• Journal of the Korean Wood Science and Technology
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• 제32권2호
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• pp.1-8
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• 2004

갈색부후균 Tyromyces palustris를 이용하여 CCA처리 목재와 CCFZ처리 목재에서 중금속을 제거하였다. 전처리 방법으로써 증기압처리와 수산처리가 검토되었다. 수산 전처리에 의한 균처리의 제거율 상승 영향과 일정 균체량에 대한 방부처리재의 폭로양의 차이에 따른 처리율의 변화정도를 검토하였다. 배양방법을 달리하여 방부처리재의 유효성분 제거량을 비교하고 생물반응기를 이용하여 중금속 제거를 실시하였다. 크롬과 비소는 수산의 농도가 증가할수록 제거율이 증가하였으나 구리는 농도의 증가에 따른 제거율이 크게 향상되지 않았다. T. palustris는 균체량 287 mg으로 크롬과 비소는 시료무게 3 g까지 60% 이상의 제거율을 나타냈고 구리는 50% 이상의 제거율을 나타내었다. 진탕배양에서는 크롬, 구리, 비소의 제거율이 60% 이상의 제거율을 보였으며, 정치배양에서는 구리의 제거율이 진탕배양보다 높게 나타났다. 생물반응기 적용 시 7일 배양이후 제거율은 크롬 72%, 구리 61%, 비소는 59%이었다.

• 한국수산과학회지
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• 제43권6호
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• pp.573-580
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• 2010

The study investigated the effect of diets supplemented with different levels (0 and 2.5%) of yuza (Citrus junos Sieb ex Tanaka) on the nutritional characteristics of eels (Auguilla japonica). Fish ($9.8{\pm}1.3g$) was fed to apparent satiation twice daily for 8 months. There were no significant differences in proximate composition among the treatment groups, except for the ash and carbohydrate contents (P<0.05). The vitamin C content of eel muscle in the yuza-added group was two-times higher than in non-added groups (P<0.05). Among eight organic acids in eel muscle, lactic acid was predominant, followed by citric acid, oxalic acid, malic acid, and acetic acid. Eels fed a 2.5% yuza diet had the highest lactic acid content in all groups. Six sugars were found in all groups and glucose was the major sugar. Glucose and maltose were the dominant sugars in the yuza-added group. The abundant fatty acids in the yuza-added group were C18:1 n-9, C16:0, and C16:1 n-7, which comprised over 80% of the total fatty acids. The major amino acids in samples were glutamic acid, aspartic acid, lysine, and leucine. There were few differences in the free amino acid compositions among the groups. However, histidine was the predominant amino acid and constituted over 53% of the total free amino acids.

• 한국세라믹학회지
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• 제31권11호
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• pp.1401-1413
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• 1994

The synthesis of kaolinite mineral from domestic diatomite for silica resource, commercial vailable gibbsite or alumina for alumina resource were made under various hydrothermal treatment, and the sythetic effect of acidic mineralizers, temperature treatment with time duration, particle size of alumina on formation of kaolinite mineral and the plastic properties of synthesized kaolinite were investigated. The various acidic mineralizers which are HCl, HNO3, H2SO4 and Oxalic acid were employed for hydrothermal reaction in the range of 0.01 mol/ι to 2 mol/ι concentration of each mineralizers. It was found that HCl in the level of 1 mol/ι solution produced highly yields of well-crystallized and platy form kaolinite mineral and gave the most effective extraction of iron oxide, compared to that of others, that HNO3 produced highly yield of kaolinite but lower extraction of iron oxide, that H2SO4 produced low yield of kaolinite and formed alunite mineral, and that oxialic acid formed spherical crystalline kaolinite and gave low extraction of iron oxide. Moreover, it showed that kaolinite minerals were well synthesized in a wide range of less than 2 mol/ι acids, but were poorly synthesized at more than 2 mol/ι acids. However, boehmite and kaolinite were coexistently formed in the temperature range of 18$0^{\circ}C$ and 20$0^{\circ}C$ when the calcined diatomite and gibbsite were involved. The well-ordered kaolinite mineral as a platy form was highly synthesized in the temperature range of 220 and 24$0^{\circ}C$, when the same marterials as above were used with treatment of 1 mol/ι HCl solution. The results also revealed that the size of crystalline platy form kaolinite, synthesized from alumina and calcined diatomite with treatment in 1 mol/ιHCl solution at 24$0^{\circ}C$, was much larger than that of gibbsite and calcined diatomite shown previously, and that kaolinite and corundum minerals were coexistently formed under any hydrothermal treatment conditions. The plasticity of synthesized kaolinite from under 2 ${\mu}{\textrm}{m}$ alumina and calcined diatomite was very poor, and that of the synthesized kaolinite from raw diatomite and gibbsite gave higher than that of calcined diatomite and gibbsite.

• 유기물자원화
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• 제17권4호
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• pp.59-65
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• 2009

돼지의 장 및 분변에서 분리한 14종의 유산균으로부터 항세균 활성물질을 분석하였다. 각 균주의 세포배양액을 대상으로 여러 종류의 단백질 분해효소와 열, 알칼리 처리 등을 수행한 후 활성도를 조사한 결과, 효소 및 열처리 시료에서는 활성도가 유지되었으나, 1M의 NaOH로 중화 처리한 시료에서는 활성도가 사라짐에 따라, 항세균 활성물질이 단백질성이라기보다 유기산일 가능성이 큰 것으로 나타났다. Sep-pak $C_{18}$ Cartridges을 이용한 음이온 추출실험과 Bio-LC system을 이용한 high performance anion exchange chromatography를 실시하여 물질을 정제한 결과, 주요 활성물질로 옥살산, 구연산, 젖산 및 초산 등, 4종류의 유기산이 검출되었다. 이중 젖산은 각 균주에 따라 전체 유기산의 54~77%를 차지하는 것으로 나타나 유기산 중에서도 일차적인 항세균 활성물질일 것으로 추정된다.

• 대한치과보철학회지
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• 제44권4호
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• pp.443-454
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• 2006

Purpose: This study aims to get the fundamental data which is necessary to the development direction of implant surface treatment hereafter, based on the understanding the surface structure and properties of titanium which is suitable for the absorption of initial tissue fluid by researching effects of additional surface treatments fir sandblasted with large git and acid-etched(SLA) titanium on surface micro-roughness, static wettability, fibronectin adsorption Materials and Method: In the Control groups, the commercial pure titanium disks which is 10mm in diameter and 2mm in thickness were treated with HCI after sandblasting with 50$\mu$m $Al_2O_3$. The experiment groups were made an experiment each by being treated with 1) 22.5% nitric acid according to SLA+ASTM F86 protocol, 2) SLA+30% peroxide, 3) SLA+NaOH, 4) SLA+ Oxalic acid, and 5) SLA+600$^{\circ}C$ heating. In each group, the value of Ra and RMS which are the gauges of surface roughness was measured, surface wettability was measured by analyzing with Sessile drop method, and fibronectin adsorption was measured with immunological assay. The significance of each group was verified by (SPSS, ver.10.0 SPSS Inc.) Kruskal-Wallis Test. (α=0.05) And the correlation significance between Surface micro-roughness and surface wettability. surface roughness and fibronectin adsorption, and surface wettability and fibronectin adsorption was tested by Spearman's correlation analysis. Result: All measure groups showed the significant differences in surface micro-roughness, surface wettability, and fibronectin adsorption. (p<0.05) There was no significance in correlation among the surface micro-roughness, surface wettability, and fibronectin adsorption. (p>0.05) Conclusion: Surface micro-roughness and surface wettability rarely affected the absorption of initial tissue fluid on the surface of titanium.

• 상하수도학회지
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• 제21권5호
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• pp.559-569
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• 2007

The purposes of this study were to find the main foulant of membrane and the optimal chemical cleaning method for MF(microfiltration) drinking water treatment system using D dam water as water source. The MF pilot plant which can treat maximum $500m^3/d$ consisted of 3 racks and was operated for 10 months under various operation conditions. After 10 months operation, $1^{st}$ and $2^{nd}$ rack of membrane pilot plant system were cleaned chemically and the degree of the restoration of the fouled membrane in terms of the pure water flux was detemnined. Inorganic compounds which contained in chemical cleaning waste was analyzed by Inductively Coupled Plasma (ICP). One membrane module for 3rd rack was disjointed and membrane fouling materials, especially inorganic compounds were investigated by Electron Probe Microanlysis (EPMA) to elucidate the reason of TMP increase. And also, the various chemical reagents (1N HCl or $H_2SO_4$, oxalic acid as acid and 0.3% NaOCl as alkali) were tested by combination of acid and alkali to determine the optimal chemical cleaning method for the MF system using micro-modules manufactured using the disjointed module. It was verified that the inside and outside of membrane module was colorized with black. As a result of the quantitative and semi-qualitative analysis of membrane foulant by ICP, most of inorganic foulant was manganese which is hard to remove by inorganic acid such as HCI. Especially, it was observed by EPMA that Mn was attached more seriously in inside surface of membrane than in outside surface of that. It was supposed that Mn fouling in inside surface of membrane might be caused by the oxidation of soluble manganese (Mn(II)) to insoluble manganese ($MnO_2$) by chlorine containing in backwashing water. The optimal cleaning method for the removal of manganese fouling was consecutive cleaning with the mixture of 1N HCl and 1% of oxalic acid, 0.3% NaOCl, and 1N HCl showing 91% of the restoration of the fouled membrane.

• 한국생산제조학회지
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• 제22권3호
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• pp.372-379
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• 2013

In this study, we investigated the traits of the clad metals used in hot-rolled clad steel plates. We examined the sensitization and mechanical properties of STS 316 steel plate and carbon steel (A516) under the specific circumstances of post heat treatment and whether a weld was multilayered and thick or repeated because of repairs. The test conditions were as follows. The clad steel plates were butt-welded using FCAW/SAW, and the heat treatment was conducted at $625^{\circ}C$, for 80, 160, 320, 640, or 1280 min. The change in the corrosion resistance was evaluated in these specimens. In the case of the carbon steel (A516), as the heat treatment time increased, the annealing effect caused the tensile strength to decrease. The micro- hardness gradually increased and then decreased after 640 min. The elongation and contraction of the area increased gradually. An oxalic acid etch test and EPR test on STS316, a clad metal, showed a STEP structure and no sensitization. From the test results for the multi-layered and repair welds, it could be concluded that there is no effect on the corrosion resistance of clad metals. In summary, the purpose of this study was to suggest some considerations when developing on-site techniques and evaluate the sensitization of stainless steels.

• 한국문화재보존과학회:학술대회논문집
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• 한국문화재보존과학회 2005년도 제22회 학술대회 발표 논문집
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• pp.100-103
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• 2005

Lichens play an important role in breaking down rocks physically and chemically. Physical weathering occurs mechanically through hyphae and rhizines growing into the rocks. Lichen substances such as oxalic acid, acidic polysaccharides and depsides may assist altering rocks chemically. These actions partly contribute to soil formation but prove harmful for the substratum. Some people do not like to keep lichens on stained glassof churches or on gravestones mainly because of its unglamorous appearance. A biocide, 'Koretrel', is very effective in removing lichens and blue-green algae from the surface of concrete. After spraying 'Koretrel' in the open air, lichens (Caloplaca sp., Endocarpon petrolepideum, Physciella melanchra, Phaeophyscia hispidula, etc.) growing on buildings died within three months and peeled off fromthe substratum. One year after treatment, concrete surfaces were almost lichen free for three or four years. The biocide makesuse of a kind of lichen substance and harmless both for substances and environment. Our recent experiments show that it is also useful for water grasses growing on the surface of an aqueduct of a hydroelectric power station.

• Journal of Welding and Joining
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• 제13권3호
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• pp.89-95
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• 1995

Effect of boron on corrosion resistance of Type 304 stainless steel has been studied. Boron tends to segregate at the grain boundaries during cooling after solution treatment, and so boron treated steel usually exhibits a ditch structure under the 10% oxalic acid test. However, it was found that the addition of 25 ppm boron in Type 304 steel has no effect on the general and pitting corrosion resistance while it has a little effect on the intergranular corrosion resistance.

• 한국표면공학회지
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• 제51권6호
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• pp.372-380
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• 2018

Anodization techniques are widely used in the area of surface treatment of aluminum alloys because of its simplicity, low-cost and good corrosion resistance. In this study, we investigated the relationship between the properties (porosity and thickness) of anodic aluminum oxide (AAO) and its corrosion behavior. Aluminum 5052 alloy was anodized in 0.3 M oxalic acid at $0^{\circ}C$. The anodizing of aluminum 5052 was performed at 20 V, 40 V and 60 V for various durations. The corrosion behavior was studied in 3.5 wt % NaCl using potentiodynamic polarization method. Results showed that the pore diameter and thickness increased as voltage and anodization time increased. The relatively thick oxide film revealed a lower corrosion current density and a higher corrosion potential value.