Kumoh National Institute of Technology
  • Gumi, Gyeongsangbuk-do, South Korea
Recent publications
text. The sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline conditions continue to pose a significant challenge for the practical implementation of anion‐exchange membrane fuel cells. Developing single‐atom catalysts can accelerate the pace of new HOR catalyst discovery for highly cost‐effective and active HOR performance. However, single‐atom catalysts (SACs) for the alkaline HOR have rarely been reported, and fundamental studies on the rational design of SACs are still required. Herein, we report the design of Ru SAC supported on the ordered mesoporous tungsten carbide (Ru SA/WC 1‐x ) via in situ high‐temperature annealing strategy. The resulting Ru SA/WC 1‐x catalyst exhibits remarkably enhanced HOR performance in alkaline media, a level of activity that could not be achieved with carbon‐supported Ru SAC. Electrochemical results and density functional theory demonstrate that promoting the hydroxyl adsorption on Ru SA/WC 1‐x interfaces, which is derived from the low potential of zero charge of WC 1‐x support, has significant effect on enhancing the HOR performance of SACs. This enhancement leads to 5.8 and 60.1 times higher Ru mass activity of Ru SA/WC 1‐x than Ru nanoparticles on carbon and Ru SA on N‐doped carbon, respectively. This work provides new insights into the design of highly active SACs for alkaline HOR. This article is protected by copyright. All rights reserved
Synthesis of new quinoline derivatives based on mono-functional polybenzoxazines for oil-water separation, anti-corrosion and antibacterial applications, Composite Interfaces, ABSTRACT In the present work, novel and effective quinoline-based polybenzox-azines coatings were prepared on cotton fabrics and mild steels to improve the hydrophobic properties and corrosion resistance, respectively. For this purpose, four quinoline containing mono-oxazine-based benzoxazines were synthesized using 8-hydroxyquinoline (Q), and various monoamines, such as: butylamine (ba), hexylamine (ha), octy-lamine (oa) and aniline (a). The molecular structure of the benzoxazine monomers was verified by 1 H-NMR and FTIR spectroscopy. The effect of the aliphatic and aromatic functional groups of the benzoxazines on oxazine ring-opening curing was investigated, and the influence of their corresponding materials on thermal and morphological properties was also elucidated. These quinoline-based monomers have been successfully coated onto the surface: i) cotton fabrics to be used as a water-oil separation method; and ii) mild steel as inhibitor of the corrosion. In this sense, cotton fabric coatings exhibited highly hydro-phobic properties (contact angle from 124° to 139°), and subsequently the water oil-separation efficiency was measured to the material that presented the highest contact angle (Poly Q-oa), obtaining a 91% separation efficiency. For benzoxazines coatings on mild steel, impedance tests have indicated that these polymers are corrosion inhibitor effectives. Finally, the antibacterial properties of the quinoline based benzoxazines was also analysed, indicating good antibacterial ARTICLE HISTORY resistance owing to the existence of long alkyl chains in their respective molecular structure. According to the results obtained from numerous analyses, the quinolone-based polybenzoxazines can be considered as successful materials for applications such as corrosion resistance, oil-water separation, marine coating and microelectronics insulation.
The accelerated industrial transformation has witnessed the supervisory control and data acquisition (SCADA) transit from monolithic to the Internet of Things (IoT-SCADA). The development also transformed conventional specialized serial-based to transmission control protocol/internet protocol reliant standard communication protocols, such as IEC-60870-5-104 (IEC-104), thereby increasing vulnerability to attacks and intrusions. Maintaining the reliability and availability of IoT-SCADA demands versatile and robust monitoring of network traffic. This study proposes a monitoring technique to detect and characterize the IEC-104 IoT-SCADA network traffic. The proposed trees bootstrap aggregation monitoring technique of GridSearchCV() hyperparameter tuning of 11 n-estimator, 20 max-depth, and 5-k cross-validation achieved early detection and characterization. Experimental results demonstrate its sensitivity and precision in detecting and classifying various network traffic and application types at a minimal execution time while reducing false alarm rates, which is vital for mitigating intrusions in heterogeneous IoT-SCADA networks.
Polypropylene (PP) blended with rubber particles has been recognized for significantly increasing impact resistance, which is increasingly demanded in industries such as electric vehicles and consumer electronics. However, a comprehensive understanding of the toughening mechanisms underlying these lightweight impact-resistant materials is imperative for future research. This article provides a detailed review of the ductile-to-brittle (DB) transition behavior and the improvements in impact resistance observed in rubber-toughened PP blends. Firstly, the fracture behavior of homogeneous PP is summarized across different strain rates and temperatures, including the DB transition and yielding and crazing criteria. Furthermore, the influence of notches and defects on the DB transition is discussed extensively. Subsequently, the article examines the theoretical and practical aspects of the toughening mechanisms facilitated by the rubber phase in PP-rubber blends. The percolation model is used to investigate the inter-distance criterion between neighboring rubber particles and the impact of particle size and content on toughening behavior. The primary objective of this article is to enhance the understanding of the toughening behavior exhibited by PP and rubber blends. Additionally, this study aims to provide valuable insights for developing advanced lightweight materials using PP-based blends for various industrial applications.
Graphene oxide membrane (GOM) shows promise as an alternative for proton exchange membrane fuel cells (PEMFCs) due to its hydrophilic nature, which promotes attractive proton conductivity under wet conditions. However, GOM-based fuel cells (GOMFCs) exhibit lower maximum power density than Nafion (R) due to issues such as fuel crossover, membrane degradation, and loss of oxygen surface functional groups. In this study, amorphous double-layer Ni 64 Zr 36 /Ni 36 Zr 64 thin films demonstrate superior hydrogen permeability compared to double-layer Ni 64 Zr 36 /Ni 36 Zr 64 (crystalline), single-layer Ni 64 Zr 36 (amorphous/crystalline), and Pd 77 Ag 23 thin films at low temperatures, particularly near room temperature. Two types of amorphous and crystalline Ni−Zr metal films, with double or single layers, were characterized, and their hydrogen purification performance was reported. For hydrogen membrane fuel cell (HMFC) applications, a silanization process was employed by reacting a 50 wt % (5 mg/mL) solution of graphene oxide (GO) with an equimolar ratio of (3-mercaptopropyl)trimethoxysilane [MPTS, HS(CH 2) 3 Si(OCH 3) 3 ] (0.790 g/mL) to form a MPTS-modified GO composite electrolyte (MGC-50). In the HMFCs, double-layer membranes composed of GOM or MGC-50 and the hydrogen-permeable Ni−Zr thin film developed in this study were investigated as an electrolyte membrane. A hydrogen-permeable metal thin film, around 40 nm in thickness, was deposited onto GOM or MGC-50 using a Pd or Ni−Zr target via DC magnetron sputtering, resulting in a double-layer graphene oxide-hydrogen membrane (GOHM) electrolyte. The fuel cell performance of the fabricated Pd-and Ni−Zr-based GOHMFCs was compared with conventional PEMFCs.
Recently, there has been considerable interest in 2D Janus transition metal dichalcogenides owing to their unique structure that exhibits broken mirror symmetry along the out‐of‐plane direction, which offers fascinating properties that are applicable in various fields. This study investigates the issue of process instability in Janus MoSSe, which is mainly caused by its nonzero net dipole moments. It systematically investigates whether the built‐in dipole moments in Janus MoSSe make it susceptible to delamination by most polar solvents and increase its vulnerability to intense moisture adsorption, which leads to the deterioration of its semiconducting properties. To address these issues, as an example of device applications, field‐effect transistors (FETs) based on a van der Waals heterostructure are devised, where the bottom h‐BN (top h‐BN) insulating material is employed to prevent delamination (adsorption of moisture). The fabricated FETs exhibit improved electron mobility and excellent stability under ambient conditions.
Aqueous rechargeable static zinc–iodine (Zn–I2) batteries are regarded as competitive candidates for next-generation energy storage devices owing to their safety and high energy density. However, their inherent limitations such as the shuttle effect, sluggish electrochemical kinetics, and the poor electrical conductivity of iodine have been challenging to mitigate when using methods that confer polarity to the surface of the carbon host through nitrogen doping. Moreover, the considerable prevalence of inactive pyridinic N sites significantly impedes the establishment of approaches to overcome issues associated with redox kinetics and iodine utilization. Herein, single Ni atoms were incorporated into an electrochemically inactive N-doped carbon matrix by carbonizing a zeolitic imidazolate framework and then thermally activating the Ni ions adsorbed onto the carbonized product. The single Ni atoms modulated the electronic structure of the surrounding N-doped carbon matrix, thereby improving its ability to adsorb polyiodides and exhibit bifunctional catalytic activity for iodine reduction and oxidation reactions. Consequently, the assembled Zn–I2 battery delivered an outstanding rate performance (193 mA h g⁻¹ at a current density of 6 A g⁻¹) and ultralong cyclability (10 000 cycles at a current density of 4 A g⁻¹). Overall, this study illuminates the merits of using single-atom catalysts to revitalize inactive N pyridinic sites, thereby providing a promising direction for further advancement of Zn–I2 batteries.
Since Grover devised a quantum algorithm for unstructured search, generalization of the algorithm to structured data sets represented by graphs has been an important research topic. The introduction of absorbing marked vertices provided a breakthrough for this problem, and recently it was proved that a quantum walk search algorithm replacing the marked vertices by partially absorbing vertices can find a marked vertex in any reversible Markov chain with any number of marked vertices. However, in contrast, the proof based on the quantum fast-forwarding technique gives little intuition about the underlying mechanism, while the spectral analysis of Grover’s algorithm leads to understanding of the searching mechanism as a rotation in a two-dimensional space. For a spectral approach to the quantum search on Markov chains, we consider as a nontrivial example the complete bipartite graph consisting of two sets \(X_1\) and \(X_2\) and the marked vertices being only in \(X_2\). By analytically determining the spectral information of the quantum walk, we demonstrate that the quantum algorithm shows quadratic speed-up compared to the corresponding classical search method. And we find that the quantum search is described in terms of a two-state model for that case.
Chronic Kidney Disease (CKD) which involves gradual loss of kidney function is characterized by low levels of a glycoprotein called Erythropoietin (EPO) that leads to red blood cell deficiency and anemia. Recombinant human EPO (rhEPO) injections that are administered intravenously or subcutaneously is the current gold standard for treating CKD. The rhEPO injections have very short half-lives and thus demands frequent administration with a risk of high endogenous EPO levels leading to severe side effects that could prove fatal. To this effect, this work provides a novel approach of using lamellar inorganic solids with a brucite-like structure for controlling the release of protein therapeutics such as rhEPO in injectable hydrogels. The nanoengineered injectable system was formulated by incorporating two-dimensional layered double hydroxide (LDH) clay materials with a high surface area into alginate hydrogels for sustained delivery. The inclusion of LDH in the hydrogel network not only improved the mechanical properties of the hydrogels (5–30 times that of alginate hydrogel) but also exhibited a high binding affinity to proteins without altering their bioactivity and conformation. Furthermore, the nanoengineered injectable hydrogels (INHs) demonstrated quick gelation, injectability, and excellent adhesion properties on human skin. The in vitro release test of EPO from conventional alginate hydrogels (Alg-Gel) showed 86% EPO release within 108 h while INHs showed greater control over the initial burst and released only 24% of EPO in the same incubation time. INH-based ink was successfully used for 3D printing, resulting in scaffolds with good shape fidelity and stability in cell culture media. Controlled release of EPO from INHs facilitated superior angiogenic potential in ovo (chick chorioallantoic membrane) compared to Alg-Gel. When subcutaneously implanted in albino mice, the INHs formed a stable gel in vivo without inducing any adverse effects. The results suggest that the proposed INHs in this study can be utilized as a minimally invasive injectable platform or as 3D printed patches for the delivery of protein therapeutics to facilitate tissue regeneration. Supplementary Information The online version contains supplementary material available at 10.1186/s12951-023-02160-2.
This study aims to investigate the effectiveness of para-aramid fiber sheet in enhancing the flexural performance of reinforced concrete (RC) beams made with Environmental-Friendly Recycled Coarse Aggregates. The experimental program examines the effect of substitution ratio of recycled aggregates (0%, 30%, and 50%), type of para-aramid fiber sheet (KN 206 RFL and KN AA070-RFL), and the method of fiber sheet attachment (bottom and bottom-side). The test results show that the ultimate load-carrying capacity of RC beams reinforced with para-aramid fiber sheet attached to the bottom and side parts increased by 23.9% compared to the unreinforced specimens. The main findings of the study include the identification of the BU-type attachment method as the most effective method for enhancing the flexural performance of reinforced concrete beams. The comparison of the experimental results with analytical predictions showed that the nominal flexural strength obtained from the experimental study was lower than the analytical predictions, but the ductile capacity of the specimens indicated the effectiveness of para-aramid fiber sheet reinforcement in EFRCA RC beams for flexural strength. The study highlights the potential of using para-aramid fiber sheet in improving the flexural behavior of RC beams made with recycled aggregates, offering a sustainable solution for the construction industry.
Artificial intelligence (AI) is transforming services by providing personalized solutions, enhancing customer experience, and reducing operational costs. To tackle the challenges posed by the extensive and diverse literature on AI services, a comprehensive review was conducted using text mining techniques on journal articles. Twelve key research topics were identified, and the enabler–interface–business framework was developed. In addition, a value creation mechanism for AI services consisting of 6Cs (i.e., connection, collection, and computation, communication, control, and co-creation) was proposed. The study provides a complete overview of AI services, facilitating academic discussion and industrial transformation.
Inflammatory M1 macrophages create a hostile environment that impedes wound healing. Phosphoserine (PS) is a naturally occurring immunosuppressive molecule capable of polarizing macrophages from an inflammatory phenotype (M1) to an anti-inflammatory phenotype (M2). In this study, we designed, fabricated, and characterized PS-immobilized chitosan hydrogels as potential wound dressing materials. A PS group precursor was synthesized via a phosphoramidite reaction and subsequently immobilized onto the chitosan chain through an EDC/N-hydroxysuccinimide reaction using a crosslink moiety HPA. The PS/HPA-conjugated chitosan (CS-PS) was successfully synthesized by deprotecting the PS group in HCl. In addition, the hydrogels were prepared by the HRP/H2O2 enzyme-catalyzed reaction with different PS group contents (0, 7.27, 44.28 and 56.88 μmol g-1). The immobilization of the PS group improved the hydrophilicity of the hydrogels. Interestingly, CS-PS hydrogel treatment upregulated both pro-inflammatory and anti-inflammatory cytokines. This treatment also resulted in alterations in the macrophage cell morphology from the M1 to M2 phenotype. The CS-PS hydrogel significantly accelerated diabetic wound healing. Overall, this study provides insights into the potential of PS-immobilized hydrogel materials for improved inflammatory disease therapy.
The release of wastewater containing oily contaminants into water bodies and soils severely threatens the environment and human health. Although several conventional techniques are used in treating oil/water mixtures and emulsions, these methods are often expensive, time-consuming, and inefficient. Porous membranes or sponges are widely used in filtration or absorption, but their use is limited by their low separation efficiencies and secondary contamination. Recently, a novel technology that is designed to selectively separate oil from oil/water mixtures or emulsions by using materials with special wetting surfaces was developed. Superwetting surfaces may be used to selectively separate oils from emulsions. This approach enables the use of materials with relatively large pores, resulting in high throughput properties and efficiencies. In this study, a facile method is proposed for use in preparing a superhydrophobic–superoleophilic felt fabric for utilization in separating oil/water mixtures and emulsions. By hydrolyzing aluminum nitride nanopowders, the desired micro-/nanostructures may be successfully fabricated and firmly attached to a fabric surface without using a binder resin. This results in various materials with special wetting properties, regardless of their sizes and shapes and the successful separation of oil and water from oil/water mixtures and emulsions in harsh environments. This approach exhibits promise as a low-cost, scalable, and efficient method of separating oily wastewater, with the potential for use in wider industrial applications.
In the present work, multi-walled carbon nanotubes (MWCNT) were anchored with the assistance of vinyl ester resin (VE) on the carbon fiber surfaces of conventional carbon fabrics (CCF) and semi-spread carbon fabrics (SSCF) having different areal density, ply thickness, and crimp number, respectively. Here, MWCNT anchoring means that MWCNT were physically attached on the individual carbon fiber surfaces of each fabric by coating with dilute VE and then by thermally curing it. The MWCNT anchoring effect on the interlaminar shear strength (ILSS) of CCF/VE and SSCF/VE composites was investigated. MWCNT were also simply applied (without physical attachment) to the carbon fiber surfaces of CCF and SSCF for comparison, respectively. It was found that SSCF/VE composites exhibited the ILSS higher than CCF/VE composites, regardless of simple-applying or anchoring of MWCNT, increasing the ILSS with the MWCNT concentration. It was noted that MWCNT anchoring was effective to improve not only the interlaminar adhesion but also the interfacial bonding between the carbon fiber and the matrix due to the formation of MWCNT bridges between the individual carbon fibers of SSCF, indicating that the MWCNT anchoring effect was more pronounced with SSCF than with CCF. The result of the interlaminar property was well supported by the fiber and composite fracture topography.
In this paper, we investigate the structural, microstructural, dielectric, and energy storage properties of Nd and Mn co-doped Ba0.7Sr0.3TiO3 [(Ba0.7Sr0.3)1−xNdxTi1−yMnyO3 (BSNTM) ceramics (x = 0, 0.005, and y = 0, 0.0025, 0.005, and 0.01)] via a defect dipole engineering method. The complex defect dipoles (𝑀𝑛”𝑇𝑖−𝑉∙∙𝑂)∙ and (𝑀𝑛”𝑇𝑖−𝑉∙∙𝑂) between acceptor ions and oxygen vacancies capture electrons, enhancing the breakdown electric field and energy storage performances. XRD, Raman, spectroscopy, XPS, and microscopic investigations of BSNTM ceramics revealed the formation of a tetragonal phase, oxygen vacancies, and a reduction in grain size with Mn dopant. The BSNTM ceramics with x = 0.005 and y = 0 exhibit a relative dielectric constant of 2058 and a loss tangent of 0.026 at 1 kHz. These values gradually decreased to 1876 and 0.019 for x = 0.005 and y = 0.01 due to the Mn2+ ions at the Ti4+- site, which facilitates the formation of oxygen vacancies, and prevents a decrease in Ti4+. In addition, the defect dipoles act as a driving force for depolarization to tailor the domain formation energy and domain wall energy, which provides a high difference between the maximum polarization of Pmax and remnant polarization of Pr (ΔP = 10.39 µC/cm2). Moreover, the complex defect dipoles with optimum oxygen vacancies in BSNTM ceramics can provide not only a high ΔP but also reduce grain size, which together improve the breakdown strength from 60.4 to 110.6 kV/cm, giving rise to a high energy storage density of 0.41 J/cm3 and high efficiency of 84.6% for x = 0.005 and y = 0.01. These findings demonstrate that defect dipole engineering is an effective method to enhance the energy storage performance of dielectrics for capacitor applications.
We present a new type of torsional soft morphing actuator designed and fabricated by twisted shape memory alloy (SMA) wires embedded in polydimethylsiloxane matrix. The design and fabrication process of the proposed soft morphing actuator are presented with investigations of its working mechanism. Actuation performance was evaluated with respect to the temporal response, the maximum torsional deformation under an applied electric current, and various design parameters including the twist direction, wire diameter, helical pitch of the SMA wire, and the actuator’s thickness and length. We demonstrate potential applications of the proposed soft morphing actuator as a soft morphing wing and airfoil. The proposed actuator will aid in the development of soft actuators, soft robotics, and other relevant scientific and engineering applications.
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501 members
Mohammed Nazim
  • Department of Material Design Engineering
Young-Gwang Yunjeh Ko
  • Department of Polymer Science and Engineering
han-jeong Hwang
  • Department of Medical IT Convergence Engineering
Yeon-Mo Yang
  • School of Electronic Engineering
61 Daehak-ro, 39177, Gumi, Gyeongsangbuk-do, South Korea
Head of institution
Yeungshik Kim