• Restorative Dentistry and Endodontics
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• v.30 no.1
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• pp.58-65
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• 2005

The purpose of this study was to compare the shaping ability of the three $ProTaper^{(R)}$ instrumentation techniques in simulated canals. Thirty resin blocks were divided into 3 groups with 10 canals each. Each group was instrumented with manual $ProTaper^{(R)}$ (Group M), rotary $ProTaper^{(R)}$ (Group R), and hybrid technique (Group H). Canal preparation time was recorded. The images of pre- and post-instrumented root canals were scanned and superimposed. The amounts of canal deviation, total canal width, inner canal width, outer canal width and centering ratio were measured at apical 1, 2, 3, 4, 5 and 6 mm levels 1. Canal preparation time was the shortest in R group (p < 0.05). 2. The amounts of total canal width in R group was generally larger than the other groups, but no significant differences were observed except at the 1, 3 mm levels (p > 0.05) .3. The amounts of inner canal width in R group was larger than M group at the 1 mm level and H group was larger than R group at the 6 mm level (p < 0.05). The amounts of outer canal width in R group was larger than H group only at the 1 mm level (p < 0.05). 4. The direction of canal deviation in H, R group at the 1, 2, 3 mm levels was outward and that in M group at the 1, 2 mm levels was inward. The amounts of canal deviation in H group was larger than R group at the 6 mm level (p < 0.05). 5. The amounts of centering ratio in H group was larger than R group at the 6 mm level (p < 0.05).

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.758-767
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• 1995

The purpose of this study was to evaluate canal shaping ability after canal preparation by using engine-driven nickel-titanium file and endosonic file in curved canals. 30 mesiobuccal canals of molars extracted within recent 3 months were divided into 3 groups. Group I and group II were prepared by using engine-driven nickel-titanium Gates-Glidden drill type and the engine-driven nickel-titanium file type. Group III prepared by using en do sonic file. The image of preinstrumented canals was taken by X-ray. The image of postinstrumented canal was taken by X-ray in the same condition of preinstrumentation. A magnified X-ray image on magnifier screen was traced and then compared the preinstrumentated canal image with the postinstrumentated canal image by superimposing method. The following results were obtained : 1. In the change of canal curvature, the engine-driven nickel-titanium Gates-Glidden drill type showed the least change and the ultrasonically filing showed the greatest change. 2. In the percentage of canal enlargement, the engine-driven nickel-titanium file type was greatest at all level(p<0.05), the apex of all group was the greatest, the difference of ultrasonically filing group showed greater between apex and cervix. 3. The percentage of canal enlargement on convex side was greater than that of on concave side in apex of each group(p<0.05). In the ultrasonically filing group, both sides of canal enlargement showed sharply difference(p<0.01). 4. The percentage of canal enlargement on convex side was greater than that of on concave side in the third of cervix of the engine-driven nickel-titanium file type and the ultrasonically filling. The percentage of canal enlargement of convex and concave side in the third of middle of the engine-driven nickel-titanium Gates-Glidden drill type show a similar canal enlargement between convex side and concave side. As above result, the engine-driven nickel-titanium file type was greater in canal enlargement than the other instruments. The engine-driven nickel-titanium Gates-Glidden dirll type was efficient endodontic instrument for curved canal preparation because it was least change in canal curvature.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.3
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• pp.150-157
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• 2002

A nonlinear shaping method for a wire antenna is presented to improve the limited pulse radiation ability due to the frequency characteristics with nulls which are found in the conventional straight or V antennas. The developed scheme is based on the minimization of frequency-dependence of the radiated electric field intensity over wide band, hence giving the ripple-type frequency characteristics. It is shown that the synthesized shape has more advantage in the case of shorter pulse. That is, we found that for shorter pulse exciting, the radiated peak value of the synthesized antenna is larger than that of the conventional linear antenna. The inverse discrete Fourier transform based on the moment method is used for the transient analysis of current distribution and far field electric field.

• Journal of the Korea Institute of Building Construction
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• v.15 no.2
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• pp.153-160
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• 2015

The marble powder is a by-product that can be freely collected during the manufacturing process of marble, such as sawing, shaping, and polishing. Disposal of this waste powder is one of the environmental problems worldwide today. Therefore, this study investigated to solve this problem by consuming the waste marble powder in high fluidity concrete, as a pore filler. For this purpose, the waste marble powder was used as a binder replacing 5%, 10%, 15%, and 20% of cement in high fluidity concrete. After mixing, slump flow test, time-to-reach the slump flow of 500mm test, O-lot test and U-box test were conducted with fresh concrete. For the hardened concrete, compressive strength was determined at the age of 28 days. According to the test results, the workability of high fluidity concrete increased with the powder of 15% replacement, and the compressive strength of high fluidity concrete also increased with the same amount of powder.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.6
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• pp.1519-1523
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• 2003

Glehnia littoralis Fr. Schmidt (Umbelliferae) is a short-lived herbaceous species that are mostly distributed throughout East Asia. Although G. littoralis has been regarded as ecologically important one, there is no report on population structure in Korea. Starch gel electrophoresis was used to investigate the allozyme variation and genetic structure of Korean populations of this species. A high level of genetic variation was found in G. littoral is populations. Nine enzymes revealed 18 loci, of which 12 were polymorphic (66.7%). Genetic diversity at the species and population levels were 0.159 and 0.129, respectively. The sexual and asexual reproduction, high fecundity, and colonization process are proposed as possible factors contributing to genetic diversity. An indirect estimate of the number of migrants per generation (Nm = 1.45) indicated that gene flow was not extensive among Korean populations of this species. It is suggested that the ability of vegetation and artificial selection may have played roles in shaping the population structure of this species. we recommend that a desirable conservation population should be included at least 30 plants per population and especially those with high variation.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.572-577
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• 2010

Reaction-bonded $Si_3N_4$ has cost-reduction merit because inexpensive silicon powder was used as a start material. But its density was not so high enough to be used for structural materials. So the sintered reaction-bonded $Si_3N_4$techniques were developed to solve the low density problem. In this study the sintered reaction-bonded $Si_3N_4$ manufacturing method by using polymer precursor which recently attained significant interest owing to the good shaping and processing ability was proposed. The formations, properties of reaction-bonded $Si_3N_4$ from silicon and polysilazane mixture were investigated. High density reaction-bonded $Si_3N_4$ was manufactured from silicon and silicon-containing preceramic polymers and post-sintering technique. The mixtures of silicon powder and polysilazane were prepared and reaction sintered in $N_2$ atmosphere at $1350^{\circ}C$ and post-sintered at 1600~$1950^{\circ}C$. Density and phase were analyzed and correlated to the resulting material properties.

• English Language & Literature Teaching
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• no.3
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• pp.231-248
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• 1997

With the trend of globalization more people are absorbing in the English learning programs. Not a few attend even the English-Korean translation training course to be semi-professional translators, but we English teachers have already experienced that it is not so easy to translate any language into another, and that it is far more difficult to translate poetry. Much time has been devoted to investigating the problems of translating poetry than any other mode. Poetry translation theory is concerned with the problem of faithfulness to the original poetry. To be a good translator we must fully understand the sound and sense of the original work. But when in translating English poetry into Korean we feel keenly our limits of understanding the sound and style of English poetry, and of expressing them into Korean. Even our sense-oriented translation is far from satisfactory. We often make quite a few mistranslation. Another immediate problem is that of alternation between word-for-word translation and free translation method, but first of all, we should have a perfect knowledge and understanding in English, and a good command of our mother tongue. We should also have a sound interpretation ability because poetry translation is based on the interpretation of the original, and on the shaping of that interpretation. Some doubts have been raised over the feasibility of poetry translation. They say it is not possible to combine in another language the emotion, the form, the style, the musical devices of English poetry. Yet the art of translation has been practiced everywhere in the world. Through this art we can share our experience and culture with foreigners and theirs with us.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.909-918
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• 2020

This study, not only investigates the important role of lifelong learning in shaping young people's knowledge and in maximizing their potential, but also aims to shed light on the influencing factors of lifelong learning of young people in Vietnam. The author applied STATA and SPSS to analyze quantitative data collected from questionnaires with 332 respondents aged between 19 years old and 24 years old. Based on a holistic review of literature, this study concludes that four driver factors affect young people's lifelong learning ability, comprising: organizational culture, motivation, human resource development, and domestic private type of enterprise. The results emphasize the positivity of organizational culture, human resource development, and the nature of work, especially organizational culture and human resource development, which are dominant reasons for young people to maintain lifelong learning. The relationship between demographics and lifelong learning was tested and it indicated that male has a stronger interest in learning than female. The result of the study also shows the impact of different types of business sectors on employees' learning intentions. It points out that the domestic private type of enterprise is the most effective factor that has a positive relationship with the lifelong learning of the individual.

• Journal of the Korean Ceramic Society
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• v.43 no.8 s.291
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• pp.472-478
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• 2006

The effect of compositional and processing variables on a nitriding reaction of silicon powder compact and subsequent post sintering of RBSN (Reaction-Bonded Silicon Nitride) was investigated. The addition of a nitriding agent enhanced nitridation rate substantially at low temperatures, while the formation of a liquid phase between the nitriding agent and the sintering additives at a high temperature caused a negative catalyst effect resulting in a decreased nitridation rate. A liquid phase formed by solely an additive, however, was found to have no effect on nitridation for the additive amount used in this research. The original site of a decomposing pore former was loosely filled by a reaction product ($Si_3N_4$), which provided a specimen with nitriding gas passage. For SRBSN (Sintered RBSN) specimens of high porosity, only a marginal dimensional change was measured after post sintering. Its engineering implication for near-net shaping ability is discussed.

• Korean Institute of Interior Design Journal
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• no.9
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• pp.98-107
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• 1996

The purpose of this study is to find out the characteristics of the office space as designed by Gwathemy Siegel and thereby to understand the current trend of interior design of working space in the United States. Unlike most architects, Gwathmey Siegel have extended themselves into interior designing of over twenty offices including law firms, financial institutions and design firms and have successfully won reputation as interior designers. They have distinguished themselves by their ability to turn up and take advantage of the possbility of shaping in a given structure. Their liberal use of fixed furniture and architectural lighting , in addition to ceilings and walls , set them apart from others in the field . The major design elements and principles of Gwathmey Siegel include, among others : 1) Curved and slanted walls on the floor plans endow the office space with forms. Fixed furniture and architectural lighting frequently serve as from -creating elements. 2) The openness of the reception and waiting areas and the irregularity of the corridor walls add a sense of variety in the office. 3) In terms of color and materials, subtle changes of texture and value and the various patterns of joint lines further enrich the space. 4) The principle of symmetry , rough or partial , as applied in the layout of rooms and furniture creates a sense of balance in the space.