• Journal of Sensor Science and Technology
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• v.32 no.3
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• pp.140-146
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• 2023

Water quality is crucial for human health and the environment. Accurate measurement of the quantity of organic carbon in water is essential for water quality evaluation, identification of water pollution sources, and appropriate implementation of water treatment measures. Total organic carbon (TOC) analysis is an important tool for this purpose. Although other methods, such as chemical oxygen demand (COD) and biochemical oxygen demand (BOD) are also used to measure organic carbon in water, they have limitations that make TOC analysis a more favorable option in certain situations. For example, COD requires the use of toxic chemicals, and BOD is time-consuming and can produce inconsistent and unreliable results. In contrast, TOC analysis is rapid and reliable, providing accurate measurements of organic carbon content in water. However, common methods for TOC analysis can be complex and energy-intensive because of the use of high-temperature heaters for liquid-to-gas phase transitions and the use of acid, which present safety risks. This study focuses on a TOC analysis method using TiO₂ photocatalysis, which has several advantages over conventional TOC analysis methods, including its low cost and easy maintenance. For TiO₂, rutile and anatase powders are mixed with an inorganic binder and spray-coated onto a glass fiber substrate. The TiO₂ powder and inorganic binder solutions are adjusted to optimize the photocatalytic reaction performance. The TiO₂ photocatalysis method is a simple and low-power approach to TOC analysis, making it a promising alternative to commonly used TOC analysis methods. This study aims to contribute to the development of more efficient and cost-effective approaches for water quality analysis and management by exploring the effectiveness and reliability of the developed equipment.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.3
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• pp.457-468
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• 2018

To improve understanding of the physico-chemical characteristics of aerosols in the national park and comparing the air pollution between national park and the urban area nearby national park, the aerosol characterization study was conducted in Bukhansan National Park, Seoul, from July through September 2017. Semi-continuous measurements of $PM_{2.5}$ using PILS (Particle Into Liquid System) coupled with IC (Ion Chromatography) and TOC (Total Organic Carbon) analyzer allowed quantification of concentrations of major ionic species($Cl^-$, $SO_4{^{2-}}$, $NO_3{^-}$, $Na^+$, $NH_4{^+}$, $K^+$, $Mg{^{2+}}$ and $Ca{^{2+}}$) and water soluble organic carbon (WSOC) with 30-minute time resolution. The total mass concentration of $PM_{2.5}$ was measured by T640 (Teledyne) with 5-minute time resolution. The black carbon (BC) and ozone were measured with a minute time resolution. The timeline of aerosol chemical compositions reveals a strong influence from urban area (Seoul) at the site in Bukhansan National Park. Inorganic aerosol composition was observed to be dominated by ammoniated sulfate at most times with ranging from $0.1{\sim}32.6{\mu}g/m^3$ (6.5~76.1% of total mass of $PM_{2.5}$). The concentration of ammonium nitrate, a potential indicator of the presence of local source, ranged from below detection limits to $20{\mu}g/m^3$ and was observed to be highest during times of maximum local urban (Seoul) impact. The total mass of $PM_{2.5}$ in Bukhansan National Park was observed to be 10~23% lower than the total mass of $PM_{2.5}$ in urban area (Gireum-dong and Bulgwang-dong, Seoul). In general, ozone concentration in Bukhansan National Park was observed to be similar or higher than urban sites in Seoul, suggesting additional biogenic VOCs with $NO_x$ from vehicle emission were to be precursors for ozone formation in Bukhansan National Park.

• The Korea Journal of Herbology
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• v.28 no.4
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• pp.25-32
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• 2013

Objectives : The purpose of this study was to evaluate the hepatoprotective effect of Hovenia dulcis extract on acute and chronic liver injuries induced by alcohol and $CCl_4$ in mice and rats. Methods : In acute alcohol-induced liver injury, mice were administered Hovenia dulcis extracts (60 and 200 mg/kg) orally before and after alcohol administration. In chronic alcohol-induced liver injury, mice were administered alcohol containing liquid diet for 4 weeks. The mice were administered H. dulcis extracts (60 and 200 mg/kg) mixed with the liquid diet. In acute $CCl_4$-induced liver injury, rats received a single dose of $CCl_4$ (2 mL/kg in olive oil, intraperitoneally). Rats were administered H. dulcis extracts (30, 100 and 300 mg/kg) before and after $CCl_4$ administrations. After the ends of the administrations, the serum levels of AST and ALT were measured using chemical analyzer, and ${\gamma}$-GTP levels were measured using spectrophotometer. Results : In acute alcohol-induced liver injury, H. dulcis extracts treated group showed significant reduction in ALT levels compared to those of control group. In chronic alcohol-induced liver injury, it inhibited weight-loss compared to normal group and showed significant reduction in AST, ALT and ${\gamma}$-GTP levels compared to control group. In acute $CCl_4$-induced liver injury, it also showed significant reduction in AST, ALT levels compared to control group. Conclusions : The results show that H. dulcis extract has hepatoprotective effect in acute and chronic alcohol-induced liver injury and acute $CCl_4$-induced liver injury. These findings suggest that H. dulcis could be a potent hepatoprotective agent.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.523-528
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• 2023

The applicability as a material to improve solar cell performance was reviewed by synthesizing a phosphor that emits red wavelengths by a liquid synthesis method using a metal salt aqueous solution and a polymer medium as a starting material. An aqueous solution was prepared using nitrate of metals such as Ca, Zn, Al, and Eu, and a precursor impregnated with starch, a natural polymer, was sintered to synthesize CaZnAlO:Eu phosphor powder. The surface structure and composition analysis of the synthesized CaZnAlO:Eu phosphor powder were analyzed by scanning electron microscope(SEM) and energy-dispersed X-ray spectroscopy(EDS). The crystal structure of CaZnAlO:Eu phosphor particles was analyzed by an X-ray diffraction analyzer (XRD). As a result of measuring the photoluminescence(PL) characteristics of the phosphor, it was confirmed that a red phosphor with a light emitting wavelength of 650-780nm was successfully synthesized. According to SEM and EDS analysis, the synthesized Ca₁₄Zn₆Al_9.93O₃₅:Eu³⁺_0.07 phosphor powder has a uniform particle size, and Eu ions used as an activator are present. The synthesized CZA:Eu³⁺ phosphor can be used as a material that can increase the light absorption efficiency of the solar cell by converting ultraviolet or visible light down conversion into a wavelength in the near-infrared region.

• Korean Journal of Environmental Agriculture
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• v.36 no.3
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• pp.175-183
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• 2017

BACKGROUND:The Aromatic rice which is characterized by the flavor of Nurungji when cooked rice, and consumption is increasing recently. The purpose of this study was to investigate the physicochemical characteristics and aroma components of five aromatic rice cultivars according to transplanting time. METHODS AND RESULTS: Quantitative analysis of protein, fat, fatty acid and essential amino acid for five aroma rice cultivars(Hyangmibyeo 2 ho, Aromi, Mihyang, Aranghyangchal, Heughyang)and transplanting time was analyzed by crude protein analyzer, gas chromatography (GC), liquid chromatography (LC) and viscosity analysis was done by using rapid viscosity analyzer (RVA). The content of 2-acetyl-1-pyrroline (2AP) was determined by gas chromatography mass spectrometer. (GC-MS) As a result, the average protein and lipid contents were 6.5% and 2.4%, respectively. The content of essential amino acid showed the highest content at 104.4mg/g. There was no significant change in normal nutrients during the transplanting time. By RVA, cv.Hyangmibyeo 2 ho showed the highest peak and total setback viscosities and lowest breakdown viscosity in early transplantation. The content of 2AP in flavor varieties and transplanting time was quantitatively analyzed by GC-MS. Among the cultivars, Aromi showed the highest 2AP contents at $66.7{\mu}g/100gin$ normal transplanting time. CONCLUSION: cv.Aromi and Hyangmibyeo 2 ho were excellent physicochemical properties and 2AP components contents amongaromatic rice cultivars tested. Theiroptimaltime to transplant was at the beginning of June in the area of Miryang.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.397-401
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• 2016

A new solid oxidizer, pyridinium dinitramide (Py-DN) is a low toxic energetic material which can be utilized as a HPGP (high performance green propellant). In this work, Py-DN was synthesized using various starting materials including potassium sulfamate, pyridine hydrochloride, strong nitric acid and sulfuric acid. Physical and chemical properties of the Py-DN were characterized using UV-Vis, FT-IR and a thermal analyzer and their properties were compared to those of previously prepared salts including ammonium dinitramide[ADN, $NH_4N(NO_2)_2$] and guanidine dinitramide[GDN, $NH_2C(NH_2)NH_2N(NO_2)_2$] in our lab. Endothermic and exothermic decomposition temperatures of Py-DN were $77.4^{\circ}C$ and $144.7^{\circ}C$, respectively. The combustion caloric value was 1739 J/g, which is thermally more sensitive than that of conventional dinitramides. It may enable to lower the decomposition temperature, which can reduce preheating temperature required for satellite thruster applications.

• Journal of Pharmaceutical Investigation
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• v.37 no.3
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• pp.137-148
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• 2007

Using a strain-controlled rheometer [Rheometrics Dynamic Analyzer (RDA II)], the steady shear flow properties of a semi-solid ointment base (vaseline) have been measured over a wide range of shear rates at temperature range of $25{\sim}60^{\circ}C$. In this article, the steady shear flow properties (shear stress, steady shear viscosity and yield stress) were reported from the experimentally obtained data and the effects of shear rate as well as temperature on these properties were discussed in detail. In addition, several inelastic-viscoplastic flow models including a yield stress parameter were employed to make a quantitative evaluation of the steady shear flow behavior, and then the applicability of these models was examined by calculating the various material parameters (yield stress, consistency index and flow behavior index). Main findings obtained from this study can be summarized as follows : (1) At temperature range lower than $40^{\circ}C$, vaseline is regarded as a viscoplastic material having a finite magnitude of yield stress and its flow behavior beyond a yield stress shows a shear-thinning (or pseudo-plastic) feature, indicating a decrease in steady shear viscosity as an increase in shear rate. At this temperature range, the flow curve of vaseline has two inflection points and the first inflection point occurring at relatively lower shear rate corresponds to a static yield stress. The static yield stress of vaseline is decreased with increasing temperature and takes place at a lower shear rate, due to a progressive breakdown of three dimensional network structure. (2) At temperature range higher than $45^{\circ}C$, vaseline becomes a viscous liquid with no yield stress and its flow character exhibits a Newtonian behavior, demonstrating a constant steady shear viscosity regardless of an increase in shear rate. With increasing temperature, vaseline begins to show a Newtonian behavior at a lower shear rate range, indicating that the microcrystalline structure is completely destroyed due to a synergic effect of high temperature and shear deformation. (3) Over a whole range of temperatures tested, the Herschel-Bulkley, Mizrahi-Berk, and Heinz-Casson models are all applicable and have an almostly equivalent ability to quantitatively describe the steady shear flow behavior of vaseline, whereas the Bingham, Casson,and Vocadlo models do not give a good ability.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.68-74
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• 2010

In this study, fluidized-bed pyrolysis has been conducted in order to recover the bitumen contained in the oil sand. Canada Alberta oil sand contains 11.9% of bitumen and the bitumen-derived heavy oil produced in fluidizedbed tends to be upgraded relative to the bitumen. The continuous operation has been performed using $N_2$ as a fluidization gas at 1 atm and $500^{\circ}C$ in a reactor of 170 cm height. The results showed 87.76% of bitumen conversion, where liquid products are 74.45% and gas products are 13.31%. $H_2$, $O_2$, CO, $CO_2$, $CH_4$, and NO and $C_1{\sim}C_4$ hydrocarbons in the gas products were analyzed by on-line gas analyzer and gas chromatography, respectively. The pyrolysis oil was analyzed by using proximate analysis, heavy metal analysis, SIMDIS, asphaltenes, and heating value. By SIMDIS analysis, naphtha was 11.50%, middle distillation was 44.83% and heavy oil was 43.66%. It was obvious that the pyrolysis oil was upgraded compared with bitumens.

• Journal of Korean society of Dental Hygiene
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• v.12 no.3
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• pp.513-520
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• 2012

Objectives : In this study, contact angle and shore D hardness were measured, and a shark fin test was conducted after selecting five addition silicon(Blu-Mousse, BM; EXABITE II, EX; PERFECT, PF; Regisil$^{(R)}$ Rigid, RE; Silagum$^{(R)}$, SI) in order to figure out the properties of elastomeric interocclusal recording materials and reduce errors at interocclusal recording. 8) Methods : A contact angle was measured using a contact angle analyzer. After placing a drop of liquid on the surface of the specimens of interocclusal recording materials, a contact angle was photographed with a CCD camera on the equipment. In terms of a shark fin test, interocclusal recording materials were mixed for the time proposed by the manufacturer and inserted into the split ring of the Shark fin device. Twenty (20) seconds exactly, a metal rod was removed to make the materials slowly absorbed. Once they hardened, fin height was measured with a caliper after separating molds and trimming the specimens. The shore D hardness was measured with a shore D hardness tester(Model HPDSD, Hans Schmidt & Co. Gmbh, Germany) in sixty (60) minutes after fabricating specimens. In each experiment, five specimens, mean and standard deviation were calculated. A one-way ANOVA test was performed at the p>0.05 level of significance. In terms of correlation among the tests, Pearson correlation coefficient was estimated. For multiple comparison, Scheffe's test was carried out. Results : A contact angle was the highest in EX with $99.23^{\circ}$ (p<0.05) while the result of the shark fin test was the longest in RE with 5.45mm. SI was the lowest (0.27mm) with statistical significance. Among the interocclusal recording materials, significant difference was observed in terms of means (p<0.05). The shore D hardness was the highest in SI with 31.0 while RE was significantly low with 16.4 (p<0.05). Among the materials, statistically significant difference was observed in terms of means when compared to the rest materials (RE), BM, RE and SI (PF and EX) and the remaining materials (BM and SI) (p<0.05). In terms of correlations among the tests, a negative correlation occurred between shore D hardness and shark fin test(r=-0.823, p=0.000). Conclusions : According to the study above, it is necessary to understand the properties of interocclusal recording materials and consider contact angle, shark fin test and properties of shore D hardness to select appropriate materials.

• Journal of agricultural medicine and community health
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• v.16 no.2
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• pp.141-153
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• 1991

Free amino acid(FAA), free fatty acid(FFA), and amino acid obtained by hydrolysis of protein components of cystic fluid(CF) of Cysticercus cellulosae in pig and man were analyzed. FFA was analyzed by gas chromatography using Varian model 2700, and flame ionization detector with 6 feet${\times}$1/4inch glass column. Flow rate of $N_2$ was 30 ml/min, $H_2$ was 30 ml/min, air was 350 ml/min respectively and chart speed was 1 cm/min. Amino acid was analyzed by high performance liquid chromatography using Waters model 441, and fluorescence detector at 338nm/425nm with column of amino acid analyzer. Buffer A of mobile phase was pH 3.05 and pH of buffer B was 9.6 respectively. The results obtained were as follows : Seven FFAs containing 12~18 carbons were detected : Saturated fatty acids were lauric acid ($C_{12}$), myristic acid($C_{14}$), palmitic acid($C_{16}$), Stearic acid($C_{18}$). Unsaturated fatty acids were oleic acid($C_{12}^{=1}$), linoleic acid($C_{12}^{=2}$), and one unidentified fatty acid was detected. Generally much more quantity of FFA was determined in CF obtained from pig than that from man. FFA of the largest quantity was palmitic acid; 0.078 mg/ml. Eighteen FAAs were detected and the largest quantity was alanine. Ouantity of alanine was 386 ug/ml in CF from pig 108 ug/ml in CF from man respectively. while histidine in CF from pig was 273 ug/ml, that from man was only 4.3 ug/ml. Eighteen amino acids were identified by hydrolysis of protein in CF from man. But, histidine was not identified in CF from pig. Amino from pig and ug/ml from man.