• Environmental Engineering Research
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• v.12 no.4
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• pp.148-154
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• 2007

The purpose of this research was to investigate the effects of low concentration of oxygen on reduction of perchlorate, especially low perchlorate influent concentrations in a biofilm reactor, as well as the effect of flow pattern in a biofilm reactor. Dissolved oxygen averaging 1 mg/L did not inhibit reduction of influent perchlorate from 23 to $426\;{\mu}g/L$ in the biofilm reactors when sufficient acetate was added, probably due to limitation of oxygen diffusion into the biofilm. Influent perchlorate ranging from 23 to $426\;{\mu}g/L$ was reduced to below detection level ($4\;{\mu}g/L$) in the presence of 1 mg/L dissolved oxygen (DO). Chloride was produced in a ratio of $0.37gCl^-/g{ClO_4}^-$ and $0.35gCl^-/g{ClO_4}^-$ in plug flow and recirculation biofilm reactor which is similar to stoichiometric amount ($0.36gCl^-/g{ClO_4}^-$) indicating complete perchlorate reduction at $426\;{\mu}g/L$ of ${ClO_4}^-$ feeding. At $23\;{\mu}g/L$L influent perchlorate, total biomass solids were 3.18 g and 2.81 g in the plug flow and recirculation biofilm reactors. The most probable number(MPN) analysis for perchlorate-reducing bacteria showed $10^4$ to $10^5\;cells/cm^2$ in both biofilm reactors throughout the experiments. The effluent perchlorate concentrations were not significantly different in the two different flow regimes, plug flow and recirculation biofilm reactors.

• The Journal of the Petrological Society of Korea
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• v.4 no.2
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• pp.124-133
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• 1995

Oxygen isotope compositions have been determined for the granitic and the related rocks from the Wolf River Ratholith, Wisconsin in U.S.A. Plutons which belong to the differentiation trend are almost identical in oxygen isotope fractionation, and plutons of undifferential sequences also show oxygen isotope compositions similar to each other, which show little isotope fractionations at high temperature range. In oxygen osotope composition, the country rocks (the Penokean plutonic rocks), which is higher by 1~2 permil than the batholith are improbable source of the batholith. However, the assimilation of parent magma of lower ${\delta}^{18}O$ values than the batholith with the Penokean plutonic rocks might have produced the batholith.

• The Korean Journal of Malacology
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• v.31 no.1
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• pp.43-48
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• 2015

Oxygen isotope ratios (${\delta}^{18}O$) of three Pacific oyster (Crassostrea gigas) specimens from the Neolithic Yeondae-do shell midden site, Tongyeong, Korea, were analyzed to determine the seasonality of shellfish gathering and site occupation. Oxygen isotope samples were taken from the left valve hinge sections of the specimens. Oxygen isotope values ranged between -0.1 ‰ and -2.4 ‰, between -0.2 ‰ and -2.9 ‰, and between 0.3 ‰ and -2.8 ‰ in oyster specimen #one, #two and #three, respectively. The isotope profiles showed seasonal temperature cycles, providing information related to the seasonality of shellfish gathering and site occupation. Hinge-edge oxygen isotope values of the specimens showed decreasing trends after passing through maximum values (winter), indicating that they formed during spring. Thus it can be assumed that during spring season, oysters were gathered and the site was occupied.

• Journal of The Korean Society of Clinical Toxicology
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• v.11 no.2
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• pp.81-88
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• 2013

Purpose: The aim of this study is to investigate current status, indications, and complications of hyperbaric oxygen therapy. Methods: A retrospective investigation of patients who underwent hyperbaric oxygen therapy at a university medical center from September 2004 to August 2013 was conducted based on patients' medical records and results of an email survey for 99 emergency centers. Results: During the study period, a total of 233 patients underwent hyperbaric oxygen therapy. Indications for hyperbaric oxygen treatment of illness or injury were as follows: 1) 151 cases of acute carbon monoxide poisoning(65.4%), 2) flap wound management, including 42 cases(18.2%), 3) skin care transplanted, including 23 cases(10.4%), 4) Burger's disease, including 5 five cases(2.1%), respectively. Total application time$^*$ frequency was 1,088 and total time was 1,239 hours. Among 233 patients who underwent hyperbaric oxygen therapy, 32 patients(13.7%) had complications: 1) otalgia in 21 cases(9.0%), 2) mastoiditis?in six cases(2.6%), 3) hemotympanum in five cases(2.1%), respectively. There were only 8 emergency centers that currently had an operational hyperbaric oxygen chamber in 77 emergency centers(10.4%). Conclusion: Indications identified through this study showed difference from current indications worldwide. It seems necessary that physicians' perception regarding application of hyperbaric oxygen therapy for more indications be changed and improved. A hyperbaric chamber capable of providing respiratory assistance and intensive care is also needed. A good network for sharing treatment experiences and a specialized team for administration of hyperbaric oxygen therapy is also required.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.243-244
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• 2014

The opposed flow flame in a mesoscale channel was constructed to observe the flame stabilization behaviors at low strain rate conditions (<$10s^{-1}$). The purpose of this study is to get the overall flame behaviors of partially premixed flames with oxygen enhanced conditions at low strain rates. The oxygen ratio in oxidizer was changed from 18 to 30 %. Conclusively, the flame extinction limit approached to about $1s^{-1}$, and divided into three representative regimes corresponding to self propagating flame, transitional flame, quenching flame regimes.

• Journal of environmental and Sanitary engineering
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• v.15 no.1
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• pp.7-13
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• 2000

To develop the removal technique of algal bloom the efficiencies of algal flocculation/ autoflotation by the kinds of coagulant and oversaturated oxygen concentration were investigated. The summarized results are as follow. 1. In the algae flocculation test with alum[$Al_2(SO_4)_3{\cdot}18H_2O$], optimum pH was 5.5 and, with chitosan optimum pH was 7.0. 2. Chitosan which was natural polymer showed the 5~10 times higher algal biomass flocculation efficiency than alum in the condition of same algal concentration. 3. For the each coagulant, the higher ${\Delta}DO$(oversaturated dissolved oxygen concentration - saturated dissolved oxygen) was, the faster the rising velocity of the algal floc was. 4. In the condition of about 4mg/L ${\Delta}DO$, the rising velocity of chitosan is about 2 times higher than that of alum, and chitosan formed the stronger algal floc.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.4
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• pp.137-139
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• 2008

Floating zone, neutron transmutation-doped and magnetic Czochralski silicon crystals are being widely used for fabrication power devices. To improve the quality of these devices and to decrease their production cost, it is necessary to use large-diameter wafers with high and uniform resistivity. Recent developments in the crystal growth technology of Czochralski silicon have enable to produce Czochralski silicon wafers with sufficient resistivity and with well-controlled, suitable concentration of oxygen. In addition, using Czoehralski silicon for substrate materials may offer economical benefits, First, Czoehralski silicon wafers might be cheaper than standard floating zone silicon wafers, Second, Czoehralski wafers are available up to diameter of 300 mm. Thus, very large area devices could be manufactured, which would entail significant saving in the costs, In this work, the conventional Czochralski silicon crystals were grown with higher oxygen concentrations using high pure polysilicon crystals. The silicon wafers were annealed by several steps in order to obtain saturated oxygen precipitation. In those wafers high resistivity over $5,000{\Omega}$ cm is kept even after thermal donor formation annealing.

• Journal of the Korean Ceramic Society
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• v.18 no.1
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• pp.23-26
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• 1981

The electrical conductivity of highly pure polycrystalline $Yb_2O_3$ has been measured from 650 to 105$0^{\circ}C$ under oxygen pressure range of $10^{-5}$ to 102 torr. The conductivity dependence of oxygen pressure in the temperature region from 750 to 105$0^{\circ}C$ is approximated by $\sigma$ $\alpha$ $Po_2^{1/5.3}$. This shows that the conduction mechanism is associated with doubly ionized metal vacancies. Fairly low activation energy and the lack of oxygen pressure dependence are found over the temperature range of 650 to 75$0^{\circ}C$. The conduction mechanism can be explaned by not metal vacancies, but hopping oxygen ions in the oxide.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.96-99
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• 1992

The microanalysics by the direct observation of 180 (P, a)'" nuclear reactions on tungsten (110) surfaceare investigated using a 2MeV Van de Graaff accelerator. This method allows the determination of very smallquantities of nuclei near the surface of samples. The yields increase with oxygen exposure. The oxygen coverage, 0, is 0.5 at 5 Langmuir and 1.0 at 15 Langmuir.5 Langmuir.

• Archives of Craniofacial Surgery
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• v.20 no.4
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• pp.246-250
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• 2019

Recently, there is a growing interest of hyperbaric oxygen therapy in many fields of medicine. We had a 43-year-old female patient presented with severe necrosis of the nose, philtrum, and upper lip due to retrograde arterial occlusion after nasolabial fold hyaluronic acid filler injection. Our patient went through 43 sessions of systemic hyperbaric oxygen therapy from December 2, 2017 to January 18, 2018. We administered 2.8 atmosphere absolute (ATA) for 135 minutes in the first session and the remaining sessions consisted of 2.0 ATA for 110 minutes. In reporting this case, we wish to provide a warning regarding the latent risk of filler injections and share our experience about minimizing soft tissue damage in the early stages with systemic hyperbaric oxygen therapy.