• 한국미생물·생명공학회지
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• 제47권2호
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• pp.296-302
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• 2019

In this study, the effects of ammonium concentration ($117.5-1155.0mg-N{\cdot}l^{-1}$), nitrite concentration ($0-50.0mg-N{\cdot}l^{-1}$), and temperature ($15-35^{\circ}C$) on nitrification performance and its functional genes (amoA-arc, amoA-bac, hao) in an enriched consortium inoculated with humic acid were determined. Notably, the maximum nitrification rate value was observed at $315mg-N{\cdot}l^{-1}$ of ammonium, but the highest functional gene copy numbers were obtained at $630mg-N{\cdot}l^{-1}$ of ammonium. No inhibition of the nitrification rate and functional gene copy numbers was observed via the added nitrites. The optimum temperature for maximum nitrification performance was observed to be $30^{\circ}C$. The amoA-bac copy numbers were also greater than those of amoA-arc under all test conditions. Notably, amoA-arc copy numbers and nitrification efficiency showed a positive relationship in network analysis. These results indicate that ammonium-oxidizing archaea and bacteria play important roles in the nitrification process.

• 대한환경공학회지
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• 제33권10호
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• pp.774-781
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• 2011

지르코늄합금 튜브 제조공정은 튜브 산세 시 질산과 불산을 사용하고 있어 세척 시 발생되는 폐수의 주요 오염물질인 질산성질소와 불소성분을 제거하기 위한 폐수처리는, 1차 화학응집처리에 의한 불소성분 제거공정, 황산화탈질반응을 이용한 SOD (Sulfur Oxidation Denitrification)공법에 의한 독립영양탈질공정, 그리고 2차 화학응집처리공정으로 구성되어 있다. 본 연구에서는, 처리공정에서 불소의 농도가 황산화탈질공정(SOD)의 탈질반응에 미치는 영향과 황산화탈질반응을 유지하기 위한 최적 운전조건을 검토하였다. 황산화탈질 반응은 불소농도 20 ppm 이하에서 거의 영향을 주지 않았으며, NaOH로 pH를 조절하는 것보다 NaOH와 $NaHCO_3$를 혼합하여 pH와 알칼리도를 조절해주는 것이 질소제거당량을 높여주는 효과가 있는 것으로 나타났다. 또한, 황산화탈질미생물에 필요한 미량원소와 알칼리성분이 혼합된 미생물활성화제가 알칼리도를 보충해줄 뿐만 아니라 황산화탈질미생물의 성장과 증식에도 영향을 주었으며, 그 결과 무기계 산업폐수처리 시 필요한 주기적인 미생물 식종 없이 운전이 가능한 결과를 얻었다. 이상의 결과를 통해, 황산화탈질공법(SOD공법)이 산업폐수의 질산성질소제거에 매우 유용한 공법임이 확인되었으며, 미생물활성화제가 황산화탈질미생물의 활성화에 기여함이 밝혀졌다.

• 한국식품저장유통학회지
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• 제9권2호
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• pp.154-160
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• 2002

박피 토란의 저장성을 향상시키기 위한 방안으로 전해산화수, 유자과즙을 첨가한 전해산화수 및 명반수를 사용하여 제조한 침지저장액에 따른 저장 효과를 살펴본 결과, 토란 수분함량은 80.05%에서 저장 25일째 수분의 흡수로 인해 82.12~84.24%로 다소 증가하였으나 처리구간의 차이는 거의 없었다. 색도는 전반적으로 L값은 감소하였으며 a, b값이 증가되는 현상을 보여주었으며, 조직감은 모든 처리구에서 초기 4,520$\pm$75 g에서 점차로 감소하는 경향을 보였으나 그 감소 폭이 유자과즙첨가구가 가장 적은 것으로 나타나 저장 25일째 4,160$\pm$80 g의 수준을 보였다. 총 vitamin C함량은 0.5%유자과즙 첨가 구에서 25일째 6.99 mg%로 약 57%의 보존율을 보여 가장 손실이 적었다. 총당은 대부분의 처리구에서 저장 15일째까지 급격히 하강하다가 저장 15일 이후에는 감소속도가 완만한 것을 볼 수 있었으며, 저장 중의 유리당의 함량은 저장기간에 따른 증감의 큰 변화 폭은 관찰할 수 없었다. 단지 sucrose 함량은 저장 중반기인 10일 전후에 일부 감소하다가 다시 증가하여 저장 25일째에는 처리구에 관계없이 저장 초기 값의 1.5~2배 수준에 도달하였으며, fructose, glucose, maltose는 저장기간별 처리구간에 따른 유의적인 차이가 나타나지 않았다. 박피 토란의 주 아미노산은 aspartic acid와glutamic acid로 각각 1,084.8 mg/100g. 691.8 mg/100g으로 나타났으며, 전해산화수에 침지하여 저장한 경우 aspartic acid 함량이 초기보다 13.9% 수준 증가하였다. 한편, 필수아미노산총량은 유자과즙 첨가구에 저장한 경우가 총당 감소율 측면에서 가장 유리한 것으로 나타났다.

• 미생물학회지
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• 제29권4호
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• pp.250-257
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• 1991

An obligate methanol-oxidizing bacterium, Methylobacillus sp. strain SK1, which grows only on methanol was isolated from soil. The isolate was nonmotile Gram-negtive rod. It does not have internal membrane system. The colonies were small, whitish-yellow, and smooth. The guanine plus cytosine content of the DNA was 48 mol%. Cellular fatty acids consisted predominantly of large amounts of straight-chain saturated $C_{16:0}$ acid and unsaturated $C_{16:1}$ acid. The major ubiquinone was Q-8, and Q-10 was present as minor component. The cell was obligately aerobic and exhibited catalase, but no oxidase, activity. Poly-.betha.-hydroxybutyrate, endospores, or cysts were not observed. the isolate could grow only on methanol in mineral medium. Growth factors were not required. The isolate was unable to use methane, formaldehyde, formate, methylamine, and several other organic compounds tested as a sole source of carbon and energy. Growth was optimal at 35.deg.C and pH 7.5. It could not grow at 42.deg.C. The doubling time was 1.2h at 30.deg.C when grown with 1.0%(v/v) methanol. The growth was not affected by antibiotics inhibiting cell wall synthesis and carbon monoxide but was completely suppressed by those inhibiting protein synthesis. Methanol was found to be assimilated through the ribulose monophosphate pathway. Cytochromes of b-, c-, and o- types were found. Cell-free extracts contained a phenazine methosulfate-linked methanol dehydrogenase activity, which required ammonium ions as an activator. Cells harvested after the late exponential phase seemed to contain blue protein.ein.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.272-277
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• 2004

The primary aim of this study is to investigate new semi-abrasive free slurry including acid colloidal silica and hydrogen peroxide for copper chemical-mechanical planarization (CMP). In general, slurry for copper CMP consists of colloidal silica as an abrasive, organic acid as a complex-forming agent, hydrogen peroxide as an oxidizing agent, a film forming agent, a pH control agent and several additives. We developed new semi-abrasive free slurry (SAFS) including below 0.5％ acid colloidal silica. We evaluated additives as stabilizers for hydrogen peroxide as well as accelerators in tantalum nitride CMP process. We also estimated dispersion stability and Zeta potential of the acid colloidal silica with additives. The extent of enhancement in tantalum nitride CMP was verified through anelectrochemical test. This approach may be useful for the application of single and first step copper CMP slurry with one package system.

• 약학회지
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• 제31권4호
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• pp.197-203
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• 1987

When pyrazinamide is used in the treatment of tuberculosis, the measurement of pyrazinoic acid which is an intermediate metabolite of pyrazinamide in body is required in order to prevent its associated side-effects, especially that of hyperuricemia. Effects of vitamin B$_6$ on pyrazinoic acid metabolism were studied in this experiment. The activity of hepatic pyrazinoic acid oxidizing enzyme in the presence of pyridoxal was powerfully inhibited, and the pattern was competitive inhibition type. Whereas, its enzyme activity was significantly increased by the treatment of pyridoxal, and the characteristics of the increase may include induction of enzyme proteins. As mice received pyrazinoic acid(300mg/kg) after pyridoxal-pretreatment(40mg/kg) once daily for 4 days, the blood level of pyrazinoic acid and uric acid was decreased significantly.

• 공업화학
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• 제10권2호
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• pp.218-224
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• 1999

원자로 정지시 혼상 탈염기의 최적 운전방법을 제안할 목적으로 산성-산화성 분위기에서 저농도의 Ni, Co 및 Ag 이온이 함유된 모의 냉각재 용액의 연속식 이온교환특성을 연구하였다. 금속 이온의 제거 용량에 미치는 양이온 교환수지 형태의 효과로서 $H^+$형 수지의 성능은 $Li^+$형 수지의 성능보다 약 6% 정도 높은 것으로 나타났다. 혼합층 이온교환 방법인 양이온과 음이온 수지의 혼합은 비혼합시와 비교하여 금속 이온들의 제거 용량에는 영향을 미치지 않았으나 금속 이온들의 파과곡선의 기울기를 매우 조금 증가시켰다. 냉각재의 산성-산화성 분위기와 관계된 영향으로서 붕산의 첨가는 금속 이온들의 파과곡선의 기울기를 매우 작게 감소시킨 반면, 과산화수소의 첨가는 금속이온들의 제거 용량을 약간 감소시켰다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.73-76
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• 2006

Sewage facilities mainly consisted of concrete structures are being deteriorated seriously by biodeterioration originated from sulfur-oxidizing bacteria. To prevent biochemical corrosion of the sewage concrete, antibiotics which prevent growth of sulfur-oxidizing bacteria were developed. Recently, to evaluate biochemical corrosion properties of concrete, antimicrobial performance and resistance to sulfuric acid were investigated respectively. But, in this study, to evaluate it complexly, concrete specimen covered with antibiotics were exposed in the actual sewage environment and were investigated about corrosion properties after three months. As a result, weight change ratio, nature potential and sulfuric ratio of concrete covered with antibiotics were less than plain concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.69-72
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• 2006

Recently sewage facilities mainly consisted of concrete structures are being deteriorated seriously by biodeterioration originated from sulfur-oxidizing bacteria. To prevent biochemical corrosion of the sewage concrete, antibiotics which prevent growth of sulfur-oxidizing bacteria were developed. Existing methods to evaluate properties of biochemical corrosion of concrete examine the antimicrobial performance and resistance to sulfuric acid separately, but don't complexly. So, in this study, new method to test properties of biochemical corrosion of concrete complexly is suggested.

• Advances in materials Research
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• 제13권2호
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• pp.141-151
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• 2024

The aim of this work was to determine the behavior of alloy elements and compounds formed during solidification in the manufacturing process of the CuAgZrCr alloy under an oxidizing environment. Bulk and surface analysis techniques, such as Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Raman and X-ray diffraction (XRD) were used to characterize the phases obtained in the solidification process. In order to focus the analysis on the on grain boundary interface, partial removal of the matrix phase by acid attack was performed. The compositional differences obtained by SEM-EDX, Raman and XPS on post-manufacturing materials allowed us to conclude that the composition of grain boundaries of the alloy is directly influenced by the oxidizing environment of alloy manufacturing.