• Journal of the Korea Society of Computer and Information
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• v.19 no.1
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• pp.23-30
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• 2014

Feature matching using image descriptors is robust method used recently. However, mismatches occur in 3D transformed images, illumination-changed images and repetitive-pattern images. In this paper, we observe that there are a lot of mismatches in the images which have repetitive patterns. We analyze it and propose a method to eliminate these mismatches. MDMF(Multiple Descriptors-based Mismatch Filtering) eliminates mismatches by using descriptors of nearest several features of one specific feature point. In experiments, for geometrical transformation like scale, rotation, affine, we compare the match ratio among SIFT, ASIFT and MDMF, and we show that MDMF can eliminate mismatches successfully.

• Journal of Broadcast Engineering
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• v.2 no.1
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• pp.74-83
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• 1997

We have proposed a composite feature measure which combines the color and shape features of an image for image retrieval. We improved the performance of retrieval based on the efficient color quantization using the Lloyd-Max quanizer and on the Histogram matrix matching method which considers the spatial correlation of quantized color group. We also supplemented the color information using shape information with the Improved Moment Invarlants. We have tested our technique on Image database consisting of 200 actual trademark images. Our experimental results showed that our approach improved the performance compared to the previous method under the various situations such as rotation images, translation images, noise added images, gamma corrected images and so on. The efficiency of retrieval is found to be very high and experimental results are

• Journal of the Korean Society for Precision Engineering
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• v.32 no.7
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• pp.633-641
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• 2015

In this study, we proposed a three-dimensional (3D) scanning system based on laser-vision technique and rotary mechanism for automatic 3D model reconstruction. The proposed scanning system consists of a laser projector, a camera, and a turntable. For laser-camera calibration a new and simple method was proposed. 3D point cloud data of the surface of scanned object was fully collected by integrating extracted laser profiles, which were extracted from laser stripe images, corresponding to rotary angles of the rotary mechanism. The obscured laser profile problem was also solved by adding an addition camera at another viewpoint. From collected 3D point cloud data, the 3D model of the scanned object was reconstructed based on facet-representation. The reconstructed 3D models showed effectiveness and the applicability of the proposed 3D scanning system to 3D model-based applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4733-4738
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• 2013

This paper proposes a method to obtain the dynamic equilibrium configuration of a constrained mechanical system by using multibody dynamic analysis. Dynamic equilibrium equations with independent coordinates are derived from the time-dependent constraint equations and dynamic equations of a multibody system. The Newton-Raphson method is used to find numerical solutions for nonlinear algebraic equations that are composed of the dynamic equilibrium and constraint equations. The proposed method is applied to obtain the dynamic equilibrium configuration of a speed governor, and the results are verified on the basis of the results from conventional dynamic analysis. Furthermore, vertical displacements at equilibrium configuration, which varied with the rotational velocity of the speed governor, are calculated, and design parameter analysis of the equilibrium configuration is presented.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.4 s.310
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• pp.96-107
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• 2006

In this paper, a low bitrate video coding method based on new panoramic modeling is proposed for panning cameras. An input video frame from a panning camera is decomposed into a background image, rectangular moving object regions, and a residual image. In coding the background, we employ a panoramic model that can account for several image formation processes, such as perspective projection, lens distortion, vignetting and illumination effects. Moving objects aredetected, and their minimum bounding rectangular regions are coded with a JPEG-2000 coder. We have evaluated the effectiveness of the proposed algorithm with several indoor and outdoor sequences and found that the PSNR is improved by $1.3{\sim}4.4dB$ compared to that of JPEG-2000.

• Publications of The Korean Astronomical Society
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• v.21 no.2
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• pp.75-79
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• 2006

An alt-azimuth type mount system, developed at the Space Science and Technology Laboratory, Kyung Hee University, has been found to experience some difficulties in monitoring of the artificial space objects. Since the telescope installed on the alt-azimuth mount does not rotate on the same axis as the earth does, this mount system needs an instrument rotator to correct the field rotation. Although there are some commercial instrument rotators already in the market, those are not suitable for our system due to their low interchangeability. In this study, we have designed a new high speed instrument rotator and calculated the deformation of new designed system using structural analyses.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.693-700
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• 2003

An evaluation method for flutter derivatives is proposed, using indicial functions of structural members produced by Computational Fluid Dynamics (CFD). Flutter derivatives are obtained by Fourier integration of indicial functions. Instead of direct simulation of oscillating objects, only the calculation of time-dependent lift and moment variations of fixed objects with constant attack angle are necessary.The Finite Element Method (FEM) is developed as a tool for the numerical method. For two rectangular sections having different aspect ratios, the numerical analysis and wind tunnel test are carried out to inspect the adequacy of this study. The results proved to be good, and they could be used for a preliminary design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1126-1131
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• 2001

Excessive vibration in rotating machinery is a problem encountered in many different fields, causing such difficulties as fatigue of machinery components and failure of supporting bearings. Passive techniques, though sometimes limited in their capabilities, have been used in the past to attenuated vibrations. Recently active techniques have been developed to provide vibration control perform beyond that provided by their passive counters. Most often, the focus of active control methods has been to suppress rotating machinery displacements. In cases where vibration results in bearing failures, displacement suppression may not be the best choice of control approaches (it can, in fact, increase dynamic bearing loads which would be even more harmful to bearings). This paper presents two optimal control methods for attenuating steady state vibrations in rotating machinery. One method minimizes shaft displacements while the other minimizes dynamic bearing reaction forces. The two methods are applied to a model of a typical rotating machinery system and their results are compared. It is found that displacement minimization can increase bearing loads, while bearing load minimization, on the other hand, decreases bearing loads.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.11-14
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• 2012

본 논문에서는 임베디드 시스템 기반 NXT 로봇을 제어하여 길찾기, 미로찾기, 장애물오르기 등의 주행을 수행하는 프로그램을 개발하는 것이다. 미로 찾기는 RBG 센서를 통해 트랙의 색을 구분하여 정해진 색을 따라 주행하는 하는 것이며, 장애물 미로구간에서는 NXT 로봇 자신이 장애물을 넘지 못한다는 것을 인식하여 미로를 찾아 빠져나가도록 초음파 센서를 이용한다. 초음파 센서로 자신이 통과할 수 있는 진입로로 판단되면 주행을 계속하며, 그렇지 않은 경우에는 좌우회전을 통해 미로구간을 통과한다. 마지막 계단식 장애물 구간에서는 접촉센서와 초음파 센서를 통해서 물체의 높이를 가늠하여, 접촉센서 값과 초음파 센서 값을 통해 프로그램은 통과 여부와 계단높이를 판단한다. 실험결과 로봇은 제어프로그램 시나리오에 따라 적절하게 수행함을 확인할 수 있었으며, 이와 같은 로봇 제어를 확대하면 사람을 대신하는 재난구조 활동, 전쟁시 지뢰탐지 및 적 정찰활동, 지하공동구 및 지하매설물 안전 점검활동 등을 수행하는 업무로 적용이 가능할 것으로 판단된다. 본 연구에서 사용한 로봇은 I-Brick이라는 마이크로프로세서를 통해 프로그램을 구동되며, 저 전력으로 I-Brick과 그와 연결된 센서와 서브 모터 등을 구동하고 제어하도록 설계하였다.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.624-631
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• 2008

This paper presents a method for a mobile robot to follow a moving object in real time. The robot follows a target object keeping the facing angle toward the target and the distance to the target to given value. The method consists of two procedures: first, the detection of target position in the robot coordinate system, and the second, the calculation of translational velocity and rotational velocity to follow the object:. To detect the target location, range sensor data is represented in histogram. Based on the real time calculation of the location of the target relative to the robot, translational velocity and rotational velocity to follow the target are calculated. The velocities make the heading angle and the distance to target converge toward the desired ones. The performance of the method is tested through simulation. In the simulation, the target moves with three different trajectories, straight line trajectory, rectangular trajectory, and circular trajectory. As shown in the results, it is inevitable to lose track temporarily of the target when the target suddenly changes its motion direction. Nevertheless, the robot speeds up to catch up and finally succeeds to follow the target as soon as possible even in this case. The proposed method can also be utilized to coordinate the motion of multiple robots to keep their formation as well as to follow a target.