• Proceedings of the KSME Conference
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• 2001.06e
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• pp.548-554
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• 2001

A GA(Genetic Algorithm) based 3D-PTV technique has been developed. The measurement system consists of three CCD cameras, Ar-ion laser, an image grabber and a host computer. The fundamental of the developed technique was based on that one-to-one correspondence is found between two tracer particles selected at two different image frames taking advantage of combinatorial optimization of the genetic algorithm. The fitness function controlling reproductive success in the genetic algorithm was expressed by a kind of continuum theory on the sparsely distributed particles in space. In order to verify the capability of the constructed measurement system, a performance test was made using the LES data set of an impinging jet. The developed 3D-PTV system was applied to the measurement of flow characteristics of the wake of a circular cylinder.

• Journal of Korea Multimedia Society
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• v.21 no.10
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• pp.1162-1170
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• 2018

This paper presents an augmented reality system for multiple users. The proposed system performs ar image-based pose estimation of users and pose of each user is shared with other uses via a network server. For camera-based pose estimation, we install multiple markers in a pre-determined space and select the marker with the best appearance. The marker is detected by corner point detection and for robust pose estimation. the marker's corner points are tracked by optical flow tracking algorithm. Experimental results show that the proposed system successfully provides an augmented reality application to multiple users even when users are rapidly moving and some of markers are occluded by users.

• Journal of Korea Multimedia Society
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• v.23 no.3
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• pp.395-401
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• 2020

In this paper, a motion-based ROI extraction algorithm from a high resolution fisheye image is proposed for multi-view monitoring systems. Lately fisheye cameras are widely used because of the wide angle-of-view and they basically provide a lens correction functionality as well as various viewing modes. However, since the distortion-free angle of conventional algorithms is quite narrow due to the severe distortion ratio, there are lots of unintentional dead areas and they require much computation time in finding undistorted coordinates. Thus, the proposed algorithm adopts an image decimation and a motion detection methods, that can extract the undistorted ROI image with a standard angle-of-view for the fast and intelligent surveillance system. In addition, a mesh-type ROI is presented to reduce the lens correction time, so that this independent ROI scheme can parallelize and maximize the processor's utilization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1842-1848
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• 2002

Although DLC coatings have good tribological properties, these are dependant on the deposition method, the property of contact surface, and test condition. Humidity, which has little influence on tribological behavior in macro scale, is an important factor of tribological behavior in small devices like MEMS. The objective of this study is to investigate the tribological behavior of DLC coatings with particular attention to their wettability at various humidities. DLC coatings were deposited on Si substrates and tested using a reciprocating friction tester against Si$_3$N$_4$balls at various humidities. The results showed that the tribological behavior of DLC coatings was dependant on relative humidity and wettablility of DLC coatings. Friction coefficient at high relative humidity was higher thar that at low relative humidity. The tungsten-containing DLC coatings had a good wear resistance at low relative humidity whereas DLC coatings derived from argon(Ar)+cesium(Cs) gases showed a good wear resistance at high relative humidity.

• Journal of the Korean Society of Visualization
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• v.7 no.1
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• pp.9-13
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• 2009

Fluorescence recovery after photobleaching (FRAP) has been widely used for the measurement of molecular diffusion in living cells and tissues. We developed an image-based FRAP (iFRAP) technique using a modified real-time microscope and a 488 nm Ar-ion laser. A fractional intensity curve was obtained from the time-lapse images of fluorescence recovery in the bleached spot to determine the diffusion coefficient of fluorescently labeled macromolecules in porous medium. We validated iFRAP through experiments with agar gels (0.5% and 1.5% w/v) containing FITC-Dextrans (10, 70 and 500 kDa MW). Further validation was performed by a Monte Carlo approach, where we simulated the three-dimensional random walk of macromolecules in agar gel model. Diffusion coefficients were deduced from the mean square displacement curves and showed good agreements with those measured by iFRAP.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.20-28
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• 2010

In this paper, we propose a hand gesture interface for the manipulation of augmented objects in 3D space using a camera. Generally a marker is used for the detection of 3D movement in 2D images. However marker based system has obvious defects since markers are always to be included in the image or we need additional equipments for controling objects, which results in reduced immersion. To overcome this problem, we replace marker by planar hand shape by estimating the hand pose. Kalman filter is for robust tracking of the hand shape. The experimental result indicates the feasibility of the proposed algorithm for hand based AR interfaces.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.863-868
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• 2003

Mixers are used in various industrial fields where it is necessary to intimately mix two reactants in a short period of time. However, despite their widespread use, complex unsteady flow characteristics of industrial mixers are not systematic investigated. The present study aimed to clarify unsteady flow characteristics induced by various impellers in a tank. Impellers arc hydrofoil turbine and neo-hydrofoil turbine types. A high speed CCD camera and an Ar-Ion laser for illumination were adopted to clarify the time-dependent flow characteristics of the mixers. The rotating speed of impellers increased from 6Hz to 60Hz by 6Hz, The maximum velocity around neo-hydrofoil impeller is higher than the hydrofoil type impeller. These two types of turbine shows that typical flow characteristics of axial turbine and suitable for mixing high-viscosity materials.

• Journal of Korean Society for Geospatial Information Science
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• v.6 no.1 s.11
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• pp.19-26
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• 1998

In general, GIS provides a user with geographical information according to his requirements after a computer stores digitized spatial data from real scenes. Geographical information from digitized spatial data lacks of reality due to the exclusion of real scenes. However, Augmented Reality(AR) allows a user to see the real world with virtual objects superimposed upon or composited with the real world. Therefore it enhances a user's perception of the real world. In this paper, we present the development on 3D geographical information guide system using augmented reality that displays the real world with virtual objects such as building name, road name, etc., in real time.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.201-209
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• 2017

This paper is a smartphone object recognition system using hierarchical convolutional neural network. The overall configuration is a method of communicating object information to the smartphone by matching the collected data by connecting the smartphone and the server and recognizing the object to the convergence neural network in the server. It is also compared to a hierarchical convolutional neural network and a fractional convolutional neural network. Hierarchical convolutional neural networks have 88% accuracy, fractional convolutional neural networks have 73% accuracy and 15%p performance improvement. Based on this, it shows possibility of expansion of T-Commerce market connected with smartphone and broadcasting media.

• Journal of Korea Game Society
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• v.20 no.5
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• pp.13-20
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• 2020

Biometric technology with the advance of deep learning enabled the new types of content. Especially, face recognition can provide immersion in terms of convenience and non-compulsiveness, but most commercial content has limitations that are limited to application areas. In this paper, we attempted to overcome these limitations, implement content that can utilize face recognition technology based on realtime video feed. We used Unity engine for high quality graphics, but performance degradation and frame drop occurred. To solve them, we augmented Dlib toolkit and adjusted the resolution image.