• 한국전기화학회:학술대회논문집
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• 2000.10a
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• pp.37-37
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• 2000

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.4
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• pp.607-614
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• 1996

Nasal bone fracture is common in mid-facial trauma patients. In these patients, facial bone and nasal bone fracture are reducted at same time, but definite nasal reduction is difficulty in these patients because of nasotracheal intubation during general anesthesia and facial swelling in early facial trauma patients. If nasal packing and MMF are needed, there are difficult to maintain the reducted nasal bone because of some difficulty in airway maintenance after nasal packing and increasing the patient discomfort. So postoperative nasal deformity is more common in these combined patients. Secondary rhinoplasty is necessary in these patients who have deformed nasal bone, and there are many methods and materials for secondary rhinoplasty. But if primary nasal bone was reducted symmetrically, it is easy in secondary rhinoplasty. We present 7 cases of secondary rhinoplasty in mid-facial trauma patients who had combined nasal bone fracture. In these patients, primary nasal bone reduction carried with closed reduction method during primary facial bone reduction. About 6 months later, we performed secondary rhinoplasty with iliac bone and alloplastic materials. So we report these cases with literatures.

• Journal of The Korean Association For Science Education
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• v.42 no.6
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• pp.579-595
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• 2022

This study is a qualitative case study of secondary science teachers who are doing educational activities in YouTube. In particular, this study attempts to interpret this case based on Foucault's concept of 'Heterotopia', which means a space that allows for private freedom or deviance by reflecting various utopias without the norms and constraints from every day or real space. Five secondary science teachers who voluntarily opened a personal channel on the YouTube platform and actively uploaded their own videos related to science education participated in the study. In order to understand the experiences of five secondary science teachers, data were individually collected through semi-structured in-depth interviews, and the collected data were analyzed using qualitative case study method. For valid interpretation of the study, we also referred to the video contents, teacher training materials, and teaching and learning materials produced by the participants. As a result of the study, seven themes were revealed: 'Desire for one's own unique educational activities,' 'Youtube as an extended classroom space,' 'Expanded network of relationships beyond the classroom barrier,' 'Satisfaction of desire for recognition and experience of identity as a YouTuber,' 'Tension between the educational space and the YouTube,' 'Space to be reborn as a craftsman,' and 'Finding one's own direction as a Teacher-YouTuber.' Given those findings, we found that the identity and desire of secondary science teachers, which were limited in the existing secondary schools and classrooms, was expanded in a new space called YouTube. In addition, we suggested that YouTube could be a space where science teachers can realize their own ideals and feel the joy. And simple regulating teacher's behavior in Youtube space only based on norms and standards shared in traditional educational space would rather hinder their healthy construction of identity and growth.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.467-474
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• 1999

Objectives: Cytogenetic investigations were carried out on 770 women with primary (n=560) and secondary amenorrhea (n=210) to determine the frequency of chromosomal or genetic causes of amenorrhea. Materials and Methods: In 770 women with primary amenorrhea (n=560) and secondary amenorrhea (n=210), chromosomal analysis were performed. Results: 1) The most prevalent age group is 16-20 years of age group with primary amenorrhea and 26-30 years of age group with secondary amenorrhea. 2) Out of 560 cases of primary amenorrhea, 343 cases (61.3%) had the normal chromosome constitution and 217 cases (38.7%) had the abnormal chromosome constitution including 46,XY. 3) In 217 cases of abnormal chromosome of primary amenorrhea, 57 cases (26.3%) had 45,X and 34 cases (15.8%) had the 46,XY, 24 cases (11.0%) had 45,X/46,X,i (Xq), 23 cases (10.6%) had 45,X/46,X,+mar and 14 cases (6.6%) had 45,X/46,XY. 4) Out of 210 cases of secondary amenorrhea, 181 cases (86.2%) had the normal chromosome constitution and 29 cases (13.8%) had the abnormal chromosome. 5) In 29 cases of abnormal chromosome of secondary amenorrhea, 7 cases (24.1%) had 45,X/46, X,i (Xq), 4 cases (13.8%) had 45,X/46,XX. Conclusion: High percentage of chromosomal abnormalities was diagnosed in primary amenorrhea and most of them were sex chromosome anomalies. In secondary amenorrhea, the prevalence was lower than primary amenorrhea, so a preselection of patients with secondary amenorrhea for cytogenetic investigations seems to be necessary.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.161-167
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• 2018

In this study, transition metal coated carbon nanofibers (CNFs) were synthesized and applied as anode materials of Li secondary batteries. CNFs/Ni foam was immersed into 0.01 M transition metal solutions after growing CNFs on Ni foam via chemical vapor deposition (CVD) method. Transition metal coated CNFs/Ni foam was dried in an oven at $80^{\circ}C$. Morphologies, compositions, and crystal quality of CNFs-transition metal composites were characterized by scanning electron microscopy (SEM), Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS), respectively. Electrochemical characteristics of CNFs-transition metal composites as anodes of Li secondary batteries were investigated using a three-electrode cell. Transition metal/CNFs/Ni foam was directly employed as a working electrode without any binder. Lithium foil was used as both counter and reference electrodes while 1 M $LiClO_4$ was employed as the electrolyte after it was dissolved in a mixture of propylene carbonate:ethylene carbonate (PC:EC) at 1:1 volume ratio. Galvanostatic charge/discharge cycling and cyclic voltammetry measurements were taken at room temperature using a battery tester. In particular, the capacity of the synthesized CNFs-Fe was improved compared to that of CNFs. After 30 cycles, the capacity of CNFs-Fe was increased by 78%. Among four transition metals of Fe, Cu, Co and Ni coated on carbon nanofibers, the retention rate of CNFs-Fe was the highest at 41%. The initial capacity of CNFs-Fe with 670 mAh/g was reduced to 275 mAh/g after 30 cycles.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.121-125
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• 2006

[ $LiFePO_4$ ] is one of the promising materials for cathode material of secondary lithium batteries due to its high energy density, low cost, environmental friendliness and safety. $LiFePO_4$ was synthesized by the solid-state reaction method at 500 - 800°C. The crystal structure of $LiFePO_4$ was analyzed by X-ray powder diffraction. The samples synthesized at 600 and $700^{\circ}C$ showed a single phase of a olivine structure. The particle sizes were increased and the specific surface areas were decreased with heating temperatures. The electrochemical performance was investigated by coin cell test. The discharge capacities at 0.1 C-rate were 118 mAh/g and 112 mAh/g at $600^{\circ}C,\;700^{\circ}C$, respectively. In an attempt to improve the electrical conductivity of cathode materials, $LiFePO_4/graphite$ composite was prepared with various graphite contents. The electrical conductivity and discharge capacity were increased with increasing the graphite contents in composite samples. The rate capabilities at high current densities were also improved.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.59-64
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• 2008

The mechanical properties of liquid phase sintered (LPS) SiC materials, with the addition of oxide powder, were investigated, in conjunction with a detailed analysis of their microstructures. LPS-SiC materials were fabricated at a temperature of 1820 $^{\circ}C$ under an argon atmosphere, using three different starting sizes of SiC particles. The sintering additive for the fabrication of the LPS-SiC materials was an $Al_2O_3-Y_2O_3$ mixture with a constant composition ratio ($Al_2O_3/Y_2O_3$: 1.5). The particle sizes of the commercial SiC powderswere 30 nm, 0.3 $\mu$m, and 3.0 $\mu$m. The flexural strength of the LPS-SiC materials was also examined at elevated temperatures. A decrease in the starting size of the SiC particles led to an increase in the flexural strength of the LPS-SiC materials, accompanying a highly dense morphology with the creation of a secondary phase. Such a secondary phase was identified as $Y_3Al_2(AlO_4)2$. The flexural strength of the LPS-SiC materials greatly decreased with an increase in the test temperature, due to the creation of a large amount of pores.

• Korean Journal of Materials Research
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• v.25 no.6
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• pp.279-287
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• 2015

In order to prepare anode materials for high power lithium ion secondary batteries, carbon composites were fabricated with a mixture of petroleum pitch and coke (PC) and a mixture of petroleum pitch, coke, and natural graphite (PC-NG). Although natural graphite has a good reversible capacity, it has disadvaantages of a sharp decrease in capacity during high rate charging and potential plateaus. This may cause difficulties in perceiving the capacity variations as a function of electrical potential. The coke anodes have advantages without potential plateaus and a high rate capability, but they have a low reversible capacity. With PC anode composites, the petroleum pitch/cokes mixture at 1:4 with heat treatment at $1000^{\circ}C$ (PC14-1000C) showed relatively high electrochemical properties. With PC-NG anode composites, the proper graphite contents were determined at 10~30 wt.%. The composites with a given content of natural graphite and remaining content of various petroleum pitch/cokes mixtures at 1:4~4:1 mass ratios were heated at $800{\sim}1200^{\circ}C$. By increasing the content of petroleum pitch, reversible capacity increased, but a high rate capability decreased. For a given composition of carbonaceous composite, the discharge rate capability improved but the reversible capacity decreased with an increase in heat treatment temperature. The carbonaceous composites fabricated with a mixture of 30 wt.% natural graphite and 70 wt.% petroleum pitch/cokes mixture at 1:4 mass ratio and heat treated at $1000^{\circ}C$ showed relatively high electrochemical properties, of which the reversible capacity, initial efficiency, discharge rate capability (retention of discharge capacity in 10 C/0.2 C), and charge capacity at 5 C were 330 mAh/g, 79 %, 80 %, and 60 mAh/g, respectively.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.2
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• pp.135-168
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• 2015

This study intends to design a curation system to support elementary and secondary schools for reusing and sharing instructional materials efficiently. It is proved through interviewing teachers at the chalkface that they utilize instructional materials, and there are some differences between elementary schools and secondary schools about the media for creating the instructional materials, and the purpose of using them. The functional requirements of curation system for reusing and sharing instructional materials are derived from questionnaires. The investigation of the existing curation systems was conducted to identify the strategies for policy, design, standard, and tools for effective operation of the digital curation system. The tasks and the functions of the curation system designed by reflecting the results of this study are as following. The tasks related to individual workspace include 'authentication', 'system configuration', 'registration' of created materials, 'material keeping' for the individual, and 'reusing (editing)'. The tasks related to sharing workspace contain 'receiving' for sharing, 'archiving' for accessing, 'peer evaluation', 'accessing' through the retrieval, and 'bulletin board'.

• Journal of The Korean Association For Science Education
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• v.18 no.3
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• pp.443-450
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• 1998

This study was performed to find the environmental factors of inquiry instruction perceived by secondary school science teacher. The instrument consisted of three domains such as teaching conditions, viewpoints of secondary school science teachers of environmental factors for inquiry instruction, and barrier and improve! rent factors of inquiry instruction. Teaching conditions between middle school and high school science teachers were not different significantly. Environmental factors of inquiry instruction of secondary school science teacher included five factors such as 'facilities and encouragement', 'amount of works and materials', 'teacher education and textbook', 'practice and knowledge' and 'perception of necessity and satisfaction'. And all factors except 'perception of necessity and satisfaction' were very low state for inquiry instruction. In the disturbant and improving factors, the critical factors were 'over students per class', 'textbook' and 'learning materials' for middle school science teachers, and 'over students per class', and 'entrance examination' for high school science teachers. Thus the development and diffusion of adequate inquiry learning materials may be helpful to practicing inquiry instruction as decrease of works and psychological charges, and it is needed to reorganize systematically and intensify pre- and in-service teacher education to practice inquiry instruction.