of track improvement in the area of redevelopment project surrounding around Seoul Metro Lin.4(R=250m) (서울지하철 4호선 R250m 인접구간 도시개발정비에 따른 궤도방진설계)

  • Kong, Sun-Yong;Kim, Sang-Jin;Yang, Tae-Kyung;Baik, Chan-Ho
    • Proceedings of the KSR Conference
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    • 2010.06a
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    • pp.324-329
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    • 2010
  • The surroundings around subway are becoming more lively for project of CBD (an redevelopment project), however vibrations which are made through passing train cold spread buildings around. The structure-borne noise could be generated at the same time that makes people including developers and th citizens have negative viewpoint on railway. Especially, Seoul Metro 1-4 lines ar built alongside the road nearby houses and business district. That could make plenty of public resentments because of the structure-borne noise. Seoul Metro should make active alternative plans for their future urban environment projects which will be conducted. The case was Railway Facility which were conducted to minimize structure-borne noise from sharp curved track section (4 line, Sinyongsan~Ichon, R 250m). The section is adjacent to house district as near as 6.6m related with pusing international city project, the 4th urban environment project around international building, near Yongsan station. The interval of sleepers would be downsized in half with breaking existing case, and pad stiffness is reduced 4 ton from 10 ton. That makes structure-borne noise minimized because of vibrations are lowered about 19.1-23.0db. The structure above has remained for a year and a half from October, 2008, and had not any trouble to perform excellence with 80million ton rail accumulated tonnage.

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Asymptotic Disturbance Rejection using a Disturbance Observer in the Track-Following Control System of a High-Speed Optical Disk Drive (고배속 광디스크 드라이브 트랙 추종 제어 시스템에서의 외란 관측기를 이용한 점근적 외란 제거)

  • 유정래;문정호;진경복;정명진
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.5
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    • pp.402-410
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    • 2004
  • To obtain a good tracking performance in an optical disk drive servo system, it is essential to attenuate periodic disturbances caused by eccentric rotation of the disk. As an effective control scheme for enhancing disturbance attenuation performance, disturbance observers (DOBs) have been successfully applied to the track-following servo system of optical disk drives. In disk drive systems, the improvement of data transfer rate has been achieved mainly by the increase of disk rotational speed, which leads to the increase of the disturbance frequency. Conventional DOBs are no longer effective in disk drive systems with a high-speed rotation mechanism because the performance of conventional DOBs is severely degraded as the disk rotational frequency increases. This paper proposes a new DOB structure for effective rejection of the disturbance in optical disk drives with a very high rotation speed. Asymptotic disturbance rejection is achieved by adopting a band-pass filter in the DOB structure, which is tuned based on the information on the disturbance frequency. In addition, performance sensitivity of the proposed DOB to changes in disk rotational frequency is analyzed. The effectiveness of the proposed DOB is verified through simulations and experiments using a DVD-ROM drive.

A Program Generating and Managing Track Data for Smart Train Route Control (Smart열차진로제어를 위한 선로데이터 생성.관리프로그램)

  • Yoon, Yong-Ki;Lee, Young-Hoon
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.1741-1745
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    • 2007
  • Even though the existing train route controlling method, using track circuits, ensures the sufficient number of operation, it still has problems such as discordance between train numbers which was planned for operating and train numbers being operated on the track, and allowing only one train entering for one route. To solve those problems, we study and develop the Smart train route controlling system which uses the real-time informations of train positions. This system enables improve the coefficient of utilization in a certain train route controlling section, and the safety level of train route controlling, but we should ensure satisfying reliability of data about tracks operated by trains. In addition, there is a need to protect accidents caused by erroneous information of train position, by reflecting changes of tracks, for example maintenance, improvement, expansion of tracks. In this paper, we proposes and describes a developed program which required to change AutoCAD files to wiring diagrams, to generate them to data of tracks, to identify errors of those data, to construct the structure of necessary resource(s) for sub-systems of a train control system, and to provide simulations of data structure.

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A Study on Safety Standards of a Railway Crossing (철도 건널목 안전기준에 관한 연구)

  • Jeong, Yeon-Jeong;Lee, Seong-Mo;Park, Chang-Ho
    • Journal of Korean Society of Transportation
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    • v.27 no.1
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    • pp.83-95
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    • 2009
  • The railway crossing is very dangerous because the track intersects with the road there. Thus, The laws were designed for safety of the railway crossing and they are classified as to the acts for the road and the railroad. For safety of the railway crossing, there are 'Road/Railroad Crossing Improvement Promotion Act', 'Enforcement Decree of Road/Railroad Crossing Improvement Promotion Act', 'Rules on Construction of Railroad', 'Rules on Safety Standards of Railroad Installations', and 'Enforcement Ordinance of Cable way/Railway Track Act' in the acts for the railroad and there are 'Road Traffic Act', 'Enforcement Ordinance of The Road Traffic Act', 'Ruled on Structure and Facility Standards of The Road', 'Rules on Structure And Facility Standards Of The Rural Road' and 'Rules on Structure and Facility Standards of The Installations for Bicycle' in the acts for the road. Both the acts for the road and the railroad have standards for the structure of the railway crossing. However, they have different standards. Besides, they don't have standards for new facilities which were recently installed for safety of the railway crossing. Therefore, we suggest new standards for safety of the railway crossing.

Performance Improvement of MIMO MC-CDMA system with multibeamforming

  • Kim, Chan Kyu
    • International Journal of Internet, Broadcasting and Communication
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    • v.11 no.2
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    • pp.76-83
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    • 2019
  • In this paper, we propose the beamforming algorithm for the performance improvement of MIMO MC-CDMA system. The proposed multibeamforming of MIMO MC-CDMA structure having the same number of beamformer as the number of transmit antenna is derived by calculating the error signals between the coded pilot symbols and the corresponding received signals from the multiple transmitters of the desired user in the frequency domain, transforming the frequency-domain error signals into time-domain error signals, and updating the weights of the multibeamformer in the time-domain in the direction minimizing the mean squared error (MSE). The proposed approach can track each direction of arrival (DOA) of the signals from multi-antennas of a desired user. The performance improvement is investigated through computer simulation by applying the proposed approach to MIMO MC-CDMA system in a multipath fading channel with multiusers.

Two-dimensional nonconforming finite elements: A state-of-the-art

  • Choi, Chang-Koon;Kim, Sun-Hoon;Park, Young-Myung;Chung, Keun-Young
    • Structural Engineering and Mechanics
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    • v.6 no.1
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    • pp.41-61
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    • 1998
  • A state-of-the-art report on the new finite elements formulated by the addition of nonconforming displacement modes has been presented. The development of a series improved nonconforming finite elements for the analysis of plate and shell structures is described in the first part of this paper. These new plate and shell finite elements are established by the combined use of different improvement schemes such as; the addition of nonconforming modes, the reduced (or selective) integration, and the construction of the substitute shear strain fields. The improvement achieved may be attributable to the fact that the merits of these improvement techniques are merged into the formation of the new elements in a complementary manner. It is shown that the results obtained by the new elements give significantly improved solutions without any serious defects such as; the shear locking, spurious zero energy mode for the linear as well as nonlinear benchmark problems. Recent developments in the transition elements that have a variable number of mid-side nodes and can be effectively used in the adaptive mesh refinement are presented in the second part. Finally, the nonconforming transition flat shell elements with drilling degrees of freedom are also presented.

Applicability Estimation of Ballast Non-exchange-type Quick-hardening Track Using a Layer Separation Pouring Method (층 분리주입을 이용한 도상자갈 무교환방식 급속경화궤도의 적용성 평가)

  • Lee, Il Wha;Jung, Young Ho;Lee, Min Soo
    • Journal of the Korean Society for Railway
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    • v.18 no.6
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    • pp.543-551
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    • 2015
  • Quick-hardening track (QHT) is a construction method which is used to change from old ballast track to concrete track. Sufficient time for construction is important, as the construction should be done during operational breaks at night. Most of the time is spent on exchanging the ballast layer. If it is possible to apply the ballast non-exchange type of quick-hardening track, it would be more effective to reduce the construction time and costs. In this paper, pouring materials with high permeability are suggested and a construction method involving a layer separation pouring process considering the void condition is introduced in order to develop ballast non-exchange type of QHT. The separate pouring method can secure the required strength because optimized materials are poured into the upper layer and the lower layer for each void ratio condition. To ensure this process, a rheology analysis was conducted on the design of the pouring materials according to aggregate size, the aggregate distribution, the void ratio, the void size, the tortuosity and the permeability. A polymer series was used as the pouring material of the lower layer to secure the void filling capacity and for adhesion to the fine-grained layer. In addition, magnesium-phosphate ceramic (MPC) was used as the pouring material of the upper layer to secure the void-filling capacity and for adhesion of the coarse-grained layer. As a result of a mechanics test of the materials, satisfactory performance corresponding to existing quick-hardening track was noted.

Impact Energy Absorbtion Characteristics Review on the Initial Design of TTX Mcp Car front-end Structure (기존선 틸팅차량 Mcp Car 차체 설계초안의 충돌에너지 흡수특성 고찰)

  • Kwon Tae-soo;Jung Hyun-Seung;Koo Jeong-Seo
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.732-737
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    • 2004
  • TTX(Tilting Train Express), which has improved traveling performance on curved track, is being designed in cope with future railway circumstance. Nowadays, in the world, many efforts are focussed on railway safety. Especially, a variety of researches on train crashworthiness have been conducted. As a part of these efforts, some equipments on TTX are designed to reduce fatalities and casualties in crash accidents. This paper introduces impact energy absorbtion characteristics on the initial design of the front end structure. Some comments are made briefly for improvement of initial structural design and future following researches.

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Improvement of a Detecting Algorithm for Geometric Center of Typhoon using Weather Radar Data (레이더 자료를 이용한 기하학적 태풍중심 탐지 기법 개선)

  • Jung, Woomi;Suk, Mi-Kyung;Choi, Youn;Kim, Kwang-Ho
    • Atmosphere
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    • v.30 no.4
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    • pp.347-360
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    • 2020
  • The automatic algorithm optimized for the Korean Peninsula was developed to detect and track the center of typhoon based on a geometrical method using high-resolution retrieved WISSDOM (WInd Syntheses System using DOppler Measurements) wind and reflectivity data. This algorithm analyzes the center of typhoon by detecting the geometric circular structure of the typhoon's eye in radar reflectivity and vorticity 2D field data. For optimizing the algorithm, the main factors of the algorithm were selected and the optimal thresholds were determined through sensitivity experiments for each factor. The center of typhoon was detected for 5 typhoon cases that approached or landed on Korean Peninsula. The performance was verified by comparing and analyzing from the best track of Korea Meteorological Administration (KMA). The detection rate for vorticity use was 15% higher on average than that for reflectivity use. The detection rate for vorticity use was up to 90% for DIANMU case in 2010. The difference between the detected locations and best tracks of KMA was 0.2° on average when using reflectivity and vorticity. After the optimization, the detection rate was improved overall, especially the detection rate more increased when using reflectivity than using vorticity. And the difference of location was reduced to 0.18° on average, increasing the accuracy.