• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.10
• /
• pp.1822-1828
• /
• 2008

This paper presents design parameter calculation methodology and its realization to construction for the 10/350${\mu}s$ lightning impulse current generator(ICG) modelled as double exponential function waveform with characteristic parameters ${\alpha},{\beta}$. Matlab internal function, "fzero" was applied to find ${\lambda}={\alpha}/{\beta}$ which is solution of nonlinear equation linearly related with two wave parameter $T_1$ and $T_2$. The calculation results for 10/350${\mu}s$ lightning impulse current show very good accuracy with error less 0.03%. Two type of 10/350${\mu}s$ ICGs based on the calculated design circuit parameters were fabricated by considering the load variation. One is applicable to the MOV based Surge protective device(SPD) for less 15 kA and the other is to test small resistive devices such as spark gap arrester and bonding device with maximum current capability 30 kA. The tested waveforms show error within 10% in comparison with the designed estimation and the waveform tolerance recommended in the IEC 61643-1 and IEC 60060-1.

• Journal of the Korean Data and Information Science Society
• /
• v.20 no.5
• /
• pp.857-867
• /
• 2009

The purpose of this paper is to suggest the methods of forecasting for the number of the elementary, middle and high-school student based on the proportion of promotion until 2026 year. The suggested methods are the proportion of promotion, mov baseverage, Holt-W bters model, SARIMA, regression fit. As the result, the abilities of forecasting by the method of moving average are better than those of other methods.

• Nuclear Engineering and Technology
• /
• v.38 no.2
• /
• pp.155-162
• /
• 2006

It is necessary to monitor periodically the operability of safety-related motor-operated valves (MOVs) in nuclear power plants. However, acquiring diagnostic signals for MOVs is very difficult, and doing so requires an excessive amount of time, effort, and expenditure. This paper introduces an accurate and economical method to evaluate the performance of MOVs remotely. The technique to be utilized includes electrical measurements and signal processing to estimate the motor torque and the stem thrust, which have been cited as the two most effective parameters in diagnosing MOVs by the US Nuclear Regulatory Commission. The motor torque is calculated by using electrical signals, which can be measured in the motor control center (MCC). Some advantages of using the motor torque signature over other signatures are examined. The stem thrust is calculated considering the characteristics of the MOV and the estimated motor torque. The basic principle of estimating stem thrust is explained. The developed method is implemented in diagnostic equipment, namely, the Motor Operated Valve Intelligent Diagnostic System (MOVIDS), which is used to obtain the accuracy of and to validate the applicability of the developed method in nuclear power plants. Finally, the accuracy of the developed method is presented and some examples applied to field data are discussed.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.4
• /
• pp.28-35
• /
• 2017

A main oxidizer shutoff valve controls the supply of the oxidizer flow into the combustion chamber of a liquid rocket engine. This shutoff valve also carries out the pre-chilling of oxidizer supply lines by permitting recycling flow for stable transient start of the engine. In the present paper, the flow tests for the recycling line of the valve were conducted in order to evaluate the cooling performance of the main oxidizer shutoff valve. In addition, cryogenic life-cycle tests were performed with an assumption of the increase of spring constant with increasing valve operating times due to ductile-brittle transition effects.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.12
• /
• pp.2255-2262
• /
• 2008

This paper presents a design parameter calculation methodology and its realization to construction for the damped oscillatory impulse current generator(ICG) modelled as damping factor $\alpha$. Matlab internal functions, "fzero" and "polyfit" are applied to find a which are solutions of second order nonlinear equation related with three wave parameters $T_{1},T_{2}$ and $I_{os}$. The calculation results for standard impulse current waveforms such as 4/10${\mu}s$, 8/20${\mu}s$ and 30/80${\mu}s$ show very good accuracy and this results make it possible to extend to generalization in the design of damped oscillatory lCG with any capacitor. 8/20${\mu}s$ ICG based on the calculated design circuit parameters is fabricated in consideration of the nonlinear load(MOV) variation. Comparisons of the tested waveforms with the designed estimation show error within 10% for the waveform tolerance recommended in IEC 60060-1 and IEEE std. C62.45.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.7 no.3
• /
• pp.93-106
• /
• 2001

Whether a ship is sub-standard or not shall be finally decided by the minimum standards laid down in international conventions or national standards having the same effects. The flag State is primarily responsible for implementing these standards as far as its own ships are concerned. And the port State shall, in the exercise of its rights under international law, take appropriate measures (including detention of ships identified as sub-standard), which are regarded as port State's supplementary role aiming at implementing these standards. The international standards are implemented by the regional co-operation in the form of the MOU(Memorandum of Understanding) on Port State Control in the Asia-Pacific Region on the ground that the PSC enforcement of only one country does not enable the eradication of sub-standard ships. Recently, EQUASIS which is an international database covering the whole world fleet change the regionalism of PSC into the globalization of PSC. However, there are many problems in Tokyo MOV and Korean PSC regime. In order to ensure the implementation of the standards laid down in international conventions and Tokyo MOU, the Korean and other country in Asia-Pacific shall settle the alienation from the actuality of the law, namely the problem of maritime administrative structure of non unifying PSC affairs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.2
• /
• pp.69-76
• /
• 2010

Recently, the natural environment changes drastically and the frequency of occurrence for lightning has gradually been increased. Such lightning delivers high volume of energy along the power line and communication line to the equipment in use. The high volume of energy arising from the lightning surge develops in fast velocity to destroy the facilities in power source and many other facilities in operation in sequential destruction with vast energy. This paper examines the characteristics of ZnO varistor to prevent from thermal runaway. We carry out performance evaluation of electrical characteristics on ZnO varistor. we will develop ZnO varistor Prevented from thermal explosion using test result of this paper.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.9 no.1
• /
• pp.15-19
• /
• 2013

The auxiliary feedwater is an important to remove the heat from the reactor core when the main feedwater system is unavailable. In most initiating events in Probabilistic Safety Assessment(PSA), the operaton of this system is required to mitigate the accidents. For one of domestic nuclear power plants, a design change of a turbine-driven auxiliary feedwater pump(TD-AFWP), pipe, and valves in the auxiliary system is implemented due to the aging related deterioration by long time operation. This change includes the replacement of the TD-AFWP, the relocation of some valves for improving the system availability, a new cross-tie line, and the installation of manual valves for maintenance. The design modification affects the PSA because the system is critical to mitigate the accidents. In this paper, the safety effect of the change of the auxiliary feedwater system is assessed with regard to the PSA view point. The results demonstrate that this change can supply the auxiliary feedwater from the TD-AFWP in the accident with the motor-driven auxiliary feedwater pump(MD-AFWP) unavailable due to test or maintenance. In addition, the change of MOV's normal position from "close" to "open" can deliver the water to steam generator in the loss of offsite power(LOOP) event. Therefore, it is confirmed that the design change of the auxiliary feedwater system reduces the total core damage frequency(CDF).

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.10
• /
• pp.11-23
• /
• 2012

To achieve efficient code size reduction, this paper proposes a new compressed instruction set architecture for the OpenRISC architecture. The new instructions and their corresponding formats are designed by the profiling information of the existing instruction usage. New 16-bit instructions and 32-bit instructions are proposed to compressed the existing 32-bit instructions and instruction sequences, respectively. The proposed instructions can be classified into three types. The first is the new 16-bit instructions for the frequent normal 32-bit instructions such as add, load, store, branch, and jump instructions. The second type is the new 32-bit instructions for the consecutive two load instructions, two store instructions, and 32-bit data mov instructions. Finally, two new 32-bit instructions are proposed to compress function prolog and epilog code, respectively. OpenRISC hardware decoder is extended to support the new instructions. Experiments show that the efficiency of code size reduction improves by an average of 30.4% when compared to the OR1200 instruction set architecture without loss of execution performance.

• The Plant Pathology Journal
• /
• v.22 no.2
• /
• pp.155-160
• /
• 2006

A strain of Pepper mottle virus (PepMov) was isolated from chili pepper plants in Korea. In host range study, this virus, designated PepMoV-SNU1, shared most characteristics with PepMoV isolates reported previously. Thermal inactivation point ($45^{\circ}C\;to\;75^{\circ}C$) and dilution end point ($10^{-1}\;to\;10^{-4}$) of PepMoV-SNU1 showed differences depending on the propagation hosts. Cylindrical and pinwheel-shaped inclusions were always observed in pepper leaf tissues infected with the virus alone. Unexpectedly, a special structure of pinwheel shaped inclusion surrounded with unknown small spots was also observed in the leaf section when co-infected with a strain of pepper mild mottle virus. The partial sequence of coat protein gene and 3' untranslated region of PepMoV-SNU1 showed 98% identity with those of other PepMoV isolates. A primer pair derived from 3' end of the coat protein gene and poly A tail regions were designed. Optimal detection condition of PepMoV-SNU1 by RT-PCR was tested to determine appropriate annealing temperature and additional volumes of oligo-dT (18-mer), dNTP, and Taq polymerase. Under the optimized condition, an expected 500 Up PCR-product was detected in pepper leaves infected with PepMoV-SNU1 but not in healthy plants.