• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.529-533
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• 2017

In this work, a new type of biosorbent was prepared from the biochar of Liriodendron tulipifera L. by adding an activation process using water vapor. By using the biosorbent, the removal characteristics of nikel ions in the water phase were investigated. When the equilibrium experiments to remove both 5 and 10 mg/L of nikel ions were performed, the adsorption amount of nickel ions was 4.2 and 5.4 mg/g, respectively. Also, the optimal initial pH was 6 to increase the removal efficiency with respect to two different nickel concentrations of 5 and 10 mg/L. To enhance the removal efficiency of 10 mg/L of nikel ions, a chemical treatment using critic acid was applied for the biosorbent. In addition, 100% removal efficiency was observed for 10 mg/L of nikel ions when the experiment was conducted for 2 h using the modified biosorbent treated by 4 M of critic acid. The results of desorption experiment to recover nikel ions indicated that 0.1 M of nitrilotriacetic acid (NTA) was selected as the optimal desorption agent. Consequently, these experimental results could be employed as an economical and environmentally friendly technology for the development of nickel removal processes.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1678-1686
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• 2020

This study attempted to derive the possibility of using wood pellet using rice husk, which is an agricultural byproduct, and tried to improve the lower calorific value of rice hulls thorough expansion technology and combustion additives. In the physical and chemical analysis of rice husk, the result was obtained that the chlorine content was 0.09%, which did not meet the wood pellet quality standard of Korea. When making rice hulls into expanded rice husk through the expansion technology, the chlorine content decreased, resulting in a product of 0.02%, which is equivalent to the wood pellet standard of Korea, and the calorific value was also increased to 4,280 kcal/kg compared to the existing 3,780 kcal/kg. To obtain a product of 5,000 kcal/kg or more, borax, hydrogen peroxide, and sodium hydroxide was used as combustion improver. However the improvement in calorific value was insufficient. After conversion to coffee oil path using coffee grounds, which is a waste resource biomass, it is mixed into an expanded rice husk, and when the product is analyzed, the coffee oil 15 wt% mixed product shows an excess of 4,949 kcal/kg. When using rice husk, an agricultural byproduct, as wood pellets, it is considered desirable to use waste resources to improve the calorific value, and according to the results of this study, when mixing coffee oil, rice husk can be sufficiently used as wooden pellets.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.135-141
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• 2012

Purpose: Polymerization of HEMA(2-hydroxyethyl methacrylate) which can be used in the soft contact lens has been performed by using electron beam(EB) irradiation, and examined the best condition for the polymerization. Comparing the physical properties of the contact lenses to the one fabricated by thermal polymerization method, we check the use possibility of the EB irradiation to the fabrication of the soft contact lens. Methods: We investigated the degree of polymerization of the HEMA according to the composition of the monomer, the additive ratio and the dose of electron beam (0~120 kGy). The degree of polymerization was measured depending on the EB dose to research the best synthetic condition under the EB irradiation. The physical properties of the contact lens such as water content(%), oxygen transmissibility(Dk/t) and optical transmittance were analysed by using the FT-IR results with comparing the two different polymerization method (thermal and electron beam polymerization) with same additive ratio. Results: When the dose of electron beam was above 100 kGy, the degree of polymerization of HEMA was above 99% with regardless using cross-linker and initiator. The water content of the lens fabricated by EB method showed 10% higher than the one by the thermal method which was 40%. The lens fabricated by EB method also showed higher oxygen transmissibility(Dk/t) as same with the water content, and showed twice higher value in the lens fabricated by pure HEMA. According to the FT-IR results, hydrophilic property of the lens fabricated by EB method was increased due to increasing the intermolecular hydrogen bonding. It showed above 90% optical transmittance in the visible range of wavelength on the contact lenses fabricated by the both of two different polymerization method. Conclusions: The polymerization of HEMA without cross-linker and initiator was successful above 100 kGy of EB irradiation. Moreover the lens fabricated from the polymer synthesized by pure HEMA with 100 kGy of EB showed the highest water content and oxygen transmissibility. Therefore EB irradiation is another possible method to synthesize the polymer which can be used for the soft contact lens.

• Journal of Applied Biological Chemistry
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• v.60 no.1
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• pp.87-93
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• 2017

The objective of this study was to investigate the physicochemical characteristics and sensory evaluation of dacquoise made with sugar or sugar replacement (tagatose, erythritol). Sugar (S) was replaced with tagatose (T), and sugar powder was replaced with tagatose (TS), and erythritol (TE). S showed the highest sugar contents compared with TS and TE (p <0.05) but there were no significant differences with T. There were not significant differences in specific gravity and spread factor among the sweeteners. S and T tended to have higher loss factors than TS & TE. The more tagatose was increased, the more the redness value increased compared with S, and sucrose showed similar tendency for lightness (redness; TS > T > TE > S, lightness; S > T > TS > TE). TE showed good results for physical characteristics whereas T was better in the sensory test. The above results bear out that tagatose and erythritol both are suitable as alternative sweeteners for making dacquoise, but tagatose was better. Tagatose appeared to be a better replacement for sucrose in baking dacquoise, and dacquoise with 33% of the sugar replaced tagatose (T) could be suitable for use by diabetic and obese people. 95.1% tagatose (TS) maybe appropriate for diabetic patients. In conclusion, tagatose is a suitable sugar replacement for making dacquoise.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.585-591
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• 2018

Characteristics of nano-structured $SiO_2:Zn$ hollow powders prepared in the micro drop fluidized reactor process were investigated with respect to bandgap energy and surface activity. The $SiO_2:Zn$ hollow powders were successfully prepared continuously in the one step process with reasonable production efficiency, with varying the amount of THAM (tris(hydroxymethyl)-aminomethane) additive and concentration of $Zn^{2+}$ ions. The doping of $Zn^{2+}$ ions into $SiO_2$ lattice led to the reduction of bandgap energy by forming the acceptor level of $Zn^{2+}$ below the conduction band of $Si^{4+}$ ions. The hollow shape also contributed to reduce the bandgap energy of $SiO_2:Zn$ powders. The doping of $Zn^{2+}$ ions into $SiO_2$ hollow powders could enhance the surface activity by forming SiO-H stretching and oxygen vacancies at the surface of $SiO_2:Zn$ powders.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.6
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• pp.1656-1664
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• 2015

The effects of lightyellow sophora, Sophora flavescens extract were tested on non-specific immune response and a disease resistance of olive flounder, Paralichthys olivaceus. For feeding trial, weight gain of fish fed different treated groups were not significant differences. Serum analysis of treated and control group did not demonstrated any differences. Lysozyme activity in the kidney and spleen of the 0.05% treated group on $4^{th}$ and $8^{th}$ week showed significant increase, respectively. In addition, phagocytic activity of the 0.05% treated group on $4^{th}$ and 8th week showed significant increase compared to the control group. Histopathology of the liver and kidney tissue of the administrated group for $4^{th}$, $8^{th}$ and $12^{th}$ week showed no particular signs of tissue degeneration. The treated group was higher than control group by analyzing the relative percent survival (RPS) of the experimental challenge of Edwardsiella tarda. Therefore, the lightyellow sophora showed effective in preventing fish-pathogenic edwardsiellosis for a certain period of time.

• Fire Science and Engineering
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• v.28 no.4
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• pp.57-63
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• 2014

This study was performed to test the combustive properties of Medium Density Fibreboard (MDF) specimens treated with piperazinomethyl-bis-phosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), and N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (MDEDAP). MDF Plates were painted in three times with 15 wt% solution of the alkylenediaminoalkyl-bis-phosphonic acids at the room temperature, respectively. After drying specimen treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). It was indicated that the specimens treated with chemicals showed the later time to peak mass loss rate ($TMLR_{peak}$) = (340475) s than that of virgin plate by reducing the burning rate. In adition, the specimens treated with chemicals showed the higher $CO_{mean}$ production (0.0883~0.0963) kg/kg than that of virgin plate. Especially, the specimens treated with chemicals showed the higher mean smoke extinction area ($SEA_{mean}$) ($5m^2/kg{\sim}21.5m^2/kg$) than that of virgin plate. Thus, It is supposed that the combustion-retardation properties were improved by the partial due to the treated alkylenediaminoalkyl-bis-phosphonic acids in the virgin MDF Plate. However, It gave a negative effect on smoke reduction.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.226-231
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• 1998

Hot melt adhesive which is solventless type has been widely used due to the possibility of automated adhesion process. The main purpose of this study is the development of polyamide based hot melt adhesive to improve the property of conventional ethylene-vinyl acetate hot melt adhesive, which has an inherent problem against heat resistance. In this study, it was found that the terpolymers of nylon 6, nylon 66, and nylon 12(CM831, 843P types) instead of nylon homopolymer were suitable base resins for hot melt adhesive, since the disruption of regularity in the polymer chains reduced the crystallinity, resulting in lower melting point and melt viscosity. According to the results, the optimum adhesion property could be obtained by the using 75/25~50/50 weight radio of CM831/843P resin as a base resin. Terpene resin was used as tackifier to improve adhesion and wetting properties. The best result can be obtained with the 10 wt.% addition of terpene resin. The terpene resin acted as proper tackifier in this system which decreased the melt temperature and viscosity, but increased the mechanical strength of adhesive itself. Also, the rheological property of the adhesive changed from typical non-Newtonian behavior to Newtonian behavior as terpene resin was added.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.595-600
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• 2020

The purpose of this paper was to prepare and evaluate solid dispersions (SD) that can increase the dissolution rate of dexibuprofen as a model drug with low solubility in water using saccharides and sugar alcohols as dispersion materials. DSC, XRD, content and content uniformity test, dissolution test, and disintegration test were conducted for physicochemical evaluation of the prepared SD. For the results, it was confirmed using differential scanning calorimetry that fructose, which has a melting point around 120 ℃ of the device operating temperature range, is a suitable excipient for the preparation of SD by the rotary hot-melt granulation (RHMG) method. X-ray diffraction analysis was conducted to confirm that the crystallinity of dexibuprofen was reduced. Disintegration test of the prepared tablet using SD-containing dexibuprofen and fructose confirmed a very fast disintegration time within 1~2 seconds and also showed that the dissolution rate was about 20% faster than that of the dexibuprofen raw material. Dexibuprofen with reduced crystallinity by SD confirmed through the RHMG method can be used to increase the dissolution rate of the drug and increase the disintegration time of the tablet. Thus, it can be used in the manufacturing of various solid preparations.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.259-265
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• 2012

Differently from fly ash, the bottom ash produced from thermal power generation has been treated as an industrial waste matter, and almost reclaimed or was applied with the additive of the part concrete. Bottom ash has various problems to use with the aggregate. Bottom ash is lighter than typically the sand or the gravel and it's physical properties (compressive strength etc.) is somewhat low because of high absorptance. In order to manufacture the ash concrete, we used a bottom ash as a main material and a pure sulfur as a binder. In this study, fundamental research methods that vary the grain-size of bottom ash and the ratio of sulfur vs ash were investigated to improve the quality of ash concrete such as compressive strength. Bottom ash in this research which occurs from domestic 4 place power plants, was checked physical and chemical properties. The compressive strength seems the result which simultaneously undergoes an influence in content of the sulfur and Bottom ash grain-size. We got the result of the maximum 92 MPa. The compressive strength was high result for grain size below 1.2 mm and high sulfur content.