• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.147-148
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• 2015

MRI검사 시 다양한 환자를 고려한 변화에 적절한 coil의 선택과 조건에 따른 SNR의 차이를 조사하여 우수한 SNR의 영상을 획득하고자 한다. MR영상 획득실험은 Bottle Phantom를 이용하여 Philips achieva 1.5T와 SIMENS 1.0T을 이용하여 sequence별, surface coil별로 MR영상을 획득하여 SNR를 구하였다. 주자장이 1.0T에서 가장 높은 SNR은 TSE와 FLAIR에서 knee coil, GE에서 head coil로 측정되었고, 주자장이 1.5에서 가장 높은 SNR은 TSE에서 head coil, FLAIR와 GE에서 knee coil로 측정되었다. 본 연구에서 획득한 결과를 중심으로 다양한 환자를 고려한 변화에 따른 적절한 coil의 선택과 조건에 따라 SNR의 차이를 조사하여 우수한 SNR의 영상을 제시하여야 한다.

• The Journal of the Korea Contents Association
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• v.2 no.3
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• pp.1-15
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• 2002

A noel automated brain region extraction method in single channel MR images for visualization and analysis of a human brain is presented. The method generates a volume of brain masks by automatic thresholding using a dual curve fitting technique and by 3D morphological operations. The dual curve fitting can reduce an error in clue fitting to the histogram of MR images. The 3D morphological operations, including erosion, labeling of connected-components, max-feature operation, and dilation, are applied to the cubic volume of masks reconstructed from the thresholded Drain masks. This method can automatically extract a brain region in any displayed type of sequences, including extreme slices, of SPGR, T1-, T2-, and PD-weighted MR image data sets which are not required to contain the entire brain. In the experiments, the algorithm was applied to 20 sets of MR images and showed over 0.97 of similarity index in comparison with manual drawing.

• Patent21
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• s.64
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• pp.4-10
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• 2005

본 보고서는 2005년 11월 3일 개최된 PATINEX(PATent INformation EXpo)에서 WIPO의 Mr.William Meredth가 발표한 자료인 "Trends in International Patent Statistics and Analysis"를 국문으로 재작성한 글입니다. <혁신기획팀 김민아 역>

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.4
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• pp.337-343
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• 2001

Objective. Disc displacement may affect the joint space narrowing between condyle head and glenoid fossa. This study was designed to evaluate the correlation between the joint space change and the directions of disc displacement. Study Design. Two hundreds temporomandibular joints MR images of TMD patients (170 joints) and asymptomatic volunteers (30 joints) were evaluated for this purpose. Anterior disc displacement was divided into 3 stages (normal, little to mild, and moderate to severe displacement) based on sagittal images. And sideways displacement was classified as 3 categories (center, medial and lateral displacement) based on coronal images, then joint spaces were measured at medial, central and lateral parts of condyle head on coronal MR images, respectively. The joint spaces of 7 groups divided according to the severity and the direction of disc displacement were compared. Results. The reduction of the joint space was affected by sideways disc displacement at the opposite side of the condyle head, except the cases accompanied with severe anteriorly and laterally displaced disc. Conclusion. The sideways disc displacement affected on the opposite side temporomandibular joint space width.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.314-319
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• 2008

In this paper, the electric field distribution induced inside the brain during Transcranial Magnetic Stimulation(TMS) has been thoroughly investigated in terms of tissue heterogeneity and anisotropy as well as different head models. To achieve this, first, an elaborate head model consisting of seven major parts of the head has been built based on the Magnetic Resonance(MR) image data. Then the Finite Element Method(FEM) has been used to evaluate the electric field distribution under different head models or three different conductivity conditions when the head model has been exposed to a time varying magnetic field achieved by utilizing the Figure-Of-Eight(FOE) stimulation coil. The results show that the magnitude as well as the distribution of the induced field is significantly affected by the degree of geometrical asymmetry of head models and conductivity conditions with respect to the center of the FOE coil.

• Journal of the Korea Computer Graphics Society
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• v.13 no.2
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• pp.1-15
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• 2007

In this paper, we review relevant technologies of MR (Mixed Reality) and show important components of perspective that can overcome technical limitations of the current MR. An MR technology combines real and virtual objects in a real environment, and runs interactive in real time, and is regarded as an emerging technology in a large part of the future of IT (Information Technology). We've grouped the major obstacles limiting the wider use of MR technologies into three themes: technological limitations (i,e., tracking, rendering, authoring, and registration), user interface limitations(i.e. UI metaphor for MR interaction), and social acceptance Issues.

• Imaging Science in Dentistry
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• v.33 no.2
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• pp.107-112
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• 2003

Purpose : To determine the relationship between clinical symptoms and magnetic resoncance (MR) images in patients presenting with temoporomandibular joint (TMJ) disorders. Materials and Methods: This study was based on 172 joints in 86 patients presenting with TMJ disorders. Joint pain and sound during jaw opening and closing movements were recorded, and the possible relationship between disc positions and bony changes of the condylar head and the articular fossa in MR images in the oblique sagittal planes were examined. Data were analyzed by Chi-square test. Results : There was no statistically significant relationship between clinical symptoms and MR images in the patients with TMJ disorders. Conclusion: In the patient with TMJ disorders, joint pain and sound could not be specific clinical symptoms that are related with MR image findings, and asymptomatic joints did not necessarily imply that the joints are normal according to MR image findings.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.542-551
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• 2000

In this paper, a novel technique is presented for automatic brain region segmentation in single channel MR image data sets for 3D visualization and analysis. The method detects brain contours in 2D and 3D processing of four steps. The first and the second make a head mask and an initial brain mask by automatic thresholding using a curve fitting technique. The stage 3 reconstructs 3D volume of the initial brain mask by cubic interpolation and generates an intermediate brain mask using morphological operation and labeling of connected components. In the final step, the brain mask is refined by automatic thresholding using curve fitting. This algorithm is useful for fully automatic brain region segmentation of T1-weighted, T2-weighted, PD-weighted, SPGR MRI data sets without considering slice direction and covering a whole volume of a brain. In the experiments, the algorithm was applied to 20 sets of MR images and showed over 0.97 in comparison with manual drawing in similarity index.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.710-715
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• 1995

Magnetic domains were observed using an image lock-in technique for backscattered electron contrast (Type II) with a 200 kV scanning electron microscope. Backscattered electrons indicate a difference in magnetic domain structures at the upper and lower parts of the upper pole in thin-film heads, changing the acceleration voltage. With this method, it is also possible to observe the domain structure of the thin-film head pole through a 10 to $20\;\mu\textrm{m}$ protective layer, and the upper shield of the MR head through the coil in the resist, alumina overcoat, and upper pole.

• Progress in Medical Physics
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• v.7 no.1
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• pp.3-7
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• 1996

The accuracy in target localization of CT, MR, and digital angiography were investigated for stereotactic radiosurgery. The images using CT and MR were obtained out of geometrical phantom which was designed to produce exact coordinates of several points within a 0.lmm error range. The slice interval was 3mm and FOV was 35cm for CT and 28cm for MR. These images were transferred to treatment planning computer using TCP/IP in forms of GE format. Measured 3-D coordinates of these images from planning computer were compared to known values by geometrical phantom. Anterior-posterior and lateral films were taken by digital angiography for measurement of spatial accuracy. Target localization errors were 1.2${\pm}$0.5mm with CT images, 1.7${\pm}$0.4mm with MR-coronal images, and 2.1${\pm}$0.7mm with MR-sagittal images. But, in case of MR-axial images, the target localization error was 4.7${\pm}$0.9mm. Finally, the target localization error of digital angiography was 0.9${\pm}$0.4mm. The accuracy of diagnostic machines such as CT, MR, and angiography depended on their resolutions and distortions. The target localization error mainly depended on the resolution due to slice interval with CT and the image distortion as well as the resolution with MR However, in case of digital angiography, the target localization error was closely related to the distortion of fiducial markers. The results of our study should be considered when PTV (Planning Target Volume) was determined.