Korea Institute of Construction Materials

Gunpo, South Korea

Korea Institute of Construction Materials

Gunpo, South Korea
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Kim S.H.,University of Technology, Sydney | Kim S.H.,Korea Institute of Construction Materials | Shon H.K.,University of Technology, Sydney | Ngo H.H.,University of Technology, Sydney
Journal of Industrial and Engineering Chemistry | Year: 2010

The adsorption characteristics of trimethoprim (TMP) onto powdered activated carbon (PAC) and granular activated carbon (GAC) were studied. The adsorption isotherms could be plotted using the Langmuir, Freundlich and Toth models with a reasonable degree of accuracy. Toth isotherm model was better for describing the adsorption equilibrium than Freundlich model, even though the Langmuir model also agreed with the experimental data well. It shows that the Toth model is adequate for fitting equilibrium data for adsorption of TMP on both PAC and GAC in this study. Fixed-bed breakthrough curves were studied under various operating conditions. The performances of the fixed-bed GAC system was also simulated by a model developed with homogeneous surface diffusion model (HSDM). © 2010 The Korean Society of Industrial and Engineering Chemistry.

Shin H.-C.,Korea Institute of Construction Materials | Miyauchi H.,Chungnam National University | Tanaka K.,Tokyo Institute of Technology
Construction and Building Materials | Year: 2011

The effect of temperature on fatigue resistance in repaired mortar and concrete members through epoxy injection is experimentally studied. First, fatigue equipment capable of inducing a small movement is developed to simulate cracks, which are monitored in a real wall structure. The fatigue test is performed considering three different levels of movement amplitude and four different levels of temperature by using fatigue equipment. From the fatigue test, increases in amplitudes and temperature cause reduced resistance to fatigue. Furthermore, the effect of temperature on the failure mode of epoxy-repaired mortar is evaluated. With higher temperature, the failure mode is changed from mortar failure to mixed failure of epoxy and interface. Then, in the mixed failure mode, resistance to fatigue significantly decreases owing to the temperature effect. © 2010 Elsevier Ltd. All rights reserved.

Gyawali G.,Sun Moon University | Cho S.-H.,Sun Moon University | Woo D.,Korea Institute of Construction Materials | Lee S.W.,Sun Moon University
Korean Journal of Materials Research | Year: 2010

Nano sized SiC particles (270 nm) are easily agglomerated in nickel sulfamate electrolytic bath during a composite electrodeposition process. The agglomeration of nano particles in composite coatings can significantly reduce the mechanical properties of the composite coatings. In this study, Ni-SiC nano composite coatings were fabricated using a conventional electrodeposition process with the aid of ultrasound. Nano particles were found to be distributed homogeneously with reduced agglomeration in the ultrasonicated samples. Substantial improvements in mechanical properties were observed in the composite coatings prepared in presence of ultrasound over those without ultrasound. Ni-SiC composite coatings were prepared with variable ultrasonic frequencies ranging from 24 kHz to 78 kHz and ultrasonic powers up to 300 watts. The ultrasonic frequency of 38 kHz with ultrasonic power of 200 watt was revealed to be the best ultrasonic conditions for homogeneous dispersion of nano SiC particles with improved mechanical properties in the composite coatings. The microstructures, phase compositions, and mechanical properties of the composite coatings were observed and evaluated using SEM, XRD, Vickers microhardness, and wear test. The Vickers microhardness of composite coatings under ultrasonic condition was significantly improved as compared to the coatings without ultrasound. The friction coefficient of the composite coating prepared with an ultrasonic condition was also smaller than the pure nickel coatings. A synergistic combination of superior wear resistance and improved microhardness was found in the Ni-SiC composite coatings prepared with ultrasonic conditions.

Gyawali G.,Sun Moon University | Cho S.-H.,Sun Moon University | Woo D.,Korea Institute of Construction Materials | Lee S.W.,Sun Moon University
Materials Science Forum | Year: 2010

Ni-SiC nano composite coatings were fabricated using electrodeposition technique with the aid of ultrasound. The properties of the nano composite were investigated using SEM and Vicker's microhardness tester. The results demonstrated that the microhardness of composite coatings under ultrasonic vibrations was improved significantly as compared to conventional electrodeposition techniques without ultrasound. The nano particles were found to be distributed homogeneously with reduced agglomeration due to the ultrasonic vibration. © (2010) Trans Tech Publications.

Gyawali G.,Sun Moon University | Cho S.H.,Sun Moon University | Woo D.J.,Korea Institute of Construction Materials | Lee S.W.,Sun Moon University
Transactions of the Institute of Metal Finishing | Year: 2012

Ni-SiC nanocomposite coatings have been prepared by electrodeposition with the application of ultrasound at an ultrasonic frequency of 38 kHz with 200 W ultrasonic power. The observed cavitation effect due to ultrasonic application on surface morphologies, microstructures, mechanical, tribological and corrosion properties of the composite coatings were evaluated by using scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction, Vickers microhardness, and corrosion tests, such as polarisation and electrochemical impedance spectroscopy (EIS) methods. Nanoparticles obtained with homogeneous distribution and reduced agglomeration in samples subjected to ultrasound indicated significant improvements in microhardness and wear resistance of the composite coatings compared to the coatings deposited without ultrasound. Additionally, the corrosion resistance results obtained from polarisation curves and EIS methods in 3?5 wt-%NaCl solution were found to be considerably improved. There appears to be a synergistic end result of improved mechanical properties, and superior wear and corrosion resistance in Ni-SiC composite coatings with the application of ultrasound in these electrodeposits. © 2012 Institute of Metal Finishin.

Jung S.H.,Korea Institute of Construction Materials | Lee M.K.,Jeonju University | Lee S.L.,Mokpo National University | Oh B.H.,Seoul National University
2nd International Conference on Sustainable Construction Materials and Technologies | Year: 2010

In order to achieve sustainability of construction materials, it is necessary to assess the resistance of materials to deteriorating factors. Carbonation is one of the important deteriorating mechanisms which arise in concrete due to environmental conditions. The purpose of this study is to first develop a measurement device for carbon dioxide diffusion coefficients and then to identify the diffusion coefficients of carbon dioxide for various concrete mixtures. To this end, several series of tests have been conducted. The test results indicate that the diffusion coefficient of carbon dioxide increases with an increase of watercement ratio. It is also shown that the diffusion coefficient of carbon dioxide decreases with the increase of relative humidity at the same water-cement ratio. The quantitative values of diffusivity of carbon dioxide for various concretes are presented. The present study may be used to predict realistically the carbonation process in concrete structures under environmental conditions and further to assess the service life of such structures.

News Article | February 15, 2017
Site: www.24-7pressrelease.com

YONGIN-SI, GYEONGGI-DO, SOUTH KOREA, February 14, 2017-- Yun-Gu Cho has been included in Marquis Who's Who. As in all Marquis Who's Who biographical volumes, individuals profiled are selected on the basis of current reference value. Factors such as position, noteworthy accomplishments, visibility, and prominence in a field are all taken into account during the selection process.Dr. Cho has been a general manager and advanced materials team leader for Hyundai Engineering & Construction Co., Ltd. since 1998. Working within the company's research and development division, he has led and contributed to a number of projects in multiple countries over the years. Since 2016, he has been working on concrete mix design for the Hyundai Global Business Center in South Korea, and since 2015, he has been overseeing concrete mix design and durability for the Chacao Channel Bridge in Chile. Dr. Cho has also been handling concrete mix design and durability for the Sheikh Jaber Al-Ahmad Al-Sabah Causeway Bridge in Kuwait since 2012. From 2013 to 2016, he oversaw concrete mix design and durability for the Yavuz Sultan Selim Bridge in Turkey, and from 2010 to 2013, he handled concrete mix design for a nuclear power plant in United Arab Emirates.Dr. Cho's earlier projects with the company involved low carbon, ultra-low heat concrete for mass concrete structures, ultra-high strength fire-resistant and blast-resistant concrete, low heat ultra-strength concrete, standardization for construction safety and eco-friendly construction material, and more. He brings to each project a high level of industry expertise, strong leadership skills, and an exceptional academic foundation.A graduate of Seoul National University, Dr. Cho earned a Bachelor of Arts in civil engineering in 1994, a Master of Engineering in civil engineering in 1996, and a Ph.D. in civil engineering in 2002. His latter studies focused on civil engineering as it relates to concrete. In 2009, Dr. Cho obtained a second Master of Engineering in construction management from Hanyang University. He has utilized his knowledge as a member of the mass concrete committee of the Korea Concrete Institute since 2010, and as a member of the slag committee of the Korean Recycled Construction Resource Institute.In addition to his work with Hyundai and with professional organizations, Dr. Cho has channeled his experience and knowledge to write and publish numerous works for industry publications. He has published several articles in the Journal of the Korea Concrete Institute, including "Control of Thermal Crack in Mass Concrete Using Automated Curing System," published in 2013, and "Experimental Study on Bond Behavior of Retrofit Materials by Bond-Shear Test," published in 2012. Dr. Cho has also published a number of articles in the Journal of the Korean Society of Civil Engineers.Dr. Cho's efforts have been recognized by multiple awards from the chief executive officer of Hyundai Engineering & Construction Co., Ltd. He also received a Commendation Award from the Korea Institute of Construction Materials in 2010. Dr. Cho aims for continued professional excellence and achievements as he moves forward in his career.About Marquis Who's Who :Since 1899, when A. N. Marquis printed the First Edition of Who's Who in America , Marquis Who's Who has chronicled the lives of the most accomplished individuals and innovators from every significant field of endeavor, including politics, business, medicine, law, education, art, religion and entertainment. Today, Who's Who in America remains an essential biographical source for thousands of researchers, journalists, librarians and executive search firms around the world. Marquis now publishes many Who's Who titles, including Who's Who in America , Who's Who in the World , Who's Who in American Law , Who's Who in Medicine and Healthcare , Who's Who in Science and Engineering , and Who's Who in Asia . Marquis publications may be visited at the official Marquis Who's Who website at www.marquiswhoswho.com

Kwon S.-J.,University of California at Irvine | Feng M.Q.,University of California at Irvine | Park S.S.,Korea Institute of Construction Materials
NDT and E International | Year: 2010

Electromagnetic (EM) properties-dielectric constant and conductivity are changed with porosity and saturation in cement-based materials. In this paper, dielectric constant and conductivity are measured in cement mortar with 5 different mixture conditions considering saturation. For the same mixture proportions, durability tests including porosity, chloride diffusion, air permeability, sorptivity, and water diffusion are performed. Among the continuously measured EM properties within 5-20 GHz of frequency range for different saturation, results under 60% of saturation which shows stable results are selected and averaged as one value. The averaged measurements utilizing results under 60% of saturation are compared with those from durability tests. Through the normalization using the results of W/C 40% which shows best durability performances, changing ratios of durability characteristics are evaluated with normalized dielectric constant and conductivity. The behaviors of EM properties with different saturation and their relationships with durability performances are studied.

Varghese J.K.,Ajou University | Na S.J.,Ajou University | Park J.H.,Ajou University | Woo D.,Korea Institute of Construction Materials | And 2 more authors.
Polymer Degradation and Stability | Year: 2010

High molecular-weight poly(propylene carbonate) (PPC) can remain intact upon storage in ambient air or in water for 8 months once the catalyst is completely removed. Catalyst-free pure PPC is also thermally stable below 180 °C. At 200 °C, degradation occurs, mainly due to attack of the chain-ended hydroxyl group onto a carbonate linkage, through which the molecular weight distribution is broadened by simultaneous formation of low and high molecular weight fractions. Incomplete removal of hydrogen peroxide generated during the catalyst preparation results in a prepared polymer that contains a substantial amount of polymer chains grown biaxially from hydrogen peroxide, which gives rise to more severe thermal degradation. Experiments conducted in a weathering chamber at high temperature (63 °C) and high humidity (50%) revealed another degradation process involving chain scission through an attack of water molecules onto the carbonate linkage, which progressively and temporally lowers molecular weight. © 2010 Elsevier Ltd. All rights reserved.

Kim J.Y.,Kangwon National University | Kim S.J.,Korea Institute of Construction Materials | Na J.S.,Kwangwoon University
Applied Chemistry for Engineering | Year: 2010

A new one-shot process was employed to fabricate proton exchange membranes (PEMs) over conventional solvent-casting process. Here, PEMs containing nano-dispersed silica nanoparticles were fabricated using one-shot process similar to the bulk-molding compounds (BMC). Different components such as reactive dispersant, urethane acrylate nonionmer (UAN), styrene, styrene sulfuric acid and silica nano particles were dissolved in a single solvent dimethyl sulfoxide (DMSO) followed by copolymerization within a mold in the presence of radical initiator. We have successfully studied the water-swelling and proton conductivity of obtained nanocomposite membranes which are strongly depended on the surface property of dispersed silica nano particles. In case of dispersion of hydrophilic silica nanoparticles, the nanocomposite membranes exhibited an increase in water-swelling and a decrease in methanol permeability with almost unchanged proton conductivity compared to neat polymeric membrane. The reverse observations were achieved for hydrophobic silica nanoparticles. Hence, hydrophilic and hydrophobic silica nanoparticles were effectively dispersed in hydrophilic and hydrophobic medium respectively. Hydrophobic silica nanoparticles dispersed in hydrophobic domains of PEMs largely suppressed swelling of hydrophilic domains by absorbing water without interrupting proton conduction occurred in hydrophilic membrane. Consequently, proton conductivity and water-swelling could be freely controlled by simply dispersing silica nanopartilces within the membrane.

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