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Increased coastal human intervention and climate change are leading to rapid changes in coastal areas and often causing catastrophic damage to resident populations. The ShorelineS model was introduced, which can explain drastic beach changes were simulated. According to the modeling results, the installation of Gungchon Port caused rapid sedimentation in the south of the port. It was reviewed that the erosion and sedimentation tendency of the beach is changed after the installation breakwater in front of the beach, the erosion in the central part of the beach was somewhat suppressed, and the beach was deposited in the shape of tombolo on the back of the beach. The installation of artificial structures dramatically changes the equilibrium state of the beach and increases the erosion of the direct wave near the structure. The ShorelineS model was the advantage of being able to properly reproduce changes in the coastline by inputting relatively simplified environment and beach information and to quickly predict after installation of artificial structures. The reallity, coastline changes due to various causes, so follow-up studies are needed to predict and effectively respond to this through an advanced model that reflects various conditions.

This study examined the effects of mist generated from NaCl solution on the electrochemical properties of polymer electrolyte membrane fuel cells. Mist-containing Na+ and Cl- ions were generated using a custom-made mist generator. The current density-voltage-power density curves and electrochemical impedance spectroscopy of fuel cells were systematically achieved. Furthermore, long-term stability experiments were carried out using chronoamperometry mode for 20 h with deionized water and NaCl solution. After the chronoamperometry measurement, the regeneration of fuel cells was performed with deionized water. The effects of regeneration methods on the performance of the fuel cell were evaluated. Due to the internally produced H2O, constant voltage regeneration was more effective than open circuit voltage regeneration.

A nonlinear kernel with a bias is proposed here in the convolutional neural network. Negative square of subtraction between input image pixel numbers and the kernel coefficients are convolved to conform new feature map through the convolution layer in convolutional neural network. The operation is nonlinear from the input pixel point of view, as well as from the kernel weight coefficient point of view. Maximum-pooling may follow the feature map, and the results are finally fully connected to the output nodes of the network. While using gradient descent method to train relevant coefficients and biases, the gradient of the square of subtraction term appears in the whole gradient over each kernel coefficient. The new subtraction kernel is applied to two sets of images, and shows better performance than the existing linear convolution kernel. Each coefficient of the nonlinear subtraction kernel has quite image-equivalent meaning on top of pure mathematical number. The subtraction kernel works equally for a given black and white image set and its reversed version or for a given gray image set and its reversed version. This attribute becomes important when patterns are mixed with light color and dark color, or mixed with background color, and still both sides are equally important.

In this study, the effects of flow field types on the electrochemical properties of polymer electrolyte membrane fuel cells (PEMFCs) humidified with NaCl solution are systematically investigated. The parallel flow field and serpentine flow field were used to investigate the PEMFCs. Long-term stability was evaluated for 20 h using chronoamperometry. Fuel cells with both parallel and serpentine flow fields showed a decrease in performance because of the NaCl solution. Interestingly, the PEMFC with the serpentine flow field showed significantly more severe degradation during long-term stability evaluation compared to the fuel cell with the parallel flow field. Electrochemical impedance spectroscopy analysis showed that a significant increase in faradaic resistance caused the degradation of the performance. After long-term stability examinations, regenerations of fuel cells were performed with deionized water at a constant voltage (0.4 V). After the regeneration, the performance of the fuel cells with the serpentine flow field was improved more (52.96%) than the PEMFC with the parallel flow field (1.22%).

Kim, H.; Yoo, H.J., and Lee, J.L., 2021. Nonlinear Kernel Convolutional Neural Network to find median sand particle size. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 1-5. Coconut Creek (Florida), ISSN 0749-0208. Convolutional Neural Network (CNN) has successfully been used in various areas. We focus on predicting various sand particle sizes by applying convolutional neural network with a nonlinear kernel. The nonlinear kernel involves a bias and negative square of subtraction between input image pixel numbers and the kernel coefficients and summation. The convolution layer conform new feature map in Convolutional Neural Network. While using batch gradient descent method to train relevant coefficients and biases, the gradient of the square of subtraction term appears in the whole gradient over each kernel coefficient. The network was examined on regular-sized sands, i.e. 2000, 1000, 500, 250, 125 and 63 micrometer. The network was trained by using various images for each size. It was validated against new images and the absolute error was less than 30 micrometer, respectively, which is satisfactory. The network was applied by using 3 images of sands with size distribution. The results show good validation and satisfactory predictions. In the course of study, several numbers of kernels, kernel sizes, pooling sizes were tried and the optimum architecture for this work was chosen. It is expected that the present network will reduce time and effort in obtaining median sand size in many field projects. The size distribution of sand particles could also be obtained with the present network in the near future.

Yoo, H.J.; Kim, H.; Lee, J.L., and Park, J.Y., 2021. Asymmetry between accretional advance and erosional retreat of shoreline position in on-offshore direction. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 6–10. Coconut Creek (Florida), ISSN 0749-0208. Episodic shoreline retreat often slowed recovery in low frequency periods (weeks or months). The asymmetry between wave energy rise and collapse is closely related to the asymmetry of shoreline advancement and retreat, but the latter is more pronounced due to the different profile adjustment processes. Long-term wave time series data and shoreline time series data were analyzed at Won-pyeong beach located on the east coast of Korea. When waves such as storms come into the beach, the shoreline quickly retreated, and in relatively quiet times, the beach slowly recovered to it's original position. Also, the asymmetry of the shoreline position with respect to time is stronger than that of the wave height. A methodology is proposed here, and the envelope rope curve can be used to predict profile and average shoreline changes in the reference section for erosion steps such as storms.The proposed equation was in good agreement for shoreline asymmetry position, and is satisfactory. Empirical formular are slightly different in the relatively calm period, this is an artificial change formed by external pressure conditions such as artificial nourishment. Several variables were used as correction factors. It`s important for future research to propose standardized correction factors and ranges by applying them at various sites.

Polyethylene/carbon black(PE/CB) composites have been widely used in various application devices such as heating element, temperature sensor and current limiter due to its positive temperature coef...

Surgical models have best shown the relationship between ankle and mid-foot osteoarthritis, although findings regarding the calcaneocuboid joint have varied. To the authors' knowledge, no studies have evaluated the relationship between degenerative changes across the tibiotalar and calcaneocuboid joints. The goal of this study was to determine whether such a relationship exists and which joint degenerates first. A single examiner evaluated 694 tibiotalar and calcaneocuboid joints to determine the presence of osteoarthritis. Multiple linear regression analysis was conducted with a standard P value cutoff ( P Orthopedics. 2016; 39(6):e1112–e1116.]

Classically, it is thought that pain or disability in one leg can stress the contralateral leg, leading to similar symptoms. The mechanism of action for subsequent dysfunction in the healthy limb is thought to involve compensatory changes that are used as a means to reduce stance phase time on the injured limb. This is believed to increase the forces distributed across the healthy limb, ultimately leading to injury. This belief has been challenged, as supportive literature is sparse. The goal of this study was to determine whether an association between tibiotalar (TT) osteoarthritis (OA) in the right vs left lower extremity exists, and whether injury to one lower extremity leads to degeneration in the contralateral lower extremity. The authors evaluated 704 TT joints to determine the presence of OA. A multiple linear regression was performed using a standard P value cutoff ( P P value approaching 0. Findings indicated the absolute value of the difference between right and left TT OA was not zero, and this difference remains significant throughout life. Based on these findings, OA in one ankle does not appear to lead to accelerated OA in the contralateral ankle. [ Orthopedics. 2016; 39(4):e664–e667.]

Cadaveric studies have examined disc degeneration at the L4-L5 and L5-S1 motion segments; however, we are not aware of another study that has examined the relationship between bilateral spondylolysis and its effect on degenerative disc disease at those levels. This may have been overlooked by researchers owing to the majority of spondylolysis occurring at the L5 vertebra. Using osteologic specimens from a collection that included individuals who died in one city in the USA between 1893 and 1938, we asked: (1) do specimens with bilateral spondylolysis (bilateral pars defects) have increased levels of disc degeneration, at their respective motion segments, when compared with matched controls without spondylolysis, and (2) is the finding of a bilateral pars defect associated with more severe arthritis at L4-L5 than at L5-S1? An observational study was performed on 665 skeletal lumbar spines from the Hamann-Todd Osteologic Collection at the Cleveland Museum of Natural History (Cleveland, OH, USA). The specimens included 534 males and 131 females ranging from 17 to 87 years old, with a nearly bell-shaped distribution of ages for males and a larger proportion of younger ages in the female specimens. Of those with spondylolysis, 81 had a defect at L5 and 14 had a defect at L4. The gross specimens were examined subjectively for evidence of arthrosis. At the time of examination, specific attention was not paid to the coexisting presence or absence of spondylolysis nor was the examiner blinded to the age of the specimens. Disc degeneration was measured by the classification of Eubanks et al., a modified version of the Kettler and Wilke classification. Linear regression was performed to derive a formula that would predict the amount of disc degeneration at L4-L5 and L5-S1 for the normal control population given a specimen’s age, sex, and race. We then used this formula to evaluate the difference in disc degeneration at the corresponding level of the pars defect that is greater than the predicted amount for a control without spondylolysis. This allowed us to conclude that any significant differences found between the L4-L5 and L5-S1 cohorts were attributable to factors not simply inherent to their functional position in the spine of an individual without a bilateral pars defect. L4 spondylolysis and L5 spondylolysis showed greater amounts of degeneration compared with that of matched controls (L4 controls: mean = 1.52, SD = 0.74; L4 spondylolysis: mean = 3.21, SD = 0.87; p < 0.001; L5 controls: mean = 0.97, SD = 0.48; L5 spondylolysis: mean = 2.06, SD = 0.98; p < 0.001). When we controlled for the expected amount of degenerative disc disease at each level in controls, the observed degeneration was more severe at L4-L5 than at L5-S1 (p = 0.008, R-squared = 18.6). L4-L5 and L5-S1 bilateral spondylolysis groups had increased presence of degenerative disc disease compared with those without bilateral spondylolysis. For the same degree of spondylolysis, the observed amount of disc degeneration was greater at the L4-5 motion segment compared with L5-S1. Although not as common as the spondylolysis at L5-S1, we believe that our findings support that patients with L4-L5 spondylolysis can expect a greater degree of degenerative disc disease and increasing clinical symptoms. Multiple factors in the sacropelvic geometry of an individual, facet morphologic features at L4-L5, and the absence of the iliolumbar ligament at this level are possible contributing factors to the findings of this study.