• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.38-43
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• 1994

GaAs and AlGaAs layers were grown by Molecular Beam Epitaxy (MBE) to fabricate hith performance GaAs MESFETs. Optimum growth temperatures were found to be 600$^{\circ}C$ from their Hall measurement data. MESFETs with the gate legth of 1${\mu}$m and the gate width of 100.mu.m were fabricated on the MBE-grown GaAs layters which has i-GaAs buffer layer and characterized. Knee volgate and mazimum transconductance of the devices were 1V, 224mS/mm, respectively. Cut-off frequency at on-wafer measuring pattern was measured to be 18 GHz. The MESFET with the 1${\mu}$m -thick i-Al$_{0.3}Ga_{0.7}$As buffer layer between nactive and i-GaAs was fabricated on order to reduce the leakage current which flows through the i-GaAs buffer layer. Its output resistance was 2.26 k${\Omega}$.mm which increased by a factor of 15 compared with the MESFET without i-Al$_{0.3}Ga_{0.7}$As buffer layer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.457-462
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• 1987

Stochastic stability criterias for ocean wave analysis add simulation are studied using the data simulated by the linear superposition method. To clarify the criterias, the effects of the simulation parameters on the variance of stochastic properties of ocean waves are investigated, and the stable conditions of the parameters are estimated through the comparative study on the stochastic properties of simulated waves and well-known ocean waves. The simulation parameters considered are high frequency cut-off, data length, and number and phase angle of component waves. Statistical characteristics analysed are wave height, period and steepness, and the formation of groups of higher waves, resonance periods, steeper higher waves and extreme run-length of the run.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.5
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• pp.516-523
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• 2008

Centrifugal turbo blower is requested highly efficiency and low noise in FCEV, but the noise generated by this machine causes of the most serious problems in the NVH performance. In general, centrifugal turbo blower is dominated by mechanical noise and aerodynamic noise. Mechanical noise is generated by rotation of the bearing, misalignment and unbalance. And aerodynamic noise is generated by the strong intersection between the flow discharged from the impeller and the cut-off in the casing. The first object of this study is to comprehend a noise property of the blower through the noise test. And, second object is to bring up the method that can reduce blower noise.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.883-886
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• 2001

The mechanical properties such as the Young's modulus, damping ratio, vibration mode and hardness of the disk materials heat-treated under various conditions are measured, and the relations between there properties and the cutting characteristics such as early tip fracture are examined. The results obtained from this study are as follows. The circular saw with the V-Cr added disk has higher young's modulus and damping ratio than the saw with STC5 disk, preventing the early fracture of tungsten carbide due to the above properties. The circular saw with the disk which is subjected to the heat treatment at the quenching temperature of $830^{\circ}C$ and at the temperature of $550^{\circ}C$ have the best tool life and surface roughness.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.4
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• pp.381-386
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• 2013

A new resistance model for a Schottky Barrier Diode (SBD) in CMOS technology is proposed in this paper. The proposed model includes the n-well thickness as a variable to explain the operational behavior of a planar SBD which is firstly introduced in this paper. The model is verified using the simulation methodology ATLAS. For verification of the analyzed model and the ATLAS simulation results, SBD prototypes are fabricated using a $0.13{\mu}m$ CMOS process. It is demonstrated that the model and simulation results are consistent with measurement results of fabricated SBD.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.519-528
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• 2004

For reappearance of driving perception in a driving simulator, a washout algorithm is required. This algorithm can reappear the vehicle driving motions within workspace of the driving simulator. However classical washout algorithm contains several problems such as selection of order, cut-off frequency of filters, generation of wrong motion cues by characteristics of filters, etc. In order to overcome these problems, this paper proposes a new washout algorithm which gives more accurate sensations to drivers. The algorithm consists of an artificial inclination of the motion plate and human perception model with band pass filter and dead zone. As a result of this study, the motion of a real car could be reappeared satisfactorily in the driving simulator and the workspace of motion plate is restrained without scaling factor.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.239-242
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• 1999

In this paper, we report the process/device design of high-speed, high-voltage SOI smart power IC for mobile communication system, high-speed HDD system and the electronic control system of automobiles. The high voltage LDMOS with 70V breakdown voltage under 0.8${\mu}{\textrm}{m}$ design rule, the high voltage bipolar with 40V breakdown voltage for analog signal processing, the high speed bipolar with cut-off frequency over 20㎓ and LDD NMOS for high density were proposed and simulated on a single chip by the simulator DIOS and DESSIS. And we extracted the process/device parameters of the simulated devices.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.28-35
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• 1997

A novel high-Q vertical jinductor for MMICs is proposed and characterized in a wide range of frequencies (DC~10 GHz) using the numerical methods such as the PeEC(partial equivalent element circuit), the FDM (finite difference method) and the MoM (method of moments). Electrical superiority of the vertical inductor to the horizontal is observed in terms of the magnetic flux linkage and the ground screening effect. The veritcal bondwire inductor is designed in consideration of the wire bonding feasibility and the optimum electrical peformance. This structure is also analyzed using the equivalent circuit and compared with the conventional spiral inductors From the calculated results, high Q-factor, inductance, and cut-off frequency are observed to be inherent characteristics of the veritcal bondwire inductor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.402-406
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• 2000

In the Over-The-Range, the outlet size is limited by the industrial standards. Therefor to enlarge the volume of cavity, the installation height of ventilation fan is become small, the system resistance is higher than before. For that reason, the important design variables such as the diameter of a fan, the scroll expansion angle, etc. which play the significant role on flow rate and noise, are confined. In this study, we made an experiment of the diameter of fans relation to scroll expansion angle and investigated flow rate of the length of fans in enlarged cavity volume of OTR, and then we designed the new scroll to improve the flow rate and noise level. As a result, flow rate increased to 110% compared to current scroll and the blade passing frequency of a fan is disappeared by inclined cut-off shapes.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.136-141
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• 1995

GaAs power MESFETs with 1 .mu.m gate length and an undoped GaAs surface layer on the doped GaAs channel are fabricated using IR(image reversal) and air-birdge processes. And then We have measured and calculated DC and RF characteristics. We have obtained saturation current 107-500 mA (197-255 mA/mm), maximum linear RF output power 111-518.8 mW (204-270 mW/mm), current gain cut-off frequency 7-10 GHz, maximum unilateral transducer power gain 5.7-12.7, and power added efficiencies 37.9-41.2 % from the devices with gate width 0.45-2.2 mm, at 6 GHz.