• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.401-401
• /
• 2011

In this work, we deposited Al2O3doped ZnO (AZO) thin films by direct current (DC) magnetron sputtering method with a $40^{\circ}$ tilted target, for application in the front layer of thin film solar cell. Wet chemical etching behavior of AZO films was also investigated. In order to optimize textured AZO films, oxalic acid ($C_2H_2O_4$)has been used as wet etchant of AZO film. In this experiment we used 0.001% concentration of oxalic acid various etching time, that showed an anisotropy in etching texture of AZO films. Electrical resistivity, Hall mobility and carrier concentration measurements are performed by using the Hall measurement, that are $6{\times}10^{-4}{\Omega}cm$, $20{\sim}25cm^2/V-s$ and $4{\sim}6{\times}10^{20}$, respectively.

• The Microorganisms and Industry
• /
• v.26 no.1
• /
• pp.18-30
• /
• 2000

Three kinds of organic matter such as glucose, oxalic acid, and ethanol were added to the media(N-free or NO$\_$3/-riched) and their effects on the nitrogen fixation of Nostoc pruniforme were measured by manometric technique through the experiments in vivo. 1) The organic matters used in this experiments showed effective results as a role of substrate for the fixation of atmospheric nitrogen. 2) In the nitrogen-free medium treated with the both of flucose nad ethanol, the highest nitrogen uptakes were detected in the treated of low concentrations (glucose ; 0.1%, 0.5%, ethanol : 0.1%, 0.5%). On the contrary, the highest nitrogen uptakes in NO$\_$3/-riched medium were measured at the treated of high concentrations (glucose ; 2%, 1%, ethanol ; 1.5%, 1.0%). 3) The highest nitrogen uptakes in N-free medium treated with oxalic acid were measured at the concentration of 2% and 1%, respectively. In the medium of NO$\_$3/-riched, the nitrogen uptakes were in the opposite directions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.5
• /
• pp.415-420
• /
• 2008

AAO films were fabricated on two kinds of substrates such as $Al/SiO_2/Si$ and Al/Ni/Ti/Si. To obtain well-aligned AAO film, we optimized process condition for buffer layer, electrolyte and voltage. In the case of oxalic acid, the AAO film with pore size of approximately 45 nm was obtained at voltage of 40 V, temperature of $10^{\circ}C$, oxalic acid of 0.3 M and widening time of 60 min. Then the thickness of barrier is less than 600 nm. In the case of sulfuric acid, the AAO film has pore size of 40 nm and barrier thickness of 400 nm with optimum conditions such as voltage of 25 V, temperature of $8^{\circ}C$, sulfuric acid of 0.3 M and widening time of 60 min.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.227-230
• /
• 2004

As the organic acids were added in the slurry, zeta potential of alumina was changed to negative value and IEP value was shifted from alkaline to acidic pH. In citric acid based slurry, Cu surface continuously dissolved and etching depth linearly increased. On the contrary, passivation layer was grown on Cu surface in oxalic acid based slurry. As the platen rotation speed increased, Preston coefficient decreased in both slurries. With oxalic acid based slurry, at low velocity, removal rate is high value because of high friction force compared to citric acid based slurry. As platen velocity increased, removal of Cu in citric acid based slurry became higher value than oxalic acid based slurry. Typical lubrication behaviors were observed in both slurries. As Sommerfeld number increased, COF values gradually decreased and then re-increased. It indicated that lubrication was changed to direct contact or semi-direct contact mode to hydro-lubrication mode.

• Journal of Surface Science and Engineering
• /
• v.56 no.3
• /
• pp.169-179
• /
• 2023

This work studies dielectric breakdown behavior of AAO (anodic aluminum oxide) films formed on pure aluminum at a constant current density in 5 ~ 20 vol.% sulfuric acid (SA) and 2 ~ 8 wt.% oxalic acid (OA) solutions. It was observed that dielectric breakdown voltage of AAO film with the same thickness increased with increasing concentration of both SA and OA solutions up to 15 vol.% and 6 wt.%, respectively, above which it decreased slightly. The dielectric breakdown resistance of the OA films appeared to be superior to that of SA films. After dielectric breakdown test, cracks and a hole were observed. The crack length increased with increasing SA film thickness but it did not increase with increasing OA film thickness. To explain the reason why shorter cracks formed on the OA films than the SA films after dielectric breakdown test, the generation of tensile stresses at the oxide/metal interface was discussed in relation to porosity of AAO films obtained from cross-sectional morphologies.

• 보존과학연구
• /
• s.31
• /
• pp.43-57
• /
• 2010

This study intends to provide quantitative data about the extraction characteristics of major elements of earthenware by executing soaking test of cleaning agents. It aims at providing basic data for the stability assessment when applying the cleaning agents for conserving earthenware. The data will be extracted from the analysis of co-relationship between the physical characteristics and the ion extraction characteristics. XRD analysis displayed that AT-1, AT-2 and AT-3 which did not generate mullite were fired at lower than 1,000 whereas AT-3 and AT-5 that included mullite were higher than 1,000. The degree of absorption was AT-4 > AT-2 > AT-1 > AT-3 > AT-5 in order and the correlation between the degree of absorption and firing temperature of earthenware displayed a positive correlation. Extraction amount of oxalic acid which was used for the removing iron oxide was AT-1 > AT-2 AT-4 > AT-3 > AT-5 in order. and the ion extraction data displayed that there is a positive correlation with absorption level. However AT-1 and AT-2 which were fired at lower temperature showed that there was no correlation between the ion extraction characteristics and absorption level. Ion extraction of citric acid produced little amount compared with the one of oxalic acid, yet it caused less damage to earthenware than oxalic acid when it applied. The result of ion extraction level in the absorption test displayed that Fe had higher level than in Si, Al from the test for both oxalic acid and citric acid. Based on the regression analysis of the data from the previous studies, the physical characteristics of the earthenware and ion extraction level, further studies will be conducted on the predicting technique on the extraction characteristics of major elements of earthenware samples for the conservation in future.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.1
• /
• pp.78-84
• /
• 1993

This study was conducted to investigate the effect of various polyethylene (PE) film packaging on the quality of strawberry during storage at low temperature. Gas composition in film was changed rapidly at early stage of storage and then kept at the level of 5~10% $CO_2$and 1~3% $O_2$. Weight loss and decay rate were low at 0.08mm PE film packed strawberries. Titratable acidity, pH and soluble solids were changed slightly during storage but its large difference according to film thickness was not observed. Decrease of flesh firm-ness and a value was restrained by PE film packaging. Free sugar of strawberry was composed of glucose and fructose in similar content and it was decreased a little during storage but the difference according to film thickness was not observed. The organic acids in strawberry were citric acid, malic acid, succinic acid, ascorbir acid, oxalic acid, tartaric acid and pyruvic acid and the major organic acid was citric acid. The contents of citric acid, malic acid, succinir acid and ascorbic acid were decreased and oxalic acid and tartaric arid were not changed during storage but pyruvic acid was increased in early stage and then decreased. These changes of organic acid were slight in packaged with 0.08mm PE film strawberry.

• Food Industry And Nutrition
• /
• v.7 no.2
• /
• pp.40-44
• /
• 2002

매실의 향기성분은 50여종 중 알콜류가 benzyl alcohol, linalool, 1,6-octadien-3-ol, n-haxanol 등 10종, aldehyde류가 2-hexenal, benzaldehyde, n-hexanal 등 3종, acid류가 butandeionic acid, acetic acid, 2종, 2-iodo-hexane 등 hydrocarbon류가 5종, butanedioic acid-diethyl estet를 포함한 ester류가 3종, B-ionone을 포함한 ketone류가 3종 그리고 기타 성분이 2종이었다. 매실이 성숙함에 따라 향기성분의 수가 증가하고 그 함량도 증가하는 경향이었다. 매실의 비휘발성 유기산의 조성은 succinic, fumaric, oxalic, malic, tartaric 및 citric acid이었다. 매실이 비휘발성 유기산은 성숙 초기에는 malic acid와 oxalic acid의 함량이 높았다. Citric acid의 함량이 증가한 반면에 대부분의 유기산은 감소하는 경향이었다. 휘발성 유기산은 성숙중에 formic acid함량은 감소하고 butyric acid의 함량은 증가하는 경향이었다. 총 유기산의 함량은 매실 성숙에 현저히 감소하는 경향이었다.

• Journal of Korean Society on Water Environment
• /
• v.22 no.5
• /
• pp.871-878
• /
• 2006

Batch experiments were performed to evaluate the applicability of soil washing for heavy metal contaminated soils at Nacdong and Hamchang abandoned mines. The texture of the Nacdong soil was sandy loam. Nacdong abandoned mine soil was almost neutral (pH=6.5). Contaminations of As, Cd, Pb and Zn for Nacdong mine soils were 12,900 mg/kg, 29 mg/kg, 696 mg/kg and 276 mg/kg, respectively. Hamchang abandoned mine soils were acidic (pH=2.6) and the soil texture was loam. The contaminations of As, Cd, Pb and Zn for Hamchang abandoned mine soils were 6,410 mg/kg, 291 mg/kg, 1,300 mg/kg and 1,110 mg/kg, respectively. For the Nacdong abandoned mine soils, oxalic acid was found to be the most effective soil washing extracter for As and Pb while citric acid was the most effective extracter for Cd. For the Hamchang abandoned mine soils, oxalic acid showed the highest extraction efficiencies for As and Pb, whilst citric acid presented the best soil washing efficiencie for Cd. Oxalic acid and EDTA were found to be the most effective soil washing extracter for the Hamchang abandoned mine contaminated soils.

• Food Science and Preservation
• /
• v.6 no.4
• /
• pp.495-499
• /
• 1999

The free sugars in leaf and root of dandelion were composed of sucrose, glucose and fructose. The contents of total free sugars was higher in root than those in leaf. The oxalic acid, citric acid and malic acid contents of leaf was 45.4, 3.6, 2.7mg/100g-f.w., respectively. And the oxalic acid, citric acid and malic acid contents of root was 34.6, 2.1, 1.6mg/100g-f.w., respectively. Total free organic acid content of leaf was higher than that of root. The major free amino acids of dandelion were aspartic acid, serine, asparagine, glutamic acid, glycine, valine, isoleucine and content of glutamic acid was highest in free amino acids. The contents of vitamin A in leaf and root of dandelion was 135.4 and 34.1$\mu\textrm{g}$/100g-f.w., respectively. The contents of vitamin C in leaf and root of dandelion was 67.4 and 4.6 mg/100g-f.w., respectively.