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Kim, Guna,Park, Soyoung,Je, Uikyu,Cho, Hyosung,Park, Chulkyu,Kim, Kyuseok,Lim, Hyunwoo,Lee, Dongyeon,Lee, Hunwoo,Park, Yeonok,Woo, Taeho Springer-Verlag 2018 Journal of medical and biological engineering Vol.38 No.1
<P>In recent computed tomography (CT) reconstruction, iterative methods have been often used owing to the potential to provide three-dimensional (3D) images of superior reconstruction quality to common filtered-back-projection (FBP)-based methods. However, these methods require enormous computational cost in the iterative process, which has still been an obstacle to put them to practical use. In this work, to overcome these difficulties, we propose a new cone-beam CT reconstruction with a dual-resolution voxelization strategy for a small region-of-interest (ROI) reconstruction in which the voxels outside the target ROI are binned by, for example, 2 x 2 x 2, 4 x 4 x 4, 8 x 8 x 8, etc., while the other voxels remain unbinned. We considered a compressed-sensing (CS)based algorithm with a dual regularization strategy, rather than common FBP-based methods, for more accurate CT reconstruction. We implemented the proposed CS-based algorithm and performed a systematic simulation and experiment. Our results indicate that the proposed method seems to be effective for reducing computational cost considerably in iterative CT reconstruction, keeping the reconstruction quality inside the target ROI not much degraded.</P>
Fault Diagnosis of Ball Bearings within Rotational Machines Using the Infrared Thermography Method
Dongyeon Kim,Hanbit Yun,Sungmo Yang,Wontae Kim,Dongpyo Hong 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.6
In this paper, the novel approach for the fault diagnosis of the bearing equipped with rotational mechanical facilities was studied. As research works, by applying the ball bearing used extensively in many industrial fields, experiments were conducted in order to propose the new prognostic method about the condition monitoring for the rotational bodies based on the condition analysis of infrared thermography. Also, by using the vibration spectrum analysis, the real time monitoring was performed. As results, it was confirmed that infrared thermography method could be adapted into monitor and diagnose the fault for bearing by evaluating quantitatively and qualitatively the temperature characteristics according to the condition of the ball bearing.
Kim, Kyuseok,Park, Soyoung,Kim, Guna,Cho, Hyosung,Je, Uikyu,Park, Chulkyu,Lim, Hyunwoo,Lee, Dongyeon,Lee, Hunwoo,Park, Yeonok,Woo, Taeho SPRINGER VERLAG KG 2018 RESEARCH IN NONDESTRUCTIVE EVALUATION Vol.29 No.2
<P>Digital tomosynthesis (DTS) has been widely used in both industrial nondestructive testing and medical x-ray imaging as a popular multiplanar imaging modality. However, although it provides some of the tomographic benefits of computed tomography (CT) at reduced dose and imaging time, the image characteristics are relatively poor due to blur artifacts originated from incomplete data sampling for a limited angular range and also aspects inherent to imaging system, including finite focal spot size of the x-ray source, detector resolution, etc. In this work, in order to overcome these difficulties, we propose an intuitive method in which a compressed-sensing (CS)-based deblurring scheme is applied to the projection images before common DTS reconstruction. We implemented the proposed deblurring algorithm and performed a systematic experiment to demonstrate its viability for improving the image characteristics in DTS. According to our results, the proposed method appears to be effective for the blurring problems in DTS and seems to be promising to our ongoing application to x-ray nondestructive testing.</P>