Chemical Reaction Engineering in the Chemical Processing of Metals and Inorganic Materials Part l. Advances in Fluid-Solid Reaction Analysis

Sohn, Hong Yong 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.2

The advances made in the field of chemical engineering as applied to the processing of metals and other inorganic materials are reviewed. The reactions involved in this field are heterogeneous in nature, the fluid-solid noncatalytic reactions being the most important group of examples. In these heterogeneous reactions, interfacial chemical reactions are always accompanied by the transfer of mass and heat between the reaction interface and the bulk fluid. The interplay of these steps determines the overall characteristics and analysis of the reaction rate. The review examines the developments in the quantitative rate analysis of various fluid-solid reaction systems. Examples are largely drawn from the work of the author and coworkers, which has led to the formulation of the Law of Additive Reaction Times and its application to a wide range of fluid-solid reactions. The serious effects of the thermodynamics on fluid-solid reaction with small equilibrium constants, in terms of the overall rate and the falsification of activation energy, have been examined based on a careful quantitative analysis.

환자 이동 작업 시 보조도구를 사용하여 옮기는 동작과들어서 옮기는 동작의 역학적 분석

이희성,우지혜,김희수 대한치료과학회 2018 대한치료과학회지 Vol.10 No.1

Objective: The purpose of this study is to analyze the kinetics and kinematics difference between transferring motion using assistance tools and lift transferring motion during transferring a patient to a wheelchair. Method: From September to October 2012, 27 healthy normal adults in their 20s were randomly selected and divided into two groups: 14 using a board group and 13 using no board. An independent t-test was used to compare the differences among each of the independent variables, such as the change of range of motion(ROM), maximum vertical ground reaction force(VGRF) and vertical joint reaction force(VJRF) during patient transfer. Results: Transferring motion using assistance tools showed significantly less change of trunk anterior flexion-extension, maximum vertical ground reaction force and vertical joint reaction force respectively than lift transferring motion.

Fragmentations and Proton Transfer Reactions of Product Ions Formed from Mono-, Di-, and Triethanolamines

Sung-Seen Choi*,소헌영 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.10

Fragmentations and proton transfer reactions of mono-, di-, and triethanolamines were studied using FTMS. It was found that the most abundant fragment ion was [M−CH2OH]+. The [M−CH2OH−H2O]+ was observed in the mass spectra of diethanolamine and triethanolamine. By increasing the ion trapping time in the ICR cell, the [M+H]+ and [M+H−H2O]+ ions were notably increased for all the samples while the [M+H−2H2O]+ was observed in the mass spectra of diethanolamine and triethanolamine. The proton transfer reactions between the fragment ions and neutral molecules occurred predominantly by increasing the ion trapping time. The rate constants for the proton transfer reactions were calculated from experimental results. The proton transfer reaction of CHO+ was the fastest one, which is consistent with the heats of reaction. The rate constants for proton transfer reactions of triethanolamine were much slower than those of ethanolamine and diethanolamine because of the steric hindered structure of triethanolamine. The plausible structures of observed ions and heats of reaction for proton transfer were calculated with AM1 semiempirical method.

Proton Transfer Reactions and Ion-Molecule Reactions of Ionized XCH₂CH₂Y (X and Y = OH or NH₂)

Choi, Sung-Seen,So, Hun-Young Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.4

Proton transfer reactions and ion-molecule reactions of bifunctional ethanes of $H_2NCH_2CH_2NH_2$, $H_2NCH_2CH_2OH$, and $HOCH_2CH_2OH$ were studied using Fourier transform mass spectrometry (FTMS). The rate constants for proton transfer reactions between the fragment ions and neutral molecules were obtained from the temporal variation of the ion abundances. The rate constants were consistent with the heats of reaction. The fastest proton transfer reactions were the reactions of $CH_2N^+$, $CHO^+$, and $CH_3O^+$ for $H_2NCH_2CH_2NH_2$, $H_2NCH_2CH_2OH$, and $HOCH_2CH_2OH$, respectively. The $[M+13]^+$ ion was formed by the ion-molecule reaction between $H_2C=NH_2 ^+$ or $H_2C=OH^+$ and the neutral molecule. The major product ions generated from the ion-molecule reactions between the protonated molecule and neutral molecule were $[2M+H]^+$, $[M+27]^+$, and $[M+15]^+$.

Fragmentations and Proton Transfer Reactions of Product Ions Formed from Mono-, Di-, and Triethanolamines

Choi, Sung-Seen,So, Hun-Young Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.10

Fragmentations and proton transfer reactions of mono-, di-, and triethanolamines were studied using FTMS. It was found that the most abundant fragment ion was $[M-CH_2OH]^+$. The $[M-CH_2OH-H_2O]^+$ was observed in the mass spectra of diethanolamine and triethanolamine. By increasing the ion trapping time in the ICR cell, the $[M+H]^+$ and $[M+H-H_2O]^+$ ions were notably increased for all the samples while the $[M+H-2H_2O]^+$ was observed in the mass spectra of diethanolamine and triethanolamine. The proton transfer reactions between the fragment ions and neutral molecules occurred predominantly by increasing the ion trapping time. The rate constants for the proton transfer reactions were calculated from experimental results. The proton transfer reaction of $CHO^+$ was the fastest one, which is consistent with the heats of reaction. The rate constants for proton transfer reactions of triethanolamine were much slower than those of ethanolamine and diethanolamine because of the steric hindered structure of triethanolamine. The plausible structures of observed ions and heats of reaction for proton transfer were calculated with AM1 semiempirical method.

Mechanism in pH effects of electrochemical reactions: a mini-review

Liu Sibei,Wang Zhuowen,Qiu Shan,Deng Fengxia 한국탄소학회 2024 Carbon Letters Vol.34 No.5

pH plays a pivotal role in influencing various aspects of proton-coupled electron transfer (PCET) reactions in electrochemical systems. These reactions are affected by pH in terms of mass transport, electrochemical double layer (EDL) structure, and surface adsorption energy, all of which impact the overall electrochemical processes. This review article aims to provide a comprehensive understanding of the research progress made in elucidating the effects of pH on different electrochemical reactions, the hydrogen evolution reaction/hydrogen oxidation reaction (HER/HOR), oxygen reduction reaction/oxygen evolution reaction (ORR/OER), and carbon dioxide reduction reaction (CO2RR). To embark on this endeavor, we have conducted a bibliometric analysis to clearly outline of the research trends and advancements in the field concerning the pH effects. Subsequently, we present a systematic overview of the mechanisms governing these reactions, with a special focus on pH’s influence on both the proton and electron aspects. We conclude by discussing the current challenges in this area and suggesting future research avenues that could further our understanding of pH's role in electrochemical reactions.

촉매 연소를 열원으로 한 수증기-메탄개질반응 전산유체해석

이정섭,이강훈,유상석,안국영,강상규 한국수소및신에너지학회 2013 한국수소 및 신에너지학회논문집 Vol.24 No.2

A steam reformer is a chemical reactor to produce high purity hydrogen from fossil fuel. In the steam reformer, since endothermic steam reforming is heated by exothermic combustion of fossil fuel, the heat transfer between two reaction zones dominates conversion of fossil fuel to hydrogen. Steam Reforming is complex chemical reaction, mass and heat transfer due to the exothermic methane/air combustion reaction and the endothermic steam reforming reaction. Typically, a steam reformer employs burner to supply appropriate heat for endothermic steam reforming reaction which reduces system efficiency. In this study, the heat of steam reforming reaction is provided by anode-off gas combustion of stationary fuel cell. This paper presents a optimization of heat transfer effect and average temperature of cross-section using two-dimensional models of a coaxial cylindrical reactor, and analysis three-dimensional models of a coaxial cylindrical steam reformer with chemical reaction. Numerical analysis needs to dominant chemical reaction that are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming(DSR) reaction. The major parameters of analysis are temperature, fuel conversion and heat flux in the coaxial reactor.

Study of Solvent Effects in Diels-Alder Reaction through Charge Transfer Formation by Using Semi-empirical Calculations

Mehdi Salih Shihab 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.10

Study of computational model of the concerted Diels-Alder reaction between 9,10-dimethyl anthracene (as donor) and tetracyanoethylene (as acceptor) in absence and in presence of aromatic solvents (benzene, mesitylene and hexamethylbenzene, as donors) using an AM1 semi-empirical method. AM1 method used to study the neutral charge transfer complex models that could be expected between donor and acceptor during the course of the concerted Diels-Alder reaction. Calculated enthalpies of reaction of the charge transfer complexes models showed physical and chemical meaning for explain the effect of aromatic solvents on the kinetic process of concerted Diels-Alder reaction that contains tetracyanoethylene. AM1 method, Neutral charge transfer complex, Concerted Diels-Alder reaction

테레프탈알데하이드의 전자전달 강화효과에 따른 헴 단백질 모방 촉매의 성능 향상 및 이를 이용한 비분리막형 과산화수소 연료전지

전시은,안희연,정용진,Jeon, Sieun,An, Heeyeon,Chung, Yongjin 한국화학공학회 2022 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.60 No.4

Terephthalaldehyde (TPA) is introduced as a cross liker to enhance electron transfer of hemin-based cathodic catalyst consisting of polyethyleneimine (PEI), carbon nanotube (CNT) for hydrogen peroxide reduction reaction (HPRR). In the cyclic voltammetry (CV) test with 10 mM H₂O₂ in phosphate buffer solution (pH 7.4), the current density for HPRR of the suggested catalyst (CNT/PEI/hemin/PEI/TPA) shows 0.2813 mA cm^-2 (at 0.2 V vs. Ag/AgCl), which is 2.43 and 1.87 times of non-cross-linked (CNT/PEI/hemin/PEI) and conventional cross liker (glutaraldehyde, GA) used catalyst (CNT/PEI/hemin/PEI/GA), respectively. In the case of onset potential for HPRR, that of CNT/PEI/hemin/PEI/TPA is observed at 0.544 V, while those of CNT/PEI/hemin/PEI and CNT/PEI/hemin/PEI/GA are 0.511 and 0.471 V, respectively. These results indicate that TPA plays a role in facilitating electron transfer between the electrodes and substrates due to the π-conjugated cross-linking bonds, whereas conventional GA cross-linker increases the overpotential by interrupting electron and mass transfer. Electrochemical impedance spectroscopy (EIS) results also display the same tendency. The charge transfer resistance (R_ct) of CNT/PEI/hemin/PEI/TPA decreases about 6.2% from that of CNT/PEI/hemin/PEI, while CNT/PEI/hemin/PEI/GA shows the highest R_ct. The polarization curve using each catalyst also supports the superiority of TPA cross liker. The maximum power density of CNT/PEI/hemin/PEI/TPA (36.34±1.41 μWcm^-2) is significantly higher than those of CNT/PEI/hemin/PEI (27.87±0.95 μWcm^-2) and CNT/PEI/hemin/PEI/GA (25.57±1.32 μWcm^-2), demonstrating again that the cathode using TPA has the best performance in HPRR.

기업지배구조 개선공시의 시장반응과 산업내 정보전이효과

나영,진동민,임미화 한국회계정책학회 2012 회계와 정책연구 Vol.17 No.3

When firms disclose some information in capital market and consequently the stock price on the both disclosing firms and their competitors in the same industry are affected by the information. It is called 'intra-industry information transfers'. This study has been conducted for the objectives as follows:Firstly, it is to examine whether there is an intra-industry information transfer effect on the corporate governance improvement in Korea stock market. Secondly, it is to investigate empirically what determinants cause the effect if it exists and also to provide comprehensive insights into the corporate governance improvement. The results of the empirical analysis on this research are as follows:Firstly, the competitors' Cumulated Abnormal Returns (CARs) computed by Industry Index Returns irregularly increased or decreased but most of them were statistically significant at the 5% or 1% significance level. These results are the same as the those of the firms that disclose corporate governance improvement. Thus, it is considered that the information transfer effect on the corporate governance improvement Korea stock market may exist in the form of the contagious effect. Secondly, the greater the competitors' largest shareholder ratio is, the smaller the competitors' outside director ratio is, and also the greater the information transfer effect on the corporate governance improvement exists. In particular, it is found that the competitors' largest shareholder ratio and the outside director ratio are the main determinants of the information transfer effects. 본 연구는 기업지배구조 개선공시가 경쟁기업의 주가에 미치는 영향을 정보전이의 관점에서 해석하여 기업지배구조 개선공시의 산업내 정보전이효과를 검정하고, 정보전이효과를 발생시키는 요인에는 어떠한 변수들이 있는지 규명하여 자본시장에서의 기업지배구조 공시효과 및 기업지배구조 등급공시의 효율성에 관한 포괄적인 관점을 제공하는 데 그 목적이 있다. 이에 본 연구에서는 기업지배구조와 기업가치, 정보전이효과에 관한 선행이론을 근거로 하여 두 가지 가설을 전개하였고, 매년 한국기업지배구조원에서 공시되는 기업지배구조 등급공시를 이용하여 표본기업을 선정함으로써 개선공시의 정보효과와 정보전이효과를 분석하였다. 또한 정보전이효과가 발생하는 결정요인에 관하여 추가적으로 분석하였다. 연구결과를 요약하면 다음과 같다. 첫째, 경쟁기업의 초과수익률(AAR)과 누적초과수익률 검정결과, 주식시장에서 기업지배구조 개선공시에 대한 정보전이효과는 개선기업과 비슷한 추이를 보이는 감염효과의 형태로 존재하는 것으로 나타났다. 둘째, 회귀분석을 통하여 정보전이효과의 결정요인을 분석한 결과, 최대주주1인의 지분율과 사외이사비율이 줄어들수록 정보전이효과가 크게 나타난다는 결과를 보였다. 이는 경쟁기업의 최대주주지분율과 사외이사비율이 정보효과를 경쟁기업으로 전이시키는 요인임을 나타내고 있다는 것을 시사하고 있다.