• ETRI Journal
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• v.28 no.4
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• pp.537-540
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• 2006

When multiple ZigBee wireless personal area networks (WPANs) are in close proximity to each other, contentions and collisions in transmissions will lead to increased packet delays. However, there is no existing study on how delay performance would be affected in a crowded real-life environment where each person walking down a busy street would be wearing a ZigBee WPAN. This letter studies the use of ZigBee WPANs in such a real-life environment for real-time heart beat monitoring. To be pragmatic, we derived a mobility pattern from the analysis of a real-life video trace. Then, we estimated the delay performance from the video trace by combining data collected from ZigBee experiments. The results show that the 300 ms packet delay requirement will not be met for only 11% of the time. When failure occurs, it will last for an average duration of 1.4 s.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.115-118
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• 2009

Life time and number of use of liquid propellant rocket engine (LRE) should be carefully defined since those are crucial parameters affecting development costs and period. The present study surveyed the development and qualification records of LRE for space launch vehicles, especially concerning about test numbers and duration. It was shown that a single engine for expendable launch vehicle is tested with tens of ignition and several times duration of flight at least.

• Journal of the Korean Home Economics Association
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• v.33 no.4
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• pp.129-147
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• 1995

The purpose of this study was to empirically verify the influence of sociodemographic and psychologicl variables on time management strategy and time management strategy on home management behavior and family life satisfaction of employed wives, and to provide the information of enhancing the level of family welfare. The monthly income of employed wives was high, as the level of education and time conflict are high, their use of time management strategy is high. The wives who show the high scores on time planning strategy have the effective home management behavior. Also, the score on division of household works strategy of employed wives was high, their satisfaction score on their family lives was high.

• Journal of the Korean Home Economics Association
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• v.35 no.6
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• pp.111-125
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• 1997

The purposes of this study were to analyze the work and leisure of rural couples in Chonnam district, to examine couple's perception about farm life, to analyze the factors influencing the time use of husbands and wives. 300 farmhouses were selected by stratified sampling from 20 Myon in Chonnam district, 244 husbands and 283 wives were interviewed using questionnaire and time diary. The major results are as follow : 1) The rural couples have not pride on agriculture, the level of satisfaction and policy reliability was low, and impoverished conditions was high. 2) work time of wives was two hours longer did, and leisure time of wives was 73 minutes shorter than their husbands. 3) The time use of husbands and wives were significantly influenced by agricultural type, farmwork, house work time, age etc.

• Survey Research
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• v.9 no.1
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• pp.43-68
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• 2008

This study compares two instruments for time use study: The time diary and the Experience Sampling Method (ESM), While previous studies show that the ESM and the full-diary are similar with respect to aggregate estimates, No previous study has examined the concordance rates of individual records from both instruments. Based on the subsamples who completed both instruments during the same time period from 500 family studies conducted by the Alfred P. Sloan Center on Parents, Children, and Work at the University of Chicago, we systematically compares the two instruments and evaluates their relative strengths. The results suggest that time diaries provide less biased time use estimates. and that compared to the time diary, the ESM provides a more detailed description of everyday life. The implications of further researches are discussed.

• Human Ecology Research
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• v.58 no.3
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• pp.447-461
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• 2020

This study explores how the COVID-19 pandemic has changed family life and relationships as well as how these changes affect perceived stress among married men and women. This study investigated changes in family time use, household work, child care, leisure activities, income and expenditures along with relationships between spouses and children using a sample of 627 married persons surveyed online from May 19 to 25, 2020. The results showed that the amount of time spent on household work, child care, and family leisure have increased and that the perceived burden of household work and child care has also increased. Gender differences were found in time use, household work, and child care. Leisure activities have changed toward more time watching TV or online media and playing online games and less time on outdoor activities, shopping, and meeting friends. About 38% of respondents reported a reduction in household income and 22% reported an increase in household debt. The majority experienced no change in the quality of relationships with spouses and children, approximately 20% of the sample reported a positive change in relationships with spouses and children. The findings of multivariate regression indicated that change in work time, negative change in household economy, negative change in household work and negative change in relationships with spouses were associated with marital stress. However, this study found that negative changes in child care and in relationships with children did not affect stress among married parents with children in elementary or secondary school.

• Journal of Environmental Health Sciences
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• v.44 no.6
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• pp.608-617
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• 2018

Objectives: The purpose of this study was to analyze related factors in relation to usage of illicit substances for Korean adolescents. Methods: This was a cross-sectional study, which used data from the Twelfth Korean Youth Risk Behavior Web-based Survey (KYRBWS). A total of 65,528 students in 2016 were included in this study. Chi-square test and logistic regression analysis were used for analyzing related factors using illicit substances. Results: Overall, 553 (0.8%) students responded as having ever used illicit substances during their lifetime and 133 (0.2%) students responded as current illicit substance users. It was found that electronic cigarette (EC) use, conventional cigarette smoking, second hand smoking, sad/despair mood, and economic status were significantly associated factors with usage of illicit substances. Comparing 'current EC users' with 'never EC users', the adjusted odds ratios (OR) was 7.76 (95% confidence interval (CI): 5.56-10.82) for life-time use of illicit substances, and 18.74 (95% CI: 8.01-43.87) for current use of illicit substances among adolescents. Additionally, comparing 'students who ever were exposed to second hand smoking during the past week', with 'students who never were exposed to second hand smoking', the adjusted OR was 2.60 (95% CI: 2.13-3.17) for life-time use of illicit substances, and 2.85 (95% CI: 1.68-4.83) for current use of illicit substances among adolescents. Conclusions: Based on the results, electronic cigarette use, second hand smoking, conventional cigarette smoking, sad/despair mood, and economic status were significantly associated with increased odds of substance experience and current substance use. Therefore, the results of this study can provide a useful evidence about adolescent behaviors in predicting substance use.

• Journal of the Korean Home Economics Association
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• v.28 no.3
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• pp.33-52
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• 1990

The aims of this study are to classify the life styles of urban housewives, to see their relationship between life style and demorgaphic variables, and also to see the relationship between life style and dietary patterns. This study has been performed by a questionsire about life style, demographic variables and dietary pattern. The selected samples were 475 housewives. The data were analyzed by factor analysis, cluster analysis, Duncan test, X-test and F-test. Life style is classified into 4 types: temporary enjoying type, passive irrational type, realistic conservative type, actual progressive type. The housewives who are in temporary enjoying type usually do randomly and don't think seriously something. And they have tendency to enjoy themselves. Therefore they don't have any plan for dietary behavior. The passive irrational type's housewives have no consistancy in their life and they do everything temporarily. The housewives who are in this type have relatively low incom, low level of education and they are high in age. The people who are in realistic conservative type act reasonably and elastically everything. They use convenient food very much, because they are willing to save time to make them. The housewives who are included in actual progressive type are well organized and planned in dietary behavior than others, when they dine out, they eat with family together in general, they usually use only a kind of western sauces and convenient food. They are relatively young, highly educated, and they are high income group. In conclusion realistic conservative type and actual progressive type are both relatively desirable type in dietary behavior, but in temporary enjoying type and passive irrational type, there, have to do some guide and education about managing family resources and dietary behavior.

• Journal of Korean Elementary Science Education
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• v.20 no.1
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• pp.45-57
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• 2001

The purpose of this study is to guide and apply gettable and accessible materials around everyday life into classroom instruction, and to find out their effects on student academic achievement. In order to achieve it, this study was tried to develop and guide available materials around life in teaming activities, to provide a preliminary assignment that could apply the available materials, and to compare its academic achievement to one from field trip loaming. For the hypothesis testing, first, the experimental and comparing classes were selected based on the results of basic learning diagnostic evaluation, which conducted by the researcher being served as a full-time science teacher of the third and sixth grade of K elementary school in Kwangju for 2 years. Secondly, the instructional use of the available materials around life was applied to the experimental class. Also, the instructional use of the existing materials was applied to the comparing class. Finally, for the testing of the effects on academic achievement, the posterio test was implemented after conducting the experimental instruction in knowledge·understanding, inquiry process, and attitude domains classified by the unit characteristics. Using SPSS/WIN program the t-test was performed in order to compare the differences between the two groups. Major findings were as follows: 1) In the achievement test of knowledge·understanding domain, there were no significant differences at the 5％ level between the experimental and comparing classes. It could be difficult to say, therefore, that the instructional use of the available materials around life was more effective than the instructional use of the existing materials. However, it had some effects on differences between the third grade final achievement test and sixth grade experimental class. 2) In the achievement test of inquiry process domain, there were some significant differences in that the sixth grade experimental class was higher than the third grade out-of classroom experience unit. It was indicated that the instructional use of the available materials around life had some effects on improving the students' inquiry ability 3) In achievement test of attitude domain, there were some significant differences. It was shown that the self-evaluation test of the sixth grade experimental class unit was higher than that of the third grade out-of classroom experience unit; Especially, the learning activities in the experimental class were more active, and the experimental practice ability was improved. It was presented that the instructional use of the available materials around life had some effects on the students' academic achievement in attitude domain. It was concluded from this study that the instructional use of the available materials around life was less effective on Knowledge understanding domain, but was effective on improving their scientific inquiry ability and interest on science education.

• Biomedical Science Letters
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• v.8 no.1
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• pp.1-5
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• 2002

Biotechnology "embraces everything from the production of recombinant proteins to the use of biological molecules as components of nanotechnology". Strategic-basic research in biotechnology is crucial to boosting world economy and creating jobs in the Life Sciences. Biotechnology will be the benefit to be drawn from biomedical life science research, which promises to be the new pillar of economy. Although the turnaround time for life science research products is painstakingly slow, the fruits of one such labour (Fig. 1), is being reaped fur worldwide biomedical applications.