• Journal of the Korean Society of Marine Environment & Safety
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• v.3 no.1
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• pp.99-109
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• 1997

The in situ observations and the seawater analyses were conducted in July and August, 1996 for the purpose of describing the characteristics of organic pollution, dissolved oxygen distributions, and the evaluation of water quality in Mokpo harbour. The vertical density distribution of water column was found to be in stable structure with higher water temperature and lower salinity on surface layer at ebb tide in summer. In July, dissolved oxygen was shown to be oversaturated on surface and bottom layers, while in August, which was shown to be oversaturated on surface layer, and to be unsaturated on bottom layer as 68∼93% of saturation percentage. Dissolved oxygen of bottom layer in August was evaluated to be under the regular grades, based on Korean standards of seawater quality. In view of COD, the seawater quality of Mokpo harbour in summer was evaluated to be deteriorated due to organic wastes and graded to be the third class, and TSS of Mokpo harbour in summer was graded to be the second class, based on Korean standards of seawater quality. In particular, COD of surface layer in August was found to be under the regular grades. It is, therefore, necessary to take measures for the control of pollution loads and the proper management of seawater quality in Mokpo harbour. The distribution patterns of DO, COD, VSS and Chlorophyll-a on surface layer along the downstream center line from inner harbour to harbour entrance were similar to one another at ebb tide in August.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.348-354
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• 1992

In order to improve the productivity of invertase by recombinant Saccharomyces cerevisiae containing SUC2 gene, the effect of amino acids and dissolved oxygen concentration on the gene expression was investigated. Optimal concentrations of leucine and histidine for cell growth and cloned gene expression were 0.03 gig and 0.04 gig, respectively, expressed as the ratio of amino acid/glucose. The lack or excess of leucine and histidine has inhibitory effect on cell growth and invertase expression. In batch culture, the less aeration was, the higher invertase activity was. In continuous culture at a dilution rate of 0.09 h 1 with controlled dissolved oxygen tension, invertase activity increased dramatically at DOT levels below 5% air saturation, and a maximum activity of 215.54 KUlg cell was obtained under unaerated condition.

• Ocean and Polar Research
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• v.45 no.2
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• pp.33-42
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• 2023

Dissolved oxygen (DO) is a crucial parameter for assessing environmental conditions in aquatic ecosystems. However, commercial in situ dataloggers for oxygen optodes can be relatively expensive and limited in their specifications. In this paper, we present a novel design for a DO datalogger system based on the control boards family with RP2040 MCU chipset. Our design includes two types of dataloggers: a simple logging system and a programmable system for sampling rates via magnetic switches underwater for divers. We provide detailed descriptions of the system, including the MicroPython source code and drawings to aid in construction. We also discuss the various applications of our DO datalogger system in monitoring dissolved oxygen concentration in coastal waters and assessing the benthic metabolism of aquatic ecosystems. Our DO datalogger system provides an affordable and flexible option for researchers to accurately monitor DO concentrations in aquatic environments, and thereby improve our understanding of these complex ecosystems.

• Korean Journal of Clinical Pharmacy
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• v.22 no.3
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• pp.228-233
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• 2012

Purpose: The purpose of this study was to elucidate the effect of dissolved oxygen in alcohol to blood pressure of healthy persons. Methods: Subjects (n=30) were randomized in a double blind crossover study to receive 120 mL, 240 mL, 360 mL of alcohol (Korean spirit, 19.59 v/v%, dissolved oxygen is 8 ppm and 20 ppm). Blood alcohol concentration (BAC) and blood pressure were measured applying Lion SD-400 Alcolmeter$^{(R)}$ Breathalyser and Tensoval duo control. Pharmacokinetic parameters ($C_{max}$, $T_{max}$, $AUC_{last}$, $K_{el}$, $V_d$, Clearance) were calculated using Winnonlin$^{(R)}$ program. The difference of parameters and values were analysed by student t-test using Microsoft$^{(R)}$ Excel program. Results: The $AUC_{last}$ values of 8 ppm group and 20 ppm group in 240 ml administration were $6.15{\pm}2.60cg{\cdot}min/ml$, $5.33{\pm}1.84cg{\cdot}min/ml$ (p<0.05) and those in 360 mL were $11.93{\pm}5.70cg{\cdot}min/ml$, $10.33{\pm}4.60cg{\cdot}min/ml$ (p < 0.01), respectively. Thus, the $AUC_{last}$ was significantly decreased. On the other hands, there was a significant change in systolic blood pressure (SBP) after alcohol administration. All measured value after 360 mL of alcohol administration was significantly decreased (p < 0.01). Conclusions: The dissolved oxygen in alcoholic beverage has no effect on blood pressures but the alcohol administration has an effect on blood pressure. Thus, SBP can be used as a biomarker of alcohol administration and utilized in PK/PD modeling of alcohol.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.4
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• pp.3-12
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• 2011

Understanding of water sediment trends is an important part of water quality monitoring. Water quality variables change over time and space, and cannot be modeled or explained clearly by either temporal or spatial analysis alone. This research analysed the trends of temperature, pH levels and dissolved oxygen levels based on the sediment records and spatial data obtained in Lower Mekong Basin (LMB) during 1985-2005. Our aim is to evaluate spatio-temporal trends and graphical analyses using an Inverse Distance Weighting (IDW) interpolation method. The main results from this research can be summarized as follows. The maximum temperature and pH have been stable during the study period and the maximum dissolved oxygen has been increasing gradually until 2002. The minimum pH and dissolved oxygen have been changing in an unsteady trend during the period. A spatial analysis shows that the water temperature in this region has been increasing over time. The pH trend shows that it is decreasing during 1993-2005. Dissolved oxygen concentration has been increasing from 1989 onwards and stays in that track.

• International Journal of Fluid Machinery and Systems
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• v.5 no.1
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• pp.10-17
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• 2012

The objective of this study was to investigate the oxygen transfer characteristics of an ejector aeration system. In order to evaluate the oxygen transfer performance of the ejector aeration system, a comparative experiment was conducted on a conventional blower aeration system. The effect of entrained air flow rate and aerating water temperature on the oxygen transfer efficiency was investigated. The dissolved oxygen concentration increased with increasing entrained air flow rate, but decreased with increasing aerating water temperature for two aeration systems. The volumetric mass transfer coefficient increased with increasing entrained air flow rate and with increasing aerating water temperature for both aeration systems. The average mass transfer coefficient for the ejector aeration system was about 20% and 42% higher than that of the blower aeration system within the experimental range of entrained air flow rates and aerating water temperatures.

• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.51-58
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• 1999

A mathematical model for a three phase fluidized bed bioreactor (TFBBR) was proposed to describe oxygen utilization rate, biomass concentration and the removal efficiency of Chemical Oxygen Demand (COD) in wastewater treatment. The model consisted of the biofilm model to describe the oxygen uptake rate and the hydraulic model to describe flow characteristics to cause the oxygen distribution in the reactor. The biofilm model represented the oxygen uptake rate by individual bioparticle and the hydrodynamics of fluids presented an axial dispersion flow with back mixing in the liquid phase and a plug flow in the gas phase. The difference of setting velocity along the column height due to the distributions of size and number of bioparticle was considered. The proposed model was able to predict the biomass concentration and the dissolved oxygen concentration along the column height. The removal efficiency of COD was calculated based on the oxygen consumption amounts that were obtained from the dissolved oxygen concentration. The predicted oxygen concentration by the proposed model agreed reasonably well with experimental measurement in a TFBBR. The effects of various operating parameters on the oxygen concentration were simulated based on the proposed model. The media size and media density affected the performance of a TFBBR. The dissolved oxygen concentration was significantly affected by the superficial liquid velocity but the removal efficiency of COD was significantly affected by the superficial gas velocity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.2
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• pp.110-114
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• 2000

Effects of the combinations of six oxygen concentrations ($control, 0.6, 1.0, 2.0, 3.4 and 7.4 mg DO/l$) and two salinity levels ($20{\%_{\circ}} and 32{\%_{\circ}}$) on the rates of oxygen consumption, ammonia excretion and mortality of the mysid, Neomysis awatschensis were tested at $20{\circ}C$. The lethal level ($96 hr-LC-(50)$) of dissolved oxygen for mysid at $20{\%_{\circ}} and 32{\%_{\circ}} were 2,20 mg DO/l and 1.60 mg DO/l$ respectively, and all mysids died within $24hr at 0.6 mg DO/l$. Oxygen consumption rate of mysid was increased with dissolved oxygen increase at $20{\%_{\circ}} and 32{\%_{\circ}}$, but ammonia excretion rate was high af $1.0 mg DO/l$ during 96h exposure to DO concentration, and significantly greater in $20{\%_{\circ}} than 32{\%_{\circ}}$. $O:N$ ratio of mysid exposed during 96hr with salinity anil dissolved oxygen was below $10 at 20{\%_{\circ}} and 1,0{\~}2.0 mg DO/l, and was 4.4 at 32{\%_{\circ}} and 1.0 mg DO/l$. These results indicated that mysids were capable of changing their energy substrate in response to salinity and DO changes, and obtaining energy from proteins.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.844-851
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• 2010

Controlling the dissolved oxygen (DO) in the fed-batch culture of the medicinal mushroom Ganoderma lucidum led to a 2-fold increase of the maximum biomass productivity compared with uncontrolled DO conditions. By contrast, extracellular polysaccharide (EPS) production was two times higher under oxygen limitation (uncontrolled DO) than under increased oxygen availability (controlled DO). Morphologically, dispersed mycelium was predominant under controlled DO conditions, with highly branched hyphae, consistent with the enhanced culture growth noted under these conditions, whereas in the uncontrolled DO process mycelial clumps were the most common morphology throughout the culture. However, in both cultures, clamp connections were found. This is an exciting new finding, which widens the applicability of this basidiomycete in submerged fermentation. In rheological terms, broths demonstrated shear-thinning behavior with a yield stress under both DO conditions. The flow curves were best described by the Herschel-Bulkley model: flow index down to 0.6 and consistency coefficient up to 0.2 and 0.6 Pa $s^n$ in uncontrolled and controlled cultures DO, respectively. The pseudoplastic behavior was entirely due to the fungal biomass, and not to the presence of EPS (rheological analysis of the filtered broth showed Newtonian behavior). It is clear from this study that dissolved oxygen tension is a critical process parameter that distinctly influences G. lucidum morphology and rheology, affecting the overall performance of the process. This study contributes to an improved understanding of the process physiology of submerged fermentation of G. lucidum.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.117-120
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• 1993

This experiment was conducted to elucidate the characteristics of dissolved oxygen uptake and germination of California rice varieties, L-202(Long grain), M-202(Medium grain), S-201(Short grain), Italiconaverneco(Long grain) and Korean variety, Hwaseongbyeo under $25^{\circ}C$ water condition. The distilled water was saturated with oxygen by using air pump for 2 hours. Dissolved oxygen uptake of rice seed was measured everyday by using the oxygen electrode during 4 days from soaking to coleoptile and radicle appearance. Total dissolved oxygen uptake was 211.7${\mu}g$ per grain in Italiconaverneco during that period 179.5${\mu}g$ in S-201, 144.3${\mu}g$ in Hwaseongbyeo, 140.4 in L-202, 135.8$\mu\textrm{g}$ in M-202. The ratio of coleoptile and radicle appearance showed the highest value in Italiconaverneco, and next were S-201 and L-202. The coleoptile and radicle showed the longest length in Italiconaverneco, and next were S-201 and Hwaseongbyeo.