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  • Title/Summary/Keyword: 진동물체

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Parametric Study on the Pressure Continuity Residual for the Stabilization of Pressure in Incompressible Materials (비압축성 물체의 압력해 안정화를 위한 압력연속여분치의 매개변수 연구)

  • 이상호;김상효
    • Computational Structural Engineering
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    • v.8 no.4
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    • pp.189-198
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    • 1995
  • The conventional finite element formulations for incompressible materials show pressure oscillations or pressure modes in four-node quadrilateral elements of commonly used displacement and pressure interpolations. The criterion for the stability in the pressure solution is the so-called Babugka-Brezzi stability condition, and the above elements do not satisfy this condition. In this study, a pressure continuity residual based on the pressure discontinuity at element interfaces is used to study the stabilization of pressure solutions in bilinear displacement-constant pressure four-node quadrilateral elements. This pressure residual is implemented in Q1P0 element derived from the conventional incompressible elasticity. The pressure solutions can be stable with the pressure residual though they exhibit sensitivity to the stabilization parameters. Parametric study for the solution stabilization is also discussed.

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A Study on Controlled Blasting Design in Construction Field (건설현장에서의 제조 발파 설계에 관한 고찰)

  • 이화창
    • Explosives and Blasting
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    • v.14 no.1
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    • pp.49-63
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    • 1996
  • Blasting is a work that destruct an object by use of explosive. Its use covers a wid range, and it is applicable to blast the rocks, minerals, coal, steel and concrete structures, bridges, etc. To execute the blast plan most effectively, the properties of the object and the explosives should be well understood, and all the other conditions must ve incorporated in its design and plan. A safe blasting pattern and procedure should be selected considering the envirinmental effects and dther conditions. At the same time, a protective protective pricedures should be utilized to prevent the safety hazards such as the excessive blast vubration, air pressure, and the flying fragments. This study reviews the controlled blasting techniques in these regards.

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Image Noise Removal using State Estimation Filter (상태 추정 필터를 이용한 영상 잡음 제거)

  • Jang, Hoon-Seok
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.15 no.4
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    • pp.237-242
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    • 2022
  • Acquiring high-quality images in control and measurement systems is one of the important factors. Among image acquisition technologies, SFF (Shape from Focus) is a technology for recovering a 3D shape by acquiring 2D images with different focus levels by moving an object at a predetermined step size along the optical axis. For SFF, when an object is moved at a constant step size, mechanical vibration, referred as jitter noise, occurs in each step along the optical axis. In this paper, a new state estimation filter is designed and applied for reducing the jitter noise. For the application of the proposed method, the jitter noise and focus curves are modeled as Gaussian function. Experimental results demonstrate the effectiveness of proposed method.

Work path planning of 6-DOF excavator based on multi-body dynamics model (다물체 동역학 모델 기반 6 자유도 굴삭기의 작업 경로 계획)

  • Dae Ji Kim;Joo Young Oh;Hyune Jun Park;Jintai Chung;Chang Heon Song
    • Journal of Drive and Control
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    • v.21 no.4
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    • pp.161-173
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    • 2024
  • This study aimed to plan a work path for a 6-DOF excavator and evaluate the applicability of reinforcement learning. The excavation work caused vibrations in main components of the tilt-rotator, which were experimentally measured. Weak components were identified through vibration experimental and signal processing. Next, a multi-body dynamics model correlated with vibration data was used to generate a stress data set for weak components. After that, various excavator agents were compared in a reinforcement learning environment and the validity of applying the stress data set was verified. Finally, this study analyzed work path planning derived from reinforcement learning and discussed results. Results of this study can be used as basic data for developing operating guides and operating assistance systems to help existing equipment users operate their equipment more safely and efficiently.

A Study on the Vibration Analysis for the Composite Multi-axial Optical Structure of an Aircraft (항공기용 복합재료 다축 광학 구조의 진동해석에 관한 연구)

  • Kim, Dae-Young;Kwak, Jae-Hyuck;Lee, Jun-Ho;Park, Kwang-Woo;Jeong, Kwang-Young;Cheon, Seong-Sik
    • Composites Research
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    • v.24 no.2
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    • pp.14-21
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    • 2011
  • In this paper, a dynamic model is proposed for multi-axis optical structure of an aircraft. Modal analysis, sine-wave analysis, and random vibration analysis are done using a multi-body dynamic program for the multi-axis optical structure. By applying Al 6061-T6 and two types of CFRP to the camera module, x, y, and z responses are found and compared according to each axis excitation. The results will be used for reducing the weight of the camera module.

Structure Borne Noise Analysis of a Flexible Body in Multibody System (다물체계내 유연체의 구조기인 소음해석)

  • 김효식;김창부
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.11
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    • pp.882-889
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    • 2003
  • This paper presents the method for structure borne noise analysis of a flexible body in multibody system. The proposed method is the superposition method using the flexible multibody dynamic analysis and the finite element one. This method is executed in 3 steps. In the 1st step, time dependent quantities such as dynamic loads, modal coordinates and gross body motion of the flexible body are calculated through a flexible multibody dynamic analysis. And frequency response functions of those time dependent quantities are computed through Fourier transforms. In the 2nd step, acoustic pressure coefficients are obtained through structure-acoustic coupling analyses by the finite element method. In the final step, frequency responses of acoustic pressure at the acoustic nodes are recovered through linear superposition of frequency response functions with acoustic pressure coefficients. The accuracy of the proposed method is verified in the numerical example of a simple car model.

A Study on Vibration Characteristics of Engine Mount System of a Medium Duty Truck at the Key On/Off (중형트럭 시동 시 엔진마운팅 시스템의 진동 특성 연구)

  • Kuk, Jong-Young;Lim, Jung-Hwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.4
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    • pp.97-102
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    • 2008
  • The vibration of a vehicle, which is caused by and transmitted from the engine, has significant effect on the ride comfort and the dynamic characteristics of the engine mount system have direct influence on the vibration and noise of the vehicle. This paper examines the body shake caused by the engine excitation force on engine key on/off of a medium truck by experiment and simulation. The analysis model consists of the engine, a body including the frame, front and rear suspensions and tires. The force element between the body and the suspension is modeled as a combination of a suspension spring and a damper. The engine shake obtained from the experiment was compared with the result of the computer simulation, and by using the verified computer model, parametric study of the body shake on engine key on/off is performed with changing the stiffness of an engine mount rubber, the engine mount angle, and the position of engine mounts.

A Study on the Vibration Analysis and Optimization for the Composite Optical Structure of an Aircraft (복합재료를 적용한 항공기용 카메라 구조 경량화 설계 및 최적조건 선정에 관한 연구)

  • Kim, Byeong-Jun;Lee, Jun-Ho;Lee, Haeng-Bok;Jung, Dae-Yoon;Cheon, Seong-Sik
    • Composites Research
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    • v.25 no.6
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    • pp.230-235
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    • 2012
  • This paper presents the vibration characteristics and the optimization using the orthogonal array about applied composite optical structure of an aircraft. To acquire the vibration characteristics for stable line of sight, modal analysis are performed by using multi-body program ADAMS. And to optimize optical structure, for design variables were selected, larger-the-better characteristics were considered using results of S/N ratio and orthogonal array L9(34). When bearing constraints are selected, radial, axial and moment stiffness value are used to analysis for optimization until now. But B.S.R which is non-dimensional parameter is proposed, structures including bearings can be used for optimization. And then having a result of lager-the-better, the optimized values of each design variable were successfully suggested.

Measurement of Vibration Mode Shapes Using Time Average ESPI (시간 평균 ESPI를 이용한 진동 물체의 모우드 형태의 계측)

  • Kang, Young-June;Choi, Jang-Seob
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.2
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    • pp.84-93
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    • 1996
  • Non-destructive inspection techniques using laser have been broading their application areas as well as growing their measurement skills together with the rapid development of circumferential technology like fiber optics, computer and image processing. The ESPI technique is already on the stage of on-line testing with commercial products in developed country nations. Especially, this technique is expected to be applied to the nuclear industry, automobile and aerospace because it is proper for the vibration measurement and it can be applied to objects of a high temperature. This paper describes the use of the ESPI system for measuring vibration patterns on the reflecting objects. Using this system, high-quality Jo fringes for identifying mode shapes are displayed. A bias vibration is introduced into the reference beam to shift the Jo fringes so that fringe shift algorithms can be used to determine vibration amplitude. Using this method, amplitude fields for vibrating objects were obtained directly from the time-average interferograms recorded by the ESPI system.

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Dynamic Analysis of a Linear Feeder for Uniform Transformation of Grains (곡물의 균일한 이송을 위한 리니어 피더의 동특성 해석)

  • Lee, Kyu-Ho;Kim, Syung-Hyun;Chung, Jin-Tai
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.11
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    • pp.1069-1076
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    • 2007
  • The purpose of this study is to improve the performance of a linear feeder that can transport grains uniformly. In order to analyze the dynamic behaviors of a linear feeder, the displacements of the feeder are measured by several accelerometers when it is in an operating condition. After the signal data from the accelerometers are captured in the time domain, the feeder motion in the space is visualized by using graphic computer software. In addition, a dynamic model of the feeder is established for a multi-body dynamics simulation. For the dynamic simulation, RecurDyn, which is a commercial multi-body dynamic package, is used. From the experimental and the computational approaches, an optimal dynamic motion is obtained for uniform transportation of grains. Furthermore, we also consider the determination of design parameters for optimal dynamic motion such as centroid, stiffness, and damping coefficient of the feeder system.