• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2594-2600
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• 2020

A gamma camera system using radionuclide has a functional imaging technique and is frequently used in the field of nuclear medicine. In the gamma camera, it is extremely important to improve the image quality to ensure accurate detection of diseases. In this study, we designed a blind-deconvolution framework after a noise-reduction algorithm based on a non-local mean, which has been shown to outperform conventional methodologies with regard to the gamma camera system. For this purpose, we performed a simulation using the Monte Carlo method and conducted an experiment. The image performance was evaluated by visual assessment and according to the intensity profile, and a quantitative evaluation using a normalized noise-power spectrum was performed on the acquired image and the blind-deconvolution image after noise reduction. The result indicates an improvement in image performance for gamma camera images when our proposed algorithm is used.

• 센서학회지
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• 제21권2호
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• pp.96-102
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• 2012

This paper addresses photometric distortion problems of a compact 3D scanning sensor which is composed of a micro-size and inexpensive camera-projector system. Recently, many micro-size cameras and projectors are available. However, erroneous 3D scanning results may arise due to the poor and nonlinear photometric properties of the sensors. This paper solves two inherent photometric distortions of the sensors. First, the response functions of both the camera and projector are derived from the least squares solutions of passive and active calibration, respectively. Second, vignetting correction of the vision camera is done by using a conventional method, however the projector vignetting is corrected by using the planar homography between the image planes of the projector and camera, respectively. Experimental results show that the proposed technique enhances the linear properties of the phase patterns that are generated by the sensor.

• 방송공학회논문지
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• 제11권4호
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• pp.495-506
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• 2006

본 논문에서는 실감 콘텐츠 생성에 쓰이는 움직이는 다수 카메라 시스템을 위한 분해법 기반 자동 보정 알고리즘을 제안한다. 대부분의 기존 자동 보정 연구는 스테레오 카메라 혹은 고정된 다수 카메라 시스템에 한정되어왔다. 보다 넓은 영역의 3차원 복원이나, 다수 카메라를 사용하는 일반적인 응용으로의 확장을 위해서는 새로운 알고리즘에 대한 연구가 필요하다. 본 논문에서는 일반적인 다수 카메라 시스템 (동적인 시스템 포함) 구조에 대한 강건한 자동 보정 방법을 제안하고, 카메라 구조가 평면 구성을 갖는 다수 카메라 시스템 보정 알고리즘을 제안한다. 우선, 기하학적 제한 요소를 바탕으로 분해법을 사용하기 위한 수식을 유도하고, 유도된 정리를 바탕으로 실질적인 자동 보정 사용법을 설명한다. 특히, 평면을 이루는 카메라 시스템에서의 분해법 적용이 어파인 복원과 같다는 성질을 증명하고, 어파인 분해법을 활용한 자동 보정 알고리즘을 제시한다. 실험에서는 제안된 알고리즘을 시뮬레이션 데이터와 실제 영상에 적용한 실험 결과를 보인다. 제안된 알고리즘은 다수 카메라 시스템을 활용한 영상 기반 3차원 실감 콘텐츠 복원이나, 하드웨어의 지원과 함께 실시간 다수 카메라 증강 현실 시스템에 활용될 수 있다.

• 한국의학물리학회지:의학물리
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• 제26권1호
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• pp.18-27
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• 2015

컴프턴 산란 현상을 이용하여 전자적 집속 방법으로 영상화하는 컴프턴카메라는 고민감도 및 고에너지 해상도의 장점을 이용하여 핵의학 응용분야에 대한 잠재력이 큰 영상 시스템이다. 본 논문에서는 컴프턴카메라를 이용한 다중 추적자 영상의 효용성 평가와 정확한 3차원 단면영상 촬영을 위한 Orlov 조건을 만족하는 회전하는 컴프턴카메라의 구조를 조사하였다. 140/511 keV의 방사선원의 소프트웨어 모형을 구성하고 이에 대한 몬테카를로 전산모사 시뮬레이션을 수행하여 리스트모드 배열된 부분집합 기댓값 최대화 방법으로 재구성된 다중 추적자 영상으로 컴프턴카메라의 효용성을 검증하였다. 산란부와 흡수부를 평행하게 위치시킨 고정된 컴프턴카메라와 촬영대상 주위 $360^{\circ}$를 회전하는 컴프턴카메라를 구성하여 검출된 투사선의 구좌표계 각도에 대한 히스토그램을 비교 평가하였다. 140/511 keV의 동시 계측된 몬테카를로 전산모사 데이터의 다중 추적자 영상이 2차원 및 3차원 재구성 시 잘 구분되는 것을 확인하였으며, 회전된 컴프턴카메라의 경우, 회전각도에 반비례하여 3차원 영상재구성에 필요한 유효 투사선이 증가하였다. 26분의 계산 시간 및 5백만개의 적절한 유효 투사선의 개수를 고려할 때 컴프턴카메라의 회전각은 $30^{\circ}$가 현실적으로 적절할 것이며 증가한 검출 시간은 다중 컴프턴카메라를 구성하여 해결할 수 있다. 본 논문에서 고찰한 고민감도 및 고에너지 해상도를 가진 컴프턴 카메라는 다중추적자 영상화를 위해 적합한 시스템이며 생화학 및 생리학적 상태 변화에 대한 임상 정보를 제공하며 각종 질병 진단 및 치료 방법 개발 등에 기여할 수 있는 잠재력이 있는 영상 시스템이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.151-152
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• 2009

• 제어로봇시스템학회논문지
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• 제17권3호
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• pp.229-235
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• 2011

To make a robust object tracking and identifying system for an intelligent robot and/or home system, heterogeneous sensor fusion between visible ray system and infrared ray system is proposed. The proposed system separates the object by combining the ROI (Region of Interest) estimated from two different images based on a heterogeneous sensor that consolidates the ordinary CCD camera and the IR (Infrared) camera. Human's body and face are detected in both images by using different algorithms, such as histogram, optical-flow, skin-color model and Haar model. Also the pose of human body is estimated from the result of body detection in IR image by using PCA algorithm along with AdaBoost algorithm. Then, the results from each detection algorithm are fused to extract the best detection result. To verify the heterogeneous sensor fusion system, few experiments were done in various environments. From the experimental results, the system seems to have good tracking and identification performance regardless of the environmental changes. The application area of the proposed system is not limited to robot or home system but the surveillance system and military system.

• 전기학회논문지
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• 제64권6호
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• pp.912-921
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• 2015

In this paper, we introduce fuzzy inference-based real-time deterioration diagnosis system with the aid of infrared thermal imaging camera. In the proposed system, the infrared thermal imaging camera monitors diagnostic field in real time and then checks state of deterioration at the same time. Temperature and variation of temperature obtained from the infrared thermal imaging camera variation are used as input variables. In addition to perform more efficient diagnosis, fuzzy inference algorithm is applied to the proposed system, and fuzzy rule is defined by If-then form and is expressed as lookup-table. While triangular membership function is used to estimate fuzzy set of input variables, that of output variable has singleton membership function. At last, state of deterioration in the present is determined based on output obtained through defuzzification. Experimental data acquired from deterioration generator and electric machinery are used in order to evaluate performance of the proposed system. And simulator is realized in order to confirm real-time state of diagnostic field

• 천문학회보
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• 제35권2호
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• pp.62.1-62.1
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• 2010

CQUEAN (Camera for QUasars in EArly uNiverse) is an optical CCD camera system that consists of a science CCD camera, a guide CCD camera, and seven filters. In addition, a focal reducer is installed in front of the science camera to secure a larger field of view for the system. Engineering run of the system was carried out from Aug. 10, 2010 to Aug. 17, 2010, with 2.1m Otto Struve telescope at McDonald Observatory, USA, from which we investigated the characteristics and performance of the system. Bias and dark images were taken under various temperature conditions to examine the system behavior, and both twilight and dome flat images were obtained to investigate the appropriate preprocessing procedures of the data. Crude initial estimate indicated one hour integration would reach limiting magnitude of 24.2 in i-band with S/N ratio of 5, with CQUEAN at 2.1m telescope. The detailed results of the engineering run will be presented.

• 한국생산제조학회지
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• 제26권2호
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• pp.223-229
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• 2017

Recently, robotic bin-picking tasks have drawn considerable attention, because flexibility is required in robotic assembly tasks. Generally, stereo camera systems have been used widely for robotic bin-picking, but these have two limitations: First, computational burden for solving correspondence problem on stereo images increases calculation time. Second, errors in image processing and camera calibration reduce accuracy. Moreover, the errors in robot kinematic parameters directly affect robot gripping. In this paper, we propose a method of correcting the bin-picking error by using trinocular vision system which consists of two stereo cameras andone hand-eye camera. First, the two stereo cameras, with wide viewing angle, measure object's pose roughly. Then, the 3rd hand-eye camera approaches the object, and corrects the previous measurement of the stereo camera system. Experimental results show usefulness of the proposed method.

• 센서학회지
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• 제27권1호
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• pp.6-12
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• 2018

In this paper, a 32-variable pulse position modulation (32-VPPM) scheme is proposed to support a red-green-blue light-emitting-diode (RGB-LED)-based optical camera communication (OCC) system. Our proposed modulation scheme is designed to enhance the OCC data transmission rate, which is targeted for the wearable biomedical data monitoring system. The OCC technology has been utilized as an alternative solution to the radio frequency (RF) wireless system for long-term self-healthcare monitoring. Different biomedical signals, such as electrocardiograms, photoplethysmograms, and respiration signals are being monitored and transmitted wirelessly from the wearable biomedical device to the smartphone receiver. A common 30 frames per second (fps) smartphone camera with a CMOS image sensor is used to record a transmitted optical signal. Moreover, the overall proposed system architecture, modulation scheme, and data demodulation are discussed in this paper. The experimental result shows that the proposed system is able to achieve > 9 kbps using only a common smartphone camera receiver.