• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.4
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• pp.12-20
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• 1981

In this paper, Band-limlted Gaussian Random Noise and PRBS(pseudo random hinary sequence) are used as a test signals to estimate the dynamic characteristics of the ocuiomotor system. Eye movements of the human subject are measured by E.O.G(electro-oculography) and the control characteristics of the oculomotor system are studied by random signal an-alysis based on the statistical communication theory. The conclusions are summerized as follows. (1) From the frequency response, the gain curve rises slightly at the regions of 0.7~0.9 Hz and 1.8~2 Hz due to the saccades which are occurred during usual tracking. (2) The average rate of information transfer by the oculomotor control system is 1.24 bits/sec, being calculated from the power spectral density and the cross spectral density for the Gaussian random input.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.12
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• pp.541-554
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• 1986

This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.4
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• pp.201-208
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• 2002

In this paper, we present a new formulation using time-domain electric field integral equation (TD-EFIE) to obtain transient scattering response from arbitrarily shaped three-dimensional conducting bodies. The time derivative of the magnetic vector potential is approximated with a central finite difference and the scalar potential is time averaged by dividing it into two terms. This approach with an implicit method using central difference results in accurate and more stable transient scattering responses from conducting objects. Detailed mathematical steps are included and several numerical results are presented and compared with the inverse discrete Fourier transform (IDFT) of the frequency-domain solution.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.603-605
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• 1996

The SLIM used in the conveyance system has been generally developed the controller based on the slip frequency control and the VVVF method to obtain the quick response for the position control signal. This paper deals with the trust control of the SLIM by vector control with Bang-Bang condition. Also, the control system is composed of the PI controller for soft start of the SLIM and the q-axis current controller for correction in phase with Space Vector for reducing the harmonic pulsation in low speed. The processing for vector control and robust dynamic breaking control is carried out by MC80196KC micro processor and IGBT module. The proposed scheme is verified through the computer simulation and experiments for the 10KW SLIM.

• Culinary science and hospitality research
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• v.6 no.2
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• pp.271-290
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• 2000

The objectives of this study were to develop program in education & training of dietitians and cooks in contracted foodservice management company, The instruments were developed by reviewing extensive literatures on education programs and by interviewing with dietitians and cooks who were working in contracted foodservice management company. A total of 400 questionnaires was hand delivered at 14 contracted foodservice management companies by designated coordinators. A total of 286 questionnaires was usable; resulting in a 70.0%, response rate. Statistics data analysis was completed using the SPSS program for frequency analysis, reliability, mean value, t-test, ANOVA and Crohnbach's alpha coefficient. Crohnbach's alpha coefficients for dietitian's scale and cook's scale were 0.9548 and 0.9513. A few things were suggested according to the results of the survey: 1. The dietitians and the cooks wanted to take a continuing education to improve their job. Therefore the contracted foodservice management company should provide them with the systematic education according to their job experience. 2, As the continuing education for dietitians and the continuing education for cooks were disappeared, Korean Dietitian Association and Korean Culinary Association should make a certified continuing education program and give them a new knowledge and a changeable food culture.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.366-370
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• 2006

An optical microphone incorporating a reflective diaphragm and a fiber-optic head was demonstrated. The diaphragm was made of a micromirror membrane which is suspended by a silicon bar connected to a frame, allowing fer a displacement induced by acoustic waves. A compact, simple optical head was implemented by exploiting a single multimode fiber. For the assembled microphone, the static characteristics were investigated to find the operation point defined as the optimum distance between the head and the diaphragm, and a flat frequency response with a variation of $\sim$2dB for the range of up to 2 kHz was accomplished.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.38-46
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• 2000

This study have established proper mathematical equivalent model of Brushless DC (BLDC) motor and estimated the motor parameter by means of the back-emf measurement as being the step input to the controlled target BLDC motor. And the validity of proposed estimation method is confirmed by the test result of step response. As well, we have designed the reasonable digital controller as a consequence of the root locus method which is obtained from the open-loop transfer function of BLDC motor with hall sensor, and the determination of control gain for variable speed control. Here, revised Ziegler-Nichols tuning method is applied for the proper digital gain establishment, and the system stability is verified by the frequency domain analysis with Bode-plot and experimentation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.3 s.8
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• pp.73-78
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• 2005

In this paper, a bandpass filter with excellent cut off characteristic due to transmission zero using bypass coupling capacitor and with superior harmonic characteristic by interdigital capacitor is suggested. The measurement results for SIR bandpass filter with bypass coupling capacitor and interdigital capacitor show that the insertion loss is less than 1.9 dB and the return loss is better than 15.4 dB with 4.2 % bandwidth at the center frequency of 5.78 GHz.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.3
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• pp.312-322
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• 1999

A ultrasonic transduce with a single acoustic matching layer has been designed as an attempt to increase the bandwidth of underwater transducer. The wideband resonance condition was accomplished by attaching a single matching layer on the front face of a ceramic resonator composed of a piezoelectric bar, a taper part and a head part. A modified Mason's model was used for the performance analysis and the design of transducers, and the constructed transducers were tested experimentally and numerically by changing the impedance and thickness of the matching layer in the water tank.The obtained results are summarized as follows:1. Measured resonant and antiresonant frequencies of the piezoelectric transducer with no matching layer in air were 24.7 kHz and 25.6 kHz, respectively. 2. Two resonant frequencies of the piezoelectric transducer with a single matching layer were 21.7 kHx and 26.9 kHz, respectively, in air and 21.4 kHz and 22.7 kHz, respectively, with a water load.3. Two distinct resonance peaks in the transmitting voltage response(TVR) of the developed transducer were observed at 22.0 kHz and 25.8 kHz, respectively, with center frequency of 24.0 kHz. The values of TVR at these frequencies were 130.1 dB re $1 \muPa$/V at 22.0 kHz and 128.5 dB re $1 \muPa$/V at 25.8 kHz, respectively.Reasonable agreement between the experimental results and the numerical values was achieved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.748-756
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• 2007

In SIR filter, fringing capacitances and discontinuities yield a distorted frequency response from those expected by design formulas, especially in higher frequencies. In this paper, a procedure is presented in order to compensate for fringing capacitances and step impedance discontinuities by EM simulation for a 5th order SIR filter. This method propose the procedure of tuning the coupling and the length of individual resonator by EM simulation. For the filter composed by the tuned resonators, no further tuning is required. The procedure is experimentally justified by comparing the measured data of the fabricated filter with the simulation results.