• Investigative Magnetic Resonance Imaging
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• v.5 no.1
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• pp.43-48
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• 2001

Purpose : To evaluate changes in rabbit liver parenchyma on MR images following percutaneous Holmium-166 injection, and to correlate those changes with histologic findings. Materials and methods. Holmium-166 (10-25 mCi) was percutaneously injected into the liver of rabbit (n=12) under sonographic guidance. MR images were obtained between one to two weeks (acute phasea) after the injection in four rabbits, and between two to four weeks (subacute phase) after the injection in four rabbits. Tissue specimens of these eight rabbits were obtained immediately after MR imaging. Tissue specimens were obtained without MR imaging in four rabbits (between one to two weeks in one rabbit and between three to four weeks in three rabbits). Results : Tissue specimens showed central liquefactive necrosis and peripheral coagulative necrosis containing deposition of small particles and hemorrhage. The peripheral margin of the lesions showed formation of the granulation tissue with fibrosis, which tended to be more prominent in subacute phase. The area of the necrosis tended to correlate with the dose of the radioactive Holmium-166. On MR images, the central portion of the necrosis showed hyperintensity on 72-weighted image, hypointensity on the precontrast T1-weighted images, and no enhancement on the dynamic MR images. The peripheral portion of the necrosis showed hypointensity on T2-weighted images, iso or mild hypointensity on the T1-weighted images, and mild peripheral enhancement on the delayed dynamic MR images. The peripheral margin of the lesion showed hypointensity on both T1- and T1-weighted images with increased enhancement on the delayed phase images of the dynamic MR images. Conclusion : After percutaneous Holmium-166 injection into rabbit liver parenchyma, the central portion showed liquefactive necrosis, the peripheral portion showed coagulative necrosis with granulation, fibrosis, hemorrhage and depostition of small granules. MR imaging may be helpful in evaluation of the histological change of the liver after percutaneous Holmium-166 treatment.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.11-22
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• 2004

As random access memory chip gets cheaper, it becomes affordable to realize main memory-based database systems. Consequently, reducing cache misses emerges as the most important issue in current main memory databases, in which CPU speeds have been increasing at 60% per year, compared to the memory speeds at 10% per you. In this paper, we design and implement a main-memory database system for real-time mobile GIS. Our system is composed of 5 modules： the interface manager provides the interface for PDA users； the memory data manager controls spatial and non-spatial data in main-memory using virtual memory techniques； the query manager processes spatial and non-spatial query : the index manager manages the MR-tree index for spatial data and the T-tree index for non-spatial index : the GIS server interface provides the interface with disk-based GIS. The MR-tree proposed propagates node splits upward only if one of the internal nodes on the insertion path has empty space. Thus, the internal nodes of the MR-tree are almost 100% full. Our experimental study shows that the two-dimensional MR-tree performs search up to 2.4 times faster than the ordinary R-tree. To use virtual memory techniques, the memory data manager uses page tables for spatial data, non- spatial data, T-tree and MR-tree. And, it uses indirect addressing techniques for fast reloading from disk.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.941-951
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• 1994

The resilient behavior of subbase materials, locally used in Korea. were evaluated in this study by performing laboratory MR tests. The variations of the MR value according to LVDT's location in experiments and moisture conditions, respectively, were evaluated. And, in order to determine the relevant MR characteristics of the prototype materials, laboratory model tests containing smaller particles than those of the prototype were conducted. Based on above results, the relationship of the MR and the bulk stress (${\theta}$) was suggested. The case using internal LVDT. gave much larger $M_R$ value than that using external LVDT, since the external LVDT somewhat overestimates the resilient strain. The measured $M_R$ in damp conditions ($S_r$=40%) was larger than that in wet conditions ($S_r$=70%) by about 10%. The relationship between the $M_R$ and the void ratio was linear according to particle size effect. The relationship of the $M_R$ and the bulk stress (${\theta}$) on subbase materials in damp conditions to be used in Korea could be recommended as $M_R=3960{\cdot}{\theta}^{0.60}$ psi.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.6
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• pp.1-6
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• 2009

We propose an intensity-based image registration method for medical images. The proposed registration is performed by the use of a new measure based on the entropy of conditional probabilities. To achieve the registration, we define a modified conditional entropy (MCE) computed from the joint histograms for the area intensities of two given images. And we conduct experiments with our method as well as existing methods based on the sum of squared differences (SSD), normalized correlation coefficient (NCC), normalized mutual information (NMI) criteria. We evaluate the precision of SSD-, NCC-, MI- and MCE-based measurements by comparing the registration obtained from the same modality magnetic resonance (MR) images and the different modality transformed MR/transformed CT images. The experimental results show that the proposed method is faster and more accurate than other optimization methods.

• Journal of KIISE
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• v.43 no.8
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• pp.869-877
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• 2016

In this paper, we propose an automated segmentation method of femoral cartilage in knee MR images using multi-atlas-based locally-weighted voting. The proposed method involves two steps. First, to utilize the shape information to show that the femoral cartilage is attached to a femur, the femur is segmented via volume and object-based locally-weighted voting and narrow-band region growing. Second, the object-based affine transformation of the femur is applied to the registration of femoral cartilage, and the femoral cartilage is segmented via multi-atlas shape-based locally-weighted voting. To evaluate the performance of the proposed method, we compared the segmentation results of majority voting method, intensity-based locally-weighted voting method, and the proposed method with manual segmentation results defined by expert. In our experimental results, the newly proposed method avoids a leakage into the neighboring regions having similar intensity of femoral cartilage, and shows improved segmentation accuracy.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.50-57
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• 1998

MR acoustic sound or noise due to gradient pulsings has been one of the problems in MRI, both in patient scanning as well as in many areas of psychiatric and neuroscience research, such as brain fMRI. Especially in brain fMRI, sound noise is one of the serious noise sources which obscures the small signals obtainable from the subtle changes occurring in oxygenation status in the cortex and blood capillaries. Therfore, we have studied the effects of acoustic or sound noise arising in fMR imaging of the auditory, motor and visual cortices. The results show that the acoustical noise effects on motor and visual responses are opposite. That is, for the motor activity, it shows an increased total motor activation while for the visual stimulation, corresponding(visual) cortical activity has diminished substantially when the subject is exposed to a loud acoustic sound. Although the current observations are preliminary and require more experimental confirmation, it appears that the observed acoustic-noise effects on brain functions, such as in the motor and visual cortices, are new observations and could have significant consequences in data observation and interpretation in future fMRI studies.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.231-240
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• 1998

We investigated that the fabrication and reproducing signal characteristics of tri-layered magnetoresistance (MR) element for the high density magnetic thin film heads and sensors. Magnetoresistance curve of tri-layered MR element predicted by computer modeling was saturated above external field of -15 Oe~+22 Oe, and it was shifted to linearized region as large as 4 Oe. In the case of fabricated real device, magnetoresistance curve was saturated above external field of $\pm$15 Oe, and it was shifted to linearized region as large as 4 Oe. As shown in real device, MR response curve was in good agreement with the simulation results. As a result of experimental data of reproducing output signal in real device, it retained normal sinusoidal waveforms in 1~4 Oe external magnetic field. In this magnetic field region, the fabricated heads with tri-layered MR element can be operated with good reproduced characteristics. This will be beneficial to the use of efficient processes of manufacturing elements and the vacuum deposition techniques which control thin film properties.

• Animal Bioscience
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• v.37 no.6
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• pp.1031-1040
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• 2024

Objective: This study aimed to evaluate the effect of feeding milk replacer (MR) with varying levels of lactose and the increased supply of total solids (from 750 to 960 g/d) on performance, blood metabolites, and health of Holstein male calves during the preweaning period. Methods: Forty newborn Holstein calves (10 per treatment) were blocked according to birth weight and date of birth and distributed in a randomized block design to different liquid diets: Whole milk powder (WMP) diluted to 125 g/L solids; MR with 48% lactose (48L), diluted to 125 g/L solids; MR with 53% lactose (53L), diluted to 125 g/L solids; 53L MR corrected to 160 g/L solids (16TS) by the inclusion of a solid corrector. Calves were individually housed in wood hutches, fed 6 L/d of the liquid diet, and had free water and starter concentrate access. The study lasted 56 days. Results: Liquid diet intake was higher for calves fed 16TS than for other treatments. Calves fed 16TS presented higher protein and fat intake, followed by those fed WMP and the 48L or 53L MRs. Lactose intake was higher for 16TS-fed calves, followed by 53L, 48L, and WMP-fed calves. Starter and total dry matter intake did not differ among liquid diets. The average daily gain was higher for 16TS than 48L-fed calves, with the other treatments being intermediary. The lowest feed efficiency was observed for calves fed 48L. No effects on health were observed, as well as on selected blood metabolites, except for albumin concentration, which was higher for calves fed 16TS and WMP. Conclusion: Higher total solids content (160 g/L) in MR increases nutrient intake and consequently improves the performance of dairy calves. Feeding MRs with levels of lactose up to 53% of the DM had no deleterious effect on the performance or health of the calves.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1167-1187
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• 2020

With the development of medical imaging technology, image registration has been widely used in the field of disease diagnosis. The registration between different modal images of brain magnetic resonance (MR) is particularly important for the diagnosis of brain diseases. However, previous registration methods don't take advantage of the prior knowledge of bilateral brain symmetry. Moreover, the difference in gray scale information of different modal images increases the difficulty of registration. In this paper, a multimodal medical image registration method based on image segmentation and symmetric self-similarity is proposed. This method uses modal independent self-similar information and modal consistency information to register images. More particularly, we propose two novel symmetric self-similarity constraint operators to constrain the segmented medical images and convert each modal medical image into a unified modal for multimodal image registration. The experimental results show that the proposed method can effectively reduce the error rate of brain MR multimodal medical image registration with rotation and translation transformations (average 0.43mm and 0.60mm) respectively, whose accuracy is better compared to state-of-the-art image registration methods.

• Journal of Biomedical Engineering Research
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• v.23 no.2
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• pp.101-107
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• 2002

This paper presents a segmentation algorithm to extract endocardial contour and epicardial contour of left ventricle in MR Cardiac images. The algorithm is based on a generalized gradient vector flow(GGVF) snake and a prediction of initial contour(PIC). Especially. the proposed algorithm uses physical characteristics of endocardial and epicardial contours, cross profile correlation matching(CPCM), and a mixed interpolation model. In the experiment, the proposed method is applied to short axis MR cardiac image set, which are obtained by Siemens, Medinus, and GE MRI Systems. The experimental results show that the proposed algorithm can extract acceptable epicardial and endocardial walls. We calculate quantitative parameters from the segmented results, which are displayed graphically. The segmented left vents role is visualized volumetrically by surface rendering. The proposed algorithm is implemented on Windows environment using Visual C ++.