• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.305-306
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• 2013

• 한국안전학회지
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• 제20권1호
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• pp.30-35
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• 2005

This study proposes construction of through transmission for weld defects detection of rail weld zone from ultrasonic signals. For these purposes, the ultrasonic signals for defects(porosity and crack) of weld zone in rails are acquired in the type of time series data and echo strength. 6 lines in the distance amplitude characteristics curve(DACC) indicated damage evaluation standard of weld zone in rails. The acquired ultrasonic signals agree flirty well with the mesured results of reference block and sensitivity block(defect location beam propagation distance, echo strength, etc). The proposed construction of through transmission in this study can be used for weld defects detection of rail weld zone.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.79-83
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• 2010

Recently, the flat wiper which is one piece wiper and subjected to a pressing force at a single center point is gaining wide applications on automotive windshields. However, nonuniform reactive pressure distributions takes place, so that wiping is not completed at such locations. The wiping performance of the flat wiper is best when a wiper and a curved windshield have perfect contact without gaps under the specified pressing force of 13 ~ 15 gf/cm. Therefore, it is necessary that the realistic curvature equation of a wiper spring-rail should be obtained. Finite element analysis, CATIA script-macro function, and the least square method were utilized to find out the curvature of a spring-rail for a perfect contact with a windshield under a specified concentrated load. The curvature equation became the third order polynomial.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.415-422
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• 2000

The Seoul Subway Line 4 crossing downtown diagonally constructed in February 1980 and opened on October 11, 1983. The line 4 is thus able to link southern and northern parts of Seoul with the downtown as well as with the Seoul outskirts. More than 810,000 people use it everyday. Line 4 was constructed like Line 1,2,3 with ballast track system causing much maintenance cost gradually and espicially much public discontent due to wheel and rail contact noise by railway viaduct with sharp curves. CWR on railway viaduct with sharp curves, 180m$\leq$R$\leq$300m, hasn't been designed and constructed ever in domestic. Therefore in order to reduce noise and vibration caused by interaction between wheel and rail the possibility and the methods of CWR(Continuous Welded Rail) on railway viaduct with sharp curve less than R300 will lead it to the maintenance free system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.442-445
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• 2011

Concrete track on the new railway lines of the existing roads are built on high ground, or less than 400m radius of the sharp curve sectors will occur. sharp curve sectors the rail and wheel friction, stick-slip due to the band of 1,000Hz or squeal noise occurs from the increase in civil complaints about noise is a real situation. In this study, discussed in previous studies, noise measurements for each radius of concrete track and frequency analysis, followed by the radius of the curve in order to investigate vibration characteristics of urban railway sector sharp curve radius less than 400m and 400m ~ 1,000 m further to the point selected track components(rails, sleepers, ballast) according to the vibration measurements and analysis of the frequency characteristics and the results were derived.

• 한국도시철도학회논문집
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• 제6권4호
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• pp.339-350
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• 2018

도시철도에서 지하 터널의 미세먼지는 여러 가지 요인에 의하여 발생하고 있다. 도시철도 미세먼지 발생량을 예측하기 위하여 여러 가지 발생요인 중 레일 마모량 분석에 관한 연구를 수행하였다. S호선 구간(약 45km)에서 1년 6개월 간 레일마모측정장치에서 측정된 레일 마모 데이터를 곡선반경(R)의 변화에 따라 약 170개 구간으로 구분하였으며, 레일 마모 측정값 중에서 직마모량(C0)와 편마모(V0)량을 이용하여 곡선반경에 따른 레일 마모량 관계를 분석하고, 직선구간과 곡선구간에서 각각 구간평균 편 직마모량과 노선평균 편 직마모량을 산출하였다. 레일 마모량과 레일 단면적의 상관관계를 분석하여 단면적에 대한 근사식을 구하고, 레일 C0와 V0의 변화량을 이용하여 레일 마모에 의한 미세먼지 발생량을 산정하였다.

• International Journal of Safety
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• 제10권2호
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• pp.21-26
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• 2011

In 2001, an independent official board was constituted in Japan to investigate aircraft and railway accidents. In the past 10 years, many accidents and serious incidents have been investigated and these official reports were published by the board, on which the author had sat for 9 years as boarding member. In the interim, there were several train disasters which mocked our trust in railways and also many apparent trivial incidents. In recent years, serious incidents, which a door of running rail cars opens suddenly with some trouble, happen 2 or 3 times in a year. For the past 10 years, such incidents have happened 14 times and 13 cases of them were closed by the board mentioned above. In these 13 cases, no one fell off the rail car, so that the death toll was none luckily. In this paper, these 13 serious incidents are picked up among all the reports published by the board and outlined using some tables. Especially, fall accidents of passengers are discussed mainly from the view point of impact force and duration time. Then, the equation of HIC (Head Injury Criteria) and the risk curves in terms of the HIC are dealt with properly.

• 한국정밀공학회지
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• 제25권10호
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• pp.77-83
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• 2008

In terms of saving costs, energy and materials, the weight of cars has been gradually reduced by optimizing design of structure, which also gives us good performance. In compliance with this, it should satisfy the lifetime of cars for 25 years under the operation. The purpose of this study is to evaluate the strength of fatigue using date from strain gauges attached carbody and bogie frame. This dynamic stress can be evaluated using S-N curve based on stress amplitude. Modified S-N curve by CORTON-DOLAN is used for more conservative and substantial evaluation. In addition, !he loadings itself of carbody and bogie frame are considered by calculating the rate of the differences which are occurred between empty car and fuiiy occupied car with passengers. Rainflow cycle counting method is applied to arrange the stress data for the modified S-N curve to predict lifetime of the materials. Conclusively the cumulative damages are not only calculated by Miner's Rule, but the safety factors are also determined by Goodman diagram.

• 한국철도학회논문집
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• 제11권3호
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• pp.317-325
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• 2008

최근 연구결과 레일연마 및 장대레일화로 누적통과톤수에 의한 레일교체기준의 연장이 가능한 것으로 보고되었다. 본 연구에서는 현재 도시철도에서 사용 중인 대표 궤도구조에 대해 실운행 열차하중에 의한 궤도의 동적 응답을 분석하여 현 궤도의 상태평가를 하였으며 궤도의 상태 변화에 따른 레일의 부담력을 검토하였다. 또한, 측정된 응력파형을 Rainflow Count Method를 이용하여 응력히스토그램을 작성하고 등가응력을 상정하여 신규 레일 용접부의 S-N 선도에 적용함으로써 노후레일의 누적피로손상도 및 휨 피로수명을 산정하였다. 최종적으로 본 연구에서는 궤도구조 및 상태를 고려한 레일교체기준의 개정을 제안하고자 하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1320-1326
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• 2011

The maximum speed of high-speed rail is restricted to various factors such as track condition including slope and radius, tunnel and dynamic stability of vehicle. Among the various factors, traction effort and resistance to motion is principal and basic factor. In addition, at high speed over 300km/h, aerodynamic drag amounts up to 80% of resistance to motion, that it can be said that aerodynamic drag is the most important factor to decide the maximum speed of high-speed rail system. This paper deals with a measure to increase the maximum speed of high-speed train by reducing aerodynamic drag. The traction effort curve and resistance to motion curve of existing high-speed train under development has been employed to set up the target of aerodynamic drag reduction to reach up to 500km/h without modification traction system. In addition, the contribution of various sources of aerodynamic drag to total value has been analyzed and the strategy for implementation of aerodynamic drag reduction has been discussed based on the aerodynamic simulation results around the train using computational fluid dynamics.