• 한국세라믹학회지
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• 제40권11호
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• pp.1102-1105
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• 2003

광섬유 인선공정에 의해 생성된 실리카 유리내 점결함을 조사하였다. 본 연구에서는 특히 OH기가 적은 실리카 광섬유내 광섬유 인선 공정이 유발하는 oxygen deficient center와 E' center를 중점적으로 조사하였다. 광섬유 인선공정에 의해 oxygen deficient center 와 E’ center가 생성되었다는 것을 광학적 흡수대와 electron spin resonance를 이용하여 밝힐 수 있었다. 실리카 광섬유모재에서 가느다란 광섬유로 변환하는 neck-down 부분에서 점결함의 변화를 조사하였다. 점결함은 neck-down 부분에서 생성되며, 중심부분 보다 가장자리 부분에서 더 많은 점결함이 생성되었음을 알 수 있었다.

• 한국환경보건학회지
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• 제21권2호
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• pp.68-74
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• 1995

The optimum conditions was synthesized for the formation of Magnetite ($Fe_3O_4$) by air bubbling with the suspensions obtained by mixing Ferrous sulfate ($FeSO_4\cdot 7H_2O$) and Sodium Hydroxide (NaOH) solution in various values equivalent ratio($R=2NaOH/FeSO_4$) were studied. The changes of the structure were measured with XRD, $EM and BET. Equivalent ratio R: 0.65 was synthesized Goethite ($\alpha$-FeOOH), which becomes Maghemite ($\gamma=Fe_2O_3$) by dehydration, reduction and oxidation process. At the equivalent ratio over 1 (R>1), Magnetite ($Fe_3O_4$) was synthesized directly. The oxygen-deficient Magnetite ($Fe_3O_{4-\delta}$), which is obtained by flowing $H_2$ gas(100 ml/min) through the synthesis Magnetite at 350$\circ$C for 4 hr. By using it, was researched the decomposition reaction of $CO_2$. $CO_2$ was decomposed nearly 100% in 45 minutes by the oxygen-deficient Magnetite.

• Environmental Analysis Health and Toxicology
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• 제24권3호
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• pp.181-191
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• 2009

As an effort to prevent serious accidents involving oxygen deficiency and suffocation in confined spaces and to identify the causes of such accidents, the present study investigated relevant accidents and systems in Korea and other countries. This study also conducted a number of experiments at lethal concentration levels of oxygen deficiency using SD rats and observed the changes of experimental animals with humidity, organic gas (toluene), hydrogen sulfide, carbon monoxide and so on at the oxygen deficient environment. The results of the study are as follows. 1. The results from the experiment conducted using SD rats at lethal concentration levels of oxygen showed that there were no casualties at the 7% oxygen concentration level, but the mortality increase to 20% at 6% oxygen, it was jumped to 90% at 5% oxygen, and it was also dramatically reached 100% at 4% oxygen concentration. Therefore, 5.5% was calculated as the $LC_{50}$ (rat, 4hr) from these dose-response experiments with oxygen deficiency. 2. When we changed the level of toluene, $H_2S$, CO, humidity, and so on, in an oxygen deficient environment, it was observed that the small concentrations of $H_2S$ and CO make the highest effect on animals. In case of 350 ppm $H_2S$, it resulted in 30% mortality, and the 100% mortality was shown in 1,200 ppm CO concentration. The mortality increased as an oxygen deficient condition. However in the case of toluene up to 1,000 ppm, it were not affected with oxygen deficiency, and it did not indicate any significant differences in mortality as 20%, 90% humidities.

• 한국세라믹학회지
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• 제37권1호
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• pp.90-95
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• 2000

The ferrites, CuFe2O4 and SrFe12O129, were applied to decompose H2O for H2 generation. The ferrites prepared by the coprecipitation were reduced by CH4 gas to make the oxygen deficient ferrite. H2O was decomposed to form H2 by the oxygen deficient iron oxide, and the decomposition reactions were accelerated by the addition of divalent metals such as Cu and Sr in the ferrites. The spinel type CuFe2O4 containing a relatively large amount of divalent metals was more effective to H2 generation than magnetoplumbite type SrFe12O19 in H2O decomposition.

• 한국수산과학회지
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• 제41권2호
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• pp.134-139
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• 2008

To improve the oxygen-deficient water mass (ODW), the spatial and temporal variation in the water quality and characteristic of ODW occurrence were analyzed using yearly water quality data from 1989 to 2006 in Jinhae Bay, Korea. In addition, we estimated $ODW_{area},\;ODW_{vol.}$ and $ODW_R$ for Jinhae Bay. The overall water quality improved during the 2000s, based the annual variation in dissolved oxygen, chemical oxygen demand, etc. A cluster analysis classified Jinhae Bay into the southwestern, central, northern, and eastern regions. ODW occurred throughout the southwestern region in 1993 and 2002-2004, and the estimated $ODW_{vol.}$ was about $1.92km^3$. ODW did not occur in the eastern region because circulating seawater was exchanged in that part of Jinhae Bay. As ODW was generated every year in the southwestern region, this is the most polluted area in Jinhae Bay. The ODWR decreased in the northern region, showing that the water quality there has improved since a wastewater treatment plant began operating in 1994.

• 한국해양환경ㆍ에너지학회지
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• 제9권4호
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• pp.216-224
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• 2006

하계 가막만에서 발생하는 빈산소 수괴의 형성과정과 그 특성을 규명하기 위하여 2005년 6월 17일부터 2005년 9월 12일까지 주 간격으로 조사하였다. 표층 수온은 내만에서 만 입구로 갈수록 낮았으나, 저층 수온은 만 입구와 내만보다 만 중앙에서 높게 나타났다. 수괴의 수직적인 성층은 매우 발달하였으며, 수온약층은 수심 3-5m에서 관측되었다. 저층의 빈산소 수괴는 7월초에 내만 안쪽에서 나타났으며, 8월초에는 만 중앙부까지 확산되었다. 수괴의 평균투명도와 광소멸 계수($K_d$)는 각각 4.0m와 0.47로 나타났다. 저층의 영양염과 클로로필 ${\alpha}$ 농도는 표층보다 유의하게 높았으며, 만 입구보다 내만에서 높게 나타났다. 빈산소 수괴의 저층에서 퇴적물의 산소투과 깊이는 지극히 낮았으며, 산소소모율은 빈산소가 소멸된 수괴에서 보다 낮았다. 빈산소 수괴가 발생하는 기간동안 용존 산소 농도는 저층의 영양염 농도와 유의한 역 상관관계를 보였으나, 표층 영양염 농도와는 유의한 관계를 보이지 않았다. 저층에서 산소 감소의 촉진은 퇴적물에서 산소소모율 증가와 저층 부근에서 미생물에 의한 유기물 분해 때문인 것으로 판단되었다.

• 한국수산과학회지
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• 제27권4호
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• pp.413-433
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• 1994

진해만은 빈산소로 인한 수산생물의 생산성 저하가 현저하다. 본 연구에서는 진해만의 수질환경개선 및 회복을 위해서 빈산소 수괴의 형성방지가 무엇보다도 중요하다고 생각되어 해수유동 및 물질순환 모델을 이용하여 빈산소 수괴 형성상태를 재현하였고, 주요 오염부하가 용존산소에 미치는 영향의 정도를 예측하여 어장환경 관리방안을 도출한 결과는 다음과 같다. 저층의 용존산소 농도분포는 수온 및 밀도성층과 밀접한 관계를 가지고 변동하였고 수온성층이 가장 강했던 $6{\sim}7$월에 양식어장이 밀집된 진해만 서부해역과 마산만 해역에서 2.0mg/l이하의 빈산소 수괴가 형성되었다. 해수유동 모델에 의한 $M_2$분조 계산결과 창조시 유향의 주류는 가덕수로를 통하여 서쪽으로 이동하였고 일부는 마산만으로 유입되었으며, 낙조시는 반대방향이었다. 최강유속은 가덕수로 부근에서 발생하였고 진동만, 고현성만, 원문만등의 진해만 서부해역과 마산만에서는 5cm/sec이하로 미약하였다. 항유는 만 중앙부와 칠천도 사이에서 반시계방향의 환유가 형성되는 것이 특징적이었으며, 마산만이나 당황만 입구 부근에서는 표층의 경우 남향의 흐름이 나타났고, 저층에서는 북향의 흐름이 형성 되었다. 물질순환 모델의 보정결과 상관성은 0.85이상을 보였고 상대오차는 $28\%$이하의 범위내에서 여름철의 빈산소 수괴를 재현하였다. 각종 오염부하가 용존산소에 미치는 영향의 정도와 범위를 시뮬레이션을 통하여 예측한 결과 SOD가 전지역에 걸쳐 가장 큰 영향을 나타내었고 ,마산만의 유입부하도 용존산소 분포에 큰 영향을 미쳤으나 마산만내 국한되어 나타났으며, 양식생물에 의한 부하는 영향도 적었고 진해만 서부해역에 국한되었다. 빈산소 수괴가 강하게 형성되는 마산만과 진해만 서부해역의 빈산소 수괴 형성방지를 위해 효율적인 오염저감 대책으로서 마산만의 경우 유입 COD부하와 SOD를 저감해야하며, 진해만 서부해역의 경우 SOD가 주가 되어야 함을 알 수 있었다. 회복시켜야 할 용존산소 농도를 해역II등급인 5.0mg/l의 농도를 유지시키기 위해서는 마산만의 경우 유입되는 COD 부하를 $50\%$, SOD를 $70\%$로 저감해야 하며, 진해만 서부해역의 경우 SOD를 $95\%$, 양식생물 오염부하를 $90\%$까지 저감해야 되는 것으로 나타났다.

• Archives of Pharmacal Research
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• 제19권3호
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• pp.178-182
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• 1996

Using superoxide dismutase (SOD)-deficient mutants of Saccharomyces cerevisiae, the oxidative stresses induced by 0.1 mM of copper ion $(Cu^{++})$ was studied. In aerobic culture condition, yeasts lacking MnSOD (mitochondrial SOD) showed more significant growth retardation than CuZnSOD (cytoplasmic SOD)-deficient yeasts. However, not so big differences in growth pattern of those mutants compared withwild type were observed under anaerobic condition. It was found that, under aerobic condition, the supplementation of 0.1 mM copper ioh:(Cu") into culture medium caused the remarkable increase of CuZnSOD but not so significant change in MnSOD. It was also observed that catalase activities appeared to be relatively high in the presence of copper ion in spite of the remarkable reduction of glutathion peroxidase in CuZnSOD-deficient yeasts, but the slight increments of catalase and glutathion peroxidase were detected in MnSOD-deficient strains. It implies that the lack of cytoplasmic SOD could be compensated mainly by catalase. However, these phenomena resulted in the significantincrease of cellular lipid peroxides content in CuZnSOD-deficient yeasts and the slight increment of lipid peroxides in MNSOD-deficient cells. In anaerobic cultivation supplementing copper ion, the cellular enzyme activities of catalase and glutathion peroxidase in SOD-deficient yeasts were slightly increased without any significant changes of lipid peroxides in cell membrane. It suggests that a little amount of free radicals generated by copper ion under anaerobic condition could be sufficiently overcome by catalase as well as glutathion peroxidase.dase.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.155-155
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• 2010

Oxygen incorporated $Ge_2Sb_2Te_5$ (GST) films were prepared by an ion beam sputtering deposition (IBSD) method. From the I-V curves, the $V_{th}$ value varies with the oxygen content. Ge-deficient hexagonal phases are responsible for the observed unstability and decrease in $V_h$ values. In the case of a GST film with an elevated oxygen content of 30.8 %, the GST layer melted at 9.02 V due to the instability conferred by the high oxygen content. The formation of Ge-deficient hexagonal phases such as $GeSb_2Te_4$ and $Sb_2Te_3$ appear to be responsible for the $V_{th}$ variation. Impedance analyses indicated that the resistance in GST films with oxygen contentsof 16.7 % and 21.7 % had different origins. Thermal desorption spectroscopy (TDS)data indicate that moisture and hydrocarbons were more readily desorbed at higher oxygen content because the oxygen incorporated GST films are more hydrophilic than undoped GST films.

• Bulletin of the Korean Chemical Society
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• 제12권3호
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• pp.349-350
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• 1991