• Journal of The Korean Astronomical Society
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• v.33 no.2
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• pp.123-126
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• 2000

We have developed a near real-time flare alerting system which (1) downloads the latest GOES-l0 1-8 ${\AA}$ X-ray flux 1-min data by an automated ftp program and shell scripts, (2) produces a beep sound in a simple IDL widget program when the flux is larger than a critical value, and (3) makes it possible to do a wireless alerting by a set of portable transceivers. Thanks to the system, we have made successful Ha flare observations by the Solar Flare Telescope in Bohyunsan Optical Astronomy Observatory. This system is expected to be helpful for ground-based flare observers.

• Publications of The Korean Astronomical Society
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• v.11 no.1
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• pp.147-161
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• 1996

The development of universal CCD camera control software for all BOAO CCD camera systems is proposed. The new software, running under Sun SPARCstation and motif based X window system with SunOS 4.1.3 operating system, replaces existing control software based on NeXTstation color and NeXTstep 2.1 operating system which is no more produced now. Several new features of the new software is introduced, some of which are 1) the image contrast is enhanced by color manipulation and display, 2) image zooming and trimming, 3) any size of image can be displayed in the scrolled window, and 4) the offset between telescope pointing position and CCD center is easily calculated by alt-azi map. Along with the above new features, the new software has advantages including ease of maintenance and upgrading and elimination of risk caused by hardware damage. Since September 1, the software beta version is being used by observers and there is not seen severe problem regarding the software itself, but several requests to equip more features to the software will be mirrored to future release.

• Journal of Families and Better Life
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• v.20 no.1
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• pp.115-124
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• 2002

The purpose of this study is to examine the social competence of children with reference to day care center's structural, process variables and demographic variables. The subjects were 156 children who attend day care center, aged from 3 to 5 years and 9 teachers in Seoul or the province of KyungkiDo. Data were gathered via the structured Questionnaires distributed to the teachers to rate children's social competence and their own job satisfaction. And two observers rated teacher-child interaction in day care center The major findings are as follows The variables predicting children's social competence were child's sex, age, period of attendance in day care center, teacher's job satisfaction, and group size. Especially this study suggests that teachers who are highly satisfied with their job and small group size influence children's social competence positively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.191-192
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• 2011

The construction projects contain a lot of variables and risk affecting productivity. The duration of the project must be recognized important as for quality, unit cost and safety. There is need for improving work efficiency by investigating relationship of works to prevent delay. This study focuses on analysing the delay factors of steel staircase system to suggest regression model that enables construction productivity estimation. The position of the observers and construction delay factors were expressed by the independent variable of the regression model and productivity was expressed by a dependent variable. This paper suggests quantitative productivity and it is expected that will be helpful estimating application in construction new technologies.

• Information Display
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• v.15 no.5
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• pp.22-32
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• 2014

The current research intends to quantify the surround luminance effects on the shape of spatial luminance CSF and to propose an image quality evaluation method that is adaptive to both surround luminance and spatial frequency of a given stimulus. The proposed image quality method extends to a model called SQRI[8]. The non-linear behaviour of the HVS was taken into account by using CSF. This model can be defined as the square root integration of multiplication between display MTF and CSF. It is assumed that image quality can be determined by considering the MTF of the imaging system and the CSF of human observers. The CSF term in the original SQRI model was replaced by the surround adaptive CSF quantified in this study and it is divided by the Fourier transform of a given stimulus. A few limitations of the current work should be addressed and revised in the future study. First, more accurate model predictions can be achievable when the actual display MTF is measured and used instead of the approximation. Then, a further improvement to the model prediction accuracy can be made when chromatic adaptation of the HVS is taken into account[45-46].

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.67-72
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• 2001

In this study, a methodology of synchronous control which can be applied to position synchronization of a two-axes driving system has been developed. The synchronous error is caused by model uncertainties and torque disturbance of each axis. To overcome these problems, the proposed synchronous control system has been composed of two speed controllers, disturbance observers, and one synchronous controller. The speed controllers, based on the PID control law are aimed at the following to speed reference. And the parameters of speed controllers have been designed in order for the speed response fo the second axis to correspond with the one of the first axis. The disturbance observer has been designed to restrain the torque disturbance. The synchronous controller eliminates the synchronous error by controlling the speed of the second axis. The effectiveness of the proposed method has been verified through simulation.

• International Journal of Ocean System Engineering
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• v.1 no.1
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• pp.16-27
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• 2011

The depth and heading control of an autonomous underwater vehicle (AUV) are considered to follow the predetermined depth and heading angle. The proposed control algorithm was based on a sliding mode control, using estimated hydrodynamic coefficients. The hydrodynamic coefficients were estimated employing conventional nonlinear observer techniques, such as sliding mode observer and extended Kalman filter. Using the estimated coefficients, a sliding mode controller was constructed for a combined diving and steering maneuver. The simulated results of the proposed control system were compared with those of a control system that employed true coefficients. This paper demonstrated the proposed control system, and discusses the mechanisms that make the system stable and accurately follow the desired depth and heading angle in the presence of parameter uncertainty.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.891-897
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• 2012

In this paper, the observer based nonlinear state feedback controller has been developed to control the pressures of the oxygen and the hydrogen in the PEM(Proton Exchange Membrane) fuel cell system. Nonlinear model of the PEM fuel cell system was introduced to study the design problems of the state observer and model based controller. A cascade observer using the filtering technique was used to estimate the pressure derivatives of the cathode and the anode in the system. In order to estimate the pressures of the cathode and the anode, the sliding mode observer was designed by using these pressure derivatives. To estimate the oxygen pressure and the hydrogen pressure in the system, the nonlinear state observer was designed by using the cathode pressure estimates and the anode it. These results will be very useful to design the state feedback controller. The validity of the proposed observers and the controller has been investigated by using the Lyapunov's stability analysis strategy.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1995.11a
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• pp.184-192
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• 1995

Although ship's draught information onboard is substantial for both the safety of navigation and the estimation of loaded cargoes its accuracy depends in traditional surveying method on the skillfulness of observers and the condition of the sea surface round the vessel. To obtain more accurate information accessibly measuring instruments with sophisticated sensors such as mechanical electronic and ultrasonic transducers have been developed. however they have still limitation in accuracy and in making up a system due to the complexity of processing signal. In this paper we propose a he technique for analyzing ultrasonic pulse signal in order to improve the measurement accuracy and simplify a remote sensing system of draught by ultrasonic waves. This technique is useful for measuring draught being considered the influence of sea surface fluctuation and for transferring its data briefly to required equipment in integrated bridge system.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.3
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• pp.145-153
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• 2004

A nonlinear adaptive speed observer is designed for the sensorless control of induction motors. In order to design the speed observer, the measurements of the stator currents and the estimates of the rotor fluxes are used. The sliding mode cascade observer is designed to estimate the time derivatives of the stator currents. The open-loop observer is designed to estimate the rotor fluxes and its time derivatives using the stator current derivatives. The adaptive observer is also designed to estimate the rotor resistance. Sequentially, the rotor speed is calculated using these estimated values. It is shown that the estimation errors of the corresponding states and the parameters converge to the specified residual set. It is also shown that the speed controller using these estimates is performed well. The simulation examples are represented to investigate the validity of the proposed observers for the sensorless control of induction motors.