• Atmosphere
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• v.25 no.1
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• pp.169-177
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• 2015

Vertical distribution of particle mass concentrations was estimated from 8-year elastic-backscatter lidar and sky radiometer data, and from ground-level PM10 concentrations measured in Seoul. Lidar ratio and mass extinction efficiency were determined from aerosol optical depth (AOD) and ground-level PM10 concentrations, which were used as constraints to estimate particle mass concentration. The mean lidar ratio (with standard deviation) and mass extinction efficiency for the entire 8-year study period were $60.44{\pm}23.17$ sr and $3.69{\pm}3.00m^2g^{-1}$, respectively. The lidar ratio did not vary significantly with the ${\AA}ngstr{\ddot{o}}m$ exponent (less than ${\pm}10%$); however, the mass extinction efficiency decreases to $1.82{\pm}1.67m^2g^{-1}$ (51% less than the mean value) when the ${\AA}ngstr{\ddot{o}}m$ exponent is less than 0.5. This result implies that the particle mass concentration from lidar measurements can be underestimated for dust events. Seasonal variation of the particle mass concentration estimated from lidar measurements for the boundary layer, was quite different from ground-level PM10 measurements. This can be attributable to an inhomogeneous vertical distribution of aerosol in the boundary layer.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.210-218
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• 2018

Ethylenediaminetetraacetic acid (EDTA)-functionalized KIT-6 and KCC-1 mesoporous silicas were prepared via post-synthesis grafting and examined for their ability to promote the recovery of rare earth metal ions such as $Nd^{3+}$ from an aqueous medium. The obtained adsorption isotherms were fitted to the Langmuir model, which gave a maximum adsorption of $Nd^{3+}$ ions of 109.8 and 96.5 mg/g for KIT-6-EDTA and KCC-1-EDTA, respectively, at $25^{\circ}C$ and pH 6. The adsorption kinetic profile of KIT-6 was faster than KCC-1. KIT-6 was also proved to be more stable against desorption under acidic regeneration conditions.

• Geotechnical Engineering
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• v.13 no.5
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• pp.19-34
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• 1997

Classical earth pressure theories normally assume that ground condition remains uniform for considerable distance from the wall, and that the movement of the wall is enough to result in the development of an active pressure distribution. In the case of many low gravity walls in cut, constructed, for example, by using gabions or cribs, this is not commonly the case. In strong ground a steep temporary face will be excavated for reasons of economy, and a thin wedge of backfill will be placed behind the wall following its construetion. A designer then has the difficulty of selecting appropriate soil parameters and a reasonable method of calculating the earth pressure on the w리1. This paper starts by reviewing the existing solutions applicable to such geometry. A new silo and a wedge methods are developed for static and dynamic cases, and the results obtained from these are compared with two experimental results which more correctly mod el the geometry and strength of the wall, the fill, and the soil condition. Conclusions are drawn concerning both the magnitute and distribution of earth pressures to be supported by such walls.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.1
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• pp.69-79
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• 2021

The purpose of this study was to compare what meanings of earth science pre-service teachers and primary pre-service teachers about science books and reading through science disciplinary reading and how their thoughts on science education are reflected in the science disciplinary reading process. For the study, 24 third-year students majoring in earth science education and 25 second-year students majoring in primary education were selected as subjects for the study at a teacher training college located in the central part of Korea. As a result of the study, first, earth science pre-service teachers used disciplinary reading a lot to acquire knowledge of science content, but primary pre-service teachers used it for the purpose of using it in class, scientific interest, and curiosity solution. Second, earth science pre-service teachers and primary pre-service teachers showed differences in their thinking in using science related books for science education. While earth science pre-service teachers rarely described the use of science books in their classes, primary pre-service teachers actively described science classes. Third, from the perspective of science disciplinary reading, primary pre-service teachers were more actively emphasizing the meaning of disciplinary reading compared to earth science pre-service teachers. In light of the research results that the reading activity in science has a lot of effect, it is thought that a wide range of research on science disciplinary reading should be conducted as a teaching strategy in school field classes.

• Journal of the Korean Society of Earth Science Education
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• v.7 no.1
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• pp.11-23
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• 2014

The purpose of this study is to analyze the degree of argumentation structure development and factors of development of preservice teachers through SSI related argumentative writings. The study was conducted with 16 preservice teachers that students taking elementary science education theory class in K university located in Chungbuk. The testees wrote six SSI related argumentative writings (once a week), and we examined the degree of argumentation structure development and the change in the recognition of SSI of the preservice teachers by comparing the writings before and after the experiments. The experimental results showed that argumentation structure of the preservice teachers'writings improved and argument level (argument capability) of them also increased as the number of writing was increased. Factors that affect the argumentation structure improvement are mainly argumentation structure education, a number of writings, feedbacks, and subjects related to SSI. In this aspect, the argumentative writing on SSI has the effect of developing scientific sophistication and enhancing the decision-making power of students, and it has positive impacts in science education.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1864-1866
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• 1996

Grounding is the art of making an electrical connection to the earth. In order to protect man, electrical and/or electric equipments from the lightning strokes, all the energy of lightning strokes must be diverted via a safe path to earth. It is essential to the transient grounding resistance against lightning strokes. In this paper, measurements and analyses of grounding surge impedance have been investigated. For measurements of grounding surge impedance the pulse generator was designed and fabricated. The pulse generator has rise time of 22.4 ns and pulse duration of $8\;{\mu}s$. The transient grounding resistance has been measuring by injecting low power and step current between the earthing system under test and a remote reference earth and measuring the potential rise caused by this current. As a result, the transient grounding resistance against lightning surge in the short time domain is much higher than steady state grounding resistance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.163-171
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• 2006

The behaviors and design procedures of building excavation plane in innovative prestressed support (IPS) system are presented in this paper. Determination procedure for initial pretension in IPS wale subjected to design earth pressure is derived. The computer analysis model under uniform and non-uniform earth pressure is constructed using beam element for the IPS wale, tension-only element for cable, and compression-only element for soil. Axial forces and bending moments of IPS wale under initial pretension and design earth pressure are calculated. The combined stresses due to these axial force and bending moment are calculated and safety condition of building excavation plane is investigated.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.2
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• pp.166-174
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• 2012

This study is purposed to survey on astronomical observation experiences of elementary students and teachers. Survey samples are 182 elementary students and 51 elementary teachers, and 8 students and 2 teachers among them are interviewed. The results of this study show that most elementary students are not interested in observing constellations, planets, and moon. Also most elementary students and teachers are not taught to observe astronomical objects. Finally, regarding the difficulty of astronomical practice, teachers pointed out that lack of knowledge about astronomy.

• Journal of architectural history
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• v.14 no.4 s.44
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• pp.7-28
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• 2005

We are so used to the concept of the term 'space' that we do not question its conceptual validity. However, this paper argues that the notion of space prevailing all over the world, is not a universal concept that can be applicable to all architectures of the world, but is a particular concept that is generated from the Western way of thinking. This paper alms to identify the conceptual structure of the idea of space as it is originated in the tradition of the West, and, as an alternative view of space, tries to identify the nature of the view of space perceived in the tradition of the Eastern architecture. Comparison of the two views, that of the East and the West, and their meaning in the future of architecture, is another task to discuss in this paper. To be able to clarify the meaning of space in East Asian tradition, a set of new perspective of understanding of space was invited. They are ; 1. sky-earth(天地); insisting that the notion of space should be replaced within the context of sky, which is one half of sky-earth totality 2. energy of the air (空氣), space is not empty part inside of a building, but is a dynamic condition of air that is a part of the sky which always exist in form of energy 3. place(자리): instead of space, which, basically. is a man-made concept, idea of place is necessary, which include not only space but also earth Such concept of space which is different from the notion of space of the West, is meaningful not only to identify the idea of space in the East, but also to be able to contribute for more dynamic, varied, and balanced understanding of space.

• Journal of the Korean Society of Earth Science Education
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• v.10 no.2
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• pp.199-213
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• 2017

The purpose of this study was to find out what pre-service teachers' views of as a good science class in evaluating class demonstrations. The study was conducted on 32 students in the second year of college who are attending teacher training schools located in central region, Korea. 32 pre-service teachers demonstrated the class with a group of 2 students, and a total of 16 lessons were demonstrated. They also evaluated the class by participating in 15 lessons except ones own class. Therefore all the collected evaluation papers were 480 sheets. This study analyze this evaluation paper and find out the good science class that earth science pre-service teachers think. As a result, the pre-service teachers' views of good science class analyzed by 3 categories. The three categories were 'Highly Engaged Instruction', 'Well-structured class design', and 'Qualitatively superior class materials'. In other words, the pre-service teachers' views that well-structured class design and active interaction were the requirements of good science class. This study confirmed that pre-service teachers can draw images of good science class through experience of class demonstration and class evaluation.