• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.417-423
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• 2007

Oxy-gasification or oxygen-blown gasification, enables a clean and efficient use of coal and opens a promising way to CO2 capture. The coal gasification process of a slurry feed type, entrained-flow coal gasifier was numerically predicted in this paper. The purposes of this study are to develop an evaluation technique for design and performance optimization of coal gasifiers using a numerical simulation technique, and to confirm the validity of the model. By dividing the complicated coal gasification process into several simplified stages such as slurry evaporation, coal devolatilization, mixture fraction model and two-phase reactions coupled with turbulent flow and two-phase heat transfer, a comprehensive numerical model was constructed to simulate the coal gasification process. The influence of turbulence on the gas properties was taken into account by the PDF (Probability Density Function) model. A numerical simulation with the coal gasification model is performed on the Conoco-Philips type gasifier for IGCC plant. Gas temperature distribution and product gas composition are also presented. Numerical computations were performed to assess the effect of variation in oxygen to coal ratio and steam to coal ratio on reactive flow field. The concentration of major products, CO and H2 were calculated with varying oxygen to coal ratio (0.2-1.5) and steam to coal ratio(0.3-0.7). To verify the validity of predictions, predicted values of CO and H2 concentrations at the exit of the gasifier were compared with previous work of the same geometry and operating points. Predictions showed that the CO and H2 concentration increased gradually to its maximum value with increasing oxygen-coal and hydrogen-coal ratio and decreased. When the oxygen-coal ratio was between 0.8 and 1.2, and the steam-coal ratio was between 0.4 and 0.5, high values of CO and H2 were obtained. This study also deals with the comparison of CFD (Computational Flow Dynamics) and STATNJAN results which consider the objective gasifier as chemical equilibrium to know the effect of flow on objective gasifier compared to equilibrium. This study makes objective gasifier divided into a few ranges to study the evolution of the gasification locally. By this method, we can find that there are characteristics in the each scope divided.

• 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.

• 한국자기학회지
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• 제3권3호
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• pp.229-233
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• 1993

광자기 디스크의 제조시 기록막내부의 산소함량에 따른 기록 및 자기적 특성의 변화를 연구하였다. 기록막내의 산소함량 변화는 반응성 스퍼터링에 의해 조절하였으며 스퍼터링 전과정 동안 산소의 거동을 in-situ 잔류가스분석기로 조사하였다. 산소함량의 증가에 따라 보자력은 감 소하였으나 수직이방성 및 수직 각형비등은 변화하지 않았다. 대부분의 첨가된 산소는 스퍼터링 과정중 소모되어 Tb원자와 안정한 산화물을 형성하여 자기적 조성의 변화를 초래하였지만 임계기 록크기와 임계외부자계크기에만 약간의 변화를 가져왔을 뿐 디스크의 기록신호잡음비에는 별로 영향을 미치지 않았다. 또한 디스크의 신뢰도면에서도 크게 감소하지 않았다.

• 한국분말재료학회지
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• 제9권1호
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• pp.32-37
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• 2002

In the present study of IGC (Inert Gas Condensation) evaporation-condensation processing study, the effects of IGC convection gas on the crystallographic structure, size and shape of tin oxide nanoparticles were investigated. In addition, the phase transformation of tin oxide nanoparticles was studied after heat treatment. IGC processing was conducted at 1000℃ for 1 hr. The mixture gas of oxygen and helium was used as a convection gas. Metastable tetragonal SnO nanoparticles were obtained at a lower convection gas pressure, whereas amorphous tin oxide nanoparticles were obtained at a higher one. The formation of amorphous phase could be explained by the rapid quenching of the vaporized atoms. The resultant nanoparticles size was about 10 nm with a rounded shape. The tin oxide nanoparticles prepared by IGC were almost transformed to the stable tetragonal SnO₂ after heat treatment.

• 한국연소학회지
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• 제10권2호
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• pp.26-34
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• 2005

The performance of oxygen combustion with $CO_2$ feeding was investigated in a pyrex tube furnace. The inverse type multi-hole burner was used for improving mixing and wide operating range. It introduced oxygen, fuel, and oxygen, respectively, from center tube to outer tubes. Oxygen combustion characteristics with excess oxygen ratio, oxygen feeding ratio, and $CO_2$ feeding flow rate were studied to optimize the operating condition and to apply the oxygen combustion with recirculation of flue gas to a real furnace. This paper presents results on the effect of $CO_2$ feeding flow rate on the structure of the flames and concentrations of NO and CO emissions. The visible flame length was shortest due to well mixing between fuel and oxygen when the oxygen feeding ratio was 0.25. The NO emission was reduced drastically regardless of excess oxygen ratio when the $CO_2$ feeding flow rate was larger than 15 lpm. The CO emission is varied by changing the $CO_2$ feeding flow rate but the CO emission characteristics is highly affected by excess oxygen ratio. When the excess oxygen ratio is below $\lambda=1.1$, the CO emission increased as the $CO_2$ feeding flow rate increased.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.162-169
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• 2005

The performance of oxygen combustion with $CO_2$ feeding was investigated in a pyrex tube furnace. The inverse type multi-hole burner was used for improving mixing and wide operating range. It introduced oxygen, fuel, and oxygen, respectively, from center tube to outer tubes. Oxygen combustion characteristics with excess oxygen ratio, oxygen feeding ratio, and $CO_2$ feeding flow rate were studied to optimize the operating condition and to apply the oxygen combustion with recirculation of flue gas to a real furnace. This paper presents results on the effect of $CO_2$ feeding flow rate on the structure of the flames and concentrations of NO and CO emissions. The visible flame length was shortest due to well mixing between fuel and oxygen when the oxygen feeding ratio was 0.25. The NO emission was reduced drastically regardless of excess oxygen ratio when the $CO_2$ feeding flow rate was larger than 15 lpm. The CO emission is varied by changing the $CO_2$ feeding flow rate but the CO emission characteristics is highly affected by excess oxygen ratio. When the excess oxygen ratio is below ${\lamda}=1.1$, the CO emission increased as the $CO_2$ feeding flow rate increased.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.238-244
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• 2005

This study performs the pilot-plant experiments to evaluate the effect of the oxygen enrichment on the co-incineration of municipal solid waste and organic sludge from a wastewater treatment facility. The design capacity of the stoker-type incinerator pilot-plant is 150 kg/h. Combustion chamber temperatures were measured as well as the stack gas concentrations, i.e., NOx, CO, and the residual oxygen. The maximum ratio of organic sludge waste to the total waste input is 30%. Also the oxygen-enriched air with 23% of oxygen in supplied air is used for stable combustion. As the co-incineration ratio of the sludge increased up to 30% of the total waste input, the primary and the secondary combustion chamber temperature was decreased $to900^{\circ}C$ (primary combustion chamber), $750^{\circ}C$(secondary combustion chamber), respectively, approximately $200^{\circ}C$ below the incineration temperature of the domestic waste only (primary: $1,100^{\circ}C$, secondary: $950^{\circ}C$). However, if the supplied air was enriched to 22% oxygen content in air, the incinerator temperature was high enough to burn the waste mixture with 30% sludge, which has the heating value of 1,600 kcal/kg.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.246-249
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• 2009

산소를 추진제로 사용하는 발사체를 발사하기 위한 발사대 및 그것을 시험하기 위한 설비를 보유하고 있는 건물은 언제나 누출된 산소로 인한 화재 및 폭발의 위험성을 지니고 있다. 또한 질소, 헬륨 등과 같은 각종 고압가스류를 사용하고 있기 때문에 밀폐된 공간에서의 가스 누출로 인한 질식사의 위험에도 노출되어 있다. 따라서 이러한 공간 내의 공기 중 산소 농도를 관리하여 발생할 수 있는 사고를 미연에 예방할 수 있어야 한다. 본 논문에서는 산소 농도 관리의 방법과 시스템 구성 및 적용 결과를 정리하였다.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3395-3399
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• 2011

Copper oxide thin films were synthesized by reactive radio frequency magnetron sputtering at different oxygen gas ratios. The chemical and physical properties of the thin films were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). XPS results revealed that the dominant oxidation states of Cu were $Cu^0$ and $Cu^+$ at 0% oxygen ratio. When the oxygen ratios increased above 5%, Cu was oxidized as CuO as detected by X-ray induced Auger electron spectroscopy and the $Cu(OH)_2$ phase was confirmed independent of the oxygen ratio. The valence band maxima were $1.19{\pm}0.09$ eV and an increase in the density of states was confirmed after formation of CuO. The thickness and roughness of copper oxide thin films decreased with increasing oxygen ratio. The crystallinity of the copper oxide films changed from cubic Cu through cubic $Cu_2O$ to monoclinic CuO with mean crystallite sizes of 8.8 nm (Cu) and 16.9 nm (CuO) at the 10% oxygen ratio level.

• Tuberculosis and Respiratory Diseases
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• 제63권3호
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• pp.242-250
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• 2007

배경 및 목적: 암세포는 빠른 증식 속도로 인하여 상대적인 저산소증에 노출되면서 비정상적인 종양 혈관을 형성하여 치명적인 병인을 형성한다. 저산소증에서의 암세포 내의 유전자 표현을 연구하는 것은 병인의 규명과 나아가 치료에 결정적인 단초를 제공할 수 있다. 이에 본 연구에서는 체외 배양한 비소세포폐암의 증식과 저산소증 상태에 대한 연구를 시행하였다. 재료 및 방법: 비소세포폐암주인 A549를 RPMI 배지에서 계대 배양하였다. 저산소 유사 상태는 Modular Incubator Chamber(MIC-101)을 이용하였고 5% 이산화탄소와 95% 질소 혼합 가스를 5분간 공급하여 저산소 상태를 만들었으며 세포 배양액을 채취하여 혈액가스분석기(Blood Gas Analyzer ABL 725)로 세포 배양 상태를 측정하였다. 대조군으로 5% $CO_2$와 멸균한 대기 공기 95%가 혼합된 가스를 사용하였다. 세포의 증식 상태는 MTT 방법을 실시하였다. 결과: 1. MIC-101을 이용하였을 때, 무산소혼합가스를 투여 후 30분에 50%의 산소 분압저하를 확인하였으며, 대기 가스에 의해 산소농도를 회복하는 것을 볼 수 있었다. 2. 무산소 혼합가스로 정화(purging)를 하면 산소의 분압을 더 낮출 수 있었다. 3. 저산소 상태에서 세포 배양액 내에는 pH 감소, 젖산 증가, 포도당의 감소와 같은 미세환경이 변하였다. 4. 세포배양액에 따라 저산소에 의해 유도되는 포도당 저하에 차이가 있었다. 5. 비소세포폐암주는 저산소에 의해 증식능이 억제되었다. 결론: 저산소 상태는 세포 배양액 내 포도당 농도의 감소, 젖산의 증가, pH의 감소 등 세포 배양 미세 환경을 변화시키며, 비소세포폐암세포는 증식이 억제된다. 저산소는 미세 환경 변화와 함께 직접적으로 그리고 간접적으로 비소세포의 증식능에 영향을 미친다.