• Nuclear Engineering and Technology
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• v.22 no.2
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• pp.101-107
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• 1990

The PIXE (Proton Induced X-ray Emission) method is applied to the quantitative analysis of trace elements in tap water, red wine, urine and old black powder samples. Sample irradiations are performed with a 1.202 MeV proton beam from the SNU 1.5-MV Tandem Van de Graaff accelerator, and measurements of X-ray spectra are made by the Si(Li) spectrometer To increase the sensitivity of analysis tap water is preconcentrated by evaporation method. As an internal standard, Ni powder is mixed with black powder sample and yttrium solution is added to the other samples. The analyses of the PIXE spectra are carried out by using the AXIL (Analytical X-ray Analysis by Iterative Least-squares) computer code, in which the routine for least-squares method is based on the Marquardt algorithm. The elements such as Mg, Al, Si, Ti, Fe and Zn are analyzed at sub-ppm levels in the tap water sample. In the red wine sample prepared without preconcentration. the element Ti is detected in the amount of 3ppm. In conclusion, the PIXE method is proved to be appropriate for the analysis of liquid samples by relative measurements using the internal standard. and is expected to be improved by the use of evaluated X-ray production cross-sections and the development of sample preparation techniques.

• Korean Journal of Remote Sensing
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• v.36 no.5_1
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• pp.785-791
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• 2020

The radiance measured from satellite has noise due to atmospheric effect. Atmospheric correction is the process of calculating surface reflectance by removing atmospheric effect and surface reflectance is calculated by the Radiative Transfer Model (RTM)-based Look-Up Table (LUT). In general, studies using a LUT make LUT for each channel with the same atmospheric and geometric conditions. However, atmospheric effect of atmospheric factors do not react sensitively in the same channel. In this study, the LUT for each channel of Korea Multi-Purpose SATellite (KOMPSAT)-3/3A was made under the same atmospheric·geometric conditions. And, the accuracy of the LUT was verified by using the simulated Top of Atmosphere radiation and surface reflectance in the RTM. As a result, the relative error of the surface reflectance in the blue channel that sensitive to the aerosol optical depth was 81.14% at the maximum, and 42.67% in the NIR (Near Infrared) channel.

• Journal of the Korean association of regional geographers
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• v.14 no.6
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• pp.736-751
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• 2008

Although a growing number of studies have commonly used a simple areal weighting interpolation method to quantify demographic characteristics of impacted areas in environmental equity analysis, the results obtained are inevitably imprecise because of the method's unrealistic assumption that population is evenly distributed within a census enumeration unit. Two alternative areal interpolation methods such as intelligent areal weighting and regression methods can account for the distributional biases in the estimation of impacted populations by making use of additional information about the geographic distribution of population. This research explores five areal interpolation methods for estimating the population characteristics of impacted areas in environmental equity analysis and evaluates the sensitivity of the outcomes of environmental equity analysis to areal interpolation methods. This study used GIS techniques to allow areal interpolation to be informed by the distribution of land cover types, as inferred from a satellite image. in both the source and target units. Independent samples t-test statistics were measured to verify the environmental equity hypothesis while coefficients of variation were calculated to compare the relative variability and consistency in the socioeconomic characteristics of populations at risk over different areal interpolation methods. Results show that the outcomes of environmental equity analysis in the study area are not sensitive to the areal interpolation methods used in estimating affected populations, but the population estimates within the impacted areas are largely variable as different areal interpolation methods are used. This implies that the use of different areal interpolation methods may to some degree alter the statistical results of environmental equity analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5931-5936
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• 2012

This study was to evaluate the clinical usefulness of the PRESS technique based on the correlation between PRESS technique and biopsy results by applying 3.0T high magnetic field MRS technique for evaluation of non-alcoholic fatty liver disease patients. This experiment were carried out using a 3.0T magnetic resonance imaging equipment. The part data of each spectrum is taken by peak area integration. The part data of resonance peak was used to calculate relative ratio. MR spectral peak in patients with non-alcoholic fatty liver disease is from 0.9 to 1.6 ppm. According to MRS method study result, Patients with NAFLD were obtained with 94% sensitivity and 80% specificity(p=0.000). When compared to normal based on MRS and Biopsy results was valid correlation(r=0.79, p=0.04). Results for NAFLD(r=0.89, p=0.002) also showed a correlation. Therefore, PRESS technique to evaluate patients with non-alcoholic fatty liver disease, the distribution difference between normal liver and fatty liver part is significantly distinguished. Biopsy and MRS fatty liver peak ratio(%) proves high lipid over grade(r = 0.7).

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.1
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• pp.10-20
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• 2010

In recent studies, $PM_{2.5}$ has been reported to be more harmful to human health than $PM_{10}$ because it penetrates more deeply into the lung. We estimated $PM_{2.5}$ related health benefits in Seoul from implementing the World Health Organization (WHO)'s guidelines (annual average $10{\mu}g/m^3$, 24-hour average $25{\mu}g/m^3$) and U.S. Environmental Protection Agency (EPA)'s National Ambient Air Quality Standard (annual average $15{\mu}g/m^3$, 24-hour average $35{\mu}g/m^3$). U.S. EPA's Environmental Benefits Mapping and Analysis Program was utilized for the analysis. It was predicted that the attainment of the WHO annual guideline and U.S. EPA's annual standard, relative to the concentration in 2006, would result in reduction of 2,333~2,895 premature deaths and 1,703~2,121 premature deaths, respectively. If the WHO and EPA's daily standard for $PM_{2.5}$ are attained, 1,211~1,394 and 1,012~1,165 premature deaths could be avoided, respectively. Sensitivity analyses indicated that the estimates were robust regardless of air quality simulation methods for attaining the $PM_{2.5}$ goals. This study provides a quantitative approach to evaluate health risks from air pollution as well as to assess the potential health benefits of improving atmospheric $PM_{2.5}$ concentration. Even considering the intrinsic limitations and uncertainties of the analysis, it is an important information to rationalize the enforcement of $PM_{2.5}$ management policies and measures in Seoul, Korea.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.157-163
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• 2015

To establish National Reference Method (NRM) for $PM_{2.5}$, operational performance of 5 different commercial gravimetric-based $PM_{2.5}$ measuring instruments was assessed at Bulkwang monitoring station from January 23, 2014 to February 28, 2014. First, physical properties, design, and functional performance of the instruments were assessed. Evaluation was carried out to determine whether operating method for the instruments and levels of QA/QC activities meet the data quality objectives (DQOs). To verify whether DQOs were satisfied, reproducibility of QA/QC procedures, accuracy, relative sensitivity, limit of detection, margin of error, and coefficient of determination of the instruments were also evaluated. Results of flow rate measurement of 15 candidate instruments indicated that all the instruments met performance criteria with accuracy deviation of 4.0% and reproducibility of 0.6%. Comparison of final $PM_{2.5}$ mass concentrations showed that the coefficient of determination ($R^2$) values were greater than or equal to 0.9995, and concentration gradient ranged from 0.97 to 1.03. All the instruments satisfied criteria for NRM with the estimated precision of 1.47~2.60%, accuracy of -1.90~3.00%, and absolute accuracy of 1.02~3.12%. This study found that one particular type of measuring instrument was proved to be excellent, with overall evaluation criteria satisfied.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.37-47
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• 1988

The electrochemical behavior of 2-Amino-1-cyclopentene-1-dithiocarboxylate (acdc) was investigated by the use of polarography, cyclic voltammetry and cathodic stripping voltammetry at glassy carbon electrode. In this study, it was found that the dimer of the acdc was deposited on the glassy carbon electrode via one-electron oxidation process at +0.25V vs. SCE. The ring formation between two dithio group occurs along with the elimination of one sulfur atom. The elimination of sulfur atom occurs via two electron oxidation process at +0.8V vs. SCE. The most sensitive cathodic stripping peak due to the formation of the dimer was observed at -0.85V vs. SCE. The peak relationship between current and concentration was fairly linear in the range of 3${\times}10^{-5}{\sim}1.0{\times}10^{-6}$M. The preconcentration procedure enhanced the sensitivity about 100 times for the analysis of acdc using diffusion current. Detection limit was found to be $2.5{\times}10^{-7}$M and relative standard deviation was ${\pm}$4.1 % at $5.0{\times}10^{-6}$M DC polarography.

• Structural Monitoring and Maintenance
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• v.2 no.1
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• pp.77-93
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• 2015

The idea of using measured dynamic characteristics for damage detection is attractive because it allows for a global evaluation of the structural health and condition. However, vibration-based damage detection for complex structures such as long-span cable-supported bridges still remains a challenge. As a suspension or cable-stayed bridge involves in general thousands of structural components, the conventional damage detection methods based on model updating and/or parameter identification might result in ill-conditioning and non-uniqueness in the solution of inverse problems. Alternatively, methods that utilize, to the utmost extent, information from forward problems and avoid direct solution to inverse problems would be more suitable for vibration-based damage detection of long-span cable-supported bridges. The auto-associative neural network (ANN) technique and the probabilistic neural network (PNN) technique, that both eschew inverse problems, have been proposed for identifying and locating damage in suspension and cable-stayed bridges. Without the help of a structural model, ANNs with appropriate configuration can be trained using only the measured modal frequencies from healthy structure under varying environmental conditions, and a new set of modal frequency data acquired from an unknown state of the structure is then fed into the trained ANNs for damage presence identification. With the help of a structural model, PNNs can be configured using the relative changes of modal frequencies before and after damage by assuming damage at different locations, and then the measured modal frequencies from the structure can be presented to locate the damage. However, such formulated ANNs and PNNs may still be incompetent to identify damage occurring at the deck members of a cable-supported bridge because of very low modal sensitivity to the damage. The present study endeavors to enhance the damage identification capability of ANNs and PNNs when being applied for identification of damage incurred at deck members. Effort is first made to construct combined modal parameters which are synthesized from measured modal frequencies and modal shape components to train ANNs for damage alarming. With the purpose of improving identification accuracy, effort is then made to configure PNNs for damage localization by adapting the smoothing parameter in the Bayesian classifier to different values for different pattern classes. The performance of the ANNs with their input being modal frequencies and the combined modal parameters respectively and the PNNs with constant and adaptive smoothing parameters respectively is evaluated through simulation studies of identifying damage inflicted on different deck members of the double-deck suspension Tsing Ma Bridge.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.253-257
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• 2009

To analysis effect of environment factors on productivity of sweet pepper according to greenhouse covering material (glass, plastic film), this was investigated. In glasshouse, outside light was positively correlated with yield as that $100MJ{\cdot}m^{-2}$ of outside light increased $300{\sim}500g{\cdot}m^{-2}$, also cumulative temperature was same tendency. On possibility of model development for yield estimate cumulative temperature was high than outside light. According to covering material, leaf photosynthesis, productivity per out-side light and term in glasshouse was more high 13%, 46%, and 47% compared with plastic film house, respectively. Result of analysis of effect of light, temperature, and $CO_2$ on yield, relative yield coefficient, yield increment coefficient, and yield reduction coefficient in glasshouse were more high 25%, 73%, and 34% compared with plastic film house, respectively. Hence, sweet pepper's growing in glasshouse compare with plastic film house had more productivity, but that had more sensitivity to charge of environment factors.

• Journal of Preventive Medicine and Public Health
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• v.38 no.2
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• pp.203-207
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• 2005

Objectives: Recently, the American Diabetes Association (ADA) redefined the criteria of prediabetes, which has lowered the diagnostic level of fasting plasma glucose (FPG) from 110 to 125 mg/dl, down to levels between 100 to 125mg/dl. The purpose of this study was to determine the predictive cutoff level of FPG as a risk for the development of diabetes mellitus in Korean men. Methods: A retrospective cohort study was conducted on 11,423 (64.5%) out of 17,696 males $\leq$30 years of age, and who met the FPG of $\leq$125 mg/dl and hemoglobin A1c of $\leq$ 6.4% criteria, without a history of diabetes, and who were enrolled at the screening center of a certain university hospital between January and December 1999. The subjects were followed from January 1999 to December 2002 (mean follow-up duration; 2.3(${\pm}0.7$) years). They were classified as normal (FPG <100mg/dl), high glucose (FPG $\geq$100mg/dl and <110mg/dl) and impaired fasting glucose (FPG $\geq$110mg/dl and $\leq$125mg/dl) on the basis of their fasting plasma glucose level measured in 1999. We compared the incidence of diabetes between the 3 groups by performing Cox proportional hazards model and used receiver operating characteristic analyses of the FPG level, in order to estimate the optimal cut-off values as predictors of incident diabetes. Results: At the baseline, most of the study subjects were in age in their 30s to 40s (mean age, 41.8(${\pm}7.1$) year). The incidence of diabetes mellitus in this study was 1.19 per 1,000 person-years (95% CI=0.68-1.79), which was much lower than the results of a community-based study that was 5.01 per 1,000 person-years. The relative risks of incident diabetes in the high glucose and impaired fasting glucose groups, compared with the normal glucose group, were 10.3 (95% CI=2.58-41.2) and 95.2 (95% CI= 29.3-309.1), respectively. After adjustment for age, body mass index, and log triglyceride, a FPG greater than 100mg/dl remained significant predictors of incident diabetes. Using the receiver operating characteristic (ROC) curve, the optimal cutoff level of FPG as a predictor of incident diabetes was 97.5 mg/dl, with a sensitivity and a specificity of 81.0% and 86.0%, respectively. Conclusion: These results suggest that lowering the criteria of impaired fasting glucose is needed in Korean male adults. Future studies on community-based populations, including women, will be required to determine the optimal cutoff level of FPG as a predictor of incident diabetes.