• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2006년도 춘계학술대회 학술발표 논문집 제16권 제1호
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• pp.241-244
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• 2006

본 논문은 지구자계를 이용하여 3축 자계센서의 수직 성분자계를 보정하는 방법과 장치를 제안한다. 자계센서는 설치각도 및 이득오차에 의해 출력 특성이 변화한다. 따라서 자계센서를 사용하기에 앞서 보정이 필요하다. 지구에서 발생되는 지구자계를 이용하여 간편하게 센서의 설치각도 및 이득오차에 의한 영향을 보정하였으며 이를 위한 장치를 설계하였다. 제안한 방법은 실험을 통하여 실용성을 검증하였다.

• Journal of Magnetics
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• 제18권3호
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• pp.308-310
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• 2013

Translation induced by the field-gradient force is being observed for a single ferromagnetic iron grain and a ferrimagnetic grain of a ferrite sample ($CuFe_2O_4$). From measurements on the translation, precise saturated magnetization of $M_S$ is possible for a single grain. The method is based on the energy conservation rule assumed for the grain during its translation and the grain is translated through a diffuse area under microgravity conditions. The results of the two materials indicate that a field-induced translation of grain bearing spontaneous moment is generally determined by a field-induced potential $-mM_SH(x)$ where m denotes the mass of sample. According to the above translations, the detection of $M_S$ is not interfered by any signals from the sample holder. The $M_S$ measurement does not require m value. By observing translations resulting from fieldinduced volume forces, the magnetization of a single grain is measurable irrespective of its size; the principle is also applicable to measuring susceptibility of diamagnetic and paramagnetic materials.

• Geomechanics and Engineering
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• 제34권1호
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• pp.17-27
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• 2023

Taking a subway shield tunnel in a certain section of Zhengzhou Metro Line 5 as an example, the field tests of shield cutting cement-soil monopile composite foundation were carried out. The load and internal force of the tunnel lining under the action of composite foundation were tested on-site and the distribution characteristics and variation laws of earth pressure around the tunnel under the load holding state of the composite foundation were analyzed. Five different load combinations (i.e., overburden load theory + q₀, Terzaghi's theory + q₀, Bierbaumer's theory + q₀, Xie's theory + q₀, and the proposed method (the combination of compound weight method and Terzaghi's theory) + q₀) were used to calculate the internal force of the tunnel structure and the obtained results were compared with the measured internal force results. The action mode of earth pressure on the tunnel lining structure was evaluated. Research results show that the earth pressure obtained by the calculation method proposed in this paper was more consistent with the measured value and the deviation between the two was within 5%. The distribution of the calculated internal force of the tunnel structure was more in line with the distribution law of field test data and the deviation between the calculated and measured values was small. This effectively verified the rationality and applicability of the proposed calculation method. Research results provided references for the design and evaluation of shield tunnels under the action of composite foundations.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.411-418
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• 2001

The last 30 years have been significant worldwide growth in the use of EPS as a lightweight fill material. This paper analyzes the compressible inclusion function of EPS which can results in reduction of static earth pressure by accomodating the movement of retained soil. A series of model tests was conducted to evaluate the reduction of static earth pressure using EPS inclusion and determine the optimum stiffness of EPS, Also, field test was conducted to evaluate the reduction of static earth pressure using EPS inclusion. Based on field test it is found that the magnitude of static earth pressure was reduced about 20% compared with theoretical active earth pressure.

• 대한지구과학교육학회지
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• 제4권2호
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• pp.142-150
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• 2011

This study is aimed to offer the elementary school teacher's experience and awareness about science field trip and science museum field trip, by analyzing the survey of 867 students and 81 teachers in Seoul. Research shows 67.9% high figure of elementary school teacher's experience on science field trip. That experience is include 61.8% of science museum using experience. In case of elementary school teacher's pre-activity is only 53.1% and most of them was visiting Website. Post-activity is more than preceding activity(74.1%) but method is too simple like checking work sheets. 62.3% of elementary school students have been to science field trip and science museum that is higher than teachers'. 66.5% of students said science field trip is influence on science study in good ways but there are some difficulties like lack of pre-activity(33.0%) and unkind information about science museum(21.9%). For activation of science field trip, resources development for effective science field trip operating, program development for pre- and post-activity, school group science field trip program development which is linked science curriculum, complement and expand activity information of science field trip institution.

• Journal of Astronomy and Space Sciences
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• 제27권2호
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• pp.97-106
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• 2010

To prepare for a Korean lunar orbiter mission, a precise lunar orbit propagator; Yonsei precise lunar orbit propagator (YSPLOP) is developed. In the propagator, accelerations due to the Moon's non-spherical gravity, the point masses of the Earth, Moon, Sun, Mars, Jupiter and also, solar radiation pressures can be included. The developed propagator's performance is validated and propagation errors between YSPOLP and STK/Astrogator are found to have about maximum 4-m, in along-track direction during 30 days (Earth's time) of propagation. Also, it is found that the lifetime of a lunar polar orbiter is strongly affected by the different degrees and orders of the lunar gravity model, by a third body's gravitational attractions (especially the Earth), and by the different orbital inclinations. The reliable lifetime of circular lunar polar orbiter at about 100 km altitude is estimated to have about 160 days (Earth's time). However, to estimate the reasonable lifetime of circular lunar polar orbiter at about 100 km altitude, it is strongly recommended to consider at least $50\;{\times}\;50$ degrees and orders of the lunar gravity field. The results provided in this paper are expected to make further progress in the design fields of Korea's lunar orbiter missions.

• 한국지구과학회지
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• 제31권5호
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• pp.500-520
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• 2010

The purposes of this case study were (1) to explore one experienced teacher's views on Earth Systems Education and (2) to describe and document the characteristics of the Earth Systems Education (ESE) curriculum provided by an exemplary middle school science teacher, Dr. J. All the essential pieces of evidence were collected from observations, interviews with the experienced teacher and his eighth grade students, informal conversations, document analysis, and field notes. The $NUD^*IST$ for MS Windows was used for an initial data reduction process and to narrow down the focus of an analysis. All transcriptions and written documents were reviewed carefully and repeatedly to find rich evidence through inductive and content analysis. The findings revealed that ESE provided a conceptual focus and theme for organizing his school curriculum. The curriculum offered opportunities for students to learn relevant local topics and to connect the classroom learning to the real world. The curriculum also played an important role in developing students' value and appreciation of Earth systems and concern for the local environment. His instructional strategies were very compatible with recommendations from a constructivist theory. His major teaching methodology and strategies were hands-on learning, authentic activities-based learning, cooperative learning, project-based learning (e.g., mini-projects), and science field trips. With respect to his views about benefits and difficulties associated with ESE, the most important benefit was that the curriculum provided authentic-based, hands-on activities and made connections between students and everyday life experiences. In addition, he believed that it was not difficult to teach using ESE. However, the lack of time devoted to field trips and a lack of suitable resource materials were obstacles to the implementation of the curriculum. Implications for science education and future research are suggested.

• 한국자기공명학회논문지
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• 제23권1호
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• pp.12-19
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• 2019

A former study has shown that the spin-lattice relaxation time ($T_1$) in cancerous prostate tissue had enhanced contrast at an ultra-low magnetic field, $132{\mu}T$. To study the field dependence and the origin of the contrast we measured $T_1$ in pairs of ex-vivo prostate tissues at the Earth's magnetic field. A portable and coil-based nuclear magnetic resonance (NMR) system was adopted for $T_1$ measurements at $40{\mu}T$. The $T_1$ contrast, ${\delta}=1-T_1$ (more cancer)/$T_1$(less cancer), was calculated from each pair. Additionally, we performed pathological examinations such as Gleason's score, cell proliferation index, and micro-vessel density (MVD), to quantify correlations between the pathological parameters and $T_1$ of the cancerous prostate tissues.

• 전자공학회논문지A
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• 제33A권12호
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• pp.9-15
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• 1996

An electric field induced by a point dipole soruce within a conductor-backed lossy dielectric slab above the earth is calculated by anumerical method. the calcualtion is peformed on the plane which is parallel to the conductor plane and containing the point dipole soruce. Computed S$_{21}$ values of two parallel planar dipole antennas and two collinear planar dipole antennas are compared against each other, as well as the electic field magnitudes in those arrangements.

• Journal of Astronomy and Space Sciences
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• 제29권4호
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• pp.329-336
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• 2012

Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Bohyunsan Observatory to measure the Earth's magnetic field variations in South Korea. In 2007, we installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we use the H, D, Z components of fluxgate magnetometer data to investigate the characteristics of mid-latitude geomagnetic field variation. To remove the temporary changes in Earth's geomagnetic filed by space weather, we use the international quiet days' data only. In other words, we performed a superposed epoch analysis using five days per each month during 2008-2011. We find that daily variations of H, D, and Z shows similar tendency compared to previous results using all days. That is, H, D, Z all three components' quiet intervals terminate near the sunrise and shows maximum 2-3 hours after the culmination and the quiet interval start from near the sunset. Seasonal variations show similar dependences to the Sun. As it becomes hot season, the geomagnetic field variation's amplitude becomes large and the quiet interval becomes shortened. It is well-known that these variations are effects of Sq current system in the Earth's atmosphere. We confirm that the typical mid-latitude geomagnetic field variations due to the Sq current system by excluding all possible association with the space weather.