• 산업경영시스템학회지
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• 제42권4호
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• pp.1-7
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• 2019

The customer of massage chair is expanding day by day from middle age to all ages. In 2018, the market size was 700 billion KRW, an increase of 30 times over 10 years. However, most related SMEs suffer from excessive competition by the market monopoly of some major companies. In this situation, in order for a related company to survive, it is necessary to steadily research and develop new products. Founded in 2009, company L produces massage chairs for health and relaxation of customers. L's products use a sound wave vibration module that is favorable for human body, unlike other products that use vibration motor type. However, frequent breakdowns of massage chair due to the vulnerability of plate (leaf) springs, which play an important role in sound wave vibration modules, made sap its competitiveness. In this paper, we propose a method to design desirable plate spring structure by sequentially experimenting with five different plate springs. The results of this study are expected to contribute to improve the quality of plate spring and the reliability of sound wave vibration module. In the future, it is necessary to find a way to use it in the development of foot massage or scalp management device as well as continuous research to find optimal plate spring structure through various analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.551-556
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• 2004

The theoretical method is developed to investigate the vibration characteristics of the combined cylindrical shells with an annular plate joined to the shell at any arbitrary axial position. The structural rotational coupling between shell and plate is simulated using the rotational artificial spring. For the translational coupling, the continuity conditions for the displacements of shell and plate are used. For the uncoupled annular plate, the transverse motion is considered and the in-plane motions are not. And the additional transverse and in-plane motions of the coupled annular plate by shell deformation are considered in analysis. Theoretical formulations are based on Love's thin shell theory. The frequency equation of the combined shell with an annular plate is derived using the Rayleigh-Ritz approach. The effect of inner-to-outer radius ratio, axial position and thickness of annular plate on vibration characteristics of combined cylindrical shells is studied. To demonstrate the validity of present theoretical method, the finite element analysis is performed.

• 소성∙가공
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• 제17권5호
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• pp.350-355
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• 2008

Currently, in the automotive industry, the efforts to reduce the manufacturing cost by changing the manufacturing process are continually performed. In this paper, we proposed a new manufacturing process, the roll bending process of a ring plate of automotive fuel tank instead of conventional press blanking process to reduce material loss and manufacturing cost. Finite element analysis was used to optimize the roll bending process to assure rectangular cross-section of the ring plate. Also, spring-back analysis after the roll bending process was performed and dimension of the bending die considering spring-back was analyzed. Finally, we verified a possibility for realization of the proposed method with prototypes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.311-315
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• 2008

Currently, in automobile industry. the efforts to reduce the manufacturing cost by changing the process of manufacturing are continually performed. In this paper, we proposed a new manufacturing process, the roll bending of a ring plate of automotive fuel tank instead of conventional press blanking process to reduce material loss and manufacturing cost. Finite element analysis was used to optimize the roll bending process to assure rectangular cross-section of the ring plate. Also, spring-back analysis after the roll bending was performed and dimension of the bending die considering spring-back was analyzed. Finally, we verified a possibility for realization of the proposed method shape with prototypes.

• Structural Engineering and Mechanics
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• 제16권3호
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• pp.341-360
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• 2003

The goal of this paper is to determine the eigenvalues of a uniform rectangular plate carrying any number of spring-damper-mass systems using an analytical-and-numerical-combined method (ANCM). To this end, a technique was presented to replace each "spring-damper-mass" system by a massless equivalent "spring-damper" system with the specified effective spring constant and effective damping coefficient. Then, the mode superposition approach was used to transform the partial differential equation of motion into the matrix equation, and the eigenvalues of the complete system were determined from the associated characteristic equation. To verify the reliability of the presented theory, all numerical results obtained from the ANCM were compared with those obtained from the conventional finite element method (FEM) and good agreement was achieved. Since the order of the property matrices for the equation of motion obtained from the ANCM is much lower than that obtained from the FEM, the CPU time required by the ANCM is much less than that by the FEM.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.626-633
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• 2000

An air spring which is a part of the railroad vehicle suspension system is used to reduce and absorb the vibration and the noise. Main components of the air spying are a cord reinforced rubber bellows, a upper plate, a lower plate and a stopper rubber spring. The characteristics of the air spring which are the load capacity, the vertical and the horizontal stiffness are depended on the configuration of rubber bellows, the angle of cord and the mechanical properties of cord. The computer simulation using commercial finite element analysis codes are executed to predict and evaluate the load capacity and the stiffness. The appropriate shape and cord angle of the air suing are selected to adjust the required performance of the air spring. Several samples of the air spring are manufectured and experimented. It is shown that the results by computer simulation are in close agreement with the test results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.416-418
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• 1996

A $50{\times}50{\mu}m^2$ aluminum micromirror array is fabricated using surface micromachining technology. $50{\times}50$ micromirrors are arrayed two dimensionally. The micromirror plate is supported by a vertical spring structure that is placed underneath the mirror plate. When the mirror plates reflect a light, the micromirror array un have large effective reflecting area. Fabrication of vertical spring uses only one mask and shadow evaporation process.

• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1246-1253
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• 2007

The recent issue of optical pickup actuators is to apply optical storage devices to mobile devices such as a cellular phone and PDA. It requires actuators to become smaller than conventional types. As the size becomes smaller, the magnetic force is reduced and the assembly of optical pickup actuators becomes more difficult. In addition, its dynamic characteristics are changed. In this paper, methods to improve magnetic forces and dynamic characteristics are suggested and the optimal result of the plate spring design is obtained. A diamond shape magnet and the fine pattern coil (FPC) are used to improve magnetic forces and damping elements are attached to decrease the peak magnitude of the mode instead of using structural damping, mostly for the purpose of improving the accuracy of the finite element simulation. To get more stable dynamic characteristics than conventional ones, a plate spring is applied to the optical pickup actuator and it is optimized with topology and parameter optimization to obtain the concept and the detail design, respectively.

• 항공우주시스템공학회지
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• 제14권6호
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• pp.18-25
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• 2020

This study investigated the structural behaviors and safety of an electro-mechanical linear actuator and a load simulator with a plate spring. The material and dimensions of the plate spring were determined by theoretically calculating the stress and torsional angle for the rating load of the actuator. Thereafter, a flexible multibody dynamics (FMBD) analysis was conducted on the linear actuator and load simulator to confirm the performance of the load simulator and acquire the reaction forces acting on the actuator and simulator. The structural safety of the linear actuator and load simulator was evaluated via finite element analysis using the aforementioned reaction forces. Consequently, the proposed linear actuator and load simulator were determined to be structurally safe; however, the safety factors for the actuation rod and the housing on the actuator were excessively high. Therefore, the weight and cost must be reduced to improve their design parameters in the future.

• 한국철도학회논문집
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• 제3권3호
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• pp.109-116
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• 2000

An air spring which is a part of the railroad vehicle suspension system is used to reduce and absorb the vibration and the noise. Main components of the air spring are a cord reinforced rubber bellows, a upper plate, a lower plate and a stopper rubber spring. The characteristics of the air spring which are the load capacity, the vertical and the horizontal stiffness are determined by the configuration of the rubber bellows, the angle of cord, and the mechanical properties of cord. Computer simulations using a commercial finite element analysis codes are executed to predict and evaluate the load capacity and the stiffness. The appropriate shape and cord angle of the air spring are selected to meet the required specifications of the air spring. Several samples of the air spring are manufactured and experimentally evaluated. It is shown that the results by computer simulation arc in close agreement with the test results.