• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.97.6-97
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• 2002

In this paper, we present an arrayed flexible tactile sensor, which can detect contact normal forces as well as positions. The tactile sensor is developed using Polyvinylidene Fluoride (PVDF) that is known as piezoelectric polymer, and the surface electrode is fabricated using silk-screening technique with silver. We develop a charge amplifier in order to amplify the small signal from the sensor, and a fast signal processing unit by using a DSP chip. The developed tactile sensor is physically flexible and it can be deformed three-dimensionally to any shape so that it can be placed on anywhere on the curved surface. In the future, the developed sensor is applied to a dexterous robotic hand...$\textbullet$ Tactile sensing, PVDF, Robot hand

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1258-1259
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• 2008

In this paper, the variable tendency of the piezoelectric constant and resonance characteristics of the piezoelectric ceramics due to the electric field is studied. The practical application of piezoelectric ceramics is not only applied in field of small signal. For example, in case of an ultrasonic motor, 120 ${\sim}$ 130Vrms of driving voltage is needed. Therefore, to examine the characteristics of piezoelectric ceramics in large signal contributes to reducing the susceptibility to the multifarious application and securing the ease of the production of control circuit. These contributions may be connected to the expansion of industrial application. We fabricated disk-type piezoelectric ceramic samples by using conventional method and measured the resonance characteristics of these samples under from low to high voltage driving conditions. According to increasing the value of the input voltage, we measured the resonance frequency of the piezoelectric ceramic, and inquired into the cause of these phenomena.

• Journal of the Korean Statistical Society
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• v.26 no.2
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• pp.181-198
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• 1997

The variable sampling rates scheme is proposed by taking random sample size and sampling interval during the process. The performance of the scheme is measured in terms of the average time to signal adjusted by teh sampling cost when the process is out of control. This measurement evaluates the effectiveness of the scheme in terms of the cost incurred due to nonconformation as well as sampling. The variable sampling rates scheme is shown to be effective especially for small and moderate shifts of the mean when compared to the standard scheme.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.919-929
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• 2013

We compared two basic methods, combine-accumulate method and accumulate-combine method, using the past quality information in multivariate quality control procedure for monitoring mean vector of multivariate normal process. When small or moderate shifts have occurred, accumulate-combine method yields smaller average run length (ARL) and average time to signal (ATS) than combine-accumulate method. On the other hand, we have found from our numerical results that combine-accumulate method has better performances in terms of switching behavior than accumulate-combine method. In industry, a quality engineer could select one of the two method under the comprehensive consideration about the required time to signal, switching behavior, and other physical factors in the production process.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.804-807
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• 1996

This paper addresses the small-signal stability and control problems associated with a Static Var Compensator and its power system stabilizer. The major emphasis is on determination of suitable location for SVC arid stabilizer signal tuning through eigenvalues and frequency response techniques. To determinate of suitable location for SVC, this paper used transfer function residues. Adequate oscillation damping is achieved by the use of stabilizing signals, designed through frequency response techniques and added to SVC. The study system is Benchmark System.

• Journal of IKEEE
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• v.22 no.3
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• pp.858-861
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• 2018

In this paper, we propose the development of a small $360^{\circ}$ oral scanner lens module. The proposed small $360^{\circ}$ oral scanner lens module consists of a small $360^{\circ}$ high resolution(4MegaPixel) lens optical system, a 15mm image sensor unit, and a small $360^{\circ}$ mouth scanner lens external shape. A small $360^{\circ}$ high resolution lens optical system produces a total of nine lenses, the outer diameter of the lens not less than 15mm for use by children through the ages of adulthood. Light drawn by a small $360^{\circ}$ high resolution lens optical system is $90^{\circ}$ flexion so that image images are delivered to image sensors. The 15mm image sensor unit sends the converted value to the ISP(Image Signal Processor) of the embedded board after an image array through the column and the row address of the image sensor. The small $360^{\circ}$ mouth scanner lens outer shape was designed to fix the race to the developed lens. Results from authorized testing agencies to assess the performance of proposed small $360^{\circ}$ oral scanner lens modules, The optical resolving power of $360^{\circ}$ lens was more than 30% at 150 cycles/mm, $360^{\circ}$ lens angle was $360^{\circ}$ in vertical direction, $42^{\circ}{\sim}85^{\circ}$ in vertical direction, and lens distortion rate was 5% or less. It produced the same result as the world's highest level.

• Journal of Biosystems Engineering
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• v.36 no.6
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• pp.467-475
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• 2011

Aerial spraying technology using a small unmanned helicopter is an efficient and practical tool to achieve stable agricultural production to improve the working condition. An attitude controller for the agricultural helicopter would be helpful to aerial application operator. In order to construct the flight controller, a state space model of the helicopter should be identified using a dynamic analysis program, such as CIFER$^{(R)}$. To obtain the state space a model of the helicopter, frequency-sweep flight tests were performed and time history data were acquired using a custom-built stick position transmitter. Four elements of stick commands were accessed for the collective pitch (heave), aileron (roll), elevator (pitch), rudder (yaw) maneuvers. The test results showed that rudder stick position signal was highly linear with rudder input channel signal of the receiver; however, collective pitch stick position signal was exponentially manipulated for the convenience of control stick handling. The acquired stick position and flight dynamic data during sweep tests would be analyzed in the followed study.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1123-1125
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• 2002

In this paper, interleaved boost converter is applied as a pre-regulator in switch mode power supply. Interleaved Boost Power Factor Preregulator (IBPFP) can reduce input current ripple as a simple voltage control loop only without inner current loop, because input current is divided each 50% by two switching devices. IBPFP can be classified as three cases from duty ratio condition in continuous current mode and be carried out state space averaging small signal modeling. According to modeling, the PID controller is applied and voltage control loop is constructed for suitable design condition. From frequency domain analysis, it is verified that control system is satisfied with design condition of switch mode power supply.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1001-1006
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• 2003

This paper presents the pedestrian navigation algorithm and the error compensation filter. The pedestrian navigation system (PNS) consists of the MEMS inertial sensors, the fluxgate, and the small-size GPS receiver. PNS calculates the navigational information using the signal patterns of the accelerometers. And the navigational information is completed by integration of the patterns, the fluxgate, and the GPS information. In general, PNS can provide the better solution than the low-cost inertial navigation system.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2023-2027
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• 1997

This paper presents the dynamic analysis and control-loop design of a zero-voltage-switched full bridge (ZVS-FB) PWM dc/dc converter. Based on the small-signal analysis results, the control-loop is designed using a simple two-pole one-zero compensation circuit. Design results are verified by both computer simulations and experimental data obtained from a 2kW prototype converter.