• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.245-248
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• 2000

This paper presents the test and operation results of the domestic demonstration of the reactive power compensation device called STATCOM (STATic COMpensator). The object of the paper is to describe the reliability of the unit based on the extensive operation databases. By controlling reactive power, the technology offers utilities the opportunity for increased efficiency and their capabilities will permit transmission planners make the best use of their existing transmission resources STATCOM is a custom power device in a way and can be used in a similar way for the dynamic compensation of power transmission systems, mitigation of voltage flicker and improving the power factor. It is shown that the STATCOM has clear advantages in areas such as: mitigation of voltage flicker and improving power factor.

• Smart Structures and Systems
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• v.24 no.1
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• pp.83-94
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• 2019

Passive negative stiffness dampers (NSDs) that possess superior energy dissipation abilities, have been proved to be more efficient than commonly adopted passive viscous dampers in controlling stay cable vibrations. Recently, inertial mass dampers (IMDs) have attracted extensive attentions since their properties are similar to NSDs. It has been theoretically predicted that superior supplemental damping can be generated for a taut cable with an IMD. This paper aims to theoretically investigate the impact of the cable sag on the efficiency of an IMD in controlling stay cable vibrations, and experimentally validate superior vibration mitigation performance of the IMD. Both the numerical and asymptotic solutions were obtained for an inclined sag cable with an IMD installed close to the cable end. Based on the asymptotic solution, the cable attainable maximum modal damping ratio and the corresponding optimal damping coefficient of the IMD were derived for a given inertial mass. An electromagnetic IMD (EIMD) with adjustable inertial mass was developed to investigate the effects of inertial mass and cable sag on the vibration mitigation performance of two model cables with different sags through series of first modal free vibration tests. The results show that the sag generally reduces the attainable first modal damping ratio of the cable with a passive viscous damper, while tends to increase the cable maximum attainable modal damping ratio provided by the IMD. The cable sag also decreases the optimum damping coefficient of the IMD when the inertial mass is less than its optimal value. The theoretically predicted first modal damping ratio of the cable with an IMD, taking into account the sag generally, agrees well with that identified from experimental results, while it will be significantly overestimated with a taut-cable model, especially for the cable with large sag.

• The Journal of the Korea Contents Association
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• v.13 no.5
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• pp.19-27
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• 2013

This paper implements the standby power control system composed of a master device and slave devices. The standby power is managed by cutting power supply after controlling the relay of a slave device based on the authentication of master device's RFID card. RFID interface and wireless communication module are embedded in a master device, and one master device is linked with many slave devices in wireless. Each slave device executes the operation needed in power control independently. We implements the function of manual power on/off system in a slave device, and the function of user ID enrollment by switch manipulation in a master device. Also this system can communicate bidirectionally in wireless and runs on TinyOS. The result of experiment shows that the user authentication is executed in a master device and this authenticated information is transmitted to a slave device in wireless, and standby power is cutted by controlling the relay of a slave device. Installing this system in a building or an office, we can expect energy saving.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.365-372
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• 2014

In this paper, We implement a power-saving and efficient measures in buildings using the smart-meter. In order to save electric power energy, We propose an improved automatic power-factor controller(APFC) and demand control measures. This is achieved by controlling directly circuit breakers and the capacitor bank feeders in real time via a two-way smart-meter's ICT skills. Improved APFC is minimizing installation costs by series-parallel connecting heterologous capacitors to form a more diverse capacitor banking and controlling using the smart-meter. In order to suppress the demand power, We have designed a smart-meter with communication functions using Atmel's AVR465 and tested an operated lodging building for 24-hours. As a result, We made sure to always retained more than 95% power factor and did not occur over compensation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.7
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• pp.430-436
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• 2004

This paper presents an advanced control technique for power density maximization of the Brushless DC (BLDC) generator by using the linear tracking method. In a generator of given rating, the weight and size of the system affect the fuel consumption directly. Therefore, power density is one of the most important issues in a stand-alone generator. BLDC generator has high power density in the machine point of view and additional increases of power density by control means can be expected. Conventional rectification methods cannot achieve the maximum power possible because of hon-optimal current waveforms. The optimal current waveform to maximize power density and minimize machine size and weight in a nonsinusoidal power supply system has been derived, incorporated in a control system, and verified by simulation and experimental work. A new simple algebraic method has been proposed to accomplish the proposed control without an FFT which is time consuming and complicated.

• Journal of electromagnetic engineering and science
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• v.10 no.1
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• pp.6-12
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• 2010

In this paper, highly efficient class-F power amplifiers(PAs) with harmonic-controlling transmission lines(TLs) were built for cellular and WLAN applications at 840 MHz and 2.4 GHz each. Also, based on these single-band PAs, a dualband class-F PA was designed after a careful investigation into the harmonics of the two frequencies. The harmonic-controlling TL was designed for the class-F operation at dualband by switching the length of the shunt $\lambda$/4 TL part, while the series $\lambda$/4 TL is optimized for both frequencies. To verify the performance, two class-F PAs optimized at each frequency and a dualband class-F PA at the corresponding frequencies were built with the secondand the third-harmonic control circuits at each frequencies. As a result, the PA#1 at 840 MHz has a peak drain efficiency of 81.2 % with an output power of 24.4 dBm, while the PA#2 at 2.35 GHz shows a drain efficiency of 94.5 % with an output of 22.8 dBm. Finally, the dualband class-F PA#3 showed 60.5 % and 50.9 % drain efficiencies at 840 MHz and 2.4 GHz, with powers of 23.8 dBm and 19.62 dBm, respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.50-57
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• 2004

Two processors are generally used to drive the power circuits for controlling the dual motors independently. In this paper, we propose the new control scheme to drive dual inverters using only one controller with the aid of CAN network. The proposed system is very useful compared to conventional techniques especially in case of controlling the combined dual motors because the control algorithm can be implemented by the software program only without any additional processor or hardware interfacing. The proposed system is implemented and verified experimentally.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2109-2118
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• 2016

Based on the space vector pulse width modulation (SVPWM) theory, this paper realizes an easier SVPWM strategy, which is equivalently implemented by CBSPWM with zero-sequence voltage injection. The traditional SVPWM strategy has no effect on controlling the neutral-point voltage balance. In order to solve the neutral-point voltage unbalance problem for neutral-point-clamped (NPC) three-level inverters, this paper proposes a neutral-point voltage balance controller. The proposed controller realizes controlling the neutral-point voltage balance by dynamically calculating the offset superimposed to the three-phase modulation waves of an equivalent SVPWM strategy. Compared with the traditional SVPWM strategy, the proposed neutral-point voltage balance controller has a strong ability to balance the neutral-point voltage, has good steady-state performance, improves the output waveforms quality and is easy for digital implementation. An experiment has been carried out on a NPC three-level inverter prototype based on a digital signal processor-complex programmable logic device (DSP-CPLD). The obtained experimental results verify the effectiveness of the proposed neutral-point voltage balance controller.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.863-871
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• 2013

Control of pitch angle of turbine blades is among the controlling methods in the wind turbines; this measure is taken for managing mechanical power generated by wind turbine in different wind velocities. Taking into account the high significance of the power generated by wind turbine and due to the fact that better performance of pitch angle is followed by better quality of turbine-generated power, it is therefore crucially important to optimize the performance of this controller. In the current paper, a PI controller is primarily used to control the pitch angle, and then another controller is designed and replaces PI controller through applying a new strategy i.e. alternating two ADALINE neural networks. According to simulation results, performance of controlling system improves in terms of response speed, response ripple, and ultimately, steady tracing error. The highly significant feature of the proposed intelligent controller is the considerable stability against variations of wind velocity and system parameters.

• Journal of Korea Multimedia Society
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• v.21 no.5
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• pp.592-598
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• 2018

In wireless sensor networks where there is no centralized base station, each node has limited transmission range and the multi-hop routing for transmitting data to the destination is the one of the important technical issues. In particular, the wireless sensor network is not powered by external power source but operates by its own battery, so it is required to maximize the network life through efficient use of energy. To balance the power consumption, the residual power based adaptive power control is required in routing protocol. In this paper, we propose a routing protocol that prolongs the network lifetime by balancing the power consumption among the nodes by controlling the transmit power according to the residual power. We evaluate the proposed routing protocol using extensive simulation, and the results show that the proposed routing scheme can balance the power consumption and prolong network lifetime.