• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.24-27
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• 2009

Solid-state dye-sensitized solar cells (DSSCs) have been constructed employing supramolecular electrolytes with multiple hydrogen bonding. A supramolecule was facilely synthesized by one-pot reaction between the amines of methyl isocytosine (MIC) and the epoxy groups of poly(ethylene glycol diglycidyl ether) (PEGDGE) to produce quadruple hydrogen bonding units. Hydrogen bonding interactions and dissolution behavior of salt in supramolecular electrolytes are investigated. The ionic conductivity of the supramolecular electrolytes with ionic liquid, i.e. 1-methyl-3-propylimidazolium iodide (MPII) reaches $8.5{\times}10^{-5}$ S/cm at room temperature, which is higher than that with metal salt (KI). A worm-like morphology is observed in the FE-SEM micrographs of $TiO_2$ nanoporous layer, due to the connection of $TiO_2$ nanoparticles resulting from adequate coating by electrolytes. DSSCs employing the supramolecular electrolytes with MPII and KI exhibit an energy conversion efficiency of 2.5 % and 0.5 %, respectively, at 100 $mW/cm^2$, indicating the importance of the cation of salt. Solar cell performances were further improved up to 3.7 % upon introduction of poly(ethylene glycol dimethyl ether) (PEGDME) with 500 g/mol.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.216-225
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• 2020

An esterase gene, estA1, was cloned from Alteromonas sp. 39-G1 isolated from the Beaufort Sea. The gene is composed of 1,140 nucleotides and codes for a 41,190 Da protein containing 379 amino acids. As a result of a BLAST search, the protein sequence of esterase EstA1 was found to be identical to Alteromonas sp. esterase (GenBank: PHS53692). As far as we know, no research on this enzyme has yet been conducted. Phylogenetic analysis showed that esterase EstA1 was a member of the bacterial lipolytic enzyme family IV (hormone sensitive lipases). Two deletion mutants (Δ20 and Δ54) of the esterase EstA1 were produced in Escherichia coli BL21 (DE3) cells with part of the N-terminal of the protein removed and His-tag attached to the C-terminal. These enzymes exhibited the highest activity toward p-nitrophenyl (pNP) acetate (C₂) and had little or no activity towards pNP-esters with acyl chains longer than C₆. Their optimum temperature and pH of the catalytic activity were 45℃ and pH 8.0, respectively. As the NaCl concentration increased, their enzyme activities continued to increase and the highest enzyme activities were measured in 5 M NaCl. These enzymes were found to be stable for up to 8 h in the concentration of 3-5 M NaCl. Moreover, they have been found to be stable for various metal ions, detergents and organic solvents. These salt-tolerant and chemical-resistant properties suggest that the enzyme esterase EstA1 is both academically and industrially useful.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.32-44
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• 1983

In case of $K_{Imax}$ < $K_{Iscc}$, the corrosion fatigue of high strength steel in 0.1N $H_{2}$S $O_{4}$ solution and 3.5% salt water is as follows. 1. The fatigue life shortens in order of 3.5% salt water and 0.1N $H_{2}$S $o_{4}$ solution. 2. The fatigue crack growth rate in air is obtained as the following equation. (dc/dN)$_{atr}$=7.23*10$^{-6}$ (.DELTA. K)$^{2.23}$ 3. The corrosion fatigue crack growth rate in environment is divided into three regions, that is, First Region, Second Region and Third Region from the small cyclic stress intensity. 4. The formation rate of the active surface on metal is slower than the mechano-chemical reaction rate in First Region. The crack growth rate depends on time and the cyclic stress intensity and is expressed as the following equation. (dc/dN)$_{I}$=C(/DELTA. K)$^{\delta}$ 5. The formation rate of the active surface is faster than the mechano-chemical reaction rate in Second Region and the synergistic effect by stress and corrosion becomes slow. In case the fatigue load is large, we have the critical crack growth rate which is not related to the cyclic stress intensity. 6. The corrosion crack growth rate by the mechano-chemical reaction is the same in $H_{2}$S $O_{4}$ solution and salt water, so Hydrogen accelerates the crack growth. 7. The environment has no effect on the corrosion fatigue crack growth rate in Third Region. 8. In First Region and Second Region, dimple is observed on the fatigue fracture surface in 0.1N $H_{2}$S $O_{4}$ solution. 9. The striation is observed in any environment as in air in Third Region and its interval approximately coincide with the crack growth rate.ate.e.e.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.573-580
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• 2012

Corrosion resistance and basic physical properties of solid tantalum are not comparable to most of the structural metallic materials. The relative high cost and melting temperature of tantalum are obstacles to be widely applied to general engineering processes. Electrodeposition in molten salt enables compact and uniform tantalum coating. In this study, Ta was coated onto base metal (SUS316L) with different current densities (0.5, 5, $20mA/cm^2$) by using MSE (Molten Salt Electrodeposition). In this study, it showed that deposition efficiency and microstructure of Ta coating layer were strongly depended on current density. In the case of the current density of $5mA/cm^2$, densest microstructure was obtained. The current density above $5mA/cm^2$ caused non-uniform microstructure due to rapid deposition rate. Dense microstructure and intact coating layer contributed to significant corrosion resistance enhancement.

• Magazine of the Korean Society of Agricultural Engineers
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• v.9 no.2
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• pp.1301-1305
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• 1967

Ground water flow can be studied with model test. Model test of ground water works are necessary for economic and safe design of the works. Also influence of the ground water flow to the durability and safety of hydraulic structures can be studied with this model. a. Sand model ; Water flow through porous media is the principle of sand model. Darcy's formula is the basic equation, $q=k{\frac{dh}{ds}}^{\circ}. The effect of the ground water flow on the grain system itself is represented with this model only. b. Hele-Shaw model ; In this model use is made of the viscous flow analogy. Viscous fluid such as glycerine flowing through two parallel plates depends on Poiseuille law, $q=-c{\frac{dh}{ds}}$. The analogue can be used vertically and horizontally. c. Heat model ; This is based on the analogy of the Fourier's law for heat conduction and Darcy's law for ground water flow. Especially unsteady problem can be studied with this model. A difficulty of the construction of this model is the isolation, which has to prevent losses of the heat. d. Electirc model ; Ohm's law for electric current is analogous to Darcy's law. Resistance material such as metal foil, graphite block, water with salt added, gelatine with salt added, ete. is connected to electric sources and resistor, and equi-voltage line is detected with galvanometer, $N_aCl$, $CuSo_4$, etc. are used as salt in the model. e. Membrane model ; This model is based on the facts that the deflection of a thin membrane obeys Laplace's equation if there is no load in the direction perpendicular to the membrane, and if the dellection is small.

• Membrane Journal
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• v.22 no.6
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• pp.424-434
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• 2012

In this study, a ceramic membrane was prepared by CVD. Tube type alpha alumina support was used for substrate and added the Ga salt in intermediate layer. Synthesized method was counter diffusion CVD method at $650^{\circ}C$ with tetramethylorthosilane (TMOS). Gas permeation was measured at $600^{\circ}C$ using single-component $H_2$, $N_2$, $CO_2$ and $CH_4$. During the steam treatment, $H_2/N_2$ permselectivity of non-Ga silica membrane was decreased 926 to 829 at $600^{\circ}C$. On the other hand $H_2/N_2$ permselectivity of added Ga silica membrane was stable 910 to 904 at $600^{\circ}C$. These results show that the metal-doped membranes improved steam stability for gas separation.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.431-445
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• 1993

The purpose of this study was to observe corrosion characteristics of six dental amalgams and was to analyse corrosion products electrochemically. After each amalgam alloy and Hg was triturated as the direction of the manufacturer by using mechanical amalgamator, the triturated mass was inserted into the cylinderical metal mold ($12{\times}10mm$) and was condensed with 160kg/$cm^2$ by using the hydrolic press. The specimen was removed from the mold and was stored at room temperature for 1 week, and was polished with amalgam polishing kit. The anodic and cathodic polarization curve was obtained by using cyclic voltammetric method with 3-electrode potentiostat in saline for each amalgam and Ag, Sn, Cu plate specimen at $37{\pm}0.5^{\circ}C$. The potential sweep range was -1.7V~0. 4V(vs SCE) in working electrode and scan rate was 50mV/s and the exposed surface area of each specimen to the electrolytic solution was $0.79cm^2$. The results were as follows. 1. In anodic-cathodic polarization curve of amalgam specimens, two anodic current rising areas and two cathodic current peaks were obtained at the low Cu amalgam(CF, CS) specimen and three anodic current rising areas and three cathodic current peaks were obtained at the high Cu amalgam (TY, DS, HV) specimen. 2. As this compared with the anodic and cathodic current peak potentials of Sn, Cu and Ag specimen, the first cathodic current peak I c was caused by the reduction of divalent tin salt, second cathodic current peak IIIc results from the reduction of quadravalent tin salt, and third cathodic current peak me results from the reduction of copper salt. 3. As reverse potential sweeping was done repeatedly, anodic current was decreased slightly in all amalgam specimens.

• Resources Recycling
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• v.18 no.3
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• pp.62-68
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• 2009

Continuous operation for 24h was carried out to establish the optimum condition at the magnesium fused salt electrolysis using a self made 150 ampere mono-polar type cell. An electrolyte composition of $MgCl_2$ 25%, NaCl 55%, $CaCl_2$ 19%, $CaF_2$ 1% was electrolyzed with applied voltage 7V, cathode current density $0.7-0.75A/cm^2$, electrode distance 6cm at $720{\sim}740^{\circ}C$ for 24 hours. Changes of applied current, composition of the electrolyte, current efficiency were investigated. Through the experiments, there were not any operating troubles with the self-made electrolytic cell. Purity of the electrolyzed magnesium metal was above 99%, and 89% of current efficiency was achieved. Some basic data for scale-up of the magnesium electrolysis equipment which would be necessary for commercialization were obtained.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.1
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• pp.57-65
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• 2005

This study suggested a new method for the solidification of molten salt waste generated from the electro-metallurgical process in the spent fuel treatment. Using binary material system, sodium silicate and phosphoric acid, metal chlorides were converted into metal phosphate in the micro-reaction module formed by SiO$_{2} particles. The volatile element in the reaction module would little vaporized below 1100$^{circ}$C After the gel product was mixed with borosilicate glass powder and thermally treated at 1000$^{circ}$C, li exists as Li$_{3}$PO$_4$ separated from glass phase and, Cs and Sr would be incorporated into an amorphous phase from XRD analysis. In case of the addition of ZrCl$_{4}$ to the binary system, the gel products were transformed into NZP structure considered as an prospective ceramic waste form after heat-treatment above 700 $^{circ}$C. From these results, the gel-route pretreatment can be considered as an effective approach to the solidincation of molten salt waste by the confirmed process or waste form and this also would be an alternative method on the ANL method using zeolites in USA by the confirmation of its chemical durability as an future work.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.523-528
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• 2007

The objectives of this research are to investigate the mechanism of coagulation affecting UF, find out the effect of metal salt coagulant on membrane fouling. Either rapid mixing + UF or slow mixing + UF process caused much less flux decline. For PACl coagulant, the rate of flux decline was reduced for both hydrophilic and hydrophobic membrane than alum due to higher formation of flocs. In addition, the rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. In general, Coagulation pretreatment significantly reduced the fouling of the hydrophilic membrane, but did little decrease the flux reduction of the hydrophobic membrane. When an Al(III) salt is added to water, monomers, polymers, or solid precipitates may form. Different Al(III) coagulants (alum and PACl) show to have different Al species distribution over a rapid mixing condition. During the rapid mixing period, for alum, formation of dissolved Al(III) (monomer and polymer) increases, but for PACl, precipitates of $Al(OH)_{3(s)}$ increases rapidly. This experimental results pointed out that precipitates of $Al(OH)_{3(s)}$ rather than dissolved Al(III) formation is major factor affecting flux decline for the membrane.