• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.4
• /
• pp.277-282
• /
• 2014

Hybrid transformer means the distribution transformer, one of multi-function transformer equipped with the enhancement function of harmonics and unbalance. In other words, since existing transformer are equipped simply with transformation function only, a separated electric facility should be additionally installed in order to reduce the mutual harmonics and unbalance. Meanwhile, since hybrid transformer can perform the reduction of harmonics and unbalance as well as transformation function simultaneously through zigzag winding, it doesn't need any additional electric facility. This study addressed the issue of developing and testing the performance of a generator that would reduce the harmonics supplied to the grid when grid-connected with the output of a photovoltaic inverter for photovoltaic generation system.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.2035-2037
• /
• 2000

This paper describes the effect of lightning impulse current on deterioration of ZnO blocks for distribution arrester. In this study. a multiple-lightning impulse current generator which can produce quadruple 8/20 ${\mu}s$ 5 kA is designed and fabricated, and total energy applied to the arrester block at each pulse is about 1,217 J. The experimental results indicate that the type of arresters are more vulnerable to deteriorate or damage at multiple-lightning impulse current.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1120-1125
• /
• 2004

Welding characteristics of STS304 stainless steel and Inconel 600 using a continuous wave Nd:YAG laser are experimentally investigated. Alloy 600 being used in steam generator tubing of pressurized water reactor(PWR) exposed to some corrosion environment, stress corrosion cracking can occur on this material. Presented here are the results from a series of experiments in which dissimilar metal welds were made using the gas tungsten arc welding process with pure argon shielding gas. But It is well known that solidification cracking susceptibility of austenitic alloys depends on the solidification temperature range and amount/distribution of solute rich liquid that exists at the terminal stages of solidification. An experimental study was conducted to determine effects of welding parameters and to optimize those parameters that have the most influence on eliminating or reducing the extent welding zone formation at dissimilar metal welds.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1510-1515
• /
• 2004

The effects of additive ions on the generation of metallic nanoparticles were evaluated using a corona induced supersonic nozzle. Applying the corona discharge to the nanoparticle generator, a tungsten needle and the supersonic nozzle are used as an anode electrode and a cathode electrode respectively. The corona ions act as nuclei for the silver vapor condensation. The ion density was controlled precisely as varying the applied voltage between electrode and nozzle. The mean diameter of the silver particle decreases as the ion density increases. However, the number concentration of the silver particle tended to increase with the ion density. The size distribution is more uniform as the ion density increases.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.10 no.4
• /
• pp.177-183
• /
• 2002

A pulsed tracer gas technique is applied to measure the distributions of local mean age and local mean residual-life-time of air in a half-scale experimental chamber, The airflow patterns in the chamber are visualized by a Helium bubble generator for three different exhaust locations. A supply slot is located at the top of a right wall, and an exhaust slot is at either bottom-left (Case 1), bottom-right (Case 2), or top-left (Case 3) location. Results show that the distributions of local mean age and local mean residual-life-time are different from each other, but both of them are closely related to the airflow pattern in the space. Included are discussions on explaining the variations of overall room ventilation effectiveness depending upon airflow rates for three different supply-exhaust configurations.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.12 no.1
• /
• pp.27-34
• /
• 2017

The signal transmitted from radar is not reflected from a single point when the signal reflected by complex target. Resultantly, the amplitude and phase of the received signal can be changed because the target has lots of scatterers. The changes of the amplitude and the phase mean Glint and RCS, respectively. Although the Glint and RCS that caused by the same scatters are uncorrelated, however, they are not independent completely. Therefore, this paper proposes a method for generating the Glint and RCS by using same random number generator. And the time correlations of the Glint and RCS are respectively implemented in frequency domain by using each power spectral density of them.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.3
• /
• pp.330-335
• /
• 1999

Recently, there a lot of activities on the researches that implement many kinds of control system using power lines. To implement that, it is desirable to use hybrid PSK model because it takes advantage of PSK and DPSK which has a low-bit-error rate. In this parer, we implement the transmitter of this model. Because the power line is not designed for the data communication, we separated the signal generator circuit and the signal loading circuit so that minimized noises from outside. Also, to make it easy on the experiments, most of process are performed by software. As a result, transmitting a high frequency signal on the power line made no effects on the electrical devices.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.4
• /
• pp.1483-1493
• /
• 2018

Recently, more power facilities are needed to cope with the increasing electric demand. However, the additional construction of generators, transmission and distribution installations is not easy because of environmental problems and citizen's complaints. Under this circumstance, a microgrid system with distributed renewable resources emerges as an alternative of the traditional power systems. Moreover, the configuration of power system changes with more DC loads and more DC installations. This paper is written to introduce an idea of a genetic algorithm-based solution to determine the optimal capacity of the distributed generators depending on the types of system configuration: AC-link, DC-link and Hybrid-link types. In this paper, photovoltaic, wind turbine, energy storage system and diesel generator are considered as distributed generators and the feasibility of the proposed algorithm is verified by comparing the calculated capacity of each distributed resource with HOMER simulation results for 3 types of system configuration.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.1205-1207
• /
• 2004

AC plasma power supply is used to control a ozone generator and a air pollution gas. AC plasma power supply is composed of power semiconductor switch devices and control board adapted SHE(Selected Harmonic Elimination) PWM method. AC plasma power supply with sinusoidal VVVF(variable voltage and variable frequency) is realized. Its output voltage range is from 0 [V] to 20[kV] and output frequency range is from 8[kHz] to 20[kHz]. Using proposed system, AC high voltage and high frequency discharge is tested in the DBD(dieletric barrier discharge) reactor, and the space distribution of a its non-thermal plasma is observed. In spite of the increasement of voltage and frequency, the proposed system have a stable operation characteristics. It is verified by the experimental results.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.633-635
• /
• 2007

To cope with increasing power demand in metropolitan area, the power system in Korea has equipped with unit generator of large capacity, high density and uneven distribution, and transmission line of long distance, large capacity and high voltage. As the power system growing up enormous, it has become difficult to maintain the standard voltage in case of radical fluctuation of load or severe change of voltage by power system fault for its weakness of responsive characteristics although the power condenser has been installed to solve the unstability by lack of reactive power. Consequently, we review harmonic wave production and control characteristics to solve unstability problem of voltage in northern metropolitan, to reduce transmission restriction cost and to minimize load shedding by relocation of SVC (Static Var Compensator), which is highly effective for improvement of responsive characteristics for radical voltage fluctuation.