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LIGA 공정에서의 노광시간과 X선마스크 흡광체의 두께
길계환(Kye-Hwan Gil),이승섭(Seung-Seob Lee),염영일(Young-Il Youm) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.2
감광체 내부에서 감쇠된 X선 에너지는 그 영역에 그대로 축적된다고 가정함으로써, LIGA X선노광 단계를 3 개의 부등식으로 모델링하였다. 그로부터 양질의 미세구조물을 얻기 위한 최소노광시간과 최대노광시간 그리고 X선마스크 흡광체의 필요두께에 관한 식이 구해졌다. 방사광의 에너지전달률 계산식이 소개되었으며, 이를 X선노광 단계에 적용하였다. 대표적 LIGA 감광체인 PMMA의 감쇠길이를 광자에너지의 멱함수로 근사시키고, 마스크흡광체에 도달하는 X선의 평균 광자에너지를 앞서 유도된 식들에 도입함으로써, 평균 광자에너지와 PMMA의 두께에 대한 최소노광시간과 최대노광시간의 추이를 예측하였으며, PMMA의 노광 가능한 최대두께에 관한 식을 구했다. 또한, 마스크흡광체에 입사하는 X선의 광자에너지와 PMMA의 두께에 대한 금 마스크흡광체 필요두께의 추이도 예측되었다. 최대노광시간은 동일 총에너지전달률 강도에 대하여 평균 광자에너지가 증가함에 따라 단조증가하며, 감광체의 두께의 함수가 아니다. 최소노광시간은 PMMA의 두께가 PMMA의 감쇠길이보다 작은 일반적인 LIGA 공정에서, 동일 총에너지전달률 강도에 대하여 평균 광자에너지가 증가함에 따라 증가하며, PMMA의 두께에 대해서는 단조증가한다. 감광체의 노광 기능한 최대두께는 평균 광자에너지에서의 감광체의 감쇠길이에 비례하며, 그 비례상수는 In(D_(dm)/D_(dv))이다. 금 마스크흡광체의 필요두께는 마스크흡광체에 입사하는 X선의 광자에너지에 대해서는 불규칙하게 증가하나, PMMA의 두께에 대해서는 완만한 증가세를 보이며, 총에너지전달률 강도 자체와는 무관하다. 유도된 여러 식의 단순성으로 인하여 노광시간, 마스크흡광체의 감쇠계수와 두께, 감광체의 감쇠계수와 두께, 그리고 방사광의 에너지전달률 강도 등의 상호연관성과 X선노광 현상에 대한 명확한 이해가 가능하였다. The LIGA X-ray exposure step was modelled into three inequalities, by assuming that the X-ray energy attenuated within a resist is deposited only in the localized range of the resist. From these inequalities, equations for the minimum and maximum exposure times required for a good quality microstructure were obtained. Also, an equation for the thickness of an X-ray mask absorber was obtained from the exposure requirement of threshold dose deposition. The calculation method of the synchrotron radiation power from a synchrotron radiation source was introduced and applied to an X-ray exposure step. A power function of photon energy, approximating the attenuation length of the representative LIGA resist, PMMA, and the mean photon energy of the X-rays incident upon an X-ray mask absorber were applied to the above mentioned equations. Consequently, the tendencies of the minimum and maximum exposure times with respect to mean photon energy and thickness of PMMA were examined and an equation for the maximally exposable thickness of PMMA was obtained. Additionally, the tendencies of the necessary thickness of a gold X-ray mask absorber with respect to thickness of PMMA and photon energy of the X-rays incident upon an X-ray mask absorber were examined. The maximum exposure time increases monotonically with increasing mean photon energy for the same total power density and is not a function of the thickness of resist. The minimum exposure time increases with increasing mean photon energy for the same total power density in the case of the general LIGA process, where the thickness of PMMA is thinner than the attenuation length of PMMA. Additionally, the minimum exposure time increases monotonically with increasing thickness of PMMA. The maximally exposable thickness of resist is proportional to the attenuation length of the resist at the mean photon energy, with its proportional constant of In (D_(dm)/D_(dv)). The necessary thickness of a gold X-ray mask absorber increases irregularly with increasing photon energy of the X-rays incident upon an X-ray mask absorber due to absorption edges of gold, increases smoothly with increasing PMMA thickness ratio, and is independent of the total power density itself. The simplicity of the derived equations has made clearly understandable the X-ray exposure phenomenon and the correlation among the exposure times, the attenuation coefficient and the thickness of an X-ray mask absorber, the attenuation coefficient and the thickness of the resist, and the synchrotron radiation power density.
김세동,인주철,안종철,염영일,이일기,안면환,추도식 대한골절학회 1991 대한골절학회지 Vol.4 No.1
The bone plate, nail and external fixation apparatus have been indtroduced for the union of the ftactured bones. Recently, the external fixation technique has been revived, especially for the healing of the fractured tibia, femur, pelvis and forearm bones. The device was intended to neutralize a comminuted fracture by provision of interfragmentary compression. Numerous different types of external fixation apparatuses have been developed in U.S.A. and other European countries. However, m our country, the apparatuses have been imported and utilized for the surgical application without any experimental confirmation. For the elucidation of the usage of imported external fixation devices, the stiffness of the extemal fixation devices (Orthofix, Monofixateure, and Hoffmann) were analyized experimentally. MTS and universal testing machine(UTM) were used for the experimental analysis under the different loading conditions of axial compression, antero-posterior and medio-lateral bending. Furthermore, the stiffness and yielding load of the laboratory developed unilateral type of external fixatian device were compared with those of the imported ones. In addition to this, the configuration of laboratory developed device was changed for the parametric study under the axial compression. The stiffness and yielding load of the laboratory developed device were sufficient for surgical application. However, the weight of our laboratory developed model is 1.2 times the average weight of imported ones. The reduction of weight may be needed for more convenient surgical application