• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.348-350
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• 2003

In recent years, with the continuous development of modem power system, the need for high performance protection to meet the customers' requests for more stable and reliable power supply has become increasingly emphasized. So, there is urgent need for a proper testing platform about not only existing digital protection relay but also new digital protection relay on the transmission line. It is also dynamic-state test which can test the performance of digital relay. This paper suggests basic system model for testing transmission line protection using PSCAD/EMTDC, and presents the process of the component modeling in the basic system.

• 연구논문집
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• s.31
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• pp.89-99
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• 2001

This paper presents the modeling and analysis of dynamic characteristics of hydraulic snubber in electric power plant. The nonlinear state-space model of 14th order to describe the dynamics of the snubber was established by Simulink. The simulation results show that the hydraulic snubber reacts as like the conventional shock absolvers against the high pulse shock load. The snubber also shows the peculiar characteristics to the small step load, which temporarily lock the control valves up, however maintain same steady-state pressures of all internal chambers in the long run. Two case studies for the analysis of the snubber are addressed. Practical pulse testing method was also proposed to identify the frequency response of the snubber.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.640-648
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• 2014

Excessive power dissipation is one of the major issues in the testing of VLSI systems. Many techniques are proposed for scan test, but there are not so many for logic BIST because of its unmanageable randomness. This paper presents a novel low switching activity BIST scheme that reduces toggle frequency in the majority of scan chain inputs while allowing a small portion of scan chains to receive pseudorandom test data. Reducing toggle frequency in the scan chain inputs can reduce test power but may result in fault coverage loss. Allowing a small portion of scan chains to receive pseudorandom test data can make better uniform distribution of 0 and 1 and improve test effectiveness significantly. When compared with existing methods, experimental results on larger benchmark circuits of ISCAS'89 show that the proposed strategy can not only reduce significantly switching activity in circuits under test but also achieve high fault coverage.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.7-14
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• 2014

Inverter module, which feeds the converted power to the traction motor for EMU. Consists of the power semiconductors with their gate drive unit(GDU)s and the control computer for driving, voltage, current and speed controls. Electrolytic condenser, connected to the gate drive unit and a core component to drive the power semiconductor, has problems such as reduction in lifetime and malfunction caused by electrical and mechanical characteristic changes from heat generation during high speed switching for generation of stable power. In this study, To check the service life of electrolytic condenser, the test was carried out in two ways. First, In the case of accelerated life testing of condenser, the Arrhenius model is a way of life testing. Another way is to analyze the reliability of the failure data by the method of parametric data analysis. Eventually, life time by accelerated life test than a method of failure data analysis(Weibull distribution) was found to be slightly larger output.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.63-68
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• 2013

Some essential components in nuclear power plants are periodically inspected using non-destructive examinations, for example ultrasonic, eddy current and radiographic examinations, in order to determine their integrity. These components include nuclear power plant items such as vessels, containments, piping systems, pumps, valves, tubes and core support structure. Steam generator tubes have an important safety role because they constitute one of the primary barriers between the radioactive and non-radioactive sides of the nuclear power plant. There is potential that if a tube bursts while a plant is operating, radioactivity from the primary coolant system could escape directly to the atmosphere. Therefore, in-service inspections are critical in maintaining steam generator tube integrity. In general, the eddy current testing is widely used for the inspection of steam generator tubes due to its high inspection speed and flaw detectability on non-magnetic tubes. However, it is not easy to analyze correctly eddy current signals because they are influenced by many factors. Therefore, the performance of eddy current data analysts for steam generator tubing should be demonstrated comprehensively. In Korea, the performance of steam generator tubing analysts has been demonstrated using the Qualified Data Analyst program. This paper describes the performance demonstration program for steam generator tubing analysts and its implementation results in Korea. The pass rate of domestic analysts for this program was 71.4%.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.286-288
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• 2002

The rapid development of measurement systems for high power tests makes it possible to measure signals as well as analyze with the help of computer. Also, methods to evaluate such measurement systems are required recently. Uncertainty has been regarding as the most important factor in evaluating the measurement systems. Because of the character of the measurement systems for high power tests. the uncertainty shall be evaluated by each component. If the uncertainty evaluated by each component, it is convenient to evaluate total uncertainty of the measurement systems according to each component setting's combination. In this paper each component of high current measurement system of high power testing Dept. II in Korea Electrotechnology Research Institute is evaluated except sensors such as shunts and CTs. The total uncertainty of the measurement systems can be determined by that of each component including uncertainty of sensors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.334-339
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• 2012

A study on electrical and electronic equipment will occur in the atmosphere, which is essential to cut the power to prevent the waste of power by power measurement technology development and to develop the technology to do this operation is the main core of standby power to detect and block it and return the configured for software and hardware, while the actual construction to ensure stability through field testing and debugging of problems improved accordingly, as well as ease of installation and so it could be done while the test. In addition, in terms of basic hardware switching of standby power when blocking, reducing stress and ensure stable operation and circuit design, power off and back to ensure stable operation even when a protection circuit is applied.

• Progress in Superconductivity and Cryogenics
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• v.20 no.1
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• pp.11-14
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• 2018

High Temperature Superconducting (HTS) power cables are capable of transmitting bulk power without any loss compared to conventional copper cables. The major challenge in the design of such HTS cables is the high stresses (electro-thermal/electro-mechanical) developed at high voltages, high currents and cryogenic temperatures. The safe and reliable operation of HTS cables involves lots of instrumentation for monitoring, measurement, control and safe operation. In principle, a four probe method for resistance (RTD PT-100) is used for temperature measurements at various locations of HTS cable. The number of connecting leads required for this is four times that of the number of sensors. The present paper discusses a novel way of connecting 128 RTD sensors with the help of only 14 leads using a cold electronics based multiplexer board. LabVIEW 11.0 software was used for interfacing and displaying the readings of all the sensors on computer screen.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1462-1470
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• 2020

Reliability in safety-critical systems and equipment is of vital importance, so the probabilistic safety assessment (PSA) has been widely used for many years in the nuclear industry to address reliability in a quantitative manner. As many nuclear power plants (NPPs) become digitalized, evaluating the reliability of safety-critical software has become an emerging issue. Due to a lack of available methods, in many conventional PSA models only hardware reliability is addressed with the assumption that software reliability is perfect or very high compared to hardware reliability. This study focused on developing a new method of safety-critical software reliability quantification, derived from hardware-software integrated environment testing. Since the complexity of hardware and software interaction makes the possible number of test cases for exhaustive testing well beyond a practically achievable range, an importance-oriented testing method that assures the most efficient test coverage was developed. Application to the test of an actual NPP reactor protection system demonstrated the applicability of the developed method and provided insight into complex software-based system reliability.

• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.700-709
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• 2017

This work looks at the effect of changes in kinetic parameters on simultaneous reactivity insertions and beam tube flooding in a typical material testing reactor-type research reactor with low enriched high density ($U_3Si_2-Al$) fuel. Using a modified PARET code, various ramp reactivity insertions (from $0.1/0.5 s to $1.3/0.5 s) plus beam tube flooding ($0.5/0.25 s) accidents under uncontrolled conditions were analyzed to find their effects on peak power, net reactivity, and temperature. Then, the effects of changes in kinetic parameters including the Doppler coefficient, prompt neutron lifetime, and delayed neutron fractions on simultaneous reactivity insertion and beam tube flooding accidents were analyzed. Results show that the power peak values are significantly sensitive to the Doppler coefficient of the system in coupled accidents. The material testing reactor-type system under such a coupled accident is not very sensitive to changes in the prompt neutron life time; the core under such a coupled transient is not very sensitive to changes in the effective delayed neutron fraction.