• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.3
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• pp.490-495
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• 1994

Acid phosphatase (EC3.1.3.2) from carrots was partially purified by ammonium sulfate fractionation (30%-80%), Sephacryl S-200 gel filtration, cm-Sepharose CL-6B and DEAE -Sephacel ion exchange chromatography. The optimum ph and temperature of acid phosphatase from carrots were pH 5.5 and 55$^{\circ}C$, respectively. The enzyme was most stable at ph 6.0 and relatively unstable below pH 4.0 . The activation energy of the enayme was determined to be 10.6kcal/mole. The enzyme utilized p-nitrophenyl phosphate as a substrate among tested possible substrates, whereas it hydrolyzed 5' -IMP and 5'-GMP poorly. The Michaelis -Menten constant(Km) of the enzyme with p-nitrophenyl phosphate as a substrate was identified as 0.55mM. Amongtested metal ions and inhibitors, Al+++ Zn++, Cu++ , fluoride, metavanadate and molybdate ions inhibited the enzyme activity drastically.

• Biomedical Science Letters
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• v.10 no.4
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• pp.347-351
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• 2004

Maggot fibrolase (MsMg-1) was purified from the maggots of Mimela splendems using ammonium sulfate fractionation, DEAE Affi-gel affinity chromatography. This protease had a molecular weight of 85 kDa as determined by SDS-polyacrylarnide gel electrophoresis under reducing conditions. It showed strong proteolytic and fibrinolytic activities. The purified enzyme was strongly inhibited by phenylmethanesulfonyl fluoride, Mn/sup 2+/, and Zn/sup 2+/ but it was not by EDTA, EGT, Mg/sup 2+/, Ca/sup 2+/, and Li/sup 2+/ ions. In these experimental results, we have speculated that MsMg-1 is a serine protease with a strong fibrinolytic activity.

• Journal of Microbiology and Biotechnology
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• v.3 no.3
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• pp.188-193
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• 1993

Superoxide dismutase (SOD) was purified from Pseudomonas polycolor to an electrophoretically homogeneous state and partially characterized. SOD was purified by ammonium sulfate fractionation, column chromatography on DEAE-Sephadex A-50, phenyl-Toyopearl 650 M, and gel filtration on Sephadex G-100. The molecular weight and subunit molecular weight of the purified enzyme were estimated to be 40, 000 and 20, 000, respectively. The purified enzyme remained stable at pH 9.0~11.0, $25^{\circ}C$ for 40 hr, but rapidly became inactive below 9.0. SOD was stable up to $45^{\circ}C$ at pH 9.0 with about 80% relative activity, but rapidly became inactive at temperature above that. The enzyme was insensitive to cyanide and fluoride, and sensitive to hydrogen peroxide and azide. The results suggest that the enzyme be an iron-containing SOD.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.101-109
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• 2016

The purpose of this research was to develop a flat panel display device's glass etchant which can replace hydrofluoric acid. The glass etchant was composed of 18~19% wt% of ammonium hydrogen fluoride, 24~25 wt% of sulfuric acid, 45~46 wt% of water, 4~5 wt% of sulfate and 7~8 wt% of fluoro-silicate. By replenishing the etchant which has the amount of 5% of initial solution's mass, it was possible to reuse the etchant continuously. The developed etchant showed $5{\mu}m/min$ of etching rate at $30^{\circ}C$. The reusable etchant, with replenishing 5% of initial etchant mass showed the stable etching rate, which has the deviation of less than $0.1{\mu}m/min$ etching rate. The glass surface of flat panel display device created from our etching process was in good condition with any defects such as pin hole and dimple.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.794-801
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• 1995

To connect the driver IC and Al coated glass, a method has been developed to plate electrolessly Ni on Al/PR system. It Is necessary to pretreat Al to remove oxide film before plating. In order to find pretreatment process which does not damage photoresist or glass, alkaline and fluoride zincate process have been investigated. Because photoresist and aluminum thin film can easily dissolve in alkaline solution, it is considered that the fluoride zincate process was a suitable one. After immersion in the zincate solution containing 1.5 g/$\ell$ ammonium bifluoride and 100 g/$\ell$ zinc sulfate, electroless nickel plating could be performed. The additive in the zincate solution and thiourea in the plating solution increased smoothness of the plated surface. Acld dip could improve the uniformit of the surface.

• Journal of the Korean institute of surface engineering
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• v.55 no.1
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• pp.24-31
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• 2022

This study investigated the effect of pre-treatment on the PEO film formation of AZ91 Mg alloy. The pre-treatment was conducted for 10 min at room temperature in 0.5 M oxalic acid (C₂H₂O₄) solution containing various ammonium fluoride (NH₄F) concentrations. The pre-treated AZ91 Mg specimens were anodized at 100 mA/cm² of 300 Hz AC for 2 min in 0.1 M NaOH + 0.4 M Na₂SiO₃ solution. When AZ91 Mg alloy was pretreated in 0.5 M oxalic acid with NH₄F concentration less than 0.3 M, continuous dissolution of the AZ91 Mg alloy occurred together with the formation of black smuts and arc initiation time for PEO film formation was very late. It was noticed that corrosion rate of the AZ91 Mg alloy became faster if small amount of NH₄F concentration, 0.1 M, is added. The fast corrosion is attributable to fast formation of porous fluoride together with porous oxides in the reaction products. On the other hand, when AZ91 Mg alloy was pretreated in 0.5 M oxalic acid with sufficient NH₄F more than 0.3 M, a thin and dense protective film was formed on the AZ91 Mg alloy surface which resulted in faster initiation of arcs and formation of PEO film.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.325-331
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• 2007

This study was aimed to find out methods for preventing scale formation from the struvite treated water, and improving ammonium nitrogen removal efficiency in the application of struvite crystallization for ammonium fluoride wastewater wastement. During the struvite mystallization seeding effects varied with G.td value applied as mixing conditions in the experiment. The removal efficiency of ammonium nitrogen$(NH_4^+-N)$ and phosphorus$(PO_4^{3-}-P)$ increased over 90% in the condition of low $G{\cdot}t_d$ value. In the experiment with seeding, $G{\cdot}t_d$ value was shown to decease four times lower than the one without seeding. When adding over 2% seeding materials in the total water volume, ammonium nitrogen removal efficiencies gradually increased, of which observation was also revealed in a paired-sample T-test with 95% reliability.

• Analytical Science and Technology
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• v.29 no.5
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• pp.219-224
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• 2016

불산 중 극미량 음이온의 고상추출과 이온크로마토그래프를 이용한 고감도 분석법이 개발되었다. 불산 중 불소이온이 고상에 의해 제거하였고 이어서 음이온 (F⁻, CH₃COO⁻, Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들이 이온크로마토그래프를 이용하여 연속적으로 분리하였다. 고상 추출법에 영향을 주는 각 인자들 (흡착제의 선택, 시료의 부피 및 pH, 용출 용액과 용출용액의 부피)을 결정하였으며 그 결과 흡착제로서 Oasis WAX 컬럼이 가장 우수하였고 1.0 mL의 시료부피, 용출용액으로 50 mM 초산암모늄염 5 mL가 분리능에서 가장 우수하였다. 개발한 방법에 의한 음이온 (Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들의 방법검출한계는 25 % 불산용액 (w/w) 중에 0.04~0.30 µg/L의 범위를 보였고 정밀도는 20.0와 40.0 µg/L의 농도에서 5 % 이내를 보였다. 한 제조회사에 의한 25 % 불산 중 음이온의 4.2에서 47.5 µg/L의 범위로 모두 검출되었다. 이 방법은 시험절차가 간단하고, 재현성 및 감도가 좋아서 반도체회사에서 불산 중 음이온 불순물을 정도 관리하는데 매우 유용한 방법이 될 것으로 판단된다.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.73-81
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• 2004

To develope of the inexpensive anti-stain chemicals, it was conducted to investigate the inhibitory effectiveness of mycelial growth and anti-mold effectiveness against test fungi causing surface mold of wood, iron corrosivity and hygroscopicity of six fluoride-based chemicals made from industrial by- product.Among the six chemicals. RNF-3 and RNF-4 were the most effective with respect to a mycelial growth control and anti-mold effectiveness. For the wood treatment with these chemicals, the optimum concentration was about 2% and there was no difference in the effectiveness of chemicals between wood species. The wood treated with synthesized chemicals showed a relatively high iron corrosion rate for corrosive F component whereas, in the treatment with RNF-3 and RNF-4, there was no difference from the untreated wood when the concentration was less than 2%. The hygroscopic property of wood was not effected by treatment of these chemicals. To prove the feasibility for practical using of RNF-3 and RNF-4 chemicals, it is necessary to test of anti-mold effectiveness in the sawmill by field test.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.216.1-216.1
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• 2010

본 연구는 최근 하이드레이트와 유사한 형태인 semi-clathrate 형성을 통해 열역학적 촉진제로서 주목받고 있는 TBAF(Tetra-n-butyl ammonium fluoride)의 가스 하이드레이트 형성에 작용하는 영향을 알아보았다. TBAF를 10, 33.8, 45 wt%의 농도로 $CH_4+H_2O$, $CO_2+H_2O$, $N_2+H_2O$계에 첨가하여 가스 하이드레이트 3상 평형점(하이드레이트(H) - 물(Lw) - 기상(V)) 측정을 하였다. TBAF가 첨가된 경우 순수한 $CH_4$, $CO_2$, $N_2$ 가스 하이드레이트보다 평형조건이 더 높은 온도와 더 낮은 압력 영역에서 나타났으며 기체의 종류와 무관하게 TBAF의 농도가 33.8 wt%일 때 10, 45 wt%보다 뛰어난 촉진효과를 갖고 있음을 확인할 수 있었다. 이를 통해 양론비인 TBAF의 농도 33.8 wt% 이상에서는 반응을 하지 않고 남아있는 TBAF가 하이드레이트 생성반응에 방해요소로 작용하는 것을 알 수 있었다. 본 실험에서 얻어진 결과 TBAF를 촉진제로서 사용하는 가스 하이드레이트 공정이라면 33.8 wt% 농도의 사용이 가장 효과적일 것으로 사료된다.