• Journal of the Korean Electrochemical Society
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• v.19 no.1
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• pp.1-8
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• 2016

Capacity of layered lithium nickel-cobalt-manganese oxide ($LiNi_{1-x-y}Co_xMn_yO_2$) cathode material can increase by raising the charge cut-off voltage above 4.3 V vs. $Li/Li^+$, but it is limited due to anodic instability of conventional electrolyte. We have been screening and evaluating various sulfone-based compounds of dimethyl sulfone (DMS), diethyl sulfone (DES), ethyl methyl sulfone (EMS) as electrolyte additives for high-voltage applications. Here we report improved cycling performance of $LiNi_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode by the use of dimethyl sulfone (DMS) additive under an aggressive charge condition of 4.6 V, compared to that in conventional electrolyte, and cathode-electrolyte interfacial reaction behavior. The cathode with DMS delivered discharge capacities of $198-173mAhg^{-1}$ over 50 cycles and capacity retention of 84%. Surface analysis results indicate that DMS induces to form a surface protective film at the cathode and inhibit metal-dissolution, which is correlated to improved high-voltage cycling performance.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.697-708
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• 1992

Liquid Chromatographic behavior of Ni(II) in Isonitrosoethylacetoacetate Imine(IEAA-NR), Ni(IEAA-NH)(IEAA-NR)(R = H, CH_3, C-2H_5, n-C_4H_9, C_6H_5-CH_2) chelates were investigated by reversed-phase HPLC on Micropak MCH-5 column using methanol/water as mobile phase. The optimum conditions for the separation of Ni(IEAA-NH)(IEAA-NR) chelates were examined with respect to the effect of the flow rate, sample solvent, mobile phase strength and column temperature. It was fo$und that metal chelates were properly eluted in an acceptable range of capacity factor value(0{\le}logk'{\le}1). The dependence of the logarithm of capacity factor (k') on the volume fraction of water in the binary mobile phase as well as on the liquid-liquid extraction distribution ratio (Dc) in methanol-water/n-alkane extraction system showed the good linearties, and the dependence of the logarithm of capacity factor (k') on the column temperature and on the enthalpy exhibited the good linearties, and the compensation temperature ({\beta}) from the slope was 773.47{\circ}K. It was suggested that the retention of metal chelates was largely affected by the hydrophobic effect.

• Journal of Christian Education in Korea
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• v.61
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• pp.81-107
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• 2020

This study reviews Bandura's vicarious reinforcement in observational learning process and implies this concept into Christian education in terms of spiritual role modeling. The first part of this study answers three questions: "what is vicarious reinforcement?" "how does vicarious reinforcement take place in observational learning?" and "how does vicarious reinforcement affect observer's behavior change?" Bandura conceptualizes the learning process with observational learning and imitative or non-imitative performance. Based on this concept, Bandura define the roles of vicarious reinforcement in the four steps of observational learning process: attention, retention, motor reproduction, and motivational process. Also, the three effects of vicarious reinforcements are explained in the following categories: the observational learning effect, inhibitory or disinhibitory effects, and eliciting effect. Adapting the structure of observational learning theory in terms of the effect of vicarious reinforcement and the function of role models, the second part of this study examines the biblical concept of imitation of Christ and the modeling strategy of discipleship. Especially Paul's spiritual role model serves as positive vicarious reinforcement for the Christian believers to perform the desired behaviors. Also, Paul's condemnation serves as explicit negative vicarious reinforcement. Then, the last part of this study covers the implication of these findings from observational learning and empirical studies in terms of spiritual role modeling to Christian education.

• Journal of Distribution Science
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• v.13 no.10
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• pp.101-108
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• 2015

Purpose - The convenience store business sector in South Korea has contributed to economic growth and job creation, and the growth potential of this market segment remains very high. In addition, service value is a more important factor than price in determining purchase intention. Research in the convenience store market is relatively very low compared to other retail sectors. In particular, research on service quality for the convenience of retailers who examine and analyze customer behavior and service quality factors used in the convenience store side of the situation is very inadequate. We have investigated the relationship of store service quality, service satisfaction, and store loyalty. In addition, we have examined the way service value moderates the relationship among these variables. Research design, data, and methodology - The questionnaire was developed using modified and supplementary questions based on the KD-SQS and RSQS models. The study suggested a theoretical model composed of 15 hypotheses on the relations between theoretic variables, and surveys conducted with consumers in discount stores in the Seoul and Gyunggi Metropolitan area in order to verify the hypotheses. We used the SPSS/PC statistical packages to analyze the results. The number of surveys used was 227. Moreover, a structural equating model was also used to analyze the reliability and validity of the composing elements and to verify the suggested hypotheses. Results - The overall results of this study are as follows. First, all service quality elements have a significant effect on service satisfaction. Second, all service quality elements have a significant effect on store loyalty. Third, service satisfaction has a significant effect on store loyalty. Finally, when the participants were divided into high and low service value the results of the multiple regression analyses showed that only the relationship between policy of service quality and satisfaction, and human interaction and policy of service quality and loyalty were significant. The implications are discussed based on the findings of the study. Conclusions - First, through direct hypotheses testing, we confirmed that the convenience service quality positively impacts the service satisfaction and loyalty of buyers. In particular, the reliability, origin benefit, and promotion were found to have more influence on satisfaction and loyalty of consumers of a convenience store. Further, for the service quality of the convenience for the consumer loyalty, greater human interaction was a high-value and statistically significantly higher than the degree of improvement in consumer loyalty. This underscores the importance of education and human services management of employees working in a convenience store. In particular, frequent changes in personnel generate results that negatively impact loyalty with customers. These results may lead to a serious problem in the economics of the store. Therefore, it should enhance the value of services through the establishment of training and compensation for employees. In addition, a certain educational level is required as well as a basis for compensation and retention.

• Analytical Science and Technology
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• v.15 no.4
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• pp.329-334
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• 2002

Tributyl phosphate(TBP) is used in solvent extraction process for radioactive waste. This compound may be degraded to dibutyl phosphate($DBP^-$), monobutyl phosphate($MBP^{2-}$) and ${PO_4}^{3-}$ by radioactive material. Amount of $DBP^-$ and $MBP^{2-}$ in TBP must be monitored because they production of these compounds means degradation of which leads to a decrease in the extraction yield. Retention behavior for $DBP^-$, $MBP^{2-}$, $F^-$, $Cl^-$, ${NO_2}^-$, ${NO_3}^-$, ${SO_4}^{2-}$ and ${PO_4}^{3-}$ are studied with AS4A-SC(Dionex) analytical column and $Na_2CO_3$/NaOH eluent by Ion chromatography. Optimum condition for these anions is 2 mM $Na_2CO_3$/1 mM NaOH eluent. All anions by this condition is well separated within 15min. Dynamic range is $10{\mu}g/mL$ - $100{\mu}g/mL$ for DBP and $5{\mu}g/mL$ - $50{\mu}g/mL$ for $MBP^{2-}$, respectively. The Detection limit for AS4A-SC are $1{\mu}g/mL$ for $DBP^-$ and $0.5{\mu}g/mL$ for $MBP^{2-}$ in this system with a $25{\mu}L$ sample loop.

• Analytical Science and Technology
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• v.18 no.3
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• pp.201-205
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• 2005

Tri-octyl amine (TOA) is used in solvent extraction process for radioactive waste. This compound may be degraded to di-octyl amine (DOA), mono-octyl amine (MOA) by radioactive materials. Amount of TOA, DOA and MOA in TOA must be monitored because they production of these compounds means degradation of which leads to a decrease in the extraction yield. Retention behavior for TOA, DOA and MOA are studied with Phenomenex LUNA-$C_{18}$ ($4.6mm{\times}25cm$) analytical column and $CH_3OH:H_2O$ (50 mmol $CH_3COONH_4$) eluent by liquid chromatography. Optimum condition for these compounds is $CH_3OH:H_2O$ (50 mmol $CH_3COONH_4$) = 85 : 15 ratio. TOA, DOA and MOA compounds is well separated within 20 minute. Dynamic range is $30{\sim}160{\mu}g/mL$ for TOA, $5{\sim}100{\mu}g/mL$ for DOA and $0.1{\sim}5{\mu}g/mL$ for MOA, respectively. The detection limit are $0.1{\mu}g/mL$ for TOA, $1{\mu}g/mL$ for DOA (in SCAN mode) and $0.1{\mu}g/mL$ for MOA (in SIM mode) in this system with $20{\mu}L$ sample loop.

• Journal of Educational Research in Mathematics
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• v.9 no.1
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• pp.351-367
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• 1999

This study aims to study the discourses influencing high school students' concept and attitude toward mathematics, and to examine how gender differences concerning mathematical aptitude are created. This study is based on the results of previous two studies which suggested that mathematical competence differs not only according to gender, region and school year, but also even within the same gender. For this study, 12 students ranking in the top 10% at two co-ed high schools were interviewed to find out 1) what discourses are related to gender and mathematics, 2) in what way these discourses are formulated and gain currency, and 3) how they have affected students in general. Common notions concerning mathematics may be summed up as follows: 1) Most of the students believe that gender difference in mathematical aptitude results because biologically men tend to be strong in mathematics and analytical skills while women tend to have better linguistic ability. This concept can help male students' studying to have a greater learning toward mathematics. 2) A large number of the students believe that male students' studying method is based on comprehension whereas female students' method is based on retention, and hence the former group tends to be better at applying their learning than the latter group. This notion seres to encourage male students and discourage female students from tackling difficult mathematical problems. 3) Many students believe that, although female students may surpass their male counterparts in middle school or the first year of high school, they will eventually fall behind by the 3rd year. Despite research which shows that these common beliefs are not grounded in scientific proof, high-school girls, who may be strong in mathematics, lose self-confidence and feel a sense of crisis. The mechanisms which produce and reinforce such concepts as those mentioned above can be summarized as follows: 1) Regarding the choice of majors and future career paths, parents show different attitudes toward sons and daughters, and this tends to influence high-school girls and hinders them from entering mathematics-related fields. 2) Teachers with value systems based on stereo-typed gender roles affect students a great deal, and give different advice according to gender of their students, for selecting their major fields - for instance, whether to study the natural sciences as opposed to humanities. 3) This study indicates that peer-group behavior, of either support or exclusion, also reinforces the process of internalizing notions of gender difference related to mathematical aptitude. 4) The gender-based notion that men are naturally more inclined to have better mathematical ability has caused male students to choose the natural science subjects and female students to turn to the humanities. The discourses discussed above, propagated in schools and homes, and in the mass media, are continually reinforced along with general gender inequalities in the society at large.

• Food Science and Preservation
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• v.11 no.4
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• pp.496-502
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• 2004

Purified acorn starch was obtained from alkali precipitation method. Acorn amylose and acorn amylopectin were fractionated from purified acorn starch by butanol improvement method. Gel permeation chromatography (GPC) was used to measure molecular weight distribution of acorn starch, acorn amylose, acorn amylopectin and corn starch, corn amylose, corn amylopectin. GPC measurement diagrams were obtained by each retention time. And then, we used DMSO and DMF as solvent, pullulan as standard material. We calculated the Number-average molar mass (Mn), Weight-average molar mass (Mw) and polydispersity from molecular weight distribution of each sample. As a result of estimating molecular weight using GPC, Mw of amylose has small value than Mw of amylopectin. From this fact, the molecular structural aspects of amylose and amylopectin were predicted and it was in good agrement with the tendency of polydispersity by GPC. The polydispersity of starch had big value than amylose and amylopectin, from this result, it might be known that the range of molecular weight appeared broad by heterogeneous properties of two components. The viscosity of purified acorn starch, amylose, amylopectin seperated from acorn starch, was decreased by increasing the shear rate and raising the temperature exponentially. Acorn starch solutions exhibited pseudoplastic power law fluid behavior.

• Clean Technology
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• v.23 no.2
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• pp.163-171
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• 2017

Currently, researches on recycling and reuse of waste energetic materials have recently gained a great attention from advanced countries due to ever tightening environmental regulations. In this study, as a part of a recycling technology, the experiments and dynamic simulation of simulated moving bed (SMB) process were performed to efficiently separate TNT and RDX from their mixture, which are main components of ammunition. In order to determine the operation zone of SMB process, the retention times of TNT and RDX were measured using HPLC at different flow rates and the adsorption equilibrium of each component was obtained by using a moment method. According to the adsorption equilibrium and the triangle theory of SMB process, four operation points were determined and separation experiments were carried out by the SMB process using the solvent consisting of acetonitrile and water. Two different mixing ratios (6:4 and 1:1) of acetonitrile and water were chosen for the experiment due to the great impact of mixing ratio of the solvent on separation. The performance of SMB process was evaluated by purity, recovery, productivity and solvent consumption. Pure TNT and RDX were successfully obtained from the SMB process and the dynamic simulation for the SMB process agreed well with the experimental results. Therefore, the dynamic model could be applied for predicting the dynamic behavior of the SMB process and designing a large scale SMB process.

• Nuclear Engineering and Technology
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• v.20 no.2
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• pp.105-111
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• 1988

The chemical effects resulting from the capture of the thermal neutron by manganese in various crystalline permanganates, that is, potassium permanganate ammonium permangante and barium permanganate, have been investigated. The effect of pH of solvent on the distribution of radioactive manganese chemical species, that is, cationic $^{56}$ Mn, $^{56}$ MnO$_2$ and $^{56}$ MnO$_4$$^{[-10]}$ produced in the permanganates by $^{55}$ Mn(n, ｒ) $^{56}$ Mn reaction was studied by using various adsorbents and ion-exchanger, that is, zeolite A-3, kaolinite, alumina, manganese dioxide and Dowex-50 The distribution of radioactive MnO$_4$$^{[-10]}$ in kaolinite and alumina has higher than that in other adsorbents and ion-exchanger at a representative pH value of 4, 7 and 9, respectively. The yield of radioactive MnO$_4$$^{[-10]}$ is higher at pH 4 End pH 9 than at pH 7. The thermal annealing behavior of recoil manganese atoms produced in the permanganates by $^{55}$ Mn(n, ｒ) $^{56}$ Mn reaction was also studied. The retention of MnO$_4$$^{[-10]}$ in the thermal annealing is increased as annealing temperature increases when it was treated at 10$0^{\circ}C$ and 13$0^{\circ}C$. The recoil effect of permanganates was explained by the hot zone model.