• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2005년도 정기총회 및 제35차 춘계 학술 발표대회
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• pp.297-302
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• 2005

Physicochemical properties were compared between freeze concentrated and vacuum evaporated milk through colour, brix, viscosity, freezing point and pH measurement. Brix and viscosity in each concentrated milk significantly increased due to solute concentration(p<0.05), and there was not much difference between freeze concentrated and evaporative one. Brix results were numerically modeled with the logarithmic regression: Y=-33.460+18.4513 ${\cdot}$ ln(X), $R^2=0.9798$ and this model was fairly fit to predict the solute concentration in the middle of freeze concentration process. Freezing point significantly decreased according to concentration increment(p<0.05) and there was not the significant difference between freeze concentrated and evaporated one. Whereas, in colour and pH value, there were some differences between freeze concentrated and evaporative milk. Vacuum evaporated milk expressed higher discoloration comparing to freeze concentrated one. In pH values, evaporated milk showed the significantly decreased results comparing to freeze concentrated sample, whereas the pH value of freeze concentrated sample expressed the similar value to the reference milk.

• Journal of Microbiology and Biotechnology
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• 제31권3호
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• pp.429-438
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• 2021

Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis.

• 한국표면공학회지
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• 제45권4호
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• pp.162-167
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• 2012

Ni-P/C multi-layer was synthesized by electroless plating and paste coating for better corrosion and surface conductance as a metallic bipolar plate. The Ni-P layer could be synthesized with the range of 2.6~22.4 at.% P contents and it's surface morphology and corrosion resistance depend on content of P. Corrosion resistance of the Ni-P layer in sulfuric acid by electrochemical test is similar with pure Ni. Surface resistance of pure Ni after corrosion was increased about 8% compared to pure Ni. On the other hand, that of the Ni-P/C composite with 20% carbon content was increased only 1%.

• 공업화학
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• 제8권3호
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• pp.502-509
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• 1997

방향족 오염물을 UV산화-고도산화처리기술로 처리할 때, 여러 가지 반응조건에 따른 분해효율에 대해 고찰하였다. 벤젠 50ppm, 에틸벤젠 150ppm, 크실렌 250ppm을 각각 초기농도로하여 UV조사 하에서 시간변화에 따른 분해실험을 행한 결과, 반응 1시간 후 약 95% 이상의 분해율을 나타내었으나, 톨루엔의 경우에는 43%의 분해율을 보였다. 단일성분이 혼합성분에서 보다 분해가 좋았으며, pH변화에서는 벤젠은 pH변화에 관계없이 분해가 잘 되었으며, 에틸벤젠 92%(pH 4.0), 90%(pH 6.4), 91%(pH 10.0), 크실렌 95%(pH 4.0), 90%(pH 6.4), 92%(pH 10.0), 그러나 톨루엔은 80%(pH 4.0), 43%(pH 6.4), 70%(PH 10.0)의 분해율을 나타내었다. 방향족 오염물의 TOC 감소는 에틸벤젠을 제외하고는 유사 1차 반응속도식에 일치하였으며, 이로부터 속도상수를 결정할 수 있었다.

• Nuclear Engineering and Technology
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• 제15권3호
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• pp.179-187
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• 1983

국내원자력 발전소중 고리 1호기 및 5,6호기의 LOCA 사고시 격납용기 살수용액과 썸프 용액의 pH값이 US NRC에서 요구하는 설계기준치를 만족하는가를 알아보기 위해 전산프로그램 “LOCAPH”를 개발하여 최대 pH경우와 최소 pH경우로 나누어 분석하였다. 고리 5,6호기의 경우, 썸프 용액의 pH는 설계기준(최소 8.5이상)을 잘 만족하고 있으며, 살수 용액의 pH는 설계기준(8.5에서 11.0사이)을 약간 벗어나고 있음을 볼 수 있었다. 그러나 고리 1호기의 경우를 보면 썸프 용액의 pH는 역시 설계기준을 잘 만족하고 있으나 살수 용액의 pH는 최대 pH 경우에 있어서 현재 설계에 반영되고 있는 설계기준을 상당히 벗어나고 있음을 알 수 있었다.(고리 1호기 설계시 살수 용액의 pH에 대한 설계 기준치는 없었음) 설계 기준을 만족시키기 위해 고리 1호기의 설계변수를 바꾸어가며 계산해 본 결과 격납용기 살수 용액의 공급원인 핵연료 재장전수 저장탱크(RWST)의 붕소 농도를 2750ppm에서 2850ppm 사이로 유지하거나, 격납용기 살수 용액에 첨가되는 NaOH의 유량을 10gpm에서 24gpm사이로 유지해야 함을 알 수 있었다.

• 한국세라믹학회지
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• 제39권2호
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• pp.194-198
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• 2002

$K_2O{\cdot}CaO{\cdot}P_2O_5$를 기본조성으로 하여 용융법에 의해 유리 형성범위를 정의하고자 하였다. TG-DTA와 DSC를 이용하여 열적 특성을 관찰하고자 하였으며, FT-IR과 Raman Spectroscopy를 이용하여 구조를 분석하였다. $K_2O{\cdot}CaO{\cdot}P_2O_5$의 함량이 증가함에 따라 유리전이온도 및 연화온도는 감소하였다. $K_2O{\cdot}CaO{\cdot}P_2O_5$ 유리의 기본 구조는 이웃한 구조와 상호 결합을 위한 $PO_2$와 $PO_4^{3-}$ 구조와 유리의 골격구조를 이루는 P-O-P 결합이며, CaO의 함량이 증가함에 따라, 유리내의 P-O-P의 결합력은 점차적으로 증가하였으며, $PO_2$와 $PO_4^{3-}$의 intensity는 점차적으로 감소하였다.

• 유기물자원화
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• 제14권1호
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• pp.131-138
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• 2006

본 연구는 혐기성 발효를 이용한 수소생산과정에서 pH를 일정하게 유지한 상태에서 안정적인 수소를 생산하기 위한 최적 pH를 찾고자 하였다. 실험결과 pH 6이었을 때 최적의 조건이었으며 이때 수소생산량은 1175.87 mL/L 이고, 이론적 수소 전환율은 22.51 %였다. pH 5는 901.77 mL/L의 수소가 발생되었으며, 수소 전환율은 17.48 %, pH 7은 454.26 mL/L의 수소생산량과 8.74 %의 수소 전환율을 나타내었다. 그리고 pH 7과 8에서는 각각 452.08 mL/L와 82.25 mL/L의 저조한 수소 생산량을 나타내었다. 자당의 혐기성 발효를 통한 유기산 생성에 있어서 pH가 7과 8에서는 propionate가 주로 관찰되었으나 pH가 5와 6인 영역 에서는 butyrate의 생성이 두드러지는 결과가 나타났다.

• 대한의용생체공학회:의공학회지
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• 제29권1호
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• pp.73-81
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• 2008

The purpose of this study is to observe the brain activity patterns during visual oddball tasks with two difficulty levels by the analysis of high-density event-related potential (ERP). Along with conventional statistical analysis of averaged ERP waveforms, we applied independent component analysis (ICA) for the individual, single-trial analysis and verified its effectiveness. We could identify multiple ERP components such as early visual components (P1, N1), and two components which seem to be important task-related components and showed difficulty-dependent variability (P2, P300). The P2 was found around central region at $180{\sim}220ms$, and the P300 was found globally at $300{\sim}500ms$ poststimulus. As the task became difficult, the P2 amplitude increased, and the P300 amplitude decreased. After single-trial ERPs were decomposed into multiple independent components (ICs), several ICs resulting from P2 and P300 sources were identified. These ICs were projected onto scalp electrodes and the projected ICs were statistically compared according to two task difficulties. For most subjects, the results obtained from single-trial/individual analysis using ICA gave the tendencies of amplitude change that are similar to the averaged ERP analysis for most subjects. The temporal pattern and number of ICs corresponding to ${\mu}$ rhythm was not dependent on the task difficulty. It seems that the motor response was not affected by the task difficulty.

• Environmental Engineering Research
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• 제14권2호
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• pp.134-139
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• 2009

In this study, oxidation of As (III) as well as removal of total arsenic by adsorbents coated with single oxides or multi-oxides (Fe (III), Mn (IV), Al (III)) was investigated. In addition, multi-functional properties of adsorbents coated with multi-oxides were evaluated. Finally, application of activated carbon impregnated with Fe or Mn-oxides on the treatment of As (III) or As (V) was studied. As (V) adsorption results with adsorbents containing Fe and Al shows that adsorbents containing Fe show a greater removal of As (V) at pH 4 than at pH 7. In contrast adsorbents containing Al shows a favorable removal of As (V) at pH 7 than at pH 4. In case of iron sand, it has a negligible adsorption capacity for As (V) although it contains 217.9 g-Fe/kg-adsorbent, Oxidation result shows that manganese coated sand (MCS) has the greatest As (III) oxidation capacity among all metal oxides at pH 4. Oxidation efficiency of As (III) by IMCS (iron and manganese coated sand) was less than that by MCS. However the total removed amount of arsenic by IMCS was greater than that by MCS.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1465-1468
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• 2014

In this study, an intermediate temperature ionic conductor, $Ce_{0.95}Eu_{0.05}P_2O_7$, was prepared by solid state reaction. The variation of conductivities with the pressure $pH_2O$ or time were studied. The highest conductivity of $Ce_{0.95}Eu_{0.05}P_2O_7$ sample was observed in dry air atmosphere at $300^{\circ}C$ to be $1.1{\times}10^{-4}S{\cdot}cm^{-1}$ and in wet air atmosphere ($pH_2O=7.4{\times}10^3Pa$) at $100^{\circ}C$ to be $1.4{\times}10^{-3}S{\cdot}cm^{-1}$, respectively. The log ${\sigma}$ ~ log ($pO_2$) plot result indicated that $Ce_{0.95}Eu_{0.05}P_2O_7$ was almost a pure ionic conductor under high oxygen partial pressure and a mixed conductor of ion and electron under low oxygen partial pressure.