• Journal of radiological science and technology
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• v.34 no.3
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• pp.215-219
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• 2011

Monte Carlo simulation was performed to investigate optimal system of proton computed tomography and to avoid the errors by using data from X ray computed tomography in proton therapy. The informations from two DSSDs to measure position and LYSO scintillation detector to measure the residual energy of proton particle in GEANT4 were used for reconstruction computed tomography.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.351-359
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• 2009

We have developed a computer simulator fur cone-beam computed tomography (CBCT) based on the commercial Monte Carlo code, MCNP. All the functions to generate input files, run MCNP, convert output files to image data, reconstruct tomographs were realized in graphical user-interface form. The performance of the simulator was demonstrated by comparing with the experimental data. Although some discrepancies were observed due to the ignorance of the detailed physics in the simulation, such as scattered X-rays and noise in image sensors, the overall tendency was well agreed between the measured and simulated data. The developed simulator will be very useful for understanding the operation and the better design of CT systems.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.1
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• pp.36-42
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• 2009

We have developed software for converting the volumetric voxel data obtained from X-ray computed tomography(CT) into computer-aided design(CAD) data. The developed software can used for non-destructive testing and evaluation, reverse engineering, and rapid prototyping, etc. The main algorithms employed in the software are image reconstruction, volume rendering, segmentation, and mesh data generation. The feasibility of the developed software is demonstrated with the CT data of human maxilla and mandible bones.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.1
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• pp.20-30
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• 2010

In this paper, a new tomographic scan method with fixed installed detectors and rotating source from gamma projector was presented to diagnose the industrial plants which were impossible to be examined by conventional tomographic systems. Weight matrix calculation method which was suitable for volumetric detector and statistical iterative reconstruction method were applied for reconstructing the simulation and experimental data. Monte Carlo simulations had been performed for two kinds of phantoms. Lab scale experiment with a same condition as one of phantoms, had been carried out. Simulation results showed that reconstruction from photopeak counting measurement gave the better results than from the gross counting measurement although photopeak counting measurement had large statistical errors. Experimental data showed the similar result as Monte Carlo simulation. Those results appeared to be promising for industrial tomographic applications, especially for petrochemical industries.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.576-579
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• 2008

Electrical impedance(EIT) for the multi-phase flow visualization is an imaging modality in which the resistivity distribution of the unknown object is estimated based on the known sets of injected currents and measured voltages on the surface of the object. In this paper, an EIT reconstruction algorithm based on the extended Kalman filter(EKF) is proposed. The EIT reconstruction problem is formulated as a dynamic model which is composed of the state equation and the observation equation, and the unknown resistivity distribution is estimated recursively with the aid of the EKF. To verify the reconstruction performance of the proposed algorithm, experiments with simulated multi-phase flow are performed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.9
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• pp.642-648
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• 2019

In this study, Image-based computational analysis using the developed models was performed to predict the degradation of effective properties by ablation. The ablation tests of carbon/phenolic composites were performed using a 0.4 MW arc-heated wind tunnel. The carbon/phenolic composite samples were scanned using the micro-computed tomography (Micro-CT) to analyze the ablation characteristics according to a duration time of the ablation test. By calibrating the scanned images, computational models were developed that reflect the actual microstructure of the ablation composites. Also, nine computational models that reflect the actual pore shape were developed using the created cross-sectional images. Image-based computational analysis using the developed models was performed to predict the degradation of effective properties by ablation and the decrease of effective properties was confirmed with increase of porosity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.195-196
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• 2006

Direct laser sintering (DLS) technology for the resign coated sand is one of attractive technologies to produce molds and cores for the foundry industry rapidly and cost effectively. The objective of this case study is to develop casting pilot models using computer simulation technology, DLS RP machine and industrial computed tomography. The proposed casting design was verified by the Z-Cast software in the fields of fluid flow and solidification during the casting process. Casting parts with aluminum alloy using the post-curing treated sand moulds and cores are accurate to dimension and defect free.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.699-702
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• 2004

단층촬영에 의해 획득된 흉부영상의 폐 영역은 기관지, 폐동맥, 폐정맥으로 구성된 복잡한 형태를 가지고 있다. 또한 이들 조직과 폐 영역 내에 존재하는 악성 종양과 같은 질병들 사이의 공간정보의 유사성으로 인해 방사선 전문의조차도 질병을 간단히 구분 해내는데 많은 어려움이 따른다. 따라서 본 논문에서는 이러한 유사한 공간정보를 갖는 폐 영역을 수리형태학 필터인 모폴로지(morphology)와 국부적인 워터쉐드(watershed) 알고리즘을 이용하여 분할하고, 분할된 폐 영역으로부터 색전 또는 종양 등의 결절(nodule)의 정보를 가지고 있는 혈관들을 추출하는 효과적인 알고리즘을 제안한다.

• Journal of the Korean Society of Radiology
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• v.82 no.6
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• pp.1534-1544
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• 2021

Purpose To examine the effect of lung volume on the size and volume of pulmonary subsolid nodules (SSNs) measured on CT. Materials and Methods A total of 42 SSNs from 31 patients were included. CT examination was first performed at total lung capacity (TLC), and a section containing the nodule was additionally scanned at tidal volume (TV). The diameter and volume of each SSN, as well as the cross-sectional lung area containing the nodule, were measured. The significance of the changes in measurements between TLC and TV within the same individuals was evaluated. Results The lung area and the diameter and volume of SSNs decreased significantly at TV by 12.7 cm², 0.5 mm, and 46.4 mm³ on average, respectively (p < 0.001), compared to those at TLC. Changes in lung area between TV and TLC were positively correlated with the change in SSN diameter (p = 0.027) and volume (p = 0.014). However, after correction (by considering the change in lung area), the changes in SSN diameter (p = 0.124) and volume (p = 0.062) were not significantly different. Conclusion SSN size and volume can be significantly affected by lung volume during CT scans of the same individuals.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.4
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• pp.249-256
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• 2019

This paper presents an optimization framework of electrical impedance tomography for characterizing electrical conductivity profiles of concrete structures in two dimensions. The framework utilizes a partial-differential-equation(PDE)-constrained optimization approach that can obtain the spatial distribution of electrical conductivity using measured electrical potentials from several electrodes located on the boundary of the concrete domain. The forward problem is formulated based on a complete electrode model(CEM) for the electrical potential of a medium due to current input. The CEM consists of a Laplace equation for electrical potential and boundary conditions to represent the current inputs to the electrodes on the surface. To validate the forward solution, electrical potential calculated by the finite element method is compared with that obtained using TCAD software. The PDE-constrained optimization approach seeks the optimal values of electrical conductivity on the domain of investigation while minimizing the Lagrangian function. The Lagrangian consists of least-squares objective functional and regularization terms augmented by the weak imposition of the governing equation and boundary conditions via Lagrange multipliers. Enforcing the stationarity of the Lagrangian leads to the Karush-Kuhn-Tucker condition to obtain an optimal solution for electrical conductivity within the target medium. Numerical inversion results are reported showing the reconstruction of the electrical conductivity profile of a concrete specimen in two dimensions.