• Journal of Advanced Marine Engineering and Technology
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• v.27 no.7
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• pp.914-920
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• 2003

In this paper, we deal with two drift compensation algorithms of acceleration sensor for measuring the galloping on power transmission line. Firstly, the block diagram of galloping measurement system is given and a galloping model is presented. Secondly, two compensation algorithms, a simple compensation and a period compensation, are proposed. A simple compensation algorithm uses the drifts of velocity and distance at fixed periods, so it is useful for constant drift case. Next, a period compensation algorithm can compensate a periodic drift. This algorithm uses the previous measured data and compensated data for constant period, where the period is obtained by FFT method. Lastly, the effectiveness of proposed algorithms is verified by comparing between two algorithms in simulation, and its characteristics and the drift error bound are shown, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.76-79
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• 2007

Optical compensation films are widely used to enlarge viewing angle characteristics for LCDs. A new surface film with an inner light scattering layer was newly developed to improve gray scale inversion. This paper describes technologies regarding these films that enhance the viewing angle characteristics for LCDs.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.51-58
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• 2006

To compensate for the motion errors in hydrostatic tables, a method to actively control the clearance of a bearing corresponding to the amount of error using actively controlled capillaries is introduced in this paper. The design method for an actively controlled capillary that considers the output rate of a piezo actuator and the amount of error that must be corrected is described. The basic characteristics of such a system were tested, such as the maximum controllable range of the error, micro-step response, and available dynamic bandwidth when the capillary was installed in a hydrostatic table. The tests demonstrated that the maximum controllable range was $2.4\;{\mu}m$, the resolution was 27 nm, and the frequency bandwidth was 5.5 Hz. Simultaneous compensation of the linear and angular motion errors using two actively controlled capillaries was also performed for a hydrostatic table driven by a ballscrew and a DC servomotor. An iterative compensation method was applied to improve the compensation characteristics. Experimental results showed that the linear and angular motion errors were improved to $0.12{\mu}m$ and 0.20 arcsec, which were about $1/15^{th}$ and $1/6^{th}$ of the initial motion errors, respectively. These results confirmed that the proposed compensation method improves the motion accuracy of hydrostatic tables very effectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.761-766
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• 2008

This paper describes a compensation algorithm for a measurement voltage transformer (VT) based on the hysteresis characteristics of the core. The error of the VT is caused by the voltages across the primary and secondary windings. The latter depends on the secondary current whilst the former depends on the primary current, i.e. the sum of the exciting current and the secondary current. The proposed algorithm calculates the voltages across the primary and secondary windings and add them to the measured secondary voltage for compensation. To do this, the primary and secondary currents should be estimated. The secondary current is obtained directly from the secondary voltage and used to calculate the voltage across the secondary winding. For the primary current, in this paper, the exciting current is decomposed into the two currents, i.e. the core-loss current and the magnetizing current. The core-loss current is obtained by dividing the primary induced voltage by the core-loss resistance. The magnetizing current is obtained by inserting the flux into the flux-magnetizing current curve. The calculated voltages across the primary and secondary windings are added to the measured secondary current for compensation. The proposed compensation algorithm improves the error of the VT significantly.

• Journal of Power Electronics
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• v.19 no.2
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• pp.333-343
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• 2019

Dead time and the nonideal characteristics of components all lead to phase voltage distortions. In order to eliminate the harmful effects caused by distortion, numerous methods have been proposed. The efficacy of a method mainly depends on two factors, the compensation voltage amplitude and the phase current polarity. Theoretical derivations and experiments are given to explain that both of these key factors can be deduced from the compensation time, which is defined as the error time between the ideal phase voltage duration and the actual phase voltage duration in one Pulse Width Modulation (PWM) period. Based on this regularity, a novel method for compensating phase voltage has been proposed. A simple circuit is constructed to realize the real-time feedback of the phase voltage. Utilizing the actual phase voltage, the compensation time is calculated online. Then the compensation voltage is derived. Simulation and experimental results show the feasibility and effectivity of the proposed method. They also show that the error voltage is decreased and that the waveform is improved.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.127.6-127
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• 2001

In this paper, we deal with two bias compensation algorithms of acceleration sensor for measuring the galloping on power transmission line. Firstly, the block diagram of galloping measurement system is given and a galloping model is presented. Secondly, two compensation algorithms, a simple compensation and a period compensation, are proposed. A simple compensation algorithm use the drafts of velocity and distance at fixed periods, so it is useful for constant bias case. Next, a period compensation algorithm can compensate a periodic bias. This algorithm use the previous measured data and compensated data for constant period, where the period is obtained by FFT method. Lastly, the effectiveness of proposed algorithms is verified by comparing between two algorithms in simulation, and its characteristics and the bias error bound are shown, respectively.

• Proceedings of the Technology Innovation Conference
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• 2004.06a
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• pp.151-169
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• 2004

Studies on compensation structures of international technology licensing show that the level of intellectual property protection in the host market and the favorableness of the host country's economic environment are positively related to the use of running royalty-based compensation structure. Lump-sum fee or fixed royalty compensation is more likely to be used in the introduction and decline stages of the technology life cycle, and running royalty compensation in the growth stage. The international experience and the size of the licensor company are positively related to the use of running royalty. In this theoretical context, this paper analyzes the compensation structures of technology import in Korea. The paper uses the officially reported data to analyze the compensation structures. It analyzes the characteristics of the compensation structures in terms of fixed royalty and running royalty by licensor country, group of licensor countries and size of licensee companies.

• Journal of Korea Technology Innovation Society
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• v.7 no.3
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• pp.507-531
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• 2004

This study examines the underlying properties of compensation structures and empirically test the difference in a various aspects of the compensation structures of Korean technology imports. In particular, this study looks into the trends of technology licensing from abroad in Korea and analyze the patterns of compensation structures in terms of compensation type, contract period and royalty rate by licensor country, group of licensor countries, size of licensee companies and area of licensed technologies. By doing so, this paper investigates how compensation structures in international technology transactions are determined in Korea and draw implications from the process of discussion.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.688-692
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• 1988

The active filter system for harmonic current compensation is presented in this paper. The active filter, composed of a three-phase voltage-type PWM inverter and the capacitor, compensates both the harmonic currents and the reactive power by injecting the PWM current to the ac line. This paper describes the principle of harmonic current compensation, the calculation circuits for the harmonic currents to be injected, the several compensation characteristics. Also the experimental results are shown to verify the theory proposed in this paper.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1380-1388
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• 2013

The conventional graphical representation of the instantaneous compensation power flow for single-phase active power filters(APFs) simply represents the active power flow and the reactive power flow which flowing between the power source and the active filter / the load. But, this method does not provide the information about the rectification mode and the compensation mode of APFs, especially, the loss for each mode was not considered at all. This is very important to understand the compensation operation characteristics of APFs. Therefore, this paper proposes the graphical representation of the instantaneous compensation power flow for single-phase APFs considering the instantaneous rectification mode and the instantaneous inversion mode. Three cases are verified in this paper - without compensation, with compensation of the active power 'p' and the fundamental reactive power 'q', and with compensation of only the distorted power 'h'. To ensure the validity of the proposed approach, PSIM simulation is achieved. As a result, we could confirm that the proposed approach was easy to explain the instantaneous compensation power flow considering the instantaneous rectification mode and the instantaneous inversion mode of APFs, also, Total Harmonic Distortion(THD)/Power Factor (P.F) and Fast Fourier Transform(FFT) analysis were compared for each case.