• 대한안전경영과학회지
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• 제15권4호
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• pp.63-72
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• 2013

Recent trends in rail industry can be characterized by the multifunctionality and very high-speed modes of operations. In particular, the adoption of the unmaned or operatorless operations has been getting increased attention in which case ensuring systems safety is crucial. On the other hand, according to the result of analyzing rail accidents, the human/operator errors have turned out to be one of the key causes of the accidents. Therefore, the effort of improving the work environment of locomotive cabs is quite necessary in order to decrease the accidents. The objective of this paper is studying on how to incorporate the factors related to the train operators in the design of the locomotive cabs and also on how to evaluate the design results obtained, which is subsequently reflected in the generation of the test and evaluation procedure. The approach taken is based on systems engineering, yielding the procedure document as a result. The results obtained in the paper can be useful in confirming the design of locomotive cabs utilizing the domestic human/operator measure. Also, the way of achieving the objectives can be utilized to cover the expanded rail systems development with appropriate design activities added.

• 소성∙가공
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• 제19권1호
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• pp.17-24
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• 2010

A stretch forming method has been widely used in sheet metal forming process. Especially, this process has been adopted in aircraft and high-speed train industries for skin structure forming having a variety of curvature. Until now, solid dies, which are designed with respect to the specific shapes and manufactured as a single piece, have been usually applied to stretch forming process. Therefore, a great number of solid dies has to be developed according to the shapes of the curved skin structure. Accordingly, a flexible die is proposed in this study. It replaces the conventional solid dies with a set of height adjustable punch array. A usefulness of the flexible die is verified through a formability comparison with the solid die using finite element method considering an elastic recovery and the stretch forming apparatus with the flexible die is developed.

• 대한기계학회논문집A
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• 제31권7호
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• pp.756-763
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• 2007

The majority of catastrophic wheel failures are caused by surface opening fatigue cracks either in the wheel tread or wheel flange areas. The inclined cracks at railway wheel tread are initiated and the cracks are caused by wheel damage-spatting after 60,000 km running. Because the failured railway wheel is reprofiled before regular wheel reprofiling, the maintenance cost for the railway wheel is increased. Therefore, it is necessary to analyze the mechanism for initiation of crack. In the present paper, the combined effect on railway wheels of a periodically varying contact pressure and an intermittent thermal braking loading is investigated. To analyze damage cause for railway wheels, the measurements for replication of wheel surface and the effect of braking application in field test are carried out. The result shows that the damages in railway wheel tread are due to combination of thermal loading and ratcheting.

• 비파괴검사학회지
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• 제31권2호
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• pp.118-126
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• 2011

초음파가진 열화상시험 중 가진 방법이 시편에 가진된 진동의 시스템 응답 특성에 미치는 영향에 대하여 연구하였다. 복잡한 현상을 가진 터빈 블레이드 시편에 가진된 진동의 특성을 분석하기 위하여 고출력 가진이 가능한 초음파 혼이 사용되었다. 초음파 혼에 입력되는 신호의 특성이 가진된 진동의 특성에 미치는 영향에 대하여 연구하였고 블레이드를 클램프에 고정한 후 가진기와 클램프를 연결하는 방법이 진동신호에 미치는 영향에 대해서도 연구하였다. 연구 결과를 통하여 첩(chirp) 입력선호와 볼트를 사용하여 클램프와 혼을 연결하는 방법을 가진 방법으로 제안하였다. 이러한 가진 방법은 다양한 종류의 터빈 블레이드 뿐만 아니라 다른 기계부품들의 시험에 적용될 수 있다.

• 한국전기전자재료학회논문지
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• 제22권12호
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• pp.1084-1088
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• 2009

The measurement of dynamic stagger in electric railways is one of the key test parameters to increase speed and maintain safety in electric railways. This paper is introduces a non-contact optical-based measuring instrument of a catenary system in electric railways. The instrument is implemented by utilizing a CCD (Charge Coupled Device) camera installed on the roof of a vehicle for vision acquisition and image processing techniques including the Canny edge detector and the Hough transform to detect contact wires and calculate dynamic stagger. To check the validity of our approach for the intended application, we measured stagger of a overhead wire of a Korea Tilting Train (TTX). The non-contact optical-based measurement system proposed in this paper performs real-time stagger measurement of an activated high-voltage contact wire. By results of this paper, the instrument should be applied to assess performance and reliability of newly developed electric railway vehicles.

• 정보처리학회논문지C
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• 제18C권1호
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• pp.45-50
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• 2011

최근 무선 통신의 발달과 무선 접속 기기의 등장으로 인하여 언제, 어디서든 인터넷을 접속하여 다양한 응용 프로그램을 사용할 수 있게 되었다. 특히, 차량 네트워크의 발달로 이동 중인 차량에서도 인터넷 접속이 가능하게 되었다. 또한, 차량 네트워크와 관련된 다양한 연구들이 활발히 진행되고 있다. 본 논문에서는 실제로 쓰이는 다양한 차량 네트워크의 구조를 살펴보고, 각 구조에서 차량 내에서의 Wi-Fi와 외부의 네트워크를 종합적으로 고려하여 성능 측정을 하였다. 성능 측정 결과를 통해서 현재 사용되고 있는 차량 네트워크의 유용성을 판단하였다.

• 전기학회논문지
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• 제64권6호
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• pp.948-953
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• 2015

In this paper, we studied the environmental requirements for the railway transponder system. The transponder system is comprised of a reader installed beneath the train, a tag installed on the track, and a portable programmer. Among them, the transponder tag should be designed to withstand harsh environments, such as wide operating temperature range, mechanical shock and vibration, etc. To validate stable and reliable service under railway conditions, we carried out environmental test for transponder tag. We then installed the tags on the Honam high-speed test line.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.1-14
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• 2013

In this paper, a finite element analysis technique of rolling stock models for collision-induced derailments was suggested using rolling contacts for wheel-rail interaction. The collision-induced derailments of rolling stock can be categorized into two patterns of wheel-climb and wheel-lift according to the friction direction between wheel flange and rail. The wheel-climb derailment types are classified as Climb-up, Climb/roll-over and Roll-over-C types, and the wheel-lift derailment types as Slip-up, Slip/roll-over and Roll-over-L types. To verify the rolling contact simulations for wheel-rail interaction, dynamic simulations of a single wheelset using Recurdyn of Functionbay and Ls-Dyna of LSTC were performed and compared for the 6-typical derailments. The collision-induced derailment simulation of the finite element model of KHST (Korean High Speed Train) was conducted and verified using the theoretical predictions of a simplified wheel-set model proposed for each derailment type.

• 대한의용생체공학회:의공학회지
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• 제26권2호
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• pp.111-116
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• 2005

This study was designed to apply the stimulation system developed in our laboratory to investigate how the stimulation conditions affect the muscle contractile characteristics in the isometric condition as well as during the FES standing/walking. Four paraplegic and ten healthy subjects participated in this study, and their knee extensors were voluntary contracted or electrically stimulated to measure the muscle force and the fatigue index for different waveforms of the pulse train. We also investigated different combinations of the electrode positions during standing/walking. It was confirmed that continuous and high-frequency stimulation causes faster fatigue than intermittent and low-frequency stimulation. Fatigue resistance was higher around the optimal muscle length than at a stretched position in healthy subjects, whereas the opposite was observed in paralyzed subjects. The paired t-test results with the level of significance at 0.01 indicated that the sinusoidal waveform generated the largest torque among the four typical waveforms. Although statistically not very significant, the sinusoidal waveform also generated, in general, the highest fatigue resistance at an intensity level below the supramaximal stimulation. One of the paraplegic subject who participated in the standing/walking program can now stand up for 1 minute and 50 seconds with the knee extensors, and walk for about 5 minutes at the speed of 12m/sec.

• 전기학회논문지
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• 제67권1호
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• pp.137-141
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• 2018

The voltage drop is important in electric railway for feeding a huge power of train on fixed feeding area. Nowadays it is tried to operate a high speed trains on conventional lines and there is problem on the voltage drop too. It is simulated on the conditions increased the turn ratio of trolley, installed autotransformer neutral line with variable taps. In result, it is compensated the voltage drop between ATs and better on last AT, not on the position of AT. And it is decreased a return current and neutral current of AT because of unbalance between trolley and feeder. It should be studied faster and more controllable the solid state switchs instead of the mechanical one in order to utilize this system.