• Progress in Medical Physics
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• v.25 no.4
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• pp.255-263
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• 2014

The dosimetry of very small fields is challenging for several reasons including a lack of lateral electronic equilibrium, large dose gradients, and the size of detector in respect to the field size. The objective of this work was to evaluate the suitability of a new commercial synthetic diamond detector, namely, the PTW 60019 microDiamond, for the small field dosimetry in cyberknife photon beams of 6 different collimator size (from 5 mm to 30 mm). Measurements included dose linearity, dose rate dependence, output factors (OF), percentage depth doses (PDD) and off center ratio (OCR). The results were compared to those of pinpoint ionization chamber, diamond detector, microLion liquid Ionization chamber and diode detector. The dose linearity results for the microDiamond detector showed good linearly proportional to dose. The microDiamond detector showed little dose rate dependency throughout the range of 100~600 MU/min, while microLion liquid Ionization chamber showed a significant discrepancy of approximately 5.8%. The OF measured with microDiamond detector agreed within 3.8% with those measured with diode. PDD curves measured with silicon diode and diamond detector agreed well for all the field sizes. In particular, slightly sharper penumbras are obtained by the microDiamond detector, indicating a good spatial resolution. The results obtained confirm that the new PTW 60019 microDiamond detector is suitable candidate for application in small radiation fields dosimetry.

• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.313-322
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• 2018

To investigate the changing patterns of sub-alpine forest vegetation due to climate change requires accumulation of contiguous reference data and continuous monitoring. Furthermore, it is crucial to monitor short-term ecological change of lower level vegetation to understand the trend of long-term vegetation change. Therefore, this study carried out a vegetation survey and tree diameter measurement in 36 plots of Mt. Jiri inhabited by Abies koreana species from 2015 to 2017 to examine the short-term dynamics of Abies koreana seedling and the change of vegetation distribution according to altitude. We analyzed the importance value and MIV (mean importance value) of major species by each stratum as well as the importance value and species diversity index of major species and the change of seedling population by altitude. The results showed that Abies koreana had the highest importance value on tree layer, Rhododendron schlippenbachii on shrub layer and Tripterygium regelii on herb layer. MIV was high in the order of Abies koreana, Rhododendron schlippenbachii and Acer pseudosieboldianum. Regarding the species composition and species diversity index (H') along the altitudinal gradient, Sasa borealis showed high MI and low H' in the elevation less than 1,500 m, and IV of Tripterygium regelii and H' of herb layer were high in the elevation of 1,700 - 1,800 m. Abies koreana seedling decreased by 22.4% from 1,250 n/ha in 2015 to 970 n/ha in 2017 (p <0.05) throughout the investigated area. The decline rate along seedling and sapling height were 22.9% in less than 10 cm, 3.4% in 10-30 cm, 8.9% in 30-50 cm, 39.3% in 50-100 cm, and 55.1% more than 100 cm. Few of A. koreana seedlings appeared due to the dominance of Sasa borealis in the elevation of 1,500 m or less and due to the dominance and high species diversity of Tripterygium regelii in the elevation of 1,700-1,800 m. On the other hand, many of A. koreana seedlings appeared in the elevation of 1,600-1,700 m due to no distribution of S. borealis and T. regelii species in that altitude range. Therefore, we concluded that those seedlings and saplings of A. koreana could be more stable in the altitude of 1,600-1,700 m.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.658-665
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• 2012

A survey of zearalenone contamination was conducted on cereal-based products by using an immunoaffinity column with LC-MS/MS. The calibration curve showed good lineality, with correlation coefficients ($R^2$) of 0.999 in the concentration range from 1 to 250 ng/mL. The limits of detection and quantification were approximately $0.3{\mu}g/kg$ and $1.0{\mu}g/kg$, respectively. The recoveries in the barley tea, Misutgaru and snack ranged from 73.6-107.8%. Zearalenone was detected in 10 samples (11.2% incidence). The highest zearalenone contamination level was $29.7{\mu}g/kg$ in the Misutgaru. This survey was conducted with uncertainty of measurement. The expanded uncertainty for zearalenone was estimated to be $44.9{\pm}5.0{\mu}g/kg$ (k=2, 95% confidence level) and $128.7{\pm}7.9{\mu}g/kg$ (k=2, 95% confidence level) for barley tea, $30.7{\pm}5.8{\mu}g/kg$ (k=2, 95% confidence level) and $173.7{\pm}14.9{\mu}g/kg$ (k=2.26, 95% confidence level) for Misutgaru, and $37.2{\pm}7.4{\mu}g/kg$ (k=2.31, 95% confidence level) and $151.0{\pm}10.4{\mu}g/kg$ (k=2, 95% confidence level) snack at the level of $41.7{\mu}g/kg$ and $166.7{\mu}g/kg$, respectively.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.690-698
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• 1995

The Poly-S $i_{1-x}$G $e_{x}$ thin films were deposited on oxidized Si wafer by RTCVD(rapid thermal chemical vapor deposition) using Si $H_4$and Ge $H_4$, at 450 ~5$50^{\circ}C$. The variation of Ge mole fraction and the deposition rate of S $i_{1-x}$G $e_{x}$ thin film were studied as a function of the deposition temperature and the Ge $H_4$/Si $H_4$input ratio, and the crystal phase and the surface roughness were studied by XRD and AFM(atomic force microscopy), respectively. The experimental results showed that the activation energy for the deposition of poly-S $i_{1-x}$G $e_{x}$ was about 32~37Kca /mol and the deposition rate of S $i_{1-x}$G $e_{x}$ thin films was increased with increasing the deposition temperature and the input ratio. From the analysis of composition, it was known that the Ge mole fraction within the poly-S $i_{1-x}$G $e_{x}$ thin film was decreased with decreasing the input ratio and increasing the deposition temperature. As-deposited S $i_{1-x}$G $e_{x}$ thin films were polycrystalline over the entire experimental range. But those were amorphous at the deposition temperature of 450, 475$^{\circ}C$ and the input ratio of 0.05. By adding the Ge $H_4$, poly-S $i_{1-x}$G $e_{x}$ thin film were deposited at relatively lower deposition temperatures($\leq$ 5$50^{\circ}C$) than those of conventional poly-Si(>$600^{\circ}C$). From surface roughness measurement of poly-S $i_{1-x}$G $e_{x}$ it was found that the surface roughness( $R_{i}$ ) increased with increasing the deposition temperature and input ratio.and input ratio.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.2
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• pp.33-41
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• 2004

Purpose : Film has been the primary tool in coincidence testing between the light field and the radiation field, which constitutes the quality assurance list of a linear accelerator. But there is a great chance of errors being different among the observer when using film. Thus this study set out to use the BIS(Beam Image System) in addition to film in comparing and evaluating coincidence results between the two fields and in searching for the improvement measures. Materials & Methods : Photon beam of 6 and 15MV was exposed to film and the BIS using a linear accelerator. The light and radiation fields were each $50{\times}50,\;100{\times}100,\;and\;200{\times}200mm^2$. The gantry angle was $0^{\circ}$ when using film and $0^{\circ}\;and\;270^{\circ}$ when using the BIS. The devices adopted to test coincidence between the two fields were a ruler and film scanner when using film. With the BIS, the width of the scanned light and radiation fields was measured for errors with setting the X and Y axis. Results : The visual measurements of the observer with film resulted that the radiation field was bigger than the light field and that their maximum error was 1.9mm. The results were the same with the measurements using the film scanner except for the average error, which was less than 1.9mm. On the contrary, the measurements using the BIS showed that the light field was bigger than the radiation field at the gantry angle of $0^{\circ}\;and\;270^{\circ}$. The maximum error was 0.96mm, and the error range was $<{\pm}2mm$ both in the X and Y axis. The average error of ${\Delta}X$, Y was the smallest in the order of the visual film measurements, film scanner measurements, and BIS measurements Conclusion . This requires a careful measurement for accurate quality assurance since errors are much different according to each observer that tests coincidence between visual fields with film. And an observer needs to use another image device or develop a measuring device of his own if it seems necessary for accurate measurements.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.253-258
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• 2006

An empirical model of nitrous oxide emission from agricultural soil has been applied. It is based on the relationship between $N_2O$ and three soil parameters, soil mineral N(ammonium plus nitrate) content in the topsoil(0-15cm), soil water-field pore space, and soil temperature, determined in a study on clay loam and sandy loam at the pepper field in 2004. For comparisons between estimated and observed values of $N_2O$ emissions in the pepper field, it was investigated that $N_2O$ amount in the clay loam and sandy loam were overestimated as 12.2% and less estimated as 30%, respectively. However, $N_2O$ emissions were overestimated as 27.1% in the clay loam and 14.7% in the sandy loam from $N_2O$ gas samples collected once a week at the same time analyzing soil parameters. This modelling approach, based as it is well established and widely used soil measurements, has the potential to provide flux estimates from a much wider range of agricultural sites than would be possible by direct measurement of $N_2O$ emissions.

• Korean Journal of Microbiology
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• v.40 no.1
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• pp.29-36
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• 2004

The purpose of this work was to investigate the relationships between acrylamide degradation by Pseudomonas sp. JK-7 and several relevant physicochemical environment parameters. In initial experiments, the bacterial culture, strain JK-7 isolated from paddy soil sample was developed to grow aerobically with acrylamide as the sole source of carbon and nitrogen. The bacterium was identified as genus Pseudomonas in the basis of use BIOLOG test, and designated as Pseudomunas sp. JK-7. Strain JK-7 could degrade 50 mM acrylamide completely within 72 hours of incubation. Major intermediates resulting from acrylamide degradation were not detected with the HPLC methodology except acrylic acid which appeared to accumulate transiently in the growth medium. The pH increased from 7.0 to 8.7 with complete degradation of the initial 50 mM acrylamide within 72 hours of incubation. pH control in the range of 5 to 9 influenced the growth of JK-7 and acrylamide degradation, whereas it was not examined the growth and degradation at pH 3 or pH 11, respectively. The effect of supplemented carbons (e.g., glucose, fructose, citrate, succinate) on the acrylamide degradation by the test culture of JK-7 was evaluated. The results indicated that the addition of carbons accelerated the bacterial growth and acrylamide degradation compared to those in the absence of supplemented carbons. The effect of supplemented nitrogens on the degradation was monitored. Increasing concentrations of yeast extract resulted in higher growth yield, based on the turbidity measurement, and complete degradation of acrylamide. However, acrylamide degradation was essentially uninfluenced by the addition of $(NH_{4})_{2}SO_{4}$, $NH_4Cl$ or urea. Addition of $AgNO_3$, $CuSO_4$ or $HgCl_2$ except $ZnSO_4$ in the test culture inhibited the degradation of acrylamide and growth of JK-7.

• Journal of Preventive Medicine and Public Health
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• v.28 no.4 s.51
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• pp.863-873
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• 1995

This report describes a preperation and characterization of canine blood lead(Pb) standard reference material(SRM). Three adult beagle dogs(A, B, and C)were orally dosed with gelatin capsules containing $Pb(NO_3)_2$, equivalent to $10\sim80mg$ Pb/kg body weight. Blood was drawn 24 hours after the dose from the cephalic vein into lead free 500ml Pyrex beaker in which EDTA.K was contained as an anticoagulant. The amount of lead given to individual dog was varied arbitrarily. Three month later, 3 canine animals were orally dosed with lead secondarily to make mixed SRM(D1) which was mixed different concentrations of lead in bloods with A1, B1, and C1 in vitro. The SRMs for A, B, C, A1, B1, C1, and D1 were distributed 2ml each into more than 300 lead free bottles, and were stored in refregerator at $4^{\circ}C$. The amount of lead in canine whole blood samples were determined using a Varian 30A atomic absorption spectrophotometer(AAS) with a model GTA-96 graphite tube atomizer with D2 background correction and a Hitachi Z-8100 AAS with Zeeman background correction. The sensitivity and detection limits for lead determination of Varian 30A were $0.46{\mu}g/L,\;0.34{\mu}g/L,\;and\;0.56{\mu}g/L,\;0.14{\mu}g/L$ of Hitachi Z-8100, respectively. Day to day variations in determination of blood lead concentration in a certain sample were $31.11{\pm}1.36{\mu}g/100ml$ by Varian 30A, and $33.08{\pm}0.82{\mu}g/100ml$ by Hitachi Z-8100, showing the difference of 3% between the two results. At the blood lead concentrations of $56.31{\pm}1.98{\mu}g/100ml(A),\;40.89{\pm}0.80{\mu}g/100ml(B),\;59.01{\pm}1.38{\mu}g/100ml(C)$, the precisions of replicated measurements by AAS were 3.52%, 1.96%, and 2.34%, respectively. Coefficient variation(CV) of SRMs(A, B, and C) within a standard sample were ranged from 0.92% to 7.50%, and those between 5 standard samples were 1.21%, 2.64%, and 1.11%, respectively, showing inter-vial variation of $1{\mu}g/100ml$. Lead levels in SRMs during one month storage were unchanged. The overall recoveries were $89.6\sim100.4%,\;91.6\sim101.9%,\;90.3\sim100.0%$ for A, B, and C SRMs, means were $56.46{\pm}2.69{\mu}g/100ml,\;39.35{\pm}1.89{\mu}g/100ml,\;57.40{\pm}2.31{\mu}g/100ml$, and measurement ranges were$52.88{\pm}59.26{\mu}g/100ml,\;37.47{\pm}41.68{\mu}g/100ml,\;54.80{\pm}60.69{\mu}g/100ml$, respectively. Those results were laid within confidence limits values. The lead concentrations in the mixed sample(D1) stored over one month period were ranged from $32.76{\mu}g/100ml\;to\;33.54{\mu}g/100ml$, with CV ranging from 1.2% to 2.7%. The results were similiar to each of single samples(A1, B1, and C1) in respect of homogeneity and stability. Results of the mixed blood sample analysed after 1 month storage at $4^{\circ}C$ by four other laboratories(L1, L2, L3, L4) were similar with those of our laboratory($L5;31.18{\pm}0.24{\mu}g/100ml$, acceptable range by $CDC;25.18\sim37.18{\mu}g/100ml$), showing the concentrations of $25.91{\pm}1.19{\mu}g/100ml(L1),\;34.16{\pm}0.22{\mu}g/100ml(L2),\;35.68{\pm}0.85{\mu}g/100ml(L3),\;30.95{\pm}0.46{\mu}g/100ml(L4)$ in a each samples.

• Journal of Genetic Medicine
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• v.4 no.1
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• pp.45-52
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• 2007

Purpose : A simple, rapid, and highly sensitive analytical method for Gb3 in plasma was developed without labor-ex tensive pre-treatment by electrospray ionization MS/ MS (ESI-MS/MS). Measurement of globotriaosy lceramide (Gb3, ceramide trihex oside) in plasma has clinical importance for monitoring after enzyme replacement therapy in Fabry disease patients. The disease is an X-linked lipid storage disorder that results from a deficiency of the enzyme ${\alpha}$-galactosidase A (${\alpha}$-Gal A). The lack of ${\alpha}$-Gal A causes an intracellular accumulation of glycosphingolipids, mainly Gb3. Methods : Only simple 50-fold dilution of plasma is necessary for the extraction and isolation of Gb3 in plasma. Gb3 in diluted plasma was dissolved in dioxane containing C17:0 Gb3 as an internal standard. After centrifugation it was directly injected and analyzed through guard column by in combination with multiple reaction monitoring mode of ESI-MS/MS. Results : Eight isoforms of Gb3 were completely resolved from plasma matrix. C16:0 Gb3 occupied 50% of total Gb3 as a major component in plasma. Linear relationship for Gb3 isoforms w as found in the range of 0.001-1.0 ${\mu}g$/mL. The limit of detection (S/N=3) was 0.001 ${\mu}g$/mL and limit of quantification was 0.01 ${\mu}g$/mL for C16:0 Gb3 with acceptable precision and accuracy. Correlation coefficient of calibration curves for 8 Gb3 isoforms ranged from 0.9678 to 0.9982. Conclusion : This quantitative method developed could be useful for rapid and sensitive 1st line Fabry disease screening, monitoring and/or diagnostic tool for Fabry disease.

• The Korean Journal of Nuclear Medicine
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• v.36 no.4
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• pp.271-276
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• 2002

Purpose: To measure reliable glomerular filtration rate by using the representative values of transplanted renal depths, which are measured with ultrasonography. Materials and Methods: We included 54 patients (26 men, 28 women), with having both renal scintigraphy and ultrasonography after renal transplantation. We measured GFR with Gates' method using the renal depth measured by ultrasonography, and median and mean ones in each patient. We compared GFR derived from ultrasonography-measured renal depth with GFR derived from median and mean renal depths. The correlation coefficients were obtained among GFR derived from ultrasonography-measured renal depths, median and mean renal depths under linear regression analysis. We determined whether GFR derived from median or mean renal depth could substitute GFR derived from ultrasonography-measured renal depth with Bland-Altman method. We analyze the expected errors of the GFR using representative renal depth in terms of age, sex, weight, height, creatinine value, and body surface. Results: The transplanted renal depths range from 3.20 cm to 5.96 cm. The mean value and standard deviation of renal depths measured by ultrasonography are $4.09{\pm}0.65cm$ in men, and $4.24{\pm}0.78cm$ in women. The median value of renal depths measured by ultrasonography is 4.36 cm in men and 4.14 cm in women. The GFR derived from median renal depth is more consistent with GFR derived from ultrasonography-measured renal depth than GFR derived from mean renal depth. Differences of GFR derived from median and ultrasonography-measured renal depth are not significantly different in the groups classified with creatinine value, age, sex, height, weight and body surface. Conclusion: When median value is adapted as a representative renal depth, we could obtain reliable GFR in transplanted kidney simply.