• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.299-304
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• 2011

A hydrogen fueled 2 stroke free-piston engine with reverse uni-flow scavenging have a advantageous structure for the backfire occurrence, but it can reduce thermal efficiency by the circuit-flow to go through a exhaust-port. In this research, varied boost pressure, SVOT and exhaust pressure are used in a 2stroke free-piston engine with hydrogen fueled for studying the possibility of increasing thermal efficiency of free-piston hydrogen engine. As a result, to increase thermal efficiency of free-piston are suitable to supply the mixture after port closed the exhaust rater than to use the scanvenging. And it was increased by the exhaust pressure, to achieve it must be used the lean-mixture at SVOT aBDC $34^{\circ}$.

• 한국수소및신에너지학회논문집
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• 제17권1호
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• pp.1-7
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• 2006

The free-piston hydrogen fueled engine is estimated as the next generation power system which can obtain high efficiency and low emission, simultaneously. In order to develop the free-piston hydrogen fueled engine, it is necessary to stable the combustion. The engine combustion, backfire and knock phenomenons were studied by using RICEM for researching combustion characteristics of free-piston engine. As the results, backfire occurrence was not observed in the free-piston engine under limited experimental condition. And knocking occurred in case of higher cylinder wall temperature.

• Archives of Reconstructive Microsurgery
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• 제15권2호
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• pp.51-57
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• 2006

Free flap having been used for reconstruction of skin and soft tissue defect in various areas in a body is spreading up its application for not only functional reconstruction but also aesthetic reconstruction. Authors met with good results minimizing the demerits of anastomosis using suture through microvascular anastomotic device, hereupon, we intend to report this. We worked with 27 cases that used microvascular anastomotic device for venous anastomoses among patients who were processed free flap in our hospital. Age ranged from 12 to 63 (average 43.2), and there were 12 females and 15 males. As a result of a follow-up by 3 months - 5years (average 11.3 months), there was no particular complication in the anastomosed vein except 1 cases among 27 cases that sutured their veins through microvascular anastomotic device. Use of microvascular anastomotic device at free flap shortened the time required for vascular anastomoses to reduce ischemic time of tissue, and minimized the damage of intima during anastomoses and made easy anastomoses possible even in case the difference of diameters of blood vessels being sutured is wide. As well, even for survival rate of flap, satisfactory results were obtained compared with using suture. Consequently, it is concluded that use of microvascular anastomotic device in free flap is a useful way that can substitute existing anastomosis using suture.

• 한국초등과학교육학회지:초등과학교육
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• 제39권2호
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• pp.243-254
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• 2020

This study analyzed the characteristics of "free inquiry" products for scientifically-gifted elementary school students. To do this, 5~6 graders (n=99) at a gifted science education institutes in Seoul were selected. The products (n=82) of "free inquiry" submitted by the students in 2018 and 2019 were analyzed according to their contents and method types. The analysis of the results showed that the free inquiry outputs of scientifically-gifted students tended to not include the scientific knowledge of the upper grades than the corresponding students. In the outputs, the scientific knowledge in different grades were often not linked. There were relatively many cases of convergence of knowledge in various science and/or non-science subjects and knowledge of 'physics', whereas knowledge of 'earth science' were the least. The outputs were more often aimed at "finding scientific facts" than "development and invention" and tended to target non-living things rather than living things. The scientifically-gifted students tended to conduct free inquiry using 'experimental-centered inquiry' by themselves rather than by group. They were also most likely to conduct experiments only once, and did not clearly write down the period of their inquiry. Educational implications of these findings are discussed.

• 한국세라믹학회지
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• 제54권2호
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• pp.86-95
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• 2017

Active search for lead-free piezoceramics over the last decade has harvested a considerable amount of achievements both in theory and in practice. Few would deny that those achievements are highly beneficial, but agree that this quest of developing the lead-free piezoceramics in replace for PZTs is successfully completed. Nevertheless, few would clearly state where this quest should be directed in our next move. A source of this uncertainty may originate from the fact that it is still not clear how good is good enough to beat PZTs. In this short review, we analyzed the existing literature data to clearly locate the current state of the art of lead-free piezoceramics in comparison to PZT-based piezoceramics. Four strategies of a potential importance were suggested and discussed to help researchers plan and design their future research on lead-free piezoceramics with a recently reported exemplary work.

• Child Health Nursing Research
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• 제6권3호
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• pp.354-361
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• 2000

The purpose of this study was to examine the stressors and coping styles between headache- suffering children and headache-free children. The subjects of this study consisted of 112 headache-suffering children and 203 headache- free children. They were 5th and 6th grade of elementary school around Taegu city. The periods of study was from June 1, to July 20, 2000. Data were analyzed by SAS computer programme The results of this study were as follows: 1. The score of stressor of headache-suffering children was higher than that of headache- free children significantly. The scores of school stressor and mess media stressor of headache-suffering children were higher than those of headache-free children significantly. 2. There was no significant difference even though the mean score of the coping style in headache-suffering children was higher than that of headache-free children. There were also no significant differences in both problem-oriented coping style and emotion- oriented coping style. 3. Logistic regression analysis(stepwise) revealed that the most powerful predictor was the variable stressor in school(standardized estimate=0.316, P<.001), followed by stressor in mass media(standardized estimate=0.224, P<.05).

• 한국초등과학교육학회지:초등과학교육
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• 제20권2호
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• pp.271-280
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• 2001

The purpose of this study is to investigate how free inquiry activities affects the scientific process skills and scientific attitudes of 5th and 6th of elementary school students. For this study, 265 elementary students from 5th and 6th grade in Seoul were selected. In comparison group 130 students were implemented and to the experimental group 135 students who did not the free inquiry activities were implemented. The result of this study is as follows: First, curiosity was the most affective factor that motivate free inquiry activities and made them select their topics. Most of the students invested for the inquiry activity in less than 3 weeks. They had some help in every stages. Students became interested in free inquiry activities because they learned new facts and enjoyed doing experiments and they wanted to continue for the same reasons. Second, free inquiry activities had little effect on the basic science process skills of the experimental group, compared to the control group at the significant difference of p=0.05. Third, free inquiry activities had considerable effect on the integrative inquiry process skills of the experimental group, compared to the control group at the significant difference of p=0.05. Fourth, the result of the post-test of the experimental group showed that free inquiry activities had no effect on scientific attitudes at the significant difference of p=0.05. In conclusion, free inquiry activities will be much more effective in developing integrative inquiry process skills than in developing basic scientific process skills and scientific attitudes.

• International Journal of Advanced Culture Technology
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• 제9권3호
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• pp.68-73
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• 2021

The 'Good School Uniform' development project was conducted in consultation with Gyeonggi-do and the Gyeonggi Provincial Office of Education. The aim is to find various ways to supply school uniforms reflecting the latest trends at low prices using high-quality textile materials produced in Gyeonggi-do. From 2015, when the 'Good School Uniform' development project started, to the present, various events and fairs are making great progress. However, there are several problems in actually wearing each middle and high school student. In order to satisfy the characteristics of each school and the satisfaction of parents and students together, it is necessary to not only conduct practical research such as closer customer satisfaction surveys, industry-academia-research networks, expert interviews, and surveys, but also several supplements such as consultations between practitioners. There are many domestic studies on the development of school uniform design, but the research on the revitalization plan according to the free school uniform support is very insufficient. Moreover, it is not easy to find recent studies on the development of 'Good School Uniforms'. This study intends to study how to build a system so that the Gyeonggi-do 'Good School Uniform' development project can be used as a role model. In addition, it is expected that this study will be used as basic data for building a nationwide system such as public brand development and collaboration with small domestic companies.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2007년도 추계학술발표대회 및
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• pp.97.2-97.2
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• 2007

• Advances in Traditional Medicine
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• 제10권4호
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• pp.304-309
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• 2010

Scutellaria pinnatifida A. Hamilt. (Lamiaceae) is an endemic Turkish herb. This plant is also endemic to Iran, and grows abundantly in other central and western Asian countries. Several species of the Scutellaria are known for their traditional uses in the treatment of hypertension, arteriosclerosis, inflammatory diseases, hepatitis, allergy, cancer and diarrhoea. Free-radical-scavenging property, antibacterial activity and brine shrimp toxicity of the n-hexane, dichloromethane (DCM) and methanol (MeOH) extracts of S. pinnatifida were assessed using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, the resazurin microtitre plate based assay, and the brine shrimp lethality assay, respectively. The DCM and MeOH extracts exhibited free-radical-scavenging property, with the $RC_{50}$ values of 0.362 and 0.127 mg/ml, respectively. Among the solid-phase extraction fractions of the MeOH extract, the 50% aqueous-MeOH fraction showed the highest level of free-radicalscavenging activity ($RC_{50}$ = 0.039 mg/ml). While the DCM extract showed low level of antibacterial activity against Bacillus subtilis and ampicillin-resistant Escherichia coli, the MeOH extract was active against B. cereus, B. subtilis, E. coli and ampicillin-resistant E. coli. However, the minimum inhibitory concentrations (MIC) of the MeOH extract against these bacterial strains were >10 mg/ml. None of the extracts showed any significant toxicity towards brine shrimps ($LD_{50}$ = > 1.00 mg/ml).