305 results match your criteria: "Seoul National University of Science and Technology (SeoulTech); sunkkim@seoultech.ac.kr.[Affiliation]"

Aqueous two-phase systems (ATPSs) have primarily been developed in the form of emulsions to enhance their utilization in green and biocompatible applications. However, numerous challenges have arisen in forming stable and processable water-in-water (W/W) emulsion systems, as well as in fine-tuning the interconnectivity of their internal structure, which can significantly impact their performance. To effectively address these challenges, we elucidate, for the first time, the root cause of the poor stability of W/W emulsions.

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As proximity-aware services among devices such as sensors, IoT devices, and user equipment are expected to facilitate a wide range of new applications in the beyond 5G and 6G era, managing heterogeneous environments with diverse node capabilities becomes essential. This paper analytically models and characterizes the performance of heterogeneous random access-based wireless mutual broadcast (RA-WMB) with distinct transmit (Tx) power levels, leveraging a marked Poisson point process to account for nodes' various Tx power. In particular, this study enables the performance of RA-WMB with heterogeneous Tx power to be represented in terms of the performance of RA-WMB with a common Tx power by deriving an equivalent Tx power based on the probability distribution of heterogeneous Tx power and the path loss exponent.

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Article Synopsis
  • The study addresses the challenges in performing multi-omics analysis on single samples in zebrafish toxicology, presenting a new method for simultaneous metabolomics and lipidomics analysis of zebrafish embryos exposed to PFOS.
  • Using methyl tert-butyl ether (MTBE) for extraction, the researchers found that metabolite and lipid profiles were comparable to those from other solvents, demonstrating MTBE's effectiveness for multi-omics analysis while minimizing the number of embryos needed.
  • The findings reveal new insights into the neurotoxicity mechanisms of PFOS, highlighting alterations in behavior and the involvement of energy metabolism and sphingolipids, thus enhancing the understanding of toxic chemical effects on biomolecules.
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Next-generation 6G communication holds the potential to revolutionize data transfer, enabling the realization of eXtended Reality (XR) with enhanced sensory experiences. To achieve this, advanced components such as high-performance intensity/phase modulators, waveguides, multiplexers, splitters, combiners, and filters operating in terahertz (THz) regime, specifically within the frequency range of 0.1-1 THz, are essential.

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The surge in global plastic production, reaching 400.3 million tons in 2022, has exacerbated environmental pollution, with only 11% of plastic being recycled. Catalytic recycling, particularly through hydrogenolysis and hydrocracking, offers a promising avenue for upcycling polyolefin plastic, comprising 55% of global plastic waste.

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Gelatin-alginate hydrogel for near-field electrospinning assisted 3D and 4-axis bioprinting.

Carbohydr Polym

January 2025

Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea; Convergence Institute of Biomedical Engineering and Biomaterials, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea. Electronic address:

A near-field electrospinnable and three-dimensional (3D) bioprintable gelatin-alginate hydrogel was synthesized by controlling a moderate amount of alginate and a limited amount of crosslinker, tannic acid. This cytocompatible gelatin-alginate tough hydrogel exhibited excellent shape fidelity, a self-standing height exceeding 20 mm, and the capability for multilayer and four-axis 3D printing of complex scaffold shapes. The control of gel strength and rheology enables this hydrogel for successful stretching extrusion under an electric field in near-field electrospinning-induced 3D printing and four-axis printing.

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Article Synopsis
  • A new viscoelastic flow focusing device is designed to effectively concentrate submicron-sized particles, including bacteria, in the center of a microchannel without external forces by adjusting factors like channel length and fluid composition.
  • The device uses a long polydimethylsiloxane (PDMS) channel, allowing for high flow rates and successful focusing of particles as small as 100 nm with impressive efficiency.
  • Demonstrations with polystyrene beads and E. coli bacteria show the device’s potential for biological and clinical applications, such as pathogen detection and antibiotic response evaluations in single tests.
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Indoor fungal contamination poses significant challenges to human health and indoor air quality. This study addresses an effective approach using mass spectrometry and machine learning to identify microbial volatile organic compounds (MVOCs) originated from indoor fungi. Three common indoor fungi, including Penicillium Chrysogenum, Cladosporium cladosporioides, and Aspergillus niger, were cultivated on various substrates, namely potato dextrose agar, wallpaper, and silicone.

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Simultaneous processing of both handheld biomixing and biowriting of kombucha cultured pre-crosslinked nanocellulose bioink for regeneration of irregular and multi-layered tissue defects.

Int J Biol Macromol

December 2024

Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea; Convergence Institute of Biomedical Engineering and Biomaterials, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea. Electronic address:

The nanocellulosic pellicle derived from the symbiotic culture of bacteria and yeast (Kombucha SCOBY) is an important biomaterial for 3D bioprinting in tissue engineering. However, this nanocellulosic hydrogel has a highly entangled gel network. This needs to be partially modified to improve its processability and extrusion ability for its applications in the 3D bioprinting area.

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The Water Quality Index (WQI) is widely used as a classification indicator and essential parameter for water resources management projects. WQI combines several physical and chemical parameters into a single metric to measure the status of Water Quality. This study explores the application of five soft computing techniques, including Gene Expression Programming, Gaussian Process, Reduced Error Pruning Tree (REPt), Artificial Neural Network with FireFly (ANN-FFA), and combinations of Reduced Error Pruning Tree with bagging.

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This study investigates the hydrogen embrittlement behavior of API X70 linepipe steel. The microstructure was primarily composed of a dislocation-rich bainitic microstructure and polygonal ferrite. Slow strain-rate tests (SSRTs) were performed under both ex situ and in situ electrochemical hydrogen charging conditions to examine the difference between hydrogen diffusion and trapping behaviors.

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Natural biomaterials for sustainable flexible neuromorphic devices.

Biomaterials

March 2025

Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea; Institute of Engineering Research, Research Institute of Advanced Materials, Soft Foundry, SN Display Co. Ltd., Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, 08826, Republic of Korea. Electronic address:

Neuromorphic electronics use neural models in hardware to emulate brain-like behavior, and provide power-efficient, extremely compact, and massively-parallel processing, so they are ideal candidates for next-generation information-processing units. However, traditional rigid neuromorphic devices are limited by their unavoidable mechanical and geometrical mismatch with human tissues or organs. At the same time, the rapid development of these electronic devices has generated a large amount of electronic waste, thereby causing severe ecological problems.

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This study investigated the impact of water-soluble substances on Ostwald ripening in emulsions stabilized by surfactants with different head groups (Brij S20 and Tween 60). Adding ≥20% (w/w) corn oil to the oil phase effectively inhibited Ostwald ripening of n-decane emulsions due to compositional ripening. The presence of glucose, maltose, or glycerol in the aqueous phase of the emulsions decreased the Ostwald ripening rate, regardless of emulsifier type.

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Although polyethylene terephthalate (PET) fibers are a representative form of plastic pollutants, studies on their toxicity are currently limited compared to other plastic types. Moreover, the effect of natural organic matter (NOM) on their toxicity has not been investigated. In this study, female and male adult zebrafish were exposed to synthesized PET fibers at concentrations of 0.

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The purification of indoor air is a crucial application of photocatalysis, emphasizing the urgent need for more efficient photocatalytic systems. While photocatalytic oxidation of volatile organic compounds (VOCs) has been extensively studied in the liquid phase, effective removal of VOCs in the gaseous state in indoor air remains a significant challenge. This study focuses on the continuous gas-phase oxidation of gaseous acetaldehyde using ZnO and different weight percentage of Fe-grafted ZnO catalysts under light irradiation.

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Despite the keen interest in potentially using the metal-organic framework (MOF) in advanced oxidation processes (AOPs), their application for environmental abatement and the corresponding degradation mechanisms have remained largely elusive. This study explores the use of cobalt-based MOF (CoMOF) for peroxymonosulfate (PMS) activation to remove tetracycline (TC) from water resources. Under optimal conditions, the given catalytic system could achieve a TC removal of 83.

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This study focuses on predicting the prognosis of acute ischemic stroke patients with focal neurologic symptoms using a combination of diffusion-weighted magnetic resonance imaging (DWI) and clinical information. The primary outcome is a poor functional outcome defined by a modified Rankin Scale (mRS) score of 3-6 after 3 months of stroke. Employing nnUnet for DWI lesion segmentation, the study utilizes both multi-task and multi-modality methodologies, integrating DWI and clinical data for prognosis prediction.

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Very fast, high-resolution aggregation 3D detection CAM to quickly and accurately find facial fracture areas.

Comput Methods Programs Biomed

November 2024

ZIOVISION Co., Ltd., Chuncheon, 24341, Kangwon, Republic of Korea; Department of Computer Science and Engineering, Seoul National University of Science and Technology, Seoul, 01811, Republic of Korea. Electronic address:

Background And Objective: The incidence of facial fractures is on the rise globally, yet limited studies are addressing the diverse forms of facial fractures present in 3D images. In particular, due to the nature of the facial fracture, the direction in which the bone fractures vary, and there is no clear outline, it is difficult to determine the exact location of the fracture in 2D images. Thus, 3D image analysis is required to find the exact fracture area, but it needs heavy computational complexity and expensive pixel-wise labeling for supervised learning.

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StochCA: A novel approach for exploiting pretrained models with cross-attention.

Neural Netw

December 2024

Department of Data Science, Seoul National University of Science and Technology, Seoul 01811, South Korea; Department of Industrial Engineering, Seoul National University of Science and Technology, Seoul 01811, South Korea; Research Center for Electrical and Information Technology, Seoul National University of Science and Technology, Seoul 01811, South Korea. Electronic address:

Utilizing large-scale pretrained models is a well-known strategy to enhance performance on various target tasks. It is typically achieved through fine-tuning pretrained models on target tasks. However, naï ve fine-tuning may not fully leverage knowledge embedded in pretrained models.

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Observed flash drought to persist in future over southern Africa.

Sci Total Environ

November 2024

Faculty of Civil Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, South Korea. Electronic address:

Southern Africa has experienced multiple occurrences of drought episodes, which is projected to persist in the future, considering all climate scenarios. Despite the documented change in a meteorological, agricultural, and hydrological drought situation in the region, few studies are yet to explore the changes in flash drought (hereafter; FD), which is characterized by a rapid reduction in root-zone soil moisture and more substantial intensification in few days to weeks. Here, we analyze the observed FD and related underlying drivers during the past 34 years.

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Text classification plays a major role in research such as sentiment analysis, opinion mining, and customer feedback analysis. Text classification using hypergraph algorithms is effective in capturing the intricate relationships between words and phrases in documents. The method entails text preprocessing, keyword extraction, feature selection, text classification, and performance metric evaluation.

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Numerous studies on neuromorphic computing systems and their associated synaptic devices have been reported for the efficient processing of complex data. Among them, organic electrochemical transistors (OECTs) have attracted considerable attention owing to their advantages such as low cost, high scalability, and facile electrical modulation. However, the requirement of supplementary processing for ionic transport control to actualize or enhance synaptic attributes necessitates a compromise between their inherent benefits.

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Article Synopsis
  • Stratified films are high-performance materials, but traditional layer-by-layer fabrication methods are time-consuming and prone to defects.
  • Recent self-stratification methods using drying colloidal mixtures have limitations due to strict operating conditions and heterogeneous layers.
  • This study introduces an active interfacial stratification process using nanoparticles with different interfacial activities, enabling the creation of uniform stratified nanoparticle films that can be applied in drug delivery and flexible electronics.
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Comparative evaluation of the antihyperglycemic effects of three extracts of sea mustard (Undaria pinnatifida): In vitro and in vivo studies.

Food Res Int

August 2024

Department of Food Science and Biotechnology, Seoul National University of Science and Technology, 232, Gongneung-ro, Nowon-gu, Seoul 01811, Republic of Korea. Electronic address:

Undaria pinnatifida (UP) contains multiple bioactive substances, such as polyphenols, polysaccharides, and amino acids, which are associated with various biological properties. This study aimed to evaluate the antihyperglycemic effects of three extracts obtained from UP. UP was extracted under three different conditions: a low-temperature water extract at 50 °C (UPLW), a high-temperature water extract at 90 °C (UPHW), and a 70 % ethanol extract (UPE).

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