Optical Flow Sensor with Fluorescent-Conjugated Hyperelastic Pillar: A Biomimetic Approach.

Although the Doppler velocity log is widely applied to measure underwater fluid flow, it requires high power and is inappropriate for measuring low flow velocity. This study proposes a fluid flow sensor that utilizes optical flow sensing. The proposed sensor mimics the neuromast of a fish by attaching a phosphor to two pillar structures (A and B) produced using ethylene propylene diene monomer rubber.

Catechol-Fe(III) complexes modified PVDF membrane for hazardous pollutants separation and antifouling properties.

Organic pollutants, such as toluene and xylene, in industrial wastewater negatively impact the environment. Membrane treatment is one of the best methods to reduce impurities in wastewater. Existing membranes that coat the water surface with hydrophilic material only effectively resist the initial fouling, resulting in poor oil and water selectivity.

Suppressing the Shuttle Effect via Polypyrrole-Coated Te Nanotubes for Advanced Na-Te Batteries.

There is a growing demand for research and development of advanced energy storage devices with high energy density utilizing earth-abundant metal anodes such as sodium metal. Tellurium, a member of the chalcogen group, stands out as a promising cathode material due to its remarkable volumetric capacity, comparable to sulfur, and significantly high electrical conductivity. However, critical issues arise from soluble sodium polytellurides, leading to the shuttle effect.

Numerical Study on a Ductile Fracture Model in Pre-Cracked Tension Tests of SUS304L.

The effectiveness of a ductile fracture model in accurately predicting fracture initiation has been demonstrated. In this study, we concentrate on applying the ductile fracture model to pre-cracked structures constructed from SUS304L stainless steel with experimental and numerical analyses. The Swift hardening law was employed to extend the plastic behavior beyond the onset of necking.

Investigating Electrode-Ionomer Interface Phenomena for Electrochemical Energy Applications.

The endeavor to develop high-performance electrochemical energy applications has underscored the growing importance of comprehending the intricate dynamics within an electrode's structure and their influence on overall performance. This review investigates the complexities of electrode-ionomer interactions, which play a critical role in optimizing electrochemical reactions. Our examination encompasses both microscopic and meso/macro scale functions of ionomers at the electrode-ionomer interface, providing a thorough analysis of how these interactions can either enhance or impede surface reactions.

Analysis and derivation of the marine water quality criteria of phenol for Korean seas.

Marine water quality criteria (WQC) have to be determined prior to the derivation of water quality based effluent limitations (WQBELs) for hazardous and noxious substances (HNS) discharged from marine industrial facilities. In this study, we carried out toxicity tests using ten native marine organisms and analyzed international toxicity data and data tested in this study to derive the WQC of phenol for Korean seas. By converting acute values to chronic ones with ACRs (acute-chronic ratios) of each trophic level according to well-verified method, we derived provisional WQC (0.

Boosting oxygen evolution reaction activity with Mo incorporated NiFe-LDH electrocatalyst for efficient water electrolysis.

This work demonstrates a simple and scalable methodology for the binder-free direct growth of Mo-doped NiFe-layered double hydroxides on a nickel substrate via an electrodeposition route at room temperature. A three-dimensional (3D) nanosheet array morphology of the electrocatalyst provides immense electrochemical surface area as well as abundant catalytically active sites. Mo incorporation in the NiFe-LDH plays a crucial role in regulating the catalytic activity of oxygen evolution reaction (OER).

Skywave Detection and Mitigation for the MF R-Mode Continuously Operating Reference Station.

There is an increasing need for an independent terrestrial navigation system, owing to the increasing reliance on global navigation satellite systems (GNSS). The medium-frequency range (MF R-Mode) system is considered a promising alternative; however, the skywave effect caused by ionospheric changes at night can degrade its positioning accuracy. To address this problem, we developed an algorithm to detect and mitigate the skywave effect on MF R-Mode signals.

Nationwide monitoring of cyclic and linear siloxanes in sediment and bivalves from Korean coastal waters: Occurrence, geographical distribution, and bioaccumulation potential.

Contamination of coastal environments by siloxanes is of growing concern. Sediment and bivalves were collected from 50 locations along the Korean coast to assess the geographical distribution, sources, and bioaccumulation potential of siloxanes. Cyclic and linear siloxanes were detectable in all sediment and bivalve samples.

AIS Trajectories Simplification Algorithm Considering Topographic Information.

With the development of maritime technology and equipment, most ships are equipped with an automatic identification system (AIS) to store navigation information. Over time, the size of the data increases, rendering its storage and processing difficult. Hence, it is necessary to transform the AIS data into trajectories, and then simplify the AIS trajectories to remove unnecessary information that is not related to route shape.

Underwater Acoustic Signal Detection Using Calibrated Hidden Markov Model with Multiple Measurements.

It is important to find signals of interest (SOIs) when operating sonar systems. A threshold-based method is generally used for SOI detection. However, it induces a high false alarm rate at a low signal-to-noise ratio.

Fault-Free Protection Level Equation for CLAS PPP-RTK and Experimental Evaluations.

Centimeter level augmentation system (CLAS) of the quasi-zenith satellite system (QZSS) is the first precise point positioning-real time kinematic (PPP-RTK) augmentation system of the global navigation satellite system (GNSS), which is currently providing services for Japan. CLAS broadcasts the state-space representation of correction messages along with integrity messages regarding satellite faults and the quality index of each correction. In other GNSS augmentation systems, such as the space-based augmentation system (SBAS) of GNSS, the quality indices of correction messages are used to generate fault-free protection levels that represent a position bound containing a true user position with a probability of missed detections.

Evaluation of Chloride-Ion Diffusion Characteristics of Wave Power Marine Concrete Structures.

Wave power marine concrete structures generate electrical energy using waves. They are exposed to a multi-deterioration environment because of air and hydrostatic pressure and chloride attack. In this study, the effect of air pressure repeatedly generated by water level change of wave power marine concrete structures on the chloride-ion diffusion of marine concrete was analyzed.

A comparative study of deep learning-based network model and conventional method to assess beach debris standing-stock.

The conventional survey of marine debris standing-stock has various drawbacks such as high cost and inaccuracy because the total amount of debris in the whole beach is inferred using the results of the manual investigation in selected narrow areas. To overcome the disadvantages, an automatic detection method using a deep learning-based network model was developed to detect and quantify the beach debris. The network model developed in this study classified items with a precision of 0.

Development and Performance Evaluation of a Bevameter for Measuring Soil Strength.

The driving performance of an off-road vehicle is closely related to soil strength. A bevameter is used to measure the soil strength, and it usually consists of two independent devices: a pressure-sinkage test device and a shear test device. However, its development and measurement processes have not been standardized; thus, researchers apply it in various fields according to their own discretion.

Localization of multiple ships using a vertical array in shallow water.

The blind deconvolution employs conventional plane-wave beamforming using an array, selects a well-resolved angle of arrival for beam steering to estimate the phase component of an unknown source waveform, and then extracts the Green's function between the source and the array. In this letter, the approach is extended to multiple-ship scenarios in which the multipath arrivals from one ship are masked by other ships, adopting the basic concept of successive interference cancellation. Once individual Green's functions are available, the array invariant method based on the beam-time migration can be subsequently applied to estimate each source range.

Initial environmental risk assessment of hazardous and noxious substances (HNS) spill accidents to mitigate its damages.

In this study, a system was established to perform an initial environmental risk assessment of hazardous and noxious substances (HNS) spill accidents. Initial environmental risk assessment was performed using exposure and hazard assessments. An integrated hydrodynamic and chemical fate model was used to predict HNS concentrations at harbors, taking into account local environmental conditions.

Ray-based blind deconvolution of shipping sources using multiple beams separated by alternating projection.

This article presents a method for improving the performance of the ray-based blind deconvolution (RBD) algorithm, which was first proposed by Sabra, Song, and Dowling [J. Acoust. Soc.

On-demand route discovery in a unicast manner.

While having high bandwidth-efficiency, the ad-hoc on-demand distance vector (AODV) routing protocol suffers from high signaling overhead due to route request (RREQ) messages flooding, especially when the node density and the number of connections are increased. In order to resolve this broadcast storm problem of the AODV in a high node density mobile ad-hoc network, we propose a geographical on-demand route discovery scheme. Assuming a known location of the destination, the RREQ of the proposed routing protocol is propagated in a unicast manner by employing a novel parsing mechanism for possible duplicate RREQs.