• Biotechnology and Bioprocess Engineering:BBE
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• 제11권1호
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• pp.54-60
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• 2006

In this paper, we describe a bio-fluidic device for adaptive sample pretreatment, in order to optimize the conditions under which absorbance assays can be conducted. This device can be successfully applied to the measurement of Escherichia coli (E. coli) concentrations using adaptive dilution, with which the dilution ratio can be adjusted during the dilution. Although many attempts have been previously made to miniaturize complex biochemical analyses at the chip scale, very few sample pretreatment processes have actually been miniaturized or automated at this point. Due to the lack of currently available on-chip pretreatments, analytical instruments tend to suffer from a limited range of analysis. This occasionally hinders the direct and quantitative analysis of specific analyses obtained from real samples. In order to overcome these issues, we exploit two novel strategies: dilution with a programmable ratio, and to-and-fro mixing. The bio-fluidic device consists of a rectangular chamber constructed of poly(dimethylsiloxane) (PDMS). This chamber has four openings, an inlet, an outlet, an air control, and an air vent. Each of the dilution cycles is comprised of four steps: detection, liquid drain, buffer injection, and to-and-fro mixing. When using adaptive sample pretreatment, the range in which E. coli concentrations can be measured is broadened, to an optical density (O.D.) range of $0.3{\sim}30$. This device may prove useful in the on-line monitoring of cell concentrations, in both fermenter and aqueous environments.

• 한국환경농학회지
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• 제38권2호
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• pp.69-75
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• 2019

BACKGROUND: Measurement of electrical conductivity of saturated soil paste ($EC_e$) for assessment of soil salinity is time-consuming, and thus conversion of EC of 1:5 soil-water extract ($EC_{1:5}$) to $EC_e$ using a dilution factor may be of help to monitor salinity of huge number of soil samples. This study was conducted to evaluate the dilution factor for reclaimed tideland (RTL) soils of South Korea. METHODS AND RESULTS: Soil samples (n=40) were collected from four RTLs, and analyzed for $EC_{1:5}$, $EC_e$, and cation compositions of 1:5 soil-water extract. The dilution factor (8.70) was estimated by regression analysis between $EC_{1:5}$ and $EC_e$, and the obtained dilution factor was validated by applying to an independent data set (n=96) of $EC_{1:5}$ and $EC_e$. The $EC_e$ measured and predicted was strongly correlated ($r^2=0.74$, P<0.001), but $EC_e$ was overestimated by 16% particularly for the soils with high clay content and low sodium adsorption ratio (SAR). CONCLUSION: This study suggests that using the dilution factor to convert $EC_{1:5}$ to $EC_e$ is feasible method to monitor changes in the soil salinity of the study RTL. However, overestimation of $EC_e$ should be cautioned for the soils with high clay content and low SAR.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3482-3488
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• 2014

Matrix-induced mass bias and its effect on the accuracy of isotope ratio measurements have been examined for a quadrupole-based inductively coupled plasma-mass spectrometer (Q ICP-MS). Matrix-induced mass bias effect was directly proportional to % mass difference, and its magnitude varied for element and nebulizer flow rate. For a given element and conditions in a day, the effect was consistent. The isotope ratio of Cd106/Cd114 under $200{\mu}g\;g^{-1}$ U matrix deviated from the natural value significantly by 3.5%. When Cd 111 and Cd114 were used for the quantification of Cd with isotope dilution (ID) method, the average of differences between the calculated and measured concentrations was -0.034% for samples without matrix ($0.076{\mu}g\;g^{-1}$ to $0.21{\mu}g\;g^{-1}$ for the period of 6 months). However, the error was as large as 1.5% for samples with $200{\mu}g\;g^{-1}$ U. The error in ID caused by matrix could be larger when larger mass difference isotopes are used.

• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.408-411
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• 2018

We fabricated highly flexible Mn-doped $SnO_2$ (MTO)/Ag/MTO/polydimethylsiloxane (PDMS)/MTO multilayer transparent conducting films. To reduce refractive-index mismatching of the MTO/Ag/MTO/polyethylene terephthalate (PET), index-matching layers were inserted between the oxide-metal-oxide-structured films and the PET substrate. The PDMS layer was deposited by spin-coating after adjusting the mixing ratio of PDMS and hexane. We investigated the effects of the index-matching layer on the color and reflectance differences with different PDMS dilution ratios. As the dilution ratio increased from 1:100 to 1:130, the color difference increased slightly, while the reflectance difference decreased from 0.62 to 0.32. The MTO/Ag/MTO/PDMS/MTO film showed a transmittance of 87.18~87.68% at 550 nm. The highest value of the Haacke figure of merit was $47.54{\times}10^{-3}{\Omega}^{-1}$ for the dilution ratio of 1:130.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
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• pp.90-96
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• 2001

Catalytic ignition of $H_2/O_2/CO_2$ mixtures over platinum catalyst is experimentally investigated by using microcalorimetry. For comparison, $N_2$ and Ar is also used as diluent gas. The gas mixture flows toward platinum foil heated by electric current at atmosphere pressure and ambient temperature. The ignition temperature range 350-445K according to the fuel ratio, dilution ratio and diluent gas. It increases as the fuel ratio and dilution ratio increase. $H_2/O_2$ mixture with $CO_2$ ignites at higher temperature than with other diluents by 30-50K. Several experimental evidences show the inhibition effects of $CO_2$ in $H_2-O_2$ heterogeneous reaction is considerable

• 한국수산과학회지
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• 제11권1호
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• pp.19-24
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• 1978

장염비브리오균 검사에 있어서 검출방법에 따른 검출율은 차이를 알아보기 위하여 부산지방을 중심으로 해수 298개 시료, 112개 시료, 패류 169개 시료 어류 80개 시료 총 659개 시료를 단일 시험관을 사용하였을 때와 다수의 시험관을 사용하였을 때, 원시료 또는 일단계희석하였을 때의 검출율를 비교 실험한 자료를 분석 검토하여 그 결과를 요약하면 다음과 같다. 1. 해수에 있어서 10 ml를 접종 배양할 때에 장염비브리오균 음성인데도 같은 시료에서 1/100 는 1/1000로 희석한 시료에서 장염비브리오균 양성으로 나타나는 경우가 많았다. 이러한 현상은 이토, 패류, 어류에서도 같은 경향이었다. 2. 총 659개 시료 중에서 $52\%$에 해당하는 343개 시료가 장염비브리오균 양성으로 판정되었는데 이중희석하지 않은 시료에서 이 균이 검출된 것은 $22.5\%$인 149개 시료에 불과하였다. 시료별로 보면 해수는 $50\%$ 중 $24.5\%$, 이토의 경우는 $65.2\%$ 중 $28.6\%$, 패류에서는 $56.2\%$ 중 $22.5\%$에 불과하였다. 3. 최확수법에 의한 장염비브리오균 검출율은 단일희석법으로 측정했을 경우의 2배 이상이었다. 4. 3개 시험관을 사용한 최확수법에 있어서 제일 낮은 희석단계에서 양성으로 판정된 것은 $28.9\%$, 3개의 시험관 모두가 양성인 것은 $9.4\%$뿐이었다.

• 한국재료학회지
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• 제22권1호
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• pp.54-60
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• 2012

The particle size of MgO was examined as a function of the Na content in $Mg(OH)_2$ powders and the calcination temperature. $Mg(OH)_2$ suspension was obtained by dropwise precipitation of $Mg(NO_3)_2{\cdot}6H_2O$ and NaOH solutions. The suspension was diluted by varying the dilution volume ratio of distilled water to $Mg(OH)_2$ suspension to change the Na salt concentration in the suspension. $Mg(OH)_2$ slurry was filtered and dried at $60^{\circ}C$ under vacuum, and then its $Mg(OH)_2$ powder was calcined to produce MgO with different amount of Na content at $500\sim900^{\circ}C$ under air. Investigation of the physical and chemical properties of the various MgO powders with dilution ratio and calcination temperature variation was done by X-ray diffraction, transmission electron microscopy, BET specific surface area and thermal gravimetric analysis. It was observed that MgO particle size could depend on the condition of calcination temperature and dilution ratio of the $Mg(OH)_2$ suspension. The particle size of the MgO depends on the Na content remaining in the $Mg(OH)_2$ powder, which powder was prepared by changing the dilution ratio of the $Mg(OH)_2$ suspension. This change increased as the calcination temperature increased and decreased as the dilution ratio increased. The growth of MgO particle size according to the increase of temperature was more effective when there was a relatively high content of Na. The increase of Na content lowered the temperature at which decomposition of $Mg(OH)_2$ to MgO took place, thereby promoting the crystal growth of MgO.

• 한국전기전자재료학회논문지
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• 제34권4호
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• pp.246-250
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• 2021

TFTs technologies with as high mobility as possible is essential for high-performance large displays. TFTs using nanocrystalline silicon thin films can achieve higher mobility. In this work, the change of the crystalline volume fraction at different hydrogen dilution ratios was investigated by depositing nc-Si:H thin films using PECVD. It was observed that increasing hydrogen dilution ratio increased not only the crystalline volume fraction but also the crystallite size. The thin films with a high crystalline volume fraction (55%) and a low defect density (10¹⁷ cm^-3·eV^-1) were used as top gate TFTs channel layer, leading to a high mobility (55 cm²/V·s). We suggest that TFTs of high mobility to meet the need of display industries can be benefited by the formation of thin film with high crystalline volume fraction as well as low defect density as a channel layer.

• 한국식품과학회지
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• 제27권1호
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• pp.129-133
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• 1995

배양환경이 효모 RNA 축적과 autolysis 효율에 미치는 영향을 알아보기 위하여 연속배양을 실시하였다. Dilution rate의 증가에 따라 균체내의 RNA 함량은 증가하여 dilution rate=0.35 $h^{-1}$에서 14.8%를 나타내었고, 더불어 RNA productivity와 specific RNA productivity도 증가하였다. 고정된 D=0.2 $h^{-1}$에서 최적 균체량은 배양온도 $30^{\circ}C$ 에서 얻어졌으나, RNA 함량은 배양온도가 낮아질수록 높은 값을 보여 $24^{\circ}C$에서 12.7%로 나타났다. 한편, autolysis 효율 측면에서 균체 생육속도가 증가할수록 효모 extract의 추출율은 감소하였고, 효모 extract의 분해율은 증가하는 경향을 보였으나, 배양온도는 효모 autolysis 효율에 큰 영향을 미치지 않았다.

• 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.