• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.933-934
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• 2006

High level perceptual tasks such as context understanding, SLAM and object recognition are essential for intelligent robot to provide services for human supports. Those intelligent robots often use camera sensor for vision information, sonar or laser sensor for range information, encoder for angular velocity of wheel and so on. The information is generated at different time intervals by the different H/W devices and S/W algorithms. The generation of high level information requires the specific mixture of low level information. And the information should be represented to be useful for robots to use in their ecological niche. In conventional robot systems, perceptual module requires the resource to use by tightly coupling whenever it is needed. So the resource and information cannot be easily shared and even could be invalid for the delayed information. In this paper, we propose a synchronization system of robot-centered information for context understanding. Our system represents information for the robot capacity and synchronizes the information that is asynchronously generated, where is employed the black-board architecture.

• 제어로봇시스템학회논문지
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• 제15권5호
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• pp.519-524
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• 2009

This paper describes a new sensor system for 3D environment perception using stereo structured infrared light sources and a camera. Environment and obstacle sensing is the key issue for mobile robot localization and navigation. Laser scanners and infrared scanners cover $180^{\circ}$ and are accurate but too expensive. Those sensors use rotating light beams so that the range measurements are constrained on a plane. 3D measurements are much more useful in many ways for obstacle detection, map building and localization. Stereo vision is very common way of getting the depth information of 3D environment. However, it requires that the correspondence should be clearly identified and it also heavily depends on the light condition of the environment. Instead of using stereo camera, monocular camera and two projected infrared light sources are used in order to reduce the effects of the ambient light while getting 3D depth map. Modeling of the projected light pattern enabled precise estimation of the range. Two successive captures of the image with left and right infrared light projection provide several benefits, which include wider area of depth measurement, higher spatial resolution and the visibility perception.

• 대한전자공학회논문지SD
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• 제40권8호
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• pp.589-597
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• 2003

비쥬얼 크립토그래피는 암호법에서 중요한 정보를 암호화하여 복수 회원에게 분산시킨 후 회원의 합의에 의하여 해독이 가능하게 하는 thresholding scheme을 디지털 시스템인 아닌 인간의 시각 시스템으로 해독이 가능하게 하였다. 그러나 표현의 한계로 인하여 몇 가지 문제점을 지니고 있었다. 이후 인간의 시각을 대신하여 레이져를 사용하는 광 비쥬얼 크립토그래피가 제안되어 광학 시스템에 암호법을 적용할 수 있게 되었다. 그러나 이 시스템은 기존의 비쥬얼 크립토그래피의 문제점을 완전히 극복하지 못함으로 인하여 또 다른 문제를 발생하였다. 이 것은 데이터 처리 시스템을 시각에서 광학으로 전환하는 과정에서 발생하였으므로 문제의 분석과 해결 역시 광학적으로 접근하는 것이 타당하다. 본 논문에서는 joint transform correlator를 이용하여 광 비쥬얼 크립토그래피에서 발생하는 잡음의 정도와 안정성을 주파수 관점에서 분석하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권2호
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• pp.85-92
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• 2003

In this paper, we propose a method to evaluate performances of mobile personal robots. A set of performance measures is proposed and the corresponding evaluation methods are developed. Different from industrial manipulators, personal robots need to be evaluated with its mobility, navigation, task and intelligent performance in environments where human beings exist. The proposed performance measures are composed of measures for mobility including vibration, repeatability, path accuracy and so on, as well as measures for navigation performance including wall following, overcoming doorsill, obstacle avoidance and localization. But task and intelligent behavior performances such as cleaning capability and high-level decision-making are not considered in this paper. To measure the proposed performances through a series of tests, we designed a test environment and developed measurement systems including a 3D Laser tracking system, a vision monitoring system and a vibration measurement system. We measured the proposed performances with a mobile robot to show the result as an example. The developed systems, which are installed at Korea Agency for Technology and Standards, are going to be used for many robot companies in Korea.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2003년도 춘계학술발표논문집 (상)
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• pp.409-412
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• 2003

The 3-D shape use to effect of movie, animation, industrial design, medical treatment service, education, engineering etc... But it is not easy to make 3-D shape from the information of 2-D image. There are two methods in restoring 3-D video image through 2-D image; First the method of using a laser; Second, the method of acquiring 3-D image through stereo vision. Instead of doing two methods with many difficulties, I study the method of simple 3-D image in this research paper. We present here a simple and efficient method, called direct calibration, which does not require any equations at all. The direct calibration procedure builds a lookup table(LUT) linking image and 3-D coordinates by a real 3-D triangulation system. The LUT is built by measuring the image coordinates of a grid of known 3-D points, and recording both image and world coordinates for each point; the depth values of all other visible points are obtained by interpolation.

• 센서학회지
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• 제14권2호
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• pp.116-124
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• 2005

In this paper range measurement systems are designed using an ultrasonic sensor and a camera. An ultrasonic sensor provides the range measurement to a target quickly and simply but its low resolution is a disadvantage. We tackle this problem by employing a camera. Instead using a stereoscopic sensor, which is widely used for 3D sensing but requires a computationally intensive stereo matching, the range is measured by focusing and structured lighting. In focusing a straightforward focusing measure named as MMDH(min-max difference in histogram) is proposed and compared with existing techniques. In the method of structure lighting, light stripes projected by a beam projector are used. Compared to those using a laser beam projector, the designed system can be constructed easily in a low-budget. The system equation is derived by analysing the sensor geometry. A sensing scenario using the systems designed is in two steps. First, when better accuracy is required, measurements by ultrasonic sensing and focusing of a camera are fused by MLE(maximum likelihood estimation). Second, when the target is in a range of particular interest, a range map of the target scene is obtained by using structured lighting technique. The systems designed showed measurement accuracy up to 0.3[mm] approximately in experiments.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.543-544
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• 2006

This paper describes a simple real-time monitoring system for use in measurement subsystem of contact wire and geometry of overhead contact wire in electric railway. The system has been consists of a high speed CMOS camera with resolution $1024\;{\times}\;1280$ pixels, line type laser source with a power equal to 300 mW, and PC-based image acquisition system with PCI Express slot. National instrument LabVIEW (8.0) and vision acquisition software have been used in application programming interface for image acquisition, display, and storage with a frequency of sampling of 500 acquisitions per second.

• International Journal of Korean Welding Society
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• 제2권2호
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• pp.51-56
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• 2002

The weld seam tracking system for arc welding process uses various kinds of sensors such as arc sensor, vision sensor, laser displacement sensor and so on. Among the variety of sensors available, electro-magnetic sensor is one of the most useful methods especially in sheet metal butt-joint arc welding, primarily because it is hardly affected by the intense arc light and fume generated during the welding process, and also by the surface condition of weldments. In this study, a dual-electromagnetic sensor, which utilizes the induced current variation in the sensing coil due to the eddy current variation of the metal near the sensor, was developed for arc welding of sheet metal I-butt joints. The dual-electromagnetic sensor thus detects the offset displacement of weld line from the center of sensor head even though there's no clearance in the joint. A set of design variables of the sensor was determined far the maximum sensing capability through the repeated experiments. Seam tracking is performed by correcting the position of sensor to the amount of offset displacement every sampling period. From the experimental results, the developed sensor showed the excellent capability of weld seam detection when the sensor to workpiece distance is near less than 5 ㎜, and it was revealed that the system has excellent seam tracking ability for the I-butt joint of sheet metal.

• 대한시과학회지
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• 제20권4호
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• pp.443-451
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• 2018

목적 : 레이저 각막교정술을 받은 후 자동굴절검사기기의 신뢰성에 대해 알아보고자 한다. 방법 : LASEK 수술 최소 3개월 후 나안 시력이 1.0인 57명(114안, $32.0{\pm}26.91$세) 대상자의 굴절상태를 자동굴절검사기(CANON Full Auto Ref-Keratometer RK-F1, Japan)과 검영기(Streak Retinoscope 18200, WelchAllyn, USA)을 이용하여 구면과 실린더굴절력을 측정하였고, 등가구면굴절력과 함께 비교하였다. 수술 전의 굴절상태를 자동굴절검사기기를 이용하여 측정한 결과에 따라 고도, 중도, 저도 근시로 나누어 다시 비교하여 수술 전 굴절상태에 따른 수술 후 자동굴절검사기의 신뢰성의 영향을 분석하였다. 두 타각적굴절방법을 Bland-Altman(Bland-Altman limits of agreement(LoA))을 이용하여 두 방법의 일치도를 확인하였다. 결과 : 수술 후 자동굴절검사법과 검영법에 의한 구면, 실린더, 등가구면굴절력은 전체 비교에서는 모두 통계적으로 유의한 차이(p<0.01)를 보였으며, 수술 전의 굴절상태 분류로서 고도 근시의 실린더굴절력을 제외한 중도, 저도 근시의 모든 요소에서 유의한 차이(p<0.01)를 보였다. 전체적으로 자동굴절검사법에 의한 굴절력은 특히 구면과 등가구면굴절력에서 0.38D ~ 0.53D의 근시 경향으로 나타났다. 반면 검영법은 평균 약 0.30D의 원시 경향을 보였다. 두 굴절검사법의 비교에서는 평균은 $-0.51{\pm}0.45D$, LoA는 +0.36D ~ -1.39D로 나타나 근시 경향이 강하였으며, 호환성이 있는 것으로 나타났다. 결론 : 호환성 측면에서는 긍정적이지만, 레이저 각막교정수술 후의 근시 퇴행이 있는 수술자들의 자동굴절검사법은 근시 경향을 보이기 때문에 반드시 자각적굴절검사를 통해 안경처방을 해야 할 것으로 보인다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권7호
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• pp.87-94
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• 2019

최근 구조물 계측분야에서 구조물의 동적 변위응답 측정에 관한 연구가 주목을 받고 있다. 본 연구는 이와 같은 동적 변위데이터의 활용도를 넓히고자 구조안전도 평가를 위한 방법론 제시를 목표로, 동적 변위데이터를 활용하여 부공간 시스템 식별법이 적용된 구조물 물리량 추정기법을 개발하였다. 진동 변위 데이터로부터의 상태공간모델을 추정하기 위한 부공간 시스템 식별 이론과 시스템의 물리량을 도출하기 위한 물리해석 기법을 제시하였고 실험적 검증을 위해 동적 실험을 수행하였다. 3자유도 철골 구조물을 제작하여 진동대를 활용해 지반 가진하여 각 층의 변위 데이터와 진동대의 가속도 데이터를 계측하였다. 계측된 데이터를 활용해 이산화 된 상태공간모델을 생성하였고 정밀도 파악을 위해 상태공간방정식을 통한 전산 해석을 수행하였으며, 철제 구조물의 상태공간모델로부터 층강성을 추출하였다. 또한 상태공간모델로부터 추출된 층강성을 기준으로 5가지의 기둥강성 보강 및 손상 시나리오를 설정하여 매 시나리오별 층강성 변화율을 추출하였으며 동일한 조건의 보강 및 손상의 경우, 강성 변화가 높은 일치율을 보이는 것을 확인하였다.