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Sparse-view Image Reconstruction in Prospectively Gated Micro-CT for Fast and Low-dose Imaging
민종환,조규성,조승룡,Kyoungwoo Kim 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7
We conducted a feasibility study using a total-variation minimization algorithm for image reconstruction in prospectively gated micro computed tomography (micro-CT). The total-variation (TV) minimization algorithm exploits the sparseness of the image’s gradient magnitude and can successfully reconstruct CT images from undersampled data for which conventional analytic reconstruction algorithms fail. We implemented the algorithm and applied it to sparsely-sampled data for a mouse by using a prospectively gated micro-CT system. The images were successfully reconstructed, and an image similarity index was quantitatively calculated with respect to the reference images reconstructed from fully-sampled data. Compared to a conventional image reconstruction algorithm, the TV-minimization algorithm substantially reduced image inaccuracy related to the image artifacts.
Test Measurements and Evaluations of Industrial Three-dimensional High-penetration Tomography
한범수,강원구,이현우,김인수,강창무,민종환,이태원,조승룡 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.3
The image of the current non-destructive testing system using a high energy accelerator is limitedto conventional two-dimensional metaphysical information. Requirements for the present manufacturingindustry are growing rapidly and include quantitative measurements, high-density componentmodel extraction, reverse process development and precision inspection to meet the needs for theverification of manufactured goods. Therefore, industrial three-dimensional high-penetration tomographyhas emerged as the most promising method. In this study, in order to evaluate theapplicability of a MeV-level high-energy accelerator, we developed a three-dimensional tomographysystem using a 450 kV X-ray generator. Evaluation of the three-dimensional tomography image isbased on measurements of the penetration and the image resolution for high-energy X-rays.
나노위치제어를 이용한 연 X-선 결상현미경 시스템의 조명광학소자 정렬
김재희(Jea Hee Kim),김규겸(Kyu Gyeom Kim),민종환(Jong Hwan Min),김경우(Kyong Woo Kim),권영만(Young Man Kwon),민진영(Jin Young Min),윤권하(Kwon Ha Yoon) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
This paper presents a method of alignment for condenser mirror of soft x-ray microscopy system based on nano-positioning control. The X-ray source was focused on a sample by a doubled ellipsoidal condenser reflective mirror. X-ray source focusing will increase the photon density in the object plane and is very important to approach high resolution imaging. Required degree of freedom (DOF) of optics aligner in X-ray microscope is dependent on the kind of optics, but generally 5-DOF is needed. We used 5-axis manipulator that consists of three linear motions (X, Y and Z) and two tilting motions (Rx, Ry). A linear translation stage is adopted a kind of DC motor with a linear resolution 50nm and travel range of 5mm. The mechanism was controlled with PID controller augmented with closed feedback loop for precision control. A two axis tilt stage is employed a design resolution of 0.23μrad and tilt range of ±7deg. We have designed 5-axis manipulator for alignment of condenser mirror and developed to control algorithm by inverse kinematics. The performance of the proposed 5-DOF manipulator is evaluated by using a laser interferometer system with two plane mirror reflectors. The experimental results are depicted in this paper.
소형화 연 X-선 투과현미경을 위한 새로운 광학설계와 개발
김경우(Kyong-Woo Kim),권영만(Young-Man Kwon),김규겸(Kyu-Gyeom Kim),김재희,민종환(Jong-Hwan Min),임종혁(Jong-Hyeok Lim),남기용(Ki-Yong Nam),민진영(Jin-Young Min),윤권하(Kwon-Ha Yoon) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
In this paper the conceptual design and development of a compact vertical type soft x-ray microscope is described. This x-ray microscope operates in the water window wavelength region (2.3~4.4㎚), where natural contrast between carbon (protein) and oxygen (water) allows imaging of unstained biological material their natural, hydrated environment. Until now, operational x-ray microscopes are based on synchrotron radiation sources, which limit their accessibility. Many biologists would benefit from having the x-ray microscope as a tool among other tools in their own laboratory. For this purpose we introduced the compact vertical type soft X-ray microscope with 50 ㎚ resolution for biomedical application. The compact vertical type soft x-ray microscope is based on a laser plasma x-ray source, doubled ellipsoidal condenser reflective optics, diffractive zone plate optics and MCP coupled with CCD to record an x-ray image. The source is a liquid-jet target laser plasma source, which is practically debris free and suitable for high average power operation. The flux, brightness and bandwidth of this source has been simulated and optimized for X-ray microscopy for biology application. A doubled ellipsoidal condenser reflective mirror operates as condenser and illuminates the sample. The high resolution imaging is currently performed with a ~12% efficient Au zone plate with an outmost zone width of 36㎚. Detection is performed with a Chevron typed MCP coupled with CCD.
MEMS 센서 응용을 위한 PZT Actuator 제작에 관한 연구
이현기(HYUNKEE LEE),조성민(SUNGMIN CHO),경제홍(JEHONG KYUNG),신동철(DONGCHUL SHIN),이영규(YEONGGYU LEE),민종환(JONGHWAN MIN),강영식(YOUNGSIK KANG) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.11
MEMS 센서 응용을 위하여 Zr/Ti=52/48 조성의 sol-gel을 Multi coating하여 2㎛ 두께 의 PZT actuator를 구현하였다. 층간 pore와 표면 crack, Haze 등이 없고, 2차상이 없는 Perovskite 상을 확인하였으며, 6inch wafer에서 두께 uniformity 5% 이하의 균일한 PZT 막을 형성하였다. Pt/TiO2 하부전극을 이용하여 하부 전극의 계면 열화 현상을 극복하였으며, (111) 우선 배향성을 얻었다. 제작된 PZT actuator는 dielectric constant와 Pr 값이 각각 1200과 24(uC/㎠)의 특성을 보였고, LDV로 측정된 압전 특성은 d33값이 120pm/V로 측정되었다.