• 한국음향학회지
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• 제43권4호
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• pp.391-399
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• 2024

란주반 트랜스듀서에 의해 강제 진동되는 원형 진동판으로부터 방사되는 음장의 분포를 해석하기 위하여 L. Rayleigh에 의해 도출된 진동 원판의 운동방정식을 기초로 구동 영역 및 고정 경계영역의 경계 조건을 적절히 적용하여 이론적 해석모델을 도출하였다. 도출된 해석모델을 이용하여 진동 원판의 표면에 분포하는 진동 변위를 계산하고 이로부터 방사되는 초음파에 의해 형성되는 음장을 계산한 결과, 진동 원판의 넓이에 따라 방사 특성이 크게 변함을 확인할 수 있었다. 비교를 위하여 유한요소법인 COMSOL 프로그램을 사용하여 동일한 시스템에 대한 시뮬레이션을 수행한 결과 이론 계산 결과와 좋은 일치를 보여 본 연구에서 도출한 이론적 해석모델의 유효성을 확인할 수 있었다. 본 연구에서 도출한 이론적 해석모델은 초음파 화학분야 등 관련 디바이스의 설계 및 개발에 활용될 수 있을 것으로 기대된다.

• Coupled systems mechanics
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• 제8권3호
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• pp.199-218
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• 2019

This paper studies the forced vibration of the hydro-elastic system consisting of the anisotropic (orthotropic) plate, compressible viscous fluid and rigid wall within the scope of the exact equations and relations of elastodynamics for anisotropic bodies for describing of the plate motion, and with utilizing the linearized exact Navier-Stokes equations for describing of the fluid flow. For solution of the corresponding boundary value problem it is employed time-harmonic presentation of the sought values with respect to time and the Fourier transform with respect to the space coordinate on the coordinate axis directed along the plate length. Numerical results on the pressure acting on the interface plane between the plate and fluid are presented and discussed. The main aim in this discussion is focused on the study of the influence of the plate material anisotropy on the frequency response of the mentioned pressure. In particular, it is established that under fixed values of the shear modulus of the plate material a decrease in the values of the modulus of elasticity of the plate material in the direction of plate length causes to increase of the absolute values of the interface pressure. The numerical results are presented not only for the viscous fluid case but also for the inviscid fluid case.

• 대한족부족관절학회지
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• 제17권2호
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• pp.130-135
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• 2013

Purpose: Preshaped Locking compression plate(LCP) has holes with fixed angle between screw and plate and have advantage firm fixation because it has stability of angular and axial deformity. We evaluated usefulness of LCP after open reduction and internal fixation in distal fibular fracture. Materials and Methods: Between December 2011 and May 2012, 23 patients with fracture of distal fibula were followed up at least 12 months underwent open reduction and internal fixation with LCP. There were 15 males and 8 females with a mean age 39.8(20~69) years. According to Danis-Weber classification, there were 20 cases of type B and 3 cases of type C. There were 13 cases of isolated lateral malleolus fractures, 1 case of bimalleolar fracture, 6 cases of trimalleolar fractures and 3 cases of distal tibia fractures with proximal fibula fracture. Intraoperatively, we assessed whether preshaped LCP fit lateral margin of distal fibula or not and evaluated quality of reduction and postoperative complications. The cases were analyzed by radiological bone union time and clinical results according to the criteria of Meyer Results: Of all cases, complete bone union was achieved and average radiological bone union time was 7.3(6~12) weeks. The clinical results were excellent in 18 cases(78%), good in 5 cases(22%). There were 5 cases of plate with 3 holes, 13 cases of plate with 4 holes, 2 cases of plate with 5 holes, 1 case of plate with 6 holes and 2 cases of plate with 7 holes. The average number of screws at proximal fragement was 2.5 and at distal fragment was 3.5. In 14 cases (60.8 %), we needed re-bending of plate because the distance between plate and lateral cortical margin of distal fibula was more than 5 mm at anteroposterior X-ray after reduction. All cases have anatomical reduction and there were no complications of wound infections. There were no complaint about hardware irritation. Conclusion: At fractures of distal fibula,preshaped LCP had a excellent stability although far cortex was not fixed with screw and bending of plate. And there are less complications of hardware irritation and wound problems. But, Some complement would be needed because there were no complete fitting between precontour of LCP and lateral cortical margin of distal fibula.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.5-8
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• 2000

This paper presents the results of an elastic buckling analysis of orthotropic plate under in-plane linearly distributed forces. The analytical solution for the orthotropic plate whose boundaries were assumed to be simply supported was derived in the previous work. In this study the loaded edges of plate are assumed to be simply supported and other two edges are assumed to be fixed. For the buckling analysis Rayleigh-Ritz method is employed. Graphical form of results for finding the elastic buckling strength of orthotropic plate under in-plane linearly distributed forces is presented.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2001년도 춘계 학술대회논문집
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• pp.134-143
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• 2001

Viscous solutions of supersonic jet impinging on a flat plate normal to the flow are simulated using three-dimensional Navier-Stokes solver. The jet impinging flow structure exhibits such complex nature as shock shell, plate shock and Mach disk depending on the flow parameters. Among others, the dominant parameters are the ratio of the nozzle exit pressure to the ambient pressure and the distance between the nozzle exit plane and the impinging plane. In the present study, the nozzle contour and the pressure ratio are held fixed, while the jet impinging distance is varied to illuminate the characteristics of the jet plume with the distance. As the plate is placed close to the nozzle at 3D high, the computed wall pressure at or near the jet center oscillates with large amplitude with respect to the mean value. Here D is the nozzle exit diameter. The amplitude of wall pressure fluctuations subsides as the distance increases, but the maximum pressure level at the plate is achieved when the distance is about 4D high. The frequency of the wall pressure is estimated at 6.0 kHz, 9.3 kHz, and 10.0 kHz as the impinging distance varies from 3D, 4D, to 6D, respectively.

• 로봇학회논문지
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• 제6권1호
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• pp.78-85
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• 2011

This article investigates kinematic characteristics of a Sch$\ddot{o}$nflies motion generator which represents a mechanism having translational three Degree-of-Freedom (DOF) and rotational one-DOF motion about a fixed axis. The mechanism consists of the base plate and the moving plate, and four identical limbs connecting them. Each limb employs two revolute joints (RR), one parallelogram (Pa), and two revolute joints (RR) from the base plate to the moving plate. The mechanism is driven by four actuators which are placed on the base plate to minimize dynamic loads. It is shown through simulations that the mechanism can be designed to secure large dexterous workspace and thus has very high potential for actual applications such as haptic devices and high-speed requiring tasks such as pick-and-place operations, riveting, screwing tasks, etc.

• 반도체디스플레이기술학회지
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• 제6권1호
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• pp.59-64
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• 2007

Non-contact transportation of a large-sized glass plate using air cushion for the vertical sputtering system of liquid crystal display (LCD) panel was considered. The objective of the study was to design an air pad unit which was composed of multiple injection and exhaust holes and mass flow supplying pipe. The gas was injected through multiple small holes to maintain the force for levitating glass plate. After hitting the plate, the air was vented through exhaust holes. Complex flow field and resulting pressure distribution on the glass surface were numerically studied to design the air injection pad. The exhaust hole size was varied to obtain evenly distributed pressure distribution at fixed diameter of the injection hole. Considering the force for levitating glass plate, the diameter of the exhaust hole of 30 to 40 times of the gas injection hole was recommended.

• Structural Engineering and Mechanics
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• 제6권4호
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• pp.427-437
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• 1998

Flat plate constructions are structural systems which are directly placed on columns without any beams. Various solution methods have been introduced for the solution of flat plate structures under horizontal and vertical loads. In most of these solution methods, models comprising of one column and one plate have been studied. In other solutions, however, co-behavior of two reciprocal columns has been investigated. In this study, interrelations of all the columns on one storey have been examined. At the end of the study structure consisting of nine columns and four plates has been chosen as a model. Then unit moment has been successively applied to each of these columns and unit moments carried over the other columns have been found. By working out solutions far plates and columns varying in ratio, carry-over factors have been found and these factors given in tables. In addition, fixed-end moment factors on the columns arising due to vertical load were also calculated. Then citing slope-deflection equations to which these results could be applied, some examples of moment and horizontal equilibrium equations have been given.

• 한국소음진동공학회논문집
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• 제11권9호
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• pp.462-474
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• 2001

In this paper, Generalized Differential Quadrature Method is applied to the buckling analysis of built-up columns without or with stay plates. numerical analysis using GDQM is carried out for various boundary conditions(simply supported conditions, fixed conditions, fixed-simply supported conditions), dimensionless stiffness parameter and dimensionless inertia moment parameter. The accuracy and convergence of solutions are compared with exact solutions of Gjelsvik to validate the results of GDQM. Results obtained by this method are as follows. 91) This method can yield the accurate numerical solutions using few grid points. (2) The buckling load of built-up column increases as the dimensionless stiffness parameter decreases. (3) The effects of boundary conditions on the buckling load are not considerable as the dimensionless stiffness parameter increases. (4) The buckling load of built-up column increases due to the stay plate.

• Current Photovoltaic Research
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• 제1권1호
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• pp.33-37
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• 2013

LCPV modules under 5 suns consist of reflective optics and receiver modules, similar to a typical fixed concentration PV module. If they are to be used as a compound parabolic concentrator, which is filled with a dielectric material, a compact plate structure of the fixed CPV can be designed and built at a large acceptance angle. These types of flat-$plate{\mu}$-LCPV modules are suitable for building integrated photovoltaic modules, facade applications, mobile devices, and small home appliances. Therefore, in this study, the possibilities for other application devices were studied and presented by designing and fabricating LCPCs for CPV modules.