• 한국식품영양학회지
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• 제7권4호
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• pp.399-405
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• 1994

Some method was introduced to explain oxygen transfer from broth to cell during aerobic microbe cultivation. It is explained by 5 steps that how desolved oxygen can reach to cell. Among these steps film resistance was the most important factor to describe oxygen transfer. Lumped model and distributed model was introduced to explain oxygen diffusion rate and oxygen consumption rate which occurs in the microbe pellet.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2221-2228
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• 2021

One-dimensional oxygen transport relation is indispensable to study the oxygen distribution in the LBE-cooled system with an oxygen control device. In this paper, a numerical research is carried out to study the oxygen transport characteristics in a gas-phase oxygen control device, including the static case and dynamic case. The model of static oxygen control is based on the two-phase VOF model and the results agree well with the theoretical expectation. The model of dynamic oxygen control is simplified and the gas-liquid interface is treated as a free surface boundary with a constant oxygen concentration. The influences of the inlet and interface oxygen concentration, mass flow rate, temperature, and the inlet pipe location on the mass transfer characteristics are discussed. Based on the results, an oxygen mass transport relation considering the temperature dependence and velocity dependence separately is obtained. The relation can be used in a one-dimensional system analysis code to predict the oxygen provided by the oxygen control device, which is an important part of the integral oxygen mass transfer models.

• 한국환경과학회지
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• 제8권3호
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• pp.349-354
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• 1999

The transfer function was introduced to establish the prediction method for the DO concentration at the intaking point of Kongju Water Works System. In the mose cases we analyze a single time series without explicitly using information contained in the related time series. In many forecasting situations, other events will systematically influence the series to be forecasted(the dependent variables), and therefore, there is need to go beyond a univariate forecasting model. Thus, we must bulid a forecasting model that incorporates more than one time series and introduces explicitly the dynamic characteristics of the system. Such a model is called a multiple time series model or transfer function model. The purpose of this study is to develop the stochastic stream water quality model for the intaking station of Kongju city waterworks in Keum river system. The performance of the multiplicative ARIMA model and the transfer function noise model were examined through comparisons between the historical and generated monthly dissolved oxygen series. The result reveal that the transfer function noise model lead to the improved accuracy.

• 한국미생물·생명공학회지
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• 제10권3호
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• pp.223-226
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• 1982

통기발효에서 중요한 통기 및 진탕효과를 측정함에 있어 공기로부터 물속으로 용존해 가는 산소의 전달속도와, 용존된 산소가 미생물에 의해 흡수되는 속도를 산출하였다. 항생물질발효에서 통기효과는 현저하였으며, 배양시간에 따른 산소흡수 속도와 비산소흡수 속도가 변화하는 것을 알았다. 이러한 변화는 대사이차 산물인 항생물질생합성의 생화학적인 전환에 기인하는 것으로 판단된다.

• 한국물환경학회지
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• 제25권6호
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• pp.896-901
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• 2009

In this study, in order to apply the air and pure oxygen in the Jet Loop Reactor (JLB) in which the oxygen transfer rate is high, differentiate the operation mode according to each air flowrate and liquid flowrate and investigate the oxygen transfer characteristic, an experiment was carried out. The oxygen concentration with the air flowrate ($Q_g$) and liquid flowrate ($Q_L$) was identical but the oxygen transfer coefficient ($K_L{\cdot}a$) is linear depending on degree of two factors. The width of an increase is small in $0.1min^{-1}$ when the air flowrate is 0.2 L/min with increasing the liquid flowrate. Whereas, the increment was exposed to be very high for $1.5min^{-1}$ when the air flowrate was 5 L/min. In the experiments using the pure oxygen, it was 30 mg/L of oxygen concentration finally and it was 3.5 times than using the air. But the time reached the saturated concentration was similar to using the air, and $K_L{\cdot}a$ was similar to using the air too. Analysis between two independent variable and oxygen transfer of the correlation is the same model like $K_L{\cdot}a={0.0161Q_L}^{1.5371}{Q_g}^{0.5433}$ using with coefficient non linear regression analysis. It was resulted that the liquid flowrate were approximately three times than air flowrate on effect to oxygen transfer rate.

• 상하수도학회지
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• 제32권5호
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• pp.381-388
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• 2018

Microbubbles oxygen transfer to water was simulated based on experimental results obtained from the bubbles generation operated under varying liquid supply velocity to the multi-step orifices of the generator. It had been known that liquid supply velocity and bubble size are inversely related. In the oxygen transfer, a non-steady state was assumed and the pseudo stagnation caused the slow movement of bubbles from the bottom to the water surface. Two parameters were considered for the simulation: They represent a factor to correct the pseudo stagnation state and a scale which represented the amount of bubbles in supply versus time. The sum of absolute error determined by fitting regression to the experimental results was comparable to that of the American Society of Civil Engineers (ASCE) model, which is based on concentration differential as the driving force. Hence, considering the bubbles formation factors, the simulation process has the potential to be easily used for applications by introducing two parameters in the assumptions. Compared with the ASCE model, the simulation method reproduced the experimental results well by detailed conditions.

• 조명전기설비학회논문지
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• 제14권6호
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• pp.58-68
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• 2000

본 논문에서는 다대식 가열로내의 산소 농도 변화를 표현하는 모델이 제안되었다. 설계된 모델은 크게 '잔류 가스에 대한 모델'과 '산소에 대한 모델'의 두가지로 구성되었다. 각각의 모델은 산소농의 변동에 관여하는 네가지 요인들올 화학, 유체 이론적 관계식과 퍼지 이론을 이용하여 설계되었다. 고려된 네가지 요인들은 버너에서 의 연소반응, 연소대간의 유체 이동, 가열로 내부로부터 외부로의 유체 흐름 및 출입구를 통한 외부 공기의 유입 등이다. 모의 실헝 결과블 통해 제안된 모델로 계산된 각 연소대내의 산소 농도 변화가 설제 조업시 발생하는 유형과 유시함을 알 수 있었다.

• 항공우주기술
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• 제5권2호
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• pp.134-142
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• 2006

헬륨분사를 통한 극저온 추진제의 과냉각 방식은 발사체의 이륙 전에 액체산소의 bulk boiling을 억제하고 과냉각 상태를 유지하기 위한 효과적인 방법들 중의 하나이다. 본 자료에서는 이러한 헬륨 분사 냉각 시스템에 대한 이론적 고찰을 통해 열전달과 질량전달 조건을 이해하고, 해석 모델을 제시하였다. 해석 모델의 주요 특징은 유한 열전달과 무한질량전달 개념을 이용하여 분사 시스템을 표현한 것이다. 또한, 실험과 해석결과의 비교를 통하여 해석 모델을 검증하였으며, 헬륨 분사량의 변화, 탱크 압력의 변화 등 조건 변화에 따른 결과를 살펴보았다.

• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1093-1097
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• 1994

The interaction of oxygen molecule with Ni44(111) model surface to which the molecule approaches is studied by calculating the relevant DOS and COOP with the tight-binding EHT method. It is found that the dissociative adsorption of oxygen takes place as a result of electron transfer from the Ni d${\pi}$ orbital to the antibonding 1${\pi}_g$ orbital of the oxygen molecule. This finding is noteworthy to contrast with the case of Ni(100) surface in which the electron transfer takes place from the Ni d${\delta}$ orbital of the nickel surface.

• 방사성폐기물학회지
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• 제3권2호
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• pp.85-93
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• 2005

Isotopes of alkali and alkaline earth metals (AM and AEM) are the main contributors to the heat load and the radiotoxicity of spent fuel (SF) . These components are separated from the SF and dissolved in a molten LiCl in an electrolytic reduction process. A mass transfer model is developed to describe the diffusion behavior of Cs, Sr, and Ba in the SF into the molten salt. The model is an analytical solution of Fick's second law of diffusion for a cylinder which is the shape of a cathode in the electrolytic reduction process. And the model is also applied to depict the concentration profile of the oxygen ion which is produced by the electrolysis of Li$_{2}$O. The regressed diffusion coefficients of the model correlating the experimentally measured data are evaluated to be greater in the order of Ba, Cs, and Sr for the metal ions and the diffusion of the oxygen ion is slower than the metal ions which implies that different mechanisms govern the diffusion of the metal ions and the oxygen ions in a molten LiCl.