• The Journal of Korean Society for Radiation Therapy
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• v.18 no.2
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• pp.81-87
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• 2006

Purpose: Few researches have been peformed on the dose distribution of the moving organ for radiotherapy so far. In order to simulate the organ motion caused by respiratory function, multipurpose phantom and moving device was used and dosimetric measurements for dose distribution of the moving organs were conducted in this study. The purpose of our study was to evaluate how dose distributions are changed due to respiratory motion. Materials and Methods: A multipurpose phantom and a moving device were developed for the measurement of the dose distribution of the moving organ due to respiratory function. Acryl chosen design of the phantom was considered the most obvious choice for phantom material. For construction of the phantom, we used acryl and cork with density of $1.14g/cm^3,\;0.32g/cm^3$ respectively. Acryl and cork slab in the phantom were used to simulate the normal organ and lung respectively. The moving phantom system was composed of moving device, moving control system, and acryl and cork phantom. Gafchromic film and EDR2 film were used to measure dose ditrbutions. The moving device system may be driven by two directional step motors and able to perform 2 dimensional movements (x, z axis), but only 1 dimensional movement(z axis) was used for this study. Results: Larger penumbra was shown in the cork phantom than in the acryl phantom. The dose profile and isodose curve of Gafchromic EBT film were not uniform since the film has small optical density responding to the dose. As the organ motion was increased, the blurrings in penumbra, flatness, and symmetry were increased. Most of measurements of dose distrbutions, Gafchromic EBT film has poor flatness and symmetry than EDR2 film, but both penumbra distributions were more or less comparable. Conclusion: The Gafchromic EBT film is more useful as it does not need development and more radiation dose could be exposed than EDR2 film without losing film characteristics. But as response of the optical density of Gafchromic EBT film to dose is low, beam profiles have more fluctuation at Gafchromic EBT. If the multipurpose phantom and moving device are used for treatment Q.A, and its corrections are made, treatment quality should be improved for the moving organs.

• Journal of the Korean Electrochemical Society
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• v.4 no.2
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• pp.58-64
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• 2001

YSZ ($8mol\%$ yttria-stabilized zirconia)-modified LSM $(La_{0.85}Sr_{0.15}MnO_3)$ composite cathodes were fabricated by formation of YSZ film on triple phase boundary (TPB) of LSM/YSZ/gas. The YSZ coating film greatly enlarged electrochemical reaction sites from the increase of additional TPB. The composite cathode was formed on thin YSZ electrolyte (about 30 Um thickness) supported on an anode and then I-V characterization and AC impedance analyses were performed at temperature between $700^{\circ}C\;and\;800^{\circ}C$. As results of the impedance analysis on the cell at $800^{\circ}C$ with humidified hydrogen as the fuel and air as the oxidant, R1 around the frequency of 1000 Hz represents the anode Polarization. R2 around the frequency of 100Hz indicates the cathode polarization, and R3 below the frequency of 10 Hz is the resistance of gas phase diffusion through the anode. The cell with the composite cathode produced power density of $0.55\;W/cm^2\;and\;1W/cm^2$ at air and oxygen atmosphere, respectively. The I-V curve could be divided into two parts showing distinctive behavior. At low current density region (part I) the performance decreased steeply and at high current density region (part II) the performance decreased gradually. At the part I the performance decrease was especially resulted from the large cathode polarization, while at the part H the performance decrease related to the electrolyte polarization.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.235-241
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• 2017

This study was carried out to estimate growth characteristics of Kimchi cabbage cultivated in two different growing seasons and three transplanting dates in the greenhouses, and to create a predicting model for the production of Kimchi cabbage based on the growth parameters and climatic elements. Kimchi cabbages were transplanted three times at intervals of two weeks in spring and autumn growing seasons. Sigmoidal models for the estimation of fresh weight (Fw) was designed with days after transplanting, which were Fw=4451.5/[1+exp{-(DAT-34.1)/3.6}]($R^2=0.992$) and Fw=7182.0/[1+exp{-(DAT-53.8)/11.6}] ($R^2=0.979$), respectively. The relationship between fresh weight of Kimchi cabbage and growing degree days (GDD) was highly correlated, and the regression model represented by Fw=4451.5/[1+exp{-(GDD-34.1)/3.6}] ($R^2=0.992$) in spring growing season. The yield of Kimchi cabbage under spring and autumn growing season were estimated 11348.3kg/10a and 15128.2kg/10a, respectively, which were much different than outdoor culture each growing season, while greenhouse cultivation have shown similar results. To estimate the efficacy of prediction yield in Kimchi cabbage, we will need to supplement a predicting model, which was based on the parameters and climatic elements by the field cultivation.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.120-132
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• 2014

Purpose : To compare dynamic susceptibility contrast imaging, diffusion-weighted imaging, and susceptibility-weighted imaging (SWI) for the differentiation of tumor recurrence and delayed radiation therapy (RT)-related changes in patients treated with RT for primary brain tumors. Materials and Methods: We enrolled 24 patients treated with RT for various primary brain tumors, who showed newly appearing enhancing lesions more than one year after completion of RT on follow-up MRI. The enhancing-lesions were confirmed as recurrences (n=14) or RT-changes (n=10). We calculated the mean values of normalized cerebral blood volume (nCBV), apparent diffusion coefficient (ADC), and proportion of dark signal intensity on SWI (proSWI) for the enhancing-lesions. All the values between the two groups were compared using t-test. A multivariable logistic regression model was used to determine the best predictor of differential diagnosis. The cutoff value of the best predictor obtained from receiver-operating characteristic curve analysis was applied to calculate the sensitivity, specificity, and accuracy for the diagnosis. Results: The mean nCBV value was significantly higher in the recurrence group than in the RT-change group (P=.004), and the mean proSWI was significantly lower in the recurrence group (P<.001). However, no significant difference was observed in the mean ADC values between the two groups. A multivariable logistic regression analysis showed that proSWI was the only independent variable for the differentiation; the sensitivity, specificity, and accuracy were 78.6% (11 of 14), 100% (10 of 10), and 87.5% (21 of 24), respectively. Conclusion: The proSWI was the most promising parameter for the differentiation of newly developed enhancing-lesions more than one year after RT completion in brain tumor patients.

• Journal of Trauma and Injury
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• v.20 no.2
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• pp.57-64
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• 2007

Purpose: Clinically, acute respiratory distress syndrome (ARDS) occurs within 72 hours after acute exposure of risk factors. Because of its high fatality rate once ARDS progresses, early detection and management are essential to reduce the mortality rate. Accordingly, studies on early changes of ARDS were started, and serum ferritin, as well the as injury severity score (ISS), which has been addressed in previous studies, thought to be an early predictive indicator for ARDSMethods: From March 2003 to March 2005, we investigated 50 trauma patients who were admitted to the intensive care unit in Dongguk University Medical Center, Gyeongju. The patients were characterized according to age, sex, ISS, onset of ARDS, time onset of ARDS, serum ferritin level (posttraumatic $1^{st}\;&\;2^{nd}$ day), amount of transfused blood, and death. Abdominal computed topography was performed as an early diagnostic tool to evaluate the onset of ARDS according to its diagnostic criteria. The serum ferritin was measured by using a $VIDAS^{(R)}$ Ferritin (bioMeriux, Marcy-1' Etoile, France) kit with an enzyme-linked fluorescent assay method. For statistical analysis, Windows SPSS 13.0 and MedCalc were used to confirm the probability of obtaining a predictive measure from the receiver operating characteristics (ROC) curve. Results: The ISS varied from 14 to 66 (mean: 33.8) whereas the onset of ARDS could be predicted with the score above 30 (sensitivity: 90.0%, specificity: 60.0%, p<0.05). On the posttraumatic $1^{st}$ day, the serum ferritin levels were measured to be from 31 mg/dL to 1,200 mg/dL (mean: 456 mg/dL), and the onset of ARDS could be predicted when the value was over 340 mg/dL (sensitivity: 80.0%, specificity: 65.0%, p<0.05). On the posttraumatic $2^{nd}$ day, the serum ferritin levels were measured to be from 73 mg/dL to 1,200 mg/dL (mean: 404 mg/dL), and the onset of ARDS could be predicted when the value was over 627 mg/dL (sensitivity: 60.0%, specificity: 92.5%, p<0.05). The serum ferritin levels and the ISS were significantly higher on the posttraumatic $1^{st}$ and $2^{nd}$ day in the ARDS group, suggesting that they are suitable indices predicting the onset of ARDS, however relationship between the serum ferritin levels and the ISS was not statistically significant. Conclusion: In this study, we discovered increasing serum ferritin levels in multiple- trauma patients on the posttraumatic $1^{st}$ & $2^{nd}$ day and concluded that both the serum ferritin level and the ISS were good predictors of ARDS. Although they do not show statistically significant relationship to each other, they can be used as independent predictive measures for ARDS. Since ARDS causes high mortality, further studies, including the types of surgery and the methods of anesthesia on a large number of patients are essential to predict the chance of ARDS earlier and to reduce the incidence of death.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.19-32
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• 2007

In Korea, there have been various methods of estimating groundwater recharge which generally can be subdivided into three types: baseflow separation method by means of groundwater recession curve, water budget analysis based on lumped conceptual model in watershed, and water table fluctuation method (WTF) by using the data from groundwater monitoring wells. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, so these methods have various limits to deal with these characteristics. To overcome these limitations, we present a new method of estimating recharge based on water balance components from the SWAT-MODFLOW which is an integrated surface-ground water model. Groundwater levels in the interest area close to the stream have dynamics similar to stream flow, whereas levels further upslope respond to precipitation with a delay. As these behaviours are related to the physical process of recharge, it is needed to account for the time delay in aquifer recharge once the water exits the soil profile to represent these features. In SWAT, a single linear reservoir storage module with an exponential decay weighting function is used to compute the recharge from soil to aquifer on a given day. However, this module has some limitations expressing recharge variation when the delay time is too long and transient recharge trend does not match to the groundwater table time series, the multi-reservoir storage routing module which represents more realistic time delay through vadose zone is newly suggested in this study. In this module, the parameter related to the delay time should be optimized by checking the correlation between simulated recharge and observed groundwater levels. The final step of this procedure is to compare simulated groundwater table with observed one as well as to compare simulated watershed runoff with observed one. This method is applied to Mihocheon watershed in Korea for the purpose of testing the procedure of proper estimation of spatio-temporal groundwater recharge distribution. As the newly suggested method of estimating recharge has the advantages of effectiveness of watershed model as well as the accuracy of WTF method, the estimated daily recharge rate would be an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers and aquifers.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.220-227
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• 2004

Phosphorus desorption study is essential to understanding P behavior in agricultural and environmental soils because phosphorus is considered as two different aspects, a plant nutrient versus an environmental contaminant. This study was conducted to determine soil P buffering power related to P desorption quantity intensity (Q/I) parameters, $Q_{max}$(an index of P release capacity) and $l_0$(an index of the intensity factor), and to investigate the characteristics of relationship between the P desorption Q/I parameters and the soil properties. Soil samples were prepared with treatments of 0 and $100mg\;P\;kg^{-1}$ applied as $KH_2PO_4$ solution. The P desorption Q/I curves were obtained by a procedure using anion exchange resin beads and described by an empirical equation ($Q=aI^{-1}+bln(I+1)+c$). The P desorption Q/I curves for the high available P (${\g}20mg\;kg^{-1}$ of Olsen P) soils were characteristic concave trends with or without soil P enrichment, whereas for the low available P (${\lt}20mg\;kg^{-1}$ of Olsen P) soils, the anticipated Q/I concave curves could not be obtained without a proper amount of P addition. When the soils were enriched in phosphates, the values of desorbed solid phase labile P and solution P, such as $Q_{max}$ and $I_0$ respectively, were increased, but the ratio of $Q_{max}$ versus $I_0$ was decreased. Thus, the slope of desorption Q/I curve represented as phosphorus buffering power, $|BP_0|$, is decreased. The $|BP_0|$ values of the high available P soils ranged between 48 and $61L\;kg^{-1}$ in the P untreated samples and between 18 and $44L\;kg^{-1}$ in the P enriched samples. Overall $|BP_0|$ values of both low and high available P soils treated with $l00mg\;P\;kg^{-1}$ ranged between 14 and $79L\;kg^{-1}$. The $Q_{max}$, values ranged between 71.4 and $173.1mg\;P\;kg^{-1}$, and the lo values ranged between 0.98 and $3.82mg\;P\;L^{-1}$ in the P enriched soils. The $Q_{max}$ and $I_0$ values that control the P buffering power may be not specifically related to a specific soil property, but those values were complicatedly related to soil pH, clay content, soil organic matter content, and lime. Also, phosphorus release activity, however, markedly depended on the desorbability of the applied P as well as the native labile P.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.147-152
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• 2012

This study was conducted to investigate the photosynthetic R. micranthum by natural habitats. In the results, natural habitats didn't affect values of light saturated point, light compensation point and photosynthetic capacity of R. micranthum. We investigated light response curve and chlorophyll content at each habitat. Light compensation points were 11.8 ${\mu}mol\;m^{-2}\;s^{-1}$, 11.5 ${\mu}mol\;m^{-2}\;s^{-1}$ and 10.4 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri, and Mt. Worak. Light saturation points showed that R. micranthum is shade tolerant specie which has the light saturation point approximately 500~600 ${\mu}mol\;m^{-2}\;s^{-1}$. Photosynthetic rates of R. micranthum leaves were 5.5 ${\mu}mol\;m^{-2}\;s^{-1}$, 5.4 ${\mu}mol\;m^{-2}\;s^{-1}$ and 5.6 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri and Mt. Worak. On the other hand, since between $20^{\circ}C$ and $30^{\circ}C$, it appeared that the values of net photosynthetic rates of R. micranthum leaves in all sites were high. Especially, the rates were highest at $25^{\circ}C$. Because of low stomatal transpiration rate in saturation radiance, the moisture utilization efficiency in Yeonha-ri was lower than other habitats. Rates of chlorophyll a, chlorophyll b, and total chlorophyll content in Mt. Worak were no significant difference. Therefore R. micranthum has characteristic of shade tolerant species. The moderate temperature for R. micranthum is between $20^{\circ}C$ and $30^{\circ}C$.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.1-9
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• 2000

Objectives : This study was carried out to investigate the sources of infection and modes of transmission of an outbreak of shigellosis that occurred among pupils of 'M' primary school and residents near the school in Kyongju from Sept. 24 to Oct. 24, 1998. Methods : The subjects who completed a questionnaire and a rectal swab for microbiologic examinations were 1,534 persons (781 males, 753 females), including 469 pupils of 'M' primary school (268 males, 201 females). Bacteriological examinations of underground water and simple piped water were done. Results : The attack rate of diarrhea was 28.7% in the subjects from Sept.24 to Oct. 24, 1958. There was no difference in attack rate of diarrhea by gender, but it was significantly higher in the pupils of 'M' primary school than others (p<0.01). The attack rate of diarrhea by resident areas was no different to the pupils of 'M' primary school, but was significantly higher in the residents of Mohwa 2 Ri except pupils that 'M' primary school is located in (p<0.01). The distribution of date of onset revealed the exposure date to be Sept, 22 and 23 in consideration of incubation periods and common source outbreak followed propagative spread in the epidemic curve. The major characteristics of diarrhea were watery (89.1%) in nature, $1\sim3$ days (72.5%) in duration, $2\sim3$ times (63.9%) in frequency. The clinical symptoms among the diarrheal cases included abdominal pain (74.1%), fever (56.4%), headache (55.9%), chill (40.4%) and tenesmus (31.4%). Conclusions : The source of infection was estimated to be contaminated underground water and simple piped water caused by leakage from the cess pool. It is highly necessary that the management of drinking water and cess fools should be done thoroughly.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.130-140
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• 1989

1) Dormancy brocken weed seeds were planted in soil at 15 days interval from June to December in 1986 and 1987 and test of normality and normal distribution curve were made to determine seasonal distribution characteristics of weed emergence in fields. Monthly emergence distribution pattern of each species can be concluded as following normal distribution equations. E. crusgalli $y={\frac{1}{2.52{\sqrt{2{\pi}}}}}e^{-{\frac{(x-10.057)^2}{12.7}}}$ E. indica $y={\frac{1}{2.17{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.16)^2}{9.45}}}$ A. lividus $y={\frac{1}{7.74{\sqrt{2{\pi}}}}}e^{-{\frac{(x-10.06)^2}{15.46}}}$ S. nigrum $y={\frac{1}{2.7{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.695)^2}{14.58}}}$ C. busrsa-pastoris $y={\frac{1}{2.83{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.02)^2}{16.02}}}$ D. sanguinalis $y={\frac{1}{2.8{\sqrt{2{\pi}}}}}e^{-{\frac{(x-8.58)^2}{15.67}}}$ S. viridis $y={\frac{1}{2.72{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.36)^2}{14.8}}}$ C. album $y={\frac{1}{2.596{\sqrt{2{\pi}}}}}e^{-{\frac{(x-8.07)^2}{13.48}}}$ P. oleraeda $y={\frac{1}{2.45{\sqrt{2{\pi}}}}}e^{-{\frac{(x-10.83)^2}{12.01}}}$ 2) Emergence peak period of weed species tested were from the end of May to early August and yearly variation of emergence was observed in E. crus-galli, S. viridis, S, nigrum, and P. oleracea and this fact may more related to rainfall pattern rather than temperature.