• 한국초등과학교육학회지:초등과학교육
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• 제33권2호
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• pp.286-305
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• 2014

We explored the possibilities of science field experience in Jongmyo Shrine in this study. To understand the educational value of self-leading science activities in Jongmyo Shrine, one of the World Heritage, we developed science program and applied it to the elementary students participating in a gifted education center. We collected and analyzed various data of opinionnaire survey before and after the program, field activity sheets, field observation, and individual- and group interview. The results showed the lack of students' spatial ability and proposed educational interests in science education. Also, a lot of students felt the difficulty in applying school science knowledge into the real life context. Students found the meaning of science learning through cooperative activities in the historically meaningful place. A proper use of smart device in science field experience was recommended. We found that activities with too much smart device might impede various scientific process skills.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.36-40
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• 2010

In recent society, the electricity is so essential for the human lives. Lots of modern people take many cultural benefits owing to the development of the power systems, the cell phone, the electrical appliances, and etc. However, the problems related to the electromagnetic field generate as the side effects. Examples are the fault in the electric machinery due to the electromagnetic coupling, the fault in the communication devices due to the electromagnetic field around the power line equipments, and the effect upon the human beings due to the electromagnetic field, and etc. In this paper, we induce the vector equation about the magnetic field based on Biot-Savart law. We calculate the magnetic field at the surface of the high speed train with this induced equation and the current in the high speed railroad catenary wire. Finally, we calculate the magnetic field in the high speed train considering the material property like the permeability, the conductivity, and so on.

• 기술사
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• 제42권6호
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• pp.28-30
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• 2009

There is a proverb in Korea "Don't chase after another." It can be a right proverb in sometimes. However, usually it doesn't fit in these various society, information knowledge society. Modern society requires convergence technology. IBS (Intelligent Building System) requires knowledge of architecture field, electric field, communication field, and computation field. ITS (Intelligent Transport Systems) which is constructing in many cities requires various knowledge as engineering works, electricity, computation, communication and transportation. In the case of u-City, it requires technology of many fields as architecture, electricity, communication, engineering works, transportation, and computation. Anyone who wants to participate in u-City should study and acquire knowledge in various field. Otherwise, it must be failed because of lack of communication like as the Tower of Babel. U-City is not a portion of one field. Therefore, engineers in many fields should cooperate with each other to make u-city as the best product in the world.

• 한국유기농업학회지
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• 제17권2호
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• pp.193-209
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• 2009

조사지역에서 출현한 저서성대형무척추동물은 총 3문 5강 13목 25과 32속 36종이었는데, 출현한 분류군별 양상을 보면 주로 정수역에서 출현하는 종들이 많았지만 일반적으로 유수역에서 출현하는 다슬기나 재첩, 각다귀 등도 출현하였다. 유기농법 지역에서 출현한 분류군은 3문 4강 12목 22과 27속 28종이었고, 관행농법을 하는 지역에서 출현한 분류군은 3문 5강 10목 19과 23속 25종으로 유기농법 지역에서 3종이 더 출현하였다. 출현 분류군별 특성은 크게 유의한 결과를 찾기 힘들었고, 관행농법지역에서 출현하지 않았으나 유기농법 지역에서만 출현한 종이 11종이었고, 관행농법 지역에서만 출현한 종이 8종이었다. 개체수는 두 지역간에 큰 차이가 있었는데, 관행농법 지역에서는 245개체가 출현한 반면 유기농법 지역에서 총 870개체가 출현하여 3.6배 이상 높게 나타났다. 종 다양도 지수는 1차 조사에서 관행농법 지역은 1.53-2.21의 범위와 유기농법 지역은 1.57-2.45의 범위를 나타내었다. 2차 조사에서는 각각 1.90-2.74와 0.71-2.61의 범위를 나타내어 우점도와 반대의 결과를 보여주었다.

• Journal of Astronomy and Space Sciences
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• 제37권2호
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• pp.131-142
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• 2020

As the laws of physics are expressed in a manner that makes their invariance under coordinate transformations manifest, they should be written in terms of tensors. Furthermore, tensors make manifest the characteristics and behaviors of electromagnetic fields through inhomogeneous, anisotropic, and compressible media. Electromagnetic fields are expressed completely in tensor form, F^αβ, which implies both electric field ${\overrightarrow{E}}$ and magnetic field ${\overrightarrow{B}}$ rather than separately in the vector fields. This study presents the Mathematica platform that generates and transforms a second-rank antisymmetric field-strength tensor F^αβ and whiskbroom pattern in Minkowski space. The platforms enhance the capabilities of students and researchers in tensor analysis and improves comprehension of the elegant features of complete structure in physics.

• Journal of Astronomy and Space Sciences
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• 제28권1호
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• pp.27-36
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• 2011

The present study examines the morning-afternoon asymmetry of the geosynchronous magnetic field strength on the dayside (magnetic local time [MLT] = 06:00~18:00) using observations by the Geostationary Operational Environmental Satellites (GOES) over a period of 9 years from February 1998 to January 2007. During geomagnetically quiet time (Kp < 3), we observed that a peak of the magnetic field strength is skewed toward the earlier local times (11:07~11:37 MLT) with respect to local noon and that the geosynchronous field strength is larger in the morning sector than in the afternoon sector. That is, there is the morning-afternoon asymmetry of the geosynchronous magnetic field strength. Using solar wind data, it is confirmed that the morning-afternoon asymmetry is not associated with the aberration effect due to the orbital motion of the Earth about the Sun. We found that the peak location of the magnetic field strength is shifted toward the earlier local times as the ratio of the magnetic field strength at MLT = 18 (B-dusk) to the magnetic field strength at MLT = 06 (B-dawn) is decreasing. It is also found that the dawn-dusk magnetic field median ratio, B-dusk/B-dawn, is decreasing as the solar wind dynamic pressure is increasing. The morning-afternoon asymmetry of the magnetic field strength appears in Tsyganenko geomagnetic field model (TS-04 model) when the partial ring current is included in TS-04 model. Unlike our observations, however, TS-04 model shows that the peak location of the magnetic field strength is shifted toward local noon as the solar wind dynamic pressure grows in magnitude. This may be due to that the symmetric magnetic field associated with the magnetopause current, strongly affected by the solar wind dynamic pressure, increases. However, the partial ring current is not affected as much as the magnetopause current by the solar wind dynamic pressure in TS-04 model. Thus, our observations suggest that the contribution of the partial ring current at geosynchronous orbit is much larger than that expected from TS-04 model as the solar wind dynamic pressure increases.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.443-450
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• 2000

In this study a numerical method for soil-pile interaction analysis buried in multi-layered half planes is presented in frequency domain using FE-BE coupling. The total soil-pile interaction system is divided into two parts so called far field and near field beam elements are used for modeling a pile and coupled with plain strain elements for soil modeling. Boundary element formulation using the multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered half-planes are performed and compared with experiment results. Through this developed method the dynamic response analysis of a pile buried in multi-layered half planes can be calculated effectively in frequency domain.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.189-189
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• 2009

This work was focused on the dielectrophoretic force of fullerenes dispersed in liquid crystal host medium, which are investigated in the homogeneously aligned liquid crystal (NLC) cells driven by external electric field. A fullerene of 10 wt% was doped into the LC medium and its electric field induced motion was controlled by both in-plane and vertical electric field. When the electric field was applied, the fullerene start to move in direction of applied electric field. The dark, grey and white states in the proposed device can be obtained by suitable combination of the polarity of applied electric field. The w and l are the width and distance between the electrodes. The reflectance at different l was measured and was found to be increased with increasing l. The dynamical motions of fullerene particles in LC medium suggest that fullerene can be designed for electronic-paper like displays.

• 정보학연구
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• 제12권2호
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• pp.49-55
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• 2009

Currently the Web, multiple files in the Client to upload to the server of the multi-upload method, files are stored in specific folders on the server, the file name field in DB(Database Field) stored in a way that the process has been widely utilized. Therefore, a minimum number of file upload as many file names in the Database and the Table should be created in the field, but also a variable number of files can be uploaded has no limits. In this paper we proposed the new method that files to be uploaded to the server, you can upload a limited number of files, nor due to upload files to reduce load on the database to improve the processing speed of a single field using a multi-method file uploads using PHP directly implemented

• 천문학회보
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• 제43권1호
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• pp.67.2-67.2
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• 2018

Magnetic fields play an important role in star-forming processes by regulating gravitational collapse. In filamentary structures of star-forming regions, magnetic fields are likely to be aligned with minor axes of filamentary molecular clouds because matter freely moves along magnetic field lines. Orion A region, one of the well-known high-mass star forming regions, has long filament structure. In order to study magnetic field directions with respect to the filamentary structure in Orion A, we have analyzed $850{\mu}m$ dust polarization observations obtained with the James Clerk Maxwell Telescope (JCMT). We found tight correlation of dust intensity gradients and magnetic field directions. It was estimated that 81% of magnetic field segments are aligned with density gradients within 40 degree. In conclusion, we confirmed most of magnetic field segments are perpendicular to the major axis of the filament in Orion A.