• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.299-304
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• 2016

Characteristics of self-propagating reaction for the preparation of ZnO powder from precursors composed of nitrate and citrate compounds were examined. The ratio of C/N was maintained in range of 0.7~0.8 to initiate the self-propagating reaction between the reducing citrate and oxidizing nitrate groups. The samples were decomposed thermally by using TGA. The sudden decomposition occurred in the range of X > 0.5 in a very short time with a very sharp decrease of mass, indicating that the self-propagating reaction would occur. Friedman, Ozawa-Flynn-Wall and Vyazovkin methods were employed to predict the activation energy, reaction order and frequency factor of the reaction rate in the rate determining step of X < 0.5 range. The activation energy increased with increasing fractional conversion in the range of 46~130 (kJ/min). The reaction order decreased in the range of 2.9~0.9, while the frequency factor increased in the range of 85~278 ($min^{-1}$), respectively, with increasing the rate of temperature increase.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.11
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• pp.95-103
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• 1997

A robust center estimation tecnique of n-fold engineering parts is presented, which use self-organizing neural networks with generating and merging learning for training neural units. To estimate the center of the n-fold engineering parts using neural networks, the segmented boundaries of the interested part are approximated to strainght lines, and the temporal estimated centers by thecosine theorem which formed between the approximaged straight line and the reference point, , are indexed as (.sigma.-.theta.) parameteric vecstors. Then the entries of parametric vectors are fed into self-organizing nerual network. Finally, the center of the n-fold part is extracted by mean of generating and merging learning of the neurons. To accelerate the learning process, neural network uses an adaptive learning rate function to the merging process and a self-adjusting activation to generating process. Simulation results show that the centers of n-fold engineering parts are effectively estimated by proposed technique, though not knowing the error distribution of estimated centers and having less information of boundaries.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1137-1143
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• 2019

Hepatitis E virus (HEV) accounts for 20 million infections in humans worldwide. In most cases, the infections are self-limiting while HEV genotype 1 infection cases may lead to lethal infections in pregnant women (~ 20% fatality). The lack of small animal models has hampered detailed analysis of virus-host interactions and HEV-induced pathology. Here, by employing a recently developed culture-adapted HEV, we demonstrated that methyltransferase, a non-structural protein, strongly inhibits melanoma differentiation-associated gene 5 (MDA5)-mediated activation of type I interferon responses. Compared to uninfected controls, HEV-infected cells display significantly lower levels of $IFN-{\beta}$ promoter activation when assessed by luciferase assay and RT-PCR. HEV genome-wide screening showed that HEV-encoded methyltransferase (MeT) strongly inhibits MDA5-mediated transcriptional activation of $IFN-{\beta}$ and $NF-{\kappa}B$ in a dose-responsive manner whether or not it is expressed in the presence/absence of a tag fused to it. Taken together, current studies clearly demonstrated that HEV MeT is a novel antagonist of MDA5-mediated induction of $IFN-{\beta}$ signaling.

• Journal of The Korean Association For Science Education
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• v.31 no.5
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• pp.758-769
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• 2011

This study was designed to investigate the relations of motivation to related variables, and the motivation by student's variables basically through measure of motivation system about science learning. For this, 496 fourth-grade students and 425 eighth-grade students were required to accomplish a questionnaire on behavioral inhibition/activation system about science learning (SL-BIS/BAS), and self-efficacy. Based on these materials, SLBIS/BAS by student's variables and relations between the system to self-efficacy were analyzed. The result of this study shows the following:First, the sensitivity about SL-BIS in the eighth-grade was higher than in the fourth-grade. But sensitivity about SLBAS and self-efficacy in the eighth-grade was lower than in the fourth-grade Hence, the difference in sensitivity about SL-BIS/BAS agree with difference in motivation. Second, there were low negative correlation with SL-BIS and self-efficacy, and positive correlation with SL-BAS and self-efficacy. In addition, two systems account for 41% of self-efficacy, it showed that SL-BIS/BAS relates to self-efficacy. Through the results of this study, relations of motivation to related variables, and the motivation by student's variables were identified. These results would be helpful for teachers to understand the difference about motivation by students' variables and to make a plan for the appropriate strategies for learners.

• Steel and Composite Structures
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• v.26 no.5
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• pp.573-582
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• 2018

This study develops and numerically verifies an innovative seismically resilient bracing system. The proposed self-centering tension-only brace (SC-TOB) is composed of a tensioning system to provide a self-centering response, a frictional device for energy dissipation, and a high-strength steel cable as a bracing element. It is considered to be an improvement over the traditional self-centering braces in terms of lightness, high bearing capacity, load relief, and double-elongation capacity. In this paper, the mechanics of the system are first described. Governing equations deduced from the developed analytical model to predict the behavior of the system are then provided. The results from a finite element validation confirm that the SC-TOB performs as analytically predicted. Key parameters including the activation displacement and load, the self-centering parameter, and equivalent viscous damping are investigated, and their influences on the system behavior are discussed. Finally, a design procedure considering controlled softening behavior is developed and illustrated through a design example.

• Journal of Agricultural Extension & Community Development
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• v.11 no.1
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• pp.95-110
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• 2004

The purposes of this study were to analyze rural youth's leisure activity and to suggest measures for activation. This study was conducted by review of literature and questionnaire, The data was collected from 1,209 stratified cluster random sampled rural youth who are in middle school and high school. To analyze the data, SPSS/WIN program was employed. The major finding of the study were as follows: 1) About 30% of rural youths had less than 1-2 hours for leisure activity in daily life and more than 8 hours for leisure activity during the weekend, and over 40% of rural youths had no plan for leisure activity. 1) They recognized that leisure activity made them enjoy common life, decrease their stress, and get new experience far self-development, 3) participation in sports, organized-activity and self-directed activity of the middle schools youths were higher compare to youths in high schools, 4) to activate leisure life, rural youths expected to get a) direct support for participating leisure activity expenses(27%), b) develop and diffusion of diverse and interesting leisure programs(23%), and c) securing appropriate leisure facilities(22%).

• Journal of Powder Materials
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• v.25 no.2
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• pp.109-119
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• 2018

The objective of this study is to reveal the sintering mechanism of mixed Ti-6Al-4V powders considering the densification and the homogenization between Ti and Al/V particles. It is found that the addition of master alloy particles into Ti enhances densification by the migration of Al into the Ti matrix prior to the self-diffusion of Ti. However, as Ti particles become coarser, sintering of the powders appears to be retarded due to slower inter-diffusion of the particles due to the reduced surface energies of Ti. Such phenomena are confirmed by a series of dilatometry tests and microstructural analyses in respect to the sintering temperature. Furthermore, the results are also consistent with the predicted activation energies for sintering. The energies are found to have decreased from 299.35 to $135.48kJ{\cdot}mol^{-1}$ by adding the Al/V particles because the activation energy for the diffusion of Al in ${\alpha}-Ti$ ($77kJ{\cdot}mol^{-1}$) is much lower than that of the self-diffusion of ${\alpha}-Ti$. The coarser Ti powders increase the energies from 135.48 to $181.16kJ{\cdot}mol^{-1}$ because the specific surface areas of Ti decrease.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1590-1598
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• 2003

In this paper we have presented the results for viscosity and self-diffusion constants of model systems for four liquid n-alkanes ($C_{12}, C_{20}, C_{32}, and C_{44}$) in a canonical ensemble at several temperatures using molecular dynamics (MD) simulations. The small chains of these n-alkanes are clearly $<{R_{ee}}^2>/6<{R_g}^2>>1$, which leads to the conclusion that the liquid n-alkanes over the whole temperatures considered are far away from the Rouse regime. Calculated viscosity ${\eta}$ and self-diffusion constants D are comparable with experimental results and the temperature dependence of both ${\eta}$ and D is suitably described by the Arrhenius plot. The behavior of both activation energies, $E_{\eta}$ and $E_D$, with increasing chain length indicates that the activation energies approach asymptotic values as n increases to the higher value, which is experimentally observed. Two calculated monomeric friction constants ${\zeta}$ and ${\zeta}_D$ give a correct qualitative trend: decrease with increasing temperature and increase with increasing chain length n. Comparison of the time auto-correlation functions of the end-to-end vector calculated from the Rouse model for n-dodecane ($C_{12}$) at 273 K and for n-tetratetracontane ($C_{44}$) at 473 K with those extracted directly from our MD simulations confirms that the short chain n-alkanes considered in this study are far away from the Rouse regime.

• The Journal of the Korea Contents Association
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• v.17 no.8
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• pp.301-311
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• 2017

The current study investigated whether individual variation in motivational activation would predict the drug-use and interacts with discrete emotions to influence the responses to anti-drug advertisements. Motivational activation tendency indicates an individual's level to approach life-sustaining elements and defend life-threatening stimuli. Discrete emotion represents joy, sadness, and fear elicited by the advertisements. The experiment proceeded using both self-reports and physiological responses with 80 subjects. Results showed that approach motivation activation can be a target for anti-drug advertisements and in order to target individuals higher in approach activation, it is necessary to use the appeal type to elicit positive emotions such as joy.

• The Journal of Korean Physical Therapy
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• v.21 no.3
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• pp.47-52
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• 2009

Purpose: To examine the correlation between the gait speed and muscle activation or foot pressure in stroke patients. Methods: Twenty five functionally ambulant stroke patients (male/female: 15/10, mean age: $57.65\pm2.30$) were enrolled in this study. The patients were asked to walk on a plate at a self-selected and comfortable speed. Three walking trials were obtained and then averaged for data analysis. The gait speed and foot pressure were measured from a RS-Scan system. Activation of the quadriceps femoris muscle and biceps hamstring muscle (%RVC) were recorded using ProComp $Infiniti^{TM}$. Results: There was a significant positive correlation between Hamstring muscle activation (%RVC) and gait speed. The gait speed correlated with the foot pressure of the lateral metatarsal zone (M3-5) in the affected side. There was a correlation between the gait speed and the foot pressure of the lateral metatarsal (M3-5) and heel (medial, lateral) zone in the less-affected side. Conclusion: The gait speed is related to hamstring muscle activation and the characteristics of foot pressure. This information was observed in both the affected and less-affected sides, suggesting that rehabilitation programs should be implemented on both sides.