• Title/Summary/Keyword: 압력변동

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Theoretical Study on the Characteristics of Pressure Change of High Speed Train in Tunnels (터널통과시 고속 철도 압력 변동 특성에 관한 이론적 연구)

  • Nam, Seong-Won;Kwon, Hyeok-Bin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.9
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    • pp.1042-1050
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    • 2004
  • Theoretical study has been conducted to clarify pressure characteristics of KTX(Korea Train eXpress) in tunnel. The severe pressure change in tunnel may give rise to the ear-discomfort for passenger and fatigue for car body. The external and internal pressure of rolling stock have been measured by using the running test with atmospheric pressure sensors and portable data acquisition system in high speed train. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. We found that there are similar patterns of external pressure change for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity. And, the patterns of pressure wave in tunnel are classified into eight groups.

Pressure Variation Characteristics at Trapping Region in Oil Hydraulic Piston Pumps (유압 피스톤 펌프의 폐입구간에서 발생하는 압력변동 특성)

  • Kim, Jong-Ki;Jung, Jae-Youn;Rho, Byung-Joon;Song, Kyu-Keun;Oh, Seok-Hyung
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.2071-2075
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    • 2003
  • Pressure variation is one of the major sources on noise emission in the oil hydraulic piston pumps. Therefore, it is necessary to clarify about pressure variation characteristics of the oil hydraulic piston pumps to reduce noise. Pressure variations in a cylinder at trapping region were measured during pump working period with discharge pressures, rotational speeds. The effect of pre-compression of the discharge port with three types valve plates also investigated. It was found that the pressure variation characteristics of oil hydraulic piston pumps deeply related with pre-compression design of the discharge port. Also, it was found that the pressure overshoot at trapping region can reduce by use of pre-compression at the end of the discharge port in valve plate

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Tne Measurements of internal Dynamic Pressure for Development of a High Performance Oil hydraulic Vane Pump(I) (고성능 유압 베인펌프 개발을 위한 내부 변동압력 측정 (I))

  • 정재연;정석훈
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.2
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    • pp.191-199
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    • 1992
  • This paper presents in experimental study of the dynamic internal pressure within an oil hydraulic vane pump. The measurements of the dynamic internal pressures near the vane of a pressure balance type of an oil hydraulic vane pump with intravanes has been made to provide the essential information for the study of the pump dynamics and control, the pump design and the analysis of tribological problems in the sliding components. The influences of the discharge pressure and rotating speed of the vane on the dynamic pressure in four chambers surrounding a vane have been investigated. The results indicate that the surge pressures of the chambers at the instant moment of discharge and closure are affected by the rotating speed. The pressure in the intravane chamber maintains almost constant values, which remarkably effects the pulsating discharge pressure.

Development of a new test facility for the study of pressure transients in tunnel and micro-pressure waves radiated from the tunnel exit on the railroad (철도터널내 압력변동 및 터널 미기압파 저감 시험장치개발에 관한 연구)

  • Kim, Dong-Hyeon;Oh, Il-Geun
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.611-618
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    • 2000
  • The test facility of the 1/60-scale models for the train-tunnel interactions was recently developed to investigate the effects of entry portal shapes, hood shapes and air-shafts for reducing the micro-pressure waves radiating to the surroundings of the tunnel exits by KRRI in Korea. The launching system of train model was chosen as air-gun type. In present test rig, after train model is launched, the blast wave by the driver did not enter to inside of the tunnel model. The train model is guided on the one-wire system from air-gun driver to the brake parts of test facility end. Some cases of the experiments were compared with numerical simulations to prove the test facility.

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A Study on Natural Ventilation Performance by Periodic Outdoor Pressure Fluctuations (주기적인 외부 압력변동에 의한 자연환기성능 연구)

  • Lee, Seung-Yeon;Yom, Chol-Min;Han, Hwa-Taek
    • Proceedings of the SAREK Conference
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    • 2005.11a
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    • pp.27-32
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    • 2005
  • This paper investigates the effects of outdoor pressure fluctuations on natural ventilation through openings of a building envelope. The ventilation airflow rate depends on the magnitude and the period of the pressure fluctuations, the size of the opening compared to the space volume, and the resistance characteristics of the opening. Non-dimensional parameters have been derived, which determine indoor pressure responses due to outdoor pressure fluctuations. The flow regions are categorized into synchronized region, opening resistance region, and transition region depending on the non-dimensional parameters.

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A Study on the Characteristics of Internal and External Pressure Variation for KTX (KTX차량 내외부의 압력변동 특성에 관한 연구)

  • 남성원
    • Journal of the Korean Society for Railway
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    • v.7 no.1
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    • pp.26-31
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    • 2004
  • A study is conducted to clarify internal and external pressure variation of passenger cabin for KTX. These pressure variation may give rise to the ear-discomfort for passenger and fatigue for carbody. In this study, the pressure variation of interior, gangway and exterior of KTX passenger car is measured by using the atmospheric pressure sensors and portable data acquisition system. The tunnel from 4000m to 200m in length are chosen far the investigation of tunnel length effects. From the results of experiment, the pressure variation of interior per second is under the ear-discomfort limitation in all of tunnel. And, We found that there are similar patterns of exterior pressure variation for each critical tunnel length. These results generally agree to RTRI's experimental result fur Shinkansen.

미국 Surry 원전사고 분석

  • 한국원자력산업회의
    • Nuclear industry
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    • v.7 no.4 s.50
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    • pp.86-87
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    • 1987
  • 미국원자력규제위원회(NRC)의 조사에 의하면 배관파단의 원인은 파단부 부근의 배관내면이 심하게 감육하고 있으며 원자로 트?후의 2차계의 압력변동에 견디지 못했기 때문이라고 보여지고 있다.

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Prediction of Broadband Noise for Non-cavitation Hydrofoils using Wall-Pressure Spectrum Models (벽면변동압력을 이용한 비공동 수중익의 광대역소음 예측 연구)

  • Choi, Woen-Sug;Jeong, Seung-Jin;Hong, Suk-Yoon;Song, Jee-Hun;Kwon, Hyun-Wung;Kim, Min-Jae
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.765-771
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    • 2019
  • With the increase in the speed of ships and the size of ocean structures, the importance of flow noise has become increasingly critical in meeting regulatory standards. However, unlike active investigations in aeroacoustics fields for airplanes and trains, which are based on acoustic analogy methods for tonal and broadband frequency noise, only the discrete blade passing frequency noise from propellers is considered in marine fields. In this study, prediction methods for broadband noise in marine propellers and underwater appendages are investigated using FW-H Formulation1B, which can consider the mechanism of primary noise generation of trailing edge noise. The original FW-H Formulation 1B is based on the pressure correlation function tolackitsgeneralityandaccuracy. To overcome these limitations, wall-pressure spectrum models are adopted to improve the generality in fluid mediums. The comparison of the experimental results obtained in air reveals that the proposed model exhibits a higher accuracy within 5 dB. Furthermore, the prediction procedures for broadband noise for hydrofoils are established, and the estimation of broadband noise is conducted based on the results of the computational fluid dynamics.

A Study on Estimation of Air Tightness for Train (철도차량의 공기압 기밀도 평가에 관한 연구)

  • Nam, Seong-won
    • Journal of the Korean Society for Railway
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    • v.19 no.5
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    • pp.576-584
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    • 2016
  • In this study, we measured the air tightness of a train using pressure variation in tunnels. To estimate the air tightness of a train is essential to comprehend the pressure variation of the cabin because air tightness is strongly related with ear discomfort. If we can determine the air tightness, we can predict the pressure variation of the cabin. Also, ear discomfort is a problem that can be caused in a high speed train, as well as in Korea's Great Train Express. In this study, we compared the various international standards for ear discomfort and estimated the air tightness of each vehicle based on experimental data obtained using the ITX, KTX and KTX-sancheon(honam) vehicles. The internal pressure variation of the trains is numerically calculated using the air tightness value. The results are good compared to the experimental results. Instead of flap type ventilation, in the future, continuous ventilation equipment will be needed for speed-up.