• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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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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• 제30권2호
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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.

• 오토저널
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• 제5권1호
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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.

• 한국수소및신에너지학회논문집
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• 제23권6호
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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.

• 한국농공학회지
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• 제9권2호
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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.

• 멤브레인
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• 제22권6호
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• pp.424-434
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• 2012

본 연구에서는 CVD법으로 세라믹 막을 제조하였다. 튜브의 ${\alpha}-Al_2O_3$ 지지체 위에 Ga 염이 첨가된 ${\gamma}-Al_2O_3$를 코팅하였고, 실란화합물인 tetramethylorthosilane (TMOS) 를 $650^{\circ}C$에서 화학적 기상 증착법으로 막에 증착하였다. 제조된 세라믹 막을 사용하여 수소, 질소, 이산화탄소, 메탄의 단일조성 기체투과 실험을 $600^{\circ}C$에서 시행하였다. Ga 염 비첨가 시, $600^{\circ}C$ 수분 처리 실험의 $H_2/N_2$ 선택도가 926에서 829로 감소한 반면, Ga 염 첨가 시에는 910에서 904로 안정하였다. 이 결과를 통해, 막에 금속염을 첨가하여 제조한 막이 수분 안정성을 향상시킴을 확인하였다.

• Restorative Dentistry and Endodontics
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• 제18권2호
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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.

• 자원리싸이클링
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• 제18권3호
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• pp.62-68
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• 2009

마그네슘 용융염 전해시 적정 조업조건을 확립하고자 자체 설계 제작한 150A급 mono-polar형 전해조를 사용하여 24시간 연속 전해 조업을 수행하였다. $MgCl_2$ 25%, NaCl 55%, $CaCl_2$ 19%, $CaF_2$ 1%의 전해욕 조성으로 전해온도 $720{\sim}740^{\circ}C$, 전해전압 7V, 음극 전류 밀도 $0.7-0.75A/cm^2$, 전극 간격 6cm의 운전조건에서 24시간 연속 조업을 수행하였으며, 전해 전압 및 전류 변화, 전해 욕 조성 변화, 전류 효율 등을 조사하였다. 시험결과 제작한 전해셀의 조업성이 양호하였으며, 순도 99% 이상의 금속 마그네슘을 회수하였고 전류효율 89%를 달성할 수 있었다. 본 연구를 통하여 마그네슘 용융염 전해장치 제작에 필요한 기초자료를 축적할 수 있었다.

• 방사성폐기물학회지
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• 제3권1호
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• pp.57-65
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• 2005

본 연구는 사용 후 핵연료의 금속전환 공정에서 발생되는 폐용융염을 고형화하는 방법으로 GRSS(Gel-Route Slabilization/Solidifcation)개념을 이용한 전처 리법을 제안하였다. Sodium silicate와 H3p04로 구성된 물질계에서는 SiO$_2$에 의해 형성되는 반응모듈 내에서 휘발성 핵종은 열적으로 안정한 화합물로 전환된다. 얻어진 생성물은 붕규산 유리매질과의 반응을 통하여 Li는 Li$_{3}$PO$\_4$ 형태로 유지되며 Cs 및 Sr은 유리매질내에 포용될 수 있다. 또한 sodium silicate, H$_{3}$PO$_4$ 및 ZrCl$_4$로 이루어진 물질계를 이용하여 내구성이 우수한 WZP 세라믹 고화매질을 합성하였다. $700^{circ}C$이상에서 NZP구조가 형성되며, Cs가 Li보다 우선하여 NZP구조를 형성하였다. 이상의 결과로부터, GRSS를 이용한 폐용융염의 전처리는 단순한 공정과 열적 안정성을 통하여 검증된 고화매질로 고형화가 가능토록하는 유효한 접근법이라 할 수 있으며, 수화학적 안정성의 검증을 통하여 ANL의 제올라이트를 이용한 고화법에 대한 대안이 될 것으로 기대된다.

• Korean Chemical Engineering Research
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• 제45권5호
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• pp.523-528
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• 2007

본 연구에서는 막분리 공정의 전처리 공정으로 응집 공정을 적용할 경우 응집 공정의 적용 가능성을 평가하고자 하였으며 사용된 응집제 종류에 따라 발생하는 금속염이 막오염에 미치는 영향을 파악하고자 하였다. 응집제 종류에 따른 투과 flux 실험결과 응집 공정을 전처리 공정으로 적용할 경우 막의 재질에 상관없이 응집효율이 우수한 PACl의 경우 투과 flux가 높게 나타났으며 전처리 응집 공정의 적용시 급속교반+UF 공정에 비하여 급속-완속교반+UF 공정의 경우 투과 flux 감소율이 낮게 나타났다. 급속교반 공정에 응집제를 첨가할 경우 다양한 형태의 가수분해종이 형성되어졌으며 금속염 응집제가 막오염에 미치는 영향을 살펴보기 위하여 시간에 따른 투과 flux 실험결과 금속염 응집제에 의한 막오염이 발생하였으며 응집제 주입량이 증가할수록 침전물 형태의 금속염 가수분해종의 발생이 증가하여 투과 flux 감소가 크게 나타났다.