• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.417-423
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• 1976

Corona treatment of PE, PP and PVC showed a dramatic increase of bond strength when lap joints were made between the polymers and aluminum plates. Heating the corona-treated PE and PP, and PVC in a drying oven at 80 and $50^{\circ}C$, respectively, for 15 min reduced the bond strength to about a half of that of corona-treated but unheated polymers, which indicated that the increase of bond strength was not due to oxidation of the polymer surface. The Weibull distribution function was employed to check reliability of the scattered data obtained from testing the lap joints. It is speculated that electron was deposited on the corona-treated polymer surface to enhance bond strength with aluminum.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.373-377
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• 2009

A pathway for the formation of normal $CoAl_2O_4$ particles is suggested. The optimal amount of malonic acid was determined, and the characteristics of the obtained powders were investigated. Normal $CoAl_2O_4$ powders were prepared using solutions of malonic acid and metal nitrates. X-ray diffraction, Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM) measurements, as well as Fourier transform infrared (FTIR) and ultraviolet/visible (UV-Vis) spectroscopy were carried out. Normal $CoAl_2O_4$ crystallites were formed by a solid state reaction between $CoAl_2O_4$ and amorphous aluminum oxide. The optimal molar ratio of malonic acid to the nitrate anions present in the initial solution was found to be 0.30~0.35. The particles were composed of agglomerates of primary particles. The primary particles were 40 nm in size. This size was relatively constant regardless of the preparation temperature. However, the size of the agglomerated particles increased to 220 nm with increasing temperature.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2224-2228
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• 2012

This study describes the ability of capillary electrochromatography (CEC) for the determination of imidacloprid and carbendazim in tomato samples. A novel liquid crystal crown ether modified hybrid silica monolithic column was synthesized, characterized and developed as separation column for the first time. Baseline separation of imidacloprid and carbendazim could be achieved using a mobile phase containing 90% (v/v) 20 mmol/L phosphate buffer (pH 7.0) and 10% (v/v) acetonitrile. The matrix matched calibration curves were linear with correlation coefficient $r^2$ > 0.9998 in the range of 0.20-10.00 mg/L. The limits of detection for imidacloprid and carbendazim were 0.061 and 0.15 mg/kg, respectively, which were below the maximum residue limits established by the European Union as well as Codex Alimentarius. Average recoveries for imidacloprid and carbendazim varied from 101.6-108.0% with relative standard deviations lower than 6.3%. This method was applied to the analysis of tomatoes collected from local markets.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3611-3616
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• 2010

Five new 4- or 8-substituted-7-hydroxycoumarin derivatives (1-5) were synthesized as fluorescent sensors for metal ions. Fluorescent changes and selectivity for metal ions were compared based on the introduction of different ligands and/or testing with different substitution positions of 7-hydroxycoumarin in aqueous solution. Especially, probes 2, 3 and 5 displayed large fluorescence enhancements with $Zn^{2+}$ and $Cd^{2+}$. Probes 2 and 3 showed moderate selectivity for $Zn^{2+}$ over $Cd^{2+}$. On the other hand, probe 4 showed large fluorescence quenching effects upon the addition of $Ag^+$ and $Hg^{2+}$.

• Journal of the Korea Institute of Building Construction
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• v.10 no.6
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• pp.145-154
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• 2010

As buildings have become higher and larger, the use of high performance concrete has increased. With this increase, interest in and use of ultra fine powder admixture is also on the rise. The silica fume and BSF are the admixtures currently being used in Korea. However, silica fume is exclusively import dependent because it is not produced in Korea. In the case of BFS, it greatly improves concrete fluidity and long-term strength. But a problem exists in securing early strength. Furthermore, air-cooled slag is being discarded, buried in landfills, or used as road bed materials because of its low activation energy. Therefore, we investigated in this study the usability of nano-slag (both rapidly-chilled and air-cooled) as an alternative material to the silica fume. We conducted a physic-chemical analysis for the nano-slag powder and performed a mortar test to propose quality standards. The analysis and testing were done to find out the industrial usefulness of the BFS that has been grinded to the nano-level.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.297-312
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• 2014

Food safety is increasingly becoming an important public health issue, as foodborne diseases present a widespread and growing public health problem in both developed and developing countries. The rapid and precise monitoring and detection of foodborne pathogens are some of the most effective ways to control and prevent human foodborne infections. Traditional microbiological detection and identification methods for foodborne pathogens are well known to be time consuming and laborious as they are increasingly being perceived as insufficient to meet the demands of rapid food testing. Recently, various kinds of rapid detection, identification, and monitoring methods have been developed for foodborne pathogens, including nucleic-acid-based methods, immunological methods, and biosensor-based methods, etc. This article reviews the principles, characteristics, and applications of recent rapid detection methods for foodborne pathogens.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.307-310
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• 2008

In the framework of COMS(Communication, Ocean and Meteorological Satellite) programme, the first bipropellant propulsion system for GEO satellite has been developed successfully. So far Korea has its own experience of development of a monopropellant propulsion system for LEO satellites, i.e., KOMPSAT's. Other types of propulsion systems for a satellite, such as cold gas and electric propulsion etc., are being developed somewhere in Korea, however they are not commercialised yet, apart from those two systems aforementioned. This paper mainly focused on the design of the Chemical Propulsion System(CPS) for the COMS, joint scientific and communications satellite. It includes descriptions of the general system design and a summary of the supporting analysis performed to verify suitability for space flight. Essentially it provides an overview and guide to the various engineering rationale generated in support of the COMS CPS design activities. The manufacture and subsequent testing of COMS CPS are briefly discussed. Feasibility of COMS CPS to an interplanetary mission is proposed as well.

• Membrane and Water Treatment
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• v.6 no.4
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• pp.277-292
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• 2015

The extraction of lactic acid by an emulsion liquid membrane (ELM), in batch and continuous mode, has been reported. On the basis of preliminary experiments, the optimum composition of the organic phase (membrane) is determined. When the SPan 80 is used as surfactant, the emulsion breakage exceeds 50%, but only 10% is obtained when the ECA4360 is used. The effects of surfactant, carrier and solute concentrations, phase volume ratio, and stirring speed on the extraction yield were examined and optimized. Surfactant, carrier and diluent used were ECA4360, trilaurylamine (TLA) and dodecane, respectively; 2-ethylhexane-1,3-diol (EHD) is used as a co-surfactant. Under optimal conditions, emulsion breaking is very low and the swelling is kept at its lowest level. Under the pH conditions of fermentation medium, the extraction yield is lower. A mixer-settler continuous system was used for testing these conditions. The residence time, the number of extraction stages and the stability of the emulsion were studied and optimized. The extraction yield obtained exceeds 90%.

• Geomechanics and Engineering
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• v.13 no.3
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• pp.371-384
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• 2017

Physical and mechanical properties of rocks are of interest in many fields, including materials science, petrophysics, geophysics and geotechnical engineering. Uniaxial compressive strength UCS is one of the key mechanical properties, while density and porosity are important physical parameters for the characterization of rocks. The economic interest of carbonate rocks is very important in chemical or biological procedures and in the field of construction. Carbonate rocks exploitation depends on their quality and their physical, chemical and geotechnical characteristics. A fast, economic and reliable technique would be an evolutionary advance in the exploration of carbonate rocks. This paper discusses the ability of ultrasonic wave velocity to evaluate some mechanical and physical parameters within carbonate rocks (collected from different regions within Tunisia). The ultrasonic technique was used to establish empirical correlations allowing the estimation of UCS values, the density and the porosity of carbonate rocks. The results illustrated the behavior of ultrasonic pulse velocity as a function of the applied stress. The main output of the work is the confirmation that ultrasonic velocity can be effectively used as a simple and economical non-destructive method for a preliminary prediction of mechanical behavior and physical properties of rocks.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.148-155
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• 2017

In this study, by using the international standards ISO TS 16774, Part 2 Test method for chemical resistance as a quality control method of injection type repair material used for leakage crack of underground concrete structure, the performance requirement against of chemical environment of underground concrete structures for repair materials was tested. For this testing 3 types for each of the 2 classes of repair materials(synthetic rubber, cement), with a total of 9 types repair materials, were selected and examined. As a result, the test results showed that the smallest performance deterioration by the change in the mass was with the synthetic rubber(RG) type as opposed to the cement type system, showing that the synthetic rubber type had the strongest relative resistance to chemical exposure. Furthermore, it is necessary to investigate the material with high resistance to chemical substances and to examine the material which can increase resistance to sodium hydroxide and sodium chloride in cement system. These results can be used as a basic index for the selection of repair materials with the strongest resistance to chemical environment found in concrete structures. In addition, it is expected that the test results derived in this study can be used as reference data that can be reflected in the quality improvement of the maintenance material to be developed later.