• Horticultural Science & Technology
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• v.29 no.3
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• pp.201-210
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• 2011

This experiment was conducted to investigate physical and chemical characteristics by volume fractions of root media using peatmoss, perlite, and vermiculite, along with effects on the growth of pot chrysanthemums (Dendranthema ${\times}$ grandiflorum 'Vemini') in a C-channel mat irrigation system. To evaluate the physico-chemical properties of 20 root media, the bulk density, particle density, total pore space, pore space, ash content, organic matter, pH, and electrical conductivity were measured and data were analyzed using principal component analysis (PCA). PCA scores revealed that physico-chemical properties changed by the blending of peatmoss, perlite, and vermiculite. The 20 root media were divided into three main groups by hierarchical cluster analysis. At the end of the experiment, the pH and EC of the root media were measured from media divided into four layers. The pH of root media without plants showed a strong linear relationship and the pH of root media with plants increased exponentially. The change of EC in the root medium was indicated as a hyperbolic curve. Plant growth characteristics according to growth in the 20 root media were analyzed by PCA. It was found that the mixing ratios of the root media affected plant growth characteristics. Therefore, mixing ratio is an important factor for pot-plant production in a subirrigation system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.35-42
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• 2019

Risk assessment and analysis for a medium-to-small sized chemical plant that manufactures a polyester resin by the process of batch-type condensation reaction was conducted using K-PSR technique which is one of the risk assessment methods used to implement the Process Safety Management System (PSM). K-PSR is a risk assessment technique developed by KOSHA to compensate for difficulties caused by the lack of infrastructure of medium-to-small sized chemical plants in the re-evaluation. To apply the K-PSR technique, the entire process of a selected chemical palnt was classified in two review sections, i.e., the condensation reaction process and the dilution/filtration process, and the potential risks of the process about these review sections were identified and classified based on the four guide-words (release, fire.explosion, process trouble, and injury). As the results of the research, refer to recommend of risk rating has been confirmed that non-destructive testing of old facilities and the preparation of LOTO procedures for the electrical equipments are necessary as specific measures to prevent the risk of release and fire.explosion. It was also shown that pressure gauges and thermometers should be installed on the hot-oil supply piping to minimize the process trouble, and exhausting hood should be installed to prevent potential injury.

• Journal of Ginseng Research
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• v.41 no.3
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• pp.379-385
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• 2017

In this study, white ginseng was used as the raw material, which was fermented with Paecilomyces hepiali through solid culture medium, to produce ginsenosides with modified chemical composition. The characteristic chemical markers of the products thus produced were investigated using rapid resolution liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (RRLC-QTOF-MS). Chemical profiling data were obtained, which were then subjected to multivariate statistical analysis for the systematic comparison of active ingredients in white ginseng and fermented ginseng to understand the beneficial properties of ginsenoside metabolites. In addition, the effects of these components on biological activity were investigated to understand the improvements in the phagocytic function of macrophages in zebrafish. According to the established RRLC-QTOF-MS chemical profiling, the contents in ginsenosides of high molecular weight, especially malonylated protopanaxadiol ginsenosides, were slightly reduced due to the fermentation, which were hydrolyzed into rare and minor ginsenosides. Moreover, the facilitation of macrophage phagocytic function in zebrafish following treatment with different ginseng extracts confirmed that the fermented ginseng is superior to white ginseng. Our results prove that there is a profound change in chemical constituents of ginsenosides during the fermentation process, which has a significant effect on the biological activity of these compounds.

• Membrane and Water Treatment
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• v.9 no.6
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• pp.447-454
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• 2018

Although flotation techniques are often used for the removal of algal particles, the practicality of algae-harvesting technologies is limited owing to the complex and expensive facilities and equipment required for chemical coagulation. Here, we examined the feasibility of an approach to separating algal particles from water bodies without the need for chemical coagulants, depending on the condition of the algae, and to determine the optimal conditions. Using Anabaena sp., a cyanobacterium causes algal blooms in lakes, we stimulated auto-flocculation in algal particles without coagulants and conducted solid-liquid separation experiments of algal particles under various conditions. The six cultivation columns included in our analysis comprised four factors: Water temperature, light intensity, nutrients, and carbon source; auto-flocculation was induced under all treatments, with the exception of the treatment involving no limits to all factors, and algal particles were well-settled under all conditions for which auto-flocculation occurred. Meanwhile, flotation removal of auto-flocculated algal particles was attained only when nutrients were blocked after algae were grown in an optimal medium. However, no significant differences were detected between the functional groups of the extracellular polymeric substances (EPSs) of floated and settled algal particles in the FT-IR peak, which can cause attachment by collision with micro-bubbles.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.1
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• pp.91-95
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• 1999

The Streptomyces albulus broth, when the polylysine in the broth, that has powerful growth inhibiting effect far many microbes, is its maximum, had filtered off the cells, to use the broth as preservative for keeping favorable taste of Korean Kimchi. Some microorganisms in their specific growth medium, known to deteriorate the useful nutrient of the Kimchi, has grown with different amounts of the inhibiting broth, to determine the minimum growth inhibition concentration. The ${\varepsilon}$-poly-L-lysine had been identified from the IR spectroscopic analysis of the purified poly lysine of the broth from ion exchange chromatographic separation. The content of the polylysine had been determined by methyl orange decoloration effect. Though the minimum inhibition concentration, evaluated by the naked eye based on the conventional method measuring the turbid feature after 18 hours of culture, has different values each other, the observed effects confirmed that the crude broth could be used as a natural preservative for the Kimchi in extending the fair taste.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.42.3-42.3
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• 2017

We present the analysis of chemical abundances and kinematics for six hypervelocity star (HVS) candidates. These objects are G/K-type low-mass stars in the Galactic disk, while other HVSs previously found are B-type high-mass objects in the Galactic halo. The stellar orbits and kinematics of our HVS candidates suggest that they do not originate in the Galactic center or in an accretion event, indicative of yet-unknown mechanisms that produce kinematically-extreme disk stars. In order to study in detail their origin, we obtained medium-resolution (R~6000) spectra of these stars and derived abundances of several chemical elements (Mg, Ca, Si, Ti, Cr, Fe, and Ni). From the comparison of the chemical abundances with the Galactic stellar components (disk, bulge, halo, and dwarf galaxies) and the kinematic properties of our HVSs, we conclude that two of them are likely ejected from the Galactic disk, one originated from the Galactic center as for the young B-type HVSs, and the other one might be ejected from either the Galactic disk or other regions.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.3
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• pp.138-145
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• 2012

An ${\alpha}$-Ferrite (Fe) powder dispersed with 4 vol.% of $Al_2O_3$ was successfully produced by a simple miling at 210 K with a mixture of $Fe_2O_3$, Fe and Al ingredient powders, followed by 2 step high temperature consolidation: Hot Pressing (HP) at 1323 K and then Hot Isostatic Pressing at 1423 K. The microstructure of the consolidated material was characterized by standard metallographic techniques such as XRD (X-ray Diffraction), TEM and STEM-EDS. The results of STEM-EDS analysis showed that the HIPed materials comprised a mixture of pure Fe matrix with a grain size of ~20 nm and $Al_2O_3$ with a bimodal size distribution of extremely fine (~5 nm) and medium size dispersoids (~20 nm). The mechanical properties of the consolidated materials were characterized by compressive test and micro Vickers hardness test at room temperature. The results showed that the yield strength of the ODS (Oxide Dispersion Strengthened) Fe alloy are as much as $674{\pm}39$ MPa and the improvement of the yield strength is attributed to the presence of the fine $Al_2O_3$ dispersoid.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.203-208
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• 1998

A simple on-line measurement system consisting of a conventional peristaltic pump, a HPLC-type heater, and a flow-through spectrophotometer is introduced for the determination of chemical oxygen demand(CODI. The system was configured such that the reaction mixture in the highly concentrated surffuric acrid medium flowing through the PTFE reaction tubing was heated at 150℃ and the absorbance of dichromate was continuously moutored at 445 m. The same addation principle as in the standard procedure was employed akcept the use of CoSO4 as a new effective catalyst. To test the system, potassium hydrogen phthalate was selected as a COD standard material. With suitably optimized reaction condition, the applicable concentration range depends on the concentration of potassium dichromate in the oxidizing reagent. With 2.0×10-3 M and 5.0×10-4M dichromate, the linear dynamic range was observed up to 400 ppm and 100 ppm, respectively. The standards in the Unear ranges were shown to be completely oxidized, which was confirmed with sodium oxalate or Mohr's salt. In all cases, the typical reproduclbility for betweenruns was 2% or less. The proposed measurement system provides the valuable in- formation for the further development of automated analysis system based on the present standard procedure.

• Composites Research
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• v.32 no.1
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• pp.56-64
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• 2019

In this paper, a model is developed to simulate carbon/carbon composite fabrication using chemical vapor infiltration, considering density and porosity change in the preform and multi-step hydrocarbons reactions. The model considers the preform as a porous medium whose diffusion and flow properties changes due to the porosity. To verify the theoretical model, two numerical analyses were performed for the case that the flow inside the preform is zero and the case that the flow inside the preform is calculated by fluid mechanics. The numerical results showed good agreement with the experimental data.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2724-2730
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• 2012

A new heterogeneous acidic catalyst was successfully prepared by impregnation of silica (Aerosil 300) by an acidic ionic liquid, named 1-(4-sulfonic acid)butylpyridinium hydrogen sulfate [$PYC_4SO_3H$][$HSO_4$], and characterized using FT-IR spectroscopy, the $N_2$ adsorption/desorption analysis (BET), thermal analysis (TG/DTG), and X-ray diffraction (XRD) techniques. The amount of loaded acidic ionic liquid on Aerosil 300 support was determined by acid-base titration. This new solid acidic supported heterogeneous catalyst exhibits excellent activity in the synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-ones by cyclocondensation reaction of 2-aminobenzamide with aromatic aldehydes under solvent-free conditions and the desired products were obtained in very short reaction times with high yields. This catalyst has the advantages of an easy catalyst separation from the reaction medium and lower problems of corrosion. Recycling of the catalyst and avoidance of using harmful organic solvent are other advantages of this simple procedure.