• 한국수소및신에너지학회논문집
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• 제34권1호
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• pp.38-46
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• 2023

Carbon neutrality policies have been strengthened to reduce emissions, and the importance of technology road maps has been emphasized. In the global industrial boiler market, carbon neutrality is implemented through fuel diversification of methane-hydrogen mixture gas. However, various problems such as flashback and flame unstability arise. There is a limit to implementing the actual system as it remains in the early stage. Therefore, it is necessary to secure the source technology of methane-hydrogen hybrid combustion system applicable to industrial fields. In this study, control program for methane-hydrogen fuel conversion was developed to expect various parameters. After determining the hydrogen mixing ratio and the input air flow, the fuel conversion control algorithm was constructed to get the parameters that achieve the target oxygen concentration in the exhaust gas. LabVIEW program was used to derive correlations among hydrogen mixing rate, oxygen concentration in exhaust gas, input amount of air and heating value.

• Corrosion Science and Technology
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• 제22권5호
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• pp.351-358
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• 2023

Although many thermal power plants use heat recovery systems, high exhaust gas temperatures are maintained due to corrosion at dew points and ash deposits caused by condensate formation. The dew point of exhaust gas is primarily determined by the concentration of SO₃ and steam, and various experiments and calculation equations have been employed to estimate it. However, these methods are known to be less suitable for exhaust gases with low SO₃ concentrations. Therefore, in this study, since the temperature of the exhaust gas is expected to decrease due to the low-load operation of the coal-fired power plant, sulfuric acid condensation and low-temperature corrosion are anticipated. We aimed to conduct a quantitative evaluation to propose ways to prevent damage by limiting operating conditions and improving facilities. The experimental results showed that the corrosion rate increased linearly with rising temperatures at a certain sulfuric acid concentration. Furthermore, variations in sulfuric acid concentrations generated during the current power plant operation process did not significantly affect the dew point, and the dew point of sulfuric acid under these conditions was observed to be between 120 - 130 ℃.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권2호
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• pp.36-44
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• 2013

The objectives of this study were to identify the characteristics of shallow groundwater from the oil-contaminated site for a long period and to evaluate the applicability of biopile technology to treat the soil excavated from it. The eight monitoring wells were installed in the contaminated site and pH, Electrical Conductivity (EC), Dissolved Oxygen (DO), Oxidation Reduction Potential (ORP), Temperature and the concentrations of major ions and pollutants were measured. The VOCs in soil gas were monitored during biopile operation and TPH concentration was analyzed at the termination of the experiment. The pH was 6.62 considered subacid and EC was 886.19 ${\mu}S/cm$. DO was measured to be 2.06 mg/L showing the similar characteristic of deep groundwater. ORP was 119.02 mV indicating oxidation state. The temperature of groundwater was measured to be $16.97^{\circ}C$. The piper diagram showed that groundwater was classified as Ca-$HCO_3$ type considered deep groundwater. The ground water concentration for TPH, Benzene, Toluene, Xylene of the first round was slightly higher than that of the second round. The concentration of carbon dioxide of soil gas was increased to 1.3% and the concentration of VOCs was completely eliminated after the 40 days. The TPH concentration showed 98% remediation efficiency after the 90 days biopile operation.

• 한국환경과학회지
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• 제20권10호
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• pp.1233-1241
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• 2011

The main objective of this experimental investigation was $CH_4$ recovery from biogas generated in municipal and wastewater treatment plant. The polysulfone hollow fiber membrane was prepared in order to investigate the permeation properties of $CH_4$ and $CO_2$. Permeability of $CO_2$ in Polysulfone membrane was 11-fold higher than of $CH_4$ gas. A membrane pilot plant for upgrading biogas was constructed and operated at a municipal wastewater treatment plant. The raw biogas contained 66 ~ 68 Vol % $CH_4$, the balance being mainly $CO_2$. The effect of the operating pressure of feed and permeate side and feed flowrate on $CH_4$ recovery concentration and efficiency were investigated with double stage membrane pilot plant. The $CH_4$ concentration in the retentate stream was raised in these tests to 93 Vol % $CH_4$.

• 생명과학회지
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• 제9권6호
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• pp.677-683
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• 1999

Gamdutang aqua-acupuncture solution (GAS), Gamdutang water-extracted solution (GWS) and Dae-Gamdutang aqua-acupuncture solution (DGAS) were prepared and tested for antitumor activities. It was shown to possess considerable toxicity toward various tumor cell lines. Concentration of 5 $\times$ and 10$\times$ of GAS resulted in more than 70% inhibition of growth in Ehrlich ascites tumor cells (EATC), Hepa1c1c7 and A549. GAS at concentrations of 5$\times$ and 10$\times$ revealed more than 60% inhibition in HeLa. GWS showed more than 50% inhibition of growth with EATC and HeLa at concentrations of 5$\times$ and 10$\times$, respectively. Toxicity assay with GWS in Hepa1c1c7 and A549 revealed that more than 80% inhibition of growth at the concentration of 5$\times$ and 10$\times$. In morphological study, the number of cells were decreased, and the shape of cells was round-form in EATC, Hepa1c1c7, A549, HeLa with GAS.

• 한국분무공학회지
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• 제11권1호
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• pp.30-38
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• 2006

High temperature furnaces such as power plant and incinerator contribute considerable part of NOx generation and face urgent demand of De-NOx system. Reducing agent is injected into the flue gas flow to activate do-NOx system. Almost SCR system adopt vaporized ammonia injection system. Vaporizer, dilution system and additional space are needed to gasify and inject ammonia. Liquid spray injection system can simplify and economize post-treatment system of flue gas. In this study, mixing caused by gas or liquid injection of reducing agent into flue gas duct was investigated experimentally. Carbonated water was used as tracer and simulated agent and mixing of liquid spray in a duct flow was studied. To achieve that, the angle of attack of static mixer is simulated and $CO_2$ concentration is measured.

• 한국산업융합학회 논문집
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• 제19권2호
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• pp.95-100
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• 2016

This study proposes the temperature compensation algorithm using thermopile detector for non-dispersive infrared Nitrogen gas sensor. From the output voltage of thermistor that is attached onto the infrared detector, the ambient temperature was extracted. The effects of temperatures on the properties of sensor module characteristics of narrow bandpass filter, optical cavity and infrared lamp, and air mixing gas have been introduced in order to implement the temperature compensation algorithm.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 춘계 학술대회논문집
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• pp.146-151
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• 2002

Characteristics of flow rate control has been studied for a cavitating venturi adopted in a liquid rocket propellant feed system. Numerical simulation has been peformed to give about $10\%$ discrepancy of mass flow rate to the experimental data for cavitating flow regime. Mass flow rate is confirmed to be saturated for pressure difference higher than $3\times10^5$pa when the upstream pressure is fixed to $22.8\times10^5$pa and the downstream pressure is varied. The evaporation amount depends substantially to non-condensable gas concentration. However the mass flow rate characteristic is relatively insensitive to the mass fraction of non-condensable gas. So it is reduced by only $2\%$ when the non- condensable gas concentration is increased from 1.5PPM to 150PPM. From the previous comparison the expansions of the non-condensable gas and the evaporation of liquid are verified to have same effect to pressure recovery.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.358-359
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• 2006

Ru-C nano-composite films were prepared by MOCVD, and their microstructures and their electrode properties for oxygen gas sensors were investigated. Deposited films contained Ru particles of 5-20 nm in diameter dispersed in amorphous C matrix. The AC conductivities associating to the interface charge transfer between Ru-C composite electrode and YSZ electrolyte were 100-1000 times higher than that of conventional paste-Pt electrodes. The emf values of the oxygen gas concentration cell constructed from the nano-composite electrodes and YSZ electrolyte showed the Nernstian theoretical values at low temperatures around 500 K. The response time of the concentration cell was 900 s at 500 K.

• 한국가스학회지
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• 제5권2호
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• pp.36-42
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• 2001

가정에서 일어나는 가장 일반적인 사고 중의 하나는 실내 가연성 가스누출에 의한 폭발 사고이다. 이러한 폭발 사고현장의 분석에 의하면 경우에 따라서 누출가스가 실내를 완전히 연소 하한계의 농도로 채올 수 있는 양보다 매우 작은 가연성 가스 양에 의하여 발생할 수 있다. 따라서 폭발이 일어날 수 있는 최소한의 가스 양은 실내 누출된 가스농도의 불균일한 정도에 의존하게 된다. 일반적으로 메탄과 같은 공기보다 가벼운 가스는 천장에서 축적되는 경향이 있고, 프로판의 경우에는 바닥에 축적되는 경향이 있다 본 논문에서는 매우 작은 양의 가스 누출에서 폭발 위험성 분석을 위한 가우스분포폭발 모델을 제시하였다. 이 모델은 연소한계농도에 기초를 두고, 특정 폭발 압력이 나타날 수 있는 최소한의 가스 누출량을 예측하는데 사용할 수 있다. 가우스모델을 이용하여 분석하면, 가정집에서 누출된 가스의 부피가 실내 부피에 비하여 $0.5\%$ 이하에서도 건물이 붕괴되는 폭발사고가 일어날 수 있다. 본 모델은 가스안전기기 개발을 위한 가스폭발 위험성 분석과 가정집에서 폭발사고 원인조사에 유용하게 활용될 수 있을 것으로 사료된다.