• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.20
• /
• pp.69-73
• /
• 1975

Jinheung rice seeds ranging from 5.6 to 14.7 percent of water content were X-irradiated from 1.5 to 25 kR in vacuum and then immediately hydrated in either oxygen- or nitrogen-bubbled water at around 19$^{\circ}C$ for 12 hours. Results, as reported in terms of reduction of $M_1$ seedling height and survival, sterility and $M_2$ mutation frequency, indicate that the post-irradiation oxygen effect in very dry seeds was conspicuous; the seedling height and the survival were drastically reduced, and the sterility and the mutation frequency were increased in super dry seeds.

• Explosives and Blasting
• /
• v.21 no.1
• /
• pp.85-94
• /
• 2003

발파후에 2차연소 또는 폭발(이하, 2차연소라 한다. )이 일어났다는 사실은 폭약이 폭발후에 어떤 가연성가스가 발생하고 그 가연성가스가 잔존하는 폭발열 또는 기타의 점화원에 의해 연소되었음을 의미한다. 폭약이 폭발하였을 때, 발생 가능한 가연성물질은 유리탄소, 일산화탄소, 수소 등으로 추정할 수 있는데 실험결과에서는 가연성물질의 주성분이 수소인 것으로 나타났다. 본 연구에서는 에멀존계 함수폭약이 산소평형, 알루미늄함량, 알루미늄형태와 크기 그리고 포장지의 두께에 따라 수소가 발생되는 양을 가스크로마토그라피를 이용하여 측정하였다. 상기의 열거한 요인들은 모두 수소발생량과 관계가 있는데, 이중에서도 가장 중요한 요인은 산소평형과 알루미늄의 함량인 것으로 나타났다. 한 예로 알루미늄이 15%가 포함되고 산소평형이 -10인 에멀존계 함수폭약은 폭발후에 19.4%의 수소를 함유하고 있는 후가스를 발생시켰으며 이 가스를 포집하여 공기중에 방출시키면서 성냥불을 가까이 하였더니 연소가 되었다. 따라서 에너지를 높이기 위하여 알루미늄의 함량을 높이고 산소평형을 지나치게 마이너스로 설계한다면, 2차연소는 언제든지 발생할 가능성이 있다고 판단된다. 알루미늄의 함량을 가능한 적게, 산소평형을 가능한 0에 가깝게 설계해야 만이 2차연소 현상을 방지할 수 있을 것이며 ㄸ한 최적의 설계뿐만이 아니라 정확한 제조와 품질검사도 2차연소 현상을 방지하는데 중요한 몫을 할 것으로 판단된다.

• Journal of Energy Engineering
• /
• v.25 no.4
• /
• pp.159-169
• /
• 2016

In this study, the effects of MTBE contents as oxygenates in gasoline on exhaust emissions and fuel economy in MPI and GDi vehicles have been investigated. Various oxygen contents have been selected such as 0, 1.0, 2.3 and 2.7 wt%. FTP-75 and HWFET modes as fuel economy test methods which are widely used in Republic of Korea and US were applied to investigate exhaust emissions from the test vehicles. Emissions of CO, NMHC and NOx did not show significant correlation with oxygen contents in gasoline fuels, although having slight difference with these contents. In addition, CO2 emissions were not significantly changed with respect to oxygen content. But in case of warm-up and FTP-75 and HWFET modes including high speed regimes, CO2 emissions showed inverse correlation with oxygen contents. Particulate number concentration was inversely proportional to the oxygen contents, having the minimum value at the condition of 2.3 wt%. In case of fuel economy through carbon balance method, the highest value has been obtained at 2.3 wt% and there was positive correlation with oxygen contents and fuel economy.

• Journal of Ginseng Research
• /
• v.23 no.1 s.53
• /
• pp.44-49
• /
• 1999

Cu/Zn superoxide dismutase (SOD1) is a protective enzyme responsible for the dismutat ion of superoxide radicals within the cell by converting superoxide radicals to oxygen and hydrogen peroxide, which is in turn changed to oxygen and water by catalase. Previously, we reported that the panaxadiol (PD) and its ginsenoside $Rb_2$ induced the expression of SOD1 gene through AP2 binding site and its induction. Here, we examined the effect of subfractions of panaxadiol ginsenosides, which were extracted from different parts of ginseng root that possess various ratios of panaxadiol to panaxatriol, on the induction of SOD1 gene expression. To explore this possibility, the upstream regulatory region of SOD1 was linked to the chloramphenicol acetyl transferase (CAT) structural gene and introduced into human hepatoma HepG2 cells. We observed that the transcriptional activation of SOD1 was proportional to the contents ratio of panaxadiol ginsensides. Consistent with this results, the total extract portion prepared from the finely-hairy root, which contains the higher ratio of panaxadiol to panaxatriol about 2.6, increased the SODl transcription about 3 fold. This results suggest that the panaxadiol fraction could induce the SOD1 and total extract of the ginseng finely-hairy root would be a useful material as a functional food for the SOD1 inducer.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2001.09a
• /
• pp.57-60
• /
• 2001

미생물 활성도와 그에 따른 유기물의 분해율은 미생물의 호흡률과 직접적인 관계가 있다. 본 연구는 매립종료후 경과기간이 1년인 Y 매립지와 10년인 C 매립지의 오염특성을 조사하였고, 오염토양 미생물의 산소소비속도를 이용하여 매립종료기간에 따른 오염토양의 산소소비율을 비교 평가 하고자 하였다. C 매립지의 오염토양에 대한 SCO $D_{cr}$ TOC는 Y 매립지에 비해 낮은 함량으로 나타났으나 T-N, N $H_3$-N의 함량은 큰 차이를 보이지 않았다. TOC/T-N비로 보았을 때 Y 매립지에 비해 C 매립지가 낮은 것으로 나타나 연령이 많은 경우 분해성 유기물의 함량은 적은 것으로 판단된다. 산소소비율 실험결과 Y 매립지가 산소소비율이 높은 것으로 나타났으며, C 매립지도 대조토양에 비해 높은 산소소비율을 보였다. 따라서 매립종료 후 경과기간이 10년인 매립지의 미생물의 산소소비율을 보았을 때 여전히 생물학적 안정화가 종료되지 않은 것을 알 수 있었다.

• Journal of the Korean Society of Safety
• /
• v.8 no.3
• /
• pp.83-90
• /
• 1993

직류 아아크 용접시 아아크 프라스마와 용융 금속 사이의 계면에서 일어나는 전기 화학 반응이 용착금속 내의 산소와 질소의 함량에 미치는 영향이 고찰되었다. 열 화학 반응 뿐만 아니라 전기 화학 반응도 용접부의 산소 및 질소의 함량을 결정하는 중요한 반응 메카니즘이라는 것과 전기 화학 반응의 양을 결정하는 것은 단위 면적당 통과하는 전류의 양을 조절하는 용접 전류와 용접 속도라는 것이 실험적으로 입증되었다. 따라서 이 연구 결과는 아아크 용접시 적당한 용접 조건의 선택뿐만 아니라 용접 재료의 설계 또는 선택에 중요한 지침을 준다.

• Applied Chemistry for Engineering
• /
• v.33 no.1
• /
• pp.38-43
• /
• 2022

The effect of introducing oxygen functional groups by oxygen plasma treatment of activated carbon on adsorption properties of cesium ions was investigated. During the oxygen plasma treatment, the frequency, power, and oxygen gas flow rates were fixed at 100 kHz, 80 W, and 60 sccm, respectively, while the reaction time was varied. Under the experimental conditions, the amount of cesium ion adsorption increased as the content of oxygen groups on C-O-C and O=C-O bonds increased when the reaction time with oxygen gas was 10 minutes. However, when the reaction time increased to 15 minutes, the oxygen functional group content decreased resulting in the decrease of the adsorbed cesium ion amount. On the other hand, unlike the oxygen content of the surface-treated activated carbon, the specific surface area and pore properties were hardly affected by the oxygen plasma reaction time. As a result, the oxygen plasma-treated activated carbon improved the cesium ion removal rate by up to 97.3% compared to that of the untreated activated carbon. This is considered to be due to the content of oxygen groups on C-O-C and O=C-O bonds introduced on the surface of the activated carbon through oxygen plasma treatment.

• Journal of the Korean Magnetics Society
• /
• v.3 no.3
• /
• pp.229-233
• /
• 1993

The effects of differential partial pressures of oxygen during sputtering on the magnetic and recording characteristics of magneto-optical disks were investigated. Different flows of oxygen were deliberately introduced into the sputtering chamber to have a variety of partial pressures of oxygen during sputtering. A residual gas analyzer was employed to monitor the oxygen peak before, during, and after sputtering and to estimate the reacted oxygen amount. Most of the oxygen introduced into the chamaber was reacted during sputtering. As the partial pressure of oxygen increased, the oxygen content of the TbFeCoCr film increased also. The oxygen appeared to be bound as Tb-O, effectively decreasing the magnetically active Tb content of the film The coercivity decreased but the squareness of the Kerr hysteresis loops was still excellent. The perpendicular anisotropy was not significantly affected by oxygen amount. The carrier-to-noise ratio, includi!1g the write power sensitivity and bias field sensitivity did not change too much with oxygen content in the film The disks sputtered with oxygen showed better bias field sensitivity with lower write power threshold than the disk sputtered without oxygen, due to high demagnetization during domain formation. No significant degradation of coercivity for the disk sputtered oxygen was observed during an accelerated aging test.

• Applied Chemistry for Engineering
• /
• v.25 no.3
• /
• pp.324-329
• /
• 2014

Microalgae Nannochloropsis oculata (N. oculta) and Chlorella vulgaris (C. vulgaris) are important sources for biodisel because of the high content of neutral lipids. Stable nano bubble is maintained for a long time and therefore it is possible for use in biotechnology. In this study, effects of nano bubble oxygen or hydrogen water on the microalgae growth were characterized. The cell growth in nano bubble water was similar to that of control, and the total lipid content was rather low. But, chlorophyll content of N. oculata grown in nanno bubble oxygen and hydrogen water increased 54% and 30%, and increased 59%, 39% in C. vulgaris. Carotenoid content also increased 21%, 25% in N. oculata and 49%, 29% in C. vulgaris grown in nano bubble oxygen and hydrogen water. From these results, nano bubble water seems to enhance the photosynthetic capacity of microalgae.

• Journal of Applied Biological Chemistry
• /
• v.61 no.1
• /
• pp.25-31
• /
• 2018

This study investigated the effect of different $O_2$ transmission rate (OTR) of films on surface temperature, weight loss, pH, $O_2$, $CO_2$ and sensory characteristics, microbial quality, total phenolic contents and 1,1-diphenyl-2-picryl hydrazyl radical scavenging activity of fresh-cut lettuce during storage at $10^{\circ}C$ for 7 days. $80{\pm}5g$ of fresh-cut lettuce were packaged with oriented polypropylene films respectively. The OTR of packaging materials was 5,000, 8,000 and $10,000cc/m^2{\cdot}day{\cdot}atm$. Quality characteristics showed significant differences during storage. The surface temperature was averaged 13 and lower in higher OTR of films. The weight loss of lettuce ranged from 2.8 to 5.4% and the highest loss showed in $5,000cc/m^2{\cdot}day{\cdot}atm$ of film. pH was increased during storage and the highest pH was found in $5,000cc/m^2{\cdot}day{\cdot}atm$. The $O_2$ content in the packaging was decreased with increasing $CO_2$ content during storage. The lowest $CO_2$ was found in $10,000cc/m^2{\cdot}day{\cdot}atm$. As OTR was decreased, antioxidant profile of lettuce was decreased. Total aerobic bacteria showed from 5.48 to 6.59 log CFU/g. From the result of the overall sensory test, the marketability of fresh-cut lettuce stored at $10^{\circ}C$ seemed to be maintained effectively over 5 days.