• KSBB Journal
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• 제4권2호
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• pp.134-142
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• 1989

Aureobasidium pullulans에 의한 세포외 다속류 생성연구를 통한 결론은 다음과 같다. (1) sucrose 농도가 50 g/l 이상일 때는 기질에 의한 저해 작용이 나타나고 있음을 알았으며 실소원의 증가에 따라서 균체량은 증가하지만 세포외 다속류 생성은 최적농도 (1 g/l )까지 증가하고 그 이상에서는 감소했으며 멜라닌 색소 출현시간은 길어졌다. (2) 최대 균체 성장은 초기 pH 3.0에서 보인 반면에 세포외 다속류 생성은 초기 pH 7.5에서 최대 값은 나타내었고 최대 PH가 증가함에 따라서 효모형 비율이 증가했으며 멜라닌 색소 출현시간은 pH 4.5~8까지는 거의 일정하게 나타났지만 pH 3 이하에서는 전혀 멜라닌 색소가 나타나지 않았다. (3) 탄소원과 실소원을 증가시켰을 때 pH 5 이하에서는 멜라닌 색소는 나타나지 않았으나 pH 6에서 pH 8.5 로 pH가 높아짐에 따라 멜라닌 색소는 빨리 나타나는 경향을 보였다. (4) 용존산소 농도가 높을수록 균체량과 세포외 다속류 생성이 증가했고 멜라닌 색소 출현시간이 빨라졌으며 potassium phosphate가 전혀 들어있지 않는 배지에서는 멜라닌 색소 출현은 관찰할수가 없었다.

• Fisheries and Aquatic Sciences
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• 제18권4호
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• pp.373-378
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• 2015

Postprandial ammonia excretion and oxygen consumption in olive flounder Paralichthys olivaceus fed two different feed types, moist pellet (MP) and expanded pellet (EP) diets, to satiation were determined at $12^{\circ}C$, $15^{\circ}C$, $20^{\circ}C$, and $25^{\circ}C$ for 48 h. The ammonia excretion and oxygen consumption rates increased with increasing water temperature. However, the postprandial times for the maximum rates of ammonia excretion and oxygen consumption were shortened from 12 h to 6 h after feeding with increasing water temperature. The ammonia excretion and oxygen consumption rates of the fish fed EP were significantly higher (P < 0.05) than those fed MP at 12 h post-feeding both for $12^{\circ}C$ and $15^{\circ}C$. The highest (P < 0.05) weight-specific ammonia excretion rates at $12^{\circ}C$ were observed in the fish fed EP and MP at $12.1mg\;NH_3-N\;kg^{-1}h^{-1}$ and $8.7mg\;NH_3-N\;kg^{-1}h^{-1}$, respectively, for 12 h and 9 h after feeding. The highest (P < 0.05) weight-specific oxygen consumption rates at $12^{\circ}C$ were observed in fish fed EP and MP at $116.4mg\;kg^{-1}h^{-1}$ and $101.0mg\;kg^{-1}h^{-1}$, respectively, for 12 h after feeding. The highest ammonia excretion rates at $25^{\circ}C$ in the fish fed EP and MP increased to $16.9mg\;NH_3-N\;kg^{-1}h^{-1}$ and $18.3mg\;NH_3-N\;kg^{-1}h^{-1}$, respectively, for 6 h after feeding. The highest (P < 0.05) weight-specific oxygen consumption rates at $25^{\circ}C$ were observed in fish fed EP and MP at $184.3mg\;O_2kg^{-1}h^{-1}$ and $197.3mg\;O_2kg^{-1}h^{-1}$, respectively. These data are valuable for the design of biofilters and development of effluent treatment technologies for the land-based flounder farms.

• Tribology and Lubricants
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• 제18권4호
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• pp.299-304
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• 2002

This paper reports the studies on the wear-corrosion behavior of ductile cast iron in the acidic environment. In atmosphere and variety of pH solution, specific wear rate and wear-corrosion characteristics of GCD 60 with various sliding speed and distance were investigated. And electrochemical polarization test of GCD 60 was examined in the environment of various pH values. The main results are as following : As the contact pressure increases, the critical velocity of specific wear rate becomes transient at low sliding speed. As pH value becomes low, wear-corrosion loss increases in the aqueous solution. As the corrosion environment is acidified, corrosion potential of GCD 60 becomes noble and corrosion current density increases.

• 한국식품과학회지
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• 제25권2호
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• pp.109-117
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• 1993

친수성 콜로이드를 식품에 유효하게 이용하기 위한 기초자료를 얻기 위하여 sodium alginate, gum karaya 및 gum arabic 등 3종의 고무질을 sodium caseinate에 첨가하였을 때 이들이 거품성에 비피는 영향을 검토하였다. 표면장력은 pH 7.0(대조구, 43.9 dyne/cm)에서 고무질의 종류 및 농도에 따라 $43.7{\sim}44.7\;dyne/cm$이었으며 pH 8.0(대조구, 42.7 dyne/cm)에서는 $43.6{\sim}44.0\;dyne/cm$이었다. 비점도는 sodium alginate 첨가시 pH 7.0에서 0.2 및 0.3% 첨가하였을 때 각각 15.6 및 39.1로써 대조구(2.8)에서 보다 크게 증가하였으며 pH 8.0에서도 12.1 및 8.2로써 대조구(2.6)에서 보다 증가하였다. Gum karaya 첨가시는 pH 7.0에서 0.1, 0.2 및 0.3% 첨가농도에 따라 $3.3{\sim}10.7$로써 대조구(2.6)에서 보다 증가하였으며 pH 8.0에서도 농도에 따라 $3.4{\sim}4.4$로써 다소 증가하였다. 혼탁도는 pH 7.0(대조구, 69.0)에서 고무질의 종류 및 농도에 따라 $69.5{\sim}74.0$, pH 8.0(대조구, 67.0)에서 $68.0{\sim}72.5$이었다. 거품형성능은 전체적으로 고무질 첨가구가 대조구에서 보다 떨어졌으며, 전체적으로 보아 pH 8.0에서 보다 pH 7.0에서가 다소 양호하였다. 거품형성을 위한 고무질의 첨가농도 및 whipping 시간을 보면, 전체적으로 보아 sodium alginate의 경우 0.1% 및 15분, gum karaya는 0.2% 및 20분, 그리고 gum arabic은 0.1% 및 10분이 비교적 양호한 조건임을 알 수 있었다. 거품안정성은 pH 7.0에서 sodium alginate 및 gum karaya가 0.3%, pH 8.0에서는 0.2%가 적절한 첨가농도이었으며 pH 8.0보다 pH 7.0에서가 더 양호하였다. 전체적으로 보아, 표면장력, 점도 및 혼탁도의 증감에 따른 거품형성능 및 안정성의 뚜렷한 증감은 보이지 않았으나, 동일 pH 영역에서는 표면장력과 혼탁도가 낮으면 거품형성능이 높아지고, 점도가 높으면 거품안정성이 증진되는 경향이 있었다.

• 한국재료학회지
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• 제33권10호
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• pp.430-438
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• 2023

In this study, we synthesized pH-controlled resorcinol-formaldehyde (RF) gels through the polymerization of two starting materials: resorcinol and formaldehyde. The prepared RF gels were dried using an acetone substitution method, and they were subsequently carbonized under nitrogen atmosphere to obtain carbon xerogels (CX_Y) prepared at different pH (Y). The carbon xerogels were utilized as active materials for coin-type organic supercapacitor electrodes to investigate the influence of pH on the electrochemical properties of the carbon xerogels. The carbon xerogels prepared at lower pH (CX_9.5 and CX_10) exhibited sufficient particle growth, with a three-dimensional network of particles during the RF gel formation, resulting in the development of abundant mesopores. Conversely, the carbon xerogels prepared at higher pH (CX_11 and CX_12) retained densely packed structures of small particles, leading to pore collapse and low specific surface areas. Consequently, CX_9.5 and CX_10 showed high specific surface areas, and provided ample adsorption sites for the formation of electric double layers with electrolyte ions. Moreover, the three-dimensional particle network in CX_9.5 and CX_10 significantly enhanced electrical conductivity. The presence of well-developed mesopores in these materials further facilitated the effective transport of electrolyte ions, contributing to their superior performance as organic supercapacitor electrodes. This study confirmed that pH-controlled carbon xerogels are one of the promising active materials for organic supercapacitor electrodes. Furthermore, we concluded that pH during RF gel formation is a crucial factor determining the electrode performance of the carbon xerogels, highlighting the need for precise pH control to obtain high-performance carbon xerogel electrodes.

• 전기전자학회논문지
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• 제20권2호
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• pp.181-183
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• 2016

탄화규소(Silicon Carbide) 기반의 1200 V급 Merged Pin Schottky(MPS) 다이오드의 구조를 2D-atlas simulation tool을 사용하여 최적화 및 설계하였다. 최적화된 항복전압과 온-저항 값을 얻기 위해 본 소자에서 중요한 파라미터인 P-Grid의 도핑농도와 에피층의 도핑농도를 각각 $2{\sim}10{\times}10^{17}cm^{-3}$, $2{\sim}10{\times}10^{16}cm^{-3}$으로 변화시키면서 소자의 전기적 특성을 분석하였으며, 그 후 P-Grid의 Space값을 $1{\sim}5{\mu}m$로 설계하여 이에 따른 항복전압과 온-저항의 값을 확인하였다. 항복전압과 온-저항은 서로 trade-off 관계에 있기 때문에 각 변수에서 도출된 값들을 Baliga's Figure Of Merit (BFOM)식에 대입하여 비교하였다. 그 결과 고전압 소자에 적용 가능한 1200 V급 4H-SiC MPS다이오드를 최적화 및 설계를 도출하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.105-106
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• 2017

Previous studies have confirmed the performance of pH reduction agents using liquid sodium phosphate based ammonium chloride as a pH reduction agent. In this study, the pH reduction performance considering economical and applicability as a practical stage and the property change analysis for the identification of the reaction mechanism of the pH reduction agent were carried out. As a result, the pH reduction performance at a low rate of the pH reducing agent was confirmed. The specific gravity of CaO decreased significantly after XRF analysis. It is also believed that this reduces the amount of Ca(OH)₂ produced and contributes to pH reduction.

• 한국수산과학회지
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• 제49권4호
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• pp.454-459
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• 2016

Pre- or post-harvest processing is required to mitigate the risk of norovirus infection mediated by shellfish or seafood. We investigated the environmental resistance of human norovirus (HuNoV) under various conditions of temperature, salinity, and pH in seawater. Male-specific coliphage (MSC) was as the reference virus for all tests. At 4℃, HuNoV GII4 spiked into seawater was continually detected by RT-PCR for 35 days, regardless of salinity or pH level. It maintained nearly stable concentrations, meaning HuNoV can sustain a viral population in seawater long enough to be accumulated by shellfish and other filter feeders during winter. MSC was also stable at 4℃ although viral infectivity dropped sharply after 28 days. The effects of salinity and pH on MSC were indistinct. At 25℃ the detectable period of HuNoV GII4 by RT-PCR in seawater decreased to about one-third or half of the period at 4℃. High salinity (32 psu) and alkaline pH (8.5) were also unfavorable for sustaining HuNoV abundance at 25℃ in seawater. The resistance patterns of MSC to high temperature, high salinity, and alkaline pH were more dramatic and viral infectivity decreased over time, almost in direct proportion to experimental days. MSC was undetectable after 12 days under all salinities and pH levels at 25℃.

• 한국조리학회지
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• 제16권4호
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• pp.305-311
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• 2010

스펀지 케이크 제조시 설탕의 10%에서 40%까지 sorbitol과 maltitol로 대체하여 케이크 반죽의 비중 및 pH와 스펀지 케이크의 제품 특성으로 부피 및 조직감을 측정하였다. 반죽의 1차 비중은 대조구에 비하여 sorbitol과 maltitol을 첨가한 시험구들에서 낮았고, 그 첨가량이 많을수록 낮았다. 2차 비중도 같은 결과로 첨가량이 많을수록 낮아졌고, maltiol보다는 sorbitol에서 더 낮은 결과를 보였다. 반죽의 pH는 대조구에 비하여 sorbitol과 maltitol을 대체하였을 때 높았고, 대체량이 많을수록 높아졌다. 케이크의 부피는 대조구에 비하여 sorbitol과 maltitol을 대체한 시험구에서 크게 나타났다. 대체량이 20%까지는 sorbitol에서 부피가 컸고, 30% 이상에서는 maltitol에서 크게 나타났다. 스펀지 케이크의 조직감으로 경도는 대조구가 가장 높았고, sorbitol과 maltitol을 대체한 시험구에서 낮게 나타났다. Sorbitol과 maltitol의 비교에서는 sorbitol을 첨가한 시험구가 다소 낮은 경도 값을 보였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 창립총회 및 춘계학술발표회
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• pp.52-55
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• 2000

The effects of environmental conditions, initial dissolved oxygen concentrations, pH, and the presence of electron carrier vitamin B$_{12}$ , on the reduction rate of TNT by Fe$^{0}$ was Quantitatively analyzed using a batch reactor. In all experiments, TNT reduction was best described with a first order reaction and the reduction rate decreased with the increase in the initial DO concentration. However, the specific reaction rate did not decrease linearly with the increase in the initial DO concentration. In the presence of HEPES buffer 0.2 and 2.0 mM(pH 5.7$\pm$0.2), the specific reaction rate increased more than 5.8 times, which showed reduction rate is rather significantly influenced by the pH of the solution. To test the possibility of reaction rate enhancement, well-known electron carrier(or mediator), vitamin B$_{12}$ has augmented besides Fe$^{0}$ . In the presence of 8.0 $\mu\textrm{g}$/L of vitamin B$_{12}$ , the specific reaction rate increased as much as 14.6 times. The results indicate that the addition of trace amount of vitamin B$_{12}$ can be a promising rate controlling option for the removal of organics using a Fe$^{0}$ filled permeable reactive barrier.