• Journal of Institute of Control, Robotics and Systems
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• 제14권8호
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• pp.774-778
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• 2008

The inaccuracy of inertial sensors used in low cost IMU's limits the usage to ARS, at best. Sensor fusion technologies are widely used to overcome this problem. GPS is the most popular secondary sensor, but GPS alone cannot fully compensate the IMU errors in the initial alignment process and rectilinear flights. This paper presents a new concept of aiding the low cost IMU with the sun line of sight vector. The simulation and experimental results in this paper proves that aiding of INS/GPS with the sun line of sight vector increases the observability and improves accuracy remarkably.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제47권3호
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• pp.220-227
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• 2019

The satellites in orbit use a sun reference vector from solar model based the ephemeris. To get the ephemeris, we use DE-Series, an ephemeris developed by the Jet Propulsion Laboratory (JPL), or the reference vector generation formula proposed by Vallado. The DE-Series provides the numerical coefficients of Chebyshev polynomials, which have the advantage of high precision, but there is a computational burden on the satellite. The Vallado's method has low accuracy, although the sun vector can be easily obtained through the sun vector generation equation. In this paper, we have developed a program to provide the Chebyshev polynomial coefficients to obtain the sun position coordinates in the inertial coordinate system. The proposed method can improve the accuracy compared to the conventional method and can be used for high - performance, high - precision nano satellite missions.

• Journal of the Korean Mathematical Society
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• 제45권6호
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• pp.1677-1703
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• 2008

In this paper, we introduce and study various locally convex vector topologies on the space of bounded linear operators between Banach spaces. We also apply these topologies to approximation properties.

• Bulletin of the Korean Mathematical Society
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• 제55권5호
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• pp.1339-1350
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• 2018

We will find a necessary and sufficient condition for unit Killing vector fields to be minimal and provide an application of the obtained result.

• Structural Engineering and Mechanics
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• 제62권6호
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• pp.709-717
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• 2017

This paper develops a two-stage method for structural damage identification by using modal data. First, the Residual Force Vector (RFV) is introduced to detect any potentially damaged elements of structures. Second, data of the frequency domain are used to build up the objective function, and then the Imperialist Competitive Algorithm (ICA) is utilized to estimate damaged extents. ICA is a heuristic algorithm with simple structure, which is easy to be implemented and it is effective to deal with high-dimension nonlinear optimization problem. The advantages of this present method are: (1) Calculation complexity can be decreased greatly after eliminating many intact elements in the first step. (2) Robustness, ICA ensures the robustness of the proposed method. Various damaged cases and different structures are investigated in numerical simulations. From these results, anyone can point out that the present algorithm is effective and robust for structural damage identification and is also better than many other heuristic algorithms.

• Journal of the Korean Society of Industry Convergence
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• 제23권6_2호
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• pp.1025-1032
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• 2020

In this paper, we propose a method to classify road weather conditions into rain, fog, and sun using a SVM (Support Vector Machine) classifier after extracting weather features from images acquired in real time using an optical sensor installed on a roadside post. A multi-dimensional weather feature vector consisting of factors such as image sharpeness, image entropy, Michelson contrast, MSCN (Mean Subtraction and Contrast Normalization), dark channel prior, image colorfulness, and local binary pattern as global features of weather-related images was extracted from road images, and then a road weather classifier was created by performing machine learning on 700 sun images, 2,000 rain images, and 1,000 fog images. Finally, the classification performance was tested for 140 sun images, 510 rain images, and 240 fog images. Overall classification performance is assessed to be applicable in real road services and can be enhanced further with optimization along with year-round data collection and training.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.679-682
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• 1997

This paper presents finite element analysis algorithm combined with vector hysteresis model for accurate analysis of the hysteresis motor. Magnetization-dependent vector model is adapted to calculate the vector magnetization. That is to say, from the magnitude and direction of the magnetic field intensity, the magnetization of each ring element is computed by the vector model. By comparing the simulation results with the experimental ones, it is found that good results are obtained.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제55권6호
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• pp.299-305
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• 2006

In this paper, we suggest a new space vector PWM modulation method with very short processing time which does not need identification of nearest three vectors(NTV) and duty ratio for each vector. The suggested PWM method makes mean value of phase voltage to be same as reference during every modulation period by use of a triangle in small hexagon on multi-level vector space. This paper described the suggested modulation method can be successfully applied to the space vector modulation use of multi-level inverter by computer simulations and experiments.

• Journal of The Korean Astronomical Society
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• 제32권2호
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• pp.127-136
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• 1999

In this study we present the study of solar active regions based on BOAO vector magnetograms and H$\alpha$ filtergrams. With the new calibration method we analyzed BOAO vector magnetograms taken from the SOFT observational system to compare with those of other observing systems. In this study it has been demonstrated that (1) our longitudinal magnetogram matches very well the corresponding Mitaka's magnetogram to the extent that the maximum correlation yields r=0.962 between our re-scaled longitudinal magnetogram and the Mitaka's magnetogram; (2) according to a comparison of our magnetograms of AR 8422 with those taken at Mitaka solar observatory their longitudinal fields are very similar to each other while transverse fields are a little different possibly due to large noise level; (3) main features seen by our longitudinal magnetograms of AR 8422 and AR 8419 and the corresponding Kitt Peak magnetograms are very similar to each other; (4) time series of our vector magnetograms and H-alpha observations of AR 8419 during its flaring (M3.1/1B) activity show that the filament eruption followed the sheared inversion line of the quadrupolar configuration of sunspots, indicating that the flare should be associated with the quadrupolar field configuration and its interaction with new filament eruption. Finally, it may be concluded that the Solar Flare Telescope at BOAO works normally and it is ready to do numerous observational and theoretical works associated with solar activities such as flares.

• Journal of the Korean Mathematical Society
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• 제10권2호
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• pp.77-80
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• 1973