• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.85-95
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• 2009

In the binaural synthesis environments, wide varieties of the head-related transfer functions (HRTFs) that have measured with a various direction would be desirable to obtain the accurate and various spatial sound images. To reduce the size' of HRTFs, interpolation has been often employed, where the HRTF for any direction is obtained by a limited number of the representative HRTFs. In this paper, we study on the distortion measures for interpolation, which has an important role in interpolation. With lhe various objective distortion metrics, the differences between the interpolated and the measured HRTFs were computed. These were then compared and analyzed with the results from the listening tests. From the results, the objective distortion measures were selected, that reflected the perceptual differences in spatial sound image. This measure was employed in a practical interpolation technique. We applied the proposed method to four kinds of an HRTF set, measured from three human heads and one mannequin. As a result, the Mel-frequency cepstral distortion was shown to be a good predictor for the differences in spatial sound location, when three HRTF measured from human, and the time-domain signal to distortion ratio revealed good prediction results for the entire four HRTF sets.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11b
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• pp.15-17
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• 2004

The quality of X -ray image is depending on the acquired signal pattern So far, the MTF(modulation transfer function) of medical image system has been obtained through various kinds of calculationprocesses after using SWRF (A square wave response function method) to print out it into films. In this study, a tool has been developed that can help the actual user who actually creates the medical images measure the MTF of the finaldisplay image very simply by applying Borland C++ builder software as well as LEAD tools software for the SWRF calculation process to analyze the MTF even on the display image. Films have been printed out by this newly developed MTF measuring tool under the same conditions with the ones for the existing tools and also the calculation method has shown no difference with any existing SWRF calculation method. By using this, it was found out that the MTF of the resolving power of the computed radiography(CR) Image plate (IP) that is a conventional X-ray detection system Jar the conventional X-ray purpose was about 10% at the range of 3.00 LP/mm.

• ETRI Journal
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• v.36 no.6
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• pp.905-912
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• 2014

In this paper, a new architecture is proposed to achieve complexity efficiency in implementing variable pulse position modulation (VPPM). VPPM, specified in IEEE 802.15.7, can support wireless communication and dimming control simultaneously using visible light. The proposed architecture is based on the VPPM signal property in which the transition point of the modulated output is obtained by counting the sample index and comparing it to both the assigned dimming factor and the transmitting data. Therefore, the proposed architecture can be composed of simple logics, including a counter, a comparator, and an inverter, all of which are insensitive to the dimming resolution in contrast to a conventional codeword-table method. This paper describes the verification of the proposed algorithm through a register-transfer level implementation of the codeword and proposed architectures. In comparison with the codeword-table method, the proposed method gains a nine-fold complexity reduction at a 1% dimming-step resolution.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.124-133
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• 2007

Active vibration isolation systems need the following performance specifications which are different from those of existing positioning systems: usage of seismic sensors, strict suppression of phase lead/lag in signal processing for sensors and actuators, excellent control in low frequency range and so on. In consideration of such specifications, a 3-DOF precision stage for vibration isolation is designed and modeled based on the physical characteristics. Then the major parameters such as spring constants and damping coefficients are valued by the system identification method using empirical transfer function. Finite element analysis is used as a verification and simulation tool throughout this research. This paper lays the foundation for the future research on the control of the active vibration isolation system.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.157-160
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• 1996

Physical systems axe generally continuous-time in nature. However as the data measured from these systems is generally in the form of discrete samples, and most modern signal processing is performed in the discrete-time domain, discrete-time models are employed. This paper describes methods for estimating the coefficients of continuous-time system within a closed loop control system. The method employs a recursive estimation algorithm to identify the coefficients of a discrete-time bilinear-operator model. The coefficients of the discrete-time bilinear-operator model closely approximate those of the corresponding continuous-time Laplace transform transfer function.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.294-298
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• 2001

Satellite propulsion system is employed for orbit transfer, orbit correction, and attitude control. The monopropellant feeding system in the low-earth-orbit satellite blowdowns fuel to the thrust chamber. The thrust produced by the thruster depends on fuel amount flowed into the combustion chamber. If the thruster valve be given on-off signal from on-board commander in the satellite, valve will be opened or closed. When the thrusters fire fuel flows through opened thruster valve. Instantaneous stoppage of flow in according to valve actuation produces transient pressure due to pressure wave. This paper describes transient pressure predictions of the KOMPSAT2 propulsion system resulting from latching valve and thrust control valve operations. The time-dependent set of the fluid mass and momentum equations are calculated by Method of Characteristics (MOC).

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.3 no.1
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• pp.11-19
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• 1992

To design of Ultra-wideband amplifier, we analyzed the inductor peaking to reduce the capacitance effect of GaAs MESFET in upper frequency edge. And we deduced an optimun inductor peaking element from transfer function of GaAs MESFET small-signal equivalent circut and realized the Feedback Amplifier Module (FAM) having flat gain. We design the imput and output impe dance matching networks by Real-Frequency Method. It show that the gain of designed amplifier has a 6.38dB with gain variation 0.56 at 0.1~12 GHz frequency gand by computer simu-lation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.54-58
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• 1997

In this study, study, about Automatic Loader and Unloader system which can directly be used for material handing and tool operating is moving linear transfer system for mainly forming of small electronic unit and other at press line. This system for been installed in a press in order to load and unload a workpiece from a press die. Control method be used Programmable logic control(PLC) unit. other Control equipment of system is Motor drive, Positioning Control and so on. It took data of input from each sensor and send signal of output to actuator by sequence program. We try to Characteristics test of this system has good condition when operating by laser measurement

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.107-112
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• 1997

In this study of made Autmation system is moving linear transfer system for mainly forming of small electronic unit and other at press line. This system for loading and unloading a workpiece has been installed in a press in order to load and unload a workpiece from a press die. Main Control method be used PLC. It took data of input from each sensor and send signal of output to actuator by sequence program also, we try to Characteristics test of this system has good condition when operating with raser measurmant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.264-268
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• 2009

In this paper, the two PCB design method results of boost converters are simulated with same circuit device parameters. One is modeled with microstrip structure and the other is modeled two layers structure without reference plane. Between devices of each circuit are routed 5 centimeters. When the switching frequency is operated 100kHz, the overshoot by signal reflection and the noise characteristics by frequency spectrum for the output voltage and current of the power switch is compared and analyzed using simulation.