• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.137-140
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• 2003

Recently, as the demand of small-sized precision parts is rising in precision industry such as mobile, automobile, optic. etc. the requirement of small-sized machine tool is increasing. Desktop machine tool define small-sized machine tool that is able to install in table. According to diminishing in size, Desktop machine tool is able to economize production cost by reducing work area and consuming electric power. But Desktop machine tool generates vibration in acceleration and deceleration modes by inertia force of moving part. Also vibration is generated when it move simultaneously two axis or three axis. Such generating vibration situation is reason of declining stiffness of machine tool structure because of smallizing in size. And this vibration has a large effect on precision of machining products. Therefore, evaluating of the control characteristic is necessary for minimizing vibration of machine tool as much as possible to accomplish precision machining of small-sized parts

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2225-2235
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• 2004

An observatory termed 'Steel Swing' has been developed, where a 15000 kg pendulum is hanged from a stiff steel frame. A building element can be tested after inserted between the pendulum and the frame. Free vibration, forced vibration tests and earthquake monitoring were performed on an exposed-type steel column base. The response records monitored during natural earthquakes were used to identify the vibration property of the specimen. Identified system gain was approximated by a theoretical gain of linear SDOF system, and the response calculated based on such a linear system agrees with the monitored response fairly well. This research technique can be applied to check the behaviors of new materials and new details of connections and the safety of non-structural elements as well.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.1035-1041
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• 2005

Dynamic characteristics of CD/DVD deck fur vehicle are analyzed in this paper. Generally CD/DVD deck for vehicle is used from inferior environment with the vibration of the vehicle, shock of outside and so on. Therefore it must have the structure which is stabilized from the vibration to prevent read error. For this purpose, vibration characteristic of the deck for vehicle should be identified. To analyze characteristic of the deck system, we perform the signal analysis and modal testing using the EFT analyzer. Also we change the design factor degrading the performance of the deck system and verify the efficiency improvement using the acceleration measurement occurring to the sound discontinuation.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.327-329
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• 2000

This paper present the characteristic improvements of one-coil coin type vibration Motor. Rotor is consist of coreless coil and 4 segment commutator. Magnet is 4 pole, z direction magnetized. This one-coil coin type vibration motor has simple mechanical structure and good efficiency. So production cost is lower than other having 2 or more coils coin type motor but it has the weak points. That is small vibration magnitude and dead zone. Modifying the shape of rotor, vibration magnitude is increased. To avoid the dead zone we attached more magnetic body on rotor. As result we show the optimal position of magnetic body.

• Journal of KSNVE
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• v.7 no.4
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• pp.597-604
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• 1997

Ground vibrations induced from railroad were measured to get the basic data that can be usde to prepare countermeasures for solving environmental vibration problems. Vibration levels were measured simultaneously at three points in double distances from railroad. These data were analuzed with the kinds of trains, media to understand the magnitudes and characteristics of distance attenuation of railroad vibrations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.321-321
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• 2009

This paper presents quasi-zero-stiffness (QZS) characteristic of a passive isolator using flexures under compression force. The passive isolator consists of a positive stiffness element (a vertical coil spring) and a negative stiffness element (flexures under compression force), and their proper combination of the positive and negative stiffness elements can produce both substantial static and zero dynamic stiffness, so called QZS. Firstly, a nonlinear dimensionless expression of a flexure under compression force is derived. A dynamic model of the passive isolator is developed and numerical simulations of its time and frequency response are performed. Then, undesirable nonlinear vibration is quantified using a period doubling bifurcation diagram and a Poincare's map of the isolator under forced excitation. Finally, experiments are performed to validate the QZS characteristic of the passive isolator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.551-554
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• 2005

This study uses a characteristic function to explain correlations between the objective function and design variables. Analysis of means and table of orthogonal array were carried out. The change of shape of diaphragm, thickness of diaphragm and voice coil weight based on the table of orthogonal array is made. Therefore this study carried to decide shape of diaphragm, voice coil weight and thickness of diaphragm for minimizing 1st natural frequency and maximizing 2nd natural frequency of diaphragm using design of experiments and characteristic function with constraints. we showed improved design factors that minimized 1st natural frequency and maximized 2nd natural frequency of diaphragm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1433-1437
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• 2005

Until now, strain gage technique and accelerometer for the diagnosis safety of constructions are used widely. However, the limits of these methods are revealed. But Electronic Speckle Pattern Interferometry(ESPI) that uses Pulse Laser is noncontact, whole-field, real-time measuring method also dull to disturbance and can achieve test result in a very short time. It has various strong point in spot application, swift establishment, and dynamic conduct analysis for the entire field of Laser illuminate. This author analyzed vibration characteristic of using the Pulse ESPI System, the diagnosis safety of bridges, to simplify the analysis of the dynamic conduct of a large construction.

• Journal of Ocean Engineering and Technology
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• v.17 no.3 s.52
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• pp.21-26
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• 2003

An iteractive Kantorovich method is presented for the vibration analysis of rectangular orthotropic thick plates. Mindlin plate characteristic functions are derived in general forms using the Kantorovich method. Initially, Timoshenko beam functions consistent with the boundary conditions of the plate were used. Through numerical calculations of natural fairs of appropriate models, it has been confirmed that the method presented is superior to the Rayleigh-Ritz analysis or the finite element analysis in both accuracy and computational efficiency.

• Journal of Aerospace System Engineering
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• v.5 no.2
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• pp.33-39
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• 2011

The vibration characteristic of tires is one of very important issues which heavily affect the noise and comfort on driving. Therefore, when the new tire is designed, the vibration characteristic of tire should be considered. In this paper, the vibration characteristic of non-pneumatic tire is investigated for geometric of NPT which is designed by cell angle of spoke. The analysis is based on the finite element method and used ABAQUS program, which is able to non-linear analysis. The material of NPT is used for the Ogden energy model, which is model of hyperelastic material. This paper investigate natural frequency and modal of NPT and compare result of NPT with it of pneumatic tire.