• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.581-587
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• 1988

The solvolysis of substituted benzyl bromides was studied in binary solvent mixtures of acetone-water and ethanol-water at $25^{\circ}C$ and $45^{\circ}C$. The rate constants increase with electron-donating substituents in benzene ring and increasing of water contents in both of solvent mixtures. The sensitivity parameter (m) of the solvolysis of substituted benzyl bromides to solvent ionizing power (Y) was decreased in going from the electron-donating group to electron-withdrawing one, whereas their nucleophilic sensitivity increased continuously in going to above same substituents. It was shown that electron-donating (electron-withdrawing) groups make the transition state looser (tighter). The above results were consisted with the account for the potential energy surface model and the quantum mechanical approach.

• School Mathematics
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• v.16 no.4
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• pp.727-743
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• 2014

The concepts of sample and sampling are central to the statistical thinking and foundations of the statistical literacy, so we need to be emphasized their importance in the statistics education. However, many researches which dealt with samples only analyze textbooks or students' responses. In this study, the concept of sample is addressed by a historical consideration which is one aspect of the didactical analysis. Moreover, developing concept of sample is analyzed from the preceding studies about the statistical literacy, considering the sample representativeness and the sampling variability. The results say that the historical process of developing the concept of sample can be divided into three step: understanding the sample representativeness; appearing the sample variance; recognizing the sampling variability. Above all, it is important to aware and control the sampling variability, but many related researches might not consider sample variability. Therefore, it implies that the awareness and control of sampling variability are needed to reflect to the teaching-learing of sample for developing the students' statistical literacy.

• Journal of the Korean Chemical Society
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• v.22 no.6
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• pp.417-422
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• 1978

Rather than undergo photooxygenation, the Z-configuration benzalpyrrolinones (Z-2, Z-4) photoisomerized to the E-configuration isomers under direct or sensitized irradiation. Rose bengal sensitized photochemical stereoisomerzation of benzalpyrrolinones (Z-2, Z-4 and E-2) with monochromatic light (at 557 nm, excitation of rose bengal only) showed that the triplet of benzalpyrrolinones was involved in the photoisomerization, since oxygen inhibited the photoisomerization.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.337-341
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• 2005

This paper reports the study on coking rate and carbon formation route as a function of reaction temperature using the Ni catalysts in the $CO_2$ reforming of methane. In this paper, carbon deposition on catalysts and its kinetics during reforming reaction were studied by using a thermogravimetric analyzer. Kinetic studies show that reaction orders of carbon formation obtained 1.33 ($CH_4$) and -0.52 ($CO_2$) by experiments on partial pressure of reactant gas, respectively. On the basis of model equation, the kinetic parameters for the coking reaction at different temperatures indicated that methane decomposition dominated carbon formation at lower temperatures ($<600^{\circ}C$), while $CH_4$decomposition and Boudouard reactions become significant for coking in the temperature range of $600{\sim}700^{\circ}C$.

• Applied Chemistry for Engineering
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• v.2 no.1
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• pp.77-85
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• 1991

A series of samples having different $SiO_2/Al_2O_3$ ratio were prepared by treating hydrogen mordenites with boiling hydrochloric acid and with hydrofluoric acid. The acidities of these samples were measured by TPD of $NH_3$ and by pyridine adsorption using IR, and the catalytic activities and selectivities of isomerization were measured for the reaction of ortho-xylene. For the samples treated by boiling hydrochloric acid, the acidities decreased with the increasing $SiO_2/Al_2O_3$ ratio caused by the extraction of framework aluminum. The sample having the $SiO_2/Al_2O_3$ ratio or 22 showed better activity than the others. For the samples treated by hydrofluoric acid, the content of chemically binding fluorine increased with the increasing contact time of hydrofluoric acid solution. The catalytic activities decreased with the hydrofluoric acid treatment due to the decreased acid sites resulted from the extraction of aluminum and silicon as well as the hydroxyl group replacement by the fluoride ion. The slightly increasing catalytic activities, however, came from the newly created acid sites, due to the removal of surface silicon, having enhanced by the inductive effect of binding fluorin with further acid treatment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.175-185
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• 2020

Mobile shopping has been settled down as one of the general shopping methods, good enough to be called new normal today. Contrary to the initial stage for researching the shopping in online environment, the factors more important today must be changed quite a lot. Thus, this study aimed to select the service quality factors regarded as important in mobile shopping, to examine their effects on consumers' rational-emotional evaluation, and also to understand a series of influence relations led to the purchase intention and word of mouth effect in the future, and then obtained the significant results. In the results of this study, only the Personalization and responsiveness of service quality had positive(+) effects on the consumer sentiment, and the consumer sentiment had positive(+) effects on the consumer behavior. Such results verified that the Personalization and responsiveness would be important factors to consumers. Also, when the consumer satisfaction is high, the consumer behavior would be positive too.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.213-216
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• 2009

WGS(Water Gas Shift)반응은 일산화탄소(CO)를 이산화탄소($CO_2$)로 전환하는 반응으로 일체형 수소생산시스템의 실현을 위한 고순도 수소생산에 있어서 중요한 단계이다. WGS 반응은 열역학적 평형을 고려하여 고온전이반응(HTS: High Temperature Shift)과 저온전이반응(LTS: Low Temperature Shift) 두 단계 반응으로 진행된다. 두 단계 공정의 통합을 위해 낮은 온도에서 높은 활성을 갖는 WGS 반응용 촉매 개발이 필요하다. 최근 낮은 온도에서 높은 활성을 갖는 귀금속 촉매에 다양한 담체를 적용시킨 연구가 활발히 진행되고 있다. 선행 연구 결과, Ce-$ZrO_2$ 구조는 Ce/Zr 비에 따라 다양한 특성 변화를 관찰하였다. 따라서 낮은 온도에서 높은 활성을 갖는 WGS 반응용 촉매 제조를 위해 환원성 담체인 $CeZrO_2$에 Pt 을 담지시켜 성능을 평가하였다. 제조된 모든 담체는 공침법(Co-precipitation)으로 제조 하였으며 $500^{\circ}C$에서 6시간 소성하였다. 제조된 담체에 백금(Pt)을 함침법(Incipient Wetness Impregnate)으로 담지시켰다. 특성분석은 BET를 이용하여 표면적을 측정하였다. 촉매 반응 실험조건은 $200^{\circ}C{\sim}400^{\circ}C$ 온도범위에서 기체공간속도(GHSV: Gas Hourly Space Velocity) 45,000 ml/$h{\cdot}g-cat$ 으로 혼합가스($H_2$:60%, $N_2$:20%,$CH_4$:1%,CO:9%,$CO_2$:10%)를 흘려 반응 후 배출되는 가스를 Micro-Gas Chromatography 를 이용하여 측정하였다.

• KSBB Journal
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• v.22 no.5
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• pp.345-350
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• 2007

Phosphosugars are found in all living organisms and are commercially valuable compounds with possible applications in the development of a wide range of specialty chemicals and medicines. In carbohydrate metabolism, fructose 6-phosphate (F6P) is an essential intermediate formed by phosphorylation of 6' position of fructose in glycolysis, gluconeogenesis, pentose phosphate pathway and Calvin cycle. In glycolysis, F6P lies within the glycolysis metabolic pathway and is produced by isomerisation of glucose 6-phosphate. For large-scale production, F6P could be produced from starch using many enzymes such as pullulanase, starch phosphorylase, isomerase and mutase. In enzymatic reactions carried out at high temperatures, the solubility of starch is increased and microbial contamination is minimized. Thus, thermophile-derived enzymes are preferred over mesophile-derived enzymes for industrial applications using starch. Recently, we reported the production of glucose 1-phosphate (G1P) from starch by Thermus caldophilus GK24 enzymes. Here we report the production of F6P from starch through three steps; from starch to glucose 1-phosphate (glucan phosphorylase, GP), then glucose 6-phosphate (phosphoglucomutase, GM) and then F6P (phosphoglucoisomerase, GI). Using 200 L of 1.2% soluble starch solution in potassium phosphate buffer, 1,253 g of G1P were produced. Then, 30% yields of F6P were attained at the optimum reaction conditions of GM : G1 (1 : 2.3), 63.5$^{\circ}C$, and pH 6.85. The optimum conditions were found by response surface methodology and the theoretical values were confirmed by the experiments. The optimum starch concentrations were 20 g/L under the given conditions.

• KSBB Journal
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• v.10 no.3
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• pp.283-291
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• 1995

The characteristics of aminopeptidase M(ApM) immobilized covalently on Cellufine Formyl and the continuous production of authentic human growth hormone(hGH) from methionyl human growth hormono(met-hGH) using the column reactor packed with immobilized ApM were investigated. Immobilized ApM with the proportion of 2.3mg ApM per 1g Cellufine Formyl gel had the highest met-hGH conversion activity. The optimum pH(7.0) and temperature($55^{\circ}C$) showed no appreciable difference between free and immobilized enzymes and the optimum temperature in continuous operation of the column reactor was also found to be $55^{\circ}C$. Under the conditions at which met-hGH was converted completely to hGH, the yield and productivity were about 77% and 0.8mg hGH/ml$.$h, respectively. In two column reactors of different sizes, met-hGH was converted to hGH with the same conversion rates and hGH yields at the same space velocities. The half-life of the reactor systems at $45^{\circ}C$ and $55^{\circ}C$ were projected from the continuous operations for 90 days to be 225 days and 81 days, respectively.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.131-136
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• 2023

We developed a method to measure the concentration of highly concentrated colored samples using color coordinates. We present a color analysis to estimate the concentration of highly concentrated binary solutions with an empirical function and apply it to estimate the kinetics of a catalytic irreversible reaction of resazurin to resorufin. The developed method enabled one to measure the concentration of solutions whose range of concentrations is nonlinear and beyond the limit of UV-vis spectroscopic measurement directly without dilution.