• Journal of Institute of Control, Robotics and Systems
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• v.11 no.3
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• pp.207-213
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• 2005

This paper deals with an autonomous flight guidance and control algorithm design for TR301 tilt-rotor airplane under development by Korea Aerospace Research Institute for simulation purpose. The objective of this study is to design autonomous flight algorithm in which the tilt-rotor airplane should follow the given waypoints precisely. The approach to this objective in this study is that, first of all, model-based inversion is applied to the highly nonlinear tilt-rotor dynamics, where the tilt-rotor airplane is assumed to fly at helicopter flight mode(nacelle angle=0 deg), and then the control algorithm, based on classical control, is designed to satisfy overall system stabilization and precise waypoint following performance. Especially, model uncertainties due to the tiltrotor model itself and inversion process are adaptively compensated in a simple neural network(Sigma-Phi NN) for performance robustness. The designed algorithm is evaluated in the tilt-rotor nonlinear airplane in helicopter flight mode to analyze the following performance for given waypoints. The simulation results show that the waypoint following responses for this algorithm are satisfactory, and control input responses are within control limits without saturation.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.12-16
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• 2003

This paper presents a compensation method for a temperature-dependent gain tilt in L-band erbium-doped fiber amplifier using a voltage-controlled attenuator. The gain tilts in the L-band of 1570-1605 nm due to a temperature change have negative slopes, whereas they have positive slopes for the increasing optical input powers in a saturation region. The proposed method utilizes these opposite gain variations to compensate for the gain tilt over a wide range of temperature. While applying forty channels with a channel spacing of 100 GHz in the L-band and changing the ambient temperature from 0 to $50^{\circ}C$, the compensation method maintained the gain deviation within 1 dB.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1661-1667
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• 2013

This paper studies the dynamic irreversible demagnetization characteristics of an interior permanent magnet (PM) brushless DC motor with a stator turn fault. A new algorithm, which is a finite element method (FEM) combined with a line voltage equation of the motor, is developed to analyze irreversible demagnetization under dynamic and transient states and considers a stator turn fault. The input current, circulating current, magnetic distribution characteristics, and operating property of the PM, including the irreversible demagnetization in the fault state, are analyzed using this algorithm by considering the magnetic saturation effect. The feasibility of the proposed method confirmed from the analysis results is verified via an experiment. Through this fault analysis, we can accurately check the fault phenomena of a PM motor against the demagnetization fault for fault prevention.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.19-24
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• 2003

This paper is to research the heat transfer characteristic in copper-water variable conductance heat pipes(VCHP) with a non-condensable gas and gas reservoir. The heat transfer characteristics in the VCHP have not yet been studied much researches. VCHP are used in many applications. These applications range from thermal control of components and systems on satellites, to precise temperature calibration duties, conventional electronics temperature control and thermal diodes. The practical use of VCHP is a simple way to control the temperature of satellites. As the quantity of NCG was increased, there was an increase in the saturation vapor temperatures. As the input heat has loaded from 90 W to 110 W, the difference of the evaporator surface is lower than $10^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.10
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• pp.1066-1074
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• 1990

In this paper, we attempt to control induction motors with high power efficiency as well as high dynamic performance by utilizing the recently developed theories : singular perturbation technique and noninteracting feedback control. Our controller consists of three subcontrollers` a saturation current controller, a decoupling controller, and a well-known flux simulator. The decoupling controller decouples rotor speed (or motor torque) and rotor flux linearly. Our controller does not need the rotor resistance that varies widely with the machine temperature. To illuminate the practical significance of our results, we present simulation and experimental results as well as mathematical performance analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.35-44
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• 2006

When control surface failure occurs, it is conventional to correct a current control or to transform to other control. In this paper, instead of adopting a conventional way, a reconfiguration method which compensate the failure with alternative control surface deflection, depending on the level of failure, by using neural network and PCH(Pseudo-Control Hedging). The Conroller is designed of inner-loop(SCAS : Stability Command Augmentation System) with DMI(Dynamic Model Inversion) and outer-loop with Y axis acceleration feedback for a coordinate turn. Additionally, double PCH method was adopted to prevent actuator saturation and input command was generated to compensate for failure. At the end, The feasibility of the method is validated with randomly selected failure scenarios.

• Journal of Magnetics
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• v.18 no.4
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• pp.428-431
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• 2013

We demonstrate that a partial loading of $Ni_{0.5}Zn_{0.5}Fe_2O_4$ (Ni-Zn ferrite) film remarkably improves impedance matching of electrically small $Ba_3Co_2Fe_{24}O_{41}$ ($Co_2Z$) hexaferrite antenna. A 3 ${\mu}m$ thick Ni-Zn ferrite film was deposited on a silicon wafer by the electrophoresis deposition process and post-annealed at $400^{\circ}C$. The fabricated Ni-Zn ferrite film has saturation magnetization of $268emu/cm^3$ and coercivity of 89 Oe. A partial loading of the Ni-Zn ferrite film on the $Co_2Z$ hexaferrite helical antenna increases antenna return loss to 24.7 dB from 9.0 dB of the $Co_2Z$ antenna. Experimental results show that impedance matching and maximum input power transmission to the antenna without additional matching elements can be realized, while keeping almost the same size as the $Co_2Z$ antenna size.

• Journal of the Korean Graphic Arts Communication Society
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• v.28 no.2
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• pp.117-128
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• 2010

Advancements in digital image have put high quality digital camera into the hands of many image professionals and consumers alike. High quality digital camera images consist originally of raw which have a set of color rendering operation applied to them to produce good images. With color rendering, the raw file was converted to Adobe RGB and sRGB color space. Also color rendering can incorporate factor such as white balance, contrast, saturation. Therefore, in this paper we conduct a study on production of optimum profile considered color rendering in digital camera. To do the experiment, the images were Digital ColorChecker SG target and ColorChecker DC target. A profiling tool was ProfileMaker 5.03. The results were analyzed by comparing in color gamut of $CIEL^*a^*b^*$ color space and calculating ${\Delta}E^*_{ab}$. Also results were analyzed in terms of different $CIEL^*a^*b^*$ color space quadrants based on lightness, chroma.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.269-280
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• 2020

This research aims to determine the direct and indirect effects of digital literacy, economic literacy, and entrepreneurial skills on the performance of small- and medium-sized enterprises (SMEs) in garment clusters in the Bulak tourism industry Depok. Carrying out quantitative research with survey methods, data collection is using a questionnaire technique with 90 respondents, via saturation sampling. This research data analysis uses SPSS software version 25.0. Path analysis is used to determine the direct and indirect effects between variables. The results showed digital literacy, economic literacy, and entrepreneurial skills significantly and positively affect the performance of small- and medium-sized enterprises. The main finding in this study is that digital literacy has the greatest influence on the performance of SME entrepreneurs, both directly and indirectly. The results of the study provide input on performance development strategies for SME entrepreneurs through digital literacy, including digital business relationships, online facilities, and networks. The findings are also complementary to the factors shaping the performance of SME entrepreneurs in the digital age. The research results show that digital literacy has the greatest direct and indirect influence on the performance of SME entrepreneurs; this shows the essential contribution of digital literacy in developing business and marketing networks.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.3
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• pp.110-115
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• 2002

This paper proposes the adaptive fuzzy control system using the microprocessesor for high precision control of automation systems which exist non-linearities such as saturation, relays, hysteresis, and dead zones. The proposed system which provides the improvement in terms of the control region in transient and adaptive control, first used the frequence-locked mothed driving a system to generate a output voltage proportional to the frequency diffierence of relnence input signal and feedback signal for fast transient response,, and when the error reaches the preset value, used the adaptive fuzzy logic for precision control. The theoretical and experimental studies have been carried out. The presented results from the above investigation show considerable improved performance in the precision control of servo control systems.