• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.319.2-319
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• 2002

The main obstacle to high track density in HDD id the structural resonances of the suspension. The most critical mode is sway mode and second torsion mode, when a data is read and written. It is common fact that the effect of two modes is smaller when a thickness is bulky. But the stiffness of suspension is smaller, the slider can follow a disk better. Because these two fact are reciprocal, a compromise is needed. So we investigated another method to improve band width without changing of the thickness of suspension but with changing of the shape. (omitted)

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.242-244
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• 1987

Using the energy trapping theory and the acoustic coupling theory. the Bandpass filter(center frequency = 10.7 MHz) of the fundamental thickness mode was made from the composition of $Pb_{0.96}Sr_{0.04}(Zr_{0.53}Ti_{0.47})O_3$+ 1wt% $Fe_2O_3$. Also, in the double mode monolithic filter, It was observed that as decreasing the size of the electrodes, or shortening the gap between two electrodes, the percent frequency separation was increased. Based on these. a 10.7 MHz uniwafer filter was made having the characteristics that bandwidth was 700 KHz and the percent frequency separation was 6 [dB] and selectivity was 29 [dB], end spurious response was 24 [dB] and insertion loss was 7 [dB].

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.10
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• pp.484-490
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• 2003

This paper describes with the stator analysis and design of a ring type ultrasonic motor. The design for piezoelectric ceramic and elastic body of stator were calculated by using the finite element method (FEM) that consider the resonance frequency, vibration mode and coupling efficiency. Namely, such results were acquired the calculation result of the piezoelectric ceramic thickness 0.5[mm], elastic body thickness 2.0[mm], resonance frequency 51.8[kHz], vibration mode 7 order and coupling efficient 12.5[%], the outer and inner diameter of vibrator 50[mm], 38[m]. On the basis of such result, the ring type ultrasonic motor was manufactured. Also for driving characteristics of ring type ultrasonic motor, 2-phase inverter was constructed. Then the propriety of this paper was established from comparision of the simulation and an experiment results of the ring type ultrasonic motor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1163-1172
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• 2001

The two dimensional problem of a layered tribological system(TiN/Steel) containing a vertical surface breaking crack and subject to rolling contact is considered in this study. Using finite elements and stress extrapolation method, a series of preliminary models are developed. Preliminary results indicate that the extrapolation technique is valid to determine Modes I and II stress intensity factors for cracks. In the case of TiN/Steel medium, KI and KII were determined for variations in crack length, layer thickness, and load location. The results show that KII reaches maximum values when the contact is adjacent to the crack where Mode I stresses are compressive. KII values decrease with decreased crack length and significantly decrease for reduced layer thickness.

• 전기의세계
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• v.28 no.4
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• pp.47-52
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• 1979

Total number of resonant modes in a microwave oven cavity may be maximized for a given frequency bandwidth to obtain more uniform power distribution by choosing proper size of the cavity. The total number of modes is calculated for a dielectrically loaded rectangular cavity and its size is suggested here for which the change in the number of modes is less sensitive to the change of dielectric layer thickness and its total number of modes is maximized in a given range of cavity sizes. A prove coupled rectangular cavity is constructed and the total existing modes are measured to see the change of modes depending on the dielectric layer thickness and the cavity size. Surface wave mode existing in the dielectric layer is confirmed by measuring Q and the input impedance of the cavity for this mode, which closely compares with the calculation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.485-486
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• 2005

Fringe-field switching mode which has a horizontal and vertical electric field exhibits high transmittance and wide viewing angle characteristics. In the FFS mode, a passivation layer between common and pixel electrodes exists, which functions as preventing current leakage of fringe-field. In this paper, we have studied LC behavior, transmittance and operating voltage characteristics with applied voltage as a function of the passivation layer thickness and defined optimal value of the layer to be about $0.5{\mu}m$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.690-695
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• 2005

We have investigated on the development of 2-2 mode piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the electrical properties and acoustic impedance of 2-2 mode piezocomposite which were fabricated using the dice-and-fill technique for the different volume fractions of PZT The volume shrinkage of polymer is an important factor in 2-2 mode piezocomposites fabrication. The thickness mode electromechanical coupling factor($\kappa_t$) of PZT was compared with that of piezocomposites. It was shown that the 2-2 mode piezocomposites were much better than the PZT only. The acoustic impedance of 2-2 mode piezocomposites decreased linearly when PZT volume fraction was decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.589-594
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• 2009

We have studied electro-optic characteristics as a function of passivation thickness existing between common electrode and pixel electrodes in the fringe-field switching (FFS) mode using the LC with positive dielectric anisotropy. A steep increase in the transmission is observed with increase in the passivation layer from $0.29{\mu}m$ to $1.09{\mu}m$ and thereafter it almost saturates over the $1.09{\mu}m$ of passivation layer. This saturation is mainly associated with correlation between transmittance at the center region of pixel electrode and at the center region between pixel electrodes. From the results, optimal thickness of passivation layer can be defined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.820-823
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• 2000

The characteristics of wire deflection, surface roughness and roundness were observed on changing discharge time for electrical discharge machining(EDM) of tungsten carbide in various conditions of thickness. The wire deflection was decreased as increasing discharge time and wire tension, the gap of deflection was decreased after thickness 60mm and discharge time of 6$\mu\textrm{s}$ due to the changing from fundamental mode to vibration mode. The deflection is the smallest at the water specific resistivity of 7.5 kΩ ㆍcm. The deflection is found to be decreased as increasing dwell time, and the result is due to the vibration of the pressure and the amount of the dielectric. The component of copper(Cu) and zinc(Zn), which is the main material of wire electrode, was observed for rough wire-cutting EDM of STD-11. This phenomena is found to be decreased as the number of EDM is increased. But it will be improved by changing the material and the shape of wire. The roundness of middle is found to be worse than that of upper and it is increased as the thickness of material is increased.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.31-37
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• 2004

We have proposed a design methodology for large active-area single-mode VCSELS, which have higher reliability and output power, and are well-suited for high-speed operation. The key idea underlying the design methodology is to reduce the effective index difference between active and cladding regions by controlling the thickness and position of the oxide layer. The idea is confirmed by the self-consistent effective index method. By placing the oxide layer position properly, we can increase the radius of the oxide aperture for single-mode operation by 3 times.