• 천문학회보
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• 제46권1호
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• pp.44.2-45
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• 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.

• 한국지구과학회지
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• 제26권4호
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• pp.347-357
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• 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.

• 한국대기환경학회지
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• 제23권2호
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• pp.214-224
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• 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.

• 한국지구과학회지
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• 제36권5호
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• pp.476-483
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• 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.

• 상하수도학회지
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• 제33권6호
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• pp.429-436
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• 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.

• 한국과학교육학회지
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• 제27권6호
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• pp.465-476
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• 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.

• 대한가정학회지
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• 제28권4호
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• pp.177-189
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• 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%.

• 한국농공학회지
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• 제13권3호
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• pp.2372-2387
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• 1971

평균적기온(平均的氣溫) $3^{\circ}C$이상(以上)의 일수(日數)는 표20에서 보는 바와 같이, 최고(最高) 365일(日)로서 제주(濟州)이고, 다음이 부산(釜山)으로 334일(日) 그리고 해안지역(海岸地域)인 울산(蔚山), 포항(浦項), 목포(木浦), 여수(麗水) 및 울릉도(鬱陵島)가 306일(日)이고 기타(其他) 대구(大邱), 광주(光州) 이북(以北) 지역(地域)은 공(共)히 275일(日)로 최고(最高)와 최하(最下)는 90일(日)의 간격(間隔)이 있다. 2. 토공(土工)(전압(轉壓))작업(作業)에 영향(影響)을 미치는 동토기간(凍土期間)은 표-22에서 보는 바와 같이 1년(年) 365일(日)에서 표-26(1)항(項)의 일수(日數)를 감(減)하면 된다. 3. 월평균기온(月平均氣溫) $3^{\circ}C$이상(以上)의 일(日) 중(中)에서 1mm이상(以上)의 강우일수(降雨日數)는 토공(土工)(전압(轉壓))작업(作業)에 영향(影響)을 미치는 요소(要素)로서 표-18에서 보는 바와 같이 최고(最高)는 100(日)로서 제주(濟州)이고, 최하(最下) 60일(日)은 대구(大邱)이다. 타지역(他地域)은 거의 모두가 70일(日) 내외(內外)이고 다만 울릉도(鬱陵島)만이 90일(日)이다. 4. 년중(年中) 토공(土工)(전압(轉壓))가능일수(可能日數)(4)는 표-26에서 보는 바와 같이 월평균기온(月平均氣溫) $3^{\circ}C$이상(以上)의 일수(日數)(1)에서 이 기간중(期間中)의 1mm이상(以上)의 강우일수(降雨日數)에 1.27(토공지장계수(土工支障係數)을 승(乘)한 값(3)을 감(減)하면 [(1)-(3)=(4)] 된다. 5. 지역별(地域別) 년중(年中) 토공(土工)(전압(轉壓))가능일수(可能日數)는 최고(最高) 242일(日)로서 부산(釜山)이며 다음은 제주(濟州)로서 239일(日), 기타(其他)는 181일(日)${\sim}$218일(日) 양(郞) 200일(日) 내외(內外)로 되어 있다.

• 한국건설관리학회논문집
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• 제17권3호
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• pp.116-124
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• 2016

건설현장의 주요 작업인 토공사의 경우, 토공 건설장비를 운용하는 개별 작업자에 의해서 작업의 효율성이 좌우되기 때문에 개별 작업자의 숙련도가 전체적인 공사일정에 큰 영향을 미칠 수 있다. 건설현장에는 그 특성상 현장 내 설치된 구조물이나 장비 혹은 움직이는 작업자들이나 장비 등으로 인해 시야가 가려져서 발생하게 되는 비가시 영역이 필연적으로 존재한다. 이와 같은 작업 관련 시각정보의 부재는 작업자가 건설장비를 효율적으로 운용하는데 있어서 결정적인 저해요소가 된다. 증강현실(AR, Augmented Reality)은 현실세계에 가상물체를 중첩시켜 보여주는 컴퓨터 기술이다. 이 기술의 특성을 이용하면 토공사를 수행하는 과정에서의 시각정보 부재 문제를 해결할 수 있고 이를 통한 건설장비의 작업 효율성 향상이 가능하다. 본 연구의 목적은 이러한 토공사에서의 필요 시각정보를 도출하기 위한 작업-시각정보 맵을 제시하고 굴삭기의 작업들 중 AR기술을 적용하기에 적합한 것을 찾아내는 것이다. 연구의 대상이 되는 건설장비는 굴삭기로 한정하였다. 작업-시각정보 맵은 굴삭기 토공작업의 문제점과 그 문제점을 해결하는데 필요한 시각정보를 기반으로 하여 작성되었다. 이 맵으로부터 굴삭기의 작업 효율성을 향상시킬 수 있고, AR기술을 적용하기에도 적합한 4가지 필요 시각정보가 도출되었다. 연구결과를 바탕으로 하여 추후 건설장비 AR 네비게이터 시스템을 더욱 효과적으로 개발할 수 있을 것이라 기대한다.

• 한국지구과학회지
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• 제41권3호
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• pp.261-272
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• 2020

본 연구의 목적은 남한과 북한 지구과학 내용의 학습 시기와 학습량을 비교 분석하여 향후 통일을 대비한 남·북한 통합 교육과정 설계 및 우리나라 교육과정 개정 시에 참고할 수 있는 기초 자료를 제공하는 것이다. 연구 대상으로는 남한은 초등학교 5학년부터 중학교 3학년까지의 과학 교과서와 고등학교의 통합과학과 지구과학 I·II 교과서이며, 북한은 초급중학교의 자연과학 1·2와 조선지리 2, 고급중학교의 지리 1 교과서이다. TIMSS 2019의 8학년 지구과학 평가틀로 분석한 본 연구의 결과는 다음과 같다. 첫째, 남한은 반복 학습을 고려할 필요가 있다. 학습 이해에 효과적인 반복 학습이 적용된 내용은 8학년까지 1개에 그친다. 둘째, 남한은 학습 시기 조정을 고려할 필요가 있다. 북한과의 내용 시기 차이가 발생하고 TIMSS 기준 50%에 해당하는 내용의 학습 시기가 부합하지 않기 때문이다. 셋째, 남한과 북한은 학습하지 않은 TIMSS 내용을 반영할 필요가 있다. 이는 국제 사회에서 교육 경쟁력을 높이는 방안이 될 수 있다. 향후 남·북한의 지구과학 내용에 대한 접근 방법 비교 분석과 통합교육과정 설계를 위한 실질적 연구를 제안하였다.