• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.84-92
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• 1998

A program was developed to analyze the electrical characteristics and harmonic distrotion in a two-dimensional silicon BJT. The finite difference equations of the small signal and its second and thired harmonics for basic semiconductor equations are formulated treating the nonlinearity and time dependence with Volterra series and Taylor series. The soluations for three sets of simultaneous equations were obtained sequantially by a decoupled iteration method and each set was solved by a modified Stone's algorithm. Distortion magins and ac parameters such as input impedance and current gains are calculated with frequency and load resistance as parameters. The distortion margin vs. load resistancecurves show cancellation minima when the pahse of output voltage shifts. It is shown that the distortionof small signal characteristics can be reduced by reducing the base width, increasing the emitter stripe length and reducing the collector epitaxial layer doping concentration in the silicon BJT structure. The simulation program called TRADAP can be used for the design and optimization of transistors and circuits as well as for the calculation of small signal and distortion solutions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1104-1112
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• 1988

In this study the structure of a two phase detonation has been numerically investigated through the assumption of a steady and one-dimensional flow in the suspension of carbon particles and pure oxygen. The bow shock formation in front of carbon particles has been taken into consideration when the relative velocity of gas flow with respect to the particle exceeds the local speed of sound. But its effect was found to be very limited to the induction zone only. Furthermore the interior particle temperature distribution has been considered in this work. It was found that the inner temperature gradient was very steep in the region of high relative velocity. On the while the temperature distribution inside the particle was almost uniform in the region of low relative velocity. Overall, the effect of the interior particle temperature distribution has been significant in the two phase detonation.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.3
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• pp.93-101
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• 1998

In Integrated Tube Components(ITC) process in themanufacturing of color display tube, we describe the necessity of the convergence measurement method using photo sensors. Compared with methods using 1D or 2D cameras, its characteristics is to use of moving image patterns and fixed sensors. This measurement method is formulated as the measurement problem of the phase difference in phase changing periodic signals. The convergence measurement system using photo sensors, for the good performance, must have a small standard deviation for the repetitive measurement in the same condition and a fast measurement time for thecovergence change. By above two conditions, we proposed the real time measurement algorithm of the pahse difference using fundametal and harmonic in phase changing periodic signals. And, the proposed algorithm is applied to the convergence measurement system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1059-1065
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• 1998

It is very crucial to make the phase holograms have the exact phase difference in the fabrication process. We have developed a fabrication criterion of obtaining the exact phase difference of the holograms by using the relation between the zeroth order intensity of diffected beam and the relative phsse difference of the fabricaated holograms. We have fabricated holograms having phaes of .pi. and .pi./2, respectively, and we could get multi-phase holograms by combining these two binary thase holograms.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.70-77
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• 2005

The study was results obtained from the trial make of the hybrid GPS-electromagnetic(EM) compass which overcome shortcoming of GPS compass and EM compass. The results were summarized as follows: GPS compass detected the stable ship's heading at 0.1^{\circ}$ intervals with the turning angular velocity of less than 25^{\circ}$/sec in the experiment for the characteristics of turning angular velocity with stepmotor, but in case of over 25^{\circ}$/sec the compass did not detect it. On the contrary, the EM compass always indicated the ship's heading with no connection of the turning angular velocity, however the compass is low accuracy compared with GPS one owing to a compass error. The ship's headings by the hybrid GPS-EM compass were displayed at fixed point and moving by car; if the GPS compass work the headings were displayed by GPS compass, if not, the heading is provided stably by adding or subtracting of a compass error to the heading of EM compass. Also, each ship's heading was derived from not only the GPS compass but also the EM one by add or subtract of the compass errors, and then was worked covariance for the analogy. The results show that the ship's heading of two compasses has been verified the similarity to 95% confidence level.