• The Korean Journal of Zoology
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• v.7 no.2
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• pp.1-5
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• 1964

Carbonyl compounds, glycine, ammonia, carbon dioxide and hydrogen have been identified in gamma-irradiated oxygenated aqueous solutions of triglycine. The reactions occurring in this system are postulated only by representing the initial process and the final products. The triglycine molecule undergoes a reaction to form an intermediate giving rise to carbonyl compounds and acid amides. These compounds are decomposed to acetamide, glycine, glyoxylic acid, formic acid, oxalic acid, ammonia, and carbon dioxide by free radical attack in the primary and/or secondary reactions. It is also possible that the unrecognized reactions may give rise to products formed by radical-radical combinations. Satisfactory material balance for all the products have to wait until the completion of a study now in progress.ogress.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.118-118
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• 2003

편의와 fresh-like quality를 선호하는 소비 경향에 맞추어 가공한 fresh-cut사과의 선도 연장을 위한 저해제를 탐색하였다. 실험에 사용된 사과는 박피하여 속심을 제거한 사과를 8조각으로 절단하여 저해제에 3분간 침지한 후 물기를 제거하고 각각 LDPE 포장지에 포장하여 실온에서 저장하면서 colorimeter와 rheometer를 이용하여 색도와 물성을 측정하였다. 저해제로는 1% ascorbic acid, citric acid, NaCl, MgCl$_2$, CaCl$_2$, KCl, CaSO$_4$, MgSO$_4$, $Na_2$SO$_4$, oxalic acid, calcium lactate, calcium citrate를 사용하였으며 천연저해제로는 건칡, 맥문동, 목향, Rhubarb, 당귀, 오약, 시체, 지각, 천문동, 청피, 계피, 구기자, 당귀, 진피, 감초, 녹차, 후추 등을 열수추출하여 사용하였다. 물리적인 변화는 시간이 경과함에 따라 감소하는 추세를 보였으며 일부 건조로 인해 texture의 증가를 나타내기도 했다. 처리에 따른 물리적인 변화로는 CaCl$_2$, NaSO$_4$, Cl, 시금치를 처리하였을 때 그 변화가 가장 작았으나 시금치의 경우 시금치로 인한 사과의 색변화로 관능적으로 좋지 않았다. 한약재는 목향, 당귀, 지각, 계피를 처리하였을 때 물리적인 변화가 가장 작았으나 시금치와 마찬가지로 처리 초기에 한약재 자체의 향과 색으로 인하여 관능적으로 좋지 못한 결과를 나타냈다. 갈변 정도를 나타내는 ΔE의 변화는 KCl과 CaCl$_2$, CaSO$_4$를 처리한 구에서 변화가 가장 작았으며 한약재를 처리하였을 경우 당귀, 천문동을 처리한 구에서 효과를 보였다. oxalic acid는 갈변저해에는 효과적이었으나 시간이 경과함에 따라 수분의 용출이 증가하였으며 물성의 변화도 컸다. 또한 ZnCl$_2$를 처리한 구에서는 이취 발생과 수분 용출이 컸으며 색의 변화도 컸다.

• Applied Biological Chemistry
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• v.24 no.2
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• pp.120-125
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• 1981

Organic acids of Kochuzang (red pepper paste) prepared from glutinous rice, polished barley, wheat flour and sweet potato were analyzed by a gas chromatography. Lactic, pyruvic, succinic, fumaric, malic, pyroglutamic and citric acid were identified. And trace amount of oxalic acid was found in the Kochuzang prepared from sweet potato. The dominant organic acid of all samples was pyroglutamic acid, followed by pyruvic and citric acid. The organic acids were lower in Kochuzang from wheat flour than in other samples. The contents of succinic and fumaric acid were highest in Kochuzang prepared from sweet potato and were lowest in polished barley Kochuzang.

• Journal of the Korean Society of Tobacco Science
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• v.28 no.2
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• pp.130-135
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• 2006

This study was carried out to improve the analytical methods for determination of organic acids in tobacco leaf by HPLC. The samples for HPLC analysis were pre-treated by means of SPE. The calibration curve for each acid was linear and $R^2$ values ranged from 0.9990 to 1.0000. The limit of detection were obtained from the calibration curves and their values were between 1.39 to $4.87{\mu}g/mL$. Recovery rates of organic acids were between 88.6 % to 98.5 %. The concentrations of organic acids among the various tobacco leaves were compared to the concentration of organic acids, were in the order oriental, burley, flue-cured tobacco. In the case of flue-cured and oriental tobacco leaves, the order of concentration of organic acids was malic acid, oxalic acid, citric acid. But in the case of burley tobacco leaves, the order of concentration of organic acids was citric acid, oxalic acid, malic acid.

• Journal of the Korean Chemical Society
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• v.38 no.4
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• pp.271-275
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• 1994

The photochemical reaction of aqueous ethanol saturated with argon and carbon monoxide has been investigated using 184.9 nm UV light. The photochemical reaction of $1{\times}10^{-2}$ M aqueous ethanol saturated with argon results in the formation on the acetaldehyde and 2,3-butanediol. The irradiation of the solution saturated with carbon monoxide causes the formation of carbonylation and carboxylation products such as ${\alpha}$-hydroxypropionaldehyde, formaldehyde, glyoxal, formic acid, oxalic acid and glyoxylic acid in addition to above two products. But in the case of concentrated ethanol solutions, the irradiation did not give carbonylation and carboxylation products. The initial quantum yields of the products were determined and probable mechanisms for the reaction were presented on the basis of product analysis.

• Journal of the Korean institute of surface engineering
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• v.23 no.1
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• pp.34-43
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• 1990

Al-Si piston alloys such as AlS10CuMg have been anodized to examine apossibility of forming a hard film aat relatively higher temperatures compard with those in conventional sulfuric acid processes. Three types of electrolytes have been employed in this study ; electrolyte A(15% H2SO4, $0^{\circ}C$), electrolyte B(12% H2SO4, 1% oxalic, $10^{\circ}C$), electrolyte C(tartaric acid 125g/L+oxalic 75g/L+aluminum sulfate 225g/L, $25^{\circ}C$). Hard anodisine process in electrolyte B at a current density of 1.54A/dm2 produced a harder film of VHN 396 at a relatibely low film forming voltage compared with those obtained in other electrolyte at equivalent current density. A liner relationship between hardness and abrasion resistance exists for Al-Si piston alloys. The hardness of anodized film decreasees with increasing silicon content in Al-Si alloys and also with bath temperature. The film hardeness of Na-modified alloy os higher than that of P-modified alloy due to its finer microstructre. The film on the silicon phase in Al-Si alloys is observed to be formed by lateral growth of oxide film nucleated at surroundings.

• Journal of Power System Engineering
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• v.5 no.1
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• pp.89-96
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• 2001

Decorative property of chromium deposition from oxalic acid bath containing chromium oxide and ammonium sulfate, has been examined over a wide range of bath compositions and plating conditions. The followings were determined as optimum bath composition, $CrO_3\;200{\sim}250g/{\ell},\;H_2C_2O_4{\cdot}2H_2O\;500{\sim}700g/{\ell},\;(NH_4){_2}SO_4\;40{\sim}120g/{\ell}$, and operation conditions; pH $2.0{\sim}2.5$, current density of $15{\sim}250Adm^2 $ at the bath temperatures of $30{\sim}80^{\circ}C$. Bright chromium deposits were obtained over a wide range of ammonium sulfate concentration, bath temperature, and current density. The current efficiency decreased with increasing current density and bath pH, and increased with Increasing bath temperature. The highest current efficiency was obtained in the bath containing $80g/{\ell}$ of ammonium sulfate. Bright chromium deposits were not obtained at conditions of all the highest current efficiencies.

• Food Science and Biotechnology
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• v.16 no.4
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• pp.650-654
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• 2007

Many vegetables contain oxalate at various levels depending on their type and family. Oxalate is known to reduce mineral bioavailability from foods. The following study was conducted to determine soluble and total oxalate contents in 32 plant samples commonly consumed in Korea using high-performance liquid chromatography (HPLC). Chard, amaranth, and spinach contained total oxalate of >1,000 mg/100 g. Approximately 45% of the oxalate in amaranth is insoluble, whereas 74.46 and 92.45% of the oxalates in chard and spinach, respectively, was soluble oxalates, which may be removed by blanching. Eggplant, carrot, leak, ginger root, spinach, burdock, and sweet pepper contained more than 90% soluble oxalate in total oxalate content. However, all oxalates detected in lettuce and celery were insoluble. Oxalate was not detected in shepherd's purse, bellflower root, garlic, radish root, broccoli, cabbage, onion, lotus root, adlay, cucumber, kale, and pumpkin. These observations provide useful information needed for selection of vegetables.

• Journal of the Korean institute of surface engineering
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• v.47 no.3
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• pp.121-127
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• 2014

In this study, in order to improve corrosion resistance and wear resistance of aluminum, surface treatment was made by anodizing with oxalic acid solution and sealing with nano-diamond powder. Average size of nano-diamond powder was 30nm. Anodizing with oxalic acid made many pores in the aluminum oxide layer. Pore size and oxide thickness were investigated by scanning electron microscope (SEM). Pore size increased as temperature increased and voltage increased. It was possible to make oxide layer with pore diameter more than 50 nm. Oxide thickness increased as temperature and voltage and treatment time increased. Oxide layer with above $10{\mu}m$ thickness was made. Aluminum oxide layer with many pores was sealed by water with nano-diamond powder. Surface morphology was investigated by SEM. After sealing treatment with nano-diamond powder, corrosion resistance, wear resistance and hardness increased.

• Korean Journal of Materials Research
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• v.28 no.2
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• pp.82-88
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• 2018

Stable slurries of YSZ in aqueous suspension with added polymer dispersants, namely, poly-methacrylic acid ammonium salt (PMMA), poly-acrylic acid (PAA) and poly-acrylic-co-maleic acid (PAMA), were mixed with the monomolecular dispersants citric acid and oxalic acid. The dispersion properties of the suspension were investigated using PSA, viscosity, sedimentation, and FT-IR. The polymer dispersants and monomolecular dispersants were attached to the YSZ surface by the carboxylic group, as shown by the FTIR results. A stabilized aqueous suspension was obtained when the polymer dispersant and citric acid were mixed and compared to the use of citric acid alone as a dispersant agent. When the polymer dispersant and citric acid were mixed and milled through attrition milling, there was a smaller particle size compared to when the polymer dispersant alone was used as a dispersant agent. This study determined that the particle size of the mixed dispersant was affected by the properties of the monomolecular dispersant and that the stability of the suspension was affected by the polymer dispersant. However, when slurries of YSZ were mixed with oxalic acid, the particle bridging behavior was the result of the high degree of viscosity and the small sedimentation height.