• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.838-844
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• 2022

In this paper, an experimental study was conducted on the energy efficiency ratio of performance for air source heat pump. The energy efficiency ratio presents the operating efficiency of heat pump performance. In order to improve reliability in the energy efficiency ratio test of air source heat pump, the measurement uncertainty of the instrument was estimated. Measurement uncertainty refers to the uncertainty of a measurement, estimates the range in which the expected value of the measurement can be within a certain confidence level, and suggests a range in which the measured representative value is incorrect. The measurement uncertainty for the energy efficiency ratio test of air source heat pump was calculated and the measured results were presented.

• Journal of Radiation Industry
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• v.17 no.4
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• pp.471-479
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• 2023

In In-situ radioactivity measurement techniques, efficiency calibration models use predefined models to simulate a sample's geometry and radioactivity distribution. However, simplified efficiency calibration models lead to uncertainties in the efficiency curves, which in turn affect the radioactivity concentration results. This study aims to develop an efficiency calibration optimization methodology to improve the accuracy of in-situ gamma radiation measurements for byproducts from industrial facilities. To accomplish the objective, a drive mechanism for rotational measurement of an byproduct simulator and a sample was constructed. Using ISOCS, an efficiency calibration model of the designed object was generated. Then, the sensitivity analysis of the efficiency calibration model was performed, and the efficiency curve of the efficiency calibration model was optimized using the sensitivity analysis results. Finally, the radiation concentration of the simulated subject was estimated, compared, and evaluated with the designed certification value. For the sensitivity assessment of the influencing factors of the efficiency calibration model, the ISOCS Uncertainty Estimator was used for the horizontal and vertical size and density of the measured object. The standard deviation of the measurement efficiency as a function of the longitudinal size and density of the efficiency calibration model decreased with increasing energy region. When using the optimized efficiency calibration model, the measurement efficiency using IUE was improved compared to the measurement efficiency using ISOCS at the energy of ²²⁸Ac (911 keV) for the nuclide under analysis. Using the ISOCS efficiency calibration method, the difference between the measured radiation concentration and the design value for each simulated subject measurement direction was 4.1% (1% to 10%) on average. The difference between the estimated radioactivity concentration and the design value was 3.6% (1~8%) on average when using the ISOCS IUE efficiency calibration method, which was closer to the design value than the efficiency calibration method using ISOCS. In other words, the estimated radioactivity concentration using the optimized efficiency curve was similar to the designed radioactivity concentration. The results of this study can be utilized as the main basis for the development of regulatory technologies for the treatment and disposal of waste generated during the operation, maintenance, and facility replacement of domestic byproduct generation facilities.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.143-148
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• 2014

This paper proposes a novel efficiency measurement method without dynamometer. In case of small motor, the measurement of efficiency is not easy because the percentage of mechanical loss is comparably huge and the mechanical loss is not easy to be measured. In this paper, the authors proposes a method which can measure the efficiency with two test motors. This method can be useful to engineers who study small electrical motors.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.234-242
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• 2003

The full energy peak efficiency of a hyper pure germanium (HPGe) detector was calibrated in a wide energy range from 0.06 to 11 MeV. Both the experimental technique and the Monte Carlo method were used for the efficiency calibration. The measurement was performed using the standard radioisotopes in the low energy region of $60{\sim}1408$ keV, which was further extended up to 11 MeV by using the $^{14}N(n,r)\;and\;^{35}Cl(n,r)$ reactions. The GEANT Monte Carlo code was used for efficiency calculation. The calculated efficiency had the same dependency on the r-ray energy with the measurement, and the discrepancy between the calculation and the measurement was minimized by fine-tuning of the detector geometry. From the calculated result, the efficiency curve of the HPGe detector was reliably determined particularly in the high energy region above several MeV, where the number of measured efficiency points is relatively small despite the wide energy region. The calculated efficiency agreed with the measurement within about $7\%$. In addition to the efficiency calculation, the origin of the local minimum near 600 keV on the efficiency curve was analyzed as a general characteristics of a HPGe detector.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.205.1-205.1
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• 2011

This study concerns a low head and kaplan turbine efficiency measurement using the acoustic scintillation flow meter(ASFM). The ASFM is one of absolute discharge measurement methods because it measures velocity-area of discharge with couples of transducers. This study shows that the highest efficiency of turbine is 87.7% and the efficiency is 85.8% in the rated output(600kW). The test result is reliable because the efficiency trend from this test is similar to the result of index test conducted in 1986. In this paper, the principle, measurement methods, application and test procedures of the test are discussed.

• Plant Journal
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• v.17 no.1
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• pp.50-57
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• 2021

It is very difficult to accurately calculate efficiency of each accessory device constituting the pump system and pump efficiency by the Conventional efficiency measurement method only. Therefore, this study introduced the lastest Thermodynamic pump efficiency measurement method in the district heating pump system for the first time in Korea. As a result, data uncertainty was high by the Conventional method, but the pump and Hydraulic Coupling efficiency values applied the Thermodynamic and Conventional method parallel measurement data were able to derive meaningful results that verified the reliability and adequancy of the pump performance measurement method by performing complementary roles. In additon, as a result of applying the Thermodynamic method to the distirct heating pump system, despite the high temperature environment of up to 120 ℃, it was possible to verify the reliability of the Thermodynamic method, such as high stable data mesurement, and durability of the measurement equipment.

• IEMEK Journal of Embedded Systems and Applications
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• v.18 no.1
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• pp.9-17
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• 2023

This paper relates to the development of a device for measuring the efficiency of a solar panel based on a variable constant current, and proposed a standard for reuse of the solar panel. By applying a variable constant current circuit to a solar panel efficiency measuring device, it was easy to apply a maximum power point tracking (MPPT) algorithm. In addition, a load dispersion method was applied to measure the efficiency of a high-capacity solar panel. and it is possible to solve a problematic thermal runaway during a MOSFET parallel operation by applying the load dispersion method. As a result of the experiment, the solar panel efficiency measuring device was able to accommodate a large solar panel of 350W, which is the maximum measurement goal. In this paper, the validity was confirmed through the 310W solar panel efficiency measurement experiment collected after removal.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.73-78
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• 2016

3phase induction motor consumes 40% of national electric power. so It is one of the most important electric device for the national power policy. The efficiency measurement is carried out by IEC standards. After the temperature rise test, It's difficult to measure the winding resistance immediately. because of inertia and power cut-off time. Therefore, IEC standards suggest the measurement time. But during the measurement time, the winding temperature cools down. It causes the value of winding resistance is variable. Several conditions which possibly occurred by the measurement time of IEC 60034-1 are suggested. and The efficiency evaluation of 3phase induction motors is carried out by IEC 60034-2-1 with the several conditions. As the results, we find out the winding resistance rapidly goes down within 15 sec. so It proves that the winding resistance should be measured within 15 sec. for the efficiency evaluating of 3phase induction motor.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.537-544
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• 2005

This paper presents the efficiency measurement and energy analysis for a parallel HEY. Using the HEV test rig, the efficiency of each powertrain component is measured for a given driving cycle including the regenerative braking system. Accompanied by the efficiency measurements, a detailed energy analysis is performed. Based on the efficiency measurement and energy analysis, a HEV performance simulator is developed. Using the simulator, the HEV performance is evaluated for a mild hybrid system. It is expected that the HEV simulator developed can be used to obtain further optimization potentials.

• IE interfaces
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• v.22 no.4
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• pp.336-346
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• 2009

One of primary assumptions on DEA is that all DMUs for evaluation should be homogeneous. In comparative analysis among DMUs with relative efficiency measurement, it should be evaluated under identical conditions by ruling out external environmental influences. In this study, a measurement of innovation efficiency using the three-stage approach is performed. The approach employs DEA to measure relative efficiency and Tobit regressions to control external variables affecting innovation activity. The approach applied to firms in Korean Innovation Survey: Service Sector 2003 and 2006. Final efficiency scores of the approach represent net efficiency of the innovation. This study found that there is a increasing on technical efficiency of third stage, and it has difference with first stage significantly. Besides, a decrease on standard deviation of third stage is found. It means DMUs biased lower due to unfavorable condition and ones biased higher due to favorable condition are fallen into an identical operating environment through the approach. A measurement of net efficiency, excluding external effects, ensures the homogeneity of DMUs so that improves the reliability in terms of its analysis results. This study is expected to provide a direction and to be a valuable reference to further evaluation of innovation performance in Korean service sector.