• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.414-417
• /
• 2001

This research was compared the amount of phosphate solublized by Pantoea agglomerans which can solublize the insoluble phosphate salt hydroxyapatite with the phosphate produced by being treated with various acids. When P. agglomerans grows in the BY medium containing potassium dihydrogenphosphate of phosphate source without hydroxyapatite, it consumed 361mg/L phosphate, during 72hours cultivation. When 4% hydroxapatite was treated with 0.01N citric acid and oxalic aicd, the amount of solublized phosphate was 702mg/L and 537mg/L more than that by P.agglomerans. The maximum amount of solublized phosphate by P. agglomerans was 465mg/L after 48 hours cultivation.

• Journal of the Korean Chemical Society
• /
• v.25 no.4
• /
• pp.270-274
• /
• 1981

Al(III) and Cr(III) were determined selectively by colorimetry of Bismark Brown R {4,4'[(4-methyl-1,3-phenylene)bis(azo)]-bis(6-methyl-1,3-benzenediamine) dihydrochloride} in the presence of the various cations and anions without the using of any masking agents, but tartrate and citrate ions were interfered. The ligand of Bismark Brown R and complexes of Al(III) and Cr(III) were shown the maximum absorbance at the same wavelength together and both metallic ion were interfered to determine each other, but Al(III) were able to determine after oxidation of Cr(III) to Cr(VI).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.1
• /
• pp.18-25
• /
• 1998

G $d_{0.2}$C $e_{0.8}$ $O_{1.9}$(CGO) for electrolyte and L $a_{0.5}$S $r_{0.5}$Mn $O_3$(LSM50) for cathode in Solid Oxide Fuel Cells(SOFC) were synthesized by citrate process. Specimens were prepared with sintering temperatures at 110$0^{\circ}C$, 120$0^{\circ}C$ and 130$0^{\circ}C$, which were fabricated by slurry coating with citric acid contents. Interfacial resistance was measured between cathode and electrolyte using AC-impedance analyzer. With various citric acid content, the degree of agglomeration for the initial particles changed. Also sintering temperature changed the particle size and the degree of densification of cathode. Factors affecting the interfacial resistance were adherent degree of the electrolyte and cathode, distribution of TPB(three phase boundaries, TPB i.e., electrolyte/electrode/gas phase area) and porosity of cathode. By increasing the sintering temperature, particle size and densification of the cathode were increased. And then, TPB area which occurs catalytic reaction was reduced and so interfacial resistance was increased.sed.sed.d.

• Microbiology and Biotechnology Letters
• /
• v.43 no.2
• /
• pp.164-168
• /
• 2015

Citric acid is produced via submerged fermentation using yeasts. Among eight different strains of yeast, Candida zeylanoides was chosen as the strain for producing citric acid and optimized for various C/N ratios and effects of phosphate or Fe²⁺ ions in a clean carbon source medium (glucose: fructose, 1:1). The yield of citric acid was maximized at a C/N ratio of 40/1, a phosphate addition of 1.0 g/l, and an Fe²⁺ ion concentration of less than 50 mg/l, yielding up to 91 g/L in the broth with 18.5 g/l of isocitric acid in a six-day fermentation period using a pre-treated molasses medium. The yield of batch culture was 0.51 (Y_p/s, g/g) in a 5 L-Jar fermenter.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.136-136
• /
• 2017

화학제염 기술은 산화제, 환원제, 금속이온, 무기산등이 혼합되어 있는 화학용액을 사용하여 원전기기 계통 내부에 생성된 고방사능 준위의 산화막과 오염물질을 제거하는 기술이다. 원전의 해체 및 유지보수에 있어 방사능 피복저감을 위한 필수적인 기술이다. 현재 원전 해체 산업은 잠재성이 높은 고부가가치 창출 산업으로 주목을 받고 있다. 원전 보유국의 경우, 기존 상용 제염기술과는 차별성 있는 제염기술을 확보하고자 노력하고 있다. 기존의 공정과 비교하여 공정비용 및 시간을 감소시킬 수 있어야 할 뿐만 아니라, 화학용액에 의한 원전 계통 금속 부품의 부식 및 손상을 최소화해야 한다. 금속 부품이 화학약품에 의한 부식손상을 받는다면 금속 부품의 수명 및 재활용 가치가 감소하기 때문에, 화학제염 기술 적용에 있어 용액에 대한 재료의 건전성 평가가 사전에 필히 이루어져야 한다. 본 연구에서는 원전 냉각재 펌프용 재료로 주로 사용되는 Stainless 304강을 시험편으로 선정하여, 화학제염 시험공정 3가지에 대한 부식손상 특성을 규명하였다. 산화공정은 과망간산($HMnO_4$) 용액을 공통으로 사용하였으며, 산화공정 종료 후 환원공정은 각 시험공정에 따라 시험공정 1은 옥살산($H_2C_2O_4$) 2000ppm, 시험공정 2는 옥살산($H_2C_2O_4$)1500ppm + 시트르산($H_8C_6O_7$)500ppm, 그리고 시험공정 3은 옥살산($H_2C_2O_4$) 3000ppm 용액을 각각 투입하여 수행하였다. 산화, 환원공정을 1Cycle로 하여, 각 시험공정 별로 총 5Cycle을 실시하였다. 각 시험공정 Cycle종료 후 시험편을 취외하여 무게감량측정, SEM(Scanning electron microscope) 분석, 3D현미경분석 그리고 타펠분극 실험을 실시하였다. 각 분석결과를 토대로 하여, Stainless 304강에 대한 화학제염 시 모델별 시험공정에 따른 부식특성을 규명하였다.

• Korean Journal of Food Science and Technology
• /
• v.22 no.3
• /
• pp.319-324
• /
• 1990

The effects of pH, protein and fat content, addition of emulsifiers, stabilizer, sugar, salt and calcium salt on the stability of soymilk suspension were investigated by analyzing the cream separated and precipitates of soymilk which is prepared by various conditions. In the alkaline region of pH, soymilk showed a good stability of the suspension and particularly, above pH 10, precipitates were not formed. When 1.5% of palm oil with 0.4% of glycerine monostearate was added to soymilk in the hydrophile-lipophile balance (HLB) value of 4 to 7, resulted maximal emulsion stability occured below H LB 6. The stability was decreased with increasing the fat concentration and soy oil showed better emulsion stability than that of palm oil. Among the commercial stabilizers, 0.03% of carrageenan was most effective. The stability was not decreased by addition of sugar up to 3% while it was decreased by addition of sodium salt and calcium salt at low level.

• Journal of the Korean Geosynthetics Society
• /
• v.12 no.1
• /
• pp.29-38
• /
• 2013

This paper presents the analysis condition of remediation technique of contaminated fine-grained soil and physical properties of bio-degradable drain for analysis site applicability using bio-degradable drain method. As the result, two kinds of developed degradable drains (cylindricality shaped and harmonica shaped) are satisfied the Korean Industrial Standard. And the cylindricality shaped drain has an excellent discharge capacity than that of another one. By the results of laboratory test, the citric acid is chosen as the washing agent because it has low toxicity, so it is able to minimize harmful influence to environment. Furthermore the subject contaminants were selected as Cd, Cu and Pb. Based on the field pilot test results, the most remedial efficiency is the use of reactive material applied in bio-degradable drain method with the process of injecting the washing agent and extraction of contaminated fluid.

• Korean Chemical Engineering Research
• /
• v.46 no.5
• /
• pp.868-874
• /
• 2008

The Ni based adsorbent was prepared by co-precipitation method and its performance for removing carbon monoxide was investigated. Here, silica, aluminium silicate and ${\gamma}$-alumina were used for carriers of catalyst. $Ni(NO_3)_2{\cdot}6H_2O$ and $Ni(CH_3COO)_2{\cdot}4H_2O$ were utilized for Ni precursors. Precipitants were urea and citric acid. After precipitation of Ni salt on the carrier and following reduction using $H_2$ gas, adsorbent was prepared and its performance was analyzed based on EDS, TPR and XRD experiments. In accordance with change of precipitation agents, Ni salts on carrier, carriers and reduction condition. Adsorbent performance for removing carbon monoxide was investigated. The adsorbent with 54.8 wt% Ni prepared using urea precipitant under reduction condition at $500^{\circ}C$ for 3 h exhibited the best CO removal performance.

• Journal of the Korean Chemical Society
• /
• v.48 no.6
• /
• pp.583-589
• /
• 2004

In a stream of aqueous sample, trace arsenic ions were quantitatively coprecipitated and detected in ICP-AES through hydride generation. In was used as a coprecipitating reagent. The precipitate was collected on a filter and dissolved by HCl. The eluted As was sent into the reaction coil to generate hydrides and analyzed by ICP. With optimal conditions, and with a sample of 0.3 mL, an enrichment of 70 was obtained with the sampling speed of 10/hr. When compared with coprecipitation and hydride generation technique, the sensitivity was increased by 7 and 10 times, respectively. The limit of detection limit$(3{\sigma})$ was 0.020 ${\mu}g\;L^{-1}$ and the precision was 7-10%. Separation of $As^{3+}\;and\;As^{5+}$ were possible using citric acid in hydride generation.

• Korean Journal of Food Science and Technology
• /
• v.13 no.4
• /
• pp.307-313
• /
• 1981

The components of several kinds of Sokokju (old Korean cleared rice wine) prerared in the laboratory by two steps mashing and commercial Yakju (Korean cleared rice wine) were evaluated. The Sokokju mashed with half steamed waxy rice in tile primary fermentation yielded higher contents of alcobol and extract. Especially considerable amount of pyruvate was contained in it. The commercial Yakju sample contained abundantly tartarate and citrate while dominant organic acids in the fermented mashes of Sokokju were lactate, fumarate and succinate. The taste characteristics of the Sokokju brewed with half steamed waxy rice were most acceptable to the sensory panel.