• 제어로봇시스템학회논문지
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• 제14권1호
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• pp.75-80
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• 2008

This paper presents a vision based autonomous inspection system for welding quality control of a RV sinking seat. In order to overcome the precision error that arises from a visible inspection by an operator in the manufacturing process of a RV sinking seat, the machine vision based welding quality control system is proposed. It consists of the CMOS camera and the NI vision system. The geometry of the welding bead, which is the welding quality criteria, is measured by using the captured image with a median filter applied on it. The image processing software for the system was developed using the NI LabVIEW software. The proposed welding quality inspection system for RV sinking seat was verified using experimentation.

• 한국분무공학회지
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• 제21권1호
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• pp.13-19
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• 2016

Atmospheric spray characteristics were experimentally compared between liquid-gas and liquid-liquid sprays of a pintle injector. In order to study spray characteristics, water and air were used as the simulants and the visualization technic was adopted. Spray images were acquired by using a backlight method by a high-resolution CMOS camera. As a result, when the pintle opening distance increased, liquid sheets became unstabled and fluttering droplets increased. In the liquid-gas case, the breakup performance increased as the pressure of gas injected from the annular orifice increased. In the liquid-liquid case, atomization efficiency decreased as the pressure of liquid injected from the annular orifice increased. Spray angles presented a similar trend between two cases. At the same momentum ratio, the spray angle of liquid-liquid case was lower than the angle of liquid-gas case.

• Journal of the Optical Society of Korea
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• 제13권4호
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• pp.464-467
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• 2009

The grating projection method with phase-shifting technique is very useful in measuring the 3-dimensional (3D) shape with high accuracy and speed. In this work, we have developed an ultra high-speed digital laser grating projection system using a high-power laser diode and a highsensitivity CMOS camera. With our system, the optical measurement required to find out the profile of a 3D object could be carried out within 2.6 ms, which is a significant ($\sim$10 times) improvement compared with those of the previous studies.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.900-904
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• 2009

The measurement of contact wire uplift in electric railway is one of the most test method to accept the maximum permitted speed of new vehicles or pantographs. The contact wire uplift can be measured for shot periods when pantograph is running in monitoring station. This paper describes the development of two different methods for contact uplift measurement using vision-based system and wireless online monitoring system. Our vision-based system employs a high-speed CMOS (Complementary Metal Oxide Semiconductor) camera with gigabit ethernet LAN. The development of a real-time remote monitoring system that acquires data from any kind of sensor to be transmitted by wireless communication from overhead line and structure at 25 kV to a computer in catenary system. The proposed two kind of different measurement systems to evaluation for dynamic uplift of overhead contact wire shows promising on-field applications for high speed train such as Korea Tilting Train (TTX) and Korea Train eXpress (KTX).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.408-410
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• 2009

First demonstrators of bi-directional OLED microdisplay devices have been developed and integrated into see-through HMD optics. The device combines 'display' and 'imaging' by nested OLED pixels and photodetectors in a single CMOS chip. Major aim of this integration is to provide capabilities for eyetracking to achieve gaze-based human-displayinteraction.

• 한국분무공학회지
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• 제17권1호
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• pp.9-13
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• 2012

This study investigates experimentally evaporation characteristics of nanofluid droplets containing 50 nm alumina($Al_2O_3$) particles and the wettability changes on a hydrophilic glass surfaces. From the captured digital images by using a CMOS camera and a magnifying lens, we examined the effect of particle concentration on droplet evaporation rate which can be indirectly deduced from the measured droplet volumes varying with time. In particular, with the use of a digital image analysis technique, the present study measured droplet perimeters and the contact angles to study the wetting dynamics during evaporating process. In addition, we compared the measured total evaporation time with theoretically estimated values. It was found that as the volume fractions of nanofluid increased, the total evaporation time and the initial contact angles decreased, while the droplet perimeters increased.

• 한국항해항만학회지
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• 제35권2호
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• pp.131-136
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• 2011

As the faithful performance of ISPS of IMO, nowadays actually applicable an integrated safety and security system in and out of vessel should be organized in views of seafarers. Therefore, this paper is aimed to design a fundamental system for ship's integrated safety and security. The system of integrated grabbing will affect efficiently in any maritime field of material and human flow. Therefore this research will be expected to affect economical side by securing all the risk of maritime issues. In addition to the passenger ship and merchant vessel, it is applicable to other public and private vessels either. As a result of this paper, the system designed collecting various data through integrating the system including RFID reader, PIR sensor, and CMOS camera by putting an individual number into each unit that could be control at easy.

• 천문학회보
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• 제45권1호
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• pp.67.1-67.1
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• 2020

Adaptive Optics (AO) is the technology for ground-based telescopes to overcome the interference caused by atmospheric turbulence. We are developing an AO system for the 1-m telescope at Seoul National University Observatory (SNUO). The seeing size of the SNUO is 2 arcseconds on average, and 0.85 arcseconds at best condition. Our system is based on MEMS deformable mirror and Shack-Hartmann wavefront sensor. We developed the wavefront sensor using a cheap CMOS camera, and measured phase disturbance at SNUO. To verify the performance of the AO system, we designed an artificial phase disturber that produces similar scale phase error, measured at SNUO. We carried out laboratory tests in which the AO system measures and corrects the wavefront using the phase disturber and an F/6 light source, the same as that of SNUO telescope. The control system was developed in C++. The system performs closed-loop PI correction up to 100 Hz at a consumer-grade PC.

• 한국멀티미디어학회논문지
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• 제13권5호
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• pp.641-650
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• 2010

컬러 이미지 센서는 광전 변환을 일으키는 촬상 소자와 내부의 영상처리 과정을 거쳐서 컬러 이미지를 출력한다. 일반적으로 출력 영상은 원 피사체의 XYZ 3 자극치와 카메라 RGB 출력 신호 사이의 변환 관계인 카메라 전달 특성에 의해 결정된다. 본 논문에서는 컬러 이미지 센서의 내부 조정 항목인 노출-증폭-레벨(shutter-gain-level, SGL)의 특성함수와 자동 화이트 밸런스 상태를 이용한 카메라 전달 행렬을 이용하여 영상의 colorimetry(측색) 상태를 분석하는 기법을 제안한다. 제안 방법으로부터 실제 영상물의 색도와 휘도 등을 예측할 수 있다. 연구에 사용된 컬러 이미지 센서의 AE(auto exposure) 상태와 실제 휘도의 관계를 정량화하여 SGL 함수를 유도하여 영상의 휘도를 예측 한다. 그리고 영상의 색도는 최소 제곱 다항식 모델링 (polynomial modeling)을 이용하여 기준 환경에서 얻은 카메라 전달 행렬과 AWB(auto white balance) 상태를 통해 예측한다. 실험을 통해서 컬러 이미지 센서를 이용한 제안된 영상의 색도와 휘도 예측 기법의 성능이 우수함을 볼 수 있고, 예측된 결과는 실제 영상물 계측과 시청 환경 측정을 이용한 디스플레이 화질 설정 시스템, 보안 등의 다양한 분야에서 응용이 가능하다.

• 한국측량학회지
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• 제35권6호
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• pp.563-572
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• 2017

본 연구의 목적은 회전익 UAV를 이용하여 1cm 미만의 GSD를 갖는 초고해상도 영상을 취득하기 위해 비행고도, 비행속도, 카메라 셔터의 노출시간, 자동초점조절 사용 여부가 영상의 시각적 해상도에 미치는 영향을 객관적으로 분석하는 것이다. 아울러 다양한 형태의 항공표적에 대한 인식 용이성을 평가하는 것도 목표로 한다. 이를 위해 35mm 크기의 7952*5304 화소 CMOS 센서와 55mm 단렌즈를 이용하여 비행고도 20m부터 120m에서 20m 간격으로 촬영하고 영상의 시각적 해상도를 분석하였다. 결과로 자동초점조절을 사용한 경우 시각적 해상도는 이론적인 GSD에 비하여 1.1~1.6배로 나타났고, 자동초점조절을 사용하지 않은 경우 1.5~3.5배로 나타났다. 다음으로 비행고도 80m에서 5m/s로 정속 비행하면서 카메라의 노출 시간을 1/60sec에서 1/2000sec까지 1/2씩 줄이면서 촬영하고 시각적 해상도를 분석하였다. 허용 흐려짐을 1 화소로 가정할 때 최장 노출 시간을 준수한 경우 시각적 해상도 는 이론적인 GSD이 비하여 1.3~1.5배로 나타났고, 초과한 경우 1.4~3.0배로 나타났다. A4 용지에 항공표적을 출력하여 비행고도 80m 이내에서 촬영하면 상용소프트웨어를 이용하여 코드화된 항공표적을 자동으로 인식할 수 있으며, 자동 인식이 불가능한 고도에서도 다양한 형태의 일반 항공표적 및 코드화된 항공표적을 큰 어려움 없이 수동으로 인식할 수 있었다.