• Journal of Korea Multimedia Society
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• v.24 no.4
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• pp.528-537
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• 2021

Face recognition has gained significant notice because of its application in many businesses: security, healthcare, and marketing. In this paper, we will present the recognition method using the combination of correlation filters (CF) and Support Vector Machine (SVM). Firstly, we evaluate the performance and compared four different correlation filters: minimum average correlation energy (MACE), maximum average correlation height (MACH), unconstrained minimum average correlation energy (UMACE), and optimal-tradeoff (OT). Secondly, we propose the machine learning approach by using the OT correlation filter for features extraction and SVM for classification. The numerical results on National Cheng Kung University (NCKU) and Pointing'04 face database show that the proposed method OT-SVM gets higher accuracy in face recognition compared to other machine learning methods. Our approach doesn't require graphics card to train the image. As a result, it could run well on a low hardware system like an embedded system.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.64.2-64.2
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• 2012

The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation infrared space telescope optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. It will achieve the high resolution as well as the unprecedented sensitivity from mid to far-infrared range. The FPC (Focal Plane Camera) is a Korean-led near-infrared instrument as an international collaboration. The FPC-S and FPC-G are responsible for the scientific observation in the near-infrared and the fine guiding, respectively. The FPC-G will significantly reduce the alignement and random pointing error through the observation of guiding stars in the focal plane. We analyzed the pointing requirement from the focal plane instruments. The feasibility study was performed to achieve the requirements. Here, we present the role of SPICA/FPC as a fine guiding camera.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1126-1129
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• 2003

In this paper, we propose a multi-agent system for assisting those who need help in taking objects around him/her. One may imagine this kind of situation when a person is lying in bed and wishes to take an object on a distant table that cannot be reached only by stretching his/her hand. The proposed multi-agent system is composed of three main independent agents; a vision agent, a robot agent, and a pass agent. Once a human expresses his/her intention by pointing to a particular object using his/her hand and a finger, these agents cooperatively bring the object to him/her. Natural communication between a human and the multi-agent system is realized in this way. Performance of the proposed system is demonstrated in an experiment, in which a human intends to take one of the four objects on the floor and the three agents successfully cooperate to find out the object and to bring it to the human.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.443-447
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• 2000

Chonan and Asan city have been a focal point due to rapid development as the first station for Express Railroad and key cities West Coast Development Region. Gokgyo stream adjacent to the cities plays an important role as a drainage channel for an agriculture and a discharger of urban storm water. Waster quality of the stream has been deteriorating caused by pollution sources such as a untreated wastewater discharge and runoff from the watershed. In the study, we conducted 4 surveys in April, May, July, and September to understand the current state of water quality for the stream and to make it possibe to predict future water-quality variation for future development. The system runs on a personal computer under the windows enviroment and provides extensive graphic user interface(GUI) for user-friendly assessment. Using the pull-down menus provided by the GUI panel, the user is able to operate the system by pointing and clicking the icon to identify the state of water-quality at locations concerned. Furthermore, we developed an integrated watershed management system. The constructed system could be a useful tool as a decesion maker for pollution source control strategy.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.742-745
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• 2009

This paper proposes a wireless LAN antenna system that tracks an object automatically by using image-based tracking. The proposed system consists of a camera and a pan-tilt unit in addition to a directional wireless LAN antenna. The camera and the directional antenna are set in same direction and they are set on the pan-tilt unit. A target object which has a wireless LAN receiver is tracked by using images captured by the camera. And the directional antenna faces in same direction as the camera by the pan-tilt unit. Therefore, the directional antenna keeps pointing the receiver, and a transmitting efficiency is improved. A result of a fundamental experiment shows that a receiver attached to a flying airship was tracked by a prototype of the proposed antenna system. The airship flied about, and the proposed antenna system was set on a roof of a building. The experimental result indicates an effectiveness of the proposed system compared to the conventional directional LAN antenna.

• Current Optics and Photonics
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• v.5 no.2
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• pp.114-120
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• 2021

Free-space optical (FSO) communication is considered to be a potential solution to congestion in the radio-frequency spectrum and last-mile-access bottleneck issues in future cellular communication networks, such as 5G and beyond. However, FSO link performance may degrade significantly due to irradiance fluctuations and random temporal fluctuations from atmospheric turbulence. Therefore, in this work the main objective is to reduce the effect of the atmospheric turbulence by considering a multihop FSO communication system with amplify-and-forward relaying supported by a radio-frequency (RF) link, which form a hybrid FSO/RF communication system. The FSO link is assumed to follow the gamma-gamma fading model, which represents strong turbulence. Also, the RF link is modeled by a Rayleigh distribution. The performance of the considered system, in terms of the outage probability and average bit-error rate (BER), is investigated and analyzed under various weather conditions and pointing errors. Furthermore, the effect of the number of employed relay nodes on the performance of the system is investigated. The results indicate that the considered system reduces outage probability and average BER significantly, especially for low channel quality. Finally, the closed-form expressions derived in this work are compared to the results of Monte Carlo simulations, for verification.

• The Journal of Korea Robotics Society
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• v.15 no.1
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• pp.16-23
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• 2020

This paper describes an alignment algorithm that estimates the initial heading angle of AUVs (Autonomous Underwater Vehicle) for starting navigation in a sea area. In the basic dead reckoning system, the initial orientation of the vehicle is very important. In particular, the initial heading value is an essential factor in determining the performance of the entire navigation system. However, the heading angle of AUVs cannot be measured accurately because the DCS (Digital Compass) corrupted by surrounding magnetic field in pointing true north direction of the absolute global coordinate system (not the same to magnetic north direction). Therefore, we constructed an experimental constraint and designed an algorithm based on extended Kalman filter using only inertial navigation sensors and a GPS (Global Positioning System) receiver basically. The value of sensor covariance was selected by comparing the navigation results with the reference data. The proposed filter estimates the initial heading angle of AUVs for navigation in a sea area and reflects sampling characteristics of each sensor. Finally, we verify the performance of the filter through experiments.

• Journal of Astronomy and Space Sciences
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• v.22 no.1
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• pp.35-46
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• 2005

This paper addresses the design and analysis results of a 2-axes magnetometer for attitude determination of small satellite. A low-cost and efficient 2-axes fluxgate magnetometer was selected as the most suitable attitude sensor for LEO microsatellites which require a low-to-medium level pointing accuracy. An optimization trade-off study has been performed for the development of 2-axes fluxgate magnetometer. All the relevant parameters such as permeability, demagnetization factor, coil diameter, core thickness, and number of coil turns were considered for the sizing of a small satellite magnetometer. The magnetometer which is designed, manufactured, and tested in-house as described in this paper satisfies linearity requirement for determining attitude position of small satellites. On the basis of magnetometer which is designed in Space System Research Lab. (SSRL), commercial magnetometer will be developed.

• Journal of Astronomy and Space Sciences
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• v.22 no.1
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• pp.47-58
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• 2005

This paper addresses development of the ultra-light analog sun sensors for small satellite applications. The sun sensor is suitable for attitude determination for small satellite because of its small, light, low-cost, and low power consumption characteristics. The sun sensor is designed, manufactured and characteristic-tested with the target requirements of ${\pm}60^{\circ}$ FOV (Field of View) and pointing accuracy of ${\pm}2^{\circ}$. Since the sun sensor has nonlinear characteristics between output measurement voltage and incident angle of sunlight, a higher order calibration equation is required for error correction. The error was calculated by using a polynomial calibration equation that was computed by the least square method obtained from the measured voltages vs. angles characteristics. Finally, the accuracies of 1-axis and 2-axes sun sensors, which consist of 2 detectors, are compared.

• Journal of Astronomy and Space Sciences
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• v.25 no.3
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• pp.239-244
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• 2008

Two kinds of important issues on Titius-Bode's relation have been discussed up to now: one is if there is a simple mathematical relation between distances of natural bodies orbiting a central body, and the other is if there is any physical basis for such a relation. These may be tackled by answering a question whether Titius-Bode's relation is valid universally in exo-planetary systems. We have examined whether Titius Bode's relation is also applicable to exo-planetary systems by statistically studying the distribution of the ratio of rotational periods of two planets in an exo-planetary system, 55 Cnc, by comparing it with that derived from Titius-Bode's relation. We find that the distribution of the ratio of rotational periods of randomly chosen two planets in the 55 Cnc system is apparently inconsistent with that derived from Titius-Bode's relation. The probability that two data sets are drawn from the same distribution function is 50%. We also find that the Fourier power spectra show that the distribution of the semi-major axis of planets in the 55 Cnc system seems to be stretched. We conclude by pointing out that large numbers of planets should be examined to more convincingly explain the distribution of the distance of planetary formation regions.