• Journal of Power Electronics
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• v.13 no.4
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• pp.692-700
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• 2013

This paper discusses the design of a novel synchronous reference frame (SRF) method that can extract the reference compensating current for single-phase shunt active power filters (APFs). Unlike previous SRF studies, the proposed method has an innovative feature that does not require a fictitious current signal. Other key features of the proposed strategy include frequency-independent operation, accurate reference current extraction, and relatively fast transient response. The effectiveness of the proposed method is investigated by conducting a detailed mathematical analysis. Results of the analysis confirm the superior performance of the suggested approach. Theoretical evaluations are confirmed by the experimental results.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1088-1091
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• 2009

A boost converter with charge-recycling technique fabricated by $0.25{\mu}m$ CMOS BCD process can provide different supply voltages to drive series RGB LEDs in sequence for reducing the power consumption on the constant current generator. The proposed technique stores and restores extra energy to improve the efficiency, as well as enhances the reference tracking response. Experimental results show that the period of reference-tracking response can be improved. When the load current is 100mA, the periods of reference down-tracking and uptracking are smaller than $10{\mu}s$ and $20{\mu}s$, respectively. Experimental results demonstrate fast and efficient reference tracking performance is achieved.

• Nutrition Research and Practice
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• v.11 no.1
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• pp.51-56
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• 2017

BACKGROUND/OBJECTIVES: The purpose of this study was to assess the accuracy of a dietary reference intake (DRI) predictive equation for estimated energy requirements (EER) in female college tennis athletes and non-athlete students using doubly labeled water (DLW) as a reference method. MATERIALS/METHODS: Fifteen female college students, including eight tennis athletes and seven non-athlete subjects (aged between 19 to 24 years), were involved in the study. Subjects' total energy expenditure (TEE) was measured by the DLW method, and EER were calculated using the DRI predictive equation. The accuracy of this equation was assessed by comparing the EER calculated using the DRI predictive equation ($EER_{DRI}$) and TEE measured by the DLW method ($TEE_{DLW}$) based on calculation of percentage difference mean and percentage of accurate prediction. The agreement between the two methods was assessed by the Bland-Altman method. RESULTS: The percentage difference mean between the methods was -1.1% in athletes and 1.8% in non-athlete subjects, whereas the percentage of accurate prediction was 37.5% and 85.7%, respectively. In the case of athletic subjects, the DRI predictive equation showed a clear bias negatively proportional to the subjects' TEE. CONCLUSIONS: The results from this study suggest that the DRI predictive equation could be used to obtain EER in non-athlete female college students at a group level. However, this equation would be difficult to use in the case of athletes at the group and individual levels. The development of a new and more appropriate equation for the prediction of energy expenditure in athletes is proposed.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1096-1103
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• 2014

This paper proposes a novel strategy for attenuating the output power fluctuation of the wind farm (WF) in a range of tens of seconds delivered to the grid, where the kinetic energy caused by the large inertia of the wind turbine systems is utilized. A control scheme of the two-level structure is applied to control the wind farm, which consists of a supervisory control of the wind farm and individual wind turbine controls. The supervisory control generates the output power reference of the wind farm, which is filtered out from the available power extracted from the wind by a low-pass filter (LPF). A lead-lag compensator is used for compensating for the phase delay of the output power reference compared with the available power. By this control strategy, when the reference power is lower than the maximum available power, some of individual wind turbines are operated in the storing mode of the kinetic energy by increasing the turbine speeds. Then, these individual wind turbines release the kinetic power by reducing the turbine speed, when the power command is higher than the available power. In addition, the pitch angle control systems of the wind turbines are also employed to limit the turbine speed not higher than the limitation value during the storing mode of kinetic energy. For coordinating the de-rated operation of the WT and the storing or releasing modes of the kinetic energy, the output power fluctuations are reduced by about 20%. The PSCAD/EMTDC simulations have been carried out for a 10-MW wind farm equipped with the permanent-magnet synchronous generator (PMSG) to verify the validity of the proposed method.

• Nutrition Research and Practice
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• v.11 no.4
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• pp.300-306
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• 2017

BACKGROUND/OBJECTIVES: The doubly labeled water (DLW) method is considered the gold standard for the measurement of total energy expenditure (TEE), which serves to estimate energy requirements. This study evaluated the accuracy of predictive dietary reference intake (DRI) equations for determining the estimated energy requirements (EER) of Korean adults by using the DLW as a reference method. SUBJECTS/METHODS: Seventy-one participants (35 men and 36 women) aged between 20 and 49 years were included in the study. The subjects' EER, calculated by using the DRI equation ($EER_{DRI}$), was compared with their TEE measured by the DLW method ($TEE_{DLW}$). RESULTS: The DRI equations for EER underestimated TEE by -36.3 kcal/day (-1.3%) in men and -104.5 kcal/day (-4.9%) in women. The percentages of accurate predictions among subjects were 77.1% in men and 62.9% in women. There was a strong linear correlation between $EER_{DRI}$ and $TEE_{DLW}$ (r = 0.783, P < 0.001 in men and r = 0.810, P < 0.001 in women). CONCLUSIONS: The present study supports the use of DRI prediction equations to determine EER in Korean adults. More studies are needed to confirm our results and to assess the validity of these equations in other population groups, including children, adolescents, and older adults.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.12
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• pp.1667-1673
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• 2000

The climate and marketing system of raw milk in Taiwan create problems in balance feeding of protein and energy in lactating cows in Taiwan. Level of urea nitrogen both in bulk milk and serum reflects ruminal protein degradation and post-ruminal protein provision, whereas milk protein concentration responds to dietary energy intake and bacterial protein production in the rumen. Establishment of a range of reference standards in milk protein and urea nitrogen levels can be applied as a noninvasive economical feeding guide to monitor the balance of protein and energy intake. Standard reference levels of 3.0% milk protein and 11-17 mg/dL milk urea nitrogen (MUN) were established. Level of milk protein below 3.0% is regarded as indicating inadequate dietary energy whereas MUN below or above the range is regarded as a deficiency or surplus in dietary protein. Results from analysis of bulk a milk samples collected from 174 dairy herds over Taiwan showed that only one quarter (25.29%) of the herds received a balanced intake of protein and energy, 33.33% adequate protein with energy inadequate, 22.99% herds in protein surplus with energy inadequate, 10.35% herds in protein surplus with energy adequate, 4.6% protein deficiency with energy adequate, and 3.45% herds with both protein and energy inadequate. Energy inadequate herds accounted for 60% of the total dairy herds in Taiwan with 56% adequate, 38% surplus and 6% inadequate in protein. In comparing milk sampled from bulk milk on different seasons from Lee-Kang area in the southern Taiwan, the concentrations of milk fat and milk protein were significantly higher in the cool season (February) than in the warm season (August) (p<0.05), whereas the urea nitrogen in the milk was significantly lower in the cool season than in the warm season (p<0.05). This indicated that lactating cows had excess protein and/or inadequate energy intake in the warm season in this area. It appears that the major problem feeding in lactating cows is energy intake shortage, especially during the warm season in Taiwan.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.37-38
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• 2009

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.2
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• pp.59-64
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• 1983

This paper deals with the transient energy method of transient stability analysis of multi-machine power system by improving the transfer conductance, the kinetic energy and the critical transient energy. The tranfer conductance is considered more correctly, the generators of system are seperated to two states (critical and the rest state)and the correction term of critical transient energy (to reference point) is added. This analysis is performed by digital computer simulation and the application of this method to two model systems has shown its superiority to other available methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2503-2510
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• 2015

This paper presents a single-phase energy measurement IC to measure electric power quantities. The entire IC includes two programmable gain amplifiers (PGAs), two ${\sum}{\Delta}$ modulators, a reference circuit, a low-dropout (LDO) regulator, a temperature sensor, a filter unit, a computation engine, a calibration control unit, registers, and an external interface block. The proposed energy measurement IC is fabricated with $0.18-{\mu}m$ CMOS technology and housed in a 32-pin quad-flat no-leads (QFN) package. It operates at a clock speed of 4,096 kHz and consumes 10 mW in 3.3 V supply.

• Journal of the Korean Solar Energy Society
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• v.29 no.2
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• pp.70-75
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• 2009

In this experiment, we did sampling 6 kinds of photovoltaic modules and analyzed the discrepancy of measurement results between l laboratory and 4 PV makers to have performance repeatability at Standard Test Condition(STC) condition. From the KIER's results, Korea's standard test laboratory, other laboratory showed -10% measurement variation. The causes came from correction of reference cell, test condition and the state of skill. Form the comparison test, we analyzed the problems. But three PV maker reduced measurement variation, other one PV maker and one test laboratory didn't improve the problems of correction of reference cell, test condition and the state of skill. Also, High Efficiency Module had a big discrepancy of -10.0$\sim$-6.2% among 3 laboratories which have a less than 10msec light pulse duration time. This made low spectrum response speed so the Fill Factor decreased maximum output power under 10msec light pulse duration time