• 환경위생공학
• /
• 제13권1호
• /
• pp.185-194
• /
• 1998

Laboratory-scale investigation into initial anaerobic biofilm development was carried out by circulating mixed liquor from a steady-state anaerobic reactor through silicone tubing and then rerurning the mixed liquor to the reactor. The wall of the silicone tubing was the surface upon which anaerobic biofilm accumulation or development was monitored. Methanogenic bacteria accumulation was monitored by F$_{420}$ fluorescence (picomoles F$_{420}$/cm$^{2}$) of the extracted biofilm material. Biofilm accumulation was measured by the increase in COD of the extracted material ($\mu $g COD/cm$^{2}$). Experiments were conducted for 25 days, and biofilm analyses were performed at 5 days intervals. The results indicated that the initial rates of methangen and anaerobic biofilm accumulation increased with increasing organic loading rate and higher initial rates were observed for 15 days than 15 day liquid HRT or SRT. When the initial rates were plotted against the corresponding mixed liquor volatile suspended solids the difference between the results at the two HRT's became much less significant. Thus, the concentration of mixed liquor volatile suspended solids was found to be a very important parameter affecting initial anaerobic biofilm development. The ratio of methanogens to anaerobic biofilm was also investigated. The results showed that the ratio remained constant through the 25 days of each experiment and for high organic loading rates. Based on the results of this research, a reduction, a reduction of start-up period of anaerobic fixed film reactors might be achieved by maintaining a high organic loading and a large concentration of anaerobic microorganisms in the mixed liquor during the start-up period.

• 한국식품영양학회지
• /
• 제31권6호
• /
• pp.873-882
• /
• 2018

This research is about the quality characteristics of white bread mixed with varying ratios of Seomcho powder, such as 1%, 3%, 5%, and 7% (Spinacia oleracea L.). The pH level of dough decreased as more Seomcho powder (Spinacia oleracea L.) was added, and 7% addition recorded the lowest pH. The fermentation power of dough expansion decreased as the additional ratio increased in both the first and second proofing, and it was negatively correlated to the fermentation time factor. The moisture content of bread decreased as the addition ratio increased. The bread volume became smaller as the addition ratio increased, but it correlated negatively with its specific volume. The color of the crumb, the lightness and redness decreased in comparison to the control, but the yellowness increased. The total amino acid contents increased as the addition ratio increased, and glutamic acid was positively correlated to the additional ratio. The total free amino acids increased as the additional ratio increased, but cysteine levels were high at 5% and 7% additional ratio. The textural characteristics of the bread, springiness and cohesiveness were lower than the control, but gumminess, brittleness, and hardness were higher than the control. The adhesiveness was realized at 7% additional ratio.

• 한국지반공학회논문집
• /
• 제21권4호
• /
• pp.13-20
• /
• 2005

본 연구에서는 혼입재료의 혼합비와 입자 형태에 따른 혼합토의 압밀 거동 특성을 평가하고자 압밀 시험과 수치해석을 실시하였다. 실험 대상인 혼합토는 매질인 준설점토와 혼입재료인 파쇄된 굴패각(혹은 모래)으로 구성하였다. 응력분담률이라는 개념을 이용하여 혼합토의 압밀특성을 파악하고 Mikasa압밀이론을 이용한 유한차분 수치해석을 실시하였다. 그 결과, 혼입재료에 따라 혼합토의 압밀 거동에 차이가 있음을 증명하였다. 같은 양의 조립재가 혼합되어 있는 경우 굴패각 혼합토의 점토 매질의 압축성이 모래혼합토의 경우보다 작게 나타났다.

• 한국건설순환자원학회논문집
• /
• 제7권1호
• /
• pp.44-49
• /
• 2019

본 연구는 서로 다른 입도의 단일골재 및 반대 입도의 골재를 혼합한 혼합골재에 리젝트애시(Reject ash=Rj)의 치환율 변화에 따른 콘크리트의 기초적 특성을 분석함으로써 골재 제조공장에서 프리믹스하여 1개의 골재로 납품하는 혼합골재 시스템의 가능성을 분석하였다. 실험연구결과 입도규정의 경우는 혼합골재(CSb+SS)에 Rj를 5% 정도 치환할 경우 입도규정을 만족하는 것으로 나타났다. 유동성인 슬럼프 및 슬럼프 플로와 공기량의 경우에는 Rj의 치환율 증가에 따라 감소하는 것으로 나타났으나, 압축강도의 경우에는 Rj의 치환율이 증가함에 따라 증가하는 것이 확인되었다. 따라서 매립 처분되는 Rj를 5% 정도 혼합골재에 프리믹스하여 활용하면서 감수제 및 AE제 등으로 적정 유동성 및 공기량은 확보하여 준다면 압축강도 증진 등 품질향상에 크게 기여할 것으로 분석되었다.

• 대한기계학회논문집B
• /
• 제34권5호
• /
• pp.481-489
• /
• 2010

수직관내 발달 유동의 층류혼합대류에 관한 본 연구는 Re 1,000에서 3,000, $Gr_H\;10^5$에서 $10^8$, Pr 2,000 에서 7,000 그리고 종횡비 1부터 7에 대한 범위에 대해서 수행되었다. 유사성(Analogy)의 원리를 이용하여 수직관내 발달 유동의 층류혼합대류 열전달계를 물질전달계로 모사하였다. 물질전달계로써 Nu 수는 기존의 문헌들의 그것들보다 상당히 큰 값이었는데, 이는 본 실험의 높은 Pr 수 때문이다. 본 연구에서의 종횡비는 완전발달 할 만큼 크지 않았기 때문에, 실험 결과는 긴 수직관내 혼합대류 유동보단 평행평판에서의 혼합대류 유동과 유사하였다. 본 연구의 결론으로서 낮은 종횡비와 $Gr_H$ 수를 갖는 수직관내 발달 유동의 층류혼합대류 유동은 수직 평판에서의 층류혼합대류 유동과 유사한 거동을 보인다는 것이다. 그리고 종횡비와 $Gr_H$ 수가 증가할 때 유체의 거동은 수직관내 완전발달 유동과 유사한 현상을 보였다.

• 한국작물학회지
• /
• 제53권spc호
• /
• pp.44-46
• /
• 2008

경북지역에서 생산 유통되는 브랜드 쌀의 품질 분석을 통해 고품질 쌀 생산의 기초 자료로 활용하고자 하였으며, 분석시료로는 경북 시군에서 추천한 2006-2007년도 브랜드 쌀 26종을 사용하였다. 단백질 함량은 6.5%이하가 46.2% (12종), 6.6%-7.0%는 23.1%(6종)로 비교적 낮아 단백질 함량은 양호하였다. 완전립율은 95% 이상이 7.7%(2종), 90-94%는 15.4%(4종)이었으며 89% 이하가 76.9%(20종)로 품질이 다소 낮았으며 분상질립은 다소 높아 완전립율과 분상 질립 개선이 필요하다. DNA 분석에 의한 품종 혼입율 분포는 1-10%가 46.2%(12종), 11-20%는 34.6%(9종)로서 순도 80% 이상이 80.8%로서 매우 양호하였다.

• 한국조리학회지
• /
• 제23권8호
• /
• pp.163-172
• /
• 2017

In order to investigate the quality characteristics of Prunus persica Batsch var. davidiana Max. preserved in sugar, the quality characteristics were examined by dividing them into four groups: PS-A (P. persica preserved in sugar mixed with sucrose and oligosaccharides at a ratio of 100:0, w/w), PS-B (P. persica preserved in sugar mixed with sucrose and oligosaccharides at a ratio of 60:40, w/w), PS-C (P. persica preserved in sugar mixed with sucrose and oligosaccharides at a ratio of 40:60, w/w) and PS-D (P. persica preserved in sugar mixed with sucrose and oligosaccharides at a ratio of 0:100, w/w). The results were as follows: pH levels and soluble solid contents of PS-D sample were lower than those of the others, however total acidity value were higher. In case of Hunter's value, the 'L', 'a' and 'b' values of all samples were affected by addition of oligosaccharides. No great difference occurred among samples in reducing sugar contents. Organic acid content was significantly decreased with the lower addition of sucrose. The predominating organic acid components analyzed in all samples were lactic acid 156.15 g/100 g, tartaric acid 72.75 g/100 g and citric acid 32.90 g/100 g. The highest contents of total phenol and flavonoid, and DPPH and ABTS radical scavenging activity were $10.79{\pm}0.55mg\;GAE/mL$, $8.71{\pm}0.06mg\;CE/mL$ and 71.8%, 71.0% for PS-D, respectively. The results of this study indicated the use of oligosaccharides could increase the quality and antioxidant potentials of P. persica preserved in sugar.

• KSBB Journal
• /
• 제28권3호
• /
• pp.157-164
• /
• 2013

Depending on season, mixed wastewater can show great deviations in terms of the influent ratios of tannery and seafood-wastewater. Increases in the ratio of tannery wastewater in influent water also result in increases in the concentration of chromium, which decreases the ratio of BOD/T-N so that the removal efficiency of organic and nitrogen pollutants in biological wastewater treatment deteriorates. No substantial differences occur in the ratios of Eubacteria/total bacteria as the ratio between tannery wastewater and seafood wastewater changes in the influent water. In contrast, the cell numbers and activities of Eubacteria and total bacteria significantly decline with increasing ratios of tannery wastewater in the influent water. Stable removal of organic and nitrogen pollutants by biological wastewater treatments leads to dominance of Proteobacteria groups in all biological treatment basins. In aeration and oxic basins, ${\gamma}$-Proteobacteria account for approximately 21% of the Eubacteria groups, at $1.9{\times}10^9{\sim}2.0{\times}10^9$ cells/mL, while in an anoxic basin, ${\beta}$-Proteobacteria account for approximately 19% of the Eubacteria groups, at $1.3{\times}10^9$ cells/mL. However, a substantial decline in dominance of approximately 11% occurs for ${\gamma}$-Proteobacteria in aeration and oxic basins and about 1% for ${\beta}$-Proteobacteria in an anoxic basin. Mixed wastewater that undergoes extensive property changes of the influent water shows an efficiency of biological treatment that is greatly influenced by the ratio of dominant Proteobacteria groups.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 춘계 학술발표회
• /
• pp.805-812
• /
• 2009

Permeation water resulting in the reclaimed land of waste can possibly cause the second pollution, such as the underground water and environmental pollution. Accordingly, Liner layer has been installed in the reclaimed land of waste to block and purify permeation water and prevent this second pollution. The material used as Liner layer is the one for water resistance and that of less than permeability coefficient $1{\times}10^{-7}cm/sec$ is widely used. As it is very difficult to secure in bulk this natural clay with low permeability around the field, the suitable way to secure low permeable material is that we use blend with good watertighness by mixing it with natural soil which is spread in the site. While this mixed soil which can resist water is commonly used in the site, bentonite mixed soil which is widely used as Liner layer in the reclaimed land of waste is recognized in Liner and durability. In this study, the engineering characteristics of soil-bentonite mixed liner are investigated using the laboratory hydraulic conductivity and uni-axial strength tests. The soil used for the liner is the clay soil located near the site. Mixing ratio of the bentonite which satisfies the requirement of hydraulic conductivity is determined and the optimum mixing ratio of bentonite is recommended for the landfill. After the mixed liner is constructed using the optimum mixing ratio of bentonite, the block samples of the constructed liner are obtained and the strength tests were performed. The hydraulic and strength properties of the liner for construction of the waste landfill were both satisfactory.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
• /
• pp.465-468
• /
• 2008

본 연구는 영, 호남 지역의 레미콘 공장에서 현재 사용하고 있는 잔골재의 특성을 분석하고, 혼합사용 시 잔골재율 조정에 따른 콘크리트의 특성실험을 통하여 혼합사용 시 최적조건을 분석한 것으로 그 결과를 요약하면 다음과 같다. 영, 호남에서 사용하는 골재 종류별 물성은 조립률 및 0.08mm체 통과량을 제외하고 모두 KS F 2526 및 KS F 2527의 규정에 적합한 것으로 나타났는데, 각 공장에서는 단독사용이 부적합한 골재를 2종 이상 적절한 비율로 혼합사용하고, KS규정에 적합하게 품질을 관리하고 있었다. 영, 호남 각 공장에서 단위용적질량법에 의해 산출한 잔골재율로 조정한 콘크리트의 배합은 기존의 출하배합보다 높은 유동성을 보이는 것으로 나타났는데, 이는 잔골재율 약 2% 저감에 따라 잔골재의 표면적 감소 및 공극감소에 따른 시멘트 페이스트의 유동성에 미치는 잉여수량의 상대적 증가에 기인한 것으로 분석된다. 따라서 최적 잔골재율을 적용함으로써 단위수량 감소로 인한 경제적인 콘크리트 배합과 콘크리트의 내구성을 증진시키는 효과가 있을 것이라 사료된다.