• Korean Journal of Mathematics
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• 제25권4호
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• pp.513-535
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• 2017

As a continuation to the study in [8, 12, 15, 17], we construct bi-conservative central normal (BCN) and bi-conservative asymptomatic normal (BAN) ruled surfaces in Euclidean 3-space ${\mathbb{E}}^3$. For such surfaces, local study is given and some examples are constructed using computer aided geometric design (CAGD).

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.407-417
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• 2004

본 연구는 우라늄변환시설의 해체과정에서 발생되는 콘크리트 및 구성부품에 대한 알파분광과 감마분광에 대한 방사선계측방법의 타당성을 입증하고자 한다. 우라늄변환시설내의 구성부품 및 내부벽면은 천연우라늄 물질로 오염되어있다. 스테인레스 스틸 파이프와 벽면의 콘크리트의 일부에 대하여 시료를 채취하고 알파분석과 감마분석을 수행하였다. 천연우라늄 시료(AUC)의 측정에서 0.01 Bq/g 이상에서는 알파선 측정결과와 감마선 측정결과가 잘 일치하지만, 0.005 Bq/g의 낮은 농도에서는 감마선 측정결과가 상대적으로 높게 평가된다. 변환공정의 천연우라늄인 $^{238}U$은 $^{214}Pb$, $^{214}Bi$ 와 $^{234}Th$, $^{234m}Pa$을 비교 측정하여 그 농도를 구할 수 있다. 우라늄변환시설의 벽면은 대부분 우라늄으로 오염되어있다. 우라늄변환시설 해체과정에서 발생되는 배경방사능 준위의 폐기물을 감마분광법을 이용하여 계측하여 보수적인 평가 자료로 활용할 수 있다.

• The Journal of Advanced Prosthodontics
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• 제4권1호
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• pp.7-12
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• 2012

PURPOSE. Articulation paper mark size is widely accepted as an indicator of forceful tooth contacts. However, mark size is indicative of contact location and surface area only, and does not quantify occlusal force. The purpose of this study is to determine if a relationship exists between the size of paper marks and the percentage of force applied to the same tooth. MATERIALS AND METHODS. Thirty dentate female subjects intercuspated into articulation paper strips to mark occlusal contacts on their maxillary posterior teeth, followed by taking photographs. Then each subject made a multi-bite digital occlusal force percentage recording. The surface area of the largest and darkest articulation paper mark (n = 240 marks) in each quadrant (n = 60 quadrants) was calculated in photographic pixels, and compared with the force percentage present on the same tooth. RESULTS. Regression analysis shows a bi-variant fit of force % on tooth (P<.05). The correlation coefficient between the mark area and the percentage of force indicated a low positive correlation. The coefficient of determination showed a low causative relationship between mark area and force ($r^2$ = 0.067). The largest paper mark in each quadrant was matched with the most forceful tooth in that same quadrant only 38.3% of time. Only 6 2/3% of mark surface area could be explained by applied occlusal force, while most of the mark area results from other factors unrelated to the applied occlusal force. CONCLUSION. The findings of this study indicate that size of articulation paper mark is an unreliable indicator of applied occlusal force, to guide treatment occlusal adjustments.

• Smart Structures and Systems
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• 제17권4호
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• pp.593-610
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• 2016

In this study, an innovative and smart glass fiber-reinforced polymer (GFRP) hybrid bar was developed for stronger durability of concrete structures. As comparing with the conventional GFRP bar, the smart GFRP Hybrid bar can promise to enhance the modulus of elasticity so that it makes the cracking reduced than the case when the conventional GFRP bar is used. Besides, the GFRP Hybrid bar can effectively resist the corrosion of conventional steel bar by the GFRP outer surface on the steel bar. In order to verify the bond performance of the GFRP hybrid bar for structural reinforcement, uniaxial pull-out test was conducted. The variables were the bar diameter and the number of strands and pitch of the fiber ribs. Tensile tests showed a excellent increase in the modulus of elasticity, 152.1 GPa, as compared to that of the pure GFRP bar (50 GPa). The stress-strain curve was bi-linear, so that the ductile performance could be obtained. For the bond test, the entire GFRP hybrid bar test specimens failed in concrete splitting due to higher shear strength resulting in concrete crushing as a function of bar deformation. Investigation revealed that an increase in the number of strands of fiber ribs enhanced the bond strength, and the pitch guaranteed the bond strength of 19.1 mm diameter hybrid bar with 15.9 mm diameter of core section of deformed steel the ACI 440 1R-15 equation is regarded as more suitable for predicting the bond strength of GFRP hybrid bars, whereas the CSA S806-12 prediction is considered too conservative and is largely influenced by the bar diameter. For further study, various geometrical and material properties such as concrete cover, cross-sectional ratio, and surface treatment should be considered.