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김태민,김서경,황인남,황윤찬,강병철,윤숙자,이재서,오원만 대한치과보존학회 2009 Restorative Dentistry & Endodontics Vol.34 No.1
This study was performed to assess the radiopacity of a variety of root canal sealers according to the Specification concerning root canal sealers. Ten materials including Tubli-Seal™, Kerr Pulp Canal Sealer™, AH 26^(R), AH plus^(R), AH plus jet™, Ad seal™, Sealapex™, NOGENOU™, ZOB seal™, Epiphany™, and dentin were evaluated in this study. In the first part. densitometric reading of an each step of aluminum step wedge on occlusal film was performed at different voltage and exposure time. In the second part, ten specimens were radiographed simultaneously with an aluminum step wedges on the occlusal films under decided condition. The mean radiographic density values of the materials were transformed into radiopacity expressed equivalent thickness of aluminum (mm Al). The following results were obtained 1 Among the various conditions, the appropriate voltage and exposure time that meet the requirement density was 60 kVp at 0.2 s 2 All of the materials had greater radiopacity than 3 mm Al requirement of ANSI/ADA specification No. 57 (2000) and ISO No. 6876 (2001) standards. 3 The radiopacity of materials increased as thickness of materials increased. 4 The mm Al value of each specimen at 1mm in thickness has a significant difference in the statistics. It suggests that root canal sealers have a sufficient radiopacity that meet the requirement. 다양한 근관전색제는 방사선 사진상 주위 해부학적 구조와 구별될 만한 방사선 불투과성을 나타내야 한다 따라서 이런 물질들이 근관에 충전될 때의 방사선 불투과성 정도를 평가해야 할 필요성이 대두되고 있다. 본 실험에서는 다양한 근관전색제들의 방사선 불투과성을 평가하고자, 방사선 노출조건에 따른 aluminium step wedge에 대한 광학 밀도를 알아보고, 그 중 적절한 노출조건을 선택하여 수종의 근관 전색재의 방사선 불투과성 정도를 알루미늄 두께로 환산하여 비교해 보고자 한다. 방사선 불투과성의 기준을 위해 11개의 step으로 구성된 aluminum step wedge을 사용하여, 60kVP, 70kVp관전압 상태에서 각각 0.2, 0.3, 0.4초 그리고 0.2, 0.3, 0.33초의 꼭 노출시간으로 교합필름상에서 방사선 촬영후 적절한 노출 조건을 구하였다. 직경 5mm 각각의 두께 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm인 10종 (Tubli-Seal™, Kerr pulp Canal Sealer™, AH26^(R), AHplus^(R), AH plus jet starter kit™, Ad seal™, Sealapex™, Nogenol root canal sealer™, ZOB seal™, Epiphany™)의 근관전색재 시편을 각 재료와 두께당 10개씩 제작한 후, 동일한 두께의 상아질 시편, aluminum step wedge와 함께 정해진 노출시간에 따라 방사선 촬영을 하였다. 모든 필름은 자동현상기로 현상하였다. 시편의 방사선 흑화도를 densitometer로 5회 반복 측정 후, 평균값을 구하여 알루미눔 두께로 환산하였다.얻어진 정보를 분석하여 다음의 결과를 얻었다. 1 관전압 60 kVp에서 노출시간 0.2, 0.3, 0.4초, 70 kVp에서 0.2, 0.3, 0.33초로 변화를 주어 방사선 촬영을 하였을 때 흑화도가 ISO No. 6876 규격에 가장 적합한 것은 60 kVP, 0.2초 일 경우였다. 2 측정된 근관 전색제의 방사선 불투과성은 2.29 mm Al (N0GEN0L)로부터 13.69 mm Al (AH Plus jet)까지 다양하게 나타났으나, 모두 ANSI/ADA specification (2000) 또는 ISO No. 6876 (2001) 규격이 제시한 최소한 3mm Al 이상의 방사선 불투과성을 지녀야 한다는 기준에 적합하였다. 3 재료의 두께가 증가할수록 방사선 불투과성은 증가하지만, 정비례하지는 않았다. 4 각 실험재료의 1 mm 두께의 시편에 대한 mm Al값들은 통계적으로 유의한 차이가 있었다. 이상의 결과는 본 실험에 사용된 수종의 근관 전색재는 모든 규격에 적합한 방사선 불투과성을 가지고 있음을 시사한다.
김종신,조춘석,원찬희 全北大學校 附設 都市및環境硏究所 1997 都市 및 環境硏究 Vol.12 No.1
The purpose of this paper is to decide the ratio mixture between microbes and the most suitable material in order to immobilize white rot fungus. It shows that white rot fungus favorably lives, regarding to respiration speed and activity when pellet is immobilized by PVA. In addition, it survives better with sodium alginate, concerning about the rate of swelling. When PVA-frozen method is applied, methylene blue is decolorized 100% by immobilized Trametes versicolor and 90% by immobilized Irpex lacteus after 44hr. As a result, pellet immobilized by PVA, which indicates better mechanical stability and declororization rate, is superior to sodium alginate. The mixture rate between microorganisms and PVA is 1:1.
김형진,박찬규,김영석 충남대학교 산업기술연구소 2005 산업기술연구논문집 Vol.20 No.1
Owing to the mass-housing policies of high-density and high-rise, the residential environments in Korea have come to be uniform and monotonous. Nevertheless, the design competitions introduced for the first time in 1980s have played significant roles in developing the fresh ideas and concepts in housing design. And in our country, the land of gradient 0-9 ˚ that is able to plan as level sites come up to 32.5% of the total land and the land of the gradient 10-29 ˚ that should be designed by considering the characteristics of the sloping sites is 53.2% of the whole. For that reason, the development of the apartment housing in the sloping site has been done largely to solve the issues associated with the scarcity of the land. Therefore, it is very meaningful job to see the various design methods on the basis of the characteristics of the sites, particularly gradient, by analyzing the prizewinners in the design competitions. In this context, the research analyzed the works that won the design competition after 1990, and organized the types of the block plans and the design characteristics applied in our residence housing. Secondarily, it classified that types by the gradient and analyzed statistically and compared the numerical value.
ESPI 기법에 의한 하중을 받는 균열 박판의 진동 특성에 관한 연구
김경석,강기수,최지은,박찬주,홍진후 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.2
대부분의 실제구조물은 인장과 진동 등이 동시에 작용하는 복합하중 상태가 되며 이러한 환경에서 물체의 거동을 해석하는 것이 중요하다. 이 논문에서는 χ축에 대해 45˚결함이 있는 평판이 하중을 받고 있을 때, 진동 특성을 시간평균 electro speckle pattern interferometry(ESPI)를 이용하여 해석하였다. 결함이 있는 박판 시험편에 인장력을 증가하면서 물체의 고유진동수 변화와 모드의 형태 변화를 동시에 관찰하였다. 실험결과에서 결함은 저차모드에서는 진동모드에 영향을 주지 않았으나, 고차모드에서는 진동모드에 변화를 주었으며, 특정 진동모드에서 결함의 영향으로 현저하게 고유주파수가 낮아지는 경향을 보였다. 또한 실험결과는 유한요소해석과 비교하여 주파수 비교에서는 5%이내의 오차율을 보였으며, 진동모드 비교에서는 완전히 일치하였다. This paper presents the vibration characteristics of a rectangular plate with 45˚ oblique crack subjected to a uniaxial tension. The experiment is adopted by the time-average Electronic Speckle Pattern Interferometry(ESPI) method. The natural frequency and mode shape are considered accurately according to the increase of tensile load. When tensile load is zero, the vibration modes are agreed with the smooth and the 45˚ obliquely cracked plate. But according to the increasement of load, it is shown that vibration modes are extremely varied. The effects of the crack under the vibration are discussed in detail. It is indicated that the increase of load makes the variation of the frequencies and modes complicate in the range of even a small load. The results are agreed with the FEM analysis within 5%.
PbTiO₃ 강유전체 박막 제작과 유전율 특성에 미치는 Photon Energy 영향
김병인,송찬일,김창석 조선대학교 에너지.자원신기술연구소 2001 에너지·자원신기술연구소 논문지 Vol.23 No.2
This study evaporates PbTiO₃ layer thickness differently with RF sputtering method on Si Wafer(n-100). This study is performed to examine the characteristics of photon energy and dielectric loss according to the thickness of PbTiO₃ and increase the reliability and reproduction of PbTiO₃ thin film. It is confirmed that the variation of electric Constant by frequency is resulted from the formation of particles within thin film, the particle size and the polarization on grain boundary. Peak of electric Constant value of thin film has slower and less value in early low wavelength by the coulomb force involved in carrier combination according to the increase of frequency. Reversal of electric constant values is induced by dipole polarization shown in the dielectric of thin film. Complex electric constant ( ε1 , ε2) has larger peak values as its thickness is thinner and then it is larger according to the increase of frequency. Electric constant by photon energy has large value in imaginary number and is reduced exponentially by the increase of carrier density according to that of photon energy.