• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.760-771
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• 2016

The purpose of this study was to examine whether social support produced any mediating effects when needy single mothers' sense of social exclusion affected their own will to escape poverty. The subjects in this study were 376 poor single mothers who resided in the cities of Busan, Gimhae and Yangsan and who were in their 20s to 60s. The findings of the study were as follows: First, the single mothers who lived in poverty were given less social support when they felt more excluded in the dimensions of health, relationships, production, consumption, political participation and housing. Second, the needy single mothers had a more will to escape poverty when more social support was provided and less will to escape poverty when they felt more excluded in the dimensions of health, relationships, production, consumption, political participation and housing. Third, social support produced mediating effects when social exclusion affected the will to escape poverty. The findings of the study suggest that in order to relieve needy single mothers' sense of social exclusion and bolster their will to escape poverty, formal social support from the nation and local community and informal social support from neighbors, friends and relatives should both be strengthened.

• The Journal of the Korea Contents Association
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• v.19 no.12
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• pp.129-140
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• 2019

This study investigated cyber university students' motivation and demotivation in learning English. Data was collected from a survey of 498 students in a general English course at a cyber university located in Seoul. The survey inquired into participants' English learning motivation and demotivation. To analyze the data, frequency analysis, descriptive statistics, t-test, and ANOVA were used. The findings reveal that among the motivation factors ideal L2 self was the main cause of motivation followed by promotion-based instrumentality. Among the demotivation factors the anxiety factor was found to have the highest mean followed by negative investment value for learning English. The statistical analysis of English learning motivation and demotivation according to the participants' characteristics indicates that, in terms of English learning motivation factors, the male participants' ought-to L2 self was significantly higher than that of the females' and the promotion-based instrumentality of the students who are unemployed was higher than those who are employed. Moreover, the younger the students' age, the higher their competitive motivation and promotion-based instrumentality. In terms of English learning demotivation, the female respondents achieved higher scores in the factors of anxiety, passive learning style, and negative investment value for learning English than their male counterparts. In addition, employed students showed higher demotivation in negative investment value for learning English than those without employment. The findings of this research can be used in developing online English programs for cyber university students who possess diverse learning goals.

• Sleep Medicine and Psychophysiology
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• v.14 no.1
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• pp.42-48
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• 2007

Introduction: Detrended fluctuation analysis (DFA) is used as a way of studying nonlinearity of EEG. In this study, DFA is applied on sleep EEG of normal subjects to look into its nonlinearity in terms of EEG channels and sleep stages. Method: Twelve healthy young subjects (age：$23.8{\pm}2.5$ years old, male：female=7：5) have undergone nocturnal polysomnography (nPSG). EEG from nPSG was classified in terms of its channels and sleep stages and was analyzed by DFA. Scaling exponents (SEs) yielded by DFA were compared using linear mixed model analysis. Results: Scaling exponents (SEs) of sleep EEG were distributed around 1 showing long term temporal correlation and self-similarity. SE of C3 channel was bigger than that of O1 channel. As sleep stage progressed from stage 1 to slow wave sleep, SE increased accordingly. SE of stage REM sleep did not show significant difference when compared with that of stage 1 sleep. Conclusion: SEs of Normal sleep EEG showed nonlinear characteristic with scale-free fluctuation, long-range temporal correlation, self-similarity and self-organized criticality. SE from DFA differentiated sleep stages and EEG channels. It can be a useful tool in the research with sleep EEG.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.997-1003
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• 2011

In order to investigate devolatilization characteristics for ashless coal with relatively low ash content and high heating value, an experiment was performed in different bed configurations of TGA and DTF(Drop Tube Furnace) at atmospheric pressure condition. The heating rate was $10^{\circ}C$/min up to $950^{\circ}C$ in TGA, while the temperatures of DTF varied from 500 to $1300^{\circ}C$ in step of $200^{\circ}C$. A weight loss and particle temperature were obtained to determine devolatilization kinetics. The kinetic parameters including an activation energy and pre-exponential factor for ashless coal were obtained using Coats-Redfern method in TGA and single step method in DTF. Furthermore, the devolatilization kinetics of the ashless coal were compared with the results of different kinds of conventional coal such as sub-bituminous and bituminous. The results show that the activation energy of devolatilazation for ashless coal is lower than those of others in fixed and entrained conditions.

• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.535-542
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• 2021

In this study, to improve the interfacial bond strength of cast iron-aluminum dissimilar materials, graphite was removed to a certain depth from the cast iron surface through de-graphitization heat treatment. As the heat treatment time increased, the depth at which graphite was removed increased, showing a linear relationship between the heat treatment time and depth. Aluminum was filled to a certain depth on the de-graphitized cast iron surface through die-casting method, and no intermetallic compounds were formed on the cast iron-aluminum interface. The interfacial bonding strength showed a value of 90 MPa regardless of the heat treatment time, which is very high compared to the 12MPa bonding strength of the material without de-graphitization heat treatment. This result is thought to be due to the mechanical bonding of the undercut structure as the liquid aluminum, penetrated by the high pressure die-casting process, solidified in the de-graphitized region of the cast iron.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.27-35
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• 2005

In this study, a performance analysis code was developed for the off-design performance analysis of air turbo ramjet(ATR) engine, and the analyses were performed for the pre-designed ATR engine at several operating points in the envelope. Variable intake and thrust nozzle were assumed to cover the wide envelope. Mathematical models for each components were developed to calculate their off-design performance. Simple design formulas were introduced for some components to explore the performance variation versus the design parameters. As a result, the pre-defined engine couldn't cover the entire mission profile. And it was also found that the effect of the pre-cooler was not very great, especially in the region of low Mach number.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.243.2-243.2
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• 2010

현재 바이오디젤(Bio diesel)은 유지와 메탄올을 염기촉매를 넣고 전이에스테르화(Trans-esterification)반응하여 생산한다. 생산된 1세대 바이오 디젤은 분자 내 산소가 다량 함유되어 여러 가지 단점을 가지기 때문에 전이에스테르화 반응을 대체한 탈산소(Deoxygenation)반응이 주목 받고 있다. 본 연구에서는 유리지방산(Free fatty acid, FFA)인 올레익 산(Oleic acid)의 탈산소반응을 수행하였다. 하이드로탈사이트(Hydrotalcites) 구조인 MgO-$Al_2O_3$(MgO=70 wt%)를 6시간 동안 $500^{\circ}C$에서 예비소성(Pre-calcination)하여 담체로 사용하였다. 제조된 MgO-$Al_2O_3$ 담체에 함침법(Incipient wetness method)으로 20 wt% Ni을 담지 시켰다. 제조된 Ni/MgO-$Al_2O_3$촉매는 소성온도를 변화시켜 반응 실험을 수행하였다. TPR 분석을 통해 산화-환원특성을 분석하였고 생성물의 원소분석을 통해 생성물의 산소함량을 측정하였다.

• Journal of Science and Technology Studies
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• v.7 no.1
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• pp.33-66
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• 2007

In the post-catchup era, the probability of technology risk are growing according to technology innovation activities with high uncertainty are increasing. Risk acceptance and management are appearing as a more important policy issue. This paper examines the technology risk as a political and social sight and the character of technological risk in the post-catchup era. In the post-catchup, new technology and policy are more undergone trial and err. In particular, we need new approach and policy countermeasures to cope with risky environment and overcome catchup legacy. Accordingly, Korea risk management is needed reshaping of risk management system, increment of risk communication, risk management according to technology type, precautionary approach, bounded trial and err strategy, knowledge accumulation and learning reinforcement.

• Membrane Journal
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• v.16 no.1
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• pp.77-84
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• 2006

Transport mechanisms of nickel ion through a continuous electrodeionization (CEDI) were investigated in terms of electric properties of ion exchange textile (IET). The porous plug model and extended Nernst-Plank (N-P) equation were applied for the description of transport mechanism of nickel ion. The model revealed that the CEDI performance was mainly due to the induced current not accelerated mobility by IET. This study also suggested that optimal operating conditions are attained with minimized electroregeneration region.

• Journal of Korea Technology Innovation Society
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• v.14 no.2
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• pp.157-176
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• 2011

As innovative capabilities of private and public sector in Korea has increased, the innovation system faced with the necessities for transition from imitation oriented approaches to post catch-up approaches. Particularly, public research sector has pressure for the supply of generic technological knowledge from private sector. It needs the transformation of research question setting, organizing research activities and new trajectory for commercialization of research output. This paper analysed the characteristics of post catch-up activities from the case study of Daeduk Innopolis where most of public research institutes are located.