• Journal of Powder Materials
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• 제25권3호
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• pp.213-219
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• 2018

We report a method for preparing rare earth oxides ($Re_xO_y$) from the recycling process for spent Ni-metal hydride (Ni-MH) batteries. This process first involves a leaching of spent Ni-MH powders with sulfuric acid at $90^{\circ}C$, resulting in rare earth precipitates (i.e., $NaRE(SO_4)_2{\cdot}H_2O$, RE = La, Ce, Nd), which are converted into rare earth oxides via two different approaches: i) simple heat treatment in air, and ii) metathesis reaction with NaOH at $70^{\circ}C$. Not only the morphological features but also the crystallographic structures of all products are systematically investigated using field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD); their thermal behaviors are also analyzed. In particular, XRD results show that some of the rare earth precipitates are converted into oxide form (such as $La_2O_3$, $Ce_2O_3$, and $Nd_2O_3$) with heat treatment at $1200^{\circ}C$; however, secondary peaks are also observed. On the other hand, rare earth oxides, RExOy can be successfully obtained after metathesis of rare earth precipitates, followed by heat treatment at $1000^{\circ}C$ in air, along with a change of crystallographic structures, i.e., $NaRE(SO_4)_2{\cdot}H_2O{\rightarrow}RE(OH)_3{\rightarrow}RE_xO_y$.

• Journal of the Korean Magnetics Society
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• 제22권5호
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• pp.188-193
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• 2012

Permanent magnet is one of the most important parts in modern industry and the rare earth elements play an essential role for operation of permanent magnet. As is well known, the rare earth elements are mostly produced in China and the world is now facing serious problems owing to supply and demand imbalances. Many attempts have been performed to replace these rare-earth based permanent magnets by rare-earth free magnets, but they have not been successful so far. Regarding this issue, we discuss about an exchange spring magnet as a potential rare earth free permanent magnet structure.

• Journal of the Korean earth science society
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• 제26권8호
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• pp.751-758
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• 2005

The purpose of this study was to develop an inquiry analysis framework based on the features of earth science inquiry methodology and to analyze inquiry activities in the 8th grade 'Earth History and Diastrophism' unit by using this framework. The framework classified earth science methods as logical inference, hermeneutic, and historical methods, each of which was subdivided in consideration of its subordinate methods and characteristics. The analysis revealed that the logical inference method reflected in the unit as the 'abductive method' (70%) was used more frequently than the 'inductive' (23%) and 'deductive' (22%) methods. The hermeneutic method was found in terms of the 'forestructures of understanding' (92%), 'circular reasoning' (9%). and 'historical nature of human understanding' (17%). The historical method also used as the 'constructing proper taxonomy' (53%), 'adhering to the modem principle of uniformitarianism' (47%), and 'relic interpretation' (41%) were identified with ratios more fester than those for the 'place substituting for time in stage theorizing' (3%) and 'evaluating independent lines of inquiry for convergence' (3%).

• Geophysics and Geophysical Exploration
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• 제14권1호
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• pp.18-24
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• 2011

A multi-channel seismic reflection (MCS) survey was conducted in 2009 to explore the deep crustal structure of the Pacific Plate south of Hokkaido. The survey line happened to traverse a 250-km-wide Warm Core Ring (WCR), a current eddy that had been generated by the Kuroshio Extension. We attempted to use these MCS data to delineate the WCR fine structure. The survey line consists of two profiles: one with a shot interval of 200m and the other with a shot interval of 50 m. Records from the denser shot point line show much higher background noise than the records from the sparser shot point line. We identified the origin of this noise as acoustic reverberations between the sea surface, seafloor and subsurface discontinuities, from previous shots. Results showed that a prestack migration technique could enhance the signal buried in this background noise efficiently, if the sound speed information acquired from concurrent temperature measurements is available. The WCR is acoustically an assemblage of concave reflectors dipping inward, with steeper slopes (${\sim}2^{\circ}$) on th ocean side and gentler slopes (${\sim}1^{\circ}$) on the coastal side. Within the WCR, we recognised a 30-km-wide lens-shaped structure with reflectors on the perimeter.

• Journal of the Korean earth science society
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• 제25권8호
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• pp.684-696
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• 2004

Using six preservice teachers as subjects, this was purpose to research about concepts in understanding carbon cycle, which of concepts were related to the conception of the system, and finally whether or not the systems thinking was sufficiently around carbon cycle. To achieve this study purpose , an instrument related to carbon cycle was developed and administered to the six teachers. The study found that a total of 42 conceptions within the system were concepts related to carbon cycle. The consisted of 15 conceptions in atmosphere, 11 in atmosphere 9 in hydrosphere, and 7 in lithosphere. In aspect of applying the system thinking, 4 subjects who couldn't compose the feedback loop in their causal map failed to apply this type of thinking. The other two who applied systems thinking had 2 and 1 feedback loop each, in their causal maps. But, one of the feedback loop from the subject who made two was based on unscientific reasoning. As a result, the subjects had lower understanding of concepts related to carbon cycle in lithosphere than in atmosphere, atmosphere, and hydrosphere. Futhermore, the subjects' application of the earth systems thinking on carbon was at a low standard.

• Journal of the Korean earth science society
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• 제27권4호
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• pp.486-502
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• 2006

Earth Science is the study of Earth, where diverse organisms live, and it mainly focuses on the healthy, wealthy, and comfortable environment for our descendants. UNESCO and IUGS recently established the International Working Group on Medical Geology (1996), IGCP 454 Medical Geology (2000-2004), and International Medical Geology Association (IMGA, 2006) with the primary concerns of increasing awareness of Medical Geology among scientists, medical specialists, and the general public. Medical Geology and IMGA have been very successful in informing(educating) about the relationship between geological factors and health problems in humans and animals in the world through numerous international meetings, seminars, workshops, symposiums, and publications. Since there is a close correlation between Earth Science and Medical/ Dental Sciences as shown in the Medical Geology and IMGA, Earth Science, as with other areas in science, (i.e., Biology, Chemistry and Physics) should be included in the Medical Education Eligibility Test (MEET) and Dental Education Eligibility Test (DEET) for the Medical and Dental Graduate School. In this brief note, services and activities of UNESCO IGCP 454 Medical Geology and IMGA are introduced, sothat the inclusion of Earth Science as a subject requirement in the MEET and DEET can be considered. Such outcome will balance the development of Science Education in Korea.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.421-426
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• 2001

The pneumatic classification and acidic leaching behaviors of phosphor sludge have been examined to establish the recycling system of rare earth components contained in waste fluorescent lamp. At first, separation characteristic of rare earth components and calcium phosphate in phosphor sludge was investigated by pneumatic classification. After pneumatic classification of phosphor sludge, rare earth components were leached in various acidic solutions and sodium hydroxide solution. For recovery of soluble component in leaching solution, rare earth components were separated as hydroxide and oxalate precipitations. The experimental results obtained are summarized as follows: (1) In classification process, rare earth components in phosphor sludge were concentrated to 29.3% from 13.3%, and its yield was 32.9%. (2) In leaching process, sulfuric acid solution was more effective one as a leaching solvent of rare earth component than other solutions. Y and Eu components in phosphor sludge were dissolved in sulfuric acid solution of 1.5 k㏖/㎥, and other rare earth components were rarely dissolved in leaching solution. Leaching degrees of Y and Eu were respectively 92% and 98% in the following optimum leaching conditions; sulfuric acid concentration is 1.5 k㏖/㎥ , leaching temperature 343 K, leaching time 3.6 ks and pulp concentration 30 kg/㎥. (3) Y and Eu components of phosphor sludge contained in waste fluorescent lamp were, effectively recovered by three processes of pneumatic classification, sulfuric acid leaching and oxalate precipitation methods. Their recovery was finally about 65 %, and its purity was 98.2%.

• Journal of the Korean earth science society
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• 제21권1호
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• pp.1-12
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• 2000

The earth science curriculum and textbooks of the secondary school in South Korea and North Korea were analysed comparatively with the modified TIMSS curriculum frameworks. In the secondary school of North Korea, earth science is not provided with separate subject, but partly taught in geography. Geography is taught by two hour per week in the first to fifth grade of secondary school. Especially the first and the fifth grade geography are deeply related to earth science. The major aim of earth science education in South Korea is to develop creative problem solver having with interest and curiosity in searching natural phenomena and with basic science concepts and inquiry process skills. But on the other hand the aim of geography education of North Korea is to cultivate communist revolutionists who are faithful to IL-Sung Kim and Jung-IL Kim. In both Koreas the category of 'earth feature' and 'earth process' are dealt a lot, but 'earth in the universe' is rarely taught in North Korea, which suggests that separate subject of astronomy is instructed in the North. Generally the scope and sequence of earth science of North Korea comes under those of middle school of South Korea. Especially discrepancy in level of meteorology and astronomy area between North and South Korea is great.

• Journal of the Korean Society of Earth Science Education
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• 제16권1호
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• pp.1-12
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• 2023

The purpose of this study is to investigate earth science pre-service teachers' perceptions and educational utilization of geoparks. It is intended to provide implications of geopark education in the current curriculum and effective geopark education. Education using geoparks has the effect of helping students cultivate inquiry and learning skills, enhancing students' participation in classes. To provide education with these results, it is necessary to deliver meanings of the geopark education to of earth science pre-service teachers who will educate future generations. However, despite the advantages and needs of geopark education, earth science pre-service teachers lack an understanding of geoparks. In this study, 56 pre-service teachers enrolled in earth science education at a university in Gyeongsangbuk-do were investigated for: their perception levels of geoparks, experience, necessity, and learning method of geopark education. As a result, earth science pre-service teachers were well aware of the geoparks, but they lacked knowledge of domestic and global geoparks, confirming the need for geopark education. Currently, the degree of geopark education in the secondary curriculum is insufficient, and earth science pre-service teachers feel the need for it. However, since the understanding of geopark is lacking, support for geopark education is needed. Earth science pre-service teachers being positive about the need for geopark education, it is expected that geopark education will be active in the field of earth science, social, and comparison education when they become teachers in the future.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1324-1329
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• 2009

Needs for underground space development and utilization have been increasing in urban area. The conventional strutting method in excavation is effective to restrain the ground movements and displacements of earth structures but inefficient for workers because of small working space. The conventional earth reinforcement methods such as earth-anchor and soil-nailing also have limitation to apply in urban area due to threats to stability of adjacent buildings around excavation boundaries. Recently, many types of earth retaining structures are being developed to overcome disadvantages of conventional excavation methods in urban area. In this study, a series of numerical analyses were performed with MIDAS GTS, geotechnical analysis program and MIDAS Civil, structural analysis design program to evaluate behavior and stability of the new type of non-supporting earth retaining structure, called Temporary Tower System (TTS), consisting of tower truss structures with much economical and spatial advantage.