• 태양에너지
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• 제20권1호
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• pp.11-20
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• 2000

To get more insight into the buffering effects of the p-${\mu}c$-Si:H Inserted at the p-a-SiC:H/i-a-Si:H interface, we present a systematic numerical simulation using Gummel-Schafetter method. The reduced recombination loss at the p/i interface due to a constant bandgap buffer is analysed in terms of the variation of the p/i Interface region with a short lifetime and the characterisitics of the buffer such as mobility bandgap, acceptor concentration, and D-state density. The numerical modeling on the constant bandgap buffer demonstrates clearly that the buffering effects of the thin p-${\mu}c$-Si:H originate from the shrinkage of highly defective region with a short lifetime in the vicinity of the p/i interface.

• Journal of Microbiology and Biotechnology
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• 제18권6호
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• pp.1130-1135
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• 2008

The effect of pH on anaerobic hydrogen production was investigated under various pH conditions ranging from pH 3 to 10. When the modified Gompertz equation was applied to the statistical analysis of the experimental data, the hydrogen production potential and specific hydrogen production rate at pH 5 were 1,182 ml and 112.5 ml/g biomass-h, respectively. In this experiment, the maximum theoretical hydrogen conversion ratio was 22.56%. The Haldane equation model was used to find the optimum pH for hydrogen production and the maximum specific hydrogen production rate. The optimum pH predicted by this model is 5.5 and the maximum specific hydrogen production rate is 119.6 ml/g VSS-h. These data fit well with the experimented data($r^2=0.98$).

• 공업화학
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• 제9권1호
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• pp.33-37
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• 1998

새로운 미세공구조를 갖는 제올라이트성 물질인 ETS-4와 ETS-10의 합성에 pH가 미치는 영향을 조사한 결과, pH가 10.4인 경우 세공의 크기가 약 $8{\AA}$인 ETS-10가 합성되는 반면 pH가 증가하면서 두 종류가 동시에 합성되는 것을 알 수 있었다. 그러나 pH가 11.5인 경우에는 순수한 ETS-4만이 합성되는 것을 알 수 있었다. Morphology를 보면 ETS-10의 경우 정점이 잘린 두 개의 피라미드를 겹쳐놓은 형상에서 pH가 증가함에 따라 순수한 ETS-4의 경우 판상형의 결정체들이 형성되는 것을 알 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제16권8호
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• pp.1218-1223
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• 2003

The effects of type (high and low voltages) and time (3, 40 and 60 min postmortem) of stimulation on drip loss and meat color at 24 h post-mortem were determined on M. longissimus dorsi of 38 crossbred steers and heifers. In addition, the effect of pH early postmortem (70 min postmortem) on the rate and extend of meat tenderization was examined. Either high or low voltage stimulation at 3 min showed a tendency for faster pH decline (p=0.052) and higher drip loss (p=0.08), and improved the color dimensions of L*, a* and b* (p<0.01), compared to stimulation at 40 min. This was equivalent to approximately one unit of an AUSMEAT color chip. On the other hand, although there were significant differences in pH decline between high voltage stimulation at 40 and 60 min, and between low voltage stimulation at 40 min and control sides, drip loss and meat color did not differ significantly (p>0.05). The results suggested that early application of stimulation, regardless of type of stimulation, improved overall meat color at 24 h postmortem through its effect on faster glycolysing rate. However, if the pH decline was moderate, the benefit of electrical stimulation on meat color was not apparent. An intermediate pH decline resulted in the lowest shear force. Due to differential ageing rates the optimum pH at 70 min postmortem increased with ageing time from 5.96, 6.07, 6.12 and 6.14 for 1, 3, 7 and 14 days postmortem, respectively. This implied that a small difference in the rate of pH decline was important, especially carcasses stimulated for very early postmortem, and the optimum rate of pH decline varied with intended ageing period. The study suggests that the beneficial or adverse effects of electrical stimulation on drip loss, meat color and tenderness is determined by the rate of pH decline, rather than by stimulation treatment and time of application per se.

• 한국식품과학회지
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• 제20권3호
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• pp.453-458
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• 1988

식품의 가공, 저장 및 조리중 있어서 Maillard 반응으로 용이 하게 생성되는 Maillard 반응생성물과 비투석성 melanoidin의 아질산염 소거작용에 관하여 검토하였는데 그 결과를 요약하면 다음과 같다. 1. Maillard 반응생성물과 비투석성 melanoidin의 아질산염 소거능은 우수한 것으로 나타났다. 2. 반응용액의 pH변화에 따른 아질산염 소거능은 pH1.2에서 가장 켰으며 pH가 증가 할수록 아질산염 소거능은 감소하였다. 3. 환원능을 소실시키고 난 후의 아질산염 소거능은 pH1.2에서 1/2이하로 감소하였다. 4. Maillard반응생성물이 나타내는 아질산염 소거작용에는 melanoidin이 크게 관여하는 것으로 나타났다.

• 한국식품과학회지
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• 제31권2호
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• pp.399-403
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• 1999

가열, pH, 그리고 유기산 및 몇가지 염들의 첨가가 마쇄 마늘의 저장 중 일어나는 변색에 미치는 영향에 대하여 조사하였다. 그 결과 식초산, 구연산, 젖산은 녹변을 촉진시켰으나 소금은 영향이 거의 없었다. 마쇄마늘의 pH를 4.0으로 감소시켰을 때 녹변은 현저히 감소되었지만 그 이상의 산성 pH에서는 녹변이 오히려 증가되었다. 첨가한 인산염 중 $Na_{2}HPO_{4}$와 $Na_{3}PO_{4}$는 약간의 녹변억제 효과가 있었으며, BHA나 BHT등 항산화제는 효과가 없었다. 마쇄 마늘을 $80^{\circ}C$에서 10분간 pH $3.0{\sim}5.0$ 범위에서 가열했을 때 $80^{\circ}C$에서는 a값이 (-)값 이하로 더 감소하여 녹변이 심해졌으나 $90^{\circ}C$와 $100^{\circ}C$에서 30분 이상 가열했을 때 (-)a값이 낮아져 녹변이 억제되었다.

• 한국토양비료학회지
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• 제14권1호
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• pp.17-23
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• 1981

요소(尿素)와 병용(倂用)된 염화가리나 황산가리(黃酸加里)가 담수(湛水) 치원조건하(置元條件下)에서 암모니아의 휘산(揮散)에 주는 영향(影響)을 밝히기 위(爲)하여 pH가 낮은 (4.85) 산성식질답토양(酸性埴質畓土壤)과 pH가 높은(6.70) 간척지사질식양토(干拓地砂質埴壤土)를 공시(供試)하여 질내(窒內)에서 시험(試驗)한 결과(結果)는 다음과 같다. 1. 산성토양(酸性土壤)에 사용(使用)한 가리(加里)는 pH를 높이고 암모니아의 휘산(揮散)을 증가(增加)하였다. 2. pH가 높은 간척지염류토양에서는 가리(加里)의 시용(施用)으로 pH를 낮추고 암모니아의 휘산(揮散)을 줄이는데 그 효과는 황산가리(黃酸加里)가 염화가리보다 컸다. 3. 황산가리(黃酸加里)보다 염화가리를 시용(施用)한 토양(土壤)에서 암모니아의 휘산(揮散)이 많은 것 같다. 그러나 pH가 높은 간척지토양(干拓地土壤)에서는 염화가리의 이 효과가 높은 염농도에 덮여 버리는 것 같다. 4. 요소(尿素)는 토양(土壤)의 pH를 크게 높였다. 산성(酸性) 토양(土壤)에서는 황산가리(黃酸加里)가 염화가리보다 토양(土壤)의 pH를 더 높였으나 원래(原來)의 pH가 높은 간척지토양(干拓地土壤)에서는 반대(反對)로 황산가리(黃酸加里)가 염화가리보다 pH를 낮추었다. $SO_4$의 환원(還元)에 기인(基因)하는 것으로 생각된다.

• 상하수도학회지
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• 제24권5호
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• pp.581-593
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• 2010

The objectives of this study were to investigate the effects of raw water pH and basicity of coagulants on turbidity removal with several raw waters having different level of turbidity, alkalinity and pH. Raw waters were sampled from M, S and B water treatment plants(WTP) located at Miryang, Nakdong, Han river, respectively. Six coagulants which have different levels of basicity and aluminum contents were used for this evaluation. High basicity of the coagulant helped to properly control coagulation processes for treating turbid and low alkali raw water. It was difficult for operators to determine optimum coagulant dose for high basicity coagulants, since residual turbidity tended to decrease continuously as coagulant dose increased. Turbidity removal efficiencies with high basicity coagulants(E and F) were higher than the other coagulants at ambient pH for the M WTP. Turbidity removal efficiencies, however, at adjusted pH 7.0 showed similar among six coagulants. Residual turbidity kept low at excess dosages with high basicity coagulants. Optimum coagulant dosages at adjusted pH 7.0 showed higher than those at ambient pH in M WTP. On the contrary in B WTP, optimum coagulant dosage at ambient pH were higher than that at adjusted pH 7.0.

• Animal cells and systems
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• 제7권4호
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• pp.345-348
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• 2003

The effects of acute acid stress on hatching success and hatching period of laboratory-reared hermaphroditic fish Rivulus marmoratus were examined. The effects of acute acid toxicity on mortality was also determined in three life stages of this fish. There was a significant negative effect of acid stress on hatching performance in the R. marmoratus embryos. The hatching success was only 5% at pH 3.5 compared to over 78% at pH higher than 4.0. The hatching period was also delayed by low pH treatments. The larval and juvenile stages were more sensitive to acid toxicity on mortality than the adult stage, but larvae and juveniles showed similar sensitivity. The 96-h LC50 value was pH 3.8 in larval and juvenile stages and pH 3.3 in adult stage.

• Journal of the Korean Wood Science and Technology
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• 제51권1호
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• pp.38-48
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• 2023

Two important steps in utilizing technical kraft lignin (KL) from black liquor to synthesize lignin-phenol-formaldehyde (LPF) resin are its extraction via precipitation and fractionation. However, the effects of precipitation pH and acetone fractionation on the characteristics of hardwood KL have not been studied for LPF resins. Therefore, this paper reports the effects of the precipitation pH of black liquor and acetone fractionation on the characteristics of KL from mixed hardwood species for LPF resins. The precipitation was conducted at various pH levels from 3 to 9 of black liquor to obtain crude KL (C-KL), which was used in acetone fractionation to produce acetone-soluble KL (AS-KL) and acetone-insoluble KL (AI-KL). Precipitation at pH 3 and 9 produced the highest and lowest yields of C-KL, respectively. As expected, the C-KL infrared spectra were similar regardless of the precipitation pH levels. As the pH increased, the molecular weight of C-KL increased. However, the molecular weight of AS-KL and AI-KL after acetone fractionation increased to a maximum of 4,170 and 47,190 g/mol at pH 7, then decreased to 3,210 and 19,970 g/mol at pH 9, respectively. The smallest molecular weights of AS-KL and AI-KL were 3,210 and 15,480 g/mol and were found at pH 9 and 3, respectively. These results suggest that both AS-KL at pH 9 and AI-KL at pH 3 have good potential as starting lignins for synthesizing LPF resins that require cross-linking for polymerization.