• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.10
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• pp.805-810
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• 1989

This paper presents a method for planning reactive power compensation such as shunt capacitors and reacters so as to maintain bus voltage in acceptable range during steady state operation in power system. The algorithm in this paper decomposes the problem into reactive power planning module for the compensation of bus voltage and load flow module for adjusting the error resulted from the linear approximation. A planning technique is based on linear programming to minimize the amount of added reactive power compensation in each case. Transformer tap settings and generator voltages are adjusted to minimize the compensation. The constraints are the operation limits of the control variables and bus voltages. The result of one sample system is presented to confirm the practical use of the proposed algorithm.

• 중국학논총
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• no.61
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• pp.127-153
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• 2019

In this article, I singled out the examples of punishment and compensation seen in Liaozhaizhiyi which is an eighteenth century collection of short stories, and reconstructed the viewpoint of Chinese fortune and misfortune and furthermore presented the cultural meanings that this viewpoint has. The traits of Chinese culture seen in Liaozhaizhiyi are classified as follows: ① Only after carrying on a family line by birth of son(s), a happy conclusion can be made. ② AMain character passes state exam or alternatively his son(s) passes them. ③ Beautiful women / women given as reward have special abilities and talents. ④ Mostly, punishment and Compensation are made on a family basis, not on an individual basis. ⑤ Misfortune derives from a main character's desire; fortune from his sacrifice. ⑥ Norm and criteria for the punishment and compensation are based on confucianism but the procedure of the execution is based on taoism, buddhism, transcendent being and rules of folk religions.

• Journal of Navigation and Port Research
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• v.40 no.2
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• pp.83-87
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• 2016

The maritime industry is expanding at an alarming rate hence there is a perpetual need to improve situation awareness in the maritime environment using new and emerging technology. Tracking is one of the numerous ways of enhancing situation awareness by providing information that may be useful to the operator. The tracking module designed herein comprises determining existing states of high dynamic target warship, state prediction and state compensation due to random noise. This is achieved by first analyzing the process of tracking followed by design of a tracking algorithm that uses ${\alpha}-{\beta}-{\gamma}$ tracking filter under a random noise. The algorithm involves initializing the state parameters which include position, velocity, acceleration and the course. This is then followed by state prediction at each time interval. A weighted difference of the observed and predicted state values at the $n^{th}$ observation is added to the predicted state to obtain the smoothed (filtered) state. This estimation is subsequently employed to determine the predicted state in the next radar scan. The filtering coefficients ${\alpha}$, ${\beta}$ and ${\gamma}$ are determined from a pre-determined value of the damping parameter, ${\xi}$. The smoothed, predicted and the observed positions are used to compute the twice distance root mean square (2drms) error as a measure of the ability of the tracking module to manage the noise to acceptable levels.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.53-54
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• 2015

The maritime industry is expanding at an alarming rate and as such there is a perpetual need to improve situation awareness in the maritime environment using new and emerging technology. Tracking is one of the numerous ways of enhancing situation awareness by providing information that may be useful to the operator. The tracking system described herein comprises determining existing states of own ship, state prediction and state compensation caused by random noise. The purpose of this paper is to analyze the process of tracking and develop a tracking algorithm by using ${\alpha}-{\beta}-{\gamma}$ tracking filter under a random noise or irregular motion for use in a warship. The algorithm involves initializing the input parameters of position, velocity and course. The actual positions are then computed for each time interval. In addition, a weighted difference of the observed and predicted position at the nth observation is added to the predicted position to obtain the smoothed position. This estimation is subsequently employed to determine the predicted position at (n+1). The smoothed values, predicted values and the observed values are used to compute the twice distance root mean square (2drms) error as a measure of accuracy of the tracking module.

• Korean Journal of Social Welfare
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• v.53
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• pp.31-49
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• 2003

Neo-liberalism, the most influential ideology in the current world, argues for the commercialization of social security programs and for the dissolution of the interventionist welfare state. From the neo-liberal viewpoint, social services become more efficient and more advantageous for recipients, when provided by the market, not by the state. It is also argued that the welfare of all social members is best secured when the market freely operates without any interference from the state. From the neo-liberal point of view, an argument was raised to commercialize the state-administered Workers' Compensation program of Korea in the mid-1990s. This argument was faced with strong resistances from labor unions and social welfare circles, and has disappeared since the economic breakdown and the restructuring of Korean society during the late 1990s. Butr, such an argument can emerge anytime as the nee-liberal ideology become more powerful. This article aims to examine the neo-liberal argument that the privatization of social security programs, through an increases in efficiency, improves the interests of the recipients as well as the whole society. For this, this article attempts to analyze the Workers' Compensation programs of the USA, which, from state to state, are administered by the state government or by private insurance companies. This study can serve as an effective critique for the neo-liberal argument, if it finds that state-administered Workers' Compensation programs are more efficient than those managed by insurance companies. This article's another aim is to assess the controversies over the privatization of the Workers' Compensation program of Korea during the mid to late 1990s. The controversies were more about which viewpoint is right and, in most cases, lacked empirical evidence. This study shall empirically criticize the argument for the privatization of the Workers' Compensation program.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.405-415
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• 2016

This paper presents a model predictive control for shunt active power filters in synchronous reference frame using space vector pulse-width modulation (SVPWM). The three phase load currents are transformed into synchronous rotating reference frame in order to reduce the order of the control system. The proposed current controller calculates reference current command for harmonic current components in synchronous frame. The fundamental load current components are transformed into dc components revealing only the harmonics. The predictive current controller will add robustness and fast compensation to generate commands to the SVPWM which minimizes switching frequency while maintaining fast harmonic compensation. By using the model predictive control, the optimal switching state to be applied to the next sampling time is selected. The filter current contains only the harmonic components, which are the reference compensating currents. In this method the supply current will be equal to the fundamental component of load current and a part of the current at fundamental frequency for losses of the inverter. Mathematical analysis and the feasibility of the suggested approach are verified through simulation results under steady state and transient conditions for non-linear load. The effectiveness of the proposed controller is confirmed through experimental validation.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.15-17
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• 2006

This paper proposes a compensation method for an air gapped current transformer (CT) in the steady state. An air gapped CT is used in order to reduce a remanent flux in the case of auto-reclosure. It causes larger ratio and angle errors than the closed core CT because the magnetizing inductance of an air-gapped CT is even smaller than the closed-core CT. The core flux is calculated and used to estimate the exciting current in accordance with the hysteresis curve of the air-gapped CT The correct current is obtained by adding the estimated exciting current to the measured secondary current. The performance of the method was investigated for the air gapped CTs with a gap of 0.083mm and 0.249mm for the 120%, 100% and 20% of the rated current. Various test results indicate that the proposed compensation algorithm can improves the accuracy significantly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.201-206
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• 2004

We have performed computer simulation and experiment to obtain electro-optic characteristics of reflective hybrid aligned nematic (R-HAN) cell driven by fringe field, in which the cell consists of polarizer, optical compensation film, LC layer and reflector. Conventional R-HAN cell driven by fringe field using only the LC layer shows high wavelength dispersion at dark-state and thus viewing angle characteristic is strongly wavelength-dependent. In order to improve this demerit, we added one optical compensation film to conventional R-HAN cell. The display with optimized cell parameters shows low wavelength dispersion at dark-state and exhibits a wide viewing angle without the occurrence of grey scale inversion over a wide range of viewing angles and the contrast ratio greater than 5 over exists about 120$^{\circ}$ in vortical direction and 160$^{\circ}$in horizontal direction. Experimental results show good agreements with theoretical results and fast response time.

• Journal of Power Electronics
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• v.10 no.6
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• pp.769-776
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• 2010

The ultracapacitor module has recently been recast for use in hybrid energy storage systems (HESSs). As a result, accurate state-of-charge (SOC) estimation for an ultracapacitor module is as important as that of primary sources in order to be utilized efficiently in an energy storage system (ESS). However, while SOC estimation via the open-circuit voltage (OCV) method is generally used due to its linear characteristics compared with other ESSs, this method results in many errors in cases of highcurrent charging/discharging within a short time period. Accordingly, this paper introduces a dynamic SOC estimation algorithm that is capable of SOC compensation of an ultracapacitor module even when there is a current input and output. A cycle profile that simulates the operating conditions of a mild-HEV was applied to a vehicle simulator to verify the effectiveness of the proposed algorithm.

• Journal of Power Electronics
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• v.10 no.4
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• pp.419-427
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• 2010

A parallel control strategy in capacity proportion frequency allocation mode for shunt active power filters (APFs) is proposed to overcome some of the difficulties in high power applications. To improve the compensation accuracy and overall system stability, an improved selective harmonic current control based on multiple synchronous rotating reference coordinates is presented in a single APF unit, which approximately implements zero steady-state error compensation. The combined decoupling strategy is proposed and theoretically analyzed to simplify selective harmonic current control. Improved selective harmonic current control forms the basis for multi-APF parallel operation. Therefore, a parallel control strategy is proposed to realize a proper optimization so that the APFs with a larger capacity compensate more harmonic current and the ones with a smaller capacity compensate less harmonic current, which is very practical for accurate harmonic current compensation and stable grid operation in high power applications. This is verified by experimental results. The total harmonic distortion (THD) is reduced from 29% to 2.7% for a typical uncontrolled rectifier load with a resistor and an inductor in a laboratory platform.