• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
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• pp.51-56
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• 2001

An experiment using preheated air in the coaxial diffusion flame burner was carried out in order to decrease NOx emission and improve the thermal efficiency. Preheated air combustion generally produces high NOx emissions but it was known very well to reduce NOx emission by diluting the combustion air with inert gas in preheated air combustion. In our study, $N_2$ gas was used for diluent and propane was utilized for fuel. We set the combustion air temperature on 300K, 500K, 700K, 900K and dilution level from 21% to 10% in terms of oxygen concentration. NOx emission increased along increment of combustion air temperature and decreased along increment of dilution level(lowering of oxygen concentration in combustion air). Flame-off limit with dilution level enhanced, flame length became longer and the location of maximum flame temperature became lower with increasing of combustion air temperature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.112-117
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• 2001

An experiment using high preheated and swirled air in the coaxial diffusion flame burner was carried out in order to decrease NOx emission and improve the thermal efficiency. $N_2$ gas was used for diluent and propane was utilized for fuel. Combustion using high preheated air has two remarkable characteristics ; (1) low NOx emission with increasing dilution level, (2) high thermal efficiency in the furnace. Also, swirled air can mix fuel and oxidizer well in condition of diffusion flme and maintain the stable combustion. The color of flame changes from yellow to blue green according to increasing the dilution level of mixture gas. NO emission decreased with increasing dilution level and the swirl number.

• Restorative Dentistry and Endodontics
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• 제28권5호
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• pp.425-430
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• 2003

The purpose of this study was to evaluate the clinical applications of the Sodium Dichloroisocyanurate effervescent tablet as a routine root canal irrigant by performing several in vitro tests such as $Cl^{-}$ content. cytotoxicity. antimicrobial effect as well as its pH level compared to the equivalent concentration of sodium hypochlorite solution. 1. Sodium Dichloroisocyanurate demonstrated lower level of $Cl^{-}$ concentration than each dilution of sodium hypochlorite solution. Both solution has increased level of $Cl^{-}$ as the concentration of each solution increased. There was no significant change of $Cl^{-}$ concentration in sodium hypochlorite as time goes by. However. $Cl^{-}$ concentration in Sodium Dichloroisocyanurate was increased. 2. The antimicrobial effects of both solutions were increased when their concentrations were increased. One day after dilution. antimicrobial effect of Sodium Dichloroisocyanurate was slightly higher than sodium hypochlorite. however. there was no difference in 1 week dilution solution. One month dilution solution of sodium hypochlorite still retain its activity. but antimicrobial effect of Sodium Dichloroisocyanurate was drastically decreased 1 month after dilution. 3. The cytotoxicity of Sodium Dichloroisocyanurate was rather higher than same concentration of sodium hypochlorite solution until 1 week after dilution. Then in 1 month. cytotoxicity of Sodium Dichloroisocyanurate was decreased than that of 1 week dilution solution. especially 4% Sodium Dichloroisocyanurate solution has almost no toxicity. However. 1% and 2% sodium hypochlorite solution has unchanged moderate degree of cytotoxicity after the dilution. Furthermore. 4% sodium hypochlorite solution showed high level of toxicity. 4. The pH level of Sodium Dichloroisocyanurate showed that the solution was weak acid (pH5). On the other hand. sodium hypochlorite was revealed as a strong alkaline solution (pH12). There was no change in pH following the dilution of each solution. As results. Sodium Dichloroisocyanurate solution fully satisfy the basic requirements as a root canal irrigation solution. However. we strongly recommend to use this solution clinically in low concentration and try to apply into the root canal within 1 week after dilution.

• Asian-Australasian Journal of Animal Sciences
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• 제3권2호
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• pp.143-148
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• 1990

An experiment was conducted to compare the traditional weigh-suckle-weigh method and the $D_2O$ dilution technique to estimate milk consumption of suckling piglets. Milk consumption of 50 individual piglets was estimated on four consecutive days by the $D_2O$ dilution method and for approximately 8 hours on both the second and fourth day by the traditional WSW method. The average milk intake of piglets estimated by the $D_2O$ dilution method was 45.0 g/hr and there were no significant differences between the four measurement period. The traditional weigh-suckle-weigh method provided a significantly lower estimate of milk consumption (36.8 g/hr). However correction for weight losses associated with milk suckling and weighing would increase the weigh-suckle-weigh estimate to a level similar to that determined by the $D_2O$ dilution method.

• Tribology and Lubricants
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• 제1권1호
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• pp.38-45
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• 1985

Ferrography 방법은 유체중 마모입자를 Substrate glass 위에 Van der Waals 힘에 의하여 분산교착 시키므로써 윤활 Systems에서의 기계요소들의 동특성적 마모진행과정및 mechanism의 정성적및 정량적인 분석을 가능케 한다. 정성적 방법으로는 광학현미경으로부터 SEM, X-Ray Emissiom, EDAX등의 분석방법이 적용되고 있으나, 정량적으로는 마모입자의 크기별 분포함수에 따른 Variance, Kurtosis, Skewness와 같은 인자함수의 변이가 마모진행 과정과 진행될 마모형태기구의 예측인자로서 연구되고 있다. 수치적 Model로 마모진행기구를 예측할 경우 third moment의 Skewness 가 Size 및 number분포에 따라 예민하게 반응을 나타내는 결과를 보이고 있다. 이러한 정량분석을 위하여는 실험 Sample에 따라서, 즉 오염도에 따른 Sample희석이 따르는데, 이러한 Sample 희석이 정량적 분포에 미치는 영향에 관한 연구결과는 아직 없다. 따라서 본연구에는 용제희석이 정량적 마모입자 분포에 미치는 영향을 image analyser인 Quantimat 720을 이용하여 검토하였으며 전영역의 희석률에 적용될 수 있는 Standard Calibration function에 따른 수학적 model을 유도하였다.

• 한국임상수의학회지
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• 제35권2호
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• pp.39-45
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• 2018

We evaluated the effects of green tea extract (GTE) supplementation at different dilution steps on boar sperm freezing and in vitro fertilization. Sperm intracellular hydrogen peroxide ($H_2O_2$), motility, viability, acrosome integrity and morphology were determined. In addition, sperm IVF parameters (penetration and monospermy) and glutathione (GSH) levels of presumptive zygotes (PZs) were evaluated. Semen was diluted in lactose egg yolk (LEY) and cooled at $5^{\circ}C$ for 3 h (first dilution step) and then diluted in LEY with 9% glycerol and maintained at $5^{\circ}C$ for 30 min (second dilution step). Four experimental groups were compared: first and second dilution steps without GTE (control), first dilution step with GTE (Step 1), second dilution step with GTE (Step 2) and first and second dilution step with GTE (Step 1+2). The spermatozoa were frozen in nitrogen vapor. Higher sperm motility, viability and acrosome integrity after thawing were observed in Step 1, Step 2 and Step 1+2 groups compared with the control (P < 0.05). Lower $H_2O_2$ level was observed in Step 1+2 compared with control and Step 1 (P < 0.05). For IVF, matured oocytes were co-cultured with spermatozoa frozen according to the experimental groups. GSH levels of PZs were significantly higher in Step 2 and Step 1+2 than in control and Step 1 (P < 0.05) without a significant difference in IVF parameters. In conclusion, supplementation with GTE in both first and second dilution steps during the freezing process resulted in better boar sperm cryopreservation and might be beneficial for further embryo development.

• Asian-Australasian Journal of Animal Sciences
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• 제16권3호
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• pp.380-383
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• 2003

The gas dilution technique was used to evaluate the possibility of estimating the volume of gaseous phase in the rumen from its composition in sheep given rice whole crop silage (RWS) or dent corn silage (DCS) at a level of maintenance (M) or 2 M, and in the course of fasting. The rumen gas composition was determined at 2 and 7.5 h after morning feeding. Nitrogen gas was injected by using an airtight syringe into the rumen immediately after collecting the rumen gas sample as a control. Then rumen gas samples were collected at 5, 10, 20, 40 and 60 min. after injection. Dry-matter intakes were $42g/kg^{0.75}$ and $57g/kg^{0.75}$ for DCS, and $36g/kg^{0.75}$ and $59g/kg^{0.75}$ for RWS, at 1 M and 2 M levels, respectively. Animals ingested both silages about 20% less than expected at 2 M level. The rumen gas composition did not differ significantly between 2 h and 7.5 h after feeding except for $N_2$. Content of $CO_2$ in gas composition was significantly higher at 2 M level than at 1 M (p<0.05) for both RWS and DCS, whereas $CH_4$ showed no significant difference between feeding levels. At both feeding levels, $CO_2$ showed a higher (p<0.05) percentage in DCS than RWS. A dilution technique by using $N_2$ injection is not appropriate for the determination of gas production in vivo, unless the rate of rumen gas turnover is considered. Changes in composition at fasting indicate that the rumen fermentation may reach the lowest level after 72 h fasting for sheep given silage as their sole diet.

• 한국방사선학회논문지
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• 제17권3호
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• pp.417-422
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• 2023

본 연구는 CT 검사 시 조영제로 기인한 화질 저하와 부작용을 감소시키기 위한 목적으로 식염수를 조영제에 일정 비율로 희석하였다. 이때 희석 정도에 따른 영상의 대조도 감소를 보상할 수 있는 DECT의 에너지 준위를 찾아 SNR, CNR, SSIM을 적용하여 비교 분석을 통해 영상 대조도 차 보상을 위한 DECT 적용의 유용성을 알아보았다. 그 결과 희석률 4(조영제) : 6(생리식염수), DECT의 에너지 준위 65 keV적용 시 조영제 원액을 사용했을 때와 가장 유사한 대조도 차가 형성되었고, 이때 SNR은 813.71±37.6, CNR은 921.87±17.1로 가장 높았으며, SSIM index가 1에 가장 유사한 0.851로 측정되었다. 본 연구결과는 향후 임상연구를 통해 검사부위별 적정 희석률과 에너지 레벨을 찾는 데 있어 기초정보를 제공하는 데 의미가 있으며 추가임상연구 결과를 임상에 적용한다면 조영제로 기인한 화질 저하와 부작용 문제를 줄여줄 수 있을 것으로 사료된다.

• 한국산림과학회지
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• 제97권1호
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• pp.35-44
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• 2008

목초액의 첨가가 고체 및 액체배지에서의 표고 균사생장에 미치는 영향을 조사한 결과, 고체배지에서는 첨가한 목초액의 종류와 표고 균주들간에 다소 차이가 있었는데, 전통식 목초액은 대체로 희석농도 500배 이하에서 균사생장을 억제하였고 1000~2000배에서는 균사생장을 촉진하였으나 기계식 목초액의 경우는 대체로 1000배 이하에서 균사생장을 억제하였고 2000배에서는 촉진하였다. 액체배지의 경우에는 전통식, 기계식 목초액 모두 희석농도 2000배에서 균사생장을 촉진하였고 500배 농도에서 억제하였다. 목초액을 농도별로 첨가한 배지에서 배양한 표고 균주를 참나무 원목에 접종하였을 경우, 산조302호는 2000배, 산림2호 및 3호는 4000배의 희석농도 배지에서 배양한 균주가 목재부후력과 침투력에서 우수하였고, 목재부후력과 침투력의 정도는 비례하였다. 목초액의 처리가 표고재배시 문제가 되는 병원성 균주에 미치는 영향을 비교한 결과, 전통식 목초액은 50배 희석농도에서 푸른곰팡이 균주의 생장을 모두 억제하였고, 기계식 목초액은 균주에 따라 50배~500배 이하에서 균사생장을 억제하였다. 주홍꼬리버섯에 대하여 전통식 목초액은 500배 이하에서 균사생장을 억제하였고, 기계식 목초액은 500배 이하에서 억제하였으며 100배 희석농도에서 80%, 50배에서 100% 억제하였다. 골목의 목초액 농도별 침수처리에 의한 표고 자실체의 생중량 및 건중량은 모든 처리에서 무처리에 비하여 유의적 증가를 보였으나 특히 250배 희석농도에서 가장 효과가 우수하였다. 목초액을 희석 농도별로 처리하여 생산한 버섯을 $10^{\circ}C$에서 10일간 저장한 후에 조직분석기(Texture analyzer)를 사용하여 전단력을 측정한 결과, 250배 희석농도 처리에 의하여 생산된 버섯이 조직감이 가장 우수하였다. 저장 전후의 버섯함수율은 희석농도별로 유의적 변화가 없었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.349-352
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• 2008

This study has numerically modeled the combustion processes of the turbulent swirling premixed lifted syngas flames in the low-swirl burner (LSB). In these turbulent swirling premixed flames, the four tangentially-injected air jets induce the turbulent swirling flow which plays the crucial role of stabilizing the turbulent lifted flames. In the present approach, the turbulence-chemistry interaction is represented by the level-set based flamelet model. Numerical results indicate clearly that the present level-set based flamelet approach has realistically simulated the structure and stabilization mechanism of the turbulent swirling premixed lifted flames in the low-swirl burner. Computations are made for the wide range of the syngas chemical composition and the dilution level at two pressure conditions (1.0, 5.0 bar). Numerical results indicate that the lifted height in the LSB is increased by decreasing the H2 percentage and increasing the dilution level at the given equivalence ratio. It is also found that the flashback is occurred for the hydrogen composition higher than 80% at the equivalence ratio, 0.8. However, at the syngas composition range in the IGCC system, the stable lean-premixed lifted flames are formed at the low-swirl burner.