• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.584-587
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• 2002

A vision sensor measure range data using laser light source. This sensor generally use patterned laser which shaped single line. But this vision sensor cannot satisfy new trend which needs laster and more precise processing. The sensor's sampling rate increases as reduced image processing time. However, the sampling rate can not over 30fps, because a camera has mechanical sampling limit. If we use multi line laser pattern, we will measure multi range data in one image. In the case of using same sampling rate camera, number of 2D range data profile in one second is directly proportional to laser line's number. For example, the vision sensor using 5 laser lines can sample 150 profiles per second in best condition.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.2
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• pp.108-115
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• 2002

The fundamental mechanism of a dispersed two-phase flow was investigated. Experiments were carried out to understand how the particles behaves under the influence of the particle size, shape, metamorphoses (bubble) and buoyancy of a single particle which is ascending from the standstill water. Two CCD cameras were employed for image processing of the behavior of the particles and the surrounding flow, which was interpreted with the technique of correlation PIV (Particle Image Velocimetry) and PTV (Particle Tracking Veloci- metry), respectively The experimental results showed that the large density difference bet- ween a particle and water caused high relative velocity and induced zigzag motion of the particle. Furthermore, the turbulence intensity of a bubble was about twice the case of the spherical solid particle of similar diameter.

• Proceedings of the IEEK Conference
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• summer
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• pp.110-113
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• 2004

Underwater acoustic(UWA) communication is one of the most difficult field because of several factors such as multipath propagation, high temporal and spatial variability of channel conditions. Therefore, it is important to model and analyze the characteristics of underwater acoustic channel such as multipath propagation, transmission loss, reverberation, and ambient noise. In this paper, UWA communication channel is modeled with a ray tracing method and applied to image transmission. Quadrature phase shift keying(QPSK) and multichannel decision feedback equalizer(DFE) are utilized as phase-coherent modulation method and equalization technique, respectively. The objective is to improve the performance of vertical sensor array than that of single sensor in the viewpoint of bit error rate(BER), constellation output, and received image quality.

• IE interfaces
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• v.8 no.1
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• pp.5-13
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• 1995

Automated vision inspection has become a vital part of computer related industries. Most of the existing inspection systems mainly utilize black and white images. In this paper, we consider an application of automated vision inspection in which cable color has to be recognized in order to detect the quality status of assembled wire harness. A back-propagation neural network is proposed to classify seven different cable colors. To represent a single point in image space, we use the ($L^*,\;a^*,\;b^*$) model which is one of commonly used color-coordinate systems in image processing. After training the neural network with ($L^*,\;a^*,\;b^*$) data obtained from color image, we tested its performance. The results show that the neural network is able to classify cable colors with high performance.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1755-1760
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• 2004

The holographic velocimetry system has a significant potential for the measurements of three dimensional velocities of particles. In this study, orthogonal two-side holography system was developed to obtain three dimensional velocities and sizes of spray droplets. To get high quality of reconstructed images, singe-exposure holography at two time moments and two orthogonal sides was adopted instead of multi-exposure, single-side holography. From three dimensional positions of droplets determined by reconstruction and image processing system, the three dimensional velocities and sizes of each droplet was extracted using the PTV algorithm. To determine the position of particles in the optical axis, a new focusing parameter was introduced based on the correlation between two droplet images at the same distance. The measured results by holography system were compared with those by the PDPA.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.851-854
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• 2000

Digital halftoning is a technique to make an equivalent binary image from scanned photo or graphic images. Low pass filtering characteristic of human visual system can be applied to get the effect of spatial averaging of local area consisted of black and white pixels for gray image. The overlapping of black dot decreases brightness and black dot is very sensitive to human visual system in the bright region. In this paper, for gray-level expression, only bright gray region in the color image is considered for blue noise mask (BNM) approach. To solve this problem, BNM with CMY dot is used for the bright region instead of black dot. Dot-on-dot model with single mask causes the problem making much black dot overlap, color distortion. Therefore approach with three masks for C, M and Y each is proposed to decrease pixel overlap and color distortion.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.4
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• pp.216-223
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• 2015

The autonomous underwater vehicle (AUV) is being widely researched in order to achieve superior performance when working in hazardous environments. This research focuses on using image processing techniques to estimate the AUV's egomotion and the changes in orientation, based on image frames from different time frames captured from a single high-definition web camera attached to the bottom of the AUV. A visual odometry application is integrated with other sensors. An internal measurement unit (IMU) sensor is used to determine a correct set of answers corresponding to a homography motion equation. A pressure sensor is used to resolve image scale ambiguity. Uncertainty estimation is computed to correct drift that occurs in the system by using a Jacobian method, singular value decomposition, and backward and forward error propagation.

• Nuclear Engineering and Technology
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• v.40 no.5
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• pp.419-428
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• 2008

During the overhaul period of nuclear power plants in Korea, an ROV(Remotely Operated Vehicle) enters the cold-leg pipes connected with the reactor to examine the state of the thermal sleeves and their positions in the safety injection nozzles. To measure the positions of the thermal sleeves or scratches with video images recorded during the examination, time-varying camera parameters should be known, such as the focal length and principal points used for the capturing each video image. In this paper, we propose a camera calibration and measurement scheme by using a single image containing two circular grooves of a cylindrical nozzle whose radius and distance are known.

• Annual Conference of KIPS
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• 2002.11a
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• pp.775-778
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• 2002

영상 이진화란 명도 영상(gray-scaled image)을 이진 영상(bi-leveled image)으로 변환하는 것을 말한다. 영상 이진화는 문서 인식, 비디오 영상 분석 등과 같이 영상처리 분야에서 많이 사용되는 기본적인 영상 처리 과정에 해당한다. 본 논문은 Intel 사의 Pentium 계열 프로세서에서 지원하는 SIMD(Single-Instruction Multiple-Data) 기술을 이용하여 영상 이진화를 고속으로 수행하는 방법을 소개한다. 우편영상에 대하여 실험한 결과, SSE2 명령어로 구현된 프로그램은 기존의 C 언어로 구현된 프로그램에 비하여 4배 이상의 속도 향상을 보였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1407-1417
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• 2016

In this paper, we propose a multi-level content transmission mechanism for intelligent quality of service (QoS) in social networking services (SNSs). Because existing SNSs and related work send image content to a client with a single fixed mechanism, they cannot consistently support content accessibility according to different conditions of QoS factors such as network congestion and throughput. In the proposed image transmission mechanism, our communication middleware (CM) provides an SNS developer with three transmission modes so that an SNS server or client can dynamically change the quality of images if required. In each transmission mode, an SNS server can send images to a requesting client with original high quality, thumbnail quality, or send only text information. With varying qualities of downloaded images, an SNS developed on top of CM can provide users with consistent QoS for access to SNS content.