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Seoul, South Korea

Jeon Y.-W.,Korea Testing Laboratory
Environmental Engineering Research | Year: 2015

In this study, we attempted to solubilize protein in slaughter blood (SB) using ultrasonic technology. The application of ultrasonic technology can make enzymatic degradation of SB more effective, which has no comparable alternative for treatment. The SB was homogenized by grinding it for 10 minutes at 10,000 rpm as a pretreatment for preventing its clotting, and then ultrasonic treatment was attempted to solubilize protein in SB. To maximize the efficiency of ultrasonic treatment for SB, the optimum condition of ultrasonic frequency (UF) was determined to be 20 kHz. To optimize the operation conditions of ultrasonification with 20 kHz of frequency, we used response surface methodology (RSM) based on ultrasonic density (UD) and ultrasonification time (UT). The solubilization rate (SR) of protein (%) was calculated to be 101.304 – 19.4205 X1 + 0.0398 X2 + 7.9411 X1 2 + 0.0001 X2 2 + 0.0455 X1X2. From the results of the RSM study, the optimum conditions of UD and UT were determined at 0.5 W/mL and 22 minutes, respectively, and SB treated under these conditions was estimated to have a 95% SR. Also, experimentally, a 95.53% SR was observed under same conditions, accurately reflecting the theoretical prediction of 95%. © 2015 Korean Society of Environmental Engineers. Source

Shin D.,Oak Ridge National Laboratory | Shin H.-G.,Korea Testing Laboratory | Lee H.,Pusan National University
Calphad: Computer Coupling of Phase Diagrams and Thermochemistry | Year: 2014

Thermodynamic modeling of the ZrO2-Gd2O 3-La2O3 system was achieved through the use of the CALPHAD (CALculation of PHAse Diagram) approach to investigate the phase stability of pyrochlore (La1-xGdx)2Zr 2O7, a promising candidate material for thermal barrier coating (TBC) applications. The thermodynamic description of the pyrochlore phase in ZrO2-Gd2O3-La2O3 was extrapolated from the constituent pseudo-binaries and hypothetical end-members of the pyrochlore phase in La2O3-Gd 2O3 were self-consistently derived from the reciprocal relationship. The isothermal sections at 1200 and 1500 C were calculated to elucidate the phase stability of pyrochlore, and the liquidus and solidus in the ternary system were calculated to determine temperature and characteristics of the ternary invariant reactions. Predicted phase stabilities show that pyrochlore dominates the phase stability in the temperature region considered, and its single-phase region shows potential for use in high-temperature thermal barrier coatings. The current thermodynamic study of ZrO2-Gd 2O3-La2O3 can provide guideline to design pyrochlore phase for TBC applications, however, should be considered preliminary because of the lack of experimental information, particularly ternary phase equilibrium data, and awaits future experiments for further validation. © 2013 Elsevier Ltd. Source

Noh T.,Pusan National University | Ryu J.,Pusan National University | Kim J.,Pusan National University | Kim Y.-N.,Korea Testing Laboratory | Lee H.,Pusan National University
Journal of Alloys and Compounds | Year: 2013

Copper-doped lanthanum strontium manganite (LSM) system, La 0.8Sr0.2Mn1-xCuxO 3-δ (0 ≤ x ≤ 0.3), was synthesized using the EDTA-combined citrate process and their characteristics were investigated for solid oxide fuel cell (SOFC) cathode applications. In all compositions, a single perovskite phase was obtained after calcination at 750 °C for 10 h. The maximum electrical conductivity at elevated temperatures was obtained at a composition of x = 0.2 (190 S cm-1 at 750 °C), whereas the sample with x = 0.3 showed the minimum value (100 S cm-1 at 750 °C). The increase in electrical conductivity with increasing Cu contents was attributed to a charge compensating transition of the Mn3+-Mn 4+ and the reason for the decreased value, at x = 0.3, is mainly due to the presence of a second phase. The cathode area specific resistance of the sample with x = 0.2 was 4.3 Ω cm2 at 750 °C, which is lower than that of LSM (x = 0). The enhanced performance with the addition of Cu can be explained by the additional Mn4+ promoting the formation of surface oxygen vacancies when Mn4+ is converted to Mn3+ at high temperatures. Copper ion doping at the B-site of LSM affects the formation of oxygen vacancies, which can enhance the oxygen reduction reaction. © 2013 Elsevier B.V. All rights reserved. Source

Kim K.-M.,Korea Institute of Construction Technology | Heo Y.-S.,Korea Institute of Construction Technology | Kang S.-P.,Woosuk University | Lee J.,Korea Testing Laboratory
Cement and Concrete Composites | Year: 2014

This study proposes using sodium silicate-based nano-silica (SS) in cement composites. The effect of the addition of the proposed nano-silica on cement composites was compared to that of conventional ethyl silicate-based nano-silica (ES) and silica fume (SF). This study found that the inclusion of SS in cement composites has mainly two effects on their properties: one is a fast pozzolanic reaction, and the other is a pore-filling effect in a cement matrix. As a result, SS dramatically improves the early-age strength of cement composites by up to 184% and 152%, compared to a control specimen and the specimen with ES inclusion, respectively. Calorimetry, X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) tests were conducted to monitor the effects of these nano-silicas. © 2013 Elsevier Ltd. All rights reserved. Source

Choi J.,Seoul National University | Park C.G.,Korea Testing Laboratory | Yoona J.,Seoul National University
Transactions of the Royal Society of Tropical Medicine and Hygiene | Year: 2013

Affordable water disinfection is key to reducing the waterborne disease experienced worldwide where resources are limited. A simple electrochemical system that can generate chlorine as a disinfectant from the electrolysis of sodium chloride is an appropriate technology to produce clean water, particularly if driven by solar energy. This study examined the affordability of an electrochemical chlorine generation system using solar energy and developed the necessary design information for its implementationA two-electrode batch reactor, equipped with commercial IrO2-coated electrodes and a solar panel (approximate area 0.2 m2), was used to produce chlorine from a 35g/L solution of NaCl. Results: Within 1 h, sufficient chlorine (0.8 g) was generated to produce clean drinking water for about 80 people for 1 day (target microorganism: Escherichia coli; daily drinking water requirement: 2 L per person; chlorine demand: 4 mg/L; solar power: 650 W/m2 in Seoul, Korea. Small household batteries were demonstrated to be a suitable alternative power source when there is insufficient solar irradiation. Using a 1 m2 solar panel, the reactor would take only 15 min in Seoul, Korea, or 7 min in the tropics (solar power 1300 W/m2), to generate 1 g of chlorine. Conclusion: Thesolar-poweredelectrochemical chlorinegenerationsystemfor whichdesigninformationis providedhere is a simple and affordable way to produce chlorine with which to convert contaminated water into clean drinking water. © Royal Society of Tropical Medicine and Hygiene 2012. All rights reserved. Source

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