• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.67-75
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• 2011

The development of electric vehicle power electronics system control, composed of DC-AC inverters and DC-DC converters, attract much research interest in the modern industry. A DC-AC inverter supplies the high-power motor torques of the propulsion system and utility loads of electric vehicles, whereas a DC-DC converter supplies the conventional low-power and low-voltage loads. However, the need for high-power bidirectional DC-DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. The nonlinear control of power converters is an active research area in the field of power electronics. This paper focuses on the use of the fuzzy sliding mode strategy as a control strategy for buck-boost DC-DC converter power supplies in electric vehicles. The proposed fuzzy controller specifies changes in control signals based on the surface and knowledge on surface changes to satisfy the sliding mode stability and attraction conditions. The performance of the proposed fuzzy sliding controller is compared to that of the classical sliding mode controller. The satisfactory simulation results show the efficiency of the proposed control law, which reduces the chattering phenomenon. Moreover, the obtained results prove the robustness of the proposed control law against variations in load resistance and input voltage in the studied converter.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.293-294
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• 2009

The spectral responsivity of solar cells has been measured under high background irradiance using an LED-based differential spectral responsivity Comparator (DSR-C). The comparator developed is fully automated and has some advantages: It does not need a chopper to modulate the light. Unlike the conventional method, it does not require a monochromator to select wavelength. It covers a wavelength range up to 1200 nm. The wavelength range of the comparator is limited by the spectral power distribution of the LEDs and the spectral responsivity of the standard detector. An active temperature control was utilized to meet the specified standard conditions of solar cell test. This work shows the effect of different levels of background irradiance on the spectral responsivity and the importance of same background irradiance for solar cell test as specified by the corresponding standard.

• Journal of Power Electronics
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• v.5 no.2
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• pp.83-98
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• 2005

As wind turbine technology and control has advanced over the last decade, this has led to a high penetration of wind turbines into the power system. Whether it be for a large wind turbine or an offshore wind farm with hundreds of MW power capacity, the electrical system has become more and more important in controlling the interaction between the mechanical system of the wind turbine and the main power system. The presence of power electronics in wind turbines improves their controllability with respect not only to its mechanical loads but also to its power quality. This paper presents an overview of a developed simulation platform for the modeling, design and optimization of wind turbines. The ability to simulate the dynamic behavior of wind turbines and the wind turbine grid interaction using four simulation tools (Matlab, Saber, DIgSILENT and HAWC) is investigated, improved and extended.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.370-371
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• 2006

The electric demand increase, financial need for new power plant constructions and environmental problem have led to search for more efficient energy Production and energy conservation technology. To minimize the construction of power plants and reduce total power consumption include installation of inverters to motors used for pumps and fans. However, the high price of inverters is the biggest obstacle to their wide use. Accordingly, to maximize the effect of energy saving by the expanded use of inverters, governmental economic support as ell as the analysis of energy saving effect. his paper presents he present state analysis of inverter DSM program and propose he improvement for activation of inverter DSM program.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.521-523
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• 2001

The electric demand increase, financial need for new power plant constructions and environmental problem have led to search for more efficient energy production and energy conservation technology. To minimize the construction of power plants and reduce total power consumption include installation of inverters to motors used for pumps and fans. However, the high price of Inverters is the biggest obstacle to their wide use. Accordingly, to maximize the effect of energy saving by the expanded use of inverters, governmental economic support as well as the analysis of energy saving effect. This paper presents the cost-effectiveness analysis for DSM program evaluation and case study to analyze inverter DSM program.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.149-154
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• 2020

This paper presented a design and a implementation of prototype model which is the smart diffuser device controlled by using Bluetooth technology in the smart phone. We used the ultrasonic waves oscillator so that the smart diffuser was able to spray oil into a device. The device was developed to find out the high brightness led colors switched during spraying the oil. By using the Li-Po battery of 40mAh capacity, we were able to design this portable device was prolonged available time to use and to solve the charging time problem. We realized the availability of prototype model which is using the Bluetooth Low Energy for operating the low power driving.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.24-24
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• 2003

Research activity in the III-V nitrides materials system has increased markedly in the past several years ever since high-brightness blue light-emitting diodes (LEDs) became commercially available. Despite of excellent optical properties of the GaN, however, inherently poor thermal property of the sapphire used as a substrate material n these devices may lead to thermal degradation of devices, especially during their high power operation. Therefore, dependable thermal analysis and packaging schemes of GaN-based LEDs are necessary for solid lighting applications under high power operation. In this paper, emphasis will be placed upon thermal design of GaN-based LEDs. Thermal measurements of LEDs on chip and packaging scale were performed using the liquid crystal thermographic technology and micro thermocouples for different bias conditions. By a series of optical arrangement, hot spots with specific transition temperatures were obtained with increasing input power. Thermal design of LEDS was made using the finite element method and analytical unit temperature profile approach with optimal boundary conditions. The experimental results were compared to the simulated data and the results agree well enough for the establishment of dependable prediction of thermal behavior in these devices. The paper will present a more detailed understanding of the thermal analysis of the GaN-based blue and white LEDs for high power applications.

• Electric Engineers Magazine
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• v.228 no.8
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• pp.43-48
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• 2001

Wide use of non-linear loads such as personal computers, monitors, laser printers, variable speed drives, UPS systems and other electronic equipment have led to harmonics becoming #1 issue in the electrical industry today. Commercial and Industrial building power distribution systems, designed for the old, linear-style loads especially when found in high densities. Some common power system problems include overloaded neutral conductors, overheated distribution transfOlmers, high neutral-to-ground voltage, poor power factor and distortion of the voltage waveform supplying these loads. The power quality problems, particularly high voltage distortion, have been known to cause equipment downtime due to malfunctions and component failure.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.5
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• pp.475-480
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• 2012

This study on the methode is easied to distinguish with emotional visual lighting on AtoN facility using 3colors LED, and which is controlled to on-off switching of approach light in shore or harbor. The identification have easied to provide a differentiation between the AtoN facility of red and white light and surrounding light in harbor both sides. And the integrated controller have designed to left-right and serial sequential lighting system for harbor guidance using the GPS synchronous or timer. There is expectation effect that is prevent a confusion about distinguish of facility by ship's operator and to beautify a night scene of harbor, which is expressed to emotional identification lighting and variable color lighting on AtoN body by vertical layer color lighting using LED. In addition, the performance of AtoN is implemented to display with guidance light the harbor safety message by morse code lighting. Effectiveness of system is enhanced that age and power consumption reduce by candle alternated high light LED.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.3
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• pp.262-272
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• 2015

An integrated two-in-one transformer applicable to PSUs for a 120 W LED TV is proposed. This transformer comprises a PFC inductor and an LLC transformer placed and integrated on an E-I-E type magnetic core. Performance is evaluated by observing the coupling coefficients of the proposed two-in-one transformer under various air gap topologies. Among the topologies studied, an integrated transformer with centered air gap shows stable operational characteristics with a minimized mutual coupling (interference). Furthermore, applicability of the proposed integrated transformer to PSUs for a 120 W LED TV is studied from the viewpoint of integrating different magnetic components into one core, resulting to low weight, low cost, and high power density.