• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3691-3695
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• 2012

Photocatalytic reduction of hexavalent chromium (Cr(VI)) in ferric-tartrate system under irradiation of visible light was investigated. Effects of light resources, initial pH value and initial concentration of various reactants on Cr(VI) photocatalytic reduction were studied. Photoreaction kinetics was discussed and a possible photochemical pathway was proposed. The results indicate that Fe(III)-tartrate system is able to rapidly and effectively photocatalytically reduce Cr(VI) utilizing visible light. Initial pH variations resulte in the concentration changes of Fe(III)-tartrate complex in this system, and pH at 3.0 is optimal for Cr(VI) photocatalytic reduction. Efficiency of Cr(VI) photocatalytic reduction increases with increasing initial concentrations of Cr(VI), Fe(III) and tartrate. Kinetics analysis indicates that initial Fe(III) concentration affects Cr(VI) photoreduction most significantly.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.1273-1274
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1569-1570
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• 2013

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.116-124
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• 2019

The rapid development of the poultry industry has led to the production of large amounts of manure, which produce substances like hydrogen sulfide ($H_2S$) that contribute to odor pollution. $H_2S$ is a highly undesirable gas component and its removal from the environment is therefore necessary. Sulfur-oxidizing bacteria (SOB) are widely known to remove contaminating $H_2S$ due to their ability to oxidize reduced sulfur compounds. In this study, three potential SOB (designated AH18, AH25, and AH28) that were previously isolated from a hot spring in Malaysia were identified by 16S rRNA gene analysis. Laboratory-scale biological deodorization experiments were conducted to test the performance of the three isolates-in the form of pure or mixed cultures, with the cells immobilized onto alginate as a carrier-in reducing the $H_2S$ from chicken manure. On the basis of 16S rRNA phylogenetic analysis, isolate AH18 was identified as Pseudomonas sp., whereas isolates AH25 and AH28 were identified as Achromobacter sp. The most active deodorizing isolate was AH18, with an $H_2S$ reduction rate of 74.7% (p < 0.05). Meanwhile, the reduction rates for isolates AH25 and AH28 were 54.2% and 60.8% (p > 0.05), respectively. However, the $H_2S$ removal performance was enhanced in the mixed culture, with a reduction rate of 81.9% (p < 0.05). In conclusion, the three potential SOB isolates were capable of reducing the $H_2S$ from chicken manure in the form of a pure culture immobilized on alginate, and the reduction performance was enhanced in the mixed culture.

• 대한화학회지
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• 제33권5호
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• pp.484-495
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• 1989

질소, 산소 주게원자를 가진 리간드(EDTA, DTPA, IDA, CyDTA, OX)와 몰리브덴(V) 착물$[Et_4N)_2[MoOCl_5]$을 반응시켜 이량체 몰리브덴(V)을 합성하였다. 합성한 몰리브덴(V) 착물은 원소분석, 적외선 스펙트럼, 양성자 자기 공명 스펙트럼, 전자흡수 스펙트럼에 의해 구조를 밝혔다. 전기화학적인 환원메카니즘을 추정하기 위하여 pH $3.571∼10.725$인 $CH_3COOH/NaOOCCH_3 Na_2B_4O_7/H_3BO_3,\;NaH_2PO_4/NaOH,\;NaH_2PO_4/Na_2HPO_4, \;NH_3/NH_4Cl$ 완충용액에서 순환전압전류법, 일정전위전기량법, 분광광도법을 이용하였다. Mo-EDTA, DTPA, IDA, CyDTA 착물의 순환전압전류그램에서는 pH가 낮을 때(약 6.00 이하) 두개의 환원파가 나타났으며 제 1환원파에 관련된 전자수는 두개이고 제 2환원파에 관련된 전자수도 두개이다. pH가 높을 때(약 8.00 이상)는 한개의 환원파가 나타났으며 관련된 전자수는 네개이었다. Mo-OX, 착물의 순환전압전류그램은 pH가 약 7.2 이하에서만 얻을 수 있었고 한개의 파가 나타났으며 관련된 전자수는 네개이다.

• Environmental Engineering Research
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• 제10권4호
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• pp.174-180
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• 2005

Nano-sized iron was synthesized using borohydride reduction of $Fe^{3+}$ in aqueous solution. A wide range of synthesis conditions including varying concentrations of reagents, reagent feeding rate, and solution pH was applied in an aqueous system under anaerobic condition. The reactivity of nano-sized iron from each synthesis was evaluated by reacting the iron with TCE in batch systems. Evidence obtained from this study suggest the reactivity of iron is strongly dependent on the synthesis solution pH. The iron reactivity increased as solution pH decreased. More rapid TCE reduction was observed for iron samples synthesized from higher initial $Fe^{3+}$ concentration, which resulted in lower solution pH during the synthesis reaction. Faster feeding of $BH_4^-$ solution to the $Fe^{3+}$ solution resulted in lower synthesis solution pH and the resultant iron samples gave higher TCE reduction rate. Lowering the pH of the solution after completion of the synthesis reaction significantly increased reactivity of iron. It is presumed that the increase in the reactivity of iron synthesized at lower pH is due to less precipitation of iron (hydr)oxides or less surface passivation of iron.

• 한국염색가공학회지
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• 제11권4호
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• pp.24-30
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• 1999

Cotton fabric was dyed with indigo at different pHs, dye concentrations, and repeated dyeings. And the K/S value and dye uptake of the dyed materials at those conditions were determined. The decrease of pH during the reduction process of indigo stock solution was observed. As a result the decrease of pH of the dye stock solution depended on the dye concentration and initial pH. The highest K/S value was shown at fabric dyed at pH 11 and the relationship between K/S value and dye uptake depended on initial pH of reduction bath and the slope was lower as the pH increased to 13.

• 한국소음진동공학회논문집
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• 제23권9호
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• pp.823-830
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• 2013

The purpose of this study is to develop a noise reduction device installed at the top of noise barrier for further decreasing of noise level of 400 km/h class high-speed railroad. For this, the frequency spectrum of 400 km/h class high-speed railroad was analyzed through the field noise test, and the tuning frequency was determined to design a noise reduction device. The noise reduction device was designed to have noise reduction performance of at least 3 dB(A) using the prediction method(2D BEM) and through the laboratory test with the prototype. Finally, the outdoor test showed that this device could decrease noise level of 400 km/h class high-speed railroad even more than 3 dB(A).

• Journal of Microbiology and Biotechnology
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• 제19권7호
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• pp.698-708
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• 2009

High rate sulfate reduction under acidic conditions opens possibilities for new process flow sheets that allow the selective recovery of metals from mining and metallurgical waste and process water. However, knowledge about high-rate sulfate reduction under acidic conditions is limited. This paper investigates sulfate reduction in a membrane bioreactor at a controlled pH of 5. Sulfate and formate were dosed using a pH-auxostat system while formate was converted into hydrogen, which was used for sulfate reduction. Sulfide was removed from the gas phase to prevent sulfide inhibition. This study shows a high-rate sulfate-reducing bioreactor system for the frrst time at pH 5, with a volumetric activity of 188 mmol $SO_4^{2-}$/I/d and a specific activity of 81 mmol $SO_4^{2-}$volatile suspended solids/d. The microbial community at the end of the reactor run consisted of a diverse mixed population including sulfate-reducing bacteria.

• 방송공학회논문지
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• 제14권4호
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• pp.501-508
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• 2009

본 논문은 H.264 동영상 부호기를 위한 효율적인 주파수 영역 잡음 제거 기법을 제안한다. 각 변환 블록과 잡음 제거를 위해 변형된 곱셈 팩터 행렬를 내적하는 방식으로 Wiener filtering이 이루어진다. 구현 시 look-up table을 이용하면 제안한 방법에서의 곱셈 연산을 간단히 대신할 수 있기 때문에 필터링에 의한 연산량은 무시할 만하다. 또한, 실험 결과를 통해 제안한 방법이 H.264 부호기에서 두드러진 잡음 제거 성능을 보임을 알 수 있다.