• Restorative Dentistry and Endodontics
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• 제30권1호
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• pp.58-65
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• 2005

이 연구의 목적은 만곡이 삼한 근관에서 $ProTaper^{(R)}$를 수동으로 사용하는 방법, 엔진 구동으로 사용하는 방법, 그리고, 치관부는 엔진 구동으로 치근단부는 수동으로 사용하는 세 가지 방법의 근관 성형 능력을 비교하기 위한 것이다. 근관 길이가 170mm이고 근관 입구에서 10mm 떨어진 부위에서 만곡이 시작되며 평균 40도의 단일 만곡을 가지는 투명한 레진 블락 30개를 사용하였다. 각 군당 10개의 레진 블락을 사용하였으며, 수동형 $ProTaper^{(R)}$로 전체근관을 성형한 군형 M군, 엔진 구동형 $ProTaper^{(R)}$로 전체근관을 성형한 군을 R군, 근단부는 수동형 $ProTaper^{(R)}$를, 치관부는 엔진 구동형 $ProTaper^{(R)}$를 사용하여 성형한 군을 H군으로 하였다. 각각의 블락을 성형하고 각 군별 근관 성형시간을 기록하였다. 근관 성형전과 후의 이미지를 중첩하여 근단공으로부터의 수직 이동 거리 1, 2, 3, 4, 5 그리고 6 mm 위치에서 수평선을 긋고 총 근관폭경, 근관 만곡 내외측 삭제량, 근관의 변위, 중심 이동률을 평가하여 다음과 같은 결론을 얻었다. 1. 근관 성형시간은 R군, H군, M군 순으로 짧았고, 세 군 사이에는 유의한 차이가 있었다(p < 0.05). 2. R군이 전체적으로 삭제량이 많은 경향을 보였으나, 1, 3 mm를 제외하고는 차이가 없었다(p > 0.05). 3. 만곡내측 삭제량에 있어서는 1 mm 지점에서는 R군이, 6 mm 지점에서는 H군이 컸지만 (p < 0.05), 나머지 지점에서는 차이가 없었다. 만곡외측 삭제량은 1 mm 지점에서만 R군이 컸다 (p > 0.05). 4. H군, R군은 1, 2, 3 mm 지점, M군은 1, 2 mm 지점에서 만곡외측으로의 변위를 보였고, 그 외의 지점에서는 내측변위를 보였다. 각 군 간의 변위차이는 6 mm 지점에서 H군이 컸다(p < 0.05). 5. 근관의 중심 이동률은 6 mm 지점에서 H군이 R군에 비해 유의하게 컸지만 다른 모든 위치에서는 차이가 없었다(p < 0.05). 본 실험결과를 토대로 할 때, 각 평가 항목에서 측정 위치에 따라 약간씩 차이가 있었으나, 중심 이동률은 대부분의 위치에서 유의한 차이가 없었다. 따라서 만곡 근관을 성형시에는 세 가지 방법 중 어느 것이 더 유용하다고 보기 어렵다고 판단된다.

• Restorative Dentistry and Endodontics
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• 제20권2호
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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.

• 대한전자공학회논문지TC
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• 제39권3호
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• pp.150-157
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• 2002

펄스 안테나로 많이 사용되는 종래의 직선형 혹은 V-형 안테나의 원거리전장은 null점들을 갖는 주파수 특성을 가지므로 제한된 펄스 복사 능력을 가진다. 이를 개선시키기 위해 비선형적 형상을 갖는 와이어안테나의 합성법을 제안하였다 즉, 복사 전장의 주파수 의존성을 최소화시키는 형상방정식을 유도하고 그 해를 산출하므로서 리플형의 광대역 특성을 갖는 형상을 합성하였다. 그 결과 매우 넓은 주요 스펙트럼을 갖는 짧은 펄스의 복사에 유리함을 보였다. 따라서, 펄스폭이 좁을수록 합성된 다이폴 안테나 특성이 종래의 선형 다이폴 보다 우수한 피크치를 갖는 펄스 복사가 이루어짐을 보였다. 전류 분포 및 원거리 전장의 과도해석을 위해 모멘트법에 기반한 역 이산 푸리에 변환을 사용하였다.

• 한국건축시공학회지
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• 제15권2호
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• pp.153-160
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• 2015

본 연구는 대리석가공과정에 발생하는 부산물인 폐 대리석 분말을 고유동 콘크리트의 유동성, 충전성 및 강도특성에 어떠한 영향을 주는지를 분석하였다. 실험결과, 폐 대리석 분말을 혼입한 굳지 않은 고유동 콘크리트 특성을 살펴보면 유동성이 증가하였고, 재료분리 저항성, 충전성이 우수하였다. 또한 경화한 고유동 콘크리트에서 압축강도는 폐 대리석 분말의 치환율 15%까지 모든 재령에서 압축강도가 증가하여 폐 대리석 분말의 최적 치환율은 15% 이내가 적정할 것으로 판단된다. 이상의 실험결과를 바탕으로 폐 대리석 분말을 고유동 콘크리트의 충전재로 활용하면 산업부산을 활용할 수 있어 환경오염방지와 콘크리트 제조시 원가절감의 이점을 동시에 달성할 수 있을 것으로 판단된다.

• 동의생리병리학회지
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• 제17권6호
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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.

• 한국세라믹학회지
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• 제47권6호
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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.

• 영어어문교육
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• 제3호
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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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• 제7권10호
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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.

• 한국세라믹학회지
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• 제43권8호
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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.

• 한국실내디자인학회논문집
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• 제9호
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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.