• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.111-116
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• 2014

The kinetics and mechanism of oxidation of sulfanilic acid by N-chloro-p-toluene sulfonamide (chloramine-T) have been studied in acid medium. The species of chloramine-T were analysed on the basis of experimental observations and predominantly reactive species was taken into account for proposition of most plausible reaction mechanism. The derived rate law (1) conforms to such a mechanism. $$-\frac{d[CAT]}{dt}=\frac{kK_1[RNHCl][SA]}{K_1+[H^+]}$$ (1) All kinetic parameters were evaluated. Activation parameters such as energy and entropy of activation were calculated to be $(61.67{\pm}0.47)kJmol^{-1}$ and $(-62.71{\pm}2.48)kJmol^{-1}$ respectively employing Eyring equation.

• Journal of the Korean Ceramic Society
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• 제25권2호
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• pp.136-142
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• 1988

β-Al2O3, which is used for solid electrolyte membrances in sodium-sulfur batteries, was prepared by sol-gel process. Sodium-n-propoxide NaOC3H7 and aluminum-isopropoxide Al(OC3H7)3 were hydrolyzated in the solution at pH 3, pH 7, pH 9 and pH 11, respectively. The sol-gel processed samples were calcined at several temperature steps, respectively and analysed by thermal analyser(DT-TGA), infrared spectrum analyser and X-ray diffraction analyser. The gelling rate of solution at pH 7 was much higher than that of the solution at pH 3. Thermal exchanging behavior of the gels at pH 3 were similar to Na2O·Al2O3·6H2O and, above pH 7, were similar to Na2O·Al2O3·3H2O. When samples' composition ratio was 9.13 : 90.87 [NaOC3H7:Al(OC3H7)3] at pH 7, β-Al2O3 was formed at 1100℃.

• Journal of Ginseng Research
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• 제18권3호
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• pp.196-199
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• 1994

A study was designed to investigate the sorption characteristics of binary mixture of red ginseng powder and maltodextrin(DE-17) or lactose stored at various relative humidities ranging from 52% to 93%. At low relative humilities below RH 67%, the sorption equilibrium was easily achieved, whereas at higher relative humidity values over 75%, all of the mixtures tended to absorb moisture continuously with an increase in storage time. A linear equation of log(dw/dt): a log(t)+ log b was found to be valid between the sorption rate and storage time with respect to storage humilities. A linearity was also found between log(1-Aw) and the amount of water absorbed over the Aw range of 0.52∼0.93 and the slope was affected by the kind of sugar added with that of red ginseng powder and maltodextrin mixture being the smallest.

• Proceedings of the KIPE Conference
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.359-360
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• 2015

10kV IGCT has been recently developed and has the potential to push wind turbine systems to higher power and voltage rating. Converters employing IGCTs need snubber and OVP circuit to limit the rate of rise of current and peak over voltage across IGCT during turn on and off state respectively. The conventional RCD snubber which is used in such power converter dissipates a significant amount of power. In order to reduce the amount of energy lost by conventional RCD snubber, this paper proposes an isolated inductor snubber circuit that not only meets all of the IGCTs characteristics during on and off-state but also significantly saves the power loss. Loss analysis of conventional di/dt snubber and OVP circuit is performed for the 3-level NPC type back-to-back VSC supplied from grid voltage of 6.9kV. In comparison with the conventional snubber, isolated inductor snubber has a fewer number of components and improved efficiency leading to a reliable and efficient wind turbine systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제20권4호
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• pp.2752-2759
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• 1996

This paper presents crack growth analysis approach on the basis of neural networks, a branch of cognitive science to high temperature low cycle fatigue that shows strong nonlinearity in material behavior. As the number of data patterns on crack growth increase, pattern classification occurs well and two point representation scheme with gradient of crack growth curve simulates crack growth rate better than one point representation scheme. Optimal number of learning data exists and excessive number of learning data increases estimated mean error with remarkable learning time J-da/dt relation predicted by neural networks shows that test condition with unlearned data is simulated well within estimated mean error(5%).

• Bulletin of the Korean Chemical Society
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• 제19권4호
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• pp.444-449
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• 1998

The kinetics of the formation of triplex $poly(dA){\cdot}[poly(dT)]_2$ from poly(dA)·poly(dT) and poly(dT) is examined by various optical spectroscopic methods, including absorption, circular and linear dichroism (LD) spectroscopy. In the pseudo first order condition, where the poly(dT) concentration is kept lower than that of duplex, the association of the poly(dT) is enhanced by the presence of ethidium; the rate constant is proportional to the amount of ethidium in the mixture. When the concentration of the duplex and the single strand is the same, a spectral change is explained by double exponential curves, indicating that at least two steps are involved, the fast association and slow rearrangement steps. In contrast to the pseudo first order kinetics, the association step in an equimolar condition is not affected by the presence of ethidium. In the rearrangement step, the magnitude of LD decreases with an increase in ethidium concentration, suggesting that the bending of polynucleotide around the intercalation site occurs in the rearrangement step.

• East Asian mathematical journal
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• 제38권1호
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• pp.65-84
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• 2022

This paper is based on Yanbian University's physical test data, and uses statistical analysis methods to study the relationship between college students' physical test scores to promote college physical education. Firstly, using gender as categorical variables, we conduct a general analysis of students in different majors and different grades, and obtain the advantages and disadvantages of male and female college students; then we use Decision Trees and Random Forest algorithms to conduct modeling analysis to provide valuable suggestions for relevant departments of the university. the aiming of this research analyzing about the undergraduates physical test is that giving universities the targeted suggestions to improve the college graduate rate and promote the overall development of higher education, lay the foundation for achieving universal health.

• International Journal of Knowledge Content Development & Technology
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• 제12권2호
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• pp.77-98
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• 2022

These papers surveyed the respondents' Awareness and perception of Plagiarism among the Faculty members and research scholars of higher educational institutions in Dindigul District, Tamil Nadu. The 500 questionnaires were distributed among the participants, 456 questionnaires were filled and returned for usable by the respondents and remaining not replied. The responses rate is 91.2%. Further among 222 Male re- spondents, 11.18% of them are having Aware, 10.75% of them in Learning, 10.53% are with Fair and 76(16.23%) of them are Expert. Similarly out of 234 Female respondents, 16.45% of them has No Idea, 7.02% of them have Aware, 10.09% of them in Learning, 8.99% are with Fair and 8.77% of them are Expert.

• Journal of the korean academy of Pediatric Dentistry
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• 제24권3호
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• pp.610-627
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• 1997

The purpose of this study was to compare the caries activity and cariogenic factors in children in different residence areas. The subjects of the study were 268 kindergarten children who were selected from the downtown area(D), apartment area(A), suburban area(S), and rural area(R) in and around the city of Iksan, Korea. Caries activity was measured as past caries experience (dft index and dfs index) and salivary reductase activity (Resazurin Disc Test scores). Cariogenic factors were investigated by a questionnaire. The results were as follows: Reductase activity S > R > D > A dt index R, S > D, A ft index D - the highest dft index A - the lowest ds index R - the highest fs index D - the highest Toothbrushing frequency A - the highest, R - the lowest Toothbrushing before bed D, A > S, R Toothbrushing by parents S, R > A, D Sweets intake freqeuncy A - the highest, S - the lowest Distance to dental office D < A < S < R Dental treatment experience D - the highest, A - the lowest Flouride application rate D > S > R > A Sealant application rate D > A, S > R Birth order A, S > R, D Age D > S > R, A

• Transactions of the Korean Society of Mechanical Engineers A
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• 제29권7호
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• pp.983-989
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• 2005

The effects of mechanical parameters on the characteristics of chemical mechanical polishing(CMP) can be directly evaluated by friction force. The piezoelectric quartz sensor for friction force measurement was installed, and friction force could be detected during CMP process. Furthermore, friction energy can be calculated by multiplying relative velocity by integration of the friction force throughout the polishing time. $SiO_2$ slurry for interlayer dielectric(ILD) CMP was used in this experiment to consider the relation of frictional characteristics and polishing results. From this experiment, it is proven that the friction energy is an essential factor of removal rate. Also, the friction force is related to removal amount per unit length(dH/ds) and friction energy has corelation to the removal rate(dH/dt) and process temporature. Moreover, within wafer non-unifornity(WIWNU) is related to coefficient of friction because of the mechanical moment equilibrium. Therefore, the prediction of polishing result would be possible by measuring friction force.