• 한국수산과학회지
• /
• 제55권2호
• /
• pp.195-206
• /
• 2022

The separation of spectrally overlapped broadband echo signals from free-swimming Japanese needlefish Hypohamphus sajori using the fractional Fourier transform (FrFT) was investigated. The broadband echo signals were measured over frequency ranges of 40-80 and 110-220 kHz. The overlapped echo signals were separated after eliminating noise signals in the smoothed pseudo-Wigner-Ville distribution domain. The echo signal from a 40 mm WC sphere suspended just below a chirp transducer was used to calibrate the broadband of the chirp echo sounder and estimate the frequency dependence of target strength for the separated echo signals. The experimental results show that the proposed FrFT method can analyze the time-frequency image of broadband echo signals from free-swimming individual fish effectively and can be used as a quantitative tool for extracting the acoustic features used for fish species identification.

• 천문학회지
• /
• 제29권2호
• /
• pp.119-136
• /
• 1996

To examine the effect of neighboring galaxies on the gravitational lensing statistics, we performed numerical simulations of lensing by many galaxies. The models consist of a galaxy in the rich cluster like Coma, or a galaxy surrounded by field galaxies in $\Omega_0 = 1$ universe with $\Omega_{gal} = 0.1,\;\Omega_{gal} = 0.3\;or\;\Omega_{gal}=1.0\;,\;where\;\Omega_{gal}$ is the total mass in galaxies. Field galaxies either have the same mass or follow Schechter luminosity function and luminosity-velocity relation. Each lensing galaxy is assumed to be singular isothermal sphere (SIS) with finite cutoff radius. In most simulations, the lensing is mainly due to the single galaxy. But in $\Omega_{gal} = 3$ universe, one out of five simulations have 'collective lensing' event in which more than two galaxies collectively produce multiple images. These cases cannot be incorporated into the simple 'standard' lensing statistics calculations. In cases where 'collective lensing' does not occur, distribution of image separation changes from delta function to bimodal distribution due to shear induced by the surrounding galaxies. The amount of spread in the distribution is from a few $\%\;up\;to\;50\%$ of the mean image separation in case when the galaxy is in the Coma-like cluster or when the galaxy is in the field with $\Omega_{gal} = 0.1\;or\;\Omega_{gal}=0.3.$ The mean of the image separation changes less than $5\%$ compared with a single lens case. Cross section for multiple image lensing turns out to be relatively insensitive to the presence of the neighboring galaxies, changing less than $5\%$ for Coma-like cluster and $\Omega_{gal}=0.1,\;0.3$ universe cases. So we conclude that Coma-like cluster or field galaxies whose total mass density $\Omega_{gal}<0.3$ do not significantly affect the probability of multiple image lensing if we exclude the 'collective lensing' cases. However, the distribution of the image separations can be significantly affected especially if the 'collective lensing' cases are included. Therefore, the effects of surrounding galaxies may not be negligible when statistics of lensing is used to deduce the cosmological informations.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 추계종합학술대회 논문집
• /
• pp.1081-1084
• /
• 1999

This paper proposes a method of extracting automobile license plate information using color image processing and separation of character regions. The hue and saturation of color information is need for license plate extraction and the specified standard location ratio is need for character region separation. Simulation results show that the proposed algorithm can detect license plates and separate character regions successfully.

• Journal of Advanced Marine Engineering and Technology
• /
• 제25권2호
• /
• pp.365-374
• /
• 2001

Its a tendency to strengthen related international was as the importance on marine oil pollution recently becomes the issue. According to the regulation of IMO, oil discharge from ships is allowed under 15PPM only and oil filtering equipment is essential. Oily water separator of laminated plate type which is one of gravity type separator can be use as assistant equipment for the oil filtering system to meet the present IMO standard, because it fits well to process large amount of rich oil with high specific gravity. The purpose of this paper is to investigate an efficiency of oil/water separation with the characteristics of laminated plate arrangement. The analyse of oil contents for oil-water mixture were carried out in order to find an efficiency of oil/water separation and an experimental study was simultaneously carried out to investigate internal flow characteristics of separator by visualization method and PIV(Particle Image Velocimetry) measurement at three spaces of plates for 5, 10 and 15 mm with variation of inlet flow rates of $0.25m^3$/h and $0.5m^3$/h. The experimental results showed that the space of the plates acts a significant role in the separating process.

• 한국컴퓨터정보학회논문지
• /
• 제23권4호
• /
• pp.57-64
• /
• 2018

In this paper, we propose the automatic detection method for individual region separation using panorama image. Finding areas that contain individual teeth is one of the most important tasks in automating 3D models through individual tooth separation. In the conventional method, the maxillary and mandibular teeth regions are separated using a straight line or a specific CT slide, and the tooth regions are separated using a straight line in the vertical direction. In the conventional method, since the teeth are arranged in a curved shape, there is a problem that each tooth region is incorrectly detected in order to generate an accurate tooth region. This is a major obstacle to automating the creation of individual tooth models. In this study, we propose a method to find the correct tooth curve by using the jawbone curve which is very similar to the tooth curve in order to overcome the problem of finding the area containing the existing tooth. We have proposed a new method to accurately set individual tooth regions using the feature that individual teeth are arranged in a direction similar to the normal direction of the tooth alignment curve. In the proposed method, the maxillary and mandibular teeth can be more precisely separated than the conventional method, and the area including the individual teeth can be accurately set. Experiments using real dental CT images demonstrate the superiority of the proposed method.

• 한국음향학회지
• /
• 제31권5호
• /
• pp.332-339
• /
• 2012

빔공간 변환(beamspace transform) 기법은 공간 영역의 신호를 입사각 혹은 그 사인함수의 영역으로 변환하는 기법으로, MUSIC과 같은 음원 정위 및 추적(source localization and tracking) 문제나 적응 빔형성(adaptive beamforming)과 같은 문제에서 많이 사용되는 기법이다. 다채널 음원 분리 기법에 사용될 때에는, 음원의 정보 뿐만아니라 해당 음원의 이미지(image)를 재구성하여야 하므로 역변환 기법 또한 중요하다. 본 논문에서는 멀티 채널 음원 분리 기법을 위한 빔공간 변환 기법과 그 역변환 기법에 대하여 고찰하였으며, 특히 빔공간-영역 다채널 비음수 행렬 분해 기법에 적용되었을 때 그 성능에 미치는 영향을 중점적으로 살펴보았다.

• 동력기계공학회지
• /
• 제4권4호
• /
• pp.78-83
• /
• 2000

It is often necessary to observe the working environment of a robot to control it efficiently in the remote location. The remote sensing data and control commands are transmitted via various media such as radio, microwave, and computer network. The World Wide Web can be used as the infrastructure for teleoperation of mobile robots. In this paper we propose an advanced technique of the remote control of mobile robots on the web. For the real-time control, the image separation algorithm is proposed to transmit the current positions of mobile robots instead of transmitting the full frame image. It is shown by experiments that the proposed algorithm is effective.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2005년도 춘계학술대회 논문집
• /
• pp.252-257
• /
• 2005

Injection molding is a very important industrial process for the manufacturing of plastics objects. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation' orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of weld-line in injection-molded products is assessed. And the effects of fiber content and injection mold-gate conditions on the fiber orientation are also discussed.

• 사물인터넷융복합논문지
• /
• 제6권2호
• /
• pp.37-43
• /
• 2020

본 논문은 스크린과 레이저 발사장치의 이격거리 변화에도 복수 개의 레이저 영상을 안정적으로 인식할 수 있는 최근접 각도 계산 방법을 제안하였다. 이 방법은 레이저 패턴 각도의 거리를 이용하여 사로를 인식하는 방법으로 레이저의 각도 추출은 레이블링 알고리즘을 이용하여 획득된 영상으로부터 레이저 영상을 검출하고, 허프 변환을 수행하여 직선의 각도를 추출한다. 유사성 척도 중 유클리드 거리를 이용하여 추출한 레이저 영상의 각도와 기준 각도의 거리를 계산하고, 계산된 거리 결과값을 이용하여 사로를 인식한다. 이격 거리를 "200cm~400cm"로 변경하면서 실험한 결과, 모든 이격 거리에서 개별 사로를 100% 인식했다. 실험을 통해 제안한 방법의 신뢰성을 확인하였다.

• 한국측량학회지
• /
• 제15권1호
• /
• pp.41-50
• /
• 1997

본 연구에서는 실시간에 걸쳐서, 자동적으로 공액점들을 매칭시킬 수 있는 색상분리기법을 제시하는데 목적을 두고 있다 CCD카메라에의해 취득된 영상으로부터 계산된 상좌표는 취득된 상좌표의 정확도 와 소트를 통한 매칭의 정확도 측면에서 점검되었다. 점검결과, 연구에의하여 취득된 상좌표를 이용하여 사진측량 프로그램에 의해 계산된 대상물좌표의 RMSE는 근거리사진측량의 기대RMSE내에 분포하고 있었으며, 소트에의한 공액표정점들의 매칭 또한 정확하게 수행되었다. 따라서 본 연구에서 제시하는 색상분리기법이 정확한 상좌표의 취득과 공액점의 매칭에 적절함을 알 수 있었으며, 이 방법은 실시간에 걸쳐서 취득정보를 빠르고 정확하게 처리해야하는 산업분야에 유용할 것으로 생각된다.