• 한국안전학회지
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• 제11권2호
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• pp.67-78
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• 1996

Gas sensing element, $\gamma-Fe_2O_3$was synthesized by dehydration, reduction, and oxidation of $$${\gamma}$-FeOOH, which was synthesized with $FeSO_4\;{\cdot}\;7H_2O$ and NaOH. They were produced as a bulk-type, a thick film-type. Then, their responses and mechanisms of response to the gas of liquefied-petroleum were studied. The qualities of gas sensing elements are decided by the structure and the relative surface area. In the process of $\alpha-FeOOH $synthesis, the effects of reaction conditions as the equivalent ratio, on the structure and the relative surface area of gas sensing element were observed. The changes of the structure were measured with XRD, SEM, TG-DTA and BET. The resistance changes of the synthesized gas sensor in the air were measured. The response ratio were also measured for the changes of working temperature and gas concentration. As a result of analysis with XRD, it was confirmed that the the best conditions for the synthesis of $\alpha -FeOOH$ were equivalent ratio 0.65. The thick film-type element of $\gamma-Fe_2O_3$responded more quickly than the bulk-type did. The structure and the relative surface area of the $\alpha-FeOOH $were confirmed as the important factors deciding gas response charcteristics.

• 대한기계학회논문집B
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• 제34권8호
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• pp.761-766
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• 2010

본 연구는 등가가스를 이용하여 다양한 조성의 천연가스에 대한 부분예혼합 가스기기의 호환성 판정법을 실험을 통하여 검토 제시하였다. 본 판정법을 위해, 가정용 가스레인지를 이용 등가가스와 천연가스의 화염을 비교 하였으며, 화염의 부상 및 불완전연소에 대해 측정을 하여 KS 규격과 비교하였다. 그 결과, 등가가스와 천연가스의 화염은 화염길이, 화염색, 화염모양 등의 차이가 거의 없었다. 또한 화염의 부상 발생은 웨버지수 51 MJ/$m^3$ 이상에서 안정함을 보였으며, 불완전 연소지수의 경우, 웨버지수 56.3 MJ/$m^3$에서 CO 농도가 95~100 ppm 정도를 보여주었다. 결과적으로 천연가스에 대한 화염의 부상과 불완전연소에 대해 호환 범위를 웨버지수 51~56.3 MJ/$m^3$로 제안하였으며, 이 범위 내의 천연가스는 국내 가정용 부분예혼합 가스기기에 대해 호환 가능하다는 의미이다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.196-197
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• 2010

This paper investigates a high performance converter topology for hydrogen gas generation electrolysis system. The proposed converter topology consists of full-bridge inverter, medium frequency transformer, and diode rectifier. Hydrogen gas generation electrolysis process considered in the paper is analyzed and characterized by its equivalent circuit. The electrolysis cell is modeled as effective resistance, capacitance, inductance, and internal emf voltage source. The proposed converter topology provides enhanced efficiency of hydrogen gas generation process under the operating condition of dc output voltage with high frequency ripple on it. The high performance operation of proposed converter is confirmed through the simulation with the electrolysis cell considered in the equivalent circuit model.

• 에너지공학
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• 제24권4호
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• pp.117-123
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• 2015

최근 산업체에서는 성분을 알 수 없거나, 데이터베이스를 보유하지 않는 가스들의 사용이 증가하고 있는 추세이다. 가스들의 사용양이 증가함에 따라 확산범위와 속도를 예측 할 수 있는 소프트웨어들이 사용의 중요성이 증가하고 있는데, 이들 소프트웨어들은 기존에 보유하고 있는 가스들의 자료에 의존하여 확산거리 및 속도를 예측하기 때문에 새로운 가스들이 확산거리(속도)를 예측하기는 매우 어려운 실정이다. 따라서 본 연구에서는 가스의 확산 및 폭발을 예측할 수 있는 FLACS S/W 및 등가가스를 이용하여 불특정한 가스들의 확산을 예측할 수 있는 방법을 제시하고자 한다.

• 센서학회지
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• 제15권1호
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• pp.34-39
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• 2006

This study provides the electrical model of combustible catalytic gas sensor. Physical characteristics such as thermal behavior, resistance change were included in this model. The finite element method analysis for sensor device structure showed that the thermal behavior of sensor is expressed in a simple electrical equivalent circuit that consists of a resistor, a capacitor and a current source. This thermal equivalent circuit interfaces with real electrical circuit using two parts. One is 'power to heat' converter. The other is temperature dependent variable resistor. These parts realized with the analog behavior devices of the SPICE library. The gas response tendency was represented from the mass transferring limitation theory and the combustion theory. In this model, Gas concentration that is expressed in voltage at the model, is converted to heat and is flowed to the thermal equivalent circuit. This model is tested in several circuit simulations. The resistance change of device, the delay time due to thermal capacity, the gas responses output voltage that are calculated from SPICE simulations correspond well to real results from measuring in electrical circuits. Also good simulation result can be produced in the more complicated circuit that includes amplifier, bios circiut, buffer part.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2001년도 추계학술발표회 논문집
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• pp.3-15
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• 2001

• 한국대기환경학회지
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• 제15권2호
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• pp.183-190
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• 1999

Magnetite was synthesized with $FeSO_4$, and NaOH for the decomposition of carbon dioxide and for the study of the methane formation. The chemical equivalent ratio was changed from 0.5 to 1.50 for the magnetite synthesis. The chemical equivalent ratio was fixed in 1.00, and Nickel chloride and Rhodium chloride equally added and synthesized with the ratio was of 0.10~10.00 mole%. The crystal strucure of the synthesized magnetite was measured XRD. Putting synthesized magnetite in the reactor and using hydrogen gas oxygen-deficient magnetite was made. Injecting carbon dioxide in the reactor, the decomposition reaction was experimented. The formation of methane was confirmed injecting hydrogen gas in the reactor after carbon dioxide was decomposed.

• 에너지공학
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• 제9권2호
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• pp.83-88
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• 2000

In this study, the performance and pollutant emission of CNG engine using diesel oil as a source of ignition, so called CNG dual fuel diesel engine is considered by experiment. One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of total hydrocarbon (THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrogen was applied to engine test. The results showed that the higher the mixture ratio of hydrogen to natural gas, the higher the combustion efficiency. and when the amount of the intake air is reached to 90% of WOT, the combustion efficiency was promoted. But, like a case making the injection timing earlier, the equivalent mixture ratio for the knocking limit decrease and the produce of NOx increases.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 춘계 학술발표회 논문집
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• pp.95-100
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• 1999

One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of Total Hydrogen Carbon(THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrohen was applied to engine test. The results showed that the higher the mixture ratio of hydrogen to natural gas, the higher the combustion efficiency. And when the amount of the intake air is reached to 90% of WOT, the combustion efficiency was promoted. But, like a case making the injection timing earlier, the equivalent mixture ratio for the nocking limit decreases and the produce of NOx increases.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.121-122
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• 2002

This paper presents contact behavior of an Polyperfluoroalkoxyethylene(PTFE) ring seals by a non-linear finite element method using the thermomechanical analysis. PTFE elastomer was assumed as odgen model for numerical analysis in FEM commercial code because elastomer has nonlinear behaviour character. The shape effects are investigated for sealing performance of ring seal in boundary conditions which as gas pressure, groove temperature and various O-ring seal models. Also contact stress and equivalent total strain are investicated. An O-ring seals was modeled four shape which are circle, two sunflower and X. The highest contact stress occurs at sunflower-ring seal with groove deapth of 0.35mm. the equivalent total strain of sunflower-ring seal is lower than that of the others under low gas pressure condition but under gas pressure condition over 4Mpa, that of sunflower-ring seal is higher. The calculated FEM results shows that the Sunflower-ring seal with groove depth of 0.35mm has excellent performance compared with other seal models.