• Journal of Environmental Science International
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• v.28 no.9
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• pp.785-795
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• 2019

In order to analyze the sensitivity of carbon dioxide flux by soil temperature in the grassplot, carbon dioxide flux and soil temperature were observed 24 times from March, 2010 to March, 2011 at nine sites in the grassplot. The average of $CO_2$ in the grassplot is $2.2{\sim}36.7^{\circ}C$, the highest in August, the lowest in January, and the average of carbon dioxide flux is $12{\sim}1479mgCO_2{\cdot}m^{-2}{\cdot}hr^{-1}$, and the carbon dioxide emission from the grassplot to the atmosphere was 10 times higher in summer than in winter. The temperature response coefficient estimated by the exponential function of carbon dioxide flux according to soil temperature was ranged from 0.1065 to 0.1274, and the increase tendency of $CO_2$ flux with soil temperature was linear at $0{\sim}20^{\circ}C$ and exponential at $20{\sim}40^{\circ}C$. The $Q_{10}$ values for each of nine observation sites on the grassplot was in the range of 2.901 ~ 3.575, and the $Q_{10}$ value using the total data observed in the lawn was estimated to be 3.374. In the homogeneous grassplot area, the average of $Q_{10}$ values by observation point and the $Q_{10}$ value by the total data were estimated similarly.

• Journal of radiological science and technology
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• v.44 no.6
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• pp.655-661
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• 2021

Positron emission tomography (PET) images is affected by acquisition time, short acquisition times results in low gamma counts leading to degradation of image quality by statistical noise. Noise2Void(N2V) is self supervised denoising model that is convolutional neural network (CNN) based deep learning. The purpose of this study is to evaluate denoising performance of N2V for PET image with a short acquisition time. The phantom was scanned as a list mode for 10 min using Biograph mCT40 of PET/CT (Siemens Healthcare, Erlangen, Germany). We compared PET images using NEMA image-quality phantom for standard acquisition time (10 min), short acquisition time (2min) and simulated PET image (S2 min). To evaluate performance of N2V, the peak signal to noise ratio (PSNR), normalized root mean square error (NRMSE), structural similarity index (SSIM) and radio-activity recovery coefficient (RC) were used. The PSNR, NRMSE and SSIM for 2 min and S2 min PET images compared to 10min PET image were 30.983, 33.936, 9.954, 7.609 and 0.916, 0.934 respectively. The RC for spheres with S2 min PET image also met European Association of Nuclear Medicine Research Ltd. (EARL) FDG PET accreditation program. We confirmed generated S2 min PET image from N2V deep learning showed improvement results compared to 2 min PET image and The PET images on visual analysis were also comparable between 10 min and S2 min PET images. In conclusion, noisy PET image by means of short acquisition time using N2V denoising network model can be improved image quality without underestimation of radioactivity.

• Journal of Korean Society on Water Environment
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• v.39 no.4
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• pp.316-328
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• 2023

In this study, the characteristics of nonpoint pollutant outflow and contribution rate of pollution in Songya-stream mainstream and tributaries were analyzed. Further, water pollution management and improvement measures for pollution-oriented rivers were proposed. An on-site investigation was conducted to determine the inflow of major pollutants into the basin, and it was found that pollutants generated from agricultural land and livestock facilities flowed into the river, resulting in a high concentration of turbid water. Based on the analysis results of the pollution load data calculated through actual measurement monitoring (flow and water quality) and the occurrence and emission load data calculated using the national pollution source survey data, the S3 and S6 were selected as the concerned pollution tributaries in the Songya-stream basin. Results of cluster analysis using Pearson correlation coefficient evaluation and Density based spatial clustering of applications with noise (DBSCAN) technique showed that the S3 and S6 were most consistent with the C2 cluster (a cluster of Songya-stream mainstream owned area) corresponding to the mainstream of Songya-stream. The analysis results of the major pollutants in the concerned pollution tributaries showed that livestock and land pollutants were the major pollutants. Consequently, optimal management techniques such as fertilizer management, water gate management in paddy, vegetated filter strip and livestock manure public treatment were proposed to reduce livestock and land pollutants.

• Journal of Yeungnam Medical Science
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• v.16 no.2
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• pp.237-243
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• 1999

We conducted this study to find the optimal correction factor(${\alpha}$) of Lassen's linearization algorithm which has been applied for correction of flow-limited uptake at a high flow range in $^{99m}Tc$ d,l-hexamethylpropy leneamine oxime(HMPAO) and $^{99m}Tc$ ethyl cysteinate dimer(ECD). Ten patients with chronic cerebral infarction were involved in this study. We obtained the corrected $^{99m}Tc$ HMPAO and $^{99m}Tc$-ECD brain SPECT(single photon emission computed tomography) using the algorithm with ${\alpha}$ values that varied from 0.1 to 10 and compared the results with regional cerebral blood flow determined by positron emission tomography (PET-rCBF). The multi-modal volume registration by maximization of mutual information was used for matching between PET-rCBF and SPECT images. The highest correlation coefficient between $^{99m}Tc$-HMPAO and $^{99m}Tc$-ECD brain uptake and PET-rCBF was revealed at ${\alpha}$ 1.4 and 2.1, respectively. We concluded that the ${\alpha}$ values of Lassen's linearization algorithm for $^{99m}Tc$-HMPAO and $^{99m}Tc$-ECD brain SPECT images were 1.4 and 2.1, respectively to indicate cerebral blood flow with comparison of PET-rCBF.

• Journal of Korean Society of Forest Science
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• v.112 no.2
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• pp.127-135
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• 2023

This study aimed to develop biomass allometric equations and estimate carbon emission factors, such as the wood density, biomass-expansion factor, and root-to-shoot ratio, for Platanus occidentalis and Metasequoia glyptostroboides planted in urban areas. Twenty M. glyptostroboides and 25 P. occidentalis trees were harvested, and the dry weights and stem volumes of stems, branches, leaves, and roots (>5 mm) were measured. The wood densities of M. glyptostroboides and P. occidentalis were 0.293 ± 0.008 g cm^-3 and 0.509 ± 0.018 g cm^-3, and the biomass-expansion factors were 1.738 ± 0.031 and 1.561 ± 0.035. The root-to-shoot ratios were 0.446 ± 0.009 and 0.402 ± 0.012. The uncertainty tests (coefficient of variation, %) gave 2.8% and 3.5% values for wood density, 1.8% and 2.3% for biomass-expansion factor, and 2.1% and 2.9% for root-to-shoot ratio, respectively. Among the developed allometric equations, Model I using the diameter at breast height (DBH) was suitable. The allometric equations of M. glyptostroboides and P. occidentalis above ground were y = 1.679 (DBH)^1.315 and y = 0.505 (DBH)^1.896, and the allometric equations of the root and total were y = 0.746 (DBH)^1.315, y = 0.301 (DBH)^1.751, y = 2.422 (DBH)^1.316, and y = 0.787 (DBH)^1.858. If the carbon-emission factors of this study and biomass allometric equations of the three developed models are used to estimate the carbon storage and biomass of urban forests, errors caused by not considering the use of fixed factors and the environmental differences can be reduced.

• The Korean Journal of Nuclear Medicine
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• v.37 no.5
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• pp.288-300
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• 2003

Purpose: To obtain regional blood flow and tissue-blood partition coefficient with time-activity curves from ${H_2}^{15}O$ PET, fitting of some parameters in the Kety model is conventionally accomplished by nonlinear least squares (NLS) analysis. However, NLS requires considerable compuation time then is impractical for pixel-by-pixel analysis to generate parametric images of these parameters. In this study, we investigated several fast parameter estimation methods for the parametric image generation and compared their statistical reliability and computational efficiency. Materials and Methods: These methods included linear least squres (LLS), linear weighted least squares (LWLS), linear generalized least squares (GLS), linear generalized weighted least squares (GWLS), weighted Integration (WI), and model-based clustering method (CAKS). ${H_2}^{15}O$ dynamic brain PET with Poisson noise component was simulated using numerical Zubal brain phantom. Error and bias in the estimation of rCBF and partition coefficient, and computation time in various noise environments was estimated and compared. In audition, parametric images from ${H_2}^{15}O$ dynamic brain PET data peformed on 16 healthy volunteers under various physiological conditions was compared to examine the utility of these methods for real human data. Results: These fast algorithms produced parametric images with similar image qualify and statistical reliability. When CAKS and LLS methods were used combinedly, computation time was significantly reduced and less than 30 seconds for $128{\times}128{\times}46$ images on Pentium III processor. Conclusion: Parametric images of rCBF and partition coefficient with good statistical properties can be generated with short computation time which is acceptable in clinical situation.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2461-2476
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• 2013

To assess environmental contamination with carcinogens, carbonaceous compounds, water-soluble ionic species and trace gaseous species were identified and quantified every three hours for three days st three different atmospheric layer at the heart of chiang-Mai, bangkok and hat-Yai from December 2006 to February 2007. A DRI model 2001 Themal/Optical Carbon Analyzer with the IMPROVE thermal/optical reflectance (TOR) protocol was used to quantify the organic carbon(OC) and elemental carbon content in $PM_{10}$. Diurnal and vertical variability was also carefully investigated. In general, OC and EC contenttration shoeed the highest values at the monitoring period o 21.00-00.00 as consequences of human activities at night bazaar coupled with reduction of mixing layer, decreased wind speed and termination of photolysis nighttime. Morning peaks of carboaceous compounds were observed during the sampling period of 06:00 -09:00, emphasizing the main contribution of traffic emission in the three cities. The estimation of incremental lifetime partculate matter exposure (ILPE) raises concern of high risk of carbonaceous accumulation over workers and residents living close to the observatory sites. The average values of incremental lifrtime particulate matter exposure (ILPE) of total carbon at Baiyoke Suit Hotel and Baiyoke Sky Hotel are approsimately ten time shigher then those air sample collected at prince of songkla University Hat-Yai campus corpse incinerator and fish-can maufacturing factory but only slightly higher than those of rice straw burnig in Songkla province. This indicates a high risk of developing lung cancer and other respiratory diseases across workers and residents living in high buildings located in Pratunam area. Using knowledge of carbonaceous fractions in $PM_{10}$, one can estimate the gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs). Dachs-Eisenreich model highlights the crucial role of adsorption in gas-particle partitioning of low molecular weight PAHs, whereas both absorption and adsorption tend to account for gas-particle partitioning of high molecular weight PAHs in urban residential zones of Thailand. Interestingly, the absorption mode alone plays a minor role in gas-partcle partitiining of PAHs in Chiang-Mai, Bangkok and hat-Yai.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.107-112
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• 2010

The Cu$(In_{1-x}Ga_x)Se_2$ is the absorber material for thin film solar cell with high absorption coefficient of $1{\times}10^5cm^{-1}$. In the case of CIGS, the movable energy band gap from $CuInSe_2$ (1.00 eV) to $CuGaSe_2$ (1.68 eV) can be acquired while controlling Ga contain ratio. Generally, the co-evaporator method have used for development and fabrication of the CIGS absorption layer. However, this method should need many steps and lengthy deposition time with high temperature. For these reasons, in this paper, a new growth method of CIGS layer was attempted to hydride vapor transport (HVT) method. The CIGS mixed-source material reacted for HCl gas in the source zone was deposited on the substrate after transporting to growth zone. c-plane $Al_2O_3$ and undoped GaN were used as substrates for growth. The characteristics of grown samples were measured from SEM and EDS.

• Investigative Magnetic Resonance Imaging
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• v.21 no.3
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• pp.162-170
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• 2017

Purpose: To evaluate the imaging findings of desmoid tumors using various imaging modalities and to evaluate whether diffusion-weighted imaging (DWI) can help differentiate between desmoid and malignant tumors. Materials and Methods: The study included 27 patients with pathologically confirmed desmoid tumors. Two radiologists reviewed 23 computed tomography (CT), 12 magnetic resonance imaging (MRI) and 8 positron emission tomography-computed tomography (PET-CT) scans of desmoid tumors and recorded data regarding the shape, multiplicity, size, location, degree of enhancement, and presence or absence of calcification or hemorrhage. The signal intensity of masses on T1- and T2-weighted imaging and the presence or absence of whirling or band-like low signal intensity on T2-weighted imaging were recorded. The apparent diffusion coefficient (ADC) values of the desmoid tumors in nine patients with DWIs were compared with the ADC values of 32 malignant tumors. The maximum standardized uptake value ($SUV_{max}$) on PET-CT images was measured in 8 patients who underwent a PET-CT. Results: The mean size of the 27 tumors was 6.77 cm (range, 2.5-26 cm) and four tumors exhibited multiplicity. The desmoid tumors were classified by shape as either mass forming (n = 18), infiltrative (n = 4), or combined (n = 5). The location of the tumors was either intra-abdominal (n = 15), within the abdominal wall (n = 8) or extra-abdominal (n = 4). Among the 27 tumors, 21 showed moderate to marked enhancement and 22 showed homogeneous enhancement. Two tumors showed calcifications and one displayed hemorrhage. Eleven of the 12 MR T2-weighted images showed whirling or band-like low signal intensity areas in the mass. The mean ADC value of the desmoid tumors ($1493{\times}10^{-6}mm^2/s$) was significantly higher than the mean of the malignant soft tissue tumors ($873{\times}10^{-6}mm^2/s$, P < 0.001). On the PET-CT images, all tumors exhibited an intermediate $SUV_{max}$ (mean, 3.7; range, 2.3-4.5). Conclusion: Desmoids tumors showed homogenous, moderate to marked enhancement on CT and MRI scans and a characteristic whirling or band-like pattern on T2-weighted images. DWI can be useful for the differentiation of desmoid tumors from malignant soft tissue tumors.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.320-320
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• 2016

Nanocrystalline Carbon thin films have numerous applications in different areas such as mechanical, biotechnology and optoelectronic devices due to attractive properties like high excellent hardness, low friction coefficient, good chemical inertness, low surface roughness, non-toxic and biocompatibility. In this work, we studied the comparison of pure DC power and pulsed DC power in plasma sputtering process of carbon thin films synthesis. Using a close field unbalanced magnetron sputtering system, films were deposited on glass and Si wafer substrates by varying the power density and pulsed DC frequency variations. The plasma characteristics has been studied using the I-V discharge characteristics and optical emission spectroscopy. The films properties were studied using Raman spectroscopy, Hall effect measurement, contact angle measurement. Through the Raman results, ID/IG ratio was found to be increased by increasing either of DC power density and pulsed DC frequency. Film deposition rate, measured by Alpha step measurement, increased with increasing DC power density and decreased with pulsed DC frequency. The electrical resistivity results show that the resistivity increased with increasing DC power density and pulsed DC frequency. The film surface energy was estimated using the calculated values of contact angle of DI water and di-iodo-methane. Our results exhibit a tailoring of surface energies from 52.69 to $55.42mJ/m^2$ by controlling the plasma parameters.