• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.318-329
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• 1994

This paper deals with the finite wordlength effect on the performance of digital PID controllers. The finite wordlength, one of the major limitation factors in digital controllers, results on two kinds of quantization error : the signal quantization error and the coefficient quantization error. This paper derives the variance of the plant output due to the signal quantization error. Using stability margins as performance criterion, the statistical wordlength concept is adopted for coefficient wordlength selection. Finally, the experimental results exhibit satisfactory performance of the digital PID controller with statistical coefficient wordlength.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.161-164
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• 2003

This research presents the parallel control scheme of PID servo-driver for shaping of the curved glass. The designed system consists of a PC, main controller and 11 servo-drivers. Each elements are connected by using RS-232C and 8-bit bus communication. In order to guarantee the stability and the control performance, we use the LM629, a precision PID motion controller, and LMD18200, a H-bridge on the servo-drivers. PC calculates position values of 11 DC motors by using the pre-determined curvature value and offers the user interface environment operator.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.201-203
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• 1998

This paper presents the framework for analysis of small-signal stabili1ty. In this framework the equilibrium points of system DAE model are traced using continuation method and instability points are determined on the solution path. Especially Implicit shift QR-modified ARnoldi method is utilized to calculated the rightmost eigenvalues. ISPS measure is utilized to determine critical parameters.

• Proceedings of the Korean Society of Potoscience Conference
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• 2005.06a
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• pp.21-23
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• 2005

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.84-88
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• 2013

In this paper, the low price signal generator with capability of frequency high-resolution and variable sync pulse has implemented. It fulfils well the requirements for SS-OCT of the frequency resolution less than 1Hz, frequency stability of ${\leq}{\pm}0.5Hz$/10 min and variable sync pulse output timing. Through its performance test applied to wavelength swept laser, 120 nm sweeping range and 10 mW average optical power were obtained. This shows that the realized sine-wave generator can replace the commercial high cost and high performance signal generators employed by current SS-OCT systems.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.1
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• pp.94-100
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• 2007

MVRS's measuring principles are based on the Doppler principle. It measures the velocities near the muzzle using the doppler signal output from the antenna and then predicts the velocity of the bullet leaving the muzzle by performing the regression analysis on previous measured velocities. There are a number of error sources when calculating the muzzle velocity. Antenna has long term frequency stability error and the doppler signal from the antenna has noise. These two error sources influence the accuracy of estimated velocities from the doppler signal. Estimated velocity errors result in the random error of data statistics. And when performing a regression analysis these random error components are transferred to the fitting error component. This study also analyzed the error components according to the hardware limitations of MVRS-700 and the signal processing method, and presented the calculated uncertainty of muzzle velocity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.43-47
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• 2001

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose on the ESR signal intensity and to identify the stability of radicals after 9 weeks of storage in order to detect irradiated shellfishes. The irradiated shellfishes (short-necked clam, purplish washington clam, freshwater clam, jackknifed clam, scallop and hard-shell mussel) presented an asymmetric absorption in shape at $g_{1}$=2.002~2.003 and $g_{2}$=1.998. The strength of the ESR signal increased linearly with the applied doses (1~7 kGy). A highly positive correlation coefficients ($R^{2}$=0.9136~0.9896) were obtained between the irradiation dose and corresponding ESR signal intensity. The intensity of the signals after irradiation was stable even after 9 weeks of storage at 5$\pm$1$^{\circ}C$.

• Journal of Welding and Joining
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• v.18 no.4
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• pp.82-86
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• 2000

Gas metal arc welding(GMAW) is regarded as one of the best candidate for welding automation in industrial joining application. It is important to monitor the weld quality for the high performance weld automation. In GMAW, weld quality is closely related to arc stability especially. In this paper, arc light signal is measured and spectrum analyzed to the detect the variation of the weld quality. The FFT of the signal showed that the amplitude variance of FFT power spectrum was very large in poor weld process such as the decrease of weld bead width and height. The results show that it is possible to detect the weld defect position in weld process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1671-1675
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• 2012

In this paper, we fabricate multi-channel receiver for radar system. This receiver at X-band can be received 8 signal of an identical characteristic, dynamic range has more than 80[dB]. To process direct received signals, this system has the built-in two digital de-modulators which offer the minimum loss on the receiving signal path and has high stability by adding Built-In Test. The gain, noise figure, difference of amplitude and phase on the signal path is respectively $14{\pm}2$[dB], 19[dB], ${\pm}2$[dB], $10^{\circ}$ and below.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.2
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• pp.239-242
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• 2001

Electron spin resonance(ESR) spectroscopy was used to investigate the effect of irradiation dose on the ESR signal intensity of irradiated spices and to identify the stability of radicals after storage. Red, white and black peppers, and garlic powders were irradiated with doses of 0, 1, 5, 10, 20 and 30 kGy at room temperature using a Co-60 irradiator. Triplet ESR signals were observed in irradiated pepper powders, while singlet ESR signals were observed in irradiated garlic powders. Those characteristic signals were not detected in non-irradiated samples. The strength of ESR signals linearly increased with the applied doses(1~3 kGy). Highly positive correlation coefficients ($R^2$=0.9757~0.9933) were obtained between the irradiation doses and the corresponding ESR signal intensities. The signal intensities of irradiated samples were stable even after 97 days of storage at room temperature.