• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.518-519
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• 2016

AOI 검사기는 SMT 공정 상에서 PCB (printed Circuit Board) 상의 부품들을 카메라로 촬영하고 촬영된 영상을 2D 혹은 3D 형태의 이미지로 재구성하고 분석하여 이상 여무를 판단하는 장비다. 검사를 하고자 하는 PCB의 크기가 카메라가 촬영할 수 있는 영역 보다 큰 경우가 대부분이기 때문에 PCB 상에 마운트 되어 있는 부품들을 모두 촬영하기 위해서는 여러 차례 나누어 촬영해야 할 필요가 있으며 이 때문에 PCB 상에 촬영해야 하는 부품들을 가능한 FOV에 많이 포함될 수 있도록 여러 FOV 영역으로 나누고 이렇게 나누어진 FOV 영역들을 최적의 경로로 이동하며 촬영할 수 있도록 하기 위한 알고리즘이 필요하다. 기존 논문들은 대부분 이 문제를 해결하기 위한 알고리즘에 대해 다루어 왔다. 일반적으로 생산이 진행되는 시점에서는 검사해야 할 PCB에 대한 정보 (PCB의 크기, 부품의 위치, 크기, 종류 등)는 이미 정해져 있기 때문에 경로 계획 최적화 수행은 PCB 정보에 변동이 없다면 한차례만 하면 된다. 하지만 검사를 할 수 있도록 Teaching 하는 단계에서는 PCB 정보가 지속적으로 변경될 수 있으며 이에 따라 최적화를 여러 차례 수행해야 할 필요성이 있다. 최적화를 위한 처리 시간은 부품의 개수, PCB 상에서의 분포정도등에 따라 증가하기 때문에 PCB 정보가 변경될 때 마다 최적화를 수행하게 되면 비효율적으로 처리 시간이 증가하게 된다. 본 논문에서는 이 문제에 대해 연구하고 해결책을 제시하였다.

• Laser Solutions
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• v.14 no.2
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• pp.24-29
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• 2011

The design of a telecentric f-${\theta}$ lens with a field of view (FOV) $30^{\circ}$ and an effective focal length of 1000mm is presented. The optical stop is placed at the front plane and the design is based on a geometric ray tracing technique, and the designed system consists of a series of convex and concave lenses. The designed f-${\theta}$ lens showed a considerable reduction in weight with a simplified structure and resulted in a good performance in the designated FOV. Detail analysis of rays is also presented. 653nm (red laser), 586nm (green laser), and 468nm (blue laser) were simulated as a light source and image illuminating source. The developed optical design requires 7 pieces of lenses made of SF1, N-FK56, N-LAK33, and BK7 glass materials. With optimal parametric design, the effective focal length was calculated to be 974.839mm which is very close to the initial design target. For the manufacturing purpose, the dimensions of lens curvature and thickness were truncated with error ranging 0.1% to 3.2%. As a result, the overall error was calculated to be 3.2% which can be still tolerable for display, laser material, and machining processing.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.87.1-87.1
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• 2011

Since early 90's, the solar X-ray telescopes such as Yohkoh SXT and Hinode XRT have observed coronal magnetic structures on the Sun's surface in the range of about $40'{\times}40'$ field-of-view (FOV) covering the full solar disk. Thus it has been stressed by the scientists that the optical structure of solar telescopes should be designed with care for improving the uniformity over a wide FOV. There would be, however, no unique solution in designing the optical system of a telescope for overcoming perfectly the problem of off-axis response variation. As a consequence, the correction of optical imperfectness of telescopes has become an important calibration step that should be performed beforehand when the observed images are to be used for photometric purposes. In particular, a special care should be taken when performing the temperature analysis with thin and thick filters for flaring activities observed at the periphery of the full FOV. From the analyses of both pre-launch calibration and in-flight observation data, the optical characteristics for describing the performance of solar X-ray telescopes, especially in view of their energy dependence, will be introduced and discussed in our presentation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1586-1594
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• 2011

LED-ID (light emitting diode - identification) technology is the new paradigm in the identification technology environment. LED-ID system typically needs line of sight (LOS) that supports narrow FOV transceivers links to achieve high data rate. On the other hand, narrow FOV reduces the coverage area. Therefore, the number of tags is increased significantly to cover the whole area. In this case number of link switching is increased when the reader moves within whole coverage area. Link switching delay is the important factor for the moving reader to maintain the communication with high data rate and better QoS. In this paper we propose in literature a new link switching scheme and measure the link switching delay time for LED-ID system. The simulation results show that the proposed link switching scheme is a possible candidate for multi-tag LED-ID system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.3023-3029
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• 2013

This is an example we generally have a variety of equipment that can detect and track the targets and track them quickly and accurately through the information exchange among each piece of equipment. These equipment have similar detection areas (FOV), but some are different due to the limit of the resolution of the equipment. In this paper, we studied the method of reducing detection time and tracking the targets automatically.

• Current Optics and Photonics
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• v.6 no.4
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• pp.392-399
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• 2022

Light-measuring devices (LMDs) are frequently used to measure luminance and color coordinates of displays. However, it is very difficult to use a conventional LMD for measuring the optical properties of virtual-reality (VR) devices with a wide field of view (FOV), because of their confined spaces where the entrance pupil of a LMD is located. In this paper, a new LMD that can measure the optical properties of wide-FOV VR devices, without physical conflict with the goggles of the VR device, is proposed. The LMD is designed to fully satisfy the requirements of IEC 63145-20-10, and a pivot-point correction method for the LMD is applied to improve its accuracy. To show the feasibility of the developed LMD and the correction method, seven VR devices with wide FOV are measured with it. From the results, all of them are successfully measured without any physical conflict, and a comparison to their nominal values shows that the FOVs have been properly measured.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.10-16
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• 2012

For high speed visual inspection in semiconductor industries, it is essential to acquire two-dimensional images on regions of interests with a large field of view (FOV) and a high resolution simultaneously. In this paper, an imaging system is newly proposed to achieve high quality image in terms of precision and FOV, which is composed of single lens, a beam splitter, two camera sensors, and stereo image grabbing board. For simultaneously acquired object images from two camera sensors, Zhang's camera calibration method is applied to calibrate each camera first of all. Secondly, to find a mathematical mapping function between two images acquired from different view cameras, the matching matrix from multiview camera geometry is calculated based on their image homography. Through the image homography, two images are finally registered to secure a large inspection FOV. Here the inspection system of using multiple images from multiple cameras need very fast processing unit for real-time image matching. For this purpose, parallel processing hardware and software are utilized, such as Compute Unified Device Architecture (CUDA). As a result, we can obtain a matched image from two separated images in real-time. Finally, the acquired homography is evaluated in term of accuracy through a series of experiments, and the obtained results shows the effectiveness of the proposed system and method.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2799-2805
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• 2024

Energy-resolved neutron imaging is an effective way to investigate the internal structure and residual stress of materials. Different sample sizes have varying requirements for the detector's imaging field of view (FOV) and spatial resolution. Therefore, a dual-mode energy-resolved neutron imaging detector was developed, which mainly consisted of a neutron scintillator screen, a mirror, imaging lenses, and a time-stamping optical fast camera. This detector could operate in a large FOV mode or a high spatial resolution mode. To evaluate the performance of the detector, the neutron wavelength spectra and the multiple spatial resolution tests were conducted at CSNS. The results demonstrated that the detector accurately measured the neutron wavelength spectra selected by a bandwidth chopper. The best spatial resolution was about 20 ㎛ in high spatial resolution mode after event reconstruction, and a FOV of 45.0 mm × 45.0 mm was obtained in large FOV mode. The feasibility was validated to change the spatial resolution and FOV by replacing the scintillator screen and adjusting the lens magnification.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.608-612
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• 2006

3 차원 공간상에서의 상호작용이란 특정 공간내의 오브젝트를 그 위치와 좌표축에 따라 조작하는 행위를 말한다. 이러한 3 차원 공간상의 상호작용을 행할 때 발생하는 가장 큰 문제중의 하나는 사용자가 현재 조작하고 있는 커서 또는 포인터의 깊이적 위치를 알기 힘들다는 점이며 흔히 깊이 지각문제(Depth Perception Problem)으로 불리 운다. 본 논문은 깊이 지각문제를 발생시키는 기본적인 요소중의 하나를 가상환경을 표현하기 위해 인공적으로 생성된 조망 절두체라고 고려하고 이에 대해서 논의한다. 이를 위하여 3 차원 입력 장치(SensAble PHANToM(R) OmniTM)를 이용한 간단한 위치지정 작업을 다양한 FOV(Field of View)와 VD(Viewing Direction)의 환경에서 피실험자들에게 수행하게 하였다. 결과적으로, 작업환경내의 FOV 변화는 작업수행의 정확도에 영향을 끼쳤으며, VD 의 경우, 사용자가 실제로 작업환경을 보는 것과 유사한 VD 환경이 효율성의 측면에서 보다 더 높은 작업수행 결과를 보였다.

• Journal of Korea Multimedia Society
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• v.23 no.8
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• pp.1088-1098
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• 2020

This paper proposes an obstacle avoidance method using a depth polar grid. Depth information is a crucial factor for determining the safe path for collision-free navigation of unmanned aerial vehicles (UAVs) as it can perceive the distance to the obstacles effectively. However, the existing depth-camera-based approaches for obstacle avoidance require computational y expensive path planning algorithms. We propose a simple navigation method using the polar-grid of the depth information obtained from the camera with narrow field-of-view(FOV). The effectiveness of the approach was validated by a series of experiments using software-in-the-loop simulation in a realistic outdoor environment. The experimental results show that the proposed approach successfully avoids obstacles using a single depth camera with limited FOV.