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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. Source


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. Source


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. Source


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. Source


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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