• Progress in Medical Physics
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• v.17 no.4
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• pp.246-251
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• 2006

The purpose of this study was to evaluate SUV (standard uptake value) using different reconstruction methods in whole body PET/CT Imaging. PET/CT studies were peformed with and without correction for effect of contrast media. The patients data were acquired using GE DSTe commercial PET/CT system. The liver disease (hepatocellular carcinoma, HCC) and renal disease (renal ceil carcinoma, RCC) patients were selected for this study, The PET/CT data were reconstructed using post CT scan with and without correction for effect of contrast media. We selected ROIs (region of Interest) at the same location and same area for the same patient to compare SUVs in these two methods. For HCC and RCC, the average differences of SUVs were measured as $1.5{\pm}1.2%\;and\;1.0{\pm}0.9%$, respectively. For HCC and RCC, the maximum differences of SUVs were measured as 4.3% and 1.9%, respectively. We observed that SUVs without correction for effect of contrast media were higher than SUVs with correction for effect of contrast media. However the differences of SUVs were very minimal. These results may be limited to HCC and RCC and further studies will be Heeded for other organs or diseases to see any changes in SUV with and without correction for effect of contrast media.

• Journal of Korea Multimedia Society
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• v.15 no.9
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• pp.1075-1085
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• 2012

In clinical research using medical images, the image segmentation is one of the most important processes. Especially, the hippocampal atrophy is helpful for the clinical Alzheimer diagnosis as a specific marker of the progress of Alzheimer. In order to measure hippocampus volume exactly, segmentation of the hippocampus is essential. However, the hippocampus has some features like relatively low contrast, low signal-to-noise ratio, discreted boundary in MRI images, and these features make it difficult to segment hippocampus. To solve this problem, firstly, We selected region of interest from an experiment image, subtracted a original image from the negative image of the original image, enhanced contrast, and applied anisotropic diffusion filtering and gaussian filtering as preprocessing. Finally, We performed an image segmentation using two level set methods. Through a variety of approaches for the validation of proposed hippocampus segmentation method, We confirmed that our proposed method improved the rate and accuracy of the segmentation. Consequently, the proposed method is suitable for segmentation of the area which has similar features with the hippocampus. We believe that our method has great potential if successfully combined with other research findings.

• Journal of the Korean Magnetic Resonance Society
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• v.5 no.2
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• pp.99-109
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• 2001

Authors investigated neuronal changes of local cellular metabolism in the cerebral lesions of Parkinsonian symptomatic side between before and after stereotactic neurosurgery by follow-up 1H magnetic resonance spectroscopy (MRS). Patients with Parkinson's disease (PD) (n = 15) and age-matched normal controls (n = 15) underwen MRS examinations using a stimulated echo acquisition mode (STEAM) pulse sequence that provided 2${\times}$2${\times}$2 ㎤ (8ml) volume of interest in the regions of substantia nigra, thalamus, and lentiform nucleus. Spectral parameters were 20 ms TE, 2000 ms TR, 128 averages,2500 Hz spectral width, and 2048 data points. Raw data were processed by the SAGE data analysis package (GE Medical Systems). Peak areas of N-acetylaspartate (NAA), creatine (Cr), choline-containing compounds (Cho), inositols (Ins), and the sum (Glx) of glutamate and GABA were calculated by means of fitting the spectrum to a summation of Lorentzian curves using Marquardt algorithm. After blindly processed, we evaluated neuronal alterations of observable metabolite ratios between before and after stereotactic neurosurgery using Pearson product-moment analysis (SPSS, Ver. 6.0). A significant reduction of NAA/Cho ratio was observed in the cerebral lesion in substantia nigra of PD patient related to the symptomatic side after neurosurgery (P : 0.03). In thalamus, NAA/Cho ratio was also significantly decreased in the cerebral lesion including the electrode-surgical region (P : 0.03). A significant reduction of NAA/Cho ratio in lentiform nucleus was not oberved, but tended toward significant reduction after neurosurgery (P = 0.08). In particular, remarkable lactate signal was noted from the surgical thalamic lesions of 6 among 8 patients and internal segments of globus pallidus of 6 among 7 patients, respectively. Significant metabolic alterations of NAA/Cho ratio might reflect functional changes of neuropathological processes in the lesion of substantia nigra, thalamus, and lentiform nucleus, and could be a valuable finding fur evaluation of Parkinson's disease after neurosurgery. Increase of lactate signals, being remarkable in surgical lesions, could be consistent with a common consequence of neurosurgical necrosis. Thus, IH MRS could be a useful modality to evaluate the diagnostic and prognostic implications fur Parkinsons disease after functional neurosurgery.

• Progress in Medical Physics
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• v.10 no.1
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• pp.23-32
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• 1999

Combined MRI and Relaxogram approach was introduced as a very useful tool for fat study. The phantoms simulating homogeneous mixture of fat and non-fat environments were measured with spin echo pulse sequence on a 0.15 T whole body imager. From 45 scans, the Tl values were obtained by fitting the data to continuous distribution (CONTIN) of relaxation time. This relaxogram gives broad distributions of relaxation time, which are characterized by a number of peaks with characteristic T1 values. Two distinct peaks in relaxogram were observed and identified as signals from com oil and gelatin gel. This model system can be served as simulating the distribution of fat in muscle. Also the relative ratio of two components, which is proportional to the area under the peak, is estimated and compared to nominal values. Based on the good agreement between two predictions, the values from our proposed method agreed with nominal values within $\pm$7 % error. The effects of different concentration of contrast agent and different region of interest are presented. To optimize total scan times, the minimum required data points and so further reduction in total scan times are discussed.

• The KIPS Transactions:PartB
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• v.19B no.2
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• pp.99-106
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• 2012

The purpose of this study was to determine the evaluation parameters' osteoporosis predictability in accordance with measuring regions by analyzing the correlations between bone mineral density and trabecular patterns derived from different measuring regions. Experimental subjects were a total of 40 female patients after menopause aged over 40 years, and were classified into 20 control and 20 osteoporotic groups according to the T-score. Bone mineral density was measured on femoral neck, trochanter and ward's triangle by DEXA(Dual Energy X-ray Absorptiometry). We designated ROI(Region of Interest) with $50{\times}50$ pixel size on each measuring regions, and extracted trabecular patterns by using existing image processing method. We also selected a total of eight evaluation parameters that are categorized into structural(mean gray level, area, perimeter, thickness and terminal distance), skeletonized parameters(number, length) and fractal dimension. As a result, it was observed that area, perimeter, thickness, terminal distance, number, length and fractal dimension reflected the bone mineral density with high statistical validity(p<0.003). We also confirmed that the evaluation parameters could predict the osteoporosis more efficiently.

• The Korean Journal of Financial Management
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• v.22 no.2
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• pp.71-89
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• 2005

The purpose of this research is to examine X-efficiency of Korean local credit unions in 2001 by employing the stochastic frontier approach. This study uses the intermediation approach in order to define outputs and inputs of the credit unions. We define the outputs as the amounts of loans, and securities. The inputs are labor, deposit and physical capital. The price of labor is estimated by dividing the total wages by the number of employees. The price of deposit equals total interest divided by total deposit, and the price of physical capital is also computed to divide the total sales and administrative expenses by the physical capital. By the result of this study, the average efficiency score is 0.81. This fact indicates that credit unions can reduce their inputs by 19% for the given outputs. If results are arranged into quartiles based on the efficiency, inefficiency of top 25% credit unions is below 9%, and half of them is over 17%. In addition, e result shows that the efficiency is significantly influenced by region and size even if credit unions in Seoul and Daegu showed little difference in efficiency by size. Generally, medium size credit unions are more efficient than large size.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.97-106
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• 1989

This paper is on the modeling of two-dimensional groundwater flow, which is the first step of the development of Dynamic System Model for groundwater flow and pollutant transport in subsurface porous media. The particular features of the model are its versatility and flexibility to deal with as many real-world problems as possible. Points as well as distributed sources/sinks are included to represent recharges/pumping and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Sources/sinks strength over each element and node, hydraulic head at each Dirichlet boundary node and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution methed for the matrix equation approximating the partial differential equation of groundwater flow. The model also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. The groundwater flow model shall be combined with the model of pollutant transport in subsurface porous media. Then the combined model, with the applications of the Eigenvalue technique and the Dynamic system theory, shall be improved to the Dynamic System Model which can simulate the real groundwater flow and the pollutant transport accurately and effectively for the analyses and predictions.

• Archives of design research
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• v.19 no.4 s.66
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• pp.111-120
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• 2006

These days, contemporary people's interest in culture is higher than ever, and in response to such a current trend, each country is making efforts to search for its identity in various areas, and conducting research to compare its culture with that of other countries. The culture of a region does not develop independently or spontaneously, but it changes and evolves in connection with neighboring countries or cultures. Thus, in order to understand our own cultural characteristics properly, we need not only to make an in-depth study in our own culture but also to compare it with other cultures and understand their similarities and differences dearly. From old times, Korea, China and Japan have had great influences on one another through active socio cultural exchange and at the same time they have their own unique cultural characteristics. Unfortunately, however, the distinguished identity of Korean culture has not been recognized properly. The present study purposed to classify Korean, Chinese and Japanese traditional furniture from the $14th{\sim}19th$ century by type, and compare their characteristics by type as well as their general formative characteristics. This research is expected to improve our objective understanding of our own culture. Furthermore, it will provide a ground for reinterpreting our culture to distinguish Korean culture from Oriental culture.

• Korean Security Journal
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• no.60
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• pp.155-173
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• 2019

This study touches upon the challenges of globalization, in which terrorism is one of the most brutal forms of criminal violence targeting innocent people. No country is immune from terrorist attacks, and no person is immune from becoming a victim. Interest in this topic is increasing as terrorism, in all its forms and manifestations, in its scale and intensity, and in its inhumanity and cruelty, is now becoming one of the most acute and pressing problems of global importance. Legal regulations passed in Mongolia in 2004 have established a structure to prevent and detect terrorist threats. However, the country's anti-terrorism policy should be improved with respect to its global counter-terrorism strategy. Because Mongolia is a comparatively safe country in the region, the people do not consider terrorism to be a real threat. This study aims to suggest methods to quickly raise awareness and create a security culture to improve Mongolia's long-term terrorism prevention policy. In particular, the authors review Mongolia's anti-terrorism policy, focusing on legal regulations, and suggest education methods to raise terrorism awareness for the public as a primary preventive measure. The study also presents a comparative analysis and a summary conclusion by examining international legal acts, conventions on new manifestations of terrorism, the foundations of laws and regulations of Mongolia, and related research on terrorism.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.120-120
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• 1998

Boron nitride (BN) films have attracted a growing interest for a variety of t technological applications due to their excellent characteristics, namely hardness, c chemical inertness, and dielectrical behavior, etc. There are two crystalline phases 1551; of BN that are analogous to phases of carbon. Hexagonal boron nitride (h-BN) has a a layered s$\sigma$ucture which is spz-bonded structure similar to that of graphite, and is t the stable ordered phase at ambient conditions. Cubic boron nitride (c-BN) has a z zinc blende structure with sp3-bonding like as diamond, 따ld is the metastable phase a at ambient conditions. Among of their prototypes, especially 삼Ie c-BN is an i interesting material because it has almost the same hardness and thermal c conductivity as di없nond. C Conventionally, significant progress has been made in the experimental t techniques for synthesizing BN films using various of the physical vapor deposition 밍ld chemical vapor deposition. But, the major disadvantage of c-BN films is that t they are much more difficult to synthesize than h-BN films due to its narrow s stability phase region, high compression stress, and problem of nitrogen source c control. Recent studies of the metalorganic chemical vapor deposition (MOCVD) of I III - V compound have established that a molecular level understanding of the d deposition process is mandatory in controlling the selectivity parameters. This led t to the concept of using a single source organometallic precursor, having the c constituent elements in stoichiometric ratio, for MOCVD growth of 삼Ie required b binary compound. I In this study, therefore, we have been carried out the growth of h-BN thin f films on silicon substrates using a single source precursors. Polycrystalline h-BN t thin films were deposited on silicon in the temperature range of $\alpha$)() - 900 $^{\circ}$C from t the organometallic precursors of Boron-Triethylamine complex, (CZHs)3N:BRJ, and T Tris(dimethylamino)Borane, [CH3}zNhB, by supersonic molecular jet and remote p plasma assisted MOCVD. Hydrogen was used as carrier gas, and additional nitrogen w was supplied by either aDlIDonia through a nozzle, or nitrogen via a remote plasma. T The as-grown films were characterized by Fourier transform infrared spectroscopy, x x-ray pthotoelectron spectroscopy, Auger electron spectroscopy, x-ray diffraction, t transmission electron diffraction, optical transmission, and atomic force microscopy.roscopy.