• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1195-1198
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• 1999

This paper presents optimal placement of minimal set of phasor measurement units(PMU's) and observability of measurement system with PMU. By using the incidence matrix symbolic method which directly assigns measurement and pseudo-measurement to incidence matrix, it is much simpler and easier to analyze observability. The optimal PMU set is found through the simulated-annealing(SA) and the direct combinational method. The cooling schedule parameter which is suitable to the property of problem to solve is specified and optimal placement is proven by presented direct combinational method. Search spaces are limited within reasonable feasible solution region to reduce a unnecessary one in the SA implementation based on global search. The proposed method presents to save CPU time and estimate state vectors based on optimal PMU set.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.950-960
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• 2010

In this paper, a multi-input multi-output(MIMO) integral variable structure system with an integral-augmented sliding surface is designed for the improved robust control of uncertain multivariable system under the matched persistent disturbance. To effectively remove the reaching phase problems, the integral augmented sliding surface is proposed. Then for its design, the eigenstructure assignment technique is introduced to. To guarantee the designed performance against the persistent disturbance, the stabilizing control for multi-input system is also designed to generate the sliding mode on the integral sliding surface. The stability of the global system together with the existence condition of the sliding mode are investigated and proved for the case of multi input system in the presence of uncertainty and disturbance. The reaching phase is completely removed in proposed MIMO VSS by satisfying the two requirements. An example and computer simulations will be present for showing the usefulness of algorithm.

• Journal of the Korean earth science society
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• v.27 no.7
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• pp.705-714
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• 2006

The purpose of this study was to explore the elementary students' perceptions of Earth systems and environmental issues. A survey was conducted to determine the students' perceptions on the following aveas: (1) the concepts of certainty and tangibility, (2) self-reported knowledge level, (3) perceived danger level of selected eight Earth systems and environmental issues, and (4) their primary information source on these issues. Results indicated that ozone hole, acid rain, El $Ni\widetilde{n}o$, and global warming were identified by the students as uncertain and intangible issues. Perceived certainty and perceived tangibility were highly positively correlated with self-reported knowledge compared to other relationships. The results also showed that learning from school was the most frequent information source for environmental issues. The second most frequently used source of information was television among several mass media sources. It is hoped that this study contributes to understanding the elementary school students' perceptions toward the selected Earth systems and environmental issues.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.109.1-109
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• 2001

This paper deals with the path following problem of car-like intelligent mobile robot. A robust sliding mode control law based on time-varying state feedback is performed via Lyapunov method for path tracking of nonholonomic mobile robot with uncertainties. At first, A sliding control law is designed by combing the natural algebraic structure of the chained form system with ideas from sliding mode theory. Then, a robust control law is proposed to impose robustness against bounded uncertainties in path tracking. The problem of estimating the asymptotic stability region and the sliding domain of uncertain sliding mode system with bounded control input is also discussed. The proposed sliding mode control law can ensure the global reaching condition of the uncertain control system.

• Journal of applied mathematics & informatics
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• v.5 no.3
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• pp.597-606
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• 1998

In the present study we consider a mathematical model of a non-interactive type autotroph-herbivore system in which the amount of autotroph biomass consumed by the herbivore is assumed to follow a Holling type II functional response. We have also incorpo-rated discrete time delays in the numerical response term to represent a delay due to gestation and in the recycling term which represent a delay due to gestation and in the recycling term which represents the time required for bacterial decomposition. We have derived con-dition for global asymptotic stability of the model in the absence of delays. Conditions for delay-induced asymptotic stability of the steady state are also derived. The length of the delay preserving stability has been estimated and interpreted ecologically.

• Journal of Power System Engineering
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• v.14 no.4
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• pp.23-28
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• 2010

Of the roughly four million known substances, about 60,000 are processed and sold ; many of these must be dried. Many materials are processed in the liquid state - ideal for mixing and reacting - but most products are needed or wanted as dry, or relatively dry, solids. Usually operation is just below atmospheric pressure, as with direct dryers, but some are built for vacuum operation with pressures as low as 26.66kPa abs.. In spite of the global-class aquiculture agriculture and fisheries technology of our country, the processing technologies are lags behind the other nations relatively. These problems are considered to be caused directly by the lack of drying technologies. This paper is concerned to the experimental results of drying heat transfer characteristics for the green energy type vacuum dryer for the high quality agriculture and fisheries production.

• The Korean Journal of Food And Nutrition
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• v.24 no.3
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• pp.329-339
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• 2011

The purpose of this study was to compare the effects of service failure magnitude on perceived justice, positive emotion, and revisit intention at restaurants between a collectivist culture(Korea) and an individualistic culture(United States). The results showed that the higher a customer's perception of service failure magnitude, the lower the perceived recovery justices in both cultures. The distributive, procedural, and interactional justices had a favorable effect on positive emotions in both cultures. Other findings revealed that interactional justice was the best predictor of revisit intention in Korea, while distributive justice was the best determinant of revisit intention in the United States. This research suggests that global restaurant managers need to understand how cultural orientation influences consumer perceptions of service failures in order to develop a highly targeted and effective service recovery.

• Journal of Auto-vehicle Safety Association
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• v.10 no.1
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• pp.38-44
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• 2018

This paper presents an analysis on driving safety in lane change situation based on road driving data. Autonomous driving is a global trend in vehicle industry. LKAS technologies are already applied in commercial vehicle and researches about lane change maneuver have been actively studied. In autonomous vehicle, not only safety control issue but also imitating human driving maneuver is important. Driving data analysis in lane change situation has been usually dealt with ego vehicle information such as longitudinal acceleration, yaw rate, and steering angle. For this reason, developing safety index according to surrounding vehicle information based on human driving data is needed. In this research, driving data is collected from perception module using LIDAR, radar and RT-GPS sensors. By analyzing human driving pattern in lane change maneuver, safety index that considers both ego vehicle and surrounding vehicle state by using relative velocity and longitudinal clearance has been designed.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.66.1-66.1
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• 2010

Using two-dimensional numerical hydrodynamic simulations, we investigate the star formation rate (SFR) in turbulent, multiphase, galactic gaseous disks. Our simulation domain is axisymmetric, and local in the radial direction and global in the vertical direction. Our models include galactic rotation, vertical density stratification, self-gravity, radiative heating and cooling, and thermal conduction, but do not include spiral-arm features. Turbulence in our models is driven by momentum feedback from supernova explosion events occurring in localized dense regions formed by thermal and gravitational instabilities. Self-consistent radiative heating, representing enhanced/reduced FUV photons from the star formation, is also taken into account. By controlling three parameters (the gas surface density, the stellar disk density, and the angular rotation rate) that characterize local galactic disks, we explore how the SFR depends on the background environmental state. We also discuss the relation between the SFR and the gas surface density found in our numerical models in comparison with observations.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.74.1-74.1
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• 2010

Using two-dimensional numerical hydrodynamic simulations, we investigate the regulation of star ormation rates in turbulent, multiphase, galactic gaseous disks. Our simulation domain is xisymmetric, and local in the radial direction and global in the vertical direction. Our models nclude galactic rotation, vertical stratification, self-gravity, heating and cooling, and thermal onduction. Turbulence in our models is driven by momentum feedback from supernova events ccurring in localized dense regions formed by thermal and gravitational instabilities. Self-onsistent radiative heating, representing enhanced/reduced FUV photons from the star formation, s also taken into account. Evolution of our model disks is highly dynamic, but reaches a quasi-teady state. The disks are overall in effective hydrostatic equilibrium with the midplane thermal ressure set by the vertical gravity. The star formation rate is found to be proportional pproximately linearly to the midplane thermal pressure. These results are in good agreement with the predictions of a recent theory by Ostriker, McKee, and Leroy (2010) for the thermal/dynamic equilibrium model of star formation regulation.