• Title/Summary/Keyword: Operating Sound

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Acoustic resonance by length of acoustic baffle at Finned Tube bank (핀-튜브군에서 배플 길이에 따른 음향공진)

  • 방경보;류제욱
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.98-103
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    • 2003
  • This paper presents phenomena of vibration and noise due to acoustic resonance in tube bank of a HRSG. Acoustic resonance is may arise when the vortex shedding frequency coincides with the acoustic natural frequency. At this tube bank, dominant frequencies of vibration in this system were 43.5, 67.5㎐. The 3$\^$rd/ acoustic natural frequency calculated was 68.5㎐. When the difference of vortex shedding frequency and acoustic natural frequency is within ${\pm}$20%, acoustic resonance could occur. In this system, in order to prevent acoustic resonance, acoustic baffle was installed in the tube bank before operating. But acoustic resonance occurred. So, we evaluate the effect of acoustic mode due to baffle extension length. After investigating, we did revise acoustic baffle to eliminate acoustic resonance effectively.

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Estimation of the Underwater Radiated Noise of a Naval Vessel Using Hull Vibration (선체진동을 이용한 함정의 수중방사소음 예측)

  • Han, Hyung-Suk;Lee, Kyung-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.5
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    • pp.394-400
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    • 2013
  • Underwater radiated noise is one of the important performances related to stealth of the naval vessel. However, the evaluation can't be performed frequently due to the cost. Therefore, the estimation method of the underwater radiated noise with average hull vibration is suggested in this paper assuming that the hull of the ship is infinite plate which consists of various unit plates. Through the experiment, the estimated noise is verified from the comparison to the measured data. In addition the difference of underwater radiated noise according to the operating equipments is estimated with measured vibration velocity.

Automatic Measurement of Noise and Vibration for Power seat DC motor in the vehicle (자동차 Power Seat 용 DC Motor의 소음 진동 자동 평가에 대한 연구)

  • 한형석;정의봉;김건혁;송도훈
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.1142-1147
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    • 2002
  • For the evaluation of the DC motor noise and vibration, usually it is rely on human feeling because some kinds of noise are not definitely represented by measurement Instrument such as sound meter. But when we consider time signal of the noise and vibration. It is possible to represent them. And in this paper. it is suggested to study output current shape of the motor because it Is the source to make speed and torque variation of the motor. If the current shape is not stable. it makes operating state of the motor unstable and produces noise and vibration. By analyzing signal at time and frequency of noise and vibration and current shape. it is possible to automation of the noise and vibration measurement in the Production line.

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Study on the Noise Characteristic of Centrifugal Fan operating at High Pressure Region (흡입저항이 높은 원심홴 소음특성에 관한 연구)

  • Jung, Yeun-Young;Park, Jin-Won;Jeon, Wan-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1011-1014
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    • 2006
  • Turbo blower generates high peaks when it operates at high pressure region. The fan of the air-cleaner system, operates especially high pressure region due to several filters, generates high noise level. In this case, the tonal sound of BPF makes people annoyance. The blower of air-cleaner has several high resistance filters in its inlet area and rotates above 900rpm Moreover, for the compact design, the size of the blower should be reduced 10%. The reduced diameter of blower makes low flow rate and high noise level. In order to reduce the noise, new blade shape was suggested and optimized

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Measurement and Analysis of Knock Using a Microphone Sensor in a S.I. Engine (전기점화기관에서 마이크로폰 센서를 이용한 노킹 측정 및 분석)

  • 황승환;이종화;임진수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.3
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    • pp.202-208
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    • 1997
  • The knocking is one of major parameters to improve engine performance in a spark ignition engine. Many researches have been carried out to identify them using cylinder pressure, vibration signal and so on. In the present study, measurement and analysis was conducted to set up the criteria of knock occurrence by using microphone signal. Cylinder pressure was measured for the reference signal of knocking. It has been observed that resonance frequencies of pressure wave are nearly independent of engine operating conditions such as engine speed, air fuel ratio, load and octane number of fuel within to limited experimental conditions. SDBP(sum of different band-pass data) method using resonance frequency of knock was proposed for estimating knock intensity. SDBP method is superior to identify knock occurrence and its intensity in case of sound pressure measurement.

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Noise Reduction of a Reciprocating Compressor in a High Frequency Range (왕복동 압축기의 고주파수 대역 소음 저감)

  • Lee, Jin Woo;Lee, Jeawon;Joo, Jae Man
    • 유체기계공업학회:학술대회논문집
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    • 2004.12a
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    • pp.521-526
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    • 2004
  • This paper introduces works performed for reducing high frequency noise of a reciprocating compressor. Noise in a high frequency range strongly affects sound quality as well as increases total noise level of the compressor. In order to reduce the noise, two different works were carried out. the first work was to measure the vibration Power transferred through suspension spring and discharge pipe; and the second one was to obtain operational deflection shape from cross-power spectrum measured on shell. Based on the information, Adequate structural modification of the transfer path and shell resulted in noise reduction in a high frequency range.

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Development of Digital Endoscopic Image Processing System (디지탈 내시경 영상처리 시스템의 개발)

  • 송철규;이영묵
    • Journal of Biomedical Engineering Research
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    • v.18 no.2
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    • pp.121-126
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    • 1997
  • Endoscopy has become a crucial diagnostic and therapeutic procedure in clinical areas. Over the past three years, we have developed a computerized system to record and store clinical data pertaining to endoscopic surgery of laparascopic cholecystectomy, pelviscopic endometriosis, and surgical arthroscopy. In this study, we developed a computer system, which is composed of a frame yabber, a sound board, a VCR control board, a LAN card and EDMS(endoscopic data management software. Also, computer system has controled peripheral instruments such as a color video printer, a video cassette recorder, and endoscopic input/output signals(image and doctor's comment). Digital endoscopic data management system is based on open architecture and a set of widely available industry standards, namely: windows 3.1 as a operating system, TCP/IP as a network protocol and a time sequence based database that handles both images and doctor's cotnments. For the purpose of data storage, we used MOD and CD-R. Digital endoscopic system was designed to be able to store, recreate, change, and compress signals and medical images.

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Numerical Analysis of Underwater Propeller Noise(Part 1. Non-Cavitating Noise) (수중 프로펠러의 소음 예측에 관한 연구(Part 1. 비공동 소음))

  • 설한신;이수갑;표상우;서정천
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.2
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    • pp.21-32
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    • 2004
  • The non-cavitating noise of underwater propeller is considered numerically in this study. The main purpose is to analyze non-cavitating noise from underwater propellers in various operating conditions with different configurations. Noise is predicted by using time-domain acoustic analogy, boundary element method, and computational hydro-acoustics. The flow field is analyzed with potential-based panel method, and then time-dependant pressure data are used as the input for Focus Williams-Hawkings formulation to predict far field acoustics. Furthermore, boundary element method and computational hydro-acoustics are also considered to investigate duct propeller and ducted multi-stage propeller to consider the reflection and diffraction of sound waves. With this methodology, noise intensity and directivity of each noise sources could be well analyzed.

A Study of Loss Prevention for Methanol Synthesis Process Based on Exergy Analysis (엑서지 해석에 기초한 메탄올합성공정의 손실예방책 연구)

  • Cho, Hyo-Eun;Chung, Yonsoo
    • Clean Technology
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    • v.6 no.2
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    • pp.129-137
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    • 2000
  • A methanol synthesis process via reverse-water-gas-shift and methanol formation reactions has been analyzed using the notion of exergy. The analysis has been based on the simulation results with the aid of real operating data. Driving and material exergy losses have been defined and quantified, respectively. Locations and the reason of major exergy losses have been pinpointed and improvement strategies have been suggested. It had been noted that the exergy analysis can provide a sound scientific base for adopting the concept of industrial ecology and developing loss prevention schemes.

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A Study on Monitoring Technique for Home Server based on Web Camera (웹 카메라 기반 홈 서버용 모니터링 기술에 관한 연구)

  • Jeong Jong-Geun;Cheon Sung-Hwan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.8
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    • pp.1754-1761
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    • 2005
  • A monitoring system for the security is increasingly demanded in line with the issue of the infringement of privacy. This paper has conducted the study on the monitoring technique via the Internet using PC or PDA. This is a monitoring system for web-camera based home server, which transmits the images and sound data captured by mike-embedded USB camera, though multiplexer of H.263 and internet. It integrates the operating processors of each device into a unified drive module and provides it the operator to facilitate the system operation and maintenance.