• 드라이브 ㆍ 컨트롤
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• 제10권2호
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• pp.1-6
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• 2013

This study describes a method which can attenuate reaction force effectively for an air spring system composed of an air spring and auxiliary chamber. For the analysis, the nonlinear governing equation of the air spring system is derived. For a performance improvement of the system, change of the heat transfer effect and the mass flow rates is included in the analysis of the air spring system. The simulation study is presented to show the reaction force is changed by variations in heat transfer characteristics and the air spring system of isothermal process has the best performance. As a result, to improve attenuation characteristics of reaction force, a process in the air spring system should be maintained near isothermal process.

• 대한화학회지
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• 제40권5호
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• pp.302-307
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• 1996

디에탄올아민 디티오카바메이트는 염화디스클로로비스에틸렌디아민)코발트(III)와 반응하여 [$Co(dtc)_3$](dtc=디에탄올아민 디티오카바메이트)를 생성한다. 이때 두 황원자는 코발트에 배위된다. 이 착물은 아세톤에 어느 정도 녹으나 이황산산소와 같은 비극성 용매에는 거의 녹지 않았다. 디에탄올아민 디티오카바메이트와 염화디스클로로비스에틸렌디아민)코발트(III)의 반응속도를 측정하고 이들 결과에서 얻어진 활성화 파라미터에서부터 가능한 메카니즘을 제시하고자 한다.

• Bulletin of the Korean Chemical Society
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• 제13권1호
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• pp.37-41
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• 1992

The reactions of nitrous acid with hydrogen peroxide in acidic aqueous solution in the presence of several added anions have been studied at $0^{\circ}C$ and pH 2-4 to investigate the nucleophilic catalysis of these anions. From the dependence of reaction rates on the anion concentrations, significant catalytic effects were found for $Cl^-,\;Br^-,\;SCN^-$, in order of effect $SCN^-\;{\approx}\;Br^->Cl^-$, while no observable effect was found for ${ClO_4}^-$ and ${NO_3}^-$. These results support O-nitrosation reaction is the rate-determining step and NOX formed in the presence of an anion ($X^-$) also acts as a nitrosating agent and accelerates the overall reaction rate. The order of reactivity was found to be NOCl>NOBr>NOSCN, which is consistent with the results of N-nitrosation and S-nitrosation reactions.

• Bulletin of the Korean Chemical Society
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• 제14권4호
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• pp.444-449
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• 1993

Anaerobic oxidation of D-penicillamine by Fe(III) in acidic solution has been studied kinetically by the use of stopped-flow system. The reaction is biphasic with a rapid complexation of 1: 1 complex, $Fepen^+$ (pen= D-penicillamine dianion) which is then internally reduced to Fe(II) and disulfide. Rates of both the complexation and the redox process are pH dependent and also are affected by the presence of chloride ion. Different from the reaction of Cu(II) with D-penicillamine, partially oxidized mixed-valence complex is not formed even transiently in this reaction.

• Journal of Electrochemical Science and Technology
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• 제14권3호
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• pp.243-251
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• 2023

Developing oxygen evolution reaction (OER) electrocatalysts is essential to accomplish viable CO₂ and water electrolysis. Herein, we report the fabrication and OER performance of Ni-foam (NF)-immobilized Ni₆ nanoclusters (NCs) (Ni₆/NF) prepared by a dip-coating process. The Ni₆/NF electrode exhibited a high current density of 500 mA/cm² for the OER at an overpotential as low as 0.39 V. Ni₆/NF exhibited high durability in an alkaline solution without corrosion. Electrokinetic studies revealed that OER can be easily initiated on Ni6 NC with fast electron-transfer rates. Finally, we demonstrated stable CO₂-to-CO electroreduction using an NC-based zero-gap CO₂ electrolyzer operated at a current density of 100 mA/cm² and a full-cell potential of 2.0 V for 12 h.

• 대한환경공학회지
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• 제33권6호
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• pp.420-425
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• 2011

순산소연소 조건하의 로내 탈황공정에서 황화반응 생성물인 $CaSO_4$의 재분해가 탈황반응에 미치는 영향이 크다. 본 연구에서는 DTF (Drop Tube Furnace)를 이용하여 반응온도, $CO_2$, $O_2$, $SO_2$, 농도 등을 포함한 다양한 실험 변수들이 $CaSO_4$ 탈황반응에 미치는 영향을 파악하기 위하여 분해반응의 전환율을 측정하고 반응속도를 계산하였다. 반응온도가 상승함에 따라 $CaSO_4$ 분해반응의 전환율과 반응속도가 증가하였고 $O_2$가 존재하는 조건에서 $CO_2$ 농도의 영향은 크지 않았다. 동일한 조건에서 $CaSO_4$ 분해속도는 $O_2$ 농도가 감소함에 따라 증가하였으나 $SO_2$ 농도가 증가함에 따라 감소되었다.

• Nuclear Engineering and Technology
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• 제28권4호
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• pp.349-358
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• 1996

The leaching behavior of uranium from unirradiated CANDU UO$_2$ fuel pellet in the spent fuel wet storage and disposal conditions has been investigated. A modified IAEA leach test method was used, and then the extent of leaching was monitored by analysis for uranium in the leachant. The leach test has been performed in various leachants(demineralized water and boric acid solution at pH=6, synthetic granite groundwater) for a long-term period of 5.4 years, and the effect of temperature on the leach rate of uranium has been analyzed. The leach rates of uranium at $25^{\circ}C$ were dependent on the leachants. Over initial 100 days of leach periods, the leach rate in groundwater was the highest in three leachants and no significant differences of leach rates ore observed in the demineralized oater and boric acid solution. But these leach rates in three leachants around 2,000 days at $25^{\circ}C$ appeared to be reached the steady rates in the range of 1~5$\times$10$^{-8}$ g/$\textrm{cm}^2$ day. The leach rate of uranium in groundwater shooed to be independent of the temperature, but those in both demineralized water and boric acid solution increased with temperature. These results show that the leaching behavior of uranium from UO$_2$ fuel in both the demineralized water ann boric acid may be controlled tv the surface oxidative.dissolution reaction of UO$_2$ and the leach rate of uranium in groundwater at room temperature could mainly be controlled by the complex reaction of dissolved uranyl ions with carbonate ions and no variation of leach rate of UO$_2$ in groundwater with temperature may be due to the local deposition of passivating uranyl phases on the surface.

• 한국산업융합학회 논문집
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• 제15권3호
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• pp.71-77
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• 2012

This study gives the optimal reaction conditions, reaction mechanisms, reaction rates leaded from the oxidation of phenol by electron beam accelerator and ozone used for recent water treatment. It gives the new possibility of water treatment process to effectively manage industrial sewage containing toxic organic compounds and biological refractory materials. The high decomposition of phenol was observed at the low dose rate, but at this low dose rate, the reaction time was lengthened. So we must find out the optimal dose rate to promote high oxidation of reactants. The reason why the TOC value of aqueous solution wasn't decreased at the low dose was that there were a lot of low molecular organic acids as an intermediates such as formic acid or glyoxalic acid. In order to use both electron beam accelerator and biological treatment for high concentration refractory organic compounds, biological treatment is needed when low molecular organic compounds exist abundantly in sewage. In this experiment, the condition of making a lot of organic acids is from 5 kGy into 20 kGy dose. Decomposition rate of phenol by electron beam accelerator was first order reaction up to 300ppm phenol solution on the basic of TOC value and also showed first order reaction by using both air and ozone as an oxidants.

• 한국염색가공학회지
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• 제19권4호
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• pp.18-25
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• 2007

Kinetics and mechanism for alkaline hydrolysis of C. I. Disperse Green 9(G-9) of dinitrothiophene disperse dye were investigated. As soon as G-9 contacted with alkali, instant and continuous decreases of color strength of G-9 followed with increasing time. The hydrolysis rate of G-9 increased with increasing alkali, and it was found that alkali appeared first order dependence. The observed rate constants obtained from hydrolysis of various amount of dye were similar values, and calculation of initial rates showed that G-9 hydrolyzed by first order reaction for dye. Therefore it was confirmed that the overall reaction was second order, $SN_2$ of nucleophilic substitution reaction. Increasing temperature enhanced the hydrolysis of G-9. From the results of hydrolysis performed at various temperatures, it was obtained that activation energy(Ea) was 12.6 kcal/mole, enthalpy of reaction(${\triangle}H$) was 12.0 kcal/mole, and entropy of reaction(${\triangle}S$) was $29.8J/mol{\cdot}K$.

• 한국표면공학회지
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• 제21권2호
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• pp.53-67
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• 1988

The high temperature corrosion of Fe-C alloys were studied at I atm SO gas in the temperature range 500~80$0^{\circ}C$ by means of a thermogravimetric analysis. The Na2SO4 induced high tempwrature corrosion rate was also measured at atm O2 gas under above the temperature renge. The reaction products were identified with the aid of X-ray diffraction technique, and micostruction of the alloy/scale interface was observed with a optical microscope and SEM. The experimental results were disussed by the themodeynamic calcutions. Under above the experimental condition. the reaction rates decrbon with increasing carbon content. The transfer of Fe ion was limited by a residue of carbon precipitated at alloy scale interface due to the oxidation of Fe-C alloys at alloy surface. The effect of cold working on reaction rate was different between the Fe containing low carbon and Fe-C Alloy containing carbon above 0,73 wt%. In a cold worked iron containing low carbon content, the crystallization of metal surface leads to the poor adherence between the alloy and the cavity formed between the alloy and scale. The outward diffusion of ion through the scale is estimated to be hindered by the cavity formed between the scale, consequently decreasing reaction rate. In the case Fe-C containing carbon above 0.73 Wt% alloy, the reaction rate was little affected by cold working, because the effect of content on reaction rats is greater than the effect of cold working.