• Title/Summary/Keyword: 주파수 보정곡선

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Analysis of the Frequency Weighting Curve for the Evaluation of Ride Comfort (승차감 평가를 위한 주파수 보정곡선의 분석)

  • Kim, Y.G.;Park, C.K.;Kim, S.W.;Kim, K.H.;Paik, J.S.
    • Journal of the Korean Society for Railway
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    • v.13 no.6
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    • pp.552-558
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    • 2010
  • Ride comfort of railway vehicles is affected by many factors, such as vibration, noise, smell, temperature, visual stimuli, humidity and a seat design. In general, vibration, which originates from vehicle motion, is considered as the primary concern. In evaluating the ride comfort, relationship between passenger's feeling and vibration characteristics is very important because human feeling is dependent on frequency spectrum of vibration. Therefore, the weighing functions in frequency domain are used to evaluate the ride comfort of railway vehicles. In the present paper, we have analyzed the characteristics of the frequency weighting curves defined in many standards and reviewed the effect resulting from their difference on the ride comfort.

Evaluation of Ride Comfort in Time Domain by Using z-Transform (z변환을 이용한 시간영역에서의 승차감 평가)

  • Kim, Young-Guk;Kim, Seog-Won;Park, Chan-Kyoung;Kim, Sang-Soo;Kim, Ki-Hwan
    • Journal of the Korean Society for Railway
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    • v.14 no.6
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    • pp.495-500
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    • 2011
  • In evaluating the ride comfort of railway vehicles, relationship between passenger's feeling and vibration characteristics is very important because human feeling is dependent on frequency spectrum of vibration. Therefore, the weighing curves in frequency domain are used to evaluate the ride comfort of railway vehicles. These curves have been defined in the Laplace transfer functions. It is necessary to convert the Laplace weighing function to the z weighing function in order to obtain the rms value in the time domain. In the present paper, we have applied Tustin's approximation to transform the Laplace weighing function to the z weighing and validated this method by reviewing the various cases.

Analysis of Correlation with Evaluation Methods of Ride Comfort for the Railway (철도 승차감 평가방법의 상호관계 분석)

  • 김영국;박찬경;이은호;박태원;배대성
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.3
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    • pp.204-212
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    • 2002
  • The ride comfort is one of the important dynamic performances of railway vehicle and is affected by the various factors, such as vibration, sound, temperature, humidity, etc. In general, vibration is known to be a major effect of rode comfort. There are many studies on the evaluation methods of ride comfort in the railway vehicle vibration. Each of the evaluation methods suggested by Spelling and in the standards recommends a different evaluation method and guidance. So users must review whether they can apply it to their railway system or not. In this study, we have suggested the relationship between several evaluation methods using the statistical vibration model based on the experimental data.

A Study on the Car Audio Sound Qualify Enhancement under Vehicle Noise (차량 주행소음을 고려한 자동차 오디오 음질 개선법 연구)

  • Park Seok Tae;Kim Kyung Hwan;Lee Jong Kyu
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.274-277
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    • 1999
  • 자동차 오디오는 차량의 상품성에 큰 영향을 미치고 있다. 고급 차량일수륵 또한 젊은 층일수록 차량 구매시 선택의 기준이 되기도 한다 그러나 자동차 오디오는 크게 두가지 면에서 가정용 오디오와 차이가 있다. 첫번째는 청취공간이 매우 헙소하다는 것이고 둘째로는 주행시 차량소음이 차 실내로 유입되어 오디오 음질에 영향을 미친다. 차 실내는 즘은 공간 음향폭성으로 인한 음향 dip 현상이 발생하며 이는 오디오 음질의 왜곡을 가져오므로 이를 개선하기 위해서는 라우드스피커 최적배치 뿐 아니라 주행소음에 대한 시험 및 분석을 하여 오디오 음질에 영향을 주는 주파수 밴드를 파악하여야 한다 본 논문에서는 오디오 음에 차량소음이 섞인 경우에 대하여 차량의 라우드스피커 위치는 변경하지 않고 라우드스피커의 주파수 밴드별 출력을 디지털필터를 이용하여 수정하는 방법으로 음질 개선을 제안하였다. 디지털 필터의 보정치는 차량 주행소음 특성과 차 실내 음향특성을 고려하였다. 차량소음을 섞은 주파수 옥타브 밴드 분석법을 이용한 객관적인 분석과 감성적 분석법인 NCB곡선으로 차량소음을 분식하여 디지털 필터 보정치를 구하는데 사용하였다. 제안한 9가지 디지털 필터를 이용하여 차량소음과 음악을 합성하였고 이중에서 좋은 음질에 대한 판정을 하기 위해 Scheffe가 제안한 7점 주관 평가법을 사용하여 64명이 내린 주관평가를 수행하였다.

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Optical Design for Satellite Camera with Online Optical Compensation Movements (온라인 광학보정장치를 적용한 위성카메라의 광학설계)

  • Jo, Jeong-Bin;Hwang, Jai-Hyuk;Bae, Jae-Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.3
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    • pp.265-271
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    • 2015
  • In this study, optical design for small satellite camera equipped with online optical compensation movements has been conducted. Satellite camera equipped with compensation movements at M2 mirror and focal plane can guarantee the MTF performance through the focal plane image stabilization and the on-orbit optical alignment. The designed optical system is schmidt-cassegrain type that has M1 mirror of a diameter 200mm, GSD 3.8m at an altitude of 700km, and 50 % MTF performance. The performance of the designed optical system has been analyzed through the method of ray aberration curve, spot diagram, and MTF. It has been found by the optical performance analysis that the designed optical system satisfies the optical requirements of satellite camera equipped with online optical compensation movements.

A study on the Ride Comfort for High Speed Train on the High Speed Line/Conventional Line (고속선/기존선 연계운행에 대한 고속철도 차량의 승차감에 관한 연구)

  • 김영국;김석원;박찬경;김기환
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.206-211
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    • 2004
  • Recently, the ride comfort problem becomes increasingly important because of today's needs for train speedup. The concept of ride comfort is equivocal. Generally, it is defined as the body vibration. The commercial high-speed train must be run the compound line in Korea which is composed of high-speed line and conventional line. In this paper, the ride comfort has been reviewed by the various experimental methods when the high-speed train is operated on both lines. The results show that the high-speed train has no problems from the viewpoint of the comfort ride during the operation on both lines.

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Evaluation of human vibration of high speed train using ISO 2631 (ISO 2631에 따른 국내 고속철도차량 인체진동 평가)

  • Kim, Ji Man;Park, Jin Han;Ahn, Se Jin;Jeong, Weui Bong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.131-133
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    • 2014
  • Vibration exposure of the KTX and ITX-saemaeulho on the Gyung-Bu line was evaluated and compared in terms of human health based on ISO 2631. RMS value of KTX was calculated as much lower than ITX-saemaeulho in all travel sections. When VDV result of the two trains drived return travel from Seoul to Busan in single day is compared on the health guidance caution zone of ISO 2631, vibration exposure of KTX is safer than ITX-saemaeulho which is marginally under the caution line.

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Analysis of Ride Comfort for Korean High Speed Train through On-line Test (시운전 시험을 통한 한국형 고속전철에 대한 승차감의 분석)

  • 김영국;김석원;박찬경
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.549-554
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    • 2003
  • Recently, the ride comfort problem becomes increasingly important because of today's needs for train speedup. The concept of ride comfort is equivocal. Generally, it is defined as the body vibration. The prototype of Korean high speed train (KHST), composed of two power cars, two motorized cars and three trailer cars, has been designed, fabricated and tested by the domestic researchers. In this paper, the ride comfort has been reviewed by the experimental method. The on-line test of KHST has been carried out up to 260km/h in the KTX line and proved that KHST has no problems from the viewpoint of the comfort ride at this speed. And the ride index lot KHST has been predicted at 300km/h and 350km/h by fitting curve.

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Travel Time Calculation Using Mono-Chromatic Oneway Wave Equation (단일주파수 일방향파동방정식을 이용한 주시계산)

  • Shin, Chang-Soo;Shin, Sung-Ryul;Kim, Won-Sik;Ko, Seung-Won;Yoo, Hai-Soo
    • Geophysics and Geophysical Exploration
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    • v.3 no.4
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    • pp.119-124
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    • 2000
  • A new fast algorithm for travel time calculation using mono-chromatic one-way wave equation was developed based on the delta function and the logarithms of the single frequency wavefield in the frequency domain. We found an empirical relation between grid spacing and frequency by trial and error method such that we can minimize travel time error. In comparison with other methods, travel time contours obtained by solving eikonal equation and the wave front edge of the snapshot by the finite difference modeling solution agree with our algorithm. Compared to the other two methods, this algorithm computes travel time of directly transmitted wave. We demonstrated our algorithm on migration so that we obtained good section showing good agreement with original model. our results show that this new algorithm is a faster travel time calculation method of the directly transmitted wave for imaging the subsurface and the transmission tomography.

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Evaluation of Human Exposure to Vibration on Domestic High-speed Train using ISO 2631-1 (ISO 2631-1을 이용한 국내 고속철도차량의 인체진동 노출량 평가)

  • Kim, Ji Man;Park, Jin Han;Ahn, Se Jin;Jeong, Weui Bong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.4
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    • pp.266-274
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    • 2015
  • Vibration exposure of domestic high speed trains(KTX and ITX-saemaeulho) to passenger traveling on the Gyung-Bu line was measured to evaluate health effect which is based on ISO 2631-1. The vibration exposure was compared with the frequency weighted root mean square(r.m.s.) and vibration dose value(VDV) of the two trains’ vibration. It is concluded that vibration exposure of the two train during round trip of Busan-Seoul in single day is evaluated to be safe for the passenger’s health according to the health guidance caution defined on ISO 2631-1. Futhermore KTX’s vibration exposure is found to be significantly lower than ITX-saemaeulho thanks to lower vibration magnitude as well as shorter trip time.