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Chang J.M.,Seoul National University | Won J.-K.,Seoul National University | Lee K.-B.,Seoul National University | Park I.A.,Seoul National University | And 2 more authors.
American Journal of Roentgenology | Year: 2013

Objective. The purpose of this article is to compare the diagnostic performances of shearwave and strain elastography for the differentiation of benign and malignant breast lesions. SUBJECTS AMD METHODS. B-mode ultrasound and shear-wave and strain elastography were performed in 150 breast lesions; 71 were malignant. BI-RADS final assessment, elasticity values in kilopascals, and elasticity scores on a 5-point scale were assessed before biopsy. The results were compared using the area under the receiver operating characteristic curve (AUC). Results. The AUC for shear-wave elastography was similar to that of strain elastography (0.928 vs 0.943). The combined use of B-mode ultrasound and either elastography technique improved diagnostic performance in the differentiation of benign and malignant breast lesions compared with the use of B-mode ultrasound alone (B-mode alone, AUC = 0.851; Bmode plus shear-wave elastography, AUC = 0.964; B-mode plus strain elastography, AUC = 0.965; p > 0.001). With the best cutoff points of 80 kPa on shear-wave elastography and a score between 3 and 4 on strain elastography, the sensitivity was higher in shear-wave elastography, and specificity was higher in strain elastography (95.8% vs 81.7%, p = 0.002; 93.7% vs 84.8%, p = 0.016). In cases of infiltrating ductal carcinoma, mean elasticity scores were lower in grade 3 than in grade 1 and 2 cancers (p = 0.017) with strain elastography causing false-negative findings. Conclusion. The diagnostic performance of shear-wave and strain elastography was similar. Either elastography technique can improve overall diagnostic performance in the differentiation of benign and malignant lesions when combined with B-mode ultrasound. However, the sensitivity and specificity of shear-wave and strain elastography were different according to lesion histologic profile, tumor grade, and breast thickness. © American Roentgen Ray Society.


Son J.-Y.,Yale University | Lee J.-T.,Korea University | Kim K.-H.,Sejong University | Jung K.,Seoul Metropolitan Government Research Institute of Public Health and Environment | Bell M.L.,Yale University
Environmental Health Perspectives | Year: 2012

Background: Numerous studies have linked fine particles [≤ 2.5 μm in aerodynamic diameter (PM2.5)] and health. Most studies focused on the total mass of the particles, although the chemical composition of the particles varies substantially. Which chemical components of fine particles that are the most harmful is not well understood, and research on the chemical composition of PM2.5 and the components that are the most harmful is particularly limited in Asia. Objectives: We characterized PM2.5 chemical composition and estimated the effects of cause-specific mortality of PM2.5 mass and constituents in Seoul, Korea. We compared the chemical composition of particles to those of the eastern and western United States. Methods: We examined temporal variability of PM2.5 mass and its composition using hourly data. We applied an overdispersed Poisson generalized linear model, adjusting for time, day of week, temperature, and relative humidity to investigate the association between risk of mortality and PM2.5 mass and its constituents in Seoul, Korea, for August 2008 through October 2009. Results: PM2.5 and chemical components exhibited temporal patterns by time of day and season. The chemical characteristics of Seoul's PM2.5 were more similar to PM2.5 found in the western United States than in the eastern United States. Seoul's PM2.5 had lower sulfate (SO4) contributions and higher nitrate (NO3) contributions than that of the eastern United States, although overall PM2.5 levels in Seoul were higher than in the United States. An interquartile range (IQR) increase in magnesium (Mg) (0.05 μg/m3) was associated with a 1.4% increase (95% confidence interval: 0.2%, 2.6%) in total mortality on the following day. Several components that were among the largest contributors to PM2.5 total mass-NO3, SO4, and ammonium (NH4)-were moderately associated with same-day cardiovascular mortality at the p < 0.10 level. Other components with smaller mass contributions [Mg and chlorine (Cl)] exhibited moderate associations with respiratory mortality on the following day (p < 0.10). Conclusions: Our findings link PM2.5 constituents with mortality and have implications for policy making on sources of PM2.5 and on the relevance of PM2.5 health studies from other areas to this region.


Park J.-S.,Seoul Metropolitan Government Research Institute of Public Health and Environment | Lee G.-H.,Woosong University
Journal of the Science of Food and Agriculture | Year: 2011

Background: To investigate the volatile compounds and the antibacterial and antioxidant effects of the essential oils of Pinus densiflora needles (EPDN) and Pinus thunbergii needles (EPTN), the volatile compounds of steam-distilled essential oils were analysed by gas chromatography-mass spectrometry. Antibacterial activities were analysed by performing disc-agar diffusion assay and determining the minimum inhibitory concentrations (MICs) of the essential oils. Antioxidant activities were analysed via radical- and nitrite-scavenging activity assays. Results: The yields of EPDN and EPTN were 0.304% (v/w) and 0.296% (v/w), respectively. In the antibacterial activity assay, the MICs of EPDN and EPTN for Klebsiella pneumoniae, Shigella flexneri and Proteus vulgaris were < 0.4 mg mL-1. In the antioxidant activity assay, the 50% inhibitory concentrations (IC50) of EPDN and EPTN were 120 and 30 μg mL-1, respectively. At 1680 μg mL-1, both EPDN and EPTN exhibited > 50% nitrite-scavenging activity. Conclusion: EPDN can be used as a natural antimicrobial substance. Copyright © 2011 Society of Chemical Industry.


Mun S.,Transportation Institute | Lee S.,Seoul Metropolitan Government Research Institute of Public Health and Environment
Cold Regions Science and Technology | Year: 2010

This paper describes how to determine the fatigue-cracking resistance of hot-mix asphalt (HMA) mixtures and formulate a viscoelastic continuum damage algorithm based on the comparison between measured and calculated strain vs. stress histories at low temperatures. The fatigue-cracking resistance characteristics evaluated in this study were based on the dynamic modulus test for material stiffness characterization and the constant-crosshead-rate tension test for fatigue-cracking characterization, using dense-graded and lime-modified HMA mixtures. The main contributions of this paper are the methods for determining the optimum asphalt content of the HMA mixtures to improve fatigue-cracking resistance and for evaluating the fatigue-cracking resistance of various HMA mixtures. © 2010 Elsevier B.V.


Kim K.-H.,Sejong University | Ho D.X.,Sejong University | Jeon J.-S.,Seoul Metropolitan Government Research Institute of Public Health and Environment | Kim J.-C.,Konkuk University
Atmospheric Environment | Year: 2012

The concentrations of PM 10 and PM 2.5 were measured continuously in both indoors and outdoors of the Seoul Metropolitan Subway network, Korea from Oct. 2007 to Apr. 2008. As the platform screen door (PSD) system was installed in the end of 2007 (8-16 Dec. 2007), these PM data were analyzed for the evaluation of its effectiveness on the control of PM levels. The results indicated that the mean PM 10 concentration in the later period (after PSD installation) was significantly reduced by 16% relative to the earlier period. In contrast, in the case of PM 2.5 distinctions were not statistically significant despite a 12% reduction (P<0.05). The overall results of this study suggest that the installation of the PSD and ventilating system should have served as one of the important components for maintaining the air quality in the model subway system. © 2011 Elsevier Ltd.


Lee S.,Seoul Metropolitan Government Research Institute of Public Health and Environment | Mun S.,Seoul National University of Science and Technology | Richard Kim Y.,North Carolina State University
Construction and Building Materials | Year: 2011

This paper describes the effect of lime on composite hot-mix asphalt (HMA) mixtures of aggregate and asphalt binder evaluated using viscoelastic continuum damage analysis, which is based on predicting the effective stress vs. strain equations and microcrack growth. The performance characteristics evaluated in this study included fatigue cracking and rutting resistance in both moisture-damaged and undamaged states. The test methods used in this evaluation were the dynamic modulus test for stiffness characterization, the direct tension test for fatigue cracking characterization, and the triaxial repeated-load permanent deformation test for rutting characterization. The main contribution of this paper is the demonstration of advanced test methods and models that can be used to evaluate the performance of various mixtures with respect to the fatigue damage and rutting performance. © 2011 Elsevier Ltd. All rights reserved.


Nguyen H.T.,Sejong University | Kim M.-Y.,Seoul Metropolitan Government Research Institute of Public Health and Environment | Kim K.-H.,Sejong University
Science of the Total Environment | Year: 2010

The concentrations of total gaseous mercury (TGM) and relevant environmental parameters were measured at a remote area on Jeju Island, Korea from May 2006 to May 2007. The hourly mean concentration of Hg for the entire study period was 3.85 ± 1.68 ng m- 3 (range of 0.10-17.9: n = 7450). The temporal patterns of Hg at the island site were characterized by the relative dominance in spring/fall over summer/winter and in daytime over nighttime. The possible impact of Asian dust (AD) on Hg distribution was examined by assessing its relationship with PM10 data. Because of a strong inverse log-log correlation between Hg and PM10 levels (above 200 μg m- 3), a direct relationship between the two parameters is difficult to account for. However, the analysis of air mass movement patterns confirmed that the Hg levels on Jeju Island were affected most by the combined effects of major source processes in the surrounding areas: industrial and AD (China), industrial (Korea), and volcanic activity (Japan). © 2009 Elsevier B.V. All rights reserved.


Lee S.,Seoul Metropolitan Government Research Institute of Public Health and Environment | Mun S.,Seoul National University of Science and Technology
Expert Systems with Applications | Year: 2014

We report the improvement of a dynamic modulus model using a modified harmony search (MHS) algorithm to describe the resistance to rutting and fatigue cracking of asphalt concrete mixtures. The MHS algorithm was reformulated to improve the harmony search (HS) algorithm by introducing minimum and maximum bandwidths. Using the MHS algorithm, model parameters for lime-modified asphalt concrete mixtures were extracted and a good fit to the dynamic modulus data obtained from laboratory tests was achieved. © 2013 Elsevier Ltd. All rights reserved.


Mun S.,Seoul National University of Science and Technology | Lee S.,Seoul Metropolitan Government Research Institute of Public Health and Environment
Fatigue and Fracture of Engineering Materials and Structures | Year: 2012

This paper describes testing and evaluation of the fatigue resistance potential of hot-mix asphalt mixtures using viscoelastic continuum damage analysis, which is based on dynamic modulus determination, a state-variable approach and damage calculation. The dynamic modulus test for stiffness characterization and the direct tension test for fatigue resistance characterization were used in the testing procedure. The state-variable approach can be used for numerical computation of a viscoelastic convolution integral. A Nelder-Mead simplex search was used in this study to determine the damage parameter of a stiffness reduction function. The fatigue resistance was evaluated as a function of loading rate, asphalt binder content, modifier (e.g. usage of hydrated lime), and temperature, and was found experimentally to have a strong dependence on these factors. © 2011 Blackwell Publishing Ltd.


Patent
Seoul Metropolitan Government Research Institute of Public Health and Environment | Date: 2015-02-25

Disclosed is an apparatus for repelling birds that can be readily installed on a structure and effective in repelling birds. To fundamentally prevent the birds from perching on the structure, the apparatus for repelling birds in accordance with an embodiment of the present invention includes: a fastening means including a first supporting part, a second supporting part and a fastening part interposed between the first supporting part and the second supporting part, and having the first supporting part and the second supporting part protruded in a same direction from either end of the fastening part in such a way that a protruded structure is fitted therein; a stopper being engaged with one of the first supporting part and the second supporting part in such a way that the fastening means is fastened to the structure after the fastening means is fitted on the structure, the stopper being at least one bolt; a supporting means being installed on the fastening means; a wire having at least one end coupled to the supporting means; and a tension adjusting means being installed at a portion where the wire is coupled with the supporting means.

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