• Progress in Medical Physics
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• v.23 no.4
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• pp.252-260
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• 2012

The reduction of radiation dose from x-ray is a main concern in computed tomography (CT) imaging due to the side-effect of the dose on human body. Recently, the various methods for dose reduction have been studied in CT and one of the method is a iterative reconstruction based on total variation (TV) minimization at few-views data. In this paper, we evaluated the image quality between total variation (TV) minimization algorithm and Feldkam-Davis-kress (FDK) algorithm in micro computed tomography (CT). To evaluate the effect of TV minimization algorithm, we produced a cylindrical phantom including contrast media, water, air inserts. We can acquire maximum 400 projection views per rotation of the x-ray tube and detector. 20, 50, 90, 180 projection data were chosen for evaluating the level of image restoration by TV minimization. The phantom and mouse image reconstructed with FDK algorithm at 400 projection data used as a reference image for comparing with TV minimization and FDK algorithm at few-views. Contrast-to-noise ratio (CNR), Universal quality index (UQI) were used as a image evaluation metric. When projection data are not insufficient, our results show that the image quality of reconstructed with TV minimization is similar to reconstructed image with FDK at 400 view. In the cylindrical phantom study, the CNR of TV image was 5.86, FDK image was 5.65 and FDK-reference was 5.98 at 90-views. The CNR of TV image 0.21 higher than FDK image CNR at 90-views. UQI of TV image was 0.99 and FDK image was 0.81 at 90-views. where, the number of projection is 90, the UQI of TV image 0.18 higher than FDK image at 90-views. In the mouse study UQI of TV image was 0.91, FDK was 0.83 at 90-views. the UQI of TV image 0.08 higher than FDK image at 90-views. In cylindrical phantom image and mouse image study, TV minimization algorithm shows the best performance in artifact reduction and preserving edges at few view data. Therefore, TV minimization can potentially be expected to reduce patient dose in clinics.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.52-68
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• 1991

A new propeller series is developed using the newly developed blade section(KH18 section) which behaves better cavitation characteristics and higher lift-drag ratio at wide range of angle-of-attack. The pitch and camber distributions are disigned in order to have the same radial and chordwise loading distribution with the selected circumferentially averaged wake input. Since the geometries of the series propeller, such as chord length, thickness, skew and rate distribations, are selected by regression of the recent full scale propeller geometric data, the performance prediction of a propeller at preliminary design stage can be mure realistic. Number of blades of the series propellers is 4 and the expanded blade area ratios are 0.3, 0.45, 0.6 and 0.75. Mean pitch ratios are selected as 0.5, 0.65, 0.8, 0.75 and 1.1 for each expanded area ratio. The new propeller series is composed of 20 propellers and is named as KD(KRISO-DAEWOO) propeller series. Propeller open water tests are performed at the experimental towing tank, and the cavitation observation tests and fluctuating pressure measurements are carried out at the cavitation tunnel of KRISO. $B_{P}-\delta$ curves, which can be used to select the optimum propeller diameter at the preliminary design stage, are derived from a regression analysis of the propeller often water test results. The KD-cavitation chart is derived from the cavitation observation test results by choosing the local maximum lift coefficient and the local cavitation number as parameters. The caviy extent of a propeller can be predicted more accurately by using the KD-cavitation chart at a preliminary design stage, since it is derived from the results of the cavitation observation tests in the selected ship's wake, whereas the existing cavitation charts, such as the Burrill's cavitation chart, are derived from the test results in uniform flow.

• Food Science and Preservation
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• v.20 no.4
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• pp.564-572
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• 2013

We investigated the quality characteristics of brewing brown rice vinegar through a traditional static fermentation process. Accordingly, we decided to compare the physicochemical characteristics of brewing vinegar at different temperatures and filtration methods. In four to five weeks' time, the acetic acid fermentation exhibited the highest titratable acidity and then it eventually decreased. The titratable acidity was affected by the filtration method. It was revealed that the titratable acidity was higher in the forced filtration than the traditional filtration method. Various organic acids were detected in order to initialize the fermentation stage and as the fermentation progressed, only the acetic acid could be detected. The total free amino acid content was higher at a temperature of $30^{\circ}C$ than at $20^{\circ}C$. Moreover, the free amino acid content was dependent on the acetate content during the acetic fermentation process. The main bioactive substance of the ${\gamma}$-aminobutyric acid content was more than twice at a fermentation temperature of $30^{\circ}C$ compared to the fermentation temperature of $20^{\circ}C$. Furthermore, the total amino acid and essential amino acid content at a temperature of $30^{\circ}C$ was excellent. The quality of the brown rice vinegar via forced filtration method at a temperature of $30^{\circ}C$ was the most excellent. Based on these results, the fermentation temperature and the use of nuruks (fermenting agent) affected the quality of the brown rice vinegar, and an appropriate method to consider its purpose is required.

• Journal of dental hygiene science
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• v.2 no.2
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• pp.89-94
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• 2002

The present study attempts to find the ways to efficiently manage dental caries, one of the major causes of tooth loss, and to cope with oral diseases that deteriorate oral health. For this purpose, this study seeks to obtain fundamental data needed in planning the oral health projects. The study was conducted to the first-grade elementary school students in Hwa-Seong city, Gyeonggi-do, from April 1 - 30, 2002. The result was as follows: 1) Among a total of 2,710 subjects, 598 (274 boys and 324 girls) have more than 1 permanent tooth with a caries legion whether it was treated or not. 2) The number of permanent teeth examined is 6,029, in which girls' teeth are more (3,165) than boys' (2,864). 3) Out of a total of 6,029 teeth examined, 1,106 permanent teeth (508 boys' and 598 girls') have caries legions. 4) Out of 1,106 permanent teeth with caries legions, 170 (15.4%) were treated - 67 teeth for boys (13.2%) and 103 teeth for girls (17.2%). 5) 22.1% of the children have experienced dental caries in their permanent teeth. Among them, 20.1% are boys and 24.1% are girls. 6) The rate of the permanent teeth that once had, or now have caries legions are 21.2%, among which the rate for boy's teeth is 20.1% and that for girl's teeth is 22.1%. 7) The number of the permanent teeth that had caries legions is 0.5 for all the subjects. A boy has 0.4 and a girl has 0.5 teeth with caries legions regardless of whether it was treated or not. 8) The rate of the permanent teeth with caries legions is 86.7% for overall subjects - 88.3% for boys and 85.3% for girls. 9) The rate of treated permanent teeth is 13.3% for all the subjects - 11.7% for boys and 14.7% for girls. Based on the above result, the study draws a conclusion that in order to prevent dental caries in young students and to perform an early treatment for the dental caries that already occurred an oral health office should be installed at all the elementary schools so that elementary school students don't experience a loss of time and effort for learning and suffer nutritional imbalance or disorder. Besides, the oral health education concerning the importance of dental care should be conducted to the citizens, especially to the young people, in the community as an essential project of oral health centers in the community health offices, the public medical institutions.

• Korean Journal of Agricultural Science
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• v.26 no.2
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• pp.39-48
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• 1999

This study was carried out to investigate the difference and genetic similarity at the level of molecular genetics. Genomic DNA was extracted from blood of Holstein, Korean cattle, Charolais, and hybrid between Korean cattle and charolais and RAPD(random amplified polymorphic DNAs) was analyzed by PCR(polymerase chain reaction). After genetic similarity value from different breeds are analyzed, genetic similarity was estimated by UPGMA(unweighted pair-group method using average). The results obtained from this study can be summarized as follows: 1. When genomic DNA which was extracted from different breeds was subjected to electrophoresis on 1.5% agarose gel, bigger than 12.2kb was appeared. Ratio by absorbance of $A_{260}/A_{280}$ was 1.75~2.10, indicating that genomic DNA was quite pure for RAPD analysis. 2. Different band patterns by RAPD were appeared according to the breeds in cattle. The best primer used to distinguish Holstein from other breeds was 5'-GAC CGC TTG T-3'. 3. A 340bp fragment was amplified in $33.0^{\circ}C$ of annealing temperature for the Holstein and Charolais breeds, but any amplification was not occurred in this annealing temperature for Korean cattle and hybrid. In addition, a 340bp fragment was amplified in $37.5^{\circ}C$ of annealing temperature for the Holstein and Korean cattle, but any amplification was not occurred in this annealing temperature for Charolais and hybrid. For the reaction of PCR. $37.5^{\circ}C$ and $33.0^{\circ}C$ of annealing temperature was shown to be best for genetic marker identification from Holstein, Charolais, and hybrid between Korean cattle and Charolais. 4. When genetic similarity from different breeds are analyzed at the both temperature of $33.0^{\circ}C$ and $37.5^{\circ}C$, the genetic similarity value of Holstein and Korean cattle, Holstein and Charolais, Korean cattle and Charolais, and Korean cattle and hybrid were 0.666~0.777, 0.615~0.666, 0.400~0.461 and 0.857~0.888, respectively. 5. It could be concluded that different breeds are capable of distinguishing by RAPD used random primer 5'-GAC CGC TTG T-3', genetic similarity from different breeds was appeared the higher genetic similarity value of Korean cattle and Charolais than that of Holstein between Korean cattle and Charolais by UPGMA.

• Tuberculosis and Respiratory Diseases
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• v.49 no.6
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• pp.733-739
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• 2000

Background : Pleural eosinophilia is rare and commonly considered to be an indicator of good prognosis. The diagnostic significance of eosinophilic pleural effusions remains controversial despite a century of observation and discussion. This study was conducted to assess the prevalence of eosinophilia in 446 consecutive samples of pleural fluid, to review the cause of eosinophilic pleural effusion and to determine whether the presence of eosinophils increases the likehood of benign conditions. Method : A retrospective analysis was performed upon patients that underwent first thoracentesis due to pleural effusion between January 1999 and December 1999. Results : Eosinophilic pleural effusions were identified in 24 of the 446 patients (5.4%). Malignancy, parapneumonic effusion and tuberculosis were determined the major causes of pleural effusion (80.6%). Malignancy was diagnosed as frequently in eosinophilic effusions as in non-eosinophilic effusions (54.2% vs 50.5%, p=0.725). No difference was found in the prevalence of eosinophilic and non-eosinophilic effusion according to the etiology. The mean blood eosinophil ratio in patients with eosinophilic pleural effusion was 5.4% and no significant correlation existed between the blood and pleural eosinophilic count. Conclusion : Pleural eosinophilia is not helpful for differentiating benign and malignant etiology and is not related with bood eosinophilia or repeated tapping.

• Tuberculosis and Respiratory Diseases
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• v.49 no.6
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• pp.676-683
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• 2000

Background : Surgery may have a role when medical treatment alone is not successful in patients with multidrug resistant (MDR) pulmonary tuberculosis (PTB). To document the role of resection in MDR PTB, we analyzed 4 years of our experience. Methods : A retrospective review was performed on thirteen patients that underwent pulmonary resection for MDR PTB between May 1996 and February 2000. All patients had organisms resistant to many of the first-line drugs including isoniazid (INH) and rifampicin (RFP). Results : The thirteen patients were $37.5{\pm}12.4$ years old (mean${\pm}$S.D.)(M : F=5:8), and their sputum was culture positive even with adequate medication for prolonged periods ($109.7{\pm}132.0$ months), resistant to 2-8 drugs including isoniazid and rifampin. All patients had localized lesion(s) and most (92.3%) had cavities. At least 3 sensitive anti-TB medications were started before surgery in all patients according to the drug sensitivity test. The preoperative $FEV_1$ was $2.37{\pm}0.83$ L. Lobectomy was performed in 11 patients and pleuropneumonectomy in two. Postoperative mortality did not occur, but pneumonia occurred as a complication in one (7.7%). After $41.5{\pm}58.9$ days (range 1~150 days) follow up, negative conversion of sputum culture was achieved in all patients within 5 months. Only one patient (7.7%) recurred 32 months after lung resection. Conclusion : When medical treatment alone is not successful, surgical resection can be a good treatment option in patients with localized MDR PTB.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.35-43
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• 2010

We have developed a sodium fluoride containing gelatin and methyl cellulose gel. Cariostatic abilities of those gel were investigated and compared with APF gel and fluoride varnish($Cavityshield^{TM}$). We prepared the bovine tooth samples and divided into two surface, control side and experimental side in same specimen for exclusion of difference between specimens. The experiment was consisted of 4 groups : (I) APF gel : (II) $Cavityshield^{TM}$ : (III) Gelatin F gel : (IV) Methyl cellulose F gel Decalcification were produced by placing each specimen into artificial acidic solution(pH 4.0) for 72 hours. Surface microhardness were measured and depth of demineralization lesion were measured by polarizing light microscope. The results were as follows: 1. The difference of VHN between control and experimental side is smallest in group I (p<0.05). 2. The largest difference was shown in group II (p<0.05). 3. There were no significant difference between group III and IV in microhardness test (p>0.05). 4. The difference of lesion depth is smallest in group I (p<0.05). 5. There were no significant difference between group II, III and IV in lesion depth (p>0.05). The result of the present study indicate that the fluoride containing gelatin and methyl cellulose gel is more effective than APF gel and is similar to fluoride varnish application for prevention of demineralization.

• Journal of the Korean Magnetics Society
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• v.27 no.2
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• pp.41-48
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• 2017

Recent study shows that ordered alloy of $L1_2$ $XPt_3$ (M = V, Cr, Mn, Co, and Fe) exhibits various magnetic phases such as ferromagnetic-to-antiferromagnetic transition at the $MnPt_3$ surface. Moreover, it has been argued that $CrPt_3$, in particular, possess large magnetocrystalline anisotropy and Kerr rotation with possible violation of Hund's rule. As such, we extend our work to thickness dependence of the magnetic structure of $CrPt_3$ thin film using density functional theory. Magnetic ground state of the bulk $CrPt_3$ turns out to be ferromagnetic (FM), where other magnetic phases such as A-type (A-AF), C-type (C-AF), and G-type antiferromagnetic (G-AF) state have higher total energies than FM by 0.517, 0.591, and 0.183 eV, respectively, and magnetic moments of Cr in bulk are respectively 2.807 (FM), 2.805 (A-AF), 2.794 (C-AF) and $2.869_{{\mu}_B}$ (G-AF). We extend our study to $CrPt_3$(001) thin films with CrPt-and Pt-termination. The thickness and surface-termination dependences of magnetism are investigated for 3-9 monolayers (ML), where different magnetic phases from bulk emerge: C-AF for CrPt-terminated 3 ML and G-AF for Pt-terminated 5 ML have energy difference relative to FM by 8 and 54 meV, respectively. Furthermore, thickness- and surface-termination-dependent magnetocrystalline anisotropies of the $CrPt_3$(001) films are discussed.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.4
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• pp.239-252
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• 2007

Objectives: In the present study, we examined the differentiation potential of human adipose-(HAD) and human umbilical cord-derived mesenchymal like stem cells (HUC) into cardiomyocytes. Methods: Cells were initially exposed to 5-azacytidine for 24h cells and then were cultivated in the presence or absence of activin A, TGF-$\beta$1, or Wnt inhibitor with various combinations of BMP and FGF. Assessment of cardiomyogenic differentiation was made upon the expression of cardiomyocyte-specific genes using RT-PCR. Results: HAD that cultivated in control medium for 4 weeks after 5-azacytidine expose showed new expression of TnT gene and increased expression of Cmlc1 and kv4.3 genes. However, HAD cultivated in the presence of combinations of BMP-4/FGF-4 (B4/F4) and BMP-4/FGF-8 (B4/F8) showed new expression of $\beta$-MHC gene and more increased expression of Cmlc1, TnT, TnI, Kv4.3 genes. Significantly enhanced expression of Cmlc1, TnT, and Kv4.3 genes were also observed compared to that cultivated in the control medium. Treatment of HUC with either 5-azacytidine or combinations of BMP and FGF did not affect the expression profile of these genes. However, when activin A or TGF-$\beta$1 was present in addition to the BMP-2/FGF-8 (B2/F8) after 5-azacytidine exposure, HUC exhibited new expression of $\beta$-MHC gene and increased expression of $\alpha$-CA, TnT and Kv4.3 genes. When Wnt inhibitor was present in addition to BMP and FGF, HUC showed new expression of Cmlc1 gene and increased expression of $\alpha$-CA, TnT, TnI and Kv4.3 genes. Conclusions: Based on these observations, it is suggested that HAD and HUC could differentiate into cardiomyocytes which might be used as therapeutic cells for the heart diseases.