• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.56-62
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• 2001

울릉분지 남서부 해역에서 채취한 두 개의 피스톤 코어 (piston core) 시료를 이용하여 퇴적학 및 지화학적 특성을 연구하였다. 코어는 제4기말의 이질 퇴적물로 대부분 구성되어 있고, 테프라 (tephra layer)와 사질 퇴적물이 일부 협재되어 나타난다. 기존 확인된 울릉분지의 테프라를 이용하여 층서 대비를 한 결과, 두 코어는 대양보다는 높은 퇴적률 (10-12cm/kyr)을 갖는다. 이는 코어가 약 4만 4천년 전의 기록부터 시작하고 있음을 의미한다. 동위원소 층서 2 (마지막 빙기) 중에 형성된 구간에서는 저탁류의 영향을 많이 받은 여러 종류의 퇴적상들이 교호하여 나타난다. 코어의 하부 구간에서는 가스의 방출에 의하여 형성된 것으로 사료되는 수평균열이 다수 관찰된다. 두 코어에서 측정된 유기탄소 (organic carbon) 함량은 평균 $1.8\% $(0.1-4.5\%)$으로 열린 바다 (open sea) 퇴적물의 유기탄소 함량보다 높다. 이는 Termination I 시기 때 해수면 상승으로 인해 산소가 다소 결핍된 환경으로 전이되면서 유기탄소의 양이 증가하였음을 보여주는 것으로 해석된다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.133-136
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• 2002

제주도에 내리는 강수의 동위원소 조성의 시공간적인 분포를 파악하고 지하수 함양과의 관련성을 연구하기 위하여, 한라산의 남측과 북측 사면에 8개의 강수채수기를 설치하여 1년 동안 (2000. 9 ~ 2001. 8) 월강수를 채취하였다. 연구기간 동안에 강수량은 남쪽사면이 북쪽사면보다 약 37% 더 많았다. 강수의 산소동위원소 조성은 온도효과를 거의 보이지 않았다. 그러나 여름 강우에는 우량효과가 매우 뚜렷하였다. 고도가 높아지면서 강수의 동위원소 조성이 낮아지는 고도효과가 남측과 북측사면에서 모두 뚜렷이 관찰되었다. 가중평균값으로 볼 때 북측사면 강수의 동위원소 조성이 남측사면 강수보다 약 0.5$^{0}$ $_{00}$ 낮은 것이 관찰되었는데 이는 비그늘효과(rain shadow effect) 때문인 것으로 해석된다. 다른 지역에 비하여 북부지역 지하수 동위원소 조성이 상대적으로 결핍되어 있는 것은 기존 연구 결과처럼 지하수 이동속도가 빠르기 때문에 일어나는 현상이 아니고 지하수로 함양된 강수의 원래의 동위원소 조성을 반영하기 때문인 것으로 해석된다.다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.169-169
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• 2010

650nm 적외선 차단 필터를 Macleod 프로그램을 이용하여 설계하고, 이온보조증착(IAD) 장비를 이용하여 코팅한 후 투과도, 파장, 두께특성을 조사하였다. 차단필터의 증착물질은 $TiO_2$ (n=2.30) /$SiO_2$ (n=1.46) 을 사용하여 45층의 다층 박막으로 증착하였다. 코팅된 차단필터는 차단파장이 651 nm로써 평균 ${\pm}5$ nm 이내의 편차를 보였다. 420~630 nm 파장영역에서 평균 투과도는 89%이었으며, 투과도의 균일도는 약 2.12로써 매우 균일하였다. 투과도기 단파장 영역에서 감소된 것은 다층박막 증착 시 산소가 결핍된 것으로 판단된다.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.390-393
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• 2002

BTEX biodegradation in groundwater including ethanol by soil microorganisms was much slower than that without ethanol. This was caused by that the ethanol was preferentially utilized by microorganisms and oxygen and mineral in soil were depleted. When Fe(III), nitrate, sulfate were added in groundwater, the degradation of BTEX was increased and the sulfate showed best efficiency.

• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.323-332
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• 1976

The x or $x^0+x'$ values of the nonstoichiometric chemical formula $TiO_{2-x}$ or $Ti_{2-(x^0+x')}$ have been measured by a specially made magnetic quartz microbalance in a temperature range from 600 to $1300^{\circ}C$ under oxygen pressures of $1{\times}10^{-6} to 1 atm. The standard x or $x^0$ value of the rutile is 0.00148. The x values $under_xoxygen$ pressure of 1 atm decrease with temperatures and then the stoichiometric rutile (or x = 0) is formed at $1130^{\circ}C$. The x values varied between 0.00148 and 0.01719 at a temperature range from 600 to $1300^{\circ}C$ under $1{\times}10^{-9}{\sim}1{\times}10^{-2}$ atm oxygen pressures. The enthalpies of formation of the nonstoichiometric rutile, $H_f$, varied between 21.05 and 29.97 Kcal/mole under the above conditions. The 1/n values calculated from the plots of log X' vs. log $Po_2$ are -{\frac{1}{2}}{\sim}-{\frac{1}{4}} under low oxygen pressure range of $1{\times}10^{-6}\;to\;1{\times}10^{-4}$ atm. Many physical properties of the titanium dioxide, such as the stability of the rutile, Electrical conductivity, catalytic activity and defects, can be explained through the x values and the thermodynamic data calculated from the temperature and oxygen pressure dependences of the x' values.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.108-114
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• 1998

Salmonella Pathgenicity Island 2 plays an important role in Salmonella pathogenicity, especially invasion into host cell. We have investigated the effect of various environmental factors, such as oxygen level, osmolarity, pH, carbon starvation and glycerol addition on the expression of SPI2. For this research, we constructed the reporter plasmids, in which the promoter-less lac operons are fused with the regulatory regions (including promoter) of ssaJ and ssaK, major genes in SPI2. The study using the reporters showed that low oxygen, low osmolarity, or weak alkali conditions increased the expression levels of ssaJ and ssaK and when these three conditions exist simultaneously, the expression levels of ssaJ and ssaK are the highest. However carbon starvation and glycerol addition did not affect the expression of ssaJ and ssaK. These environmental effects on the expression levels of ssaJ and ssaK are the same in three Salmonella typhimurium wild types, LT2, UK1, and SL1344. In addition, we confirmed that the mutation in hilA, a regulatory gene encoding a transcriptional activator of SPI1, had no effect on the expression of ssaJ and ssaK. Thus, these results strongly suggest that the expressions of SPI2 and SPI1 are regulated by different control systems.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.632-639
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• 2021

In this research, fluorine doping was performed to enhance the photocatalytic activities of WO₃ which were measured using methylene blue dye. WO_3-xF_x photocatalyts were prepared by a vaper phase fluorination during a sintering for preparing WO₃ photocatalysts from a WCl₆ precursor. The bandgap energy of WO₃ photocatalysts decreased from 2.95 eV to 2.54 eV, and the oxygen vacancies site increased by about 55% after fluorine doping. In addition, the initial degradation efficiency of methylene blue showed that the fluorine doped sample showed a 6-fold increase in photocatalytic activities from 10% to 60% compared to that of the untreated sample. It is believed that fluorine is doped to reduce the band gap of photocatalysts, enabling the catalytic activity with low energy, and that oxygen vacancies-generated surface defects increase the visible light absorption region of WO₃ photocatalysts, thereby increasing photocatalytic activity. In this study, it was confirmed that fluorine-doped WO_3-xF_x photocatalysts with an excellent photocatalytic activity can be manufactured easily using a one-step vaper phase fluorination that does not require a post-treatment process.

• Ocean and Polar Research
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• v.28 no.4
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• pp.407-413
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• 2006

The effect of water temperature and photoperiod on the oxygen consumption of the fasted juvenile parrot fish, Oplegnathus fasciatus was investigated to provide empirical data for the early-stage culture management and bioenergetic growth model of the species. The mean body weight of the juvenile used for the experiment was $21.5{\pm}1.9g$, and the oxygen consumption rate was measured under four water temperatures (10, 15, 20 and $25^{\circ}C$) and three photoperiods (24L:0D, 12L:12D and OL:24D) with an interval of 5 minutes for 24 hours using a continuous flow-through respirometer. In each treatment three replicates were set up and 15 juveniles were totally involved. The oxygen consumption rates increased with increasing water temperature under all photoperiod treatments (P<0.001). Mean oxygen consumption rates at 10, 15, 20 and $25^{\circ}C$ ranged $202.1{\sim}403.4,\;306.7{\sim}502.2,\;536.7{\sim}791.0\;and\;879.9{\sim}1,077.4mg\;O_2\;kg^{-1}h^{-1}$, respectively. $Q_{10}$ values ranged $1.58{\sim}2.30$ between 10 and $15^{\circ}C,\;2.44{\sim}3.06$ between 15 and $20^{\circ}C\;and\;1.86{\sim}2.6y9$ between 20 and $25^{\circ}C$, respectively. Mean oxygen consumption rates of O. fasciatus were the highest in continuous light (24L:0D) followed by 12L:12D and 0L:24D (P<0.001). The oxygen consumption of fish exposed to the 12L:12D photoperiod was significantly higher during the light phase than during the dark phase under all temperature treatments (P<0.001). In summary, oxygen consumption rates of the juvenile parrot fish increase with increasing water temperature and lengthening daylight period; and, thereby, changes in water quality resulted from the depletion of oxygen under high temperature and long daylight photoperiod conditions should be monitored.

• Clinical and Experimental Pediatrics
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• v.46 no.2
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• pp.167-172
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• 2003

Purpose : Pulmonary vascular hypertension is a common problem in congenital heart disease, the most common cardiac condition in childhood. However, the mechanisms responsible for this pathologic change, treatment, and prevention are poorly understood. Therefore, we studied the gene expression of vascular endothelial growth factor(VEGF) by using a hypoxic model of the pulmonary artery smooth muscle cells. Methods : The main pulmonary artery and its proximal branches of a 6 wk old Fischer rat were excised. They were cut into multiple small pieces and suspended in DMEM medium supplemented with 20% fetal bovine serum and incubated in 5% $CO_2$-95% air atmosphere. The smooth muscle cells were confirmed by immunostaining with smooth muscle myosin and ${\alpha}$-smooth muscle actin antibodies. The VEGF gene expression in the hypoxic group was compared with the one in control the group as well as the one in the starved group by RT-PCR and Northern blot hybridization. Results : There was no statistically significant difference among the control, hypoxic and starved groups. Conclusion : There are few studies of pulmonary vascular hypertension at the molecular level in Korea. Therefore, we studied the expression of VEGF gene in hypoxic pulmonary vascular smooth muscle cells. Further studies will be needed to find the difference between newly born and adult rats, or human and rat pulmonary vascular smooth muscle cells in gene expression. We hope that the study will lead to a better understanding of pulmonary vascular hypertension.

• Clinical and Experimental Pediatrics
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• v.49 no.4
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• pp.455-459
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• 2006

The major pathogenesis of acute respiratory distress syndrome (ARDS) is an inflammatory process that results from a diversity of injuries to the body. Due to the various cytokines and vasoactive peptides released from the endothelium, the vascular permeability is increased; the migration of inflammatory cells and the leakage of plasma proteins then occur and edema develops in the alveolus. There is a hypothesis that the impairment of alveolar recruitment in ARDS is caused by a defect of the surfactant system and the resultant increase of alveolar surface tension. This has been studied in pediatric patients in ARDS; after the administration of surfactant, hypoxia, respiratory symptoms and survival chances were improved. To alleviate the major pathogenic mechanism in this disease, that is to say, inflammation of the lung, steroids have been used and studied as another treatment modality for ARDS, and it has been concluded that the administration of low dose methylprednisolone may improve patients' symptoms and survival rates. We report here on a case of a young infant admitted with ARDS, who, after the intratracheal administration of 120 mg/kg surfactant, on $PaO_2/FiO_2$ was elevated. Subsequent low doses of methylprednisolone were given, and the symptoms did not recur, and no fibrotic change was shown during the follow-up period of 2 months.