• Journal of Power Electronics
• /
• 제10권6호
• /
• pp.635-642
• /
• 2010

The paper presents a multimedia educational program of DC servo drives for distant learning with a special emphasis on sliding mode control. The program contains of three parts: animation, simulation and internet based measurement. The animation program explains the operation of DC motors, gives its time- and frequency-domain equations, transfer functions and the theoretical background necessary for controller design for DC servo motors. The simulation model of the DC servo motor and the controller can be designed by the students based on the animation program. The students can also test their controllers through the internet based measurement, which is the most important part from engineering point of view. After the measurements are executed, the students can download the measured data and compare them to the simulation results.

• 한국태양에너지학회 논문집
• /
• 제36권5호
• /
• pp.1-8
• /
• 2016

In this paper, we evaluated the effect of a silica-based Anti-Reflection(AR) coating for PV modules. The coating technique can be easily applied to large-scale PV modules at room temperature with improvements of the optical properties that is qualified by the optical transmission measurements on the coated cover glass of the modules. The power improvement of the large-scale PV modules shows the increasing about 2.4% at standard condition of the coating technique on average. To improve the AR coating effect of the PV modules, we have characterized the individual PV modules by the measurements of DC power output, modified performance ratio(PRm) and the regression. The results show that the significant improvements of the AR coating effect are 6.4%, 5.5% and 4.5% of increasing of the performances by using the measurements of DC power output, modified performance ratio(PRm) and the regression, respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 B
• /
• pp.676-678
• /
• 1995

The Paper describes a dc/nc power comparator for measurement of power. Based on a thermal principle, the instrument performs ac-dc transfer and absolute power and energy measurements in the range of currents from 0 to 5 A, voltages from 60 to 240 V, power factors from 0 to 1 and frequencies from 50 to 1000 Hz. The ac-dc transfer accuracy is better than 20 ppm at unity power factor and better than 50 ppm at 0.5 power factor.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1997년도 추계학술발표회논문집(1)
• /
• pp.58-63
• /
• 1997

This paper is concerned with an algorithm based on neural networks to calculate the axial power distribution using excore defector signals in the nuclear reactor core. The fundamental basis of the algorithm is that the detector response can be fairly accurately estimated using computational codes. In other words, the training set, which represents relationship between detector signals and axial power distributions, for the neural network can be obtained through calculations instead of measurements. Application of the new method to the Yonggwang nuclear power plant unit 3 (YGN-3) shows that it is superior to the current algorithm in place.

• 전기학회논문지
• /
• 제64권7호
• /
• pp.1130-1136
• /
• 2015

Most equipments which are used to measure the switching power of the turnout depend on imports. As the data is limited to the measurements of the switching power, it is said that the equipment is insufficient to check the errors of the turnout and the electrical point machine, and set up the data for operating and maintenance. We studied not only measurements of the switching power of all turnout being used in domestic but also the development of the turnout performance total analysis equipment which can measure switching time, voltage, and current etc. at the same time. Considering that switching power of the turnout is the most basic element to check the irregularities of the turnout, in this paper, we analyzed the irregularities of the turnout through correlation between switching power of the turnout, voltage, and current of the electrical point machine. Also we performed test in commercial railway line where the turnout of MJ81 type and NS type was installed. And it is said that the test results can be used as basic technologies for ICT based real-time diagnosis and monitoring of the turnout.

• 전력전자학회논문지
• /
• 제8권6호
• /
• pp.569-575
• /
• 2003

본 논문에서는 스위칭 전원장치의 효율을 높은 정밀도로 측정하고 분석학 수 있는 PC 기반 가상계측 기를 구성하여 운용한 결과를 보고한 것이다. 고전압 저전류 방식에 적합한 간접 측정방식과 저전압 대전류 전원장치에 적합한 직접 측정방식의 비교를 수행하였으며, 직접 측정방식에서는 측정 편차를 최소화시키기 위해서 보상 기능을 추가하였다. 구성된 가상계측기의 성능을 검증하기 위해서 50W급 통신기용 전원장치를 대상으로 특성을 계측하였다. 그 결과 기존의 방법에 비해서 전원장치의 정상상태 특성을 정확하게 평가할 수 있으며, 반복 측정 오차를 줄일 수 있을 뿐만 아니라, 실시간 측정이 가능하며, 측정 시간도 절약할 수 있었다.

• Journal of Power Electronics
• /
• 제18권6호
• /
• pp.1920-1929
• /
• 2018

In order to provide a source for nine phases suitable for 18-pulse ac to dc power, this paper proposes a new structure for a step-up asymmetrical delta-connected transformer for converting three-phase ac power to nine-phase ac power. The design allows for symmetry between the nine output voltages to improve the power quality of the supply current and to minimize the THD. The results show that this new structure proves the equality between the output voltages with $40^{\circ}-{\alpha}$ and $40^{\circ}+{\alpha}$ phase shifting and produces symmetrical output currents. This result in the elimination of harmonics in the network current and provides a simulated THD that is equal to 5.12 %. An experimental prototype of the step-up asymmetrical delta-autotransformer is developed in the laboratory and the obtained results give a network current with a THD that is equal to 5.35%. Furthermore, a finite element analysis with a 3D magnetic field model is made based on the dimensions of the 4kVA, 400 V laboratory prototype three-phase with three-limb delta-autotransformer with a six-stacked-core in each limb. The magnetic distribution flux, field intensity and magnetic energy are carried out under open-circuit operation or load-loss.

• KEPCO Journal on Electric Power and Energy
• /
• 제5권2호
• /
• pp.103-111
• /
• 2019

The combined cycle plant is an integration of gas turbine and steam turbine, combining the advantages of both cycles. It recovers the heat energy from gas turbine exhaust to use it to generate steam. The heat recovery steam generator plays a crucial role in combined cycle plants, providing the link between the gas turbine and the steam turbine. Simulation of the performance of the HRSG is required to study its effect on the entire cycle and system. Computational fluid dynamics has potential to become a useful to validate the performance of the HRSG. In this study a solver has been implemented in the open source code, OpenFOAM, for combustion simulation in the heat recovery steam generator. The solver is based on the steady laminar flamelet model to simulate detailed chemical reaction mechanism. Thereafter, the solver is used for simulation of HRSG system. Three cases with varying fuel injections and gas turbine exhaust gas flow rates were simulated and the results were compared with measurements at the system outlet. Predicted temperature and emissions and those from measurements showed the same trend and in quantitative agreement.

• 한국유체기계학회 논문집
• /
• 제8권5호
• /
• pp.13-21
• /
• 2005

This study aims to analyze operating performance of a micro gas turbine with the aid of detailed measurements of various system parameters. In addition to embedded measurements, parameters such as exhaust temperatures, engine inlet temperatures and fuel flow rates are measured. Variations in measured data and estimated performance parameters are analyzed. Those data are processed to calculate losses along the power transmission line and the net gas turbine performance (power and efficiency based on the gas turbine shaft end) is isolated from the overall system performance. A method to estimate characteristic parameters such as component efficiencies, based on the comparison between measured and predicted performance data, is suggested and exemplified for the full load condition.

• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 2003년도 International Symposium on Clean Environment
• /
• pp.69-72
• /
• 2003

The meteorological model, CALMET, and its plume dispersion model, CALPUFF, were used in order to simulate the dispersion of $SO_2$ emitted from Yatagan Power Plant and its effect on Yatagan district in the episodic event on December 2 and 3, 2000. It is found that south westerly and light winds and the nighttime surface inversion layers lead to accumulation of pollutants over Yatagan district. The results are compared with the measurements done by Local Environmental Authorities of Mu la. The simulation results indicate that the maximum ground level concentrations were found northeast from the source, which agrees with experimental measurement. On the other hand, the magnitude of results obtained with the model shows some differences compared with experimental measurements.