Purpose: This study was to analyze refractive error and corneal curvature radius in childhood myopia. Methods: The average age of 9.92 ± 1.08 years Children 50 people(24 males and 26 females) were evaluated for refractive error with an automatic refractometer, Pentacam was used to measure the corneal curvature radius. Results: The mean total spherical diopter was -2.43 ± 1.39D and astigmatism diopter was -0.75 ± 0.66D, horizontal radius of curvature was 7.88 ± 0.23mm, vertical radius of curvature was 7.67 ± 0.23mm, corneal astigmatism -1.18 ± 0.56D, diameter was 11.75 ± 0.47mm, eccentricity was 0.55 ± 0.10. There was no significant difference spherical diopter(t=-0.357, p=0.722), corneal astigmatism (t=1.410, p=0.162), eccentricity(t=0.627, p=0.532) in male and female, astigmatic diopter(t=2.097, p=0.039), horizontal radius of curvature(t=2.397, p=0.018), vertical radius of curvature(t=2.685, p=0.009), diameter(t=2.157, p=0.033) were significantly different. There was no significant difference spherical diopter(t=-0.952, p=0.343), astigmatism diopter(t=1.260, p=0.211), horizontal radius of curvature (t=-0.596, p=0.553) vertical radius of curvature(t=-0.495, p=0.621), corneal astigmatism(t=0.662, p=0.509), diameter (t=-0.411, p=0.682), eccentricity (t=0.080, p=0.937) between in male and female. Conclusions: Male and female were significant different astigmatism diopter, horizontal radius of curvature, vertical radius of curvature, diameter in childhood myopia. There was no significant difference between right eye and left eye.

PURPOSES: The purpose of this study is to estimate the impact of variable message signage (VMS) on traffic safety as a function of road curve radius using statistical methods. METHODS: In order to analyze the impact of VMS installations on traffic safety, travel speed, lateral distance, and geometric data relating to road curvature in each study area was acquired and analyzed for the impact of providing VMS information on driver performance and traffic safety using statistical methods including student t-test, Mann-Whitney test, and the Anderson-Darling test for estimating traffic safety hazard zone in each lane. RESULTS: As a result of analyzing driver performance characteristics before and after providing VMS information, it was determined that by providing VMS information, mean travel speed is deceased and vehicles are driven with increased precision, following the centerline in the first and second lanes. Also the results of analyzing traffic safety impacts of VMS indicate that traffic safety performance factors in the first lane of the Gapyeong section can, on average, increase in the left and right side of the lane by 19.22% and 68.98%, respectively, and in the case of the second lane, safety impacts, on average, can increase in both sides by 100%. For the Hongcheon section, traffic safety impacts in the first lane, on average, can increase along the left and right sides of the lane by 32.31% and 47.18%, and within the second lane, traffic safety can be increased along the left and right side of the lane by 10.97% and -0.01%, respectively. CONCLUSIONS: Based on the results of this study, the impact on traffic safety obtained by providing VMS information for road sections with smaller curve radii is greater than can be obtained for road sections with larger curve radii.

In this study variable radius pulley is proposed, and the proposal should be applied to pulley of CVT. Variable radius pulley consists of two disks and sliding pins. Phase difference of two disks make a change pitch diameter. Therefore change speed is accomplished by changing pitch diameter of pulley. In this paper simulation for slot variation of rotary disk of the variable radius pulley was performed. Softwares for simulation are Pro/Engineer5 and Hypermesh11.0. The results of simulation are appropriate to put to practical use of the variable radius pulley

In this study variable radius pulley is proposed, and the proposal should be applied to pulley of CVT. Variable radius pulley consists of two disks and sliding pins. Phase difference of two disks make a change pitch diameter. Therefore change speed is accomplished by changing pitch diameter of pulley. In this paper analysis of rotating force for slot variation of the rotary disk of variable radius pulley was performed. The results of analysis are appropriate to put to practical use of the variable radius pulley.

In this study, new CVT system adapted for variable radius pulley is proposed to be available for pulley of CVT. Variable radius pulley consists of two disk and sliding pins joined by these disks. On account of phase difference of two disks, sliding pins move to radial direction and pitch diameter is varied. Therefore, change speed is accomplished by varying pitch diameter of pulley. CVT adapted for variable radius pulley is also performed with dynamometer test and axial distance variation. As a experimental result variable radius pulley can be alternative such as bicycle.

목적: 각막 곡률반경을 Pentacam(Oculus inc., Germany)을 이용하여 측정하고 연령과 굴절이상도에 따라 비교·분석하였다. 방법: 본 연구의 취지에 동의하고 안질환이 없으며, 시력교정수술을 시행하지 않은 대학생 군 51명(남성 29명, 여성 22명, 평균나이 22.50±3.31세)과 장노년군 39명(남성 21명, 여성 18명, 평균나이 54.26±6.25세)을 선정하여 타각식 및 자각식 굴절검사를 실시하였고, Pentacam(Oculus inc., Germany)을 이용하여 각막 곡률반경을 측정하였다. 결과: 연령에 따른 각막 전면 곡률반경은 연령이 높을수록 짧았고(p=0.005), 유의한 상관관계가 있었다(r=-0.259, p=0.000). 각막 후면 곡률반경은 연령이 높을수록 짧았고(p=0.043), 유의한 상관관계가 있었다(r=-0.282, p=0.000). 굴절이상에 따른 각막 전면 곡률반경은 근시군이 정시군보다 짧았으나(p=0.016), 상관관계가 없었다. 각막 후면 곡률반경은 근시군이 정시군보다 짧았고(p=0.001), 유의한 상관관계가 있었다(r=-0.258, p=0.001). 결론: 연령과 각막 전·후면 곡률반경은 상관관계가 있었다. 굴절이상과 각막 후면 곡률반경은 상관관계가 있었고, 굴절이상과 각막 전면 곡률반경은 상관관계가 없었다.

본 연구에서는 아스팔트 혼합물의 변형강도시험에서 하중봉의 치수가 변형강도 특성에 미치는 영향을 평가하였다. 이를 위하여 직경(D) 40mm, 하단의 원형 절삭 반경(r)을 10.0mm와 10.5mm로 제작한 두 개의 하중봉으로 아스팔트 혼합물의 변형강도를 측정하고, 반복주행시험을 수행하여 얻어진 소성변형 특성치와 상관성 분석을 하였다. 또한 하중봉의 원형 절삭반경에 따른 골재치수에 어떠한 영향을 미치는지를 확인하기 위하여 통계 분석을 하였다. 변형강도 값과 변동계수는 r=10mm하중봉을 사용한 것이 더 낮은 것으로 나타났다. 또한 r=10mm 하중봉이 변형강도와 소성변형 특성치와 상관성 분석에서도 더 높은 상관성을 보였다. 골재치수와 원형 절삭반경은 변형강도에 영향을 미치는 것으로 나타났으나 두 변수의 교호작용에서는 골재의 크기가 10mm~19mm내에서는 r에 영향을 받지 않는 것으로 나타났다. 따라서 소성변형과의 상관성이 더 우수하며 변동계수도 낮은 것으로 나타난 D=40mm, r=10.0mm의 하중봉을 사용하는 것이 적합할 것으로 판단되었다.

The authors have assembled a sample of 80 W UMa binary systems (42 W-subtype and 38 A-subtype) whose light curves have all been solved by means of the recent W-D code and combined with up-to-date radial velocity solutions. The absolute parameters (masses, radii and luminosities) have been derived (without any constraint on the physical parameters). The main results of this paper are: (1) the mass-luminosity relations for both W&A-subtypes. as well as for all W UMa contact binaries have been shown, (2) the mass-radius relations have been found for both subtypes, (3) some remarks on the evolution status have been presented.