• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3607-3617
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• 2012

In this paper, the study of various ortho- and meta-substituted Magnolol derivatives is presented. The reaction enthalpies related to three antioxidant action mechanisms HAT, SET-PT and SPLET for substituted Magnolols have been calculated using DFT/B3LYP method in gas-phase and water. Calculated results show that electron-withdrawing substituents increase the bond dissociation enthalpy (BDE), ionization potential (IP) and oxidation/reduction enthalpy (O/RE), while electron-donating ones cause a rise in the proton dissociation enthalpy (PDE) and proton affinity (PA). In ortho- position, substituents show larger effect on reaction enthalpies than in meta-position. In comparison to gas-phase, water attenuates the substituent effect on all reaction enthalpies. In gas-phase, BDEs are lower than PAs and IPs, i.e. HAT represents the thermodynamically preferred pathway. On the other hand, SPLET mechanism represents the thermodynamically favored process in water. Results show that calculated enthalpies can be successfully correlated with Hammett constants (${\sigma}_m$) of the substituted Magnolols. Furthermore, calculated IP and PA values for substituted Magnolols show linear dependence on the energy of the highest occupied molecular orbital ($E_{HOMO}$).

• 한국안전학회지
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• 제1권1호
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• pp.27-32
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• 1986

To remove sulfur dioxide from flue gas by the method of metal oxide, copper powder of average diameter $2.4\mu\textrm{m}$and $51\mu\textrm{m}$ were used in a fixed bed reactor over a, temperature range of $300^{\circ}C-500^{\circ}C$. Copper oxide reacts with sulfur dioxide producing cupric sulfate and it can be regenerated from the latter by using hydrogen or methane. Experimental results showed that the reaction rate was increased by the increase of reaction temperature in the range of $300^{\circ}C-422^{\circ}C$ and the removal efficiency of sulfur dioxide was high in case of small size copper particle. However the removal efficiency was decreased at higher temperature due to decomposition of cupric sulfate. The rate controlling step of this reaction was chemical reaction and deactivating catalysts model can be applied to this reaction. The rate constants for this reaction and deactivation are as follows ： k＝8,367exp(-10,298/RT) Kd＝2.23exp(-8,485/RT)

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.198-201
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• 2001

The mixed gas of Hydrogen and Oxygen is gained from water electrolysis reaction. It has constant volume ratio 2 : 1 Hydrogen and Oxygen, and it is used as a source of thermal energy by combustion reaction. This gas has better characteristics in the field of economy, efficiency of energy, and environmental intimacy than acetylene gas and LPG used for gas welding machine. So several studies of this gas are actively in progress nowadays. The object of this study is the optimization of power condition in the side of electrical for the high efficiency of water electrolysis equipment. First, chemical analysis of electrolysis is conducted, and the relation of electrical energy and chemical energy is quantitatively investigated. For basic experiment, unit electrode of singular electrolysis electrode is manufactured and experimented, results are compared and analyzed with simulation, and the electrolysis is electrically equivalent.

• 한국대기환경학회지
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• 제12권4호
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• pp.479-485
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• 1996

Volatile organic compounds are air pollutants exhausting from industrial process, evaporation of solvent, and so on. Most of VOCs are the combustible gas of low calorific value as it is diluted by air. The systems burning such a hazardous gas need to increase enthalpy in order to increase flame stability. In this study an incinerator with reciprocating flow in the honeycomb ceramic has been used for the experiment of VOCs control. By the reciprocating flow system, the enthalpy of combustion gas is effectively regenerated into the enthalpy increases of the combustible gas through the honeycomb ceramic, which provides a heat storage. The position of the reaction zone is strongly dependent on the parameters of mixture velocity and time frequency. Flame front is changed to the point where burning velocity is coincided with burning velocity in the honeycomb ceramic. In this system it is important that flame front should be located symmetrically at the center of honeycomb ceramic for the purpose of increasing the reaction rate at one point. Peak temperature becomes higher with decreasing time frequency, at which the flow direction is regularly reversed.

• 한국수소및신에너지학회논문집
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• 제11권4호
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• pp.179-188
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• 2000

The anodic reaction of hydrogen/oxygen gas mixture at platinum or palladium electrode interfacing with a solid polymer electrolyte was investigated using AC impedance method. The impedance spectrum of the electrode reactions of the mixture depends on the gas composition, electrode roughness, the mode of electrochemical operation and the cell potential. For electrolysis mode of operation, the spectrum taken for the reaction on a rough platinum electrode for the gas mixture revealed clearly that the local anodic reduction of oxygen gas takes place concurrently with the anodic oxidation of hydrogen gas.

• 한국세라믹학회지
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• 제37권5호
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• pp.505-510
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• 2000

In this investigation, we fabricated RBSN (Reaction Bonded Silicon Nitride) using the static nitriding system which could be advantageous for commercialization. Firstly, Si compacts of different sizes were made, and then nitridation rates were investigated as a function of added static gas pressure. The reaction schedule was obtained by pre-experiments. In case of small samples, the variation of ${\alpha}$, ${\beta}$ phases between the inside and the outside region of the specimens was examined after the samples were nitrided under 1 bar and 1.5 bar reaction pressure. On the other hand, large samples of Si compact with the size of 36 mm for diameter and 23 mm for thickness were nitrided for 26 hours of the total nitridation time, which showed a complete and homogeneous nitriding reaction from the outside to the inside of the samples, although the time was considerably shorter than that needed for convertional nitridation. Nitridation rates obtained at the early stage of reaction were proportional to the reaction gas pressures. The sequences of the nitridation reaction with the thickness were as follows 1) the outside, 2) the inside and 3) the intermediate area of the specimen. These results wer eobtained from the coloration of cross sectioned specimens that had various nitridation rates. Total nitriding reaction kinetics was controlled by chemical reaction, not by diffusion of the nitrogen gas.

• 대한기계학회논문집B
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• 제32권8호
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• pp.597-603
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• 2008

The catalyzed diesel particulate filter (CDPF) is widely used for collecting soot from the exhaust gas of diesel engine. However, the CDPF need being regenerated after the soot accumulation. It is important to know characteristics of regeneration for CDPF with variation of exhaust gas temperature and composition. This study presents characteristics of regeneration according to variable exhaust gas composition. Furthermore, the experiment were performed variable gas temperature of CDPF inlet gas at each exhaust gas composition. Test-rig is used to control at each in let gas temperature and composition during regeneration of CDPF. Reaction intensity($I_c$) is used to compare with each result. Experimental results indicated that increased concentration of $NO_x$ and $O_2$ lead to regenerate more greatly. Also, higher temperature of exhaust gas leads to make CDPF cleaner.

• 공업화학
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• 제17권2호
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• pp.125-131
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• 2006

디메틸에테르(이하 DME)는 환경에 친화적인 새로운 청정에너지이다. 또한 DME는 다양한 에너지원으로부터 제조 되어지며, 그 에너지원으로는 천연가스, 석탄, 바이오매스, 폐플라스틱 등이 있다. 이런 DME는 LPG와 매우 유사한 성질을 특징으로 가지고 있다. 이러한 결과로 DME는 LPG, 연료전지, 발전연료, 특히 디젤의 대체 연료로 고려되고 있으며, 2010년 대체 에너지로 기대되고 있다. DME 직접합성반응의 반응속도를 측정하기 위하여 서로 다른 조건인 온도 $220{\sim}280^{\circ}C$, 합성가스 비율 1.2~3.0에서 실험을 수행하였다. 모든 실험은 혼성촉매를 사용하여 수행하였으며, 혼성촉매는 메탄올 합성 촉매와 메탄올 탈수촉매가 포함되어 있다. 반응속도는 랭미어-힌쉘우드 타입의 반응 메커니즘을 따르며, 메탄올 합성반응, 메탄올 탈수반응, 수성가스 전환반응, 이 세 가지 반응의 메커니즘을 고려하였다. 각 반응의 반응속도는 촉매상의 표면반응과 수소와 메탄올, 그리고 물의 해리흡작으로 결정하였다.

• 한국수소및신에너지학회논문집
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• 제28권5호
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• pp.561-569
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• 2017

In this study, a synthetic amine made using the ethylene oxide-ammonia reaction was used as an absorbent to remove carbon dioxide. Existing absorbents were used in a mix in order to improve performance; however, because the ethylene oxide-ammonia reaction generates primary, secondary, and tertiary amines simultaneously, it has the merit that separate mixing of the absorbents was not needed. The performance of carbon dioxide absorption with the synthetic amine was compared to that of MEA. As a result of an experiment, it was determined that the $CO_2$ loading was 1.15 times better than that of MEA (a commonly used amine), while the cyclic capacity was 2.28 times higher. Because the heat of reaction was 1.10 times lower than for MEA, the synthetic amine showed superior performance in terms of absorption and regeneration.

• 자원리싸이클링
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• 제30권6호
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• pp.12-18
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• 2021

수성가스 전환 반응은 가스화로 생성된 합성 가스에 수소 생산 증가와 H₂/CO 비율 제어를 위해 수증기를 첨가하는 가스화 후속 공정이다. 본 연구에서는 RPF(Refuse plastic fuel) 가스화 시스템의 합성가스를 대상으로 수성가스 전환 반응을 연구하였다. 수성가스 전환 반응은 촉매를 이용하여 high temperature shift(HTS) 와 low temperature shift(LTS) 반응에 대하여 lab scale 관형 반응기를 이용하여 반응 온도, steam/carbon ratio, 유량의 변화가 H₂ 생성과 CO 전환율에 미치는 영향을 조사하였다. 운전 온도는 HTS 시스템이 250-400℃, LTS 시스템이 190-220℃이며 steam/carbon ratio는 1.5-3.5로 변화시켰다. 반응 모의 가스의 농도는 RPF 합성가스의 농도를 기준으로 CO, 40vol%, H₂, 25vol%, CO₂, 25vol%이다. 반응 온도와 steam/carbon ratio가 증가함에 따라 CO 전환율 및 H₂ 생성량이 증가하고, 유량이 증가하면 촉매층의 체류시간 단축으로 CO 전환율과 H₂ 생성량이 감소하였다.