• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.140-145
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• 2018

This paper deals with the dynamical analysis of a two-point mooring vessel under surge excitations. The characteristics of nonlinear behaviors are investigated completely including bifurcation and limit cycle according to particular input parameter changes. The strong nonlinearity of the mooring system is mainly caused by linear and cubic terms of restoring force. The numerical simulation is performed based on the fourth order Runge-Kutta algorithm. The bifurcation diagram and several instability phenomena are observed clearly by varying amplitudes as well as frequencies of surge excitations. Stable periodic solutions, called the periodic windows, can be obtained in succession between chaotic clouds of dots in case of frequency ${\omega}=0.4rad/s$. In addition, the chaotic region is unexpectedly increased when external forcing amplitude exceeds 1.0 with the angular frequency of ${\omega}=0.7rad/s$. Compared to the cases for ${\omega}=0.4$, 0.7rad/s, the region of chaotic behavior becomes more fragile than in the case of ${\omega}=1.0rad/s$. Finally, various types of steady states including sub-harmonic motion, limit cycle, and symmetry breaking phenomenon are observed in the two-point mooring system at each parameter value.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.140-140
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• 2016

유기전계발광소자 (Organic Light Emitting Diode : OLED)는 보조광원이 필요 없고 천연색 표현이 가능하며, 낮은 소비 전력 및 저전압 구동 등의 장점으로 이상적인 디스플레이 구현이 가능하여 차세대 디스플레이로써 많은 이목을 끌고 있으나 제한된 수명과 안정성의 문제점을 안고 있다. 따라서 OLED의 열화 원인을 분석하고 수명을 연장하기 위한 체계적인 방법과 기술 개발이 중요하다. Impedance Spectroscopy는 이온, 반도체, 절연체 등의 벌크 또는 계면 영역의 전하 이동을 조사하는데 사용될 수 있어, OLED에서도 Impedance Spectroscopy를 이용하여 전하수송과 전자주입 메커니즘 등 폭넓은 전기적 정보를 얻을 수 있다. 본 연구에서는 Impedance Spectroscopy를 이용하여 경과시간에 따른 OLED의 임피던스 특성을 측정하여 열화 메커니즘을 분석하였다. 본 연구에서 OLED는 ITO / 2-TNATA (4,4,4-tris2-naphthylphenyl-aminotriphenylamine) / NPB (N,N'-bis-(1-naphyl)-N, N'-diphenyl-1,1'- biphenyl-4,4'-diamine) / Alq3 (tris(quinolin-8-olato) aluminum) / Liq / Al으로 구성된 녹색 형광 OLED를 제작하였다. OLED의 전계 발광 특성을 측정하기 위한 전원 인가장치로 Keithley 2400을 사용하여 전압과 전류를 인가하였고, 소자에서 발광된 휘도 및 발광 스펙트럼은 Photo Research사의 PR-650 Spectrascan을 사용하여 암실 환경에서 측정하였다. 임피던스 스펙트럼은 컴퓨터 제어 프로그래밍이 가능한 KEYSIGHT사의 E4990A를 사용하여 측정하였다. 임피던스 측정 전압은 0 V부터 2 V 간격으로 8 V까지, 주파수는 20 Hz에서 2 kHz의 범위로 설정하여 측정하였다. I-V-L과 임피던스 특성은 24 시간의 간격을 두고 실온에서 측정하였다. 그림은 경과시간에 따른 녹색 형광 OLED의 인가전압 2 V, 6 V의 Cole-Cole plot을 나타낸 것이다. 문턱전압 미만인 인가전압 2 V에서는 소자를 통하여 전류가 흐르지 않아 큰 반원 형태를 나타내었고, 시간이 경과함에 따라 소자 제작 직후엔 실수 임피던스의 최댓값이 $8982.6{\Omega}$에서 480 시간 경과 후엔 $9840{\Omega}$으로 약간 증가하였다. 문턱전압 이상인 인가전압 6 V에서는 소자 제작 직후 실수 임피던스의 최댓값이 $108.2{\Omega}$으로 작은 반원 형태를 나타내나 시간이 경과함에 따라 방사형으로 증가하는 것을 확인 할 수 있었고, 672 시간 경과 후엔 실수 임피던스의 최댓값이 $9126.9{\Omega}$으로 문턱 전압 미만 일 때와 유사한 결과를 나타내었다. 이러한 임피던스의 증가 현상은 시간이 경과함에 따라 OLED의 열화에 의한 것으로 판단된다.

• Journal of agricultural medicine and community health
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• v.36 no.3
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• pp.167-178
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• 2011

Purpose: This study was done to identify the effects of a health diary program on fall related outcomes the low-income elderly women. Methods: The study was carried out with a nonequivalent control group with pretest-posttest design. The study was composed of two groups, each made up of 24 subjects: experimental group and control group. The subjects were low-income women aged over 65 years with osteoarthritis and both the experimental and control groups were made up of subjects with the same age profiles. The independent variable was the health diary program, and the dependent variables were fall related outcomes (fear of falling, fall-efficacy, knowledge of fall) difficulty of performing activity, and mood state. The health diary program was performed for 50 minutes each session and twice a week for 8 weeks. Data were collected before the health diary program 10 weeks after the beginning of the program. Results: The experimental group showed significant differences in knowledge of fall, fear of falling, and mood state compared to the control group. However there was no significant differences in difficulty of performing activity and fall efficacy. Conclusion: The results of this study may be used as part of an education to prevent falls for low-income elderly women with osteoarthritis.

• 대한공업교육학회지
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• v.44 no.2
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• pp.123-141
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• 2019

The purpose of this study is to provide basic data that can be used for the development of technology textbooks of Nigeria-Korea Model School by analyzing external and internal aspects of Illustration in Nigerian primary school technology textbooks, and 10 textbooks used in Nigeria were analyzed. Based on the results of the study, the conclusions are as follows. First, the form of the visual data should be diversified into a picture, a cartoon, a diagram, and a diagram from the photograph center, and provide various information closely related to the contents of the technology. Second, it is necessary to increase the size of illustration so as to induce learners to be motivated, and to enhance the effect of editing. Third, currently, partial enlargement data is rarely used, but visual material should be partially enlarged in order to express a detail part of product. Fourth, diversity of editing should be done by using circular or background omission rather than using only rectangle uniformly in visual material. Fifth, in terms of gender equality, it is necessary to deviate from male-centric visual materials and edit them with consideration for women. Sixth, in order to provide learner-centered textbooks, the role of visual materials should be extended to 'inducement of motivation', 'activity guidance', and 'activity result' in addition to 'providing data'. Finally, in terms of the function of visuals, the quality of textbooks should be upgraded by utilizing auxiliary and decorative functions in addition to essential functions.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.315-324
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• 2018

For Korean learners, writing is a harder part than any other areas in Korean languages. But in the future, the ability to organize and write systematically is essential for future koran languages learners to take classes, do assignments and presentations at school, and then adapt to job situations. Therefore, there is a need to devise a direction for this. In general, writing characteristics are viewed in many ways, including writing productivity, writing complexity, and writing errors. Accordingly, the study provided drawings and A4 paper for Vietnamese Korean learners, Chinese Korean learners, and Korean university students, before writing freely. Based on the their writing results, we looked at syntax factors (total C-units, total number of words), syntax complexity (number of words per C-unit and clause density), and writing errors (postposition, spell errors, and connective suffix, space errors) According to the study, Vietnamese and Chinese Korean language learners showed significantly lower syntax productivity and complexity than Korean university students, and showed more writing errors than Korean students in postposition and clause density. Based on the results of the study, we discussed writing guidelines for Korean languages learners. However, this study did not validate the differences in writing characteristics according to the Korean language level and length of residences for the study subjects. Therefore, it is necessary to consider this in future research.

• Journal of the Korean Society of Earth Science Education
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• v.13 no.3
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• pp.211-225
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• 2020

The purpose of this study was to investigate and analyze pre-service teachers' eye-movement in science textbooks in the learning process, whether they perceived "arrow" presented in textbooks, and changes in eye-movement by arrows. For the study, an eye-tracker, a eye-movement tracking device, was used, and 10 pre-service teachers attending a teacher training college were selected and conducted. The science textbook unit used in the research was the "Weather and Our Life" unit, one of the areas of earth science. As a result of the study, first, it was investigated that pre-service teachers devote more time to texts rather than illustrations in the learning process of science textbooks. Second, it was analyzed that pre-service teachers did not pay attention to the "arrow" presented in science textbooks. Third, it was confirmed that in order for "affordance of the eye-movement by arrow" to occur, sufficient concentration on "arrow" should be made. These findings suggest the importance of the learner's visual attention to learning elements in science textbooks such as "arrow". In addition, it suggests the importance of developing a textbook editing design that can induce visual attention to learning elements in textbooks through eye-movement research data for effective learning.

• Journal of Korean Home Economics Education Association
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• v.33 no.2
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• pp.115-133
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• 2021

The purpose of this study is to develop a teaching-learning plans for middle school Home Economics that practices clothing life in response to climate change. Four steps of analysis, design, development, and evaluation were used for the research. 'Phenomenon and cause, impact (environmental, economic and social) and response (relaxation and adaptation)' were selected as educational content elements for climate change through reviewing the literature related to climate change. Six types of middle school Technology and Home Economics textbooks under the 2015 revised curriculum were analyzed using the selected content elements for climate change as the basis for analysis according to the data type(reading data, picture data, activity data) and clothing use cycle (production, purchase, use, and disposal). Based on the content elements of climate change in the clothing life area extracted through textbook analysis, a total of 12 teaching-learning plans in response to climate change were developed by utilizing various teaching and learning methods, data and media. The teaching-learning plans were designed based on an integrated understanding of the phenomena, causes, effects, and responses of climate change for the students to realize the seriousness of climate change and to exercise positive influence on families and society.

• Journal of The Korean Association For Science Education
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• v.43 no.2
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• pp.73-86
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• 2023

This study compared the characteristics of scientific emoticons made by general and science-gifted elementary students. To do this, fifth graders (n=53) at a general elementary school in Gyeonggi province and fifth graders (n=35) at a gifted science education institute in Seoul were selected. Scientific emoticons written by the students were compared according to the number and types. Analysis of the results reveal that the science-gifted students made more scientific emoticons than the general students for thirty minutes. In the comparison of the types of scientific emoticons, there were some similarities and significant differences between general students and science-gifted students. Overall, however, it was found that science-gifted students made more various types of scientific emoticons than general students in 'form' aspects (e.g., generative form of text, descriptive form of text, and expressive form of image) and 'information' aspects (e.g., emotion, construction level, excess of curriculum level, scientific disciplines, and use of scientific knowledge) of the texts and the images in the scientific emoticons. The scientific emoticons made by general and science-gifted elementary students included very few misconceptions. Educational implications of these findings are discussed.

• Communications of Mathematical Education
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• v.37 no.3
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• pp.329-348
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• 2023

This study is necessary for the stable settlement of the 2022 revised mathematics curriculum 'data and possibility' area. This study was conducted centering on literature analysis. The purpose of this study is to realize statistics education in line with the 2022 revised mathematics curriculum. This purpose was achieved by examining the statistics learning contents of the 2022 revised curriculum, analyzing Chinese mathematics curriculum, and analyzing Chinese mathematics textbooks. In this study, the following studies were conducted. First, five elements were extracted through the analysis of the 'statistics and probability' area of the Chinese mathematics curriculum. The extracted elements are the 4th grade goals, synthesis and practice content areas, achievement standards for statistics and probability (6), (9), and (11). Second, examples presented in Chinese mathematics textbooks and Chinese curriculum appendices related to the extracted elements were analyzed. Regarding the 4th grade goal, the statistical problem-solving process of the 7th grade 2nd semester mathematics textbook was analyzed. Regarding the synthesis and practice content area, the data analysis unit of the 8th grade 2nd semester mathematics textbook was analyzed. In relation to the achievement standard (6), Example 85 of the curriculum appendix was analyzed, in relation to the achievement standard (9), Example 86 was analyzed, and in relation to the achievement standard (11), Example 87 was analyzed. Third, based on the analysis results, implications for the development of new curriculum and 'textbook development, teaching and learning methods' according to the 2022 revised middle school mathematics curriculum were derived. Through the results of this study, we expect the successful realization of the 2022 revised middle school mathematics and curriculum statistics education.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.133-139
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• 2024

The purpose of this study was to investigate the effects of robot play linked to environmental picture books on the Environmentally Friendly attitudes of 5-year-old children. For this purpose, 24 5-year-old children from Seoul Y Kindergarten and 20 5-year-old children from E Kindergarten were selected as comparison subjects. In order to examine the differences between the groups, the experimental group performed 'Robot Play Linked to Environmental Picture Books' and the comparative group performed 'Free Play After Appreciating Environmental Picture Books'. The collected data were analyzed through independent sample t-test, which compares the average between the two groups using SPSS 29.0 statistical program. As a result of the study, there was a significant difference in all sub-areas of children's environment-friendly attitude(nature-friendly attitude, environmental preservation attitude), and these findings are meaningful as a basis for the direction of new environmental education of play-centered early childhood environmental education based on the value of new play media support called robot.