• Progress in Superconductivity and Cryogenics
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• v.17 no.1
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• pp.44-47
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• 2015

High voltage superconducting apparatuses have been developed presently around the world under AC and DC sources. In order to improve electrical reliability of superconducting apparatuses with AC and DC networks, a study on the DC as well as the AC electrical breakdown characteristics of cryogenic insulations should be conducted for developing a high voltage superconducting apparatus. Recently, a sub-cooled liquid nitrogen cooling system is known to be promising method for developing a high voltage superconducting apparatus. A sub-cooled liquid nitrogen cooling system uses gaseous nitrogen to control the pressure and enhance the dielectric characteristics. However, the dielectric characteristics of gaseous nitrogen are not enough to satisfy the grade of insulation for a high voltage superconducting apparatus. In this case, the application of solid insulating barriers is regarded as an effective method to reinforce the dielectric characteristics of a high voltage superconducting apparatus. In this paper, it is dealt with a barrier effect on the DC and AC dielectric characteristics of gaseous nitrogen with respect to the position and number of solid insulating barriers. As results, the DC and AC electrical breakdown characteristics by various barrier effects is verified.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.25 no.4
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• pp.129-146
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• 2014

This study aims to present the effects that a bibliotherapy program based on picture books and paper craft art activities had on middle school students' stress recognition and the changes in their reactions. To this end, we adopted an experimental research design model with pre/post-test measurements of stress recognition and reactions using first grade middle school students with emotional difficulties. The results show that a bibliotherapy program based on picture books and paper craft art activities does have significant effects on the stress recognition and reactions of middle school students. The 5 of 5 sub-domains of the stress recognition had significant difference. The sub-domains are: family environment, friends, study, teacher/school. The 6 of 7 sub-domains of the stress reactions except fatigue had significant difference. The sub-domains are: tention, frustration, anger, depression, somatization, aggression.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.359-363
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• 2013

Silicon carbide and its composites are being considered as a nuclear fuel cladding material for LWR nuclear reactors because they have a low neutron absorption cross section, low hydrogen production under accident conditions, and high strength at high temperatures. The SiC composite cladding tube considered in this study consists of three layers, monolith CVD SiC - $SiC_f$/SiC composite -monolith CVD SiC. The volume fraction of SiC fiber and surface roughness of the composite layer affect mechanical and corrosion properties of the cladding tube. In this study, various types of SiC fiber preforms with tubular shapes were fabricated by a filament winding method using two types of Tyranno SA3 grade SiC fibers with 800 filaments/yarn and 1600 filaments/yarn. After chemical vapor infiltration of the SiC matrix, the surface roughness and fiber volume fraction were measured. As filament counts were changed from 800 to 1600, the surface roughness increased but the fiber volume fraction decreased. The $SiC_f$/SiC composite with a bamboo-like winding pattern has a smaller surface roughness and a higher fiber volume fraction than that with a zigzag winding pattern.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.31 no.1
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• pp.13-18
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• 2020

Background and Objective The purpose of this study is to report the effect of voice therapy using the voice reinforcement method (VRM) in patients with vocal nodules. It is one of the holistic voice therapy methods for improving vocal mechanisms. VRM includes not only direct and indirect voice therapy, but also trial therapy and self-practice. Composed of four stages: vocal hygiene education, relaxation, reinforcement, and generalization. Materials and Methods The subjects were 13 patients who were diagnosed with vocal nodules. Acoustic analysis, auditory perceptual assessment, K-VHI-10 and nodules size were compared before and after voice therapy. Voice therapy was conducted by speech-language pathologist and the mean number was 4.2. Results In acoustic analysis, Jitter, vF₀, vAm, Shimmer, NHR, and VTI were significantly decreased. F₀ was increased after voice therapy for women. 'Grade', 'Rough,' and 'Breathy' were significantly decreased in the GRBAS scale after voice therapy. In addition, K-VHI-10 and nodules size were significantly decreased. Conclusion VRM seems to be an effective voice therapy method in vocal nodules treatment. In VRM, especially, trial therapy is given motivation for vocal nodules treatments and self-practice has a continuous therapeutic effect in everyday life. VRM can be also applied to the voice therapy for other hyper-functional dysphonia.

• Journal of the Korean Geotechnical Society
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• v.39 no.8
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• pp.7-16
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• 2023

This study aimed to evaluate the sulfate removal capacity of the enzyme-induced carbonate precipitation (EICP) technique through the chemical precipitation of sulfate with calcium ions. The optimal EICP recipe was obtained to retain the excess calcium cations in the solution for the generation of a sufficient amount of calcium carbonate (CaCO₃) mineral. The effect of gypsum precipitation on the EICP-treated sand specimen was investigated by measuring the shear wave velocity and by visual inspection via scanning electron microscopy. The EICP solution using soybean crude urease, as an alternative to laboratory-grade purified urease, exhibited a lower sulfate removal efficiency at a similar CaCO₃ production rate compared with the optimal EICP recipe because of soybean impurities.

• Korean Journal of Plant Taxonomy
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• v.43 no.2
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• pp.146-160
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• 2013

The flora of vascular plants in the Mt. Cheonhwang, located at Miryang-si, Gyeongsangnam-do Province, was surveyed 16 times from March, 2009 to September, 2011. The result of this survey revealed 442 taxa in total, comprising 90 families, 252 genera, 387 species, 3 subspecies, 43 varieties, and 9 forms. Among the flora of this area, 14 taxa were plants endemic to Korea and 11 taxa were rare and endangered plants of Korea. The floristic regional indicator plants found in this area were 59 taxa: 2 taxa of grade V, 5 taxa of grade IV, 15 taxa of grade III, 16 taxa of grade II and 21 taxa of grade I. Alien plants in Korea numbered 21 taxa. In addition, 442 taxa were categorized by usage into 8 groups, as follows: 163 edible, 6 fiber, 125 medical, 76 ornamental, 163 pasturing, 4 industrial, 9 dyeing and 21 timber plants.

• Journal of Korean Elementary Science Education
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• v.19 no.1
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• pp.131-143
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• 2000

The unit of a buoyant force included in the 7th national science curriculum for 6th grade students. On the contrary, it seldom that students' conception about buoyant phenomena is studied, even though there has been many studies of students' conceptions of basic science contents. The purpose of this study was to survey the elementary school students' conceptions of a buoyant force, to analyze their cognitive levels, and to explore the relationships between them. Sixth grade students (total numbers is 192) were selected .from 5 .lasses in two elementary schools in a local city of Kyungsangdo. They were asked to respond two kinds of test, which are the Logical Thinking Ability (GALT) to investigate students' cognitive levels and the Buoyant Force Questionnaire (BFQ). We developed BFQ test, based on the 7th national science curriculum for 6th grade and the previous researches of a buoyant force. We, qualitatively, analysed students' frequency of responses about a buoyant force and their types of explanation, and, quantitatively, analysed the relationships between cognitive levels and conceptions of a buoyant force with SPSS/ PC 7.0 programmes. The results of cognitive level showed that half of 6th grade students were in the concrete operational stage, 43.2% in the transitional stage, 6.8% in the formal stage. However, their sub-logical thinking abilities in a combinational, conservational, controlling variables, proportional, probability and correlational logic were very fluctuated from 91% to 8%. The results that only 4.8% of elementary students had correct conceptions of a buoyant force suggest that 6th grade students had great difficulties in understanding of that concept. Their difficulties would originated from the frequent common-sense explanations of a buoyant phenomena in terms of the weight or the unique properties or the contact area of an object or with/without air. Furthermore students' explanations, frequently, changed with context of problems of a buoyant force. Scheffe test of quantitative results that elementary students in the concrete level had 50.6% of concept formation in a buoyant force, the transitional level 54.5%, and in the formal operational level 62.8% showed significant differences of conceptions of a buoyant force with cognitive levels. Therefore the concrete operational elementary students had more difficulties of understanding of a buoyant force than the transitional and formal level, which is required to higher cognitive levels. This conclusion have implications that the unit of a buoyant force have to be presented with concrete activities for majority of students who are in concrete and transitional levels.

• Journal of the Korean School Mathematics Society
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• v.11 no.2
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• pp.315-335
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• 2008

This study is to recognize importance of casing anxiety on mathematics for underachievers and to examine a plan to solve a problem with anxiety, by analyzing factors which make underachievers anxious on the mathematics. First, we analyze factors which make mathematical underachievers anxious on the mathematics. Second, we compare and analyze a level of anxiety on the mathematics and factors which cause anxiety on the mathematics according to their grade and gender. This study's participants were 308 mathematical underachievers at 4th, 5th, and 6th grade, studying at six different elementary schools in three different areas. The results of factors which make mathematical underachievers anxious on the mathematics obtained from the survey are as follows. First, in the top-category factor, mathematical underachievers are influenced by following factors in order, which are a mathematic subject, learner's attitude, environment, and a teacher. Second, in the factor of making students anxious on the mathematics according tn their grade, although the mathematic anxiety of students at 6th grade is higher than students at 4th and 5th grade, in the anxiety differences between the different grades. Third, in the factors which make the students anxious on the mathematics according to their gender, female students show more anxiety than male students. In summary, an anxiety of the underachievers at the elementary schools are different in the top and sub-category factor, according to their grades and their gender. It is shown that the underachievers feel more anxiety compared to normal elementary schools, and therefore the anxiety on the mathematics is one of the causes of under-achievement of the mathematics.

• Journal of Gifted/Talented Education
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• v.20 no.3
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• pp.743-765
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• 2010

The purpose of this study was to provide and analyze the fundamental data on leadership skills and to analyze leadership skills among giftd elementary students according to grade, subject and gender. The main research questions in order to achieve the purpose of research are as follow. First, are there any differences of gifted elementary students' leadership skills in gifted groups? Second, do leadership program have an effect on improvement of gifted elementary students' leadership skills? The subjects for this study were 488 gifted elementary in 4th-6th grade in Busan. The students in the experiential group went thought 16 session do leadership program. After that, they had pre-tests and post-tests. the devices used to verify the effectiveness of the program were leadership skill scales. For this research analysis, MANOVA was used to investigate the first research questions and MANCOVA was used to investigate the second research question. Results from this study are as follows. Firstly, students in higher grades received fewer leadership skills points. This fact suggests that the leadership programs from the fourth grade should be implemented in 5th and 6th grade gifted education as well. Secondly, in the analysis of the results from gifted mathematics and gifted science, little significant statistical difference was shown. Thirdly, the analysis of leadership skills according to gender showed statistical significance. Finally, the study showed that the leadership education program had a positive effect. So the gifted 4th, 5th, and 6th grade students improve their leadership skills points by the end of the 16 week programs. Consequently, it is suggested that leadership education program on gifted elementary education was significant to improvement of leadership skills.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.812-825
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• 2019

Two dolomite samples mined from the different mines were calcined using a batch-type microwave kiln ($950/60min^{\circ}C$) to produce $CaO{\cdot}MgO$. The hydration of the $CaO{\cdot}MgO$ samples shows different reactivity. MgO was separated by reacting with a strong acid cation exchange resin using the reactivity of the hydration properties of light dolomite ($CaO{\cdot}MgO$). Calcium ($Ca-(R-SO_3)_2$) was separated from the prepared $CaO{\cdot}MgO$ by the cation exchange resin ($CaO{\cdot}MgO:R-SO_3H=1:12mass%$). High purity MgO (higher than 94 mass %) with unburned $CaCO_3$ (1~2 mass %) was obtained by the separation process. The separated MgO was heated at $950^{\circ}C$ for 60 minutes to afford high purity MgO with MgO content higher than 96%. And High-grade $CaCO_3$ was prepared from the reaction with calcium adsorbed resin ($Ca-(R-SO_3)_2$) and NaOH, $CO_2$ gas.