• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11b
• /
• pp.576-581
• /
• 2002

The suspension is a structure that supports reading, writing head in information storage device. In order to develop the information storage device of high track density, it is necessary to study about the suspension. To satisfy operation condition of information storage device, the suspension shape is very important since it correlates to dynamic characteristics. Therefore, it is necessary to analyze the dynamic characteristics by using finite element analysis and to optimize the suspension of information storage device using size optimization and topology optimization. The suspension has various modes according to different kinds of frequency bandwidth. Sway mode and second torsion mode are especially critical among them. In this paper, we investigated method to improve bandwidth of sway and second torsion mode of HDD and ODD suspension by using size optimization and topology optimization.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.1112-1117
• /
• 2003

Polarized Fourier transform infrared (IR) absorption is used to probe molecular conformation in a ferroelectric liquid crystal (FLC) during the reorientation induced by the external field. Spectra of planar aligned cells of FLC W314 are measured as functions of IR polarizer orientation and electric field applied to the FLC. The time evolution of the dichroism of the absorbance due to biphenyl core and alkyl tail molecular vibration modes, is observed. Static IR dichroism experiments show a W314 dichroism structure in which the principal axis of dielectric tensor from molecular core vibration are tilted further from the smectic layer normal than those of the tail. This structure indicates the effective binding site in which the molecules are confined in the Sm-C phase has, on average, "zig-zag" shape and this zig-zag binding site structure is rigidly maintained while the molecular axis rotates about the layer normal during field-induced switching.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.12
• /
• pp.1090-1095
• /
• 2013

This paper describes the FEM analysis for squeak problem of the ceramic-on-ceramic hip joint system. The onset of hip squeak is estimated by the positive real parts of the eigenvalues in the hip joint system. From the complex eigenvalue analysis, the unstable frequencies and the corresponding mode shapes are determined at the certain severe friction coefficients. It is found that some bending and torsion modes of the femoral stem can be unstable due to the mode-coupling mechanism. It also shows that the magnitude of the friction coefficient plays a key role on the occurrence of hip squeak.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.1168-1173
• /
• 2001

Compressors are the main source of noise of refrigerators and air-conditioning unit. Recent studies on the sound propagation of rotary compressors showed that the accumulator is a significant source of noise generation. This paper describes a design change of a rotary compressor for noise reduction using topology optimization. Topology optimization has been developed and used to find the most effective structural configuration in the early stage of design procedures. FE model of the rotary compressor composed of all the components is built for the topology optimization. Topology optimization results show that the empirical design for the present structure fail to constrain some resonance modes and a new component is required.

• Structural Engineering and Mechanics
• /
• v.60 no.1
• /
• pp.149-162
• /
• 2016

Structure-dependent integration methods seem promising for structural dynamics applications since they can integrate unconditional stability and explicit formulation together, which can enable the integration methods to save many computational efforts when compared to an implicit method. A newly developed structure-dependent integration method can inherit such numerical properties. However, an unusual overshooting behavior might be experienced as it is used to compute a forced vibration response. The root cause of this inaccuracy is thoroughly explored herein. In addition, a scheme is proposed to modify this family method to overcome this unusual overshooting behavior. In fact, two improved formulations are proposed by adjusting the difference equations. As a result, it is verified that the two improved formulations of the integration methods can effectively overcome the difficulty arising from the inaccurate integration of the steady-state response of a high frequency mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.480-485
• /
• 2004

If a wall separates the bounded and unbounded spaces, then the wall's role in transporting the acoustic characteristics of the two spaces is not well defined. In this paper, we attempted to see how the acoustic characteristical of two spaces are really affected by the spatial characteristics of the wall. In order to understand coupling mechanism, we choose a finite space and a semi-infinite space separated by the flexible or rigid wall and an opening. A volume interaction can be occurred in structure boundary and a pressure interaction can be happened in the opening boundary. For its simplicity, without loosing generality, we use rather simplified rectangle model instead of generally shaped model. The source impedance is presented to the various types of boundaries. The distributions of pressure and active intensity are also presented at the cavity and structure-dominated modes. The resulting modification, shifts of mode1 frequencies and changing of standing wave patterns to satisfy both coupled boundary conditions and governing equations, are presented.

• Journal of Advanced Marine Engineering and Technology
• /
• v.11 no.1
• /
• pp.63-71
• /
• 1987

The measuring of acoustic intensity has been investigated by many researchers and practicians during the last several decades. But due to the lack of measurement accuracy, they have had no practical use. In recent years, the two microphone acoustic intensity method has been developed by the advancement of FFT analysis technique and the digital data processing equipment. This new method of using two microphones gives informations on the noise source survey and the acoustic power of sound radiation source without the anechoic room. In this paper, theoretical formulae for the two microphone acoustic intensity method and the sound transmission loss are checked. The obtained results for the acoustical enclosure of gas heat pump were compared with the classical field incidence mass law. The surface vibration modes for a panel of enclosure were also estimated.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.10a
• /
• pp.90-95
• /
• 2000

This study is to choose the most proper model for AGV throughout simulation of behavior of suspension to reduce trial and error because there is no AGV treating heavy weight at harbor loading and unloading at home. Therefore, we estimate the vibration modes of the various suspension applied to AGV, which is over 75 ton included the weight of two containers on 5G using the Matlab, one of the simulation programs

• Journal of the Korean Chemical Society
• /
• v.29 no.3
• /
• pp.205-212
• /
• 1985

By using the Mass-Weighted-Cartesian coordinate method, the allosteric effect of 2,2'-bipyridyl crown(4) ether is studied. The vibrational modes of 235, 234, 188, and 178cm$^{-1}$ belong to the pore opening motion of crown ether and those of 168, 104, and 67cm$^{-1}$ belong to the rotational vibration motion of bipyridyl. Especially the mode appearing at 178cm$^{-1}$ shows a large allosteric effect by activation of the allosteric site.

• International Journal of Safety
• /
• v.5 no.2
• /
• pp.1-5
• /
• 2006

A data acquisition and processing system for measuring the current collection signals of the Korean High-speed Railway is developed. The current collection system is composed of a pantograph and the overhead catenary that supplies electrical power to the train through the pantograph. The system simultaneously measures the signals generated at the interface between the catenary and the pantograph through the accelerometers, load cells and strain gauges placed at various locations. The on-track test data are processed to evaluate the current collection reliability. The fiequency analysis of the signals reveals the presence of several structural vibration modes in the pantograph, as well as the components arising from the periodicity in the structure of the catenary and pantograph at the interface. The feasibility of predicting the contact performance from the measured signals is also demonstrated.