• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.877-885
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• 2013

A seawater pipe of the engine room in the ships is being surrounded with severely corrosive environments caused by fast flowing of the seawater, containing aggressive chloride ion and high conductivity etc.. Therefore, the leakage of the seawater from its pipe have been often occurred due to its local corrosion by aggressive chloride ions. Subsequently, its leakage area is usually welded by AC shielded metal arc welding with various electrodes. In this study, when the sea water pipe is welded with several types of electrodes such as E4301, E4311, E4313 and E4316, a difference of the corrosion resistance on the welding metal zones was investigated using an electrochemical method, observing microstructure, measuring polarization behaviors and hardness. The weld metal zone welded with E4313 electrode exhibited the lowest value of hardness compared to other weld metal zones. In addition, its zone indicated also the best corrosion resistance than those of other weld metal zones. Furthermore, all of the weld metal zones revealed a relatively better corrosion resistance than those of the base metal zones. and also showed higher hardness than the base metal zones.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.207-208
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• 2000

Since trichloroethylene (TCE), dichloroethylene (DCE), and vinyl chloride (VC) arise from anaerobic degradation of tetrachloroethylene (PCE) and TCE, there is interest in creating aerobic remediation systems that avoid the highly toxic VC and cis-DCE which predonominate in anaerobic degradation. However, it seemed TCE could not be degraded aerobically without an inducing compound (which also competitively inhibits TCE degradation). It has been shown that TCE induces expression of both the toluene dioxygenase of p. putida F1 as well as toluene-p-monooxygenase of P.mendocina KRI. We investigated here the ability of PCE, TCE, and chlorinated phenols to induce toluene-o-xylene monooxygenase (ToMO) from P.stutzeri OX1. ToMO has a relaxed regio-specificity since it hydroxylates toluene in the ortho, meta, and para positions; it also has a broad substrate range as it oxidizes o-xylene, m-xylene, p-xylene, toluene, benzene, ethylbenzene, styrene, and naphthalene; chlorinated compounds including TCE, 1, 1-DCE, cis-DCE, trans-DCE, VC, and chloroform : as well as mixtures of chlorinated aliphatics (Pseudomonas 1999 Maui Meeting). ToMO is a multicomponent enzyme with greatest similarity to the aromatic monooxygenases of Burkholderia pickettii PKO1 and P.mendocina KR1. Using P.sturzeri OX1, it was found that PCE induces P.mendocina KR1 Using P.situtzeri OX1, it was found that PCE induces ToMO activity measured as naphthalene oxygenase activity 2.5-fold, TCE induces 2.3-fold, and toluene induces 3.0 fold. With the mutant P.stutzeri M1 which does not express ToMO, it was also found there was no naphthalene oxygenate activity induced by PCE and TCE; hence, PCE and TCE induce the tow path. Using P.putida PaW340(pPP4062, pFP3028) which has the tow promoter fused to the reporter catechol-2, 3-dioxygenase and the regulator gene touR, it was determined that the tow promoter was induced 5.7-, 7.1-, and 5.2-fold for 2-, 3-, 4-chlorophenol, respectively (cf. 8.9-fold induction with o-cresol) : however, TCE and PCE did not directly induce the tou path. Gas chromatography and chloride ion analysis also showed that TCE induced ToMO expression in P.stutzeri OX1 and was degraded and mineralized. This is the first report of significant PCE induction of any enzyme as well as the first report of chlorinated compound induction of the tou operon. The results indicate TCE and chlorinated phenols can be degraded by P.stutzeri OX1 without a separate inducer of the tou pathway and without competitive inhibition.

• Journal of Food Hygiene and Safety
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• v.24 no.4
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• pp.332-337
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• 2009

Most propionic acid is added to food (especially breads) as preservatives and its form is sodium or calcium salt. Most countries admitted propionic acid as food preservatives but a tolerance limit is somewhat different according to countries. Recoveries of the official method for propionates reported as 50.0~60.0%. Accordingly new rapid determination method for propionates was developed using formic acid added sodium chloride (5 g) and ether (formic acid : ether = 1 : 2) as the extraction solvent to improve the official method with the complex processes. Propionate was dissolved from the samples with formic acid omitting steam distillation and ion exchange procedure. Then propionate in formic acid was extracted with ether and sodium chloride again. A $1\;{\mu}l$ aliquot of the filtrate of ether was analyzed by gas chromatograph. Recoveries from sample A and B fortified with propionic acid sodium salt were 85.0 % and 90.0 %, respectively.

• Journal of Life Science
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• v.20 no.6
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• pp.838-844
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• 2010

A fibrinolytic enzyme of Streptomyces corcohrussi from soil sediment was purified by chromatography using DEAE-Sephadex A-50 and Sephadex G-50. The analysis of SDS-polyacrylamide gel suggested that the purified enzyme is a homogeneous protein and the molecular mass is approximately 34 kDa. The purified enzyme showed activity of 0.8 U/ml in a plasminogen-rich fibrin plate, while its activity in a plasminogen-free fibrin plate was only 0.36 U/ml. These results suggested that the purified enzyme acts as a plasminogen activator. The fibrinolytic activity of the enzyme under the supplementation of protease inhibitors, $\varepsilon$-ACA, t-AMCHA and mercuric chloride in the enzyme reaction was less than 24%, indicating that it could be modulated by the plasmin and/or fibrinogen inhibitors involved in the fibrinogen-to-fibrin converting process. As time passed, $Zn^{2+}$, a heavy metal ion, inhibited the activity to 34.1%. The optimum temperature of the purified enzyme was approximately $50^{\circ}C$ and over 92% of the enzyme activity was maintained between pH 5.0 and 8.0. Therefore, our results provide a potential fibrinolytic enzyme as a noble thrombolytic agent from S. corcohrussi.

• Polymer(Korea)
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• v.35 no.2
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• pp.106-112
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• 2011

Aromatic copolyamides were prepared and their applicability to proton exchange membrane was studied. The copolymers contain two segments; thermally stable and mechanically strong poly (p-phenylene terephthalamide) (PPTA), and easily processable and good film-forming polysulfone. For the copolymers, different ratios of amine-terminated sulfonated ether sulfone monomer, terephthaloyl chloride, and p-phenylene diamine were sequentially reacted. The obtained copolymers were mixed with trimethylolpropane triglycidyl ether (TMPTGE), thermally cured, and converted into proton exchange membranes for fuel cell application. The reactions at each step and the molecular characteristics of precursor copolymers were confirmed by $^1H$ NMR, FTIR, and titration. The performance of the membranes was measured in terms of water uptake and proton conductivity. The water uptake, ion exchange capacity (IEC), and proton conductivity of the membranes increased with the increase of sulfonated ether sulfone segment content. Membrane containing 60 mol% sulfonic acid sulfone segment showed 1.88 meq/g IEC value. Water uptake was limited less than 110 wt% and the highest proton conductivity was up to $7.4{\times}10^{-2}$ S/cm ($25^{\circ}C$, RH=100%).

• Land and Housing Review
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• v.4 no.1
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• pp.119-124
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• 2013

Generally, the characteristic of nanofiltration membranes were catagorized into charged membrane, sieve effect, interaction between membarnes and target solutes. This study aims to investigate the effect item of heavy metal separation with view of charge nanofiltration membranes. The experiments of nanofiltration were conducted by nanofiltration set-up with operational pressure of 0.24 MPa at $25^{\circ}C$ by using synthetic wastewater containing 0.1mg/L of Cr, Fe, Cu, Zn, As, Sn, Pb. Nanofiltration membranes rejected heavy metals much better than chloride, sulfate and TOC, of which concentration in synthetic wastewater was higher than that of heavy metals. To consider rejection characteristics of various metals by nanofiltration membranes, separation coefficient, which is the molar conductivity ratio of the metal permeation rate to the chloride ion or TOC permeation rate, was introduced. In spite of different materials and different nominal salt rejection of nanofiltration membrane used, the separation coefficients of metals were nearly the same. These phenomena were observed in the relationship between the molar conductivity and the separation coefficient for heavy metals.

• Journal of Conservation Science
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• v.31 no.2
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• pp.95-104
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• 2015

Excavated archaeological cast iron objects in improper storage are quickly corroded and disintegrated into block and powder finally. Hence desalination treatment which is a way of removing internal corrosive factors, especially chloride ion, is an important process. But desalination is often omitted or objects are dehydrated by alcohol because the destruction of objects could occur during desalting. Although current desalting methods mostly use an aqueous alkali solution, $OH^-$ ions of water could accelerate corrosion and broaden internal cracks cause of high surface tension. Therefore this study experimented desalting using ethyl alcohol, which is low surface tension, to investigate an effect of desalination. As a result, desalting using ethyl alcohol showed the similar or more effective results of desalting using water. In addition, as aspects of desalting safety, ethyl alcohol desalting method was smaller destruction of objects and extraction of Fe from the objects than the aqueous alkali solution. However, this study explored the possibility of desalting methods using organic solvent in fieldwork, so the results would provide basic date for making the safe and effective desalting method for archaeological cast iron objects through further experiments.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.75-87
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• 2007

Groundwater recharge rates were estimated and compared in a headwater catchment at the Gwangneung Supersite using three different methods: water-table fluctuation (WTF), mass balance, and hydrograph separation techniques. Data were obtained during the rainy season from June to September 2005. Two different WTF methods estimated the groundwater recharge rate as 25.9% and 23.6%. The mass balance calculation of chloride ions indicated recharge rates of 13.4% on average. Baseflow separation using chloride ion as a tracer from six storm hydrographs produced a 14.0% net baseflow rate on average. Because of the implicit assumption of a long-term steady state without storage change, recharge rates calculated by mass balance and hydrograph separation were smaller than those done with WTF methods, which include the amount of increased storage due to the water-level rise. Subsequently, the WTF method is superior to others in the estimation of groundwater recharge rate to comprehend the dynamic characteristics of the hydrologic cycle.

• Journal of the Korean Chemical Society
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• v.17 no.6
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• pp.428-433
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• 1973

The quantitative separations of a mixture containing equal amount of each anion such as Si(IV), As(V), P(V), S(VI), W(VI) and Cr(VI) are carried out by the elution through 20${\times}3.14cm^2$ column of anion exchange resin, Dowex 1${\times}$8. The eluents are a mixture of 0.07 M hydrochloric acid and 0.03 M sodium chloride (pH = 1.30) for Si(IV), As(V) and P(V) species, a mixture of 0.6 M sodium chloride and 0.3 M sodium hydroxide for S(VI), W(VI) and Cr(VI) species, and 0.1 N sodium sulfite (pH = 3.48) for P(V) and As(V) species. The subsidiary anions in a standard mixture such as Si(IV), As(V), S(VI), P(V) and W(VI) are separated together from large amount of Fe(III) by the elution through 30cm${\times}3.14cm^2$ column of the resin, Dowex${\times}$50w${\times}$12, using a mixture of 0.1 M sodium nitrate and 2 percent dimethylsulfoxide aqueous solution as an eluent. Si(IV), As(V), S(VI), P(V) and W(VI) eluted together are separated quantitatively under the same conditions as in the separations of the anion mixture. By the conditions obtained in the separations of the standard mixture, Fe(III) and all of the subsidiary anions in steel are quantitatively separated.

• Polymer(Korea)
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• v.36 no.2
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• pp.169-176
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• 2012

Based on our experience in developing resistive humidity sensor, interdigital gold electrodes with different fingers and gaps have been fabricated on a glass epoxy (GE) substrate using screen printing techniques. The basic structure of the electrode consisted of a 3-, 4- and 5-fingers with gaps of 310 and 460 ${\mu}m$. Gold electrode/GE was prepared by first printing silver nanopaste, followed by consecutive electroless plating of Cu, Ni and then Au. Copolymer of [2-(methacryloyloxy)ethyl] dimethyl benzyl ammonium chloride (MDBAC) and methyl methacrylate (MMA) was used as a humidity-sensing polyelectrolyte, which was fabricated by a screen printing method on the Au electrode/GE substrate. The flexible humidity sensor showed acceptable linearity between logarithmic impedance and relative humidity in the range of 20-95%RH, low hysteresis of 1.5%RH, good response and recovery time of 75 sec at 1 V, 1 kHz, and $25^{\circ}C$. Electrode construction had a significant influence on the humidity-sensing characteristics of polymeric humidity sensors. The activation energy between electrode and ion conducting polyelectrolyte plays an important role in explaining the differences of humidity sensing characteristics such as temperature dependence, sensitivity, linearity and hysteresis.