• Title/Summary/Keyword: Low Vibration

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Study on Low Frequency Characteristics of Rotary Compressor (로타리 압축기 저주파 특성에 관한 연구)

  • Byoungha Kwon;Park, Sinkyu;Insu Hwang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.384.2-384
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    • 2002
  • Compressor is a major noise source of air-conditioner. Especially, its low frequency band noise below 1000㎐ is very important because it will not be attenuated by passing through the cover panel and heat exchanger in air-conditioner. The factors affecting the low frequency band noise are studied by geometric similarity along with several experiments, and the low frequency noise is closely related with the discharge holes of muffler as well as the cavity of lower shell. (omitted)

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A Study on the Characteristics of the Suspension Components of Rolling Stocks in the Very low Temperature (극한 온도에서의 철도차량용 현가부품의 특성연구)

  • Choi, Byoung-Il;Na, Hee-Seung;Jang, Seung-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.45-48
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    • 2004
  • This study is a preview of characteristics of (1st/2nd) rubber suspension parts in low temperature, it will be researched before Trans Korean Railway and continental railway network connection. Rubber material characteristics are different to steel materials. Behavior of rubber material shows large deformation in hyper-elastic region. Moreover, added dashpot and low temperature condition shows various non-linear characteristics.

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Application of Acoustic Holography to Automobile Aeroacoustic Noise of Low Coherence (낮은 상관 관계를 갖는 자동차 공력 소음에 대한 음향 홀로그래피)

  • Nam, Kyoung-Uk;Kim, Yang-Hann
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.561-564
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    • 2004
  • Acoustic holography is applied to automobile aeroacoustic noise. Automobile aeroacoustic noise has low coherence due to multiple independent sources and measurement noise. This paper discusses the reliability of acoustic holography on this low coherence condition. Main subjects are the number and position of reference microphones, which is used for a step-by-step scanning method, and measurement noise. A real automobile experiment verifies the results.

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Studies on the Nutrition under Abnormal Environment(I) -Nutrition under Vibration- (이상환경하(異常環境下)의 영양문제(營養問題) 연구(硏究)(제1보) -진동하(振動下)의 영양문제(營養問題)-)

  • Yu, Jong-Yull
    • Journal of Nutrition and Health
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    • v.4 no.4
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    • pp.15-23
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    • 1971
  • On the assumption that the supplementation of certain nutrients or foods to the rice diet (low protein, low fat, and low vitamins) may decrease, to some extent, the degree of suffering from abnormal environments, such as vibration, noises, gases, dusts, smog etc. a series of experiments were started. As the first report the nutrition under vibration was studied in this experiment. Sixty (60) young growing male rats weighing about 65 grams were used, grouping to five (5) groups, twelve (12) rats each group. They were fed on the following five (5) experimental diets: rice diet (basal diet), rice diet+casein, rice diet+vitamins, rice $diet+{\alpha}-tocopherol$, and rice diet+ginseng powder (see the tables 1 and 2) for the period of 14 weeks experiment. During the experiment period the half number of the rats of each group were exposed to the three (3) hours vibration every day. The protective effect of each diet against the vibration may be summarized as follows. 1. The growth of rice diet group was impaired significantly under vibration, However, those of other groups (protein-supplemented, vitamin-supplemented, ${\alpha}-tocopherol-supplemented$ and ginseng-supplemented groups) were impaired much less compared with rice diet group. 2. The feed efficiency of the rice diet group was decreased significantly under vibration. It is estimated that the biological availability of nutrients was impaired under this environment. On the other hand, the feed efficiencies of protein supplemented, of vitamin supplemented, and of ginseng supplemented groups were not decreased under vibration, statistically. 3. There is tendency that the food spillages of vibration groups are higher than those of non-vibration groups. Especially it seems true in the case of rice diet group. The food spillage may be, to some extent, related with mental nervousness of animals. From the point that the food spillage of ginseng supplemented group is significantly lower than those of other groups it is thought ginseng acts some good role in protecting nervous system from suffering from vibration. 4. In all groups except protein supplemented group, liver fat of vibration group tends to be higher than that of non-vibration group. 5. It shows that, in general, the serum alkaline phosphatase activity of the vibration group is significantly higher than that of the non-vibration group. It seems that there may be, to some extent, corelation between the amount of liver fat and serum alkaline phosphatase activity. 6. There is tendency that, in rice diet group, the organs of vibration group are smaller than those of non-vibration group, especially lung is so. It is thought that this may be due to the poor growth of whole body size in vibration group.

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Cautious Blasting Works on the Po-Ryong Power Plant #3 #4 Foundation (#3 #4호기 보령화력발전소 기초공사 정밀발파공법)

  • Huh, Ginn
    • Journal of the Korean Professional Engineers Association
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    • v.21 no.4
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    • pp.12-18
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    • 1988
  • On the foundation work of Po-Ryong power plant #3 & #4. It was 30meters away from the running states of #1 & #2 plant site. In order to protect the #1 & #2 power plant facilities & factory structure. Allowable vibration was required below 0.07 gal. Therefore, it had to set up the anti-vibration trench to reduce the vibration reference and secondary. I applied the low gravity and low velocity explosives with M/S delay caps by cautious blasting pattern.

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Design and analyses of vibration driven energy harvester for low frequency (저주파수용 진동형 에너지 하베스터의 최적 설계 및 해석)

  • Ryu, Kyeong-Il;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.238-238
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    • 2010
  • This paper describes the design and analysis of vibration driven energy harvester for low frequency. The maximum output powers at load were $124.2{\sim}132.2\;{\mu}W$ with magnets during 3 mm input displacement at 6 Hz resonant frequency of system.

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An Experimental Study on the Pump Operating Characteristics with Low Flow Operation (펌프의 저 유량 운전특성에 관한 실험적 연구)

  • 오광석;신필권;박종호;심우건;조두연
    • Journal of KSNVE
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    • v.9 no.1
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    • pp.85-96
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    • 1999
  • For ASME Code pumps in nuclear power plants, inservice test is required to assess the operational readiness in accordance with ASME code and related regulations. The objective of this study therefore, is to develop the technical background of the degradation of pump performances and conditions due to low flow rate operation. In addition. the detection techniques of pump operating conditions are to be developed to enhance the safety and economy of nuclear power plants. A test loop consisted of pump, motor. water tank, flow rate measurements and piping system with flow control devices was established for this study. Two typical pumps, 1-stage volute pump and 3-stage turbine pump, were selected and the test was performed upon two major point of views ; i.e., pump discharge pressure pulsations analysis and pump vibration spectrum analysis. From the test results, it is concluded that (1) the pump vibration affected by the natural frequency of operating pump is significant in the low frequency zone (around 1 Hz) : the vibration amplitude. especially. is an important factor during low flow rate operation. and shall be monitored to ensure that it is within the limit of ASME OM code Part 6, (2) the vibration frequency and pump discharge pressure are affected by vane pass frequency and running speed, (3) the wave phenomena due to the compressiblity of water is anticipated during low flow rate operation. and the pump system shall be designed to prevent it and. finally, (4) the technical background of the degradation of pump performances and conditions due to low flow rate operation is provided.

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A Study on Field Vibration for Fault Cause Analysis of Glass Insulator on High-speed Railway (고속철도 유리애자 파손원인을 위한 현장 진동 연구)

  • Kim, Young-Seok;Shong, Kil-Mok;Bang, Sun-Bae;Kim, Sun-Gu;Ryu, Young-Tae
    • Proceedings of the KIEE Conference
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    • 2008.05a
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    • pp.189-190
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    • 2008
  • This study was investigated a possibility of fault of glass insulator due to vibration on high-speed railway. The proper vibration of 1-glass insulator have many frequency band and high amplitude showed in high frequency than low frequency. The proper vibration of strut tube insulator was lowest 170Hz, highest 1.5kHz. The field signal amplitude of viaduct and open route were biggest moment pantograph of high-speed rail. The surface vibration(V3) amplitude of strut tube insulator was biggest. From the FFT analysis of viaduct and open route, the strut tube insulator effect by vertical vibration was big, the frequency was 82.5Hz and 105Hz, respectively. However, in comparison with the proper vibration of strut tube insulator, the resonance was not observed. Although the amplitude of insulator is high, the possibility of fault is low because the glass insulator deterioration by the accumulation of vibration do not happen.

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Effect of Vibration on Dispersal of Cladosporium cladosporioides Bioaerosols

  • Lee, Byung-Uk
    • Journal of Microbiology and Biotechnology
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    • v.20 no.5
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    • pp.904-907
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    • 2010
  • The vibration of fungal cultures was evaluated to determine its potential effect on the dispersal of airborne fungal microorganisms suspected of being pathogens. An artificial vibration system, which simulates the actual environmental vibration of fungal structures, was designed and constructed for this purpose. Experiments featured the use of low-frequency vibrations similar to those induced by earthquakes. Within the range of conditions tested, the vibration of fungal cultures was found to affect the airflow-driven generation of bioaerosols.

Equivalent Beam Joint Modeling and Vibration Analysis Using Vehicle Side Key Sections (차체 Side Key Section 을 이용한 등가빔 결합부 모델링 및 강성해석)

  • Sung, Young-Suk;Yim, Hong-Jae;Kim, Ki-Chang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.252-257
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    • 2006
  • Low vibration characteristics of a vehicle are mainly influenced by the local stiffness of the joint structure beam section. The method of substituting equivalent beam element to spring element for the joint is presented. Formation process of the equivalent beam joint modeling is described in terms of key section properties. To get required dynamic characteristics section properties of the equivalent beam element are set to design variables. The study shows that the equivalent beam joint model can be effectively used for low frequency vibration analysis of a vehicle.

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