• The Journal of Korean Society for Radiation Therapy
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• v.23 no.2
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• pp.97-102
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• 2011

Purpose: IMRT QA using 2Dimensional array detector is carried out with condition for discrete dose distribution clinically. And it can affect uncertainty of evaluation using gamma method. We analyze gamma index variation according to grid size and suggest validate range of grid size for IMRT QA in Hospital. Materials and Methods: We performed QA using OniPro I'mRT system software version 1.7b on 10 patients (head and neck) for IMRT. The reference dose plane (grid size, 0.1 cm; location, [0, 0, 0]) from RTP was compared with the dose plane that has different grid size (0.1 cm, 0.5 cm, 1.0 cm, 2.0 cm, 4.0 cm) and different location (along Y-axis 0 cm, 0.2 cm, 0.5 cm, 1.0 cm). The gamma index variation was evaluated by observing the level of changes in Gamma pass rate, Average signal, Standard deviation for each case. Results: The average signal for each grid size showed difference levels of 0%, -0.19%, -0.04%, -0.46%, -8.32% and the standard deviation for each grid size showed difference levels of 0%, -0.30%, 1.24%, -0.70%, -7.99%. The gamma pass rate for each grid size showed difference levels of 0%, 0.27%, -1.43%, 5.32%, 5.60%. The gamma evaluation results according to distance in grid size range of 0.1 cm to 1.0 cm showed good agreement with reference condition (grid size 0.1 cm) within 1.5% and over 5% in case of the grid size was greater than 2.0 cm. Conclusion: We recognize that the grid size of gamma evaluation can make errors of IMRT QA. So we have to consider uncertainty of gamma evaluation according to the grid size and apply smaller than 2 cm grid size to reduce error and increase accuracy clinically.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.141-145
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• 2005

Purpose : It is known that the neutron is generally generated from the photon, its energy is larger than 10 MV. The neutron is leaked in the container inspection system installed at the customs though its energy is below 9 MV. It is needed that the spacial effect of the neutrons released from radiation treatment machine, linac, installed in the medical canter. Materials and Methods : The medical linear accelerator(Clinac 1800, varian, USA) was used in the experiment. Measuring neutron was used bubble detector(Bubble detector, BDPND type, BTI, Canada) which was created bubble by neutron. The bubble detector is located on the medical linear accelerator outskirt in three different distance, 30, 50, 120 cm and upper, lower four point from the iso-center. In addition, for effect on protect material we have measured eight points which are 50 cm distance from iso-center. The SAD(source-axis-distance), distance from photon source to iso-center, is adjusted to 100 cm and the field size is adjusted to $15{\times}15cm^2$. Irradiate 20 MU and calculate the dose rate in mrem/MU by measuring the number of bubble. Results : The neutron is more detected at 5 position in 30, 50 cm, 7 position in 120 cm and with wedge, and 2 position without mount. Conclusion : Though detection position is laid in the same distance in neutron measurement, the different value is shown in measuring results. Also, neutron dose is affected by the additional structure, the different value is obtained in each measurement positions. So, it is needed to measure and evaluate the neutron dose in the whole space considering the effect of the distance, angular distribution and additional structure.

• Pediatric Infection and Vaccine
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• v.7 no.1
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• pp.143-151
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• 2000

Purpose : The accuracy of bacteriologic diagnosis of beta-hemolytic streptococcal pharyngotonsillitis depends on the degree of carrier rate in that area where the throat swabs are obtained and the evaluation of serological T typing as an epidemiologic marker is important to understand epidemiology of streptococcal infection. The purpose of this study is to know the carrier rates of group A streptococcus in normal children form four different areas and to find out the epidemiologic characteristic in distribution of the serotypes for 3 years. Method : Throat swabs were obtained from the tonsillar fossa of normal school children in four different areas(Uljin, Seoul, Osan, Kunsan) from March to May 1996, in Uljin in April 1997, and in Uljin in April 1998. The samples were plated on a 5% sheep blood agar plate and incubated overnight at $37^{\circ}C$ before examination for the presence of beta-hemolytic colonies. All isolated beta-hemolytic streptococcus were grouped and serotyped by T agglutination. Results : The carrier rate of beta-hemolytic streptococci and group A streptococci in 1996 were 27.6%, 18.6% at Uljin; 16.4%, 2.7% at Seoul; 33.0%, 26.0% at Osan; 20.0%, 12.3% at Kunsan, respectively. Among 1,192 normal school children from 4 different areas, we obtained 179 strains of group A streptococci. Fifty two percent of the strains were typable by T agglutination in 1996. Common T-type in 1996 were NT, T1, T3, T2 at Uljin; T12, T25 at Seoul; NT, T6, T28 at Osan; T25, T4, NT, T5 at Kunsan, in decreasing order, respectively. At Uljin, T1, T3, T25 accounted for 69% of strains in 1996, T1, T12, T25 accounted for 70% in 1997, and T12, T4 accounted for 88% in 1998. Conclusion : Higher carrier rates were found in Uljin and Osan, where there are a lower population density with scanty of medical facilities compared with another areas. We supposed that low carrier rates is likely to be related to antibiotic abuse or some epidemiologic factor. The periodic and seasonal serotyping analysis is important in monitoring and understanding the epidemiologic patterns of group A streptococci.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.628-634
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• 2008

In recent years, cross-contamination has become one of the noticeable issues in dental clinic. Two major routes of contamination are the direct-contamination through blood and oral secretion and the indirect-contamination through dental office equipments. Especially, air-contamination through air-floating pollutant in a confined space like hospital, and also contamination through aerosol ejected from high-speed handpiece in a dental office was interested. The purpose of this study was to understand risk of bacterial infection through aerosol from handpiece in a dental office, which will help the practitioner with prevention of contamination during dental treatment. The main findings are as follows. 1. In a comparative test, the group using handpiece has higher bacterial number than the group not using handpiece with significant statistical difference(P<0.01). 2. The group using handpiece with rubber dam has lower bacterial number than the group using handpiecewithout rubber dam with significant statistical difference(P<0.01). 3. Comparing the group using drainage water with the group using distilled water as a handpiece water source results in 22.4 cfu and 17.0 cfu respectively but the difference is no statistically significant(P>0.05). 4. Measuring cfu at 0.5m and 1.5m distance, 0.5m distance showed higher bacterial number with statistical significance(P<0.01). 5. Classification of bacterial types showed the largest bacterial number came from gram-positive micrococcus(73.9%), and gram-negative micrococcus, gram-negative bacillus, and gram-positive bacillus follow in descending order.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.2
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• pp.160-168
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• 2000

Purpose: The purpose of this study was to evaluate the clinical and abdominal ultrasonogra- phic(US) features of spontaneously reduced transient small bowel intussusception in chlidren. Methods: We retrospectively reviewed the clinical and US findings of 98 children with intussusception who were admitted to the Pediatric Department of Ulsan Dong-Kang General Hospital from Mar. 1999 to Feb. 2000. Results: 1) Among 98 cases, there were 12 cases (12.3%) of transient small bowel intussusception(TSBI) and 86 cases (87.7%) of classic intussusception (CI). 2) The peak incidence of age in TSBI was over 3 years, which was older than that in CI. With regard to sex distribution, male predominated in both type. 3) Clinical symptoms and signs including cyclic irritability, vomiting, bloody stool, and abdominal mass in TSBI group were less common than those in CI group (41.7%, 33.4%, 0.0%, 0.0% vs 91.9%, 59.3%, 41.9%, 26.7%, respectively) but persistent abdominal pain was more common in TSBI group than in CI group (58.5% vs 11.2%). 4) The size of total target sign and surrounding peripheral hypoechoic rim of TSBI group on US were smaller than those of CI group ($11.95{\pm}2.61$ mm, $2.08{\pm}1.15$ mm vs $26.91{\pm}5.98$ mm, $7.86{\pm}2.77$ mm, respectively). 5) Concomittant illness was found more frequently in TSBI group than in CI group (66.7% vs 26.7%). 6) All case of TSBI group were reduced spontaneouly, which were confirmed by US, but none of CI group. Conclusion: Transient small bowel intussusception is probably more common than generally thought and its clinical and US findings is quite different from classical obstructing intussus-ception. Because all of our cases resulted in spontaneous reduction, we recommend careful observation and repeat examination rather than an immediate operation in transient small bowel intussusception.

• Pediatric Infection and Vaccine
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• v.15 no.2
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• pp.121-128
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• 2008

Purpose : The seasonality of influenza virus and rotavirus are well recognized in winter and so viral surveillance and laboratory-based diagnostics are important to guide the timing of prophylaxis and other interventions. Yet the seasonality of these two viruses are changing in Korea. We evaluated the prevalence and clinical features of influenza virus and rotavirus. Methods : From September 2001 to August 2005, nasopharyngeal aspirates were cultured from the hospitalized patients with lower respiratory infections and the stools from hospitalized patients with gastroenteritis were tested for rotavirus. We retrospectively analysed the medical records. Results : During the study period, respiratory virus was isolated in 578 (18.5%) out of 3,121 patients. Influenza virus was isolated in 143 cases. The seasonal distribution of influenza infection was from December to June of the next year. The ratio of males to females was 1.3:1 and the median age was 17 months. The most common diagnosis of influenza infection was bronchiolitis. Fever and cough were present in 94.4% and 83.9% of the patients, respectively. During the same period, 3,850 patients were admitted for gastroenteritis and 1,047 (27%) patients were positive for rotavirus. Rotavirus was prevailed from December to June of the next year and it presented in year-round. The ratio of males to females was 1.1:1 and the median age was 16 months. Diarrhea and vomiting were the most common symptoms. Conclusion : The recent peak prevalence of influenza virus and rotavirus in Korea was in winter and the late spring, respectively. So we need to expand surveillance and carefully consider the correct period to vaccinate people.

• Childhood Kidney Diseases
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• v.15 no.2
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• pp.138-145
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• 2011

Purpose : To test whether the expression of ${\beta}$-catenin, a component of podocyte as a filtration molecule, would be altered by puromycin aminonucleoside (PAN) in the cultured podocyte in vitro. Methods : We cultured rat glomerular epithelial cells (GEpC) with various concentrations of PAN and examined the distribution of ${\beta}$-catenin by confocal microscope and measured the change of ${\beta}$-catenin expression by Western blotting and reverse transcriptase-polymerase chain reaction (RT-PCR). Results :We found that ${\beta}$-catenin relocalized from peripheral cytoplasm to inner cytoplasm, therefore, intercellular separations were seen in confluently cultured cells by high concentrations of PAN in immunofluorescence views. In Western blotting of GEpC, PAN ($50{\mu}g/mL$) decreased ${\beta}$-catenin expression by 34.9% at 24 hrs and 34.3% at 48 hrs, compared to those in without PAN condition (P<0.05). In RT-PCR, high concentrations ($50{\mu}g/mL$) of PAN also decreased ${\beta}$-catenin mRNA expression similar to protein suppression by 25.4% at 24 hrs and 51.8% at 48 hrs (P<0.05). Conclusion : Exposure of podocytes to PAN in vitro relocates ${\beta}$-catenin internally and reduces ${\beta}$-catenin mRNA and protein expression, which could explain the development of proteinuria in experimental PAN-induced nephropathy.

• The Korean Journal of Nuclear Medicine
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• v.37 no.2
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• pp.94-102
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• 2003

Purpose : Cerebral blood flow (CBF) reactivity to acetazolamide (ACZ) is useful to select patients with hemodynamic failure. However, it is still a matter of speculation that varying degrees of regional CBF increases after ACZ administration represent the severity or stage of regional hemodynamic failure as assessed by positron emission tomography (PET). We studied to elucidate whether ACZ challenge $^{123}I-IMP$ brain single photon emission tomography (SPECT) can accurately grade the seventy of regional hemodynamic failure. Materials and Methods: Eighteen patients (M: 16, F: 2, average age: 61 years) with unilateral occlusive disease of the internal carotid artery or the trunk of the middle cerebral artery (MCA). Patients undewent $^{123}I-IMP$ brain SPECT study with acetazolamide challenge and PET study was carried out within 2 weeks before and after SPECT study. Five healthy volunteers with a mean age of 48 years (range: 28-73 yr, M: 3, F: 2) underwent PET studies to determine normal values. In SPECT study, an asymmetry index (Al)-the percentage of radioactivity of region of interest (ROI) in the occlusive cerebrovascular lesion to the contralateral homologous ROI-was used for numerical evaluation of relative $^{123}I-IMP$ distribution. In PET study, regional CBF, oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen ($CMRO_2$) and cerebral blood volume (CBV) values were measured with $^{15}O-labeled$ gas inhalation method and the values were used for comparison with Al (Al during acetazolamide challenge-Al of basal study) on the SPECT study. ROls were classified by severity into three groups (normal, stage I and stage II). Results: Mean values of Al in areas with normal, stage I and stage II hemodynamic failure were $6.25{\pm}7.77%\;(n=107),\;-10.38{\pm}10.41%\:(n=117)\;and\;13.30{\pm}10.51%\;(n=140)$, respectively. Al significantly differed with each groups (p<0.05). Correlation between Al and CBF, OEF and CBV/CBF in hemisphere with occlusive cerebrovascular lesion was 0.20 (p<0.01), -0.28 (p<0.01) and -0.28 (p<0.01), respectively. Conclusion: We concluded that $^{123}I-IMP$ brain SPECT with acetazolamide challenge could determine the severity ad stage of regional hemodynamic failure as assessed by PET.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.2
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• pp.9-25
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• 2020

In 2010 and 2015, total 77 surface sediment samples were collected to assess the anthropogenic effects of trace metals in surface sediments of Garolim Bay, and the physical characteristics (particle size and specific surface area) and geochemical components (major (Al, Ca, Fe, K, Ba) and trace metals (Mn, Cs, Cr, Co, Ni, Cu, Zn, Pb), organic carbon and calcium carbonate) were analyzed. Mean grain size of Garolim Bay surface sediments ranged from 0.51-5.58 Ø (mean 3.98 Ø) and increased from the inlet of bay to the inner bay, and from the waterway to the land. Most of the metal concentrations except for some elements showed the similar distribution to those of mean grain size and specific surface area. As the particle size decreased and the specific surface area increased, the metal concentration increased. In order to estimate the factors controlling the concentration of trace metals, factor analysis was performed, and three factors were extracted (92.7% of the total variation). Factor 1 accounted for 71.3% of the total variation, which was a grain size factor. Factor 2 accounted for 14.2% of the total variation, Factor 3 accounted for 7.2% of the total variance. Enrichment factor was calculated using the particle size corrected background concentration. Metals with a enrichment factor of 1.5 or higher and the number of samples were 4 for Cr (St. 1, 16, 27, 39) and 1 for Pb (St. 39), but there were little differences in the concentrations of 1M HCl leached metals for these metals. The percentage of 1M HCl leached fraction to total metal concentration decreased in the order of Pb~Co>Cu>Zn~Mn>Ni>Cr. Comparing this value with contaminated and clean sediments in other coastal areas, the percentages for each metal were similar regardless of the trace metal levels in all regions. This fact might be resulted from the reaction between the 1M HCl solution and the different sediment constituents, indicating that there is a limit to apply this percentage of leached metal to the estimation of the contamination extent.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.2
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• pp.202-212
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• 2005

Purpose: Transfusion transmitted virus (TTV) is a newly discovered virus and to date the contribution of TTV to liver disease remains unclear. Little is known about the frequency of TTV infection in children in Korea. The purpose of this study was to investigate the prevalence and genotypic distribution of TTV carried by healthy children and patients with hepatitis in Korea. Methods: Eighty eight of healthy children and three groups of patients with hepatitis-14 patients with chronic hepatitis B, 12 patients with chronic hepatitis C and 25 patients with hepatitis of unknown etiology-were tested. TTV DNA was detected by semi-nested PCR using primer sets generated from N-22 region and from 5' noncoding region (NCR) of the viral genome. PCR products derived from 8 patients with hepatitis and from 11 healthy children were sequenced and a phylogenetic tree was constructed. Results: TTV was found by PCR with N22 primer in 11.3% of healthy children, 28.5% of children with hepatitis B, 25% of children with hepatitis C, 24% of children with hepatitis of unknown etiology. TTV DNA was found by PCR with 5'NCR primer in 32.9% of healthy children, 71.4% of patients with chronic hepatitis B, in 50% of patients with hepatitis C and in 48% of patients with hepatitis of unknown etiology. TLMV DNA was found in 48.9% of healthy children, 21.4% of patients with hepatitis B, 16.6% of patients with hepatitis C, 40% of patients with hepatitis of unknown etiology. Among the sequenced isolates, 10(52%) belonged to genotype 1 (G1) and others belonged to genotype 2 (G2) or genotype 3 (G3). Among the G1 sequences, 7 were grouped as G1a. Conclusion: TTV infection was common in healthy children and in patients with hepatitis. But, the prevalence of TTV DNA by 5'NCR primer was relatively high in patients with hepatitis B and there may be some association between TTV and hepatitis B virus infection. G1 was the major genotype of the studied population.