• Title/Summary/Keyword: The period of Vibration

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Vibration Characteristics of the Axially Moving Continuum with Time-Varying Length: Spagetti Problem (축방향으로 이동하며 길이가 변하는 연속체의 진동특성: 스파게티 문제에 응용)

  • 사재천;이승엽;이민형
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.385-392
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    • 2001
  • Time-dependent frequency and energy of free vibration of the Spagetti problem, that is the axially moving continuum with time-varying length, are investigated. Exact expressions for the natural frequency and time-varying vibration energy are derived by dealing with traveling waves. When the string length is increased, the vibration period increases, but the free vibration energy varies as a function of both translating velocity and boundary velocity of the continuum. However, when the string undergoes retraction, the vibration energy increases with time, String tension together with non-zero instantaneous velocity at the moving boundary results in energy variation.

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Study on the Precision Method of Measuring angular displacement for the Angular Vibration Calibration System (회전 진동 교정 장치 구현을 위한 고정밀 측정기법에 대한 연구)

  • Cheung, Wan-Sup;Lee, Yong-Bong;Lee, Doo-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.685-688
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    • 2004
  • This paper addresses the study on developing the angular vibration calibration system which requires the highly accurate measurement technique of the amplitude and period of an oscillating angular motion. Two developed models for the low and high frequency ranges are introduced and their main features are also compared. In addition to the angular vibration exciters, a new measurement method, referred to the 'equi-angle sampling method', is proposed and its theoretical backgrounds are introduced. The proposed method is shown to provide much less measurement uncertainty, compared the fringe counting method. Experimental results demonstrate what amount of angular vibration amplitude measurement uncertainty is improved by suing the proposed equi-angle sampling method.

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Free Vibration and Dynamic Stability of the Axially Moving Continuum with Time-varying Length (축방향으로 이동하며 길이가 변하는 연속체의 자유 진동 및 동적 안정성)

  • 사재천;이민형;이승엽
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.4
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    • pp.272-279
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    • 2002
  • The time-dependent frequency and energy of free vibration of the spagetti problem, that is the axially moving continuum with time-varying length, are investigated. Exact expressions for the natural frequency and time-varying vibration energy are derived by dealing with traveling waves. The vibration period increases with increasing length, but the free vibration energy decreases. When the string undergoes retraction, the vibration energy increases with time. The free response of the time-varying string is represented by superposing two traveling waves.

A Fundamental Study about Vibration Analysis of Plasma Rock Fragmentation Method (플라즈마 파암공법의 진동분석에 관한 기초적인 연구)

  • 윤지선;김상훈
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.129-136
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    • 2001
  • Blasting method is used most engineering works for rock excavation. Blasting method is done much to upgrade of operation efficiency, contraction of construction period than other method. But blasting method happens damage by blasting vibration, nose and scattering. Therefore this study examined about effect, characteristic and application of Plasma method. To confirm effect measured vibration, noise and frequency, and analyzed data compare with general blasting.

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A Case Study to Minimize Effect of Blasting Vibration and Noise on Animal Casualties (발파진동과 소음이 가축에 미치는 영향에 관한 사례연구)

  • 안명석;김종대;황소중
    • Journal of KSNVE
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    • v.11 no.1
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    • pp.104-110
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    • 2001
  • The demand of blasting work in civil engineering work is increasing because of the increasing social infra-structural construction work. The blasting method creates large benefit in regard to the economic aspect and shortening construction period. This method, however, has problems to be solved in respect to the blasting vibration and noise. Blasting vibration and noise have been studied by many workers, regarding to the impact on the structure and human body. This investigation is concerned on the affect of blasting vibration and noise on the animals which is relatively new. In general, animals have inferior mental capacity than human in hearing but have higher sensitivity on the vibration and noise due to blasting. The object of this study is to investigate an appropriate measurement of lessening damage on the animals by vibration and noise due to blasting.

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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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Effects of Isolation Period Difference and Beam-Column Stiffness Ratio on the Dynamic Response of Reinforced Concrete Buildings

  • Chun, Young-Soo;Hur, Moo-Won
    • International Journal of Concrete Structures and Materials
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    • v.9 no.4
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    • pp.439-451
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    • 2015
  • This study analyzed the isolation effect for a 15-story reinforced concrete (RC) building with regard to changes in the beam-column stiffness ratio and the difference in the vibration period between the superstructure and an isolation layer in order to provide basic data that are needed to devise a framework for the design of isolated RC buildings. First, this analytical study proposes to design RC building frames by securing an isolation period that is at least 2.5 times longer than the natural vibration period of a superstructure and configuring a target isolation period that is 3.0 s or longer. To verify the proposed plan, shaking table tests were conducted on a scaled-down model of 15-story RC building installed with laminated rubber bearings. The experimental results indicate that the tested isolated structure, which complied with the proposed conditions, exhibited an almost constant response distribution, verifying that the behavior of the structure improved in terms of usability. The RC building's response to inter-story drift (which causes structural damage) was reduced by about one-third that of a non-isolated structure, thereby confirming that the safety of such a superstructure can be achieved through the building's improved seismic performance.

A Study on the Tunnel Blasting Technique with a Combined Application of Electronic Detonators and Low Vibration Explosives in a Close Proximity to a Safety things (전자뇌관과 미진동폭약을 활용한 보안물건 초근접 구간에서의 터널발파공법 적용에 관한 연구)

  • Oh, Sei young;Lee, Chun sik;Lee, Ki keun;Lee, Dong hee;Lee, Seung jae;Park, Jong ho
    • Explosives and Blasting
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    • v.35 no.4
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    • pp.36-47
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    • 2017
  • Due to civil complaints on vibrations and noises arising from blasting, mechanical excavation has been widely used for tunneling rather than the method of blasting, especially in the case of being in a close-proximity of 10M-20M range to a safety-thing. However, mechanical excavation, though less, it does increase the cost of whole construction project as the period of excavation is much prolonged from lack of constructability. This study aims to research and develop an effective blasting method that can ensure the constructability of shortened excavation period whilst not compromising the safety of the safety-things in a proximity to the blasting site by using a combination of an electronic detonator that can accurately control its delay period and a Low Vibration Explosives(LoVEX) that is effective on vibration control.

Nonlinear Dynamic Analysis of a Cantilever Tube Conveying Fluid with System Identification (시스템 규명을 통한 외팔 송수관의 비선형 동적 거동 해석)

  • 임재훈;정구충;최연선
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.495-500
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    • 2003
  • The vibration of a flexible cantilever tube with nonlinear constraints when it is subjected to flow internally with fluids is examined by experiment and theoretical analysis. These kind of studies have often been performed that finds the existence of chaotic motion. In this paper, the important parameters of the system leading to such a chaotic motion such as Young's modulus and coefficient of viscoelasticity in tube material are discussed. The parameters are investigated by means of a system identification so that comparisons are made between numerical analysis using the parameters of a handbook and the experimental results. The chaotic region led by several period-doubling bifurcations beyond the Hopf bifurcation is also re-established with phase portraits and bifurcation diagram so that one can define optimal parameters for system design.

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Significance of Acoustic Parameter - RAP, PPQ, APQ- in Hoarseness (애성환자에서 음향지표인 RAP, PPQ 및 APQ의 유용성)

  • 안철민;이종혁;강현국;이용배
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.6 no.1
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    • pp.22-26
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    • 1995
  • Change of voice, espicially hoarseness show irregular vibration of vocal cord. So, computerized acoustic analysis has presented many acoustic parameters for objective evaluation of voice. We objectively investigated the vocal vibration of normal persons and hoarseness patients in Korea. The RAP(relative average perturbation), PPQ(pitch period perturbation quotient) and APQ(amplitude perturbation quotient) of normal persons were compared with that of hoarseness patients with multidimensional voice program for the possibility of distinguishing the pathologic vocal vibration from normal. Authors agree that RAP, PPQ and APQ showed interesting differences between the normal and the hoarseness patients by the multivariate statistical analysis. In conculusion, relative average perturbation, pitch period perturbation and amplitude perturbation quotient might be meangingful screening parameters distinguishing hoarseness patients from normal.

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