• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.936-943
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• 1986

The lasing wavelengths and gain characteristics of the array modes of channel-substrate planar(CSP) lasers are presented. The gain values of array modes are determined from the complex coupling coefficients calculated using the fields of neighborig elements of the array. The computations show that for index guided lasers which have fields that are almost real valued, or have only slight phase curvature, the highest order array mode will have preferred oscillation. The inphase or fundamental mode, which produces only one major lobe in the far-field radiation pattern, will have the lowest modal gain of all array modes. Some of the devices discussed have modal gain differences of less than 10 cm**-1 between the highest and fundamental modes. For optical field confinement factors of about 20%, this gain difference corresponds to avtive layer gains of approximately 50**-1.

• PNF and Movement
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• v.7 no.2
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• pp.11-20
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• 2009

Purpose : The purpose of this study is to find out which method is efficient to enhance the flexibility of lower back between PNF(Proprioceptive Neuromuscular Facilitation), static and dynamic stretching. Methods : Subjects were 30 young people between the ages 17 and 19. They were randomly divided into three groups; static group(n=10) performed a static stretching, dynamic group(n=10) performed a dynamic stretching, and PNF group(n=10) performed a PNF stretching. Intervention was provided 5 days per week for 4 weeks. For each case, Trunk flexion forward, trunk flexion backward, trunk left lateral bending, trunk right lateral bending, trunk flexion forward a measuring instrument and tapeline were performed to measured the flexibility of lower back at different times(before starting the exercise, after 4 weeks). Results : The results of the study reveal that the lower back flexibility was a statistically significant difference in all groups(p<.05). There was statistically significant difference between PNF group and static group, PNF group and dynamic group. Conclusion : The finding indicated that PNF may be preferred technique for improving flexibility, and that flexibility training results in an increased consistency of flexibility scores.