• 제목/요약/키워드: vibration and sound

검색결과 2,243건 처리시간 0.027초

Liquidity Evaluation on the Horizontal Branch Pipe Connected to a Food Waste Disposer (디스포저에 의한 음식물류폐기물 횡지관 유동성 평가)

  • Jang, Choon-Man;Lee, Sang-Moon;Kim, Chul-Kyu;Park, Se-Joon;Yu, Jong-Chan
    • The KSFM Journal of Fluid Machinery
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    • 제20권1호
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    • pp.53-58
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    • 2017
  • This paper describes liquidity evaluation on the horizontal branch pipe connected to a food waste disposer and performance of five disposers marketed. Experimental apparatus for analyzing the five disposers has been introduced to measure vibration, sound level and power consumption of the disposers. Simulator for analyzing the required water velocity to avoid waste jam inside the pipe connected to a food waste disposer has been designed and constructed. The simulator can control some experimental parameters: pipe slope, disposer supply water quantity, food waste materials and operation time of a disposer. Throughout the experimental measurements of the disposers marketed, it is found that the time need to crash food waste is about 20 seconds on the average. At the same flow condition, increase rate of internal water velocity is accelerated as the pipe slope increases. The water velocity inside the pipe having 50 A and slope of 1/50 is 0.26 m/s when the water flowrate to supply the disposer is 16 l pm. Considering the specific gravity and adhesion property of food waste, water velocity of the horizontal branch pipe connected to a food waste disposer need to excess 0.26 m/s at least to avoid the waste blockage inside the pipe.

A Study on Interior Noise Characteristics of High-speed Trains (고속철도 차량의 실내소음 특성 연구)

  • Noh, Hee-Min;Choi, Sunghoon;Kim, Seog-Won;Hong, Suk-Yoon
    • Journal of the Korean Society for Railway
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    • 제16권1호
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    • pp.14-19
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    • 2013
  • Because excessive interior noise when riding a high-speed train leads to annoyances, fatigue and stress for passengers, interior noise reduction methods should be considered. In particular, a high-speed train operated in various operation environments, and in South Korea, these include open fields and tunnels. Therefore, a specific study about changes in interior noise characteristics according to different environments is necessary. For this reason, the interior noise characteristics on a KTX train and on the KTX-Sancheon train were analyzed from noise measurements using microphones in this paper. Vibrations on the axles, bogies and floor were also measured, are these area are structural paths for interior noise. From this research, the interior noise characteristics according to the driving speed were deduced and the effects on interior noise by driving environments such as open fields and tunnels were investigated. Furthermore, the effect on interior noise by axles, bogies and floor vibrations were analyzed from a transfer function analysis.

On mixing the Rayleigh-Ritz formulation with Hankel's function for vibration of fluid-filled functionally graded cylindrical shell

  • Hussain, Muzamal;Naeem, Muhammad Nawaz;Shahzad, Aamir;Taj, Muhammad;Asghar, Sehar;Fatahi-Vajari, Alireza;Singh, Rahul;Tounsi, Abdelouahed
    • Advances in Computational Design
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    • 제5권4호
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    • pp.363-380
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    • 2020
  • In this paper, a cylindrical shell is immersed in a non-viscous fluid using first order shell theory of Sander. These equations are partial differential equations which are solved by approximate technique. Robust and efficient techniques are favored to get precise results. Employment of the Rayleigh-Ritz procedure gives birth to the shell frequency equation. Use of acoustic wave equation is done to incorporate the sound pressure produced in a fluid. Hankel's functions of second kind designate the fluid influence. Mathematically the integral form of the Lagrange energy functional is converted into a set of three partial differential equations. Throughout the computation, simply supported edge condition is used. Expressions for modal displacement functions, the three unknown functions are supposed in such way that the axial, circumferential and time variables are separated by the product method. Comparison is made for empty and fluid-filled cylindrical shell with circumferential wave number, length- and height-radius ratios, it is found that the fluid-filled frequencies are lower than that of without fluid. To generate the fundamental natural frequencies and for better accuracy and effectiveness, the computer software MATLAB is used.

Development of Portable Memory Type Radiation Alarm Monitor (휴대용 메모리형 방사선 경보장치 개발)

  • Son, Jung-Kwon;Lee, Myung-Chan;Song, Myung-Jae
    • Journal of Radiation Protection and Research
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    • 제22권4호
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    • pp.263-272
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    • 1997
  • A Radiation Alarm Monitor has been developed and manufactured in order to protect radiation workers from over-exposure. A visual and audible alarm system has been attached to initiate evacuation when accident occurs such as an unexpected change of radiation level or an over-exposure. The Radiation Alarm Monitor installed with microprocessor can record the information of radiation field change between 90 min. before the alarm and 30 min. after the alarm and also provide the data to an IBM compatible computer to analyze the accidents and to set a counterplan. It features a wide detection range of radiation field(10 mR/h-100 R/h), radiation field data storage, portability, high precision (${\pm}5%$) due to self-calibration function, and adaption of a powerful alarm system. According to ANSI N42.17A, the most stringent test standards, performance tests were carried out under various conditions of temperature, humidity, vibration, and electromagnetic wave hindrance at Korea Research Institute of Standards & Science (KRISS). As a result, the Radiation Alarm Monitor passed all tests.

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Free Vibrations and Buckling Loads of Axially Loaded Cross-Ply Laminated Composite Beam-Columns with Multiple Delaminations (다층간분리된 직교 적층 보-기둥의 자유진동과 좌굴하중)

  • 이성희;김형열;박기태;박대효
    • Journal of the Computational Structural Engineering Institute of Korea
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    • 제15권3호
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    • pp.523-534
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    • 2002
  • Free vibration and buckling analysis of multi-delaminated composite beam-columns subjected to axial compressive load is performed in the present study In order to investigate the effects of multi-delaminations on the natural frequency and the elastic buckling load of multi-delaminated beam-columns, the general kinematic continuity conditions are derived from the assumption of constant slope and curvature at the multi-dclamination tip. The characteristic equation of multi-delaminated beam-column is obtained by dividing the global multi-delauunated beam-columns into segments and by imposing recurrence relation from the continuity conditions on each sub-beam-column. The natural frequency and the elastic buck)ing load of multi-delaminated beam-columns according to the incremental load of axial compression, which is limited to the maximum elastic buckling load of sound laminated beam-column, are obtained. It is found that the sizes, locations and numbers of multi-delaminations have significant effect on natural frequency and elastic buckling load, especially the latter ones.

Importance-Performance Analysis about Early Mobilization after Abdominal Surgery Patients in Surgical Ward Nurses (복부수술 환자의 조기운동에 대한 외과병동 간호사의 중요도-수행도 분석)

  • Kim, Bo Eun;Choi, Hye-Ran
    • Journal of Digital Convergence
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    • 제19권12호
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    • pp.567-575
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    • 2021
  • This study was aimed to identify surgical ward nurses' importance-performance awareness toward early mobilization after abdominal surgery patients. The date were collected from 162 nurses and the importance and performance of early mobilization were analyzed by the IPA method. The collected data were analyzed using the SPSS/WIN 25.0 by implementing descriptive statistics, independent t-test, paired t-test, and ANOVA. Early mobilization was divided into exercise of pulmonary complications and early ambulation. As a result of the study, the areas requiring concentration were 'check risk of aspiration', and areas requiring improvement were 'oral care', 'check lung sound', 'percussion/vibration', 'suction', and 'reinforcement exercise in bed'. Therefore, each item of early mobilization is recommended to reduce the gap between importance and performance in clinical care.

A Study of Explosive Jet-cutting Technology by Linear Shape Charges (성형폭약에 의한 폭발절단기술에 관한 연구)

  • 이병일;박근순;공창식;김광태
    • Tunnel and Underground Space
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    • 제10권4호
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    • pp.516-525
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    • 2000
  • Recently, the demand for pollution-free demolition work of old reinforced concrete and steel structure has rapidly increased as the redevelopment of urban area has been accelerated. This study deals with linear shape charges for explosive jet cutting on steel structure. We have tested material and shape of steel structure, characteristics of thickness and strength, shape of linear shape charges, type of shape charges, cumulative charges, type of liner, stand-off distance, detonation method. effect of sound and vibration by air blast in explosive jet cutting method. So, We developed linear shape charges in order to take advantage of optimum explosive jet cutting condition. Shape charges were made of PETN explosives. We obtained the experimental formula to decide the amount of explosive needed for thickness of steel structure plate. There are prospects for application of the explosion curving technology under the open space conditions for dismantling the steel structure and steel bridge, scrapped old boats, which are going out of service.

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An Experimental Study on Longitudinal Shear Capacity of Composite Slab Embedded with Silence Insulator (방음재를 삽입한 합성슬래브의 수평전단성능에 관한 실험적 연구)

  • Lee, Seon-Keun;Lee, Chy-Hyoung;Yoon, Sung-Kee
    • Journal of the Korea institute for structural maintenance and inspection
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    • 제22권5호
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    • pp.64-71
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    • 2018
  • This paper provides the results for experimental study on longitudinal shear performance for new-concept composite slabs embedded with silence insulator. Longitudinal shear capacity tests are used to predict characteristics of composite action between the concrete block, silence insulator and deckplate. A total set of 7 Push-Down specimens are tested to clarify the composite action between the concrete block, silence insulator and deckplate. Parameters in this study are the width of T-type bar, the depth of reinforced bar and the thickness of silence insulator. The results from experimental study on longitudinal shear capacity for new-concept composite slabs applied T-type bar, Reinforced bar and Silence insulator are summarized as follows. In test result, the Longitudinal Shear Capacity of the new concept specimen is 2 times excellent than basic specimen with safety. It is expected that applying the proposed composite slab detail at the actual site will provide a significant safety factor in structural aspect of the existing composite slab, and greatly contribute to the improvement capacities of resisting vibration and sound.

A Numerical Method for Analysis of the Sound and Vibration of Waveguides Coupled with External Fluid (외부 유체와 연성된 도파관의 진동 및 소음 해석 기법)

  • Ryue, Jung-Soo
    • The Journal of the Acoustical Society of Korea
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    • 제29권7호
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    • pp.448-457
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    • 2010
  • Vibrations and wave propagations in waveguide structures can be analysed efficiently by using waveguide finite element (WFE) method. The WFE method only models the 2-dimensional cross-section of the waveguide with finite elements so that the size of the model and computing time are much less than those of the 3-dimensional FE models. For cylindrical shells or pipes which have simple cross-sections, the external coupling with fluids can be treated theoretically. For waveguides of complex cross-sectional geometries, however, numerical methods are required to deal with external fluids. In this numerical approach, the external fluid is modelled by the boundary elements (BEs) and connected to WFEs. In order to validate this WFE/BE method, a pipe submerged in water is considered in this study. The dispersion diagrams and point mobilities of the pipe simulated are compared to those that theoretically obtained. Also the acoustic powers radiated from the pipe are predicted and compared in both cases of air and water as an external medium.

Noise Analysis and Reduction Methods of the All-in One Window Ventilation System (창호일체형 환기장치의 소음분석 및 저감방안)

  • Park, Chan-Jae;Haan, Chan-Hoon
    • The Journal of the Acoustical Society of Korea
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    • 제32권1호
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    • pp.43-55
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    • 2013
  • The window ventilation system based on the heat recovery device was developed which make air ventilation possible without opening the windows. However, mechanical and aerodynamic noises were come to pass which annoyed people in rooms. In the present study, noise of new window ventilation system was measured in both general room and anechoic chamber. Also, the noise path was detected to find cause of noise generation and vulnerable area of the device. Sound absorptive and insulation materials were applied to mitigate the noise. Finally, an alternative noise control method was suggested which can satisfy with the indoor noise standards. As a result, it was shown that the cause of noise was the low transmission loss in the ventilation system. As a result, it was shown that the main noise source of the ventilation system was the blower and the major cause of noise was the low transmission loss of the ventilation system. It is also concluded that the noise levels complies with the noise standards of 40 dBA when 2 mm rubber sheet is applied inside the ventilation system.