• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.229-231
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• 2005

This paper presents the nonlinear $H_{\infty}$ switching power system stabilizer (PSS) based on Lie group and Lie transformation theory. The proposed controller combines the $H_{\infty}$ switching controller and Lie theory. The proposed power system stabilizer (PSS) is used to improve the transient stability in the time-domain and to solve the problem associated with the inaccessible state variables by measuring only the angular velocity. In the simulation study, the different load conditions, fault periods, and fault locations are considered. The nonlinear time-domain simulation showed that the proposed controller was effective restoring transient stability in a one-machine infinite-bus power system.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1527-1530
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• 1996

Telerobot system is being developed for the application to nuclear power plants by Korea Atomic Energy Research Institute. Human-machine interaction and interface are very important elements of telerobotic systems. The main purpose of this study is developing a control system based on 3-D graphic techniques for the easy user interface and realistic visual I information supply. This system possesses the abilities for (1) virtual work, environment modelling and simulation, (2) kinematic animation include redundant behavior (3) interfacing with a real robot system, (4) transformation between real and virtual mode within the same graphics system. This system is especially focused on enhancing the overall efficiency and reliably of nozzle dam installation task inside water chamber of steam generator in nuclear power plant.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1119-1125
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• 1999

In this paper, a decentralized multilevel-adaptive controller for a boiler-turbine system is designed by using multiple model adaptive method. It is applied to the drum type boiler-turbine system which is simplified from Boryung T/P #1,2 model. A linearlized model is decomposed into three subsystems by means of linear transformation. Then the DMC based on such subsystem is designed and a Multiple Model Adaptive Control(MMAC) scheme is applied for the purpose of the good tracking to variable load demands of the thermal power plant. The good performance of the designed controller is shown by simulations in various conditions that have the large step and ramp change of power demamd.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.173-177
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• 2013

This paper presents a new method for analyzing the maximum efficiency of a wireless power transfer (WPT) system with multiple n resonators. The method is based on ABCD matrices and allows transformation of the WPT system with multiple n resonators into a single two-port network system. The general maximum efficiency equation of a WPT system with multiple n resonators is derived using the ABCD matrix. Use of this equation allows placement of the relay resonators for maximum efficiency even though they are asymmetrical. The general maximum efficiency equation and the method of the optimum placement are verified by a full wave simulation. The results show that the method is useful for the analysis of a WPT system with relay resonators.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1371-1376
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• 1990

The paper presents a method of constructing simple fuzzy control rules for the determination of stabilizing signals of automatic voltage regulator and governor, which are controllers of electric power systems. Fuzzy control rules are simplified by considering a coordinate transformation with the rotation angle .theta. on the phase plane, and by expanding the range of membership functions. Also, two rotation angles .theta. $_{1}$ and .theta. $_{2}$ are selected for the linearizable region and the nonlinear one of the system, respectively. Here, .theta. $_{1}$ is chosen by the pole assignment method, and .theta. $_{2}$ by a performance index. Fuzzy inference is applied to the connection of two rotation angles .theta. $_{1}$ and .theta. $_{1}$ by regarding the distance from the desired equilibrium point as a variable of condition parts. The control effect is demonstrated by an application of the proposed method to one-machine infinite-bus power system.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.78-79
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• 1998

This paper describes a real time algorithm for blood flow estimation of LDF(laser Doppler flowmeter). Many algorithms for blood flow estimation are using power spectral density of Doppler signal by blood flow. In these research, the fast Fourier transformation is used to estimate power spectral density. This is a block processing procedure rather than real time processing. The algorithm in this paper used parametric spectral estimation. This has real time capability by estimation of AR(autoregressive) parameters sample by sample, and has smoothing power spectrum. Also, the frequency resolution is not limited by number of samples used to estimate AR parameter. Another advantage of this algorithm is that AR model enhance SNR.

• Journal of Korean Physical Therapy Science
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• v.10 no.1
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• pp.83-89
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• 2003

An electromyogram (EMG) using surface electrodes is one of the indirect tests most frequently used to ascertain muscle fatigue. An EMG can be used in two ways. The first technique determines the root mean square (RMS), which reflects the amplitude of the EMG signal. The second technique determines the median and mean power frequencies through EMG power spectrum analysis. The purpose of this article is for determine the correlation between work and percent root mean square(%RMS) and between work and MDF of EMG based on muscle contractions. It is used the %RMS, which reflects the amplitude of the EMG signal For MDF, it is used the frequency power spectrum analysis method, which involves the fast Fourier transformation (FFT) of the original Signals.

• Management Science and Financial Engineering
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• v.18 no.2
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• pp.23-27
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• 2012

The problem of jointly determining a robust optimal bundle of price and order quantity for a retailer in a single-retailer, single supplier, single-product supply chain is considered. Demand is modeled as a decreasing power function of product price, and unit purchasing cost is modeled as a decreasing power function of order quantity and demand. Parameters defining the two power functions are uncertain but their possible values are characterized by ellipsoids. We extend a previous study in two ways; the purchasing cost function is generalized to take into account the economies of scale realized by higher product demand in addition to larger order quantity, and an exact transformation into an equivalent convex optimization program is developed instead of a geometric programming approximation scheme proposed in the previous study.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.333-338
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• 2014

This paper concerns the development of the transformer that can reduce harmonics supplied to the system if the output of photovoltaic inverter in the photovoltaic system is grid-connected, and suggests that problems of harmonics and power factor degradation in the grid-connected photovoltaic system can be improved. In this study, the burden of increasing the investment in new facilities and securing their installation space due to harmonics has been substantially eased through the development of a hybrid transformer possessing unbalanced function and harmonics reduction function using zig-zag coils, and most of all, it is expected that the development of such high efficiency hybrid transformer possessing functions of transformation and reducing harmonics can improve the power quality as well as prevent damages caused by harmonics, leading to suppress unnecessary loss of electric power and thereby contribute to energy savings.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.86-88
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• 2007

In solar power system, the height and azimuth of the sun are important parameters which control generated power magnitude. The tracking method that controls the daily generation magnitude according to latitude and longitude using the two axles is often used in the existing sunlight tracking system today. In this two-axle PV track control system, the self-load is concentrated on one FRAME. It is influenced of the regular load, snow load and the wind load, etc. It is difficult to set up the system in the conventional building. This research is a development about the small-scale economy track device of independent load-dispersing solar generation system. The position tracking algorithm is through the new coordinates transformation calculating the height and azimuth of the sun.