Performance evaluation of open-cell caisson breakwater system using finite element method
Recently, coastal city and facilities had many damages by abnormally high waves with climate change. Especially, breakwater systems based on a caisson-type harm damages in Korea because they are located in the outside port. In order to reduce theses damages, new type breakwater systems using interlocking caisson are researched. Generally, caissons of breakwater system were constructed on crushed rock mound. They had a little space of 10–20 cm between each caisson. In this reason, they resist separately under external environmental ocean condition. A resistance mechanism of this method is friction force between caisson and crushed rock. Majority of failure is sliding failure, when it is exposed to more than design load. On the contrary, new type breakwater system as interlocking caissons resists effectively against abnormal wave because they are connected by specific joint method between each caisson. In this study, based on an open-cell caisson which is one of the interlocking concepts, we evaluated the performance of dynamic behavior for breakwater system using finite element analysis such as distribution subgrade reaction force, structural behavior of global system etc. According to analysis result, the open-cell caisson has good performance compare with general caisson type.
Dispersion Characteristics of Wave Forces on Interlocking Caisson Breakwaters by Cross Cables
Damage level of coastal structures has been scaled up according to increase of wave height and duration of the storm due to the abnormal global climate change. So, the design criteria for new breakwaters is being intensified and structural strengthening is also conducted for the existing breakwaters. Recently, interlocking concept has been much attention to enhance the structural stability of the conventional caisson structure designed individually to resist waves. The interlocking caisson breakwater may be survival even if unusual high wave occurs because the maximum wave force may be reduced by phase lags among the wave forces acting on each caisson. In this study, the dispersion characteristics of wave forces using interlocking system that connect the upper part of caisson with cable in the normal direction of breakwater was investigated. A simplified linear model was developed for computational efficiency, in which the foundation and connection cables were modelled as linear springs, and caisson structures were assumed to be rigid. From numerical experiments, it can be found that the higher wave forces are transmitted through the cable as the angle of incident wave is larger, and the larger the stiffness of the interlocking cable makes larger wave dispersion effect.
An automated retinal image quality grading algorithm
This paper introduces an algorithm for the automated assessment of retinal fundus image quality grade. Retinal image quality grading assesses whether the quality of the image is sufficient to allow diagnostic procedures to be applied. Automated quality analysis is an important preprocessing step in algorithmic diagnosis, as it is necessary to ensure that images are sufficiently clear to allow pathologies to be visible. The algorithm is based on standard recommendations for quality analysis by human screeners, examining the clarity of retinal vessels within the macula region. An evaluation against a reference standard data-set is given; it is shown that the algorithm's performance correlates closely with that of clinicians manually grading image quality.