• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.418-419
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• 2008

관로에 케이블을 포설할 때에는 최대포설장력(Maximum Pulling Tension Factors)과 허용측압(Sidewall Bearing Pressure)이 고려되어야 한다. 최대포설장력은 케이블의 무게와 관로의 마찰계수에 의해 계산이 되고 관로의 경간에 의해 변화하게 된다. 측압은 관로의 곡률반경, 포설장력, 케이블 무게 등과 직접 관련이 있다. 관로의 곡률반경은 현장에서 도로의 길이와 현의길이, 호의 높이 등을 측정하여 구하기도 하고 도면상에서 계산에 의해 구하기도 한다. 곡률반경과 포설장력, 측압의 관계성을 비교해 보면 포설장력은 곡률반경의 영향을 거의 받지 않지만 측압은 곡률반경의 영향을 크게 받는다. 허용측압이상의 측압이 굴곡부에서 관로와 케이블사이에 발생하면 관로와 케이블이 손상되기 때문에 관로 설계시에는 측압을 반드시 고려하여야 된다.

• Composites Research
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• v.14 no.2
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• pp.22-32
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• 2001

Damage induced by low-velocity impact on the curved composite laminates was experimentally evaluated for CFRP cylindrical shells with the radius of curvatures of 50, 150, 300, and 500 mm. The result was then compared with that of flat laminates and with the results by nonlinear finite-element analysis. The radius of curvatures and the effective shell stiffness appeared to considerably affect the dynamic impact response of curved shells. Under the same impact energy level, the maximum contact force increased with the decreasing radius of curvatures, with reaching 1.5 times that for plates at the radius of curvature of 50 mm. Since the maximum contact farce is directly related to the impact damage, curved laminates can be more susceptible to delamination and less resistant to the low-velocity impact damage. Delamination was distributed rather evenly at each interface along the thickness direction of curved laminates on the contrary to the case of flat laminates, where delamination is typically concentrated at the interfaces away from the impact point. This implies that the effect of curvatures has to be considered for the design of a curved composite laminate.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.127-133
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• 2012

Perpose: The aim of this study is to investigate the measuring method in radius of eyeglasses lens curvature by using keratometer in noncontact method. Methods: A trial lens for vision test in diopter range from -9.00 D to -11.50 D were attached in front part of keratometer, after that we set eyeglasses lens at the place where eyeglasses lens is apart about 25 cm from front position of keratometer. We measured the radius of curvature from observation of clear mire image while the position of eyeglasses lens is changed in a small quantity. After that, we made some formulas for compensation of radius of curvature by using spherometer. Results: The radius of curvature was successfully measured by keratometer with trial lens in front part of it. The measured radius of curvature was changed to compensation value using spherometer data, and the 5 kind of linear equation to make compensation value was made. Any kind of lenses measured by using keratometer that trial lens was attached in front part of it, after that it was confirmed that the result of calculation from line equation is exact in error ratio below 3.5%. Conclusions: It was confirmed that radius of eyeglasses lens curvature can be measured by using keratometer by noncontact method, and the accuracy is higher than "lens measure".

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.2
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• pp.71-76
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• 1996

As the results of measurement of the radius of corneal curvature with keratometer, for the right eye of 91 male adults, horizontal radius is 7.16 mm to 8.49 mm and vertical radius is 7.03 mm to 8.34 mm, and for the left eye of male adults, horizontal radius is 7.10 mm to 8.48 mm and vertical radius is 7.01 mm to 8.24 mm. In case of 61 female adults, horizontal radius is 7.16 mm to 8.45 mm, vertical radius 7.11 mm to 8.18 mm for the right eye, and horizontal radius 7.15 mm 108.43 mm and vertical radius 7.01 mm to 8.26 mm for the left eye. The mean value of radius of corneal curvature is 7.74 mm for male and 7.69 mm for female. Also the mean value of horizontal radius is 7.79 mm and vertical radius is 7.64 mm. Overall mean value of the radius of corneal curvature is 7.71 mm that is corresponded to Gullstrand's eye. The horizontal radius is 0.15 mm bigger than vertical radius.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.405-410
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• 2005

In this paper, the front radiuses of curvature of spherical spectacle lenses in the cosmetic and optical point of view are investigated and are calculated using Zinken-Sommer condition. The optical power of all spherical spectacle lens shows good quality at the test using autometic lensmeter. However the front radiuses of curvature of spherical spectacle lenses are quite different depending on the lens companies. The front radius of curvature of those lenses is larger than that calculated using Zinken-Sommer condition. We know that the front radius of curvature of commercial spectacle lens is emphasized more cosmetic aspect than optical point of view.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.66-73
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• 2008

Present study examines the detonation wave propagation characteristics in annular channels. Numerical approaches used in the previous studies were extended with marching windows technique. Parametric study has been carried out using a radius of curvature normalized by the channel width considered as unique geometric parameter. In the channels of small radius of curvature, detonation wave is unstable and the regular cell structure is not observed. There is a critical radius of curvature where cell structure can be sustained. The effect of curvature makes the pressure difference on inner and outer surfaces where the detonation wave is overdriven. The results converge to that of straight channel as the radius of curvature gets larger, as expected.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.155-159
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• 2011

본 연구는 만곡수로 외측에 횡월류 위어를 설치하여 곡률반경에 대한 횡월류 유량계수의 특성을 분석하였다. 곡률반경의 변화에 따른 만곡부의 중심각이 180인 수로모형을 설계하였으며, FLOW-3D모형에 적용하여 유량계수를 산정하고 직선 수로와 비교하여 유량계수의 특성을 분석하는데 목적이 있다. 난류모형은 RNG-$\in$ 모형을 사용하였으며, 수치기법으로는 유한체적법을 사용하였다. 모형의 적용성 검정을 위해 기존에 연구되었던 수리실험과 동일한 조건의 수치모의를 수행하여 모형의 적용성을 확인하였다. 본 연구에서는 하폭를 고정시키고 곡률반경를 변화시킴으로써 $R_c/b$의 변화에 따른 유량계수(C)의 변화를 분석하고, 만곡수로의 월류량($Q_{wc}$)에 대한 직선수로의 월류량($Q_{ws}$)의 비, 만곡수로의 평균 월류 수심에 대한 직선수로의 평균 월류 수심($y_{cave}/y_{save}$)과 $R_c/b$의 관계를 분석하였다. 분석결과 유량계수는 상류수심, 월류량, 만곡수로의 곡률반경 등의 변화에 따라 유량계수는 변화하였으며, 직선과 만곡수로에 대해 분석을 수행하였기 때문에 직선수로의 영향인자를 이용하여 만곡수로에 설치된 횡월류 위어의 월류량과 유량계수를 추정 가능할 것이라 판단된다.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.3
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• pp.165-171
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• 2005

The aim of the study was to investigate the diameter and base curve changes of soft contact lens by protein deposition. Soft contact lenses were soaked in artificial tear or protein solution which had the same composition with tear for 2min, 10min, 30min, 1hr, 3hr, 6hr, 12hr, and 24hr. Diameter and base curve changes of soft contact lenses were examined by using the high speed camera(Fastcam ultima 1024). The longer the soaking time of soft contact lenses in the artificial tear, the diameter and base curve changes of soft contact lenses was more increased. In the case of soft contact lenses adsorbed only protein, the similar pattern was shown and the diameter and base curve were decreased. However, the influence of calcium ion was found to be less than that of protein. These results suggest that the tear protein causes the diameter and base curve decrease of soft contact lens, which might be related to the discomfort after soft contact lens wearing.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.181-185
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• 2006

The measurement of the radius of corneal curvature with keratometer was followed in 184 university students who wearing RGP contact lens and consisted of female(167), male(17) and keratoconus patients(3). Overall mean value in the radius of corneal curvature is 7.77mm, and right and left eyes is appeared the same mean value. Overall mean value in horizontal and vertical is 7.88mm and 7.65mm. Horizontal means is larger than vertical means by 0.22mm of the all female and male students. Male's mean value in the radius of corneal curvature(7.84mm) is larger than female's by 0.08mm, and right and left eyes is also the same mean value. Keratoconus patients' mean value in the radius of corneal curvature(6.86mm) is smaller than others students by 0.91mm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1729-1733
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• 2007

In this paper, we have carried out some tests for analyzing the effects of optical fiber characteristics and piping structures in designing a Customer Cabling System with optical fibers. In this tests, the loss characteristics due to the number of curvatures and the radius of curvature with bending to establish an optical fiber have analyzed particularly. We can confirm that the test results satisfy the current technical regulations in both cases of the number of curvatures and the radius of curvatures. Also, in particular, since there is no loss in an optical cable under the current radius of curvature, that is 30mm, the radius criteria of curvature needs to be revised. These tests results will be so useful to revise and establish a customer cabling system for FTTH.