• 상하수도학회지
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• 제18권3호
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• pp.312-319
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• 2004

The optimum dosage control is presumably the goal of every water treatment plant. However it is difficult to determine the dosage rate of coagulant, due to nonlinearity, multivariables and slow response characteristics, etc. To deal with this difficulty, the real number genetic-fuzzy system was used in determining the dosage rate of the coagulant. The genetic algorithms are excellently robust in complex optimization problems. Since it uses randomized operators and searches for the best chromosome without auxiliary informations from a population which consists of codings of parameter set. To apply this algorithms, we made the real number rule table and membership function from the actual operation data of the water treatment plant. We determined optimum dosages of coagulant(LAS) using the fuzzy operation and compared them with the dosage rate of the actual operation data.

• 대한환경공학회지
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• 제30권10호
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• pp.1047-1053
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• 2008

돈분폐수 처리수의 색도를 제거하기 위해 최적의 응집 조건에 대하여 평가하였다. 유출수의 용존 유기 탄소 농도는 227.3 mg/L, 색도는 2,430 CU, 탁도는 22.1 NTU, 그리고 UV$_{254}$는 3.7 cm$^{-1}$이었다. 유출수의 소수성 유기물은 55.3%, 반친수성 유기물은 17.4%, 그리고 친수성 유기물은 27.3%로 세분화하였다. 또한, 겉보기 분자량 분포는 0.5 K 이하, 0.5$\sim$1 K, 1$\sim$10 K, 10$\sim$30 K 및 30 K 이상은 각각 74.2%, 7.3%, 5.5%, 7.1% 및 5.9%이었다. 최적의 pH 및 응집제 주입량을 결정하기 위해 유동전류계를 사용하였다. 황산알루미늄과 염화 제 2철의 최적 응집제 주입량 및 pH는 각각 5.84 mM, pH는 5.3이며, 9.25 mM, pH는 5.0이었다. 최적의 응집 조건에서 황산알루미늄과 염화 제 2철은 각각 91.9%와 98.7%로 높은 색도 제거 효율을 얻었다. 생물학적 처리를 거친 돈분폐수는 화학적인 응집으로 색도제거에 좋은 성과를 보여주었다.

• 한국환경과학회지
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• 제11권9호
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• pp.955-960
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• 2002

The recycled washwater, which has different water quality and is produced about 5 to 20% of the total water volume treated, affects the unit operation of water treatment, especially coagulation process. However, the effects of recycled washwater on unit operation of water treatment have not been fully investigated. In this study, effects of recycled washwater on coagulation process were investigated to find the optimum coagulation condition by analyzing turbidity, $UV_{254}$, TOC removal efficiencies. In addition, effects of recycled washwater on residual Al after coagulation were studied by analyzing soluble and particulate Al. The size distribution and fractal dimension of coagulated also analyzed. The recycled washwater was lower pH than the raw water. And the recycled washwater had higher $UV_{254}$, TOC and residual Al concentration than the raw water. Residual Al concentration of recycled washwater was about 50 times higher than that of raw water. Optimum coagulant dosages on the blending recycled washwater and the raw water for turbidity, $UV_{254}$ and Al removal were lower than that on the raw water. However, TOC removal increased by increasing coagulant dosage. The size and fractal dimension of coagulated particle produced in the blending recycled washwater were larger, which imply faster settling velocity, than those produced in the raw water only.

• Computers and Concrete
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• 제30권3호
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• pp.165-173
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• 2022

The effect of basalt and polypropylene fibers on the flexural behavior of reinforced concrete (RC) beams is investigated in this paper. The compressive and tensile behaviors of the basalt concrete and polypropylene concrete cylinders are also investigated. Eight beams and 28 cylinders were made with different percentages of basalt and polypropylene fibers. The dosages of fiber were selected as 0.6%, 1.3%, and 2.5% of the total cement weight. Each type of fiber was mixed solely with the concrete mix. Basalt and polypropylene fibers are modern and cheap materials that can be used to improve the structural behavior of RC members. This research is designed to find the optimum percentage of basalt and polypropylene fibers for enhancing the flexural behavior of RC beams. Test results showed that the addition of basalt and polypropylene fibers in any dosage (0.6%, 1.3%, and 2.5%) can increase the flexural strength and displacement ductility index of the beams where the maximum enhancement was measured with 1.3% fibers. The maximum increments in the flexural strength and the displacement ductility index were 30.39% and 260% for the basalt fiber case, while the maximum improvement for the polypropylene fibers case was 55.5% and 230% compared to the control specimen. Finite element (FE) models were then developed in ABAQUS to predict the numerical behaviour of the tested beams. The FE models were able to predict the experimental behaviour with reasonable accuracy. This research confirms the efficiency of basalt and polypropylene fibers in enhancing the flexural behavior of RC beams, and it also suggests the optimum dosage of fibers.

• 한국식품과학회지
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• 제4권1호
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• pp.29-35
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• 1972

방사선 조사가 감자 괴경(塊莖)의 맹아억제(萌芽抑制) 및 영양가에 미치는 효과를 규명하기 위해서 0 krad로부터 16 krad 사이의 선량(線量)을 Irish Cobbler 품종(品種)에 처리하였다. 싹 생장량은 선량이 높아짐에 따라 감소되었고 16 krad 처리구에서 완전히 억제되었다. 이 최적선량에서 괴경(塊莖)의 중량 손실은 현저히 감소했고 전(全)저장 기간을 통해 경도(硬度)는 양호했다. 방사선 조사는 감자 괴경(塊莖)의 cooking quality에 아무런 악(惡)영향도 미치지 않았다. 저장 후에 괴경(塊莖)내의 수분함량은 싹 생장량과 역비례(逆比例)하였다. 본 실험에서 16 krad 처리구는 탄수화물 함량이 저선량(底線量)처리구보다 다소 높은 경향을 보였고, ascorbic acid는 8 및 16 krad가 무처리구 및 2 krad 보다 다량 함유되고 있음이 나타났다.

• 한국환경과학회지
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• 제14권8호
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• pp.723-737
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• 2005

The effects of pH (5, 7 and 9) and ionic strength of different salts on the flocculation characteristics of humic acid by inorganic (alum, polyaluminum chloride (PAC) with degree of neutralization, r=(OH/Al) of 1.7) and organic (cationic polyelectrolyte) coagulants, have been examined using a simple continuous optical technique, coupled with measurements of zeta potential. The results are compared mainly by the mechanisms of its destabilization and subsequent removal. The destabilization and subsequent removal of humic acid by PAC and cationic polyelectrolyte occur by a simple charge neutralization, regardless of pH of the solution. However, the mechanism of those by alum is greatly dependent on pH and coagulant dosage, i.e., both mechanisms of charge neutralization at lower dosages and sweep flocculation at higher dosages at pH 5, by sweep flocculation mechanism at pH 7, and little flocculation because of electrostatic repulsion between negatively charged humic acid and aluminum species at pH 9. The ionic strength also affects those greatly, mainly based on the charge of salts, and so is more evident for the salts of highly charged cationic species, such as $CaCl_2$ and $MgCI_2.$ However, it is found that the salts have no effect on those at the optimum dosage for alum acting by the mechanism of sweep flocculation at pH 7, regardless of their charge.

• Ocean Science Journal
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• 제41권4호
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• pp.221-226
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• 2006

More attention has been paid to the research on decolorization of dyeing wastewater nowadays. In this study, an investigation into the decolorization of dyeing wastewater was conducted using a combination of coagulant, carboxymethyl chitosan (NOCC) and coagulant aid, polyscrylamide (PAM). The factors influencing the decolorization efficiency, such as pH value, coagulant and the dosages of coagulant, were discussed. The results showed that using PAM as coagulant aid could reach a high decolorization efficiency compared with using NOCC alone. The optimal conditions were pH 2.3, 480 mg/L for NOCC, and 4-8 mg/L for PAM. Under the optimum conditions, the rate of decolorization could achieve 99%, and the removal of chemical oxygen demand (COD) could achieve 90%. In addition, the membrane processes with chitosan/rare-earth-metals could enhance the decolorization rate of Direct Black FF to 94.7%, and Indanthren Red F3B to 98.2%, respectively.

• 아시안잔디학회지
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• 제2권1호
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• pp.65-69
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• 1988

This experiment was conducted to study the effects of herbicides and their damages to lawn plant for the control of lawn weeds using pre-emergence granule herbicide at the two years old lawn field. The results obtained are summarized as follows. 1)Herbicidal damages to lawn grass were observed at the higher concentration than the recommended level in four herbicides used in this trial. The optimum dosages for the control of lawn weeds were 3-6g in Lasso, 3g in Machet, 8-24g in Simazine, and 4g in Trifluralin, respectively. 2)No herbicidal damages was observed in Simazine treatment, whereas Lasso and Machet treatment showed a little and severe herbicidal damages, respectively. The most severe damage was found in Trifluralin treatment, indicating that this herbicide is not suitable for the control of lawn weeds.

• Elastomers and Composites
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• 제48권1호
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• pp.39-45
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• 2013

Haake Rheocorder로 각종 과산화물 개시제를 사용하여 ethylene-propylene-diene terpolymer (EPDM)에 단량체 citraconic acid (CCA)을 용융 그라프트 중합을 하여 그라프트 중합물 CCA-g-EPDM을 얻었으며, 이때 효율적인 그라프트 정도와 우수한 성능을 지닌 그라프트 중합물을 얻기 위해서 최적의 반응조건과 최적의 단량체/개시제 농도를 찾는 것은 매우 중요하다. 따라서 본 연구에서는 반응조건과 단량체 및 개시제 함량이 CCA-g-EPDM의 그라프트 정도, 그라프트 효율, 가교정도 (겔화도), 용융흐름지수(MI) 및 기계적 물성 등에 미치는 영향에 초점을 맞추었다. 그라프트 정도와 가교도가 증가함에 따라서 인장강도는 상당히 증가한 반면, 파괴신도 및 MI는 감소하였다. 개시제 중에서 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101)가 가장 우수한 그라프트 정도 (2.31%)를 나타내었으며, CCA와 T-101의 함량이 증가함에 따라 그라프트 정도가 크게 증가하였다. 그리고 그라프트 정도는 반응(혼합)온도 및 반응시간이 증가함에 따라 역시 증가하다가 어느 온도/시간 이상에서는 안정화 혹은 약간 감소하는 경향을 나타내었다. 이러한 영향으로 결과로부터 최적의 단량체/개시제 농도는 5/0.05 wt%이었으며, 최적의 반응온도/시간은 $180^{\circ}C$/15분인 것을 알 수 있었다.

• KSBB Journal
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• 제19권4호
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• pp.245-249
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• 2004

천연 식품 소재로 널리 사용되는 효모 추출물을 제조하는 공정의 개선을 위하여 제빵용 효모를 이용하여 자기소화법과 효소처리법을 병용하여 효모 추출물을 제조하였다. NaCl과 에탄올이 효모의 자기소화에 영향을 미치는 인자이었으며 최적 첨가량은 각각 3%와 1%이었다. 효모의 열처리와 효모 세포벽 분해효소의 사용은 유의하지 않았다. 효모를 자기소화 시킨 후 단백질 분해효소와 핵산 분해효소를 처리하고 Maillard 반응과 debittering 공정을 거쳐 효모 추출물을 제조하였다. 최종적으로 얻어진 효모 추출물의 수율은 고형분 기준으로 76%, 총 질소 기준으로 59%이었다. 맥주 효모를 이용한 결과와 비교하면 제빵용 효모를 이용하는 것이 맥주 효모를 이용하는 것보다 수율면에서도 유리하였다.