• ETRI Journal
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• v.23 no.2
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• pp.77-84
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• 2001

The detection of open defects in CMOS SRAM has been a time consuming process. This paper proposes a new dynamic power supply current testing method to detect open defects in CMOS SRAM cells. By monitoring a dynamic current pulse during a transition write operation or a read operation, open defects can be detected. In order to measure the dynamic power supply current pulse, a current monitoring circuit with low hardware overhead is developed. Using the sensor, the new testing method does not require any additional test sequence. The results show that the new test method is very efficient compared with other testing methods. Therefore, the new testing method is very attractive.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1068-1075
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• 2006

Flow-able backfill is known as soil-cement slurry, void fill, and controlled low-strength material (CLSM). The benefits of CLSM include reduced equipment costs, faster construction, re-excavation in the future, and the ability to place material in confined spaces such as narrow parts nearly impossible for compaction or perimeter of underground power cables. A review of some recent full-scale tests carried out by KEPRI on slurry backfill materials for application in underground power cable was presented. Based on this research, applicability was assessed and compare to results of laboratory tests for improved slurry materials with optimal mixture contents.

• New & Renewable Energy
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• v.17 no.3
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• pp.16-23
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• 2021

Recently, the Korean government announced a plan to activate renewable energies, with focus on clean energy sources such as solar and wind power as the core and the goal of achieving carbon neutrality by 2050. Unlike other photovoltaic (PV) systems, offshore PV installations are advantageous for large-scale expansion because of the ease of securing sites; they also enable lowering the power generation costs based on construction of large-scale power facilities of megawatt class or higher owing to low noise and landscape damage. However, any power generation should proceed with consideration of the special environmental conditions of the ocean. Above all, when installing large-scale facilities, it is important to reduce fluctuations of the structure and secure stability to actively respond to waves. This study is concerned with the development of a floating body technology that actively responds to waves so as to enable commercialization of offshore solar power. A unit platform for research and development on offshore PV generation was installed in the Saemangeum sea, and the structural fluctuations and stability were analyzed to ensure conformity with the major performance indicators.

• Fire Science and Engineering
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• v.27 no.5
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• pp.15-18
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• 2013

This paper is concerned with the Performance and Reliability Certification for fire detection system in outdoor area such small and middle sized cultural assets, natural monument and outdoor facilities. Especially, if a fire were to occur in vulnerable area, it is difficulty to detect a fire. therefore we propose a high efficiency and low cost unmanned fire detection system in capable of an early detection regardless spontaneously fire or firebug. for Adoption of Intelligent Fire Detection System with movable and unmanned function breaking from the existing Conventional Fire Detection System, this Range of R&D includes the Performance test, Function test, Field test, Flame Detection test and EMI/EMS Compliance test. the Result data of Performance test, Function test and Field test is generally good during 3 months. also we checked that thermal variation test and EMI/EMS compliance test are good result data within allowable range. As a result of general test, we verified improvement results that the measure distance of fire detection extend 75 m, the Power of waiting time increase 4 hours, the Power of operation time increase 3 days and the context awareness with video as well as sensors.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.4
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• pp.14-22
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• 2005

The safety factor of hydraulic piston pumps & motors due to high pressurization, high speedization and low weight/volume realization to enhance the output density shows a tendency to decrease. Therefore more effective test methods are necessary to predict the exact life. The failure of hydraulic pumps & motors operating in high pressure and high speed mainly occurs in piston-shoe assemblies, and the major failure mode is wearout of the shoe surface. The sensitive parameters in the endurance life test are speed, pressure and temperature, and the failure production increases in proportion to the operating time. In this research, the authors propose the combined accelerated life test model using the analysis method of the combined accelerated life test results of piston-shoe assemblies by applying simultaneously high speed, high pressure and high temperature in accordance with variation of speed, pressure and temperature to reduce the life test time.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.29-35
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• 2008

This study is conducted to provide the proper analysis method to evaluate the stability of a container crane under wind load. Two analysis method, namely structure analysis and fluid-structure interaction, are adopted to evaluate the stability of a container crane in this investigation. To evaluate the effect of wind load on the stability of the crane, 50-ton class container crane widely used in container terminals is adopted for analysis model and 19-values are considered for wind direction as design parameter. We conduct structure analysis and fluid-structure interaction for a container crane with respect to the wind direction using ANSYS and CFX. Then we compare the uplift forces yielded from two analysis with it yielded from wind tunnel test. The results are as follows: 1) A correlation coefficient between structure analysis and wind tunnel test is lower than 0.65(as $0.29{\sim}0.57$), but between fluid-structure interaction and wind tunnel test is higher than 0.65(as $0.78{\sim}0.86$). 2) There is low correlation between structure analysis and wind tunnel test but very high correlation between fluid-structure interaction and wind tunnel test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1482-1489
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• 2007

In this paper, characteristics of infrasound and low-frequency noise emission from large modern wind turbines are experimentally investigated. The sound measurement procedures of IEC 61400-11 and ISO 7196 are utilized to field test and evaluation of noise emission from each of 1.5 MW and 660 kW wind turbines using the stall regulation and the pitch control for the power regulation, respectively. It was found that the G-weighted SPLs of low-frequency noise including infrasound shows positive correlation with the wind speeds, irrespective of methods of power regulation. This highlights the potential complaint of local community against the infrasound and low-frequency noise of wind turbines. The comparison of measured data with the existing hearing thresholds and criteria curves shows that it is highly probable that the low-frequency noise from the 1.5 MW and 660 kW wind turbines in the frequency range over 30 Hz leads to the psychological complaint of ordinary adults, and that the infrasound in the frequency range from 5 Hz to 8 Hz causes the complaint by rattling the house fitting such as doors and windows.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.214-217
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• 2008

To detect partial discharge of 154kV joint box, we have made experiment by using the HFCT sensor. Generally the signals which are detected in partial discharge test of underground power transmission cable are accompanied with both noises of high voltage and noises of surrounding Power cable. The most noise in near to end part of joint box is corona, beside other noises flowed from surrounding area. Partial discharge test is difficulty due to these noises. First, we test reliability on both injection of calibration signal in NJB and removal of low frequency. After that, we had analyzed frequencies by measuring signals in IJB with 300[m] distance from NJB. Also we had measured S/N ratio by using the indirected injection method of calibration signal in IJB. In this experiment, two measurement methods were difference of detection acquisition, but these had the equal frequency properties.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.7
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• pp.413-417
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• 2013

The organic Rankine Cycle (ORC) uses a kind of refrigerant as a working fluid that evaporates at relatively low temperature, as the Rankine Cycle uses superheated steam as the working fluid. A small scale ORC test bench was installed, and two different working fluids (R245fa and R134a) were injected into the test bench. The test bench was in operation with the two different working fluids under the same conditions. The effects against the system performance from the different working fluids were analysed, and root causes were identified. Other factors reflecting the power generation efficiency were also found. A conclusion was drawn, that R245fa makes the system perform better, than R134a.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1370-1376
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• 2008

The structure of railroad or subway is that low fare transportation system of the large traffic volume. Like this structure is subjected to the cyclic load of moving vehicle. Consequently the result of the settlement analysis or plastic deformation prediction of railroad bed could be used as an important factor in safety of the railroad. The results of cyclic triaxial test were used in the numerical analysis of power model which Li and Selig(1994) developed. The soil samples were obtained from the construction site of railroad. Cyclic triaxial test was conducted with the variation of the magnitude of cyclic load and soil types. The large magnitude of plastic deformation in the railroad bed is caused of structure failure of the railroad.