• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2152-2154
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• 2004

A robust bending frequency tracker is proposed to design the adaptive notch filter which removes the time-varying missile structural mode from the sensor measurements. To design the bending frequency tracker, firstly, the signal model is derived from the input-output relationship of Nehorai notch filter structure. Also, the time-varying nature of the bending frequency is modelled as the norm-bounded uncertainty. Based on the uncertain signal model, it is shown that the design problem of robust bending frequency tracker can be casted into that of adaptive robust $H_{\infty}$ filter or equivalently robust LMS filter.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2477-2479
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• 2005

A robust bending frequency tracker is proposed to design the adaptive notch filter which removes the time-varying missile structural modes from the sensor measurements. To do this, the state-space form of a bending frequency model is derived under the assumption that the bending signal could be described as the lightly damped sinusoid. Since the resultant bending frequency model contains the parametric uncertainties in the measurement matrix, the design problem of bending frequency tracker is tackled by applying the robust Kalman filter to the model. This technique could be easily expanded to the multiple frequencies case because it newly illuminates the bending frequency tracking problem in view of general state estimation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.113-122
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• 2002

Control system modeling and optimal bending filter design for KSR-III (Korea Sounding Rocket III) are performed. Rigid rocket dynamics, aerodynamics, sloshing, structural bending, actuator dynamics, sensor dynamics and on-board computer characteristics are considered for control system modeling. Compensation for time-varying control system parameters is conducted by gain-scheduling. A filter to stabilize bending mode is designed using parameter optimization technique. Resultant attitude control system can satisfy required frequency domain stability margin.

• Tribology and Lubricants
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• v.38 no.3
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• pp.101-108
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• 2022

The structure and properties of tetrahedral amorphous carbon (ta-C) coatings depend on the main process parameters and bending angles of the magnetic field filter used in the filtered cathodic vacuum arc (FCVA). During the process, it is possible to effectively control the plasma flux of carbon ions incident on the substrate by controlling the arc discharge current, thereby influencing the mechanical properties of the coating film. Furthermore, we can control the size and amount of large particles mixed during carbon film formation while conforming with the bending angle of the mechanical filter mounted on the FCVA; therefore, it also influences the mechanical properties. In this study, we consider tribological characteristics for filtered bending angles of 45° and 90° as a function of arc discharge currents of 60 and 100 A, respectively. Experiment results indicate that the frictional behavior of the ta-C coating film is independent of the bending angle of the filter. However, its sliding wear behavior significantly changes according to the bending angle of the FCVA filter, unlike the effect of the discharge current. Further, upon changing the bending angle from 45° to 90°, abrasive wear gets accelerated, thereby changing the size and mixing amount of macro particles inside the coating film.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.406-412
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• 2014

In this study, flat-tubular-type alumina filters were manufactured using alumina powder of two sizes ($2.4{\mu}m$ ALM-44 and $0.4{\mu}m$ AP 400) by an extrusion process. The manufactured alumina filter was sintered at $1200-1600^{\circ}C$ for 1 h. As particle size increased, the largest pore size, average pore size and porosity increased; but density and linear shrinkage decreased. The alumina filter fabricated using ALM-44 powder sintered at $1500^{\circ}C$ was confirmed as the best water treatment filter after investigation of the bending strength, water permeability and impurity-removal efficiency of the experimental filters. This flat-tubular-type alumina filter is expected to be useful not only for direct water treatment, but also for use as a support filter during coating processes, to control pore size.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.440-443
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• 2010

This paper deals with the method of vibration measurement of a gun barrel structure using mechanical filter. When a bullet with high speed is moving within a gun barrel type structure with low bending vibration frequencies, it is difficult to measure the bending vibration signals of the structure. For example, noncontact type sensors such as displacement or velocity sensor are not appropriate for the measurement of vibrational signals because of the movement effect of the equipment frame through the moving structures or effect of the ground vibration. One of contact type sensors such as accelerometer is profitable for measurement of vibrational signals because of its wide measurement ranges. In the case of a gun barrel structure including high vibrational signals like shock waves, however, it is necessary to propose vibration measurement method filtering high frequencies. The purpose of the paper is to propose the proper vibrational measurement technique filtering high frequencies of a gun barrel type structure.

• Electrical & Electronic Materials
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• v.19 no.9
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• pp.28-32
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• 2006

A 7.0-inch transmissive type plastic TFT-LCD was developed at the resolution of 640 $\times$ 3 $\times$ 480 lines (114ppi). All of the processed of TFT, color filter and LC were carried out below $130^{\circ}C$ on PES plastic films. The process conditions of TFT, color filter and LC were optimized for large area TFT-LCD on plastic substrate. The backplane and the color filter was strongly adhered while the panel was bending by using holding spacers.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.40-45
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• 2022

In recent years, indoor air pollution has become a crucial environmental problem. Hence, the purification of indoor air is an important issue. Typical physical filters show relatively high dust collection efficiency at a dust particle size of more than 5.0 ㎛ but extremely low efficiency at an ultrafine size of less than 2.5 ㎛. In this study, an electric field filter was proposed to capture ultrafine dust with a size of less than 5.0 ㎛. Simulation results showed that the electric field filter effectively removed ultrafine dust. In addition, sufficient dust collection efficiency was obtained even with a simple plate-shaped filter without bending the Chevron filter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.181-184
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• 2007

This paper deals with the method of vibration measurement of a gun barrel structure using mechanical filter. When a bullet with high speed is moving within a gun barrel type structure with low bending vibration frequencies, it is difficult to measure the bending vibration signals of the structure. For example, noncontact type sensors such as displacement or velocity sensor are not appropriate for the measurement of vibrational signals because of the movement effect of the equipment frame through the moving structures or effect of the ground vibration. One of contact type sensors such as accelerometer is profitable for measurement of vibrational signals because of its wide measurement ranges. In the case of a gun barrel structure including high vibrational signals like shock waves, however, it is necessary to propose vibration measurement method filtering high frequencies. The purpose of the paper is to propose the proper vibrational measurement technique filtering high frequencies of a gun barrel type structure.

• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.129-131
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• 2000

The moving vehicle with disturbances has the 6 degree of freedom motion in the pitching, Yawing, and rolling directions of two independent axes. The control system in such a moving vehicle has to perform disturbance rejection. This paper present PID controller with disturbance rejection function, low sensitivity filter and notch filter for bending frequency rejection. The performance of a designed system has been certified by the simulation and experiment and experiment results.