• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.44.2-45
• /
• 2021

As implied by the zodiacal light and spacecraft impact measurements, the space between large bodies in our Solar System is filled with interplanetary dust particles (IDPs). IDPs give us deeper insight into the composition and evolution of the Solar System, as well as being a crucial reference for extrasolar research. IDPs can be interpreted as bearers of carbon and organic materials, and thus, their interaction with Earth can be considered as important factors for the birth of terrestrial life. One of the key routes of IDPs entering Earth is via meteoroid streams (Love and Brownlee 1993). The Geminid meteoroid stream is a notable example. Together with its source asteroid (3200) Phaethon, the Phaethon-Geminid stream complex (PGC) (Whipple 1983; Gustafson 1989) can potentially provide information on the properties and evolution of IDPs in near-Earth space. DESTINY+* is a JAXA/ISAS spacecraft planned to launch in 2024 to explore the physical and chemical features of near-Earth IDPs and uncover the dust ejection mechanism of active near-Earth asteroids, especially Phaethon (Arai et al. 2018). Previous studies on the dust ejection mechanism of Phaethon have various degrees of success in explaining the ejection of submillimeter particles and try to recreate the dust replenishment rate of the Geminid stream. However, none of them are satisfactory for explaining the observed Geminid stream, especially for larger particles of a millimeter and centimeter scales. Inspired by the discovery of rotational mass shedding in the Main Belt region (Jewitt et al., 2014), we investigate a dust ejection scenario by rotational instability on Phaethon. Using the N-body integrator MERCURY6 (Chambers 1999; modified by Jeong 2014), we performed a long-term integration of dust particles of various sizes ejected at ~1 m/s. Through this process, we discuss the implications Phaethon's rotation may have on its ejection, the formation and evolution of IDP by this mechanism, and contribute to the DESTINY+ mission.

• Journal of the Korean earth science society
• /
• v.26 no.4
• /
• pp.347-357
• /
• 2005

Since 1998, an elementary teacher education institute in Korea has hosted the center for the gifted education. The institute hired undergraduate students to escort and liaison each class of the gifted student participants with assisting classroom activities. These liaison teachers observed the gifted classroom activities and evaluated them by using a given checklist and filling out pre-made evaluation forms. Currently this system is being transferred from part-time jobs for students to earn allowance into well organized pre-service teacher program focusing on the gifted education. In other words, the purpose of system is being shifted from how liaison teachers facilitate the gifted program to how the system helps the liaison teachers to be quality teachers for the gifted who can understand what the gifted are and how to facilitate them. Analyzed were the self reports of the liaison teachers regarding their perceptions and beliefs of the gifted and their education program. It was found participant liaison teachers purposed to have more live experiences with getting along with students as well. Liaison teachers’ perceptions on establishing a gifted teacher professional education sequence were reported in this study. The potential scaffolding of the pre-service teacher education program model of the gifted education was provided as a consequence of this study.

• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.2
• /
• pp.214-224
• /
• 2007

A three-dimensional computational fluid dynamics (CFD) model with the renormalization group (RNG) $k-{\varepsilon}$ turbulence model is used to examine the effects of difference in building height on flow and pollutant dispersion in asymmetric street canyons. Three numerical experiments with different street canyons formed by two isolated buildings are performed. In the experiment with equal building height, a portal vortex is formed in the street canyon and a typical recirculation zone is formed behind the downwind building. In the experiment with the downwind building being higher than the upwind building, the ambient flow comes into the street canyon at the front of the downwind building and incoming flow diverges strongly in the street canyon. Hence, pollutants released therein are strongly dispersed through the lateral sides of the street canyon. In the experiment with the upwind building being higher than the downwind building, a large recirculation zone is formed behind the upwind building, which is disturbed by the downwind building. Pollutants are weakly dispersed from the street canyon and the residue concentration ratio is largest among the three experiments. This study shows that the difference in upwind and downwind building height significantly influences flow and pollutant dispersion in and around the street canyon.

• Journal of the Korean earth science society
• /
• v.36 no.5
• /
• pp.476-483
• /
• 2015

The high-order Laplacian-type filter, which is capable of providing isotropic and sharp cut-off filtering on the spherical domain, is essential in processing geophysical data. In this study, a spherical high-order filter was designed by combining the Fourier method with finite difference-method in the longitude and latitude, respectively. The regular grid system was employed in the filter, which has uniform angular spacing including the poles. The singularity at poles was eliminated by incorporating variable transforms and continuity-matching boundary conditions across poles. The high-order filter was assessed using the Rossby-Haurwitz wave, the observed geopotential, and observed wind field. The performance of the filter was found comparable to the filter based on the Galerkin procedure. The filter, employing the finite difference method, can be designed to give any target order of accuracy, which is an important advantage being unavailable in other methods. The computational complexity is represented with 2n-1 diagonal matrices solver with n being the target order of accuracy. Along with the availability of arbitrary target-order, it is also advantageous that the filter can adopt the reduced grid to increase computational efficiency.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.6
• /
• pp.429-436
• /
• 2019

Since the discovery of the first artificial synthetic plastic, bakelite, polymer materials have been recognized as one of the most innovative fields of research. The plastic debris that is being piled up on the earth (called abandoned plastic litters) is now being observed everywhere on Earth, becoming an increasingly serious environmental threat. The term 'microplastics', created in 2004, now refers to plastic particles that are smaller than 5 mm, including all nano-sized plastic particles. However, there is no legal regulation, and there is still a lack of comprehensive definitions that practically include microplastic size standards. In this study, we will refer to "microplastics" as the English name, and look at how to identify these microplastics and propose new definitions that focus on their size. This study is expected to contribute to the domestic consensus on scientific definitions of microplastics.

• Journal of The Korean Association For Science Education
• /
• v.27 no.6
• /
• pp.465-476
• /
• 2007

Whether and when naturalistic or supernaturalistic explanations of the origins of sun and earth, humans, life and species change with development was explored in a questionnaire and interviews with 32 first graders and 32 second graders, and in a questionnaire with 34 third graders, 32 sixth graders and 38 eighth graders. Participants were also asked about factors affecting their explanations in the questionnaires. Even the first and second graders could consistently provide supernaturalistic or naturalistic explanations on both the origins of sun and earth, and of humans. There was an age-related developmental shift from supernaturalistic to naturalistic explanation. As for origins of species, most of the first and second graders held the spontaneous generationist explanation, and after the third grade their views divided into evolutionist and creationist explanations. Students' explanations of species origins were established by the sixth grade through a transitional stage in the third grade. At the first and second grade levels, books and the children's own reasoning mainly influenced the views of origins, whereas parents and school were not perceived as being important. For the third graders and higher-grade levels, several factors, including parents and religion, were perceived as being important. These results show that explanations of origins start to develop earlier than or during the first grade, and are established by the sixth grade; moreover, the formation of these views is affected by several factors in addition to development.

• Journal of the Korean Home Economics Association
• /
• v.28 no.4
• /
• pp.177-189
• /
• 1990

The purpose of this study were to measure the body cathexis and the characteristics of middle-aged women groups segmented by their fashion orientation. Self-administered questionaire method was used. Seven demographic variables, 9 self-images, body cathexis were included as independent variables. Fashion orientation developed by Gutman and Mills was used. Data was collected from 369 Middle-aged women in Chonbuk Province. Frequencies, Percentages, means, standard deviation were caculated. ANOVA, cluster analysis, and discriminant analysis were used for data analysis. The results were as follows: 1. The body cathexis of the subjects were lower than capital city and increased according to age. 2. The self-image of the subjects were down-to-earth, modern, conventional, playing it safe, confident, stable, reserved and blending out into a crowd. The subjects with the self-image of being more sophisticated, confident, creative, stood out in a crowd, or complicated life style had higher body cathexis. 3. When the subjects were divided into segmentations according to their fashion orientation by cluster analysis, the best suitable number of groups was seven. The characteristics of seven groups were: *Fashion negatives showed low levels of fashion leadership and fashion interest, and medium level of importance of being well-dressed, and high level of antifashion attitudes. *Fashion neutrals showed medium levels of fashion leadership, fashion interest, and importnace of being-well dressed, and low level of antifashion attitudes. *Fashion uninvolveds showed low levels of fashion leadership, fashion interest, and antifashion attitudes. *Fashion followers showed high levels of fashion interest and importance of being well dressed, but low levels of fashion leadership and antifashion attitudes. *Fashion independents showed a littel bit high levels of fashion leadership, fashion interest, and importance fo being well-dressed, but low level of antifashion attitudes. *Fashion rejectors showed low levels of fashion leadership, fashion interest, and importance of being well-dressed, but high level of antifashion attitudes. 4. The seven groups segemented by their fashion orientation showed significant differences according to the educational levels, employment status, and total monthly income. Fashion leaders and fashion independents had higher educational level and monthly income, and involved more women with jobs. 5. Fashion leaders had self-image of being most sophisticated modern, diffenrent, creative, sociable, stood out in a crowd, and complicated life style. Fashion rejectors had self-image of being most down-to-earth, traditional, conventional, stable, reserved, blend into a crowd, and simplified life style. 6. The most effective variables among body cathexis, demographic variabls and self-images in discirminating fashion oreintation group differences were different-conventional, creativestable, and employment status. The discriminating power of above variables were high in very low in discriminating fashion negatives, fashion neutrals, and fashion independents, and the total discriminating power of these variables was 32.25%.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.13 no.3
• /
• pp.2372-2387
• /
• 1971

1. Being seen at the table (20), the number of days which monthy average air temperatures are three degrees of Celsius thermometer($3^{\circ}C$) or more, is the highest marks to be 365 days at Cheju, secondly, 334 days at Pusan, and, Ulsan, Pohang, Mokpo,Yosu and Ullung-Do which all are coastal region are all 306 days, besides, all north area of Taegu and Kwang ju have 275 days consquently, there are 90 days, differance between maximum and minimum. 2. Being seen at the table(22), freezing dates to be influenced upon earth works are obtained, if (1) item is subtracted from 365 days one year. 3. Being seen at the table(18), number of rainy days of which records are 1 millimeter and over to be influenced upon earth through works, days which monthly average air temperatures are $3^{\circ}$ or more, is the maximum to be 100 days at Cheju and its minimum is 60 days at Taegu. Every other region show 70 days or so. But Ullung-Do is 90 days. 4. Being seen at the table (26), the numbers of annual earth works possibility days(4) are obtained, if the values (3) which number of rainy days more than 1 millimeter during the same period are multiplied by 1.27(coefficient of hindrance to earth works) are subtracted from the number of days which monthly average air temperatures $3^{\circ}$ or more [(1)-(3)=(4)]. 5. The number of annual earth works possibility days by regional groups is the maximum to be 242 days at Pusan, and Cheju are 239 days. Other regions are from 218 days to 181 days, namely, they are about 200 days.

• Korean Journal of Construction Engineering and Management
• /
• v.17 no.3
• /
• pp.116-124
• /
• 2016

Work efficiency of earth work which is one of the main works occurring in construction site mainly depends on the performance of individual operators of earth work equipment. Consequently, the skill of individual operators of earth work equipment can significantly affect overall construction schedules. Many invisible areas inevitably exist in construction site because of the nature of construction site where occlusions occur from structures being built, installed or moving equipment, moving workers, etc. The lack of visual information regarding tasks critically impedes the effective performance of operators of earth work equipment. AR (Augmented Reality) is a computer technology that superimposes virtual objects onto the real world scene. This characteristic of AR may address the lack of visual informations in earth work process, thus helping to improve the work efficiency of operators of earth work equipment. The purpose of this study is to present a task-visual information map that identifies visual informations required in tasks of earth work and which of the tasks are suitable for AR technology. This study focuses on visual informations in tasks of earth work with excavators. The map was created based on the investigations on the problems of each task of earth work with excavators and visual informations required to address the problems. Through the map, four visual informations were found to be suitable for AR technology to improve the work efficiency of excavator operators. Based on the findings of this study, AR systems for excavators can be developed more effectively.

• Journal of the Korean earth science society
• /
• v.41 no.3
• /
• pp.261-272
• /
• 2020

The purpose of this study was to compare the earth science curriculums of South Korea and North Korea. Aspects such as the content of the curriculums and the timing of learning were analyzed, in order to provide basic data that can be used to design a revised and integrated Korean curriculum. The objects of this study were South Korean Science textbooks from grades 5-9, and the high school Unity of Science and Earth Science I and II textbooks. Additionally, from North Korea, the junior middle school Natural Science 1 and 2 textbooks and the senior middle school Chosun Geography 2 and Geography 1 textbooks were analyzed. The results of this study obtained through an analysis that used the Trends in International Mathematics and Science Study (TIMSS 2019) grade 8 earth science assessment framework were as follows. First, South Korea needs to adopt iterative learning. Repetitive learning, which is effective for understanding what is being learned, is applied to only 1 by 8th grade. Second, South Korea needs to adjust the time when certain content is learned. This is because there is a disparity between when content is learned in comparison to North Korea, and the timing of learning of about 50% of the TIMSS standards have not been followed. Third, it is necessary to reflect the content present within the TIMSS that have not been learned. This can be a way to increase the nations' educational competitiveness in the international community. This paper proposed a comparative analysis of South korean and North Korean approaches to the earth science curriculum and conducted practical research to facilitate the construction of an integrated curriculum.