• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.572-581
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• 2023

Purpose: The purpose of this study is to improve the irregularity of the stress-strain curve and to ensure accuracy when calculating the damping effect by preventing members from moving in the off-plane direction due to eccentricity when loads are applied. Method: The specifications of the steel strips used in this study are the same, but the curvature of the strips to constitute each damper is different. Each steel strip with different curvature was arranged in an triangle, three dampers with different curvature were made, and repeated load tests were conducted, and the amount of energy dissipation was calculated to measure the performance of the damper. Result: The amount of energy dissipation significantly decreases compared to the case where there is no initial curvature, and the change in the test energy dissipation amount according to the size of the curvature is not large, and the presence or absence of the hyperbolic rate is considered an important variable. Conclusion: The period is about 78.7% longer from T=0.3 to T=0.536sec, and the response spectrum acceleration is reduced from Sa=0.54g to Sa=0.229g, so the damping effect of the damper is sufficient.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.163-169
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• 2014

Purpose: This study is for compared the change of corneal refractive power before and after wearing of rigid gas permeable contact lense with diagnostic method which is 1 D flatter than alignment fitting on right eye and alignment fitting on left eye for 2 months and investigate the preference. Methods: Twenty middle school and high school students (40 eyes) who had never worn a contact lense before for no corneal topographical change, no ocular disease, no experience of ophthalmic surgery and have normal tear amount were selected for this study and corneal refractive power were examined before wearing rigid gas permeable contact lense and adaptation status and corneal examination were performed after 10 days of wearing and after cheking up the continuation of wearing, all candidate wear contact lens 8 hours per day for 2 month and corneal refractive power were compared. Results: After 2 months of wearing with 1 D flatter than the alignment fitting on right eyes, there was significant difference in the central corneal refractive power was $43.84{\pm}1.33D$, flat K power was $43.05{\pm}1.29D$, and steep K power was $44.61{\pm}1.42D$ decreased than before wearing (p<0.001, 0.001, 0.047). The e-value of the principal meridians also shows statistically significant difference (p=0.037, 0.015). After 2 months of wearing with alignment fitting on left eyes, the central corneal refractive power was $44.40{\pm}1.26D$, flat K power was $43.57{\pm}1.23D$. and flat K e-value was $0.58{\pm}0.05$ which showed no statistically significant difference (p = 0.769, 0.614, 0.181). But steep K power was $45.25{\pm}1.36$, and steep K e-value was $0.45{\pm}0.18$ which shows statistically significant difference (p=0.018, 0.027). Conclusions: Consider the comfort, clear vision, dryness for preference fitting investment, 6 students (30%) prefer right eye which is 1 D flatter fitting, 14 students (70%) prefer left eye which is alignment fitting. For rigid gas permeable fitting needed for accurate examination and should prescribe the alignment fitting which is suitable for each cornea.