• Journal of Information Display
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• v.8 no.1
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• pp.26-31
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• 2007

This paper presents ergonomic approaches to editing and evaluating content for 3D displays. Two systems, a nonlinear editing system and an evaluation system, were developed to improve viewing safety and comfort for 3D content observers and provide better usability for the creators from the viewpoint of ergonomics.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.921-925
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• 1988

An attractive approach to speed of induction motors is to achieve full linearization via appropriate feedback. However, the prior results toward this direction are based on full feedback. In practice, rotor fluxes are not directly measurable but can be estimated using observers. We propose a nonlinear feedback controller with an observer. As t${\rightarrow}{\infty}$, the closed-loop system with our controller becomes as if it were a linearly decoupled system. We provide the stability analysis of our control method. Simulation and experimental results are also included to demonstrate the practical significance of our results.

• Korean Journal of Child Studies
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• v.18 no.1
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• pp.5-21
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• 1997

This study compared children's daily activities In the preschools of middle-and lower-income communities. 22 children, evenly divided by community and children's gender, were observed for 3 hours on 5 consecutive days. The observers followed the target child, gathering data during 30-second "windows" every 4 1/2 minutes. A total of 750 observations were used in the analyses. The findings show the variation in children's activities as a function of community differences. In the case of academic activities, children of middle-income community were more exposed to and engaged in play with academic objects more than children of the of low-income community. A reverse tendency, however, was found in academic lessons. Children of low-income community were more exposed to work than their counterparts. Children of middle-income community were engaged in child-adult conversation more than those of low-income community. In addition, children of the middle-income community initiated their involvement in play and conversation more than their counterparts, though no difference was found in children's initiation of activities.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.851-857
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• 2019

A new robust sliding mode control with disturbance and state observers has been proposed to control the nozzle angle of a water-jet system for a Unmanned Surface Vehicle (USV). As the water-jet system of a ship is subjected to direct disturbances owing to the exposure to the marine environment in water, it requires a robust control. A state observer and a disturbance observer are added to the water jet nozzle control system to achieve a robust control against disturbances. To verify the performance of the proposed algorithm, a test bed is constructed by a propulsion system used in the popular USV. This proposed algorithm has been evaluated by comparing to the existing algorithm through experiments. The results show that the performance of the proposed algorithm is better than that of the conventional PID or sliding mode controller when controlling the steering of the USV with disturbances.

• Journal of the Korea Society of Computer and Information
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• v.5 no.2
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• pp.152-157
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• 2000

Today, Korea's internet observers are saying that one of the biggest things holding back the explosive growth of online sales is, more than ever before. One of the biggest problem in Electronic Commerce is that the companies which are not oriented clearly fall behind. Electronic Commerce is changing the world. The company should concentrate on where to go in New economy(Digital economy) Therefore. I'd like to study the successful strategy for Electronic Commerce to give management levels right decisions.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1998.11a
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• pp.53-60
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• 1998

In this study, smoke filling behaviors in a large space were investigated. For experimental study, thermocouples were used to measure the temperature of the hot gases layer and also to determine the smoke layer depth. Height markers were also hung from the roof so that observers could visibly assess the smoke layer depth. Ethanol was used as fuel. The smoke filling times were predicted with zone model and field model and numerical results were compared with experimental data. Good results were obtained.

• Journal of Astronomy and Space Sciences
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• v.29 no.2
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• pp.209-220
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• 2012

This paper will introduce and overview in general the $Seongbyeon$ $Deungrok$ issued by the Gwansang-gam, the Astronomical Board in the Joseon Dynasty of Korea. All the Chinese characters in the 1668 $Seongbyeon$ $Deungrok$ was deciphered at first and these were translated into Korean and English. With these translations and the word 'white vapor' in particular we discuss the nature of the main object in this $Deungrok$. Lastly, names of observers who engaged in the observations of this 1668 celestial, which are made as a by-product of this research, are introduced.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.193-198
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• 1984

This study was conducted to compare the chip removal capability of root canal enlarging instruments. Fifty five buccal or mesial canals from upper and lower molar teeth were randomly selected and divided into three groups; Reamer, K-type file and K-flex file. Fifteen canals in each group were individually enlarged with one of three tested instruments and irrigated with 5cc of normal saline solution. After instrumentation, each canal was dried with paper point and the canal was splited longitudinally and the cleanness of root canal surface was evaluated under stereoscope by three observers. The results were as follows; 1. Most of the canals experimented showed varying degree of the presence of debris. 2. The canals prepared with reamers showed the most clean canal surface. 3. There was no significant difference in debridement effect between k-type file and k-flexfile.

• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.435-449
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• 2004

In this paper, a novel anti-sway control system that uses an inclinometer as a sway sensor is investigated. The inclinometer, when compared with a vision system, is very cheap, durable, and easy to maintain, while providing almost the same performance. A number of observers to estimate the angular velocity of the load and the trolley velocity are presented. A state feedback controller with an integrator is designed. After a time-scale analysis, a 1/4-size pilot crane of a rail-mounted quayside crane was constructed. The performance of the proposed control system was verified with a real rubber-tired gantry crane at a container terminal as well as with the constructed pilot crane. Experimental results are provided.

• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.530-535
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• 2004

This paper deals with the unknown input observer (UIO) design problem for a class of linear time-delay systems. A case in which the observer error can completely be decoupled from an unknown input is treated. Necessary and sufficient conditions for the existences of such observers are present. Based on Lyapunov stability theory, thedesign of the observer with internal delay is formulated in terms of linear matrix inequalities (LMI). The design of the observer without internal delay is turned into a stabilization problem in linear systems. Two design algorithms of UIO are proposed. The effect of the proposed approach is illustrated by two numerical examples.