Hydraulic and ecological changes under drainage gate operations with coupled model SCHISM-CoSiNE in Saemangeum basin, Korea

The drainage gates have been controlled for desalination under normal conditions and flood defense in  Saemangeum basin, Korea. Recently, it became an issue that the gates have been opened not to deteriorate water quality in the lake. It is, thus, necessary to precisely estimate the changes of water quality characteristics, especially DO, phosphate and nitrate, in the lake according to various gate operations. In this study, Semi-implicit Cross-scale Hydroscience Integrated System Model and Carbon, Silicate, Nitrogen Ecosystem model (SCHISM-CoSiNE) which is cable to simulate dynamic exchange such as gate operation conditions was utilized to obtain reliable and reasonable results including hydrodyanamic and environmental variables. For the verification, the measured data at 6 locations in Saemangeum basin was used to compare  incluidng temperatue and salintiy from 2016 and each relative error became small enough to show high accurary. Also, under various scenarios by changing the designated water surface elevation on flood seasons, this model has been applied to present the best designated water surface elevation in terms of both water quality and water supply in the Saemangeum basin. It becomes possbile to show reliable guidance for dynamic operations and environmental changes with this model as requested in near future

One Shot 360-Degree Light Field Capture and Reconstruction with Depth Extraction Based on Optical Flow for Light Field Camera

A system for capturing 360-degree light field information of real-existing object in one shot and then optically reconstructing is proposed. A new depth extraction algorithm for light field cameras is proposed and various camera specifications for practical use of the algorithm are employed for the analysis. With a depth extraction method that was based on optical flow for light field camera, the depth information is extracted more accurately, according to the various specifications of light field camera. For 360-degree shooting, a simple capturing system composed of two mirrors and a light field camera is used. The capturing system has an advantage of being compact and inexpensive. The locations and orientations of the two mirrors are analyzed to optimize 360-degree light field recording. Holographic display is used to optically reconstruct the captured light field information. Experimental and simulation results are presented to support the proposed system and analysis

Ultra-high-definition holography for near-eye display

Holographic near-eye displays (NEDs) have large potential for augmented reality (AR) devices as they modulate the wavefront of light. They can provide observers with comfortable three-dimensional (3D) views with focus-cues, and little optical aberrations since the unwanted phase delay added by optical systems can be compensated by wavefront modulation. With the advent of ultra-high-definition (UHD) spatial light modulator (SLM), a degree of freedom in designing holographic NEDs has been further expanded. Here, we introduce several holographic NEDs using UHD SLM. The holographic NED using an HOE is introduced for the optical see-through display. Besides, the holographic NED with enlarged eye-box using point-source array and eye-tracking method will be presented. Finally, the holographic NED of which optical aberration is compensated by Zernike's polynomial adaptation will be introduced.N

The innovative operation of Imha Reservoir

Imha Reservoir has both a water transfer tunnel connecting Andong Reservoir and a selective withdrawal facility (SWF), which enable the innovative operation of the reservoir. Although these facilities had not been equipped when constructed in 1993, these structural measures were applied afterward as needed for the effective reservoir operation. The tunnel was constructed in 2015 to minimize the spillway discharge of a reservoir during floods by moving water to the other reservoir with free space. The SWF was installed in 2006 to address problems due to the persistent turbidity of Imha Reservoir. The effectiveness of these facilities was demonstrated through the operational cases in October 2019, while some improvements to non-structural measures were derived simultaneously. To prevent damage to the fish ecosystem of Imha reservoir, the tunnel currently was operated in a one-way water movement. However, a two-way water movement should be allowed as designed in the mid to long term. The SWF was operated effectively based on the prediction of the fate and transport of turbid water inside the reservoir using CE-QUAL-W2. Nevertheless, more action procedures on turbid water are required, such as setting clear criteria for the release timing of turbid water, predicting the downstream turbidity variations, etc

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