• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.39.4-39
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• 2002

This paper presents a design and implementation of a PID feedback control loop for micro gyroscope. The feedback control loop improves the gyroscope performance such as linearity, bandwidth, and bias stability for micro gyroscope which is basically a high-Q system and exhibits a low performance with an open loop control. The designed and implemented feed-back control loop is applied to the SNU-Bosch MEMS gyroscope to demonstrate the improvement with the feedback control loop. The bandwidth is improved to 60Hz from 25Hz of open loop control. The linearity becomes 0.5% from 1%. The bias stability is improved to 0.03 deg/sec from 0.06 deg/sec.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.3
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• pp.20-31
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• 2005

The contents of mobile phones are rapidly appended and the structures are being changed substantially. Most of the problems with mobile phones are related with the vibrations and the displacements of PCB boards. In this study, the vibration magnitudes of the boards by impulses on the case are analyzed with the variations of the selected design parameters. The result shows that the extensive suppression of the vibrations are feasible by the proper selection of the design parameters. Also the suggested relationships between the parameter selections and the magnitudes of vibrations can be applied to establish a database for improved stability of the mobile phone structure which is a critical concern considering the short life span of the mobile phone models.

• Journal of the Korean Wood Science and Technology
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• v.25 no.1
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• pp.50-55
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• 1997

This study was carried out to utilize old newspaper(ONP) and paper sludge more effectively, and also to elucidate the influences of pressing conditions on the medium density fiberboard(MDF) properties. MDFs were made from ONP and low grade of paper sludge by wet process with change of pressing time, temperature and pressure. MDFs of ONP were more affected by pressing conditions, especially pressing pressure, but temperature and pressing time were also important. According to mixing paper sludge to ONP tensile and bending strength of MDF were decreased, but density and dimensional stability were improved. These results indicated that some physical properties of MDF can be improved by paper sludge and it is possible to use it in MDF.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.145-150
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• 1999

We have studied on the tribological characteristics of surface modification by Arc Ion Implantation(AIP) coating method. Coating materials were deposited by the Titanium carbide(TiC) and Titanium nitride(TiN). An experimental process was established to determine the tribological characteristics of friction and wear behaviour with the variation of applied load, temperature and the time by the Falex friction and wear test machine. The results, It can be improved that when the surface modification of hard coatings(TiC, TiN) was deposited steel, the tribological characteristics become better. It is argued that improved because of excellence of the anti-wear, the extreme pressure properties and the heat stability.

• Journal of KSNVE
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• v.3 no.4
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• pp.383-394
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• 1993

An automotive suspension system generally behaves like a low frequency band-pass filter(0.5 - 10 Hz). Passengers are very sensitive to this frequency range in terms of ride quality and road holding ability. In this paper, a LQG/ LTR controller is suggested to improve the ride quality and road holding ability in the specified frequency rage. It has been found by numerical simulation that the ride quality and road holding ability can be improved in the frequency ranges of 0.5 - 3.0 Hz and 0.3 - 2.1 Hz respectively. In addition, a new approach using root locus to evaluate the stability robustness of the active suspension system is studied. It is shown that the stability robustness of the LQG/LTR controller designed in this paper is improved, compared to the passive system.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.25-28
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• 2002

In the coarse grain HAZ adjacent to the fusion line, most of the TiN particles in conventional Ti added steel are dissolved and austenite grain growth is easily occurred during welding process. To avoid this difficulty, thermal stability of TiN particle is improved by increasing the nitrogen content in steel. In this study, the effect of hlgh nitrogen TiN particle on preventing austenite grain growth in HAZ was investigated. Increased thermal stability of TiN particle is helpful for preventing the austenite grain growth by pinning effect. High nitrogen TiN particle in simulated HAZ were not dissolved even at high temperature such as 1400'E and prevented the austenite grain growth in simulated HAZ. Owing to small austenite grain size in HAZ the width of coarse grain HAZ in high nitrogen TiN steel was decreased to 1/10 of conventional TiN steel. Even high heat input welding, the microstructure of coarse grain HAZ consisted of fine polygonal ferrite and pearlite and toughness of coarse grain HAZ was significantly improved.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.549-551
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• 1998

This paper deals with the new gait implementation of biped walking robot(IWR-III). In the case of using old gait. The trunk should be stopped during the phase changing time. But using new gait, the trunk moves continuously for all walking time. As a result, IWR-III has a walking gait similar to human being, and the motion of balancing joints can be reduced by the trunk ahead effect in the double support phase, moreover, ZMP tracking is improved, therefore the stability of IWR-III is improved. The trajectory is planned with a 5th order spline interpolation and stability of IWR-III is certified with a biped simulator.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.88-92
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• 2019

Automotive industry requires high technologies to stabilize apparatuses for the EGR valve manufacturing. Vibrations of washing machine are one of the most critical factors for causing unwashed products, which are the main reasons of the defects.In this study, the structure of the washing machine was analyzed through the experiment and the computer simulation to investigate the main reasons of the vibrations, and further to alter the design for the improved stability. And the design alterations were applied to the machine to identify the effects of those alterations.The result of the study shows that design alterations of the washing machine can effectively suppress about 85% of the vibrations, and further can minimize the unwashed EGR valve.

• Structural Engineering and Mechanics
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• v.27 no.1
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• pp.49-61
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• 2007

This paper presents a modified and improved bi-directional evolutionary structural optimization (BESO) method for topology optimization. A sensitivity filter which has been used in other optimization methods is introduced into BESO so that the design solutions become mesh-independent. To improve the convergence of the optimization process, the sensitivity number considers its historical information. Numerical examples show the effectiveness of the modified BESO method in obtaining convergent and mesh-independent solutions. A study of the effects of various BESO parameters on the solution is then conducted to determine the appropriate values for these parameters.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.14-18
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• 2021

Electric Vehicle industry requires high technologies to stabilize apparatuses for the Coolant heater manufacturing. Vibrations of Leak Machine are one of the most critical factors for causing delivered of the defective product or poor inspection, which are the main reasons of the defects. In this study, the structure of the Leak Machine was analyzed through the experiment and the computer simulation to investigate the main reasons of the vibrations, and further to alter the design for the improved stability. And that design alterations were applied to the machine to identify the effects of those alterations. The result of the study shows that design alterations of the Leak Machine can effectively suppress about 97.8% of the vibrations, and further can improving the Inspection precision of the Coolant heater.