• 한국입자에어로졸학회지
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• 제15권3호
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• pp.105-113
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• 2019

The exhaust emissions from coal-fired power plants have received much attention because coal-fired power plants are the one of the largest sources of particulate matter (PM) emissions in South Korea. To measure the PM10 and PM2.5, we developed the novel diluter which is comprised of ejector and porous tube in series. The dilution ratio must be defined to calculate particle concentrations of the sampled air as well as to probe match for the isokinetic sampling. For this reason, we verified the dilution ratio of the developed diluter by the flow rate, numerical solution, gas concentration and particle concentration. The ejector-supplied flow rates were 10-50 L/min and the porous tube-supplied flow rates were 30, 50 L/min in this study. All methods above showed similar dilution ratios to each other within 10 % error rate. The dilution ratio was confirmed by comparing mass concentrations before and after the dilution process.

• 한국토양비료학회지
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• 제34권1호
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• pp.71-75
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• 2001

포화침출액의 전기전도도, ECe와 토양과 증류수를 1:5로 하여 측정된 EC1:5간의 직선 관계식의 경사 또는 희석 배수 (DF)에 대해 서로 독립적으로 발표된 연구 결과를 분석한 결과, DF는 CEC와 고도의 유의성을 보이는 부상관 관계에 있었다. 이 관계로부터 한국 대표 토양에 대한표토의 CEC로부터 산출한 DF는 사토에서 12.29, 식토에서 6.44이었다. 이 연구에서 포화수분점에 대한 조사가 이루어지지 않았으나, 측정된 EC1:5로부터 ECe를 추정할 때 토양의 CEC를 고려해야 하며, 제시된 토성에 따른 DF값의 적용이 바람직할 것으로 판단되었다.

• 한국식품과학회지
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• 제22권4호
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• pp.421-425
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• 1990

본 실험에서는 균주의 특성에 따른 유산균수 시험방법의 적합 여부를 알아보기 위해 액상요구르트 제품들을 유효기간 중 여러 실험조건으로 비교 검토하였다. 비교한 실험조건은 배지(BCP, Elliker agar), 배양상태(aerobic, anaerobic), 희석수(saline, phosphate buffer), 희석방법 (10배, 100배)이었으며 $37^{\circ}C$에서 72시간 배양하였다. L. acidophilus 균주를 사용한 액상요구르트의 경우, 배지와 희석방법에 따른 차이는 거의 없었고 희석수와 배양상태에서는 약간의 차이가 있었다. L. jugurti 균주와 L. acidophilus +L. casei 혼합균주의 생우 배지 배양상태, 희석수에서 차이가 있었고 희석방법에는 거의 차이가 없었다. L. casei의 경우 배지, 희석방법에서 약간의 차이를 나타했으며 배양상태는 유산균수에 영향이 없었다. L. bulgaricus의 경우는 배지, 배양상태, 희석방법에 따라 차이가 있었고 희석수는 차이가 없었다. 그러므로 요구르트의 유산균수 측정은 균주의 종류에 따라 가장 좋은 실험조건을 선택하여 실시하는 것이 효과적인 시험방법으로 사료된다.

• Journal of Korean Biological Nursing Science
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• 제12권2호
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• pp.73-80
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• 2010

Purpose: We tested the inhibitory effect of six purchasable alcohol hand rubs against Staphylococcus aureus. Methods: Five alcohol hand rubs were collected with random manner on the market and 1 alcohol hand rubs which is currently used in a hospital was included. we designed the experimental scheme on the basis of M7-A6 method of NCCLS. Each hand rubs were diluted to 1:1, 1:10, 1:100, 1:1,000 with tryptic soy broth. S. aureus was cultured. Turbidity and the colony counting was measured. Results: With dilution rate of 1:1, all products showed more than 95% of the inhibitory effect on bacterial growth. At 1:10 dilution, product $N^{\circ}1$, 2, 3, 4, and 5 displayed the inhibitory effect of 97.77%, 92.38%, 78.19%, 97.42%, and 96.6%, respectively. But, the inhibitory effect of product $N^{\circ}6$ has been disappeared at that dilution. Over 1:100 dilution, all products lost their inhibitory effect except product $N^{\circ}5$. Product $N^{\circ}5$ displayed more than 96% of inhibitory effect at all dilution rate, even at 1:100 and 1:1,000. Conclusion: We identified that inhibitory effect on bacterial growth of alcohol hand rubs was variable. We suggest that concentration of alcohol should be checked before choosing alcohol hand rubs. Further evaluation of in vivo study is needed.

• 한국식물병리학회지
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• 제3권3호
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• pp.198-202
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• 1987

밀 보리에서 crown root rot 및 leaf blotch를 이르키는 Helminthosporium sativum의 독소물질을 분리하였다. 이는 독소물질에 대한 어떤 손상도 없이 C-18 column으로 분리되었으며, 실험적으로 가능한 inhibitor를 제거하였다. Lettuce 성장과 독소물질의 농도의 반응에는 semi-log 표에서 비례하였다. 또한 pathogen host인 밀 보리의 뿌리 성장에 사용한 결과 Lettuce의 반응과 동일한 결과를 얻었다. 또한, pathogen host인 밀 보리의 뿌리 성장에 사용한 결과 Lettuce의 반응과 동일한 결과를 얻었다. 독소물질과 식물의 반응을 측정하여 dilution end-points.의 결과로, 직접적으로 독소물질의 농도를 측정하는 방법을 개발하였다. (Y=a log x+b)의 공식과 통계처리로 사용하여 얻은 a와 b의 의미를 토론하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제33권5호
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• pp.637-645
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• 2009

The main purpose of this study lies on the improvement of micro dilution tunnel based on the typical porous tube type chamber. The characteristics of flow and temperature fields for steady state has been obtained by numerical analysis using FLUENT. Three different geometrical variations of the porous tube; a) increase of thickness at center, b) step increase of thickness at center and downstream, c) tapered increase of thickness, have been proposed. Accordingly results are obtained and compared in terms of penetration velocity and velocity ratio to therrmophoretic velocity for improvement against particulate deposition inside the tube. The penetration velocity and velocity ratio distributions in the upstream portion and portion of impinging of dilution air are apparently shown to be improved for the case of the step and tapered change of porous tube. The tapered change of tube thickness addition are shown to be the most effective among three geometrical changes. In addition, the considerable improvement against deposition are shown that its thickness should be at least 2mm.

• 한국표면공학회지
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• 제50권4호
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• pp.231-236
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• 2017

The present work addresses how to measure the amount of dissolved aluminum in phosphoric acid, based on volumetric and gravimetric measurements of the precipitates formed by reaction between the $H_3PO_4$ solution containing dissolved aluminum ions and 10 % KF solution. The volume of the precipitates increased with dilution of the dissolved aluminum-containing $H_3PO_4$ solution up to 1/4 dilution above which it decreased with further dilution. The lowered amounts of the precipitates at low dilution less than 1/4 and high dilution more than 1/4 are attributed to high acidity of the solution and decreased amount of dissolved aluminum in the solution, respectively. Volumetric measurement of the amount of precipitates was found not to be very reliable with the experiments, while weight measurement of the precipitates after drying for 80 min at $60^{\circ}C$ appeared to be very reproducible. In the present work, it is suggested that the amount of Al dissolved in 85 % $H_3PO_4$ solution can be calculated by multiplying 50 to the weight of precipitate obtained by reacting 8 ml of 1/4 diluted $H_3PO_4$ solution containing dissolved aluminum ions with 6 ml of 10 % KF solution.

• 분석과학
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• 제13권6호
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• pp.789-801
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• 2000

본 연구에서는 isotope dilution HRGC/HRMS 방법으로 저니토중의 PCDDs/PCDFs를 분석하였다. 분석결과 surrogate 표준물질의 평균 회수율은 70.1-80.8%로 양호하였다. 17종의 2, 3, 7, 8-치환이성체 분포에서는 OCDD가 총 농도의 40.6-78.5%를 나타내었으며, OCDF는 6.6-14.7%, 1, 2, 3, 4, 6, 7, 8-HpCDD는 5.1-7.7%를 나타내었다. 또한 PCDDS가 총 PCDDs/PCDFs중 62.4-86.9%를 나타내었다. TEQ 농도분포에서는 2, 3, 4, 7, 8-PeCDF가 22.7-35.6%를 나타내었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1499-1504
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• 2004

Flue gas recirculation (FGR) is a method used to control oxides of nitrogen ($NO_x$) in combustion system. The recirculated flue gases resulted in slow reaction and low flame temperatures, which in turn resulted in decreased thermal NO production. Recently, it has been demonstrated that introducing the recirculated flue gas in the fuel stream, that is, the fuel induced recirculation (FIR), resulted in a much greater reduction in $NO_x$ per unit mass of recirculated gas, as compared to introducing the flue gases in air. In the present study, the effect on $NO_x$ reduction in turbulent swirl flame in laboratory scale using FGR/FIR methods through the dilution using $N_2$ and $CO_2$. Results. show the $CO_2$ dilution is more effective $NO_x$ reduction methods because of large temperature drop due to the larger specific heat $CO_2$ compared to $N_2$. FIR is more effective to reduce $NO_x$ emission than FGR when the same recirculation ratio of dilution gas.

• International Journal of Oral Biology
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• 제46권2호
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• pp.94-97
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• 2021

The purpose of this study was to introduce a new in vitro method for evaluating the antimicrobial activity of toothpaste, reflecting the actual toothbrushing time and the dilution of toothpaste by salivation. We designed three experimental groups and one negative control group. The experimental groups were (1) 90 μL of toothpaste + 10 μL 1X phosphate-buffered saline (PBS, 9/10 dilution group), (2) 50 μL of toothpaste + 40 μL 1X PBS (1/2 dilution group), and (3) 25 μL of toothpaste + 65 μL 1X PBS (1/4 dilution group). During toothbrushing, saliva is continuously secreted into the oral cavity and the toothpaste concentration is diluted over time during toothbrushing. Therefore, the 1/2 and 1/4 dilution experimental groups were added. The negative control group was toothpaste diluted 20,000-fold with 1X PBS. Miracle Fresh Doctor toothpaste and Streptococcus mitis KCOM 1350, Prevotella intermedia KCOM 1107, Fusobacterium nucleatum subsp. polymorphum KCOM 1322, and Aggregatibacter actinomycetemcomitans KCOM 1306 were used as the toothpaste and target bacterial strains, respectively. The number of bacterial cells plated on agar plates in the negative control group was 1,000 CFU. If the number of colonies on the experimental group plate was less than one, the treatment was considered to have > 99.9% bactericidal activity. These results suggest that this new in vitro method for antimicrobial evaluation could be used as the standard method for testing the antimicrobial activity of toothpaste.