• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.205-212
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• 2003

Many people are exposed to accidents by vehicles or sports. The most frequent injuries by these accidents is concerned with a knee joint. The three-dimensional surface model of a knee is needed for dynamic analysis of knee motion and knee reconstruction. three-dimensional motion data of a knee joint were obtained using X-ray and precise magnetic sensors. The surface data of a femur and a tibia were obtained using cross-sectional pictures by CT. The three-dimensional surface models of a femur and a tibia were made by the method of optimal triangular patch. Using obtained motion data, we simulated the motion of three-dimensional knee joint model.

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2007.10a
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• pp.623-623
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• 2007

• Journal of the Korea Society for Simulation
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• v.6 no.2
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• pp.31-44
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• 1997

In medical applications, the cooperation work using computer network is in the spotlight as next generation technology, because it offers sharing of equipments, knowledge of specialists, and data and surmounts the limitations of geographical position and time. We present a prototype of telepresent surgical simulation system in this treatise. It is a telemedicine system using volume image, which is reconstructed from radiological images such as MRI and CT. It is used as a tool for surgical simulation among telepresent doctors. It provides the functions of conference control, volume reconstruction and manipulation, and multimedia database management among one server and multi-clients through high-speed network. It is implemented on Unix workstation using X-windows and C language, TCP/IP protocol and UNiSQL as DBMS.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.6
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• pp.942-948
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• 2017

Ray-tracing based method for computing projection image calculates the exact amounts of the intersection between voxels and a ray. Among several different implementations of the ray tracing based methods, Siddon's method is the earliest one. Later faster implementation such as Jacobs's method, Zhao's method, were investigated. To our knowledge, Zhao's method is the fastest one among these. We improve the speed of the Zhao's method by predicting the number of the same intersection length between voxel and a ray. In our experiment, the proposed method showed significantly faster computation speed than Zhao's method.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.785-788
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• 2004

폐 기관지는 외부의 공기를 폐까지 전달해주는 역할을 하고 있다. 이는 병리학적, 해부학적으로 중요한 역할을 하고 있으며, 의사들에게는 기관지의 상태를 시각적으로 쉽게 판독을 할 수 있다면 폐에서 발생하는 기관지염(bronchitis), 기관지 확장증(bronchiectasis), 폐기종(pulmonary emphysema), 결핵(tuberculosis), 기흉(pneumothorax)등 여러 가지 병명을 쉽게 판독이 가능하다. 지금까지 폐 기관지에 대한 연구가 지속적으로 진행 되었으며, 2D CT 영상에서의 주변의 밀도차가 유사한 폐실 질에서의 폐기관지를 추출해 내는 것은 어려움을 Gray-scale Reconstruction과 임계치를 이용하여 추출하였다. 이는 3D 구성을 위한 전 단계로 인체 내부의 장기를 가상의 영상을 실제와 가까운 영상으로 구현하는데 쓰인다.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.96-102
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• 2020

Oral cancer surgery changes the morphologic characteristics of the human upper airway. These changes can affect the flow patterns. In this study, computational fluid dynamics (CFD) simulations with transient solver were performed to numerically investigate the air flows in the human upper airways depending oral cancer surgery. 3D reconstructed models were obtained from 2D CT images of one patient. For the boundary condition, the realistic breathing cycle of human was applied. The hydraulic diameters of cross-sections for post-surgical model are changed greatly along streamwise direction, so these variations can cause higher wall shear stress and flow disturbance compared to pre-surgical model. The recirculation flows observed in the protruding region result in the relatively large pressure drop. These results can be helpful to understand the flow variations after resection surgery of oral cancer.

• Journal of the Korean Society for Heat Treatment
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• v.37 no.2
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• pp.73-78
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• 2024

This study presents a real-time method that uses Laser Absorption Spectroscopy (LAS) to measure exhaust gas temperatures in turbulent flow fields. It was possible to measure temperature by passing a laser beam through the exhaust gas in a grid pattern, and obtain a temperature distribution image through time series analysis at 0.1 second intervals. Temperature image resolution has been improved with CT reconstruction algorithms. Estimating maximum temperature values and locations enabled 2D temperature analysis, surpassing single-point methods like thermocouples. The accuracy of LAS measurements was evaluated by comparison with thermocouple measurements. This approach will contribute to automotive technology and environmental protection by providing reliable temperature data for interpreting turbulent temperature distributions.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.25 no.3
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• pp.340-346
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• 2023

Bilateral distal anterior cerebral artery (DACA) aneurysms also called "kissing aneurysms" or "mirror aneurysm" are extremely rare, accounting for only 0.2% of all intracranial aneurysms. There have only been a few examples of mirror DACA aneurysms reported in the literature. Here, we report a rare case of mirror DACA aneurysm in a middle aged female with its successful clipping. Patient was admitted with severe headache and altered sensorium. Computed tomography (CT) head was suggestive of anterior inter-hemispheric hematoma. Digital subtraction angiography (DSA) was done which was suggestive of two distal anterior cerebral artery aneurysms located at same anatomical position. It was treated through microsurgical clipping. Mirror image DACA aneurysms are rare occurrence. All patients with ruptured DACA aneurysms should have angiography with 3D reconstruction studies. This aids in determining the aneurysm's morphology and planning treatment accordingly.

• Progress in Medical Physics
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• v.14 no.2
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• pp.131-140
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• 2003

As the importance of accuracy in measurings of 3-D anatomical structures continues to be stressed, an objective and quantitative of assessing image quality and accuracy of 3-D volume-rendered images is required. The purpose of this study was to evaluate the quantitative accuracy of 3-D rendered images obtained with MDCT, scanned at various scanning parameters (scan modes, slice thicknesses and reconstruction slice thickness). Twelve clinically significant points that play an important role for the craniofacial bone in plastic surgery and dentistry were marked on the surface of a dry human skull. The direct distances between the reference points were defined as gold standards to assess the measuring errors of 3-D images. Then, we scanned the specimen with acquisition parameters of 300 mA, In kVp, and 1.0 sec scan time in axial and helical scan modes (pitch 3:1 and 6:1) at 1,25 mm, 2.50 mm, 3.75 mm and 5.00 mm slice thicknesses. We performed 3-D visualizations and distance measurements with volumetric analysis software and statistically evaluated the quantitative accuracy of distance measurements. The accuracy of distance measurements on the 3-D images acquired with 1.25, 2.50, 3,75 and 5.00 mm slice thickness were 48%, 33%, 23%, 14%, respectively, and those of the reconstructed 1.25 mm were 53%, 41%, 43%, 36% respectively. Meanwhile, there were insignificant statistical differences (P-value<0.05) in the accuracy of the distance measurements of 3-D images reconstructed with 1.25 mm thickness. In conclusion, slice thickness, rather than scan mode, influenced the quantitative accuracy of distance measurements in 3-D rendered images with MDCT. The quantitative analysis of distance measurements may be a useful tool for evaluating the accuracy of 3-D rendered images used in diagnosis, surgical planning, and radiotherapeutic treatment.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.67-70
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• 2013

Purpose: Surge in patients with hepatocellular carcinoma, hepatic artery chemical embolization is one of the effective interventional procedures. The PET/CT examination plays an important role in determining the presence of residual cancer cells and metastasis, and prognosis after embolization. The other hand, the hepatic artery chemical embolization of embolic material used lipiodol produced artifacts in the PET/CT examination, and these artifacts results in quantitative evaluation influence. This study, the radioactivity density and the percentage error was evaluated by the extent of the impact of lipiodol in the image of PET/CT. Materials and Methods: 1994 NEMA Phantom was acquired for 2 minutes and 30 seconds per bed after the Teflon, water and lipiodol filled, and these three inserts into the enough to mix the rest behind radioactive injection with $20{\pm}10MBq$. Phantom reconfigure with the iterative reconstruction method the number of iterations for two times by law, a subset of 20 errors. We set up region of interest at each area of the Teflon, water, lipiodol, insert artifact occurs between regions, and background and it was calculated and compared by the radioactivity density(kBq/ml) and the% Difference. Results: Radioactivity density of the each region of interest area with the teflon, water, lipiodol, insert artifact occurs between regions, background activity was $0.09{\pm}0.04$, $0.40{\pm}0.17$, $1.55{\pm}0.75$, $2.5{\pm}1.09$, $2.65{\pm}1.16 kBq/ml$ (P <0.05) and it was statistically significant results. Percentage error of lipiodol in each area was 118%, compared to the water compared with the background activity 52%, compared with a teflon was 180% of the difference. Conclusion: We found that the error due to under the influence of the attenuation correction when PET/CT scans after lipiodol injection performed, and the radioactivity density is higher than compared to other implants, lower than background. Applying the nonattenuation correction images, and after hepatic artery chemical embolization who underwent PET/CT imaging so that the test should be take the consideration to the extent of the impact of lipiodol be.