• Nuclear Engineering and Technology
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• v.20 no.1
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• pp.47-53
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• 1988

The objective of this study is to evaluate the reliability of the High Head Safety Injection System (HHIS) of KNU 5, 6, 7 and 8 following the removal of safety injection signal (s-signal) from the mini-flow bypass line valves of charging/safety injection pumps. The unavailability of HHSIS and the rupture probability of a charging/safety injection pump have been computed for two different cases; with s-signal on and removed. The results show that when the s-signal is removed from the mini-flow bypass line valves, the unavailability of HHSIS slightly increases while the rupture probability of a charging/safety injection pump is significantly reduced. Hence, based upon the results of this study we conclude that it is more reasonable to remove the s-signal from the mini-flow bypass line valves of KNU 5, 6, 7 and 8 in the normal plant operation. And to improve the availability of HHSIS, the modification of operational procedures and the emphasis on operator training are recommended.

• Journal of Chest Surgery
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• v.36 no.11
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• pp.834-838
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• 2003

Background: Deairing from the heart after open heart surgery(cardiopulmonary bypass) is a very important procedure. Artificial arteriovenous fistula was used to remove air, and the efficiency was evaluated by transesophageal echocardiography. Material and Method: Just before termination of cardiopulmonary bypass, a standard pressure transducer line is connected between the stopcocks of the connections in the arterial and venous circuits, creating a small controlled arteriovenous fistula between the arterial and venous cannulas. The degree of intracardiac air and air removal time were evaluated either by transesophageal echocardiography or direct vision of pressure transducer line. Result: By simple procedure, cardiopulmonary time was shortened and air clearing can be confirmed using echocardiography in a few minutes. Conclusion: Creation of arteriovenous fistula using small connecting line between aortic and venous cannula is a very simple and effective method of deairing and preventing of air embolism after open heart surgery.

• Proceedings of the Korean Nuclear Society Conference
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• 2003.05a
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• pp.170.1-170.1
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• 2003

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.149.2-149.2
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• 2004

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1597-1602
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• 2003

Numerical analysis is carried out to assess the temperature distribution on the mixing tee line of Residual Heat Removal System (RHRS). In RHRS, hot and cold fluids of main and bypass piping are mixed and unmixed by the flow rate or piping layout. Thermal stratification phenomenon is a cause of major degradation on RHRS piping. According to the analysis for each operation modes, maximum temperature difference between top and bottom of piping were evaluated about 60K when the flow rate of main and bypass lines is same. Temperature difference will be decreased at the elbow on RHRS piping if the length of vertical piping is increased.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.8
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• pp.610-616
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• 1989

The line commutated inverter with GTO forced commutation is described in this paper. The presented circuit has one bypass GTO inserted in DC power side line commutated thyristor inverter. The extended commutation region with additional one GTO-commutation is clearly shown. Also, a new PWM pattern is presented to decrease the effects of harmonics for commutation. A criterion for designing the AC filter parameters to decrease harmonics of AC part is given. The simulation and experimental results clearly show that the proposed circuit can be adapted in the application of regeneration.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.130-132
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• 1988

A usual line-commutated thyristor inverter with additional onebypass GTO is presented. With the added one bypass GTO, the extended commutating area is investigation and restrictions for the PWM to reduce the high frequency component of line current are shown.

• 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.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.253-258
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• 2001

This paper introduces a simple nonlinear adaptive control method for pipeline inspection gauge (PIG) flow in natural gas pipeline. The dynamic behavior of the PIG depends on the different pressure across its body and the bypass flow through it. The system dynamics includes: dynamics of driving gas flow behind the PIG, dynamics of expelled gas in front of the PIG, and dynamics of the PIG. The method of characteristics (MOC) and Runger-Kuta method are used to solve the dynamics of flow. The PIG velocity is controlled through the amount of bypass flow across its body. A simple nonlinear adaptive controller based on the backstepping method is introduced. To derive the controller, three system parameters should be measured: the PIG position, its velocity and the velocity of bypass flow across the PIG body. The simulation has been done with a pipeline segment in the KOGAS low pressure system, Ueijungboo-Sangye line to verify the effectiveness of the proposed controller. Three cases of interest are considered: the PIG starts to move at its launcher, the PIG arrives at its receiver and the PIG restarts after stopping in the pipeline by obstruction. The simulation results show that the proposed nonlinear adaptive controller attained good performance and can be used for controlling the PIG velocity.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.245-249
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• 2007

The tendency of lightning surge to propagate displays the difference for applicable power and equipment. However, looking into the subject equipment with the lightning surge, the lightning surge can be divided in between the two lines of power, between the power line and the ground, the power line and the PE conductor, between the neutral line and the ground and the like. In addition, in the event of the communication equipment, there exists the case of lightning surge entered from the power line in addition to the entry between the communication lines, the communication line and the ground. In this study, the tendency of propagation of lightning surge penetrated on to the subject equipment is analyzed through the empirical experiment in accordance with the ground method by using the independent ground, common ground, bypass arrester and others among the techniques for safety improvement in power lines.