• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.23-30
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• 2018

To evaluate the effect of patient size on effective dose and image quality for Digital Chest Tomosynthesis(DTS) using additional 0.3 mm copper filtration. Eighty artificial nodules were placed in the thorax phantom("Lungman," Kyoto Kagaku, Japan), and Digital Chest Tomosynthesis(DTS) images of the phantom were acquired both with and without added 0.3 mm Cu filtration. To simulate patients of three sizes: small, average size and oversize, one or two 20-mm-thick layer of PMMA(polymethyl methacrylatek) blocks were placed on the phantom. The Effective dose was calculated using Monte Carlo simulations. Two evaluations of image quality methods have been employed. Three readers counted the number of nodules detected in the lung, and the measured contrast-to-noise ratios(CNRs) were used. Data were analyzed statistically. The ED reduced $26{\mu}Sv$ in a phantom, $33{\mu}Sv$ in one 20-mm-thick layer of PMMA block placed on the phantom, and $48{\mu}Sv$ in two 20-mm-thick layer of PMMA blocks placed on the phantom. The Effective dose(ED) differences between DTS with and without filtration were significant(p<0.05). In particular, when we used two 20-mm-thick layer of PMMA blocks placed on the phantom, the ED was significantly reduced by 36% compared with those without additional filtration. Nodule detection sensitivities were not different between with and without added filtration. Differences of CNRs were statistically insignificant(p>0.05). Use of additional filtration allows a considerable dose reduction during Digital Chest Tomosynthesis(DTS) without loss of image quality. In particular, additional filtration showed outstanding result for effective dose reduction on two 20-mm-thick layer of PMMA blocks placed on the phantom. It applies to overweight patients.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.563-575
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• 2020

The purpose of this study is to evaluate the activation characteristics that occur in a linear accelerator for container security inspection. In the computer simulation design, first, the targets consisted of a tungsten (Z=74) single material target and a tungsten (Z=74) and copper (Z=29) composite target. Second, the fan beam collimator was composed of a single material of lead (Z=82) and a composite material of tungsten (Z-74) and lead (Z=82) depending on the material. Final, the concrete in the room where the linear accelerator was located contained magnetite type and impurities. In the research method, first, the optical neutron flux was calculated using the MCNP6 code as a F4 Tally for the linear accelerator and structure. Second, the photoneutron flux calculated from the MCNP6 code was applied to FISPACT-II to evaluate the activation product. Final, the decommissioning evaluation was conducted through the specific activity of the activation product. As a result, first, it was the most common in photoneutron targets, followed by a collimator and a concrete 10 cm deep. Second, activation products were produced as by-products of W-181 in tungsten targets and collimator, and Co-60, Ni-63, Cs-134, Eu-152, Eu-154 nuclides in impurity-containing concrete. Final, it was found that the tungsten target satisfies the permissible concentration for self-disposal after 90 days upon decommissioning. These results could be confirmed that the photoneutron yield and degree of activation at 9 MeV energy were insignificant. However, it is thought that W-181 generated from the tungsten target and collimator of the linear accelerator may affect the exposure when disassembled for repair. Therefore, this study presents basic data on the management of activated parts of a linear accelerator for container security inspection. In addition, When decommissioning the linear accelerator for container security inspection, it is expected that it can be used to prove the standard that permissible concentration of self-disposal.

• Pediatric Infection and Vaccine
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• v.6 no.1
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• pp.86-92
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• 1999

Purpose : The purpose of this study is to know the epidemiology and clinical characteristics in patients with M. pneumoniae pneumonia during study period retrospectively. Methods : We had reviewed 500 patients with Mycoplasma pneumoniae pneumonia who were hospitalized at the pediatric ward of Seoul Adventist Hospital from July 1986 through June 1996. we had analysed clinical and laboratory problems of pulmonary and extrapulmonary manifestations including demographics and epidemiological characteristics. Results : Peak occurrence of the disease was 3 years interval and seasonal occurrence of the disease had no difference. 43.4% of patients was below 4 years old and male to female ratio was nearly 1:1. The most common site of infiltration on chest PA was right lower lobe and the most common type of pneumonia was interstitial pneumonia(43%). Pulmonary complications were atelectasis(11cases), emphysema(5cases), pleural effusion(27cases) and sinusitis(13cases) and extrapulmonary manifestations were hepatitis(109cases), skin rash(29cases), proteinuria(20cases) and hematuria(16cases). cold agglutinin test was carried out in 500cases and mycoplasma antibody test was carried out in 448cases. sensitivity of mycoplasma antibody test was 53.3%. Conclusion : Mycoplasma pneumoniae pneumonia showed epidemics at intervals of 3 year in its major occurrence. it exhibits a tendency that occurs at younger age group not in school age group. diagnosis of the disease need more accurate method due to low sensitivity of mycoplasma antibody test. also we need to carried out other laboratory test(for example, LFT, U/A).

• Tuberculosis and Respiratory Diseases
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• v.65 no.6
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• pp.495-503
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• 2008

Background: Epigenetic alterations in certain genes are now known as at least important as genetic mutation in pathogenesis of cancer. Especially abnormal hypermethylation in or near promoter region of tumor suppressor genes (TSGs) are known to result in gene silencing and loss of gene function eventually. The authors tried to search for new lung cancer-specific TSGs which have CpG islands and HpaII sites, and are thought to be involved in carcinogenesis by epigenetic mechanism. Methods: Tumor tissue and corresponding adjacent normal tissue were obtained from 10 patients who diagnosed with non small cell lung cancer (NSCLC) and underwent surgery in Konyang university hospital in 2005. Methylation profiles of promoter region of 21 genes in tumor tissue & non-tumor tissue were examined with HpaII-MspI methylation microarray (Methyl-Scan DNA chip$^{(R)}$, Genomic tree, Inc, South Korea). The rates of hypermethylation were compared in tumor and non-tumor group, and as a normal control, we obtained lung tissue from two young patients with pneumothorax during bullectomies, methylation profiles were examined in the same way. Results: Among the 21 genes, 10 genes were commonly methylated in tumor, non-tumor, and control group. The 6 genes of APC, AR, RAR-b, HTR1B, EPHA3, and CFTR, among the rest of 11 genes were not methylated in control, and more frequently hypermethylated in tumor tissue than non-tumor tissue. Conclusion: In the present study, HTR1B, EPHA3, and CFTR are suggested as possible novel TSGs of NSCLC by epigenetic mechanism.

• Journal of the Korean earth science society
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• v.36 no.7
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• pp.661-673
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• 2015

UBVI CCD photometry of the intermediate age open cluster NGC 7790 has been obtained using AZT-22 1.5 m telescope (f/7.74) at the Maidanak Astronomical Observatory in Uzbekistan. NGC 7790 contains three ${\delta}$ Cep variable stars including CEa Cas, CEb Cas, and CF Cas. PSF photometry was carried out using IRAF/DAOPHOT for all observations. The total number of stars observed both in V and I filter was 1008 and the limiting magnitude was $V{\approx}22$. To determine atmospheric extinction coefficients and photometric zero points, many blue and red standard stars as well as the standard stars in the celestial equator under various airmass were observed. Photometric data were transformed into the standard Johnson-Cousins' UBVI standard system. From the analysis of UBVI color-magnitude diagram and color-color diagram, the color excess in V and I filter [$E(B-V)=0.58{\pm}0.02$], the selective extinction ratio in V and I filter [$R_V{\equiv}A_V/E(B-V)=3.02{\pm}0.09$] and distance modulus ($V_0-M_V=12.65{\pm}0.10$) of the cluster were determined. The age of the cluster was estimated to be log $age=8.05{\pm}0.05$ [yr] based on the position of these three Cepheid variables in the color-magnitude diagram, the isochrone of the Geneva group ($Ekstr{\ddot{o}}m$ et al., 2012-Z=0.019), and the isochrone of the Padova group (Bressan et al., 2012-Z=0.014) were used to compare each other. Of them, the Geneva models that considered stellar rotation well described the position of ${\delta}$ Cepheid variables in the blue loop. Although they were well consistent with standard period-luminosity relation of ${\delta}$ Cepheid variables, three Cepheid variables in NGC 7790 were, on average, brighter by about 0.5 mag than the absolute magnitude estimated from the mean period-luminosity relation at a given period.

• KSBB Journal
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• v.14 no.3
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• pp.309-314
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• 1999

In order to produce high concentration of sodium gluconate, optimization of the fermentation conditions, such as glucose concentration, inoculum size, dissolved oxygen concentration and glucose feeding method, was examined. When the glucose concentration was maintained in the range of 30∼50 g/L during the batch fermentation, glucose conversion yield and productivity were 92.2% and 6.0 g/L/hr, respectively. In the case of the low concentration below 30 g/L, the yield decreased by about 25%. As the inoculum size increased above 20%(w/v), lag phase was shortened but the productivity decreased. The dissolved oxygen level of 60∼70% was shown to be the threshold point for 75% of increase in the productivity of sodium gluconate. Finally, optimal glucose feeding rate was determined using various feeding methods such as exponential feeding, feeding based on the average glucose consumption rate and was determined using various feeding methods such as exponential feeding, feeding based on the average glucose consumption rate and on the oxygen uptake rate and etc. Our result shows that glucose feeding, based on the oxygen uptake rate is a very simple, efficient and robust method, especially when oxygen is consumed as a substrate for the bioconversion. Using the above glucose feeding strategy under the optimized condition, 255 g/L of sodium gluconate concentration, 12 g/L/hr of productivity and 95% of glucose conversion yield were achieved with A. niger ACM53.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.89-95
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• 2007

This study was carried out to evaluate soil properties by regions from chestnut (Castanea crenata Sieb. et Zucc) stands in Gyeongnam province. Soil physical and chemical properties were measured from soil samples of top 20 em collected from three hillslopes (upper, middle, lower) of the chestnut stands in six regions (Jinjusi, Sacheonsi, Sancheonggun, Hadonggun, Goseonggun, Hapcheongun) where are major chestnut cultivation areas throughout the province. Soil properties were significantly different among regions (p<0.05), while were not significantly different among hillslopes (p>0.05). Soil bulk density, soil pore space, soil pH, organic matter content, total nitrogen, available phosphorus, and CEC were significantly different among regions (p<0.05). Soil bulk density was significantly lower (p<0.05) in Hadonggun ($0.96g/cm^3$ than in other regions ($1.12{\sim}1.22g/cm^3$). Soil pH was below pH 5.03 in most regions and Sancheonggun showed the lowest soil pH value (pH 4.62), followed by Jinjusi, Hadonggun, Hapcheongtm, Goseonggun, and Sacheonsi. Organic matter content was highest in Hadonggun (6.46%), while other regions ranged between 2.93% and 3.47%. Total nitrogen content showed a similar trend like the organic matter content. Available phosphorus was above 100 ppm in Jinjusi, Hadonggun and Sancheonggun, but Sacheonsi showed the lowest concentration (15 ppm) among the regions. Cation Exchange Capacity (CEC) was above 10 cmolc/kg in Goseonggun and Hadonggun, but below 8.6 cmolc/kg in Jinjusi and Hapcheongtm. Potassium content ranged between 0.07 and 0.14 cmolc/kg, and magnesium was above 0.66 cmolc/kg in all regions. The results indicate that soil property in chestnut stands was different among regions in Gyeongnam province. This suggested that the chestnut stands should be managed by the fertilization application reflected in the variability of regional soil property in chestnut stands.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.9
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• pp.1128-1136
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• 2017

Previous studies of the caffeine consumption pattern were limited primarily to beverages containing caffeine. Therefore, this study examined the caffeine consumption patterns and levels in beverages and foods containing caffeine among high school students (n=310) in the Yongin region. The participants included 171 boys (55.2%) and 139 girls (44.8%). The daily mean caffeine intake of the respondents was 41.27 mg (0.651 mg/kg) and 36.47 mg (0.696 mg/kg) in boys and girls, respectively. Among the caffeinated food groups, coffee had the highest caffeine intake group in both boys (18.95 mg) and girls (26.28 mg). Girls consumed large amounts of caffeine in the form of Americano-style coffee (20.04 mg), whereas boys consumed more canned coffee (6.77 mg) than girls (2.43 mg, P<0.01). Carbonated soft drinks were the second most prevalent source of caffeine intake in both groups, even though boys (14.29 mg) consumed larger amounts of caffeine than girls (5.85 mg, P<0.001). Multiple regression analysis investigating the major contributing food group to daily total caffeine intake also showed that the highest standardized coefficient was in coffee regardless of gender (boys 0.492, P<0.001 and girls 0.944, P<0.001), followed by carbonated soft drinks and energy drinks. Approximately 95% of high school students consumed normal levels of caffeine, whereas 3.5% of boys and 5.8% of girls consumed excessive amounts based on the standard limit of Korea Food and Drug Administration (<2.5 mg/kg/d) for adolescents. The daily mean caffeine intake of the excess group was 5.38 mg/kg and 6.96 mg/kg in boys and girls, respectively. Consequently, safe daily caffeine intake needs to be determined throughout continuous national management guidelines and nutritional education.

• Journal of the Korean Geographical Society
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• v.40 no.4 s.109
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• pp.428-440
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• 2005

There is currently no agreement among archaeologists, environmental historians, and paleoecologists as to the relative significance of pre- and post-Conquest human impact on the environments of Highland Mexico. This paper presents the results of pollen, microscopic charcoal, dung fungal spore, isotope, and magnetic susceptibility analyses on ca. 4m sediment core. The coring site is Hoya Rincon de Parangueo, one of the seven maar lakes in the Valle do Santiago. Amaranthaceae pollen, one of important disturbance indicators and Zea mays pollen obviously indicate two periods of agricultural activities. The first period begins ca. 400 B.C. and ends ca. A.D. 850. The second begins around A.D. 1550 and continues to the present. During the first period, the degree of agricultural activities was related to periodical sunspot cycles and the most intense activities were present between ca. A.D. 150-ca. A.D. 400. The abrupt increase of $\delta^{18}O$ around 280cm may reflect that an important transition to a dry phase took place around A.D. 450. People probably stopped cultivating crops due to dry conditions prevailing since ca. A.D. 450. The second period, the post-Conquest, exhibits a dramatic increase of sporormiella, dung fungal spores resulted fron the introduction of cattle. Low Poaceae frequency and charcoal production and high $\delta^{13}C$ values, magnetic susceptibility, and organic contents all indicate the arrival of the Spanish. Most importantly, it seems that mesquite (Prosopis juliflora) could have benefits from declined fire frequencies caused by cattle grazing. The study area is now entirely dominated by woody plants like mesquite, which clearly demonstrates that serious vegetation change occurred in the study area.

• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.181-187
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• 2017

The purpose of this study was to provide basic data for development of environmental design technology for greenhouses constructed in reclaimed lands. The climatic conditions around seven major reclaimed land areas with a plan to install advanced horticultural complexes in Korea were analyzed. The characteristics of natural ventilation and temperature rise through the thermal environment measurement of the greenhouse in Saemangeum were analyzed. The part to be applied to the environmental design of the greenhouses in reclaimed lands were reviewed. Results of comparing the ventilation rate of the greenhouse according to the presence or absence of plants showed the greenhouse with plants had the lower ventilation rate, but the smaller rise of indoor temperature due to the evapotranspiration of plants. In the greenhouse with plants, the number of air changes was in the range of 0.3 to 0.9 volumes/min and the average was 0.7 volumes/min. The rise of indoor temperature relative to outdoor temperature was in the range of 1 to $5^{\circ}C$ and the average $2.5^{\circ}C$. The natural ventilation performance of the experimental greenhouse constructed in the reclaimed land almost satisfied the recommended ventilation rate in summer and the rise of indoor temperature relative to outdoor temperature did not deviate considerably from the cultivation environment of plants. Therefore, it was determined that the greenhouse cultivation in Saemangeum reclaimed land is possible with only natural ventilation systems without cooling facilities. As the reclaimed land is located in the seaside, the wind is stronger than the inland area, and the fog is frequent. This strong wind speed increases the ventilation rate of greenhouses, which is considered to be a factor for reducing the cooling load. In addition, since the fog duration is remarkably longer than that of inland area, the seasonal cooling load is expected to decrease, which is considered to be advantageous in terms of the operation cost of cooling facilities.