• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.106-109
• /
• 2003

This paper describes an AC voltage regulator using AC chopper and auxiliary transformer which is series connected with main input. It has many advantages such as fast voltage control, high efficiency and low THD. A detail study of step down AC voltage regulator is described and two kinds of novel step-up/down voltage regulator for AVR are proposed. The operation principle and PWM method of the proposed regulator are described. Experimental results show that it can be used as AC voltage regulator for special purpose very efficiently.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.493-496
• /
• 1997

This paper constructed the experimental system which is able to drive in series or separately excited by switching of the field winding, using a DC motor and obtained the characteristics of efficiency with speed and torque of each motor's type through the experiment. From this result controlled drive which is able to series DCM or separately excited DCM in the optimal point of efficiency as finding the types of motor having maximum efficiency with torque and speed. By performing high efficiency tracking drive, it is expected that energy consumption of power source with limited energy density would be reduced, and so utility efficiency would be improved.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.6
• /
• pp.1089-1094
• /
• 2016

In order to establish the robust controller design technique of series wound motor driver system. This paper proposes a method of Bang-Bang controller using a series wound motor driver system under improperly variable load. A Bang-Bang controller structure is simpler than the structure of PID plus Bang-Bang controller. This paper shows that a general 8 bits microprocessor is used efficiently implementing such an algorithm. The calculation time of software is extremely small when compared with conventional PID plus Bang-Bang controller. Both nonlinear operating characteristics of digital switching elements and describing function methods are used for the analysis and synthesis. Real time implementation of Bang-Bang controller is achieved. Concept design strategy of the control and PWM waveform generation algorithms are presented in the paper.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.205-208
• /
• 2002

The single phase induction motor(SPIM) with two windings, main and auxiliary winding, is widely used due to ruggedness, low maintenance and simplicity of construction. There are several ways of starting single phase induction motor. The most common method is to use centrifugal switch that is connected in series with a capacitor. But the centrifugal switch that is the external starting system has many problems. In this paper, we use triac to overcome defects that happen by centrifugal switch, Also we used inductor that connected with main winding to get a gate trigger voltage signal. Experiments are focused on a capacitor starling single phase induction motor.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.10
• /
• pp.116-126
• /
• 2001

This paper suggests a numerical method to find optimal geometric path and minimum-time motion for a spatial 6-link manipulator arm (PUMA 560 type). To find a minimum-time motion, the optimal geometric paths minimizing 2 different dynamic performance indices are searched first, and the minimum-time motions are searched on these optimal paths. In the algorithm to find optimal geometric paths, the objective functions (performance indices) are selected to minimize joint velocities, actuator forces or the combinations of them as well as to avoid one static obstacle. In the minimum-time algorithm the traveling time is expressed by the power series including 21 terms. The coefficients of the series are obtained using nonlinear programming to minimize the total traveling time subject to the constraints of velocity-dependent actuator forces.

• Proceedings of the KIEE Conference
• /
• 1987.11a
• /
• pp.530-533
• /
• 1987

In high-frequency switched mode converters, Series Resonant Converter (SRC) is investigated using state-plane method. Phase plane trajectories of the SRC permit a direct closed form solution of the steady state operation and can make problems easy to solve. This paper describes steady state responses and characteristics of the SRC with respect to various circuit factors. The magnitute of steady state response and the average current through load are clearly related to how such the switching frequency differs from the resonant frequency. The results of the steady state analysis can be used to estimate the device and component stress on the power circuit.

• KIEE International Transactions on Power Engineering
• /
• v.4A no.3
• /
• pp.159-166
• /
• 2004

Forecasting prices in electricity markets is critical for consumers and producers in planning their operations and managing their price risk. We utilize the generalized autoregressive conditionally heteroskedastic (GARCH) method to forecast the electricity prices in two regions of New York： New York City and Central New York State. We contrast the one-day forecasts of the GARCH against techniques such as dynamic regression, transfer function models, and exponential smoothing. We also examine the effect on our forecasting of omitting some of the extreme values in the electricity prices. We show that accounting for the extreme values and the heteroskedactic variance in the electricity price time-series can significantly improve the accuracy of the forecasting. Additionally, we document the higher volatility in New York City electricity prices. Differences in volatility between regions are important in the pricing of electricity options and for analyzing market performance.

• Wind and Structures
• /
• v.2 no.2
• /
• pp.85-94
• /
• 1999

The EARPG(1)/UPS was first developed by Seong (1993) and has been tested for wind pressure time series simulations (Seong and Peterka 1993, 1997, 1998) to prove its excellent performance for generating non-Gaussian time series, in particular, with large amplitude sharp peaks. This paper presents a parametric study focused on simulation of extreme value statistics based on the synthetic realizations of the EARPG(1)/UPS. The method is shown to have a great capability to simulate a wide range of non-Gaussian statistic values and extreme value statistics with exact target sample power spectrum. The variation of skewed long tail in PDF and extreme value distribution are illustrated as function of relevant parameters.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.3
• /
• pp.544-551
• /
• 2011

This paper presents the circuit arrangement and effective control method of regenerative energy storage system for an electric vehicle using super-capacitors as the braking energy storage element. A bi-directional controlled current flow of the DC-DC converters with the capacitor bank is connected in parallel with battery, and is controlled so that the whole of the braking energy is effectively absorbed into the capacitors and released back to the electric motor upon acceleration. The converter needs the series-parallel switching circuit for making the best use of the series capacitors and for limiting the step-up ratio of the boost converter. The proposed methods are verified by computer simulation and experimental set-up. They are usefully applied to the electric vehicles such as green cars, electric motorcycles, bike, etc which are power- supplied by the electric batteries.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.1
• /
• pp.115-126
• /
• 2023

Due to the fluctuating random and periodical nature of renewable energy generation power quality disturbances occurred more frequently in power generation transformation transmission and distribution. Various power quality disturbances may lead to equipment damage or even power outages. Therefore it is essential to detect and classify different power quality disturbances in real time automatically. The traditional PQD identification method consists of three steps: feature extraction feature selection and classification. However, the handcrafted features are imprecise in the feature selection stage, resulting in low classification accuracy. This paper proposes a deep neural architecture based on Convolution Neural Network and Long Short Term Memory combining the time and frequency domain features to recognize 16 types of Power Quality signals. The frequency-domain data were obtained from the Fast Fourier Transform which could efficiently extract the frequency-domain features. The performance in synthetic data and real 6kV power system data indicate that our proposed method generalizes well compared with other deep learning methods.