Development of Live Load Distribution Factor Equation for Concrete Multicell Box-Girder Bridges under Vehicle Loading

Abstract The evaluation and design of concrete bridges in large part depend on the transverse distribution characteristics of the live load carried and the service level. The live load distribution for continuous concrete multicell box-girder bridges varies according to bridge configuration, so when designing such bridges, it is important to determine the maximum negative stress at the piers, the midspan positive (tensile) stress and the deflection of the bridge when subjected to live loads. This paper reports an extensive parametric study to determine the maximum stress, deflection, and moment distribution factors for two span multicell box-girder bridges based on a finite element analysis of 120 representative numerical model bridges. Bridge parameters were selected to extend the parameters and ranges of current live load distribution factors defined by AASHTO LRFD specifications. The results indicate that the span length, number of boxes, and the number of lanes all significantly affect the positive (tensile) and the negative (compression) stress distribution factors. A set of equations proposed to describe the behavior of such bridges under AASHTO LRFD live loads yielded results that agreed closely with the numerically derived results for the stress and deflection distribution factors

Determination of Uniaxial Tensile Behavior of Hypodermis in Porcine Skin Based on Rule of Mixtures

In this study, we investigate the mechanical behavior of each skin layer, in terms of the nominal stress-strain curve by uniaxial tensile tests using specimens of porcine skin in two forms: dermis containing epidermis, and all three layers. All tests were performed under cyclic loading at the constant strain rate of 10-3 s-1 at ambient temperature. To measure the precise initial crosssectional areas of each layer, the thickness of each skin layer was quantified by counting the number of pixels on the photo-image using image-processing software. In the tensile test, force-strain curves of the total skin and dermis with epidermis were obtained. Subsequently, a rule of mixtures was applied to determine the nonlinear mechanical properties of the hypodermis layer. In conclusion, we could define the uniaxial tensile behavior of the hypodermis, and additionally predict the weight effect of the dermis and hypodermis layers in the tensile test

Design of Security Platform via Holographic Metasurface with Oblique Helicoidal Liquid Crystals

Metasurfaces (MSs) with sub-wavelength scale of nanostructures have an ability to respond to the properties of incident light (e.g., wavelength, polarization, incident angle) and provide a corresponding programmed optical signal that are predetermined by configuration of nanostructures. Because the configurations of light and nanostructures have the infinite degrees of freedom, therefore, the metasurfaces have been considered as promising security platform that does not allow computational decryption . Here, we propose the simple and versatile design of high security platform via wavelength responsive MS integrated with the layer of oblique helicoidal liquid crystals (LCs). Specifically, we design MS to display holographic images only when target wavelengths of light are exposed. The integrated LC layers are programmed to reflect the target wavelengths under the specific electric field and temperature. Consequently, we demonstrate our security platform to show the encrypted holographic image only when the programmed electric field and temperature are applied. This work was supported by the NRF (2021R1A4A1030944, 2021R1A2C2095010, 2022M3C1A3081312).2

Design of electrically tunable meta-color using liquid crystal modulator

Structural color induced by reflection or transmission of light from micro- or nano-structures has high resolution, environmental protection and high durability against chemical pigments and dyes. Accordingly, metasurface (MS) that is composed of structures with subwavelength-scale has been proposed for promising an optical platform to realize the structural color. Moreover, recent researches of meta-color head to dynamic color modulator with liquid crystals (LCs). In this work, we propose the tunable meta-color via integration of reflective metasurface with LC modulator. The system is consisted of polarization dependence metasurface and polarization modulator LCs. The polarization of the light is controlled by reorientation of LCs with in-plane electrical field. As a result, we realized the full-color active system for RGB colors with grayscale. This work was supported by the Korea National Research Foundation (NRF-2021R1A4A1030944 & 2021R1A2C2095010).2

Tunable meta-color with liquid crystal modulator

High resolution and durability are considered very important factors in display. Structural color induced by reflection or transmission of light from micro- or nano-structures has a potential with high resolution, environmental protection and high durability against chemical pigments and dyes. To realize structural color, metasurface composed of structures with subwavelength-scale has been proposed and called ‘meta-color’. Moreover, these meta-colors are recently combined with liquid crystals (LCs) for dynamic color transition. In this work, we suggest the tunable meta-color via integration of reflective metasurface with LC modulator. The system is consisted of polarization dependence metasurface and polarization modulator LCs. The polarization of the light is controlled by reorientation of LC molecules with in-plane electrical field. As a result, we realized the full-color active system for RGB colors with gray scale. Additionally, the mixing of two colors such as magenta, cyan and yellow is also realized on a pixel. This work was supported by the Korea National Research Foundation (NRF-2021R1A4A1030944 & 2021R1A2C2095010).2

Mid-air Tactile Display Using Indirect Laser Radiation for Contour-Following Stimulation and Assessment of Its Spatial Acuity

1

Fabrication and characterization of zeolitic imidazolate framework-embedded cellulose acetate membranes for osmotically driven membrane process

Abstract Zeolitic imidazolate framework-302 (ZIF-302)-embedded cellulose acetate (CA) membranes for osmotic driven membrane process (ODMPs) were fabricated using the phase inversion method. We investigated the effects of different fractions of ZIF-302 in the CA membrane to understand their influence on ODMPs performance. Osmotic water transport was evaluated using different draw solution concentrations to investigate the effects of ZIF-302 contents on the performance parameters. CA/ZIF-302 membranes showed fouling resistance to sodium alginate by a decreased water flux decline and increased recovery ratio in the pressure retarded osmosis (PRO) mode. Results show that the hydrothermally stable ZIF-302-embedded CA/ZIF-302 composite membrane is expected to be durable in water and alginate-fouling conditions

Understanding carbon nanotube channel formation in the lipid membrane

Carbon nanotubes (CNTs) have been considered a prominent nano-channel in cell membranes because of their prominent ion-conductance and ion-selectivity, offering agents for a biomimetic channel platform. Using a coarse-grained molecular dynamics simulation, we clarify a construction mechanism of vertical CNT nano-channels in a lipid membrane for a long period, which has been difficult to observe in previous CNT-lipid interaction simulations. The result shows that both the lipid coating density and length of CNT affect the suitable fabrication condition for a vertical and stable CNT channel. Also, simulation elucidated that a lipid coating on the surface of the CNT prevents the CNT from burrowing into the lipid membrane and the vertical channel is stabilized by the repulsion force between the lipids in the coating and membrane. Our study provides an essential understanding of how CNTs can form stable and vertical channels in the membrane, which is important for designing new types of artificial channels as biosensors for bio-fluidic studies.11sciescopu

multiplexing molecular spectroscopy via metasurface using plasmonic resonance energy transfer

1

metasurface-driven hyperspectral imaging with plasmonic resonance energy transfer

2