• Title/Summary/Keyword: Anti-vibration design

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Study on Noise Reduction of DLP Front Home Theater Projector (가정용 DLP 프로젝터의 소음 저감에 관한 연구)

  • Jang Dong Seob;Park Chul Min;Park Dae Kyong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.9 s.90
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    • pp.861-867
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    • 2004
  • For the evaluation of acoustic noise of a DLP projector, vibration and sound characteristics of a DLP projector were studied. The acoustic noise of DLP projector could be classified into three categories, that is, the direct noise from a body of rotation, the air-bone noise generated from turbulence or vortex occurred during cooling process and the structural born noise produced by vibrating elements. Cooling fans and color filter wheel which rotates at 9000 rpm are main causes of acoustic noise induced in DLP projector. Since the structure of an optical module in a DLP projector can be excited by the excessive vibration of a color filter wheel, the structural design for anti-vibration should be considered. To make a reduction of overall acoustic noise, the anti-vibration design and the enclosing structure have been studied and applied to a color filter wheel.

The System Position from High Firing Rate of Anti-Aircraft Gun system (고발사율 대공포 발사에 따른 체계자세 연구)

  • Hwang, Boo Il;Lee, Boo Hwan;Kim, Chi Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.6
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    • pp.611-615
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    • 2015
  • Anti-aircraft gun system is used for low-level air defense system and has more than twin guns with high firing rate in order to maximize the capability of defense. Gun's vibration and bullet's variance has a critical effect on accuracy and hit probability of weapon system such as anti-aircraft gun system with high firing rate. Typical mechanism to reduce the amount of vibration and shock during gun-fire process is very important design factor. In this paper, the suspension characteristics of the vehicle are studied for the improvement of isolating performance of gun firing system with high firing rate. Gun fire test for the vehicle is conducted and computational models using Recurdyn and Adams are created based on test results. Through this study, results of computational analysis are compared with the real test results, which includes type, location and quantity of suspension and gun mechanism are selected for anti-aircraft gun. From the result of this study, we could make basic design and consider the proper component of the system such as suspension and gun spring.

Analysis and Experiment of the Dynamic Characteristics of Rubber Materials for Anti-Vibration under Compression (압축하중을 받는 방진고무의 동특성 해석 및 실험)

  • 김국원;임종락;한용희;손희기;안태길
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.602-607
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    • 1998
  • Rubber materials are extensively used in various machine design application, mainly for vibration/shock/noise control devices. Over the years an enormous effort has been put into developing procedures to provide properties of rubber material for design function. However, there are still a lot of difficulties in the understanding of dynamic characteristics of the rubber components in compression. In this paper, the dynamic characteristics of rubber materials for anti-vibration under compression were investigated. Dynamic and static tests for rubber material with 3 different hardness were performed. In dynamic tests, non-resonance method, impedance method, was used to obtain the complex modulus (storage modulus and loss factor) and the effects of static pre-strain on the dynamic characteristics were investigated. Also, a relation equation between linear dynamic and nonlinear static behavior of rubber material was discussed and its usefulness to predict their combined effects was investigated.

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Shape Optimal Design of Anti-Vibration Rubber Assembly to Reduce the Vibration of a Tractor Cabin (트랙터 캐빈의 진동저감을 위한 방진고무의 형상최적설계)

  • Choi, Hyo-Joon;Lee, Sang-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.4
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    • pp.657-663
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    • 2018
  • In this study, shape optimization was performed to improve the vibration isolation capability of an anti-vibration rubber assembly, which is used in the field option cabin of agricultural tractors. A uniaxial tension test and biaxial tension test were performed to characterize the hyper-elastic material properties of rubber, and the data were used to calibrate the material model used in the finite element analyses. A field test was performed to quantify the input excitation from the tractor and the output response at the cabin frame. To account for the nonlinear behavior of rubber, static analyses were performed and the load-displacement curve of rubber was derived. The stiffness of the rubber was calculated from this curve and input to the harmonic analyses of the cabin. The results were verified using the test data. Taguchi's parameter design method was used to find the optimal shape of the anti-vibration rubber assembly, which indicated a shape with reduced stiffness. The vibration of the cabin frame was reduced by the optimization by as much as 35% compared to the initial design.

Experimental Analysis of Axial Vibration in Slim-type Optical Disc Drive (슬림형 광 디스크 드라이브의 축방향 진동에 대한 실험적 해석)

  • 박대경;전규찬;이성진;장동섭
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.694-699
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    • 2002
  • As the demand for slim laptops requires ion'-height optical disc drives, vibration problems of optical disc drives are of great concern. Additionally, with the decrease of a track width and a depth of focus in high density drives, studies on vibration resonance between mechanical parts become more important. From the vibration point of view, the performance of optical disc drives is closely related with the relative displacement between a disc and an objective lens which is controlled by servo mechanism. In other words, to read and write data properly, the relative displacement between an optical disc and an objective lens should be within a certain limit. The relative displacement is dependent on not only an anti-vibration mechanism design but also servo control capability. Good servo controls can make compensation for poor mechanisms, and vice versa. In a usual development process, robustness of the anti-vibration mechanism is always verified with the servo control of an objective lens. Engineers partially modify servo gain margin in case of a data reading error. This modification cannot correct the data reading error occasionally and the mechanism should be redesigned more robustly. Therefore it is necessary to verify a mechanism with respect to the possible servo gain plot. In this study we propose the experimental verification method far anti-vibration mechanism with respect to the existing servo gain plot. This method verifies axial vibration characteristics of optical disc drives on the basis of transmissibility. Using this method, we verified our mechanism and modified the mechanism for better anti-vibration characteristics.

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Experimental Analysis of Axial Vibration in Slim-type Optical Disc Drive (슬림형 광 디스크 드라이브의 축방향 진동에 대한 실험적 해석)

  • 박대경;전규찬;이성진;장동섭
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.11
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    • pp.833-839
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    • 2002
  • As the demand for slim laptops requires low-height optical disc drives, vibration problems of optical disc drives are of great concern. Additionally, with the decrease of a track width and a depth of focus in high density drives, studies on vibration resonance between mechanical parts become more important. From the vibration point of view, the performance of optical disc drives is closely related with the relative displacement between a disc and an objective lens which is controlled by servo mechanism. In other words, to read and write data properly, the relative displacement between an optical disc and an objective lens should be within a certain limit. The relative displacement is dependent on not only an anti-vibration mechanism design but also servo control capability. Good servo controls can make compensation for poor mechanisms, and vice versa. In a usual development process, robustness of the anti-vibration mechanism is always verified with the servo control of an objective lens. Engineers partially modify servo gain margin in case of a data reading error. This modification cannot correct the data reading error occasionally and the mechanism should be redesigned more robustly. Therefore it is necessary to verify a mechanism with respect to the possible servo gain plot. In this study we propose the experimental verification method for anti-vibration mechanism with respect to the existing servo gain plot. Thismethod verifies axial vibration characteristics of optical disc drives on the basis of transmissibility. Using this method, we verified our mechanism and modified the mechanism for better anti-vibration characteristics.

Numerical Analysis of the Mechanical Impedance and Transmitted Vibration of the Foundation for the Equipment in a Naval Vessel (수치해석을 이용한 함정용 장비 받침대의 기계적 임피던스 및 전달 진동 분석)

  • Han, Hyung-Suk;Son, Yoon-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.5
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    • pp.462-467
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    • 2009
  • Reduction of the structure-borne noise of the naval vessel is very important in order to reduce the underwater radiated noise of it. One of the important factors to reduce the structure-borne noise of the installed machine in a ship is the design of the foundation having sufficiently high mechanical impedance. In this paper, the mechanical impedance of the foundation for the fan-coil unit in a naval vessel is evaluated numerically according to variation of the thickness of the foundation. And also, the forced vibration analysis is conducted considering the dynamic property of the anti-vibration mount. Through the analysis results, it can be known that the dynamic property of the anti-vibration mount should be considered when the minimum level of the mechanical impedance of the foundation is set.

A Study on the Blanking Characteristic of Anti- Vibration Sheet Metal (제진 강판의 블랭킹 가공 특성에 관한 연구)

  • 이광복;이용길;김종호
    • Transactions of Materials Processing
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    • v.12 no.8
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    • pp.724-729
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    • 2003
  • In order to study the shearing characteristic of anti-vibration sheet metal which is used to reduce vibration noise, a blanking die was manufactured to blank a workpiece. The variables employed in this study were clearance, type of stripper plate, position of the rubber layer and type of the die design. These variables were used to study the effects on burr height, blank diameter and camber height. In the case of burr height from experimental investigation, the push-back die, combined with a movable stripper plate, showed greater burr height. The rubber-top position of a workpiece resulted in better qualities regardless of working variables. In the comparison of diameter measurement, the use of the push-back die with a fixed stripper plate, with a 4.5% clearance, showed better accuracy. For comparing camber height, the push-back die resulted in less cambering than the drop-through die. Also, the larger the clearance, the greater was the camber height. Considering experimental results, the shearing of anti-vibrational sheet metal is best achieved when the rubber layer is laying on the top, blanked with a fixed stripper plate in a push-back die, with a 4.5% clearance.

Consideration of Structural Damage of Fresh Water Tank for 2,600 TEU Container Vessel (2,600 TEU Container Vessel 의 Fresh Water Tank 구조손상 사례 고찰)

  • Shin Sung-Kwang;Ahn Hyung-Joon;Choi Eui-keol;Koh Myeong-Seob;Leem Hyo-Kwan
    • Special Issue of the Society of Naval Architects of Korea
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    • 2005.06a
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    • pp.216-221
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    • 2005
  • Many tanks such as a fresh water tank, an aft peak tank and oil tanks are arranged in the engine room and aft part areas of the ship. By added mass effect of the fluid inside the tanks, the natural frequency will be changed according to filling height of the tank. For this reason, there is possibility of occurrence of excessive vibration by resonance between natural frequencies of local structure and excitation frequencies of the propeller or main engine. Therefore, calculation of natural frequencies is required for structure for many types of tank which are contacting with water or oil to consider added mass effect for anti-resonance design at design stage. In this study, a case of structure damage on the fresh water tank for 2600 TEU container vessel is introduced. In addition, natural frequency analysis and vibration measurement have been performed to investigate vibration characteristics for excessive vibration control.

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