• Progress in Medical Physics
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• v.19 no.4
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• pp.256-262
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• 2008

To evaluate the metabolic changes in normal adult brains due to alterations SENSE and NEX (number of excitation) by multi voxel MR Spectroscopy at 3.0 Tesla. The study group was composed of normal volunteers (5 men and 8 women) with a mean ($\pm$ standard deviation) age of 41 (${\pm}11.65$). Their ages ranged from 28 to 61 years. MR Spectroscopy was performed with a 3.0T Achieva Release Version 2.0 (Philips Medical System-Netherlands). The 8 channel head coil was employed for MRS acquisition. The 13 volunteers underwent multi voxel spectroscopy (MVS) and single voxel spectroscopy (SVS) on the thalamus area with normally gray matter. Spectral parameters were as follows: 15 mm of thickness; 230 mm of FOV (field of view); 2000 msecs of repetition time (TR); 288 msecs of echo time (TE); $110{\times}110$ mm of VOI (view of interest); $15{\times}15{\times}15$ mm of voxel size. Multi voxel spectral parameters were made using specially in alteration of SENSE factor (1~3) and 1~2 of NEX. All MRS data were processed by the jMRUI 3.0 Version. There was no significant difference in NAA/Cr and Cho/Cr ratio between MVS and SVS likewise the previous results by Ross and coworkers in 1994. In addition, despite the alterations of SENSE factor and NEX in MVS, the metabolite ratios were not changed (F-value : 1.37, D.F : 3, P-value : 0.262). However, line-width of NAA peak in MVS was 3 times bigger than that in SVS. In the present study, we demonstrated that the alterations of SENSE factor and NEX were not critically affective to the result of metabolic ratios in the normal brain tissue.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.114-118
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• 1997

Purpose: Functional MR imaging is the method of demonstrating changes in regional cerebral blood flow produced by sensory, motor, and any other tasks. Functional MR of visual cortex is performed as a patient stares a photic stimulation, so adaptable photic stimulation is necessary. The purpose of this study is to evaluate whether the size of photic stimulator can affect the degree of visual cortex activation. Materials and Methods: Functional MR imaging was performed in 5 volunteers with normal visual acuity. Photic stimulator was made by 39 light-emitting diodes on a plate, operating at 8Hz. The sizes of photic stimulator were full field, half field and focal central field. The MR imager was Siemens 1.5-T Magnetom Vision system, using standard head coil. Functional MRI utilized EPI sequence (TR/TE= 1.0/51. Omsec, matrix $No.=98{\times}128$, slice thickness=8mm) with 3sets of 6 imaging during stimulation and 6 imaging during rest, all 36 scannings were obtained. Activation images were obtained using postprocessing software(statistical analysis by Z-score), and these images were combined with T-1 weighted anatomical images. The activated signals were quantified by numbering the activated pixels, and activation a index was obtained by dividing the pixel number of each stimulator size with the sum of the pixel number of 3 study using 3 kinds of stimulators. The correlation between the activation index and the stimulator size was analysed. Results: Mean increase of signal intensities on the activation area using full field photic stimulator was about 9.6%. The activation index was greatest on full field, second on half field and smallest on focal central field in 4. The index of half field was greater than that of full field in 1. The ranges of activation index were full field 43-73%(mean 55%), half field 22-40 %(mean 32%), and focal central field 5-24%(mean 13%). Conclusion: The degree of visual cortex activation increases with the size of photic stimulator.

• Journal of Chest Surgery
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• v.29 no.4
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• pp.373-380
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• 1996

Prevention of thromboembolism is the most important task in the development of bioconpatible small caliber artificial vascular graft. In normal vessels, vascular endothelial cells maintain homeosatsis by secreting numerous factors. The aim of this study is to develope a method which Improves biocompatibility of small caliver polyurethane graft using endothelial cell culture technique, and ev luate the efTectiveness of extracelluar matrix for endothelization which was produced by cultured fibroblast. Methods ; Multiporous polyurethane tube of 3 mm diameter, 0.3 mm thickness was manufactured for vascular graft. Three mongrel dogs were intubated and internal jugular veins removed. Extracelluar matrix produced by cultured flbrobast which was obtained from dog's internal jugular vein were coated to the polyurethane graft. Then, endothelial cells extracted from Jugular vein were cultured and fixed on the extracelluar matrix layer of vascular graft. Endothelial cell coated vascular grafts were implanted to the carotid arteries of experimental dogs as interposed autograft. Implanted grafts were removed after 3 and 6 weeks. As a control, PTFE graft was interposed on carotid artery. These experiments demonstrated that extracelluar matrix produced by fibroblast can afford a base for endothelial cell linings of polyurethane graft. Although thrombosis were developed on autografted en othelial cell coated graft, 33% opening was noticed, and showed less adhesion to adjacent tissue layer. These findings suggest that fiboblast produced extracelluar matrix which can be used for edothelial cell lining vascular graft, and by improving the cultured endothelial cell function, there will be a new modality for reducing thrombosis on small vascular graft.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.348-353
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• 1997

Hydrogenated amorphous carbon(a-C:H) films were deposited on p-type Si(100) by DC saddle-field plasma enhanced CVD to investigate the effect of substrate bias on optical properties and structural changes. They were deposited using pure methane gas at a wide range of substrate bias at room temperature and 90 mtorr. The substrate bias voltage ($V_s$) was employed from $V_s=0 V$ to $V_s=400 V$. The information of optical properties was investigated by photoluminescence and transmitance. Chemical bondings of a-C:H have been explored from FT-IR and Raman spectroscopy. The thickness and relative hydrogen content of the films were measured by Rutherford backscattering spectroscopy (RBS) and elastic recoil detection (ERD) technigue. The growth rate of a-C:H film was decreased with the increase of $V_s$, but the hydrogen content of the film was increased with the increase of $V_s$. The a-C:H films deposited at the lowest $V_s$ contain the smallest amount of hydrogen with most of C-H bonds in the of $CH_2$ configuration, whereas the films produced at higher $V_s$ reveal dominant the $CH_3$ bonding structure. The emission of white photoluminescence from the films were observed even with naked eyes at room temperature and the PL intensity of the film has the maximum value at $V_s$=200 V. With $V_s$ lower than 200 V, the PL intensity of the film increased with V, but for V, higher than 200 V, the PL intensity decreased with the increase of $V_s$. The peak energy of the PL spectra slightly shifted to the higher energy with the increase of $V_s$. The optical bandgap of the film, determined by optical transmittance, was increased from 1.5 eV at $V_s$=0V to 2.3 eV at $V_s$=400 V. But there were no obvious relations between the PL peak and the optical gap which were measured by Tauc process.

• Clinical and Experimental Pediatrics
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• v.52 no.2
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• pp.220-226
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• 2009

Purpose : Macrovascular complications are the main cause of mortality in type 1 diabetes mellitus (T1DM). The purpose of this study was to clarify the presence of early vascular changes and to assess the risk factors of macrovascular complications in young adults with T1DM diagnosed in childhood and adolescence. Methods : Seventy-two patients ($23.9{\pm}2.4$ years) with T1DM diagnosed before 18 years of age and twenty normal controls were included. The incidence of hypertension, dyslipidemia, and other risk factors of macrovascular complication were reviewed. Flow-mediated vasodilation (FMD) and mean intima-media thickness (IMT) measured by ultrasound were compared between patients and control subjects, and their correlations with macrovascular risk factors were analyzed. Results : Of the 72 patients, 32 (44.4%) had hypertension. The proportions of maleness (P=0.03) and mean body mass index (P=0.04) were higher in the hypertensive patients than in normotensive patients. Thirty-one (N=69, 44.9%) patients had dyslipidemia and LDL-cholesterol was positively correlated with mean HbA1c (r=0.32, P=0.008) and total daily insulin dose (r=0.27, P=0.02). The mean IMT was significantly higher in patients than in control subjects ($0.43{\pm}0.06$ mm vs $0.39{\pm}0.06$ mm, P=0.03). There was no difference in the value of FMD between patients and controls, but the duration of the disease after pubertal onset was negatively correlated with FMD (r=-0.34, P=0.01). Conclusion : Hypertension, dyslipidemia and atherosclerotic vascular change were observed in young adults with T1DM diagnosed during childhood and adolescence; this strongly suggests that meticulous screening of macrovascular complications and control of their risk factors should be conducted.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.4
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• pp.62-71
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• 2014

Three types of diffuser systems were manufactured and applied to investigate the effect of liquid fertilization of pig manure slurry by application of aeration processes. In the first type reactor, commonly used diffuser system, which diffuse air upward by diffusing aerator fixed at the bottom of the reactor is installed. In case of the second type, air diffuser is installed 10 cm above of the bottom of a reactor. In the third type reactor, the venturi-type air diffuser is installed at circulation pipe, which return pig slurry in the reactor(mixing-in-pipe process). The pig manure slurry separated to solid/liquid was flowed into the experimental reactor, and left as it for one week to precipitate solids. The concentration of organic matter, T-N, T-P and BOD in the raw pig manure slurry flowed into the reactor of bottom-fixed type aeration process were 1.82%, 4,400 mg/L, 360 mg/L and 13,542 mg/L, respectively. After aeration the concentration of organic matters, T-N, T-P and BOD in the slurry were 2.01%, 4,400 mg/L, 420 mg/L and 16,824 mg/L, respectively. The concentration of organic matter, T-N, T-P and BOD in the mixing-in-pipe type changed from 1.58%, 3,700 mg/L, 260 mg/L and 15,735 mg/L to 1.96%, 4,000 mg/L, 340 mg/L, and 18,098 mg/L, respectively. Changes of the concentration of organic matter, T-N, T-P and BOD of the pig manure slurry collected from the middle layers of two aeration reactors; bottom aeration process and the mixing-in-pipe process, were 10.4%, 0%, 16.7% and 24.2% and 24.0%, 8.1%, 30.8% and 15.0%, respectively. The thickness of foam layer generated on the surface of pig manure slurry in aeration tank was thinner in mixing-in-pipe reactor than bottom-fixed type aeration reactor.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.507-517
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• 2008

There are considerable in vitro and in vivo evidences for remineralization and demineralization occurring simultaneously in incipient enamel caries. In order to "heal" the incipient dental caries, many experiments have been carried out to determine the optimal conditions for remineralization. It was shown that remineralization is affected by different pH, lactic acid concentrations, chemical composition of the enamel, fluoride concentrations, etc. Eighty specimens from sound permanent teeth without demineralization or cracks, 0.15 mm in thickness, were immersed in lactic acid buffered demineralization solutions for 3 days. Dental caries with a surface zone and subsurface lesion were artificially produced. Groups of 10 specimens were immersed for 10 or 12 days in lactic acid buffered remineralization solutions consisting of pH 4.3 or pH 6.0, and 100, 50, 25, or 10 mM lactic acid. After demineralization and remineralization, images were taken by polarizing microscopy (${\times}100$) and micro-computed tomography. The results were obtained by observing images of the specimens and the density of the caries lesions was determined. 1.As the lactic acid concentration of the remineralization solutions with pH 4.3 was higher, the surface zone of the carious enamel increased and an isotropic zone of the subsurface lesion was found. However, the total decalcification depth increased at the same time. 2.In the remineralization solutions with pH 6.0, only the surface zone increased slightly but there was no significant change in the total decalcification depth and subsurface zone. In the lactic acid buffer solutions with the lower pH and higher lactic acid concentration, there were dynamic changes at the deep area of the dental carious lesion.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.495-504
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• 2017

An amphibious scrubbing/suction dredging machine with cylindrical rotating brush, housing, and turbidity barrier was newly-developed to remove both sediments with about 10 cm thickness and periphyton attached on various structures in urban water-circulating systems through the scrubbing, suction, and dredging processes. Based on the field application and long-term monitoring, the increase in both suspended solids (SS) and turbidity of water during the scrubbing, suction, and dredging processes was negligible (p>0.05). In some cases, the turbidity of water initially increased, however, the turbidity was stabilized within 20 minutes from the start of dredging processes. The concentration changes in TN and TP of water were not statistically different (p>0.05) before and after the scrubbing, suction, and dredging processes, indicating that benthic nutrients released from sediments were not significantly diffused, and were not supposed to cause significant water pollution. Also, water treatment facilities along with an amphibious scrubbing/suction dredging machine could be more effective since the removal of contaminant loadings through the scrubbing, suction, and dredging processes was much greater than that through simple coagulation/precipitation processes. Finally, GPS-based realtime tracking and operation program have been developed and applied in various urban water-circulating systems, and development of driver cooperative autonomous driving system is in progress to eliminate the need for manual driving of an amphibious scrubbing/suction dredging machine.

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.98-109
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• 2007

Over the last twenty years, farmers in Western Australia have begun to change land management practices to minimise the effects of salinity to agricultural land. A farm plan is often used as a guide to implement changes. Most plans are based on minimal data and an understanding of only surface water flow. Thus farm plans do not effectively address the processes that lead to land salinisation. A project at Broomehill in the south-west of Western Australia applied an approach using a large suite of geospatial data that measured surface and subsurface characteristics of the regolith. In addition, other data were acquired, such as information about the climate and the agricultural history. Fundamental to the approach was the collection of airborne geophysical data over the study area. This included radiometric data reflecting soils, magnetic data reflecting bedrock geology, and SALTMAP electromagnetic data reflecting regolith thickness and conductivity. When interpreted, these datasets added paddock-scale information of geology and hydrogeology to the other datasets, in order to make on-farm and in-paddock decisions relating directly to the mechanisms driving the salinising process. The location and design of surface-water management structures such as grade banks and seepage interceptor banks was significantly influenced by the information derived from the airborne geophysical data. To evaluate the effectiveness ofthis planning., one whole-farm plan has been monitored by the Department of Agriculture and the farmer since 1996. The implemented plan shows a positive cost-benefit ratio, and the farm is now in the top 5% of farms in its regional productivity benchmarking group. The main influence of the airborne geophysical data on the farm plan was on the location of earthworks and revegetation proposals. There had to be a hydrological or hydrogeological justification, based on the site-specific data, for any infrastructure proposal. This approach reduced the spatial density of proposed works compared to other farm plans not guided by site-specific hydrogeological information.

• Journal of Radiation Protection and Research
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• v.38 no.2
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• pp.78-90
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• 2013

Recently, the interest on exposure to radiation is rising. The radiation exposure of mammography is higher in absorbed dose than of X-ray, therefore unnecessary exposure needs to be reduced, and higher image quality is needed. Generally, ray quality of the radiation imaging is an important factor that determines image quality and the amount of ray exposure, and they are affected by tube voltage and added filter. The X-ray energy that is exposed from mammography device is generally a continuous spectrum, which includes low energy that has minute influence on the image quality, and high energy that hinders contrast on image. Currently, molybdenum (Mo) and rhodium (Rh) are the most used added filters for mammography device, and they are used differently according to the energy region of X-ray. This study aims to find out the degree of reduction in exposure dose according to the thickness of aluminum (Al), and to study the changes in image quality and dose when the added filter plates that are made with niobium (Nb) or zirconium (Zr) are used, other than molybdenum (Mo) and rhodium (Rh), the two most used added filters that have similar atomic number and K-absorption regions as Nb and Zr. In this study, single-added filters of molybdenum (Mo), niobium (Nb), and zirconium (Zr) are used, and in some cases, Aluminum (Al) is combined with the single filters. In this case, image quality is considered to be improved depending on the type of added filters, and by using Aluminum (Al) filter together with the others, unnecessary X-ray of low energy would be absorbed, therefore the dose is expected to decrease without any influence when the concentration level becomes identical.