• 한국초전도ㆍ저온공학회논문지
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• 제15권3호
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• pp.13-19
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• 2013

Superconducting field coils using a high-temperature superconducting (HTS) wires with high current density generate high magnetic field of 2 to 5 [T] and electromagnetic force (Lorentz force) acting on the superconducting field coils also become a very strong from the point of view of a mechanical characteristics. Because mechanical stress caused by these powerful electromagnetic force is one of the factors which worsens the critical current performance and structural characteristics of HTS wire, the mechanical stress analysis should be performed when designing the superconducting field coils. In this paper, as part of structural design of superconducting field coils for 17 MW class superconducting ship propulsion motor, mechanical stress acting on the superconducting field coils was analyzed and structural safety was also determined by the coupling analysis system that is consists of commercial electromagnetic field analysis program and structural analysis program.

• 제어로봇시스템학회논문지
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• 제19권12호
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• pp.1089-1093
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• 2013

Depth extraction using the structured illumination method is popularly applied since it has the benefit of measuring the object without contact. With multiple spatial frequencies and phase-shifting techniques, it is possible to extract the depth of objects with large discontinuity. For applications such as 3D (Three Dimensional) displays, 3D information of the object is required and is useful if corresponding to each view of the display. For this purpose, hypercentric optics is appropriate to measure the depth information of an object with a large field of view that is applicable for a 3D display. By experiment, we present the feasibility for phase-shifting profilometry using hypercentric optics to obtain the depth information of an object with the field of view appropriate for a 3D display.

• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.162-168
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• 2007

For the past decade, the full-field digital mammography has been widely used for early diagnosis of breast cancer, and computer aided diagnosis has been developed to assist physicians as a second opinion. In this study, we try to predict the breast cancer using both mediolateral oblique(MLO) view and craniocaudal(CC) view together. A skilled radiologist selected 35 pairs of ROIs from both MLO view and CC view of digital mammogram. We extracted textural features using Spatial Grey Level Dependence matrix from each mammogram and evaluated the generalization performance of the classifier using Support Vector Machine. We compared the multi-view based classifier to single-view based classifier that is built from each mammogram view. The results represent that the multi-view based computer aided diagnosis in digital mammogram could improve the diagnostic performance and have good possibility for clinical use to assist physicians as a second opinion.

• 한국시뮬레이션학회논문지
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• 제19권1호
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• pp.23-31
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• 2010

180도 이상의 영역을 획득하는 어안렌즈(fisheye lens)는 최소의 카메라로 최대 시야각을 확보할 수 있는 장점으로 인해 차량 장착 시도가 늘고 있다. 이와 같이 어안렌즈를 통해 시야를 확보하고, 영상센서로 사용하기 위해서는 캘리브레이션 작업이 선행되어야 하며, 운전자에게 현실감 있는 영상을 제공하기 위해서는 이를 이용하여 방사왜곡(radial distortion)에 따른 기하학적인 왜곡 보정이 필요하다. 본 논문에서는 비대칭 왜곡을 가진 180도 이상 화각의 차량용 대각선 어안렌즈를 위해 영상 손실을 최소화하는 왜곡 보정 기법을 제안한다. 왜곡 보정은 왜곡 모델이 포함된 카메라 모델을 설정하고 캘리브레이션 과정을 통해 카메라 파라미터를 구한 후 왜곡이 보정된 뷰를 생성하는 과정으로 이루어진다. 먼저 왜곡모델로서 비선형의 왜곡 형상을 모방한 FOV(Field of View)모델을 사용한다. 또한 비대칭 왜곡렌즈의 경우 운전자의 좌우 시야각 확보에 중점을 두어 수직 화각보다 수평 화각이 크게 설계되었기 때문에 영상의 장축, 단축의 비율을 일치시킨 후 비선형 최적화 알고리즘을 사용하여 카메라 파라미터를 추정한다. 최종적으로 왜곡이 보정된 뷰 생성 시 역방향 사상과 함께 수평, 수직 방향에 대한 왜곡 보정 정도를 제어 가능하도록 함으로써 화각이 180도 이상인 영상에 대해서 핀홀 카메라 모델을 적용하여 2차원 평면으로 영상을 보정하는 경우 발생하는 영상 손실을 최소화하고 시각적 인지도를 높일 수 있도록 하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.228-231
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• 2006

In this paper, requirements of Meteorological Administration about Meteorological Imager (MI) of Communications, Ocean and Meteorological Satellite (COMS) is analyzed for the design of COMS ground station and according to the analysis results, the distribution image size of each observation area suitable for satellite Field Of View (FOV) stated at the requirements of meteorological administration is determined and the precise satellite FOV and the size of distribution image is calculated on the basis of the image size of the determined observation area. The results in this paper were applied to the detailed design for COMS ground station and also are expected to be used for the future observation scheduling and the scheduling of distribution of user data.

• 한국대기환경학회지
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• 제25권5호
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• pp.450-458
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• 2009

The range-dependent overlap factor of a lidar system can be determined experimentally if a Raman backscatter signal by molecule is measured in addition to the usually observed elastic backscatter signal, which consists of a molecular component and a particle component. The direct determination of the overlap profile is presented and applied to a lidar measurement according to variation of telescope field-of-view and distance between telescope and transmitting laser. The retrieval of extinction coefficient by Raman method can generate high errors for heights below planetary boundary layer if the overlap effect is ignored. The overlap correction method presented here has been successfully applied to experimental data obtained in Gwangju, Korea.

• 시스템엔지니어링학술지
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• 제15권1호
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• pp.9-15
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• 2019

DIRCM is a device that deception missiles by directing the light source to missile seeker with infra-red laser based turret. The effectiveness of the device is affected by changes of the turret's Field of View (FoV), and also influence of the interference devices determines the effect of the DIRCM's effectiveness. Therefore finding mounting location for DIRCM is critical parameter for the DIRCM's effectiveness. so we applied stiffness review, interference analysis, FoV analysis and simulation analysis method to Multi-purpose helicopter for the find DIRCM location. As a result, in case of 1 DIRCM mounted at helicopters bottom shows 30~40% survivability. case of 2 DIRCM mounted at both side shows 70~80% survivability.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.151-155
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• 2014

Although various ophthalmic imaging methods, including fundus photography and optical coherence tomography, have been applied for effective diagnosis of ocular diseases with high spatial resolution, most of them are limited by shallow imaging penetration depth and a narrow field of view. Also, many of those imaging modalities are optimized to provide microscopic anatomical information, while functional or cellular information is lacking. Compared to other ocular imaging modalities, photoacoustic imaging can achieve relatively deep penetration depth and provide more detailed functional and cellular data based on photoacoustic signal generation from endogenous contrast agents such as hemoglobin and melanin. In this paper, array-based ultrasound and photoacoustic imaging was demonstrated to visualize pigmentation in the eye as well as overall ocular structure. Fresh porcine eyes were visualized using a real-time ultrasound micro-imaging system and an imaging probe supporting laser pulse delivery. In addition, limited photoacoustic imaging field of view was improved by an imaging probe tilting method, enabling visualization of most regions of the retina covered in the ultrasound imaging.

• Current Optics and Photonics
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• 제1권4호
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• pp.336-343
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• 2017

A wide field-of-view (FOV) image contains more visual information than a conventional image. This study proposes a new type of hyperbolic mirror for wide FOV image acquisition. The proposed mirror consists of a hyperbolic cylindrical section and a bowl-shaped hyperbolic omnidirectional section. Using an imaging system with this mirror, it is possible to achieve a $213.8^{\circ}$ horizontal and a $126.94^{\circ}$ vertical maximum FOV. Parameters of each section of the mirror are designed to be continuous at the junction of the two parts, and the resultant image is seamless. The image-acquisition model is obtained using ray-tracing optics. To rectify the geometrical distortion of the original image due to the mirror, an image-restoration algorithm based on conformal projection is presented in this study. The performance of the proposed imaging system with the hyperbolic mirror and its image-restoration algorithm are verified by experiments.

• 한국지능시스템학회논문지
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• 제13권4호
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• pp.480-485
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• 2003

인쇄회로기판을 조립하는 SMT (surface mount technology) 라인의 AOI (automatic optical inspection) 형 검사기를 대상으로, 검사시간 단축을 위한 경로계획 방법을 제안한다. 기판에 존재하는 검사 윈도우들은 카메라의 FOV (field-of-view) 크기를 고려하여 클러스터링 되어야 하며, 전체 검사시간의 단축을 위하여 클러스터의 수를 최소화하는 것이 바람직하다. 주어진 기판에 대한 클러스터의 수를 최소화하기 위한 유전자 알고리즘을 새로이 제안하며, 이를 사용한 효과적 경로계획 방법을 제시한다. 상용 검사기를 대강으로 시뮬레이션을 수행하며, 비교 평가를 통하여 제안된 방법의 유용성을 검증한다.