• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.4
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• pp.469-476
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• 2023

Soil plasticity models for cyclic and dynamic loads are essential in non-linear numerical analysis of geotechnical structures. While a single yield surface model shows a linear behavior for cyclic loads, J₂-bounding surface plasticity model with zero elastic region can effectively simulate a nonlinearity of the ground response with the same material properties. The radius of the yield surface inside the boundary surface converged to 0 to make the elastic region disappear, and plastic hardening modulus and dilatancy define plastic strain increment. This paper presents the stress-strain incremental equation of the developed model, and derives plastic hardening modulus for the hyperbolic model. The comparative analyses of the triaxial compression test and the shallow foundation under the cyclic load can show stable numerical convergence, consistency with the theoretical solution, and hysteresis behavior. In addition, plastic hardening modulus for the modified hyperbolic function is presented, and a methodology to estimate model variables conforming 1D equivalent linear model is proposed for numerical modeling of the multi-dimensional behavior of the ground.

• Advances in nano research
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• v.15 no.1
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• pp.1-13
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• 2023

Ti₃C₂T_x MXene, a 2D material, is known to exhibit unique characteristics that are strongly dependent on surface termination groups. Here, we developed a novel annealing approach with Ca as a reducing agent to simultaneously remove F and O groups from the surface of multilayered MXene powder. Unlike H₂ annealing that removes F effectively but has difficulty in removing O, annealing with Ca effectively removed both O and F. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy revealed that the proposed approach effectively removed F and O from the MXene powder. The results of O/N analyses showed that the O concentration decreased by 57.5% (from 2.66 to 1.13 wt%). In addition, XPS fitting showed that the volume fraction of metal oxides (TiO₂ and Al₂O₃) decreased, while surface termination groups (-O and -OH) were enhanced, which could increase the hydrophilic and adsorption properties of the MXene. These findings suggest that when F and O are removed from the MXene powder, the interlayer spacing of its lattice structure increases. The proposed treatment also resulted in an increase in the specific surface area (from 5.17 to 10.98 m²/g), with an increase in oxidation resistance temperature in air from ~436 to ~667 ℃. The benefits of this novel technology were verified by demonstrating the significantly improved cyclic charge-discharge characteristics of a lithium-ion battery with a Ca-treated MXene electrode.

• Journal of People, Plants, and Environment
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• v.22 no.4
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• pp.341-354
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• 2019

Urban agriculture, which promotes communication in vulnerable classes and the formation of social networks has been gaining attention with an emphasis on healthy city, elderly-friendly city, safe city and happy city as future keywords about urban life. There is a growing interest in public awareness in many areas such as health, society, economy, and ecology. As an attempt to improve the diversity of urban gardens, this study begins with collecting suitable crops for urban gardens from "Imwongyeongjeji (林園經濟志)," an encyclopedia written by Yoo-Ku Seo, a scholar in the 18-19th century. Out of those recorded in "Gwanhyuji (灌畦志)," 128 kinds of crops with linkage of the historical achievements of the realists who gave their priority to public welfare were selected and 53 crops which had traditionality, historicality, health functionality and popularity were finally selected. The properties (cold, warm, clam) of the selected crops were evenly distributed, and there was no crop that was hot and cool. In addition, the number of crops that have a sweet taste was the highest, followed by spicy and bitter, but there was no salty vegetable, which can be attributed to the fact that 12 namuls (wild vegetables) that grow in seas were excluded in this study since they were not suitable for urban gardens. Urban gardens can be transformed from those that focus on primary production and secondary consumption activities into a new resource that offers educational and traditional values by applying humanities to urban agriculture as a content resource in the era of cultural consilience and convergence. It is expected to satisfy urban residents' intellectual and participatory needs and to enhance the diversity and utility of urban gardens by applying traditional knowledge to a new model of urban agriculture. We hope that further research will be conducted to develop new types and models of urban agriculture going forward.

• Korean Journal of Agricultural Science
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• v.50 no.2
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• pp.281-294
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• 2023

As a byproduct obtained from cheese manufacture, whey protein was developed as a functional food that contains multi-functional proteins. In this study, the biochemical activity of fermented milk prepared by fortifying whey protein with excellent physiological activity was investigated. Immunoglobulin (IgG) content was higher in 10% fortified whey protein fermented milk than in the control. The viable cell counts were 20% higher in the fermented milk with 10% fortified whey protein than in the control group. The antibacterial effect of 10% fortified whey protein fermented milk compared to the control group was shown to be effective against four pathogenic microorganisms, Escherichia coli (KCTC1039), Pseudomonas aeruginosa 530, Salmonela Typhimurium (KCTC3216), and Staphylococcus aureus (KCTC1621). The antioxidant effect by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities wasincreased two-fold in 10% fortified whey protein fermented milk compared to the control. The 10% fortified whey protein fermented milk inhibited the expression of the inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α, and induced nitric oxide synthase [iNOS]) in a concentration-dependent manner. In a piglets feeding test, the weight gain with 10% fortified whey protein fermented milk was increased by 18% compared to the control group, and no diarrhea symptoms appeared. Our results clearly demonstrated that 10% fortified whey protein fermented milk could be a useful functional ingredient for improving health.

• Composites Research
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• v.36 no.6
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• pp.408-415
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• 2023

The formation of bonding configurations such as pyridinic-N, pyrrolic-N, and graphitic-N by nitrogen doping plays a crucial role in imparting distinct physical properties to carbon nanomaterials. In this study, we propose a simple and cost-effective approach to regulate nitrogen dopant configurations in carbon nanotubes (CNTs) by mixing melamine as a dopant source. We employed three distinct mechanical mixing techniques, namely magnetic stirring, bath sonication and tip sonication. The higher the ratio of melamine to CNT, the higher the ratio of Pyrrolic-N, and when mixed through stirring, the highest ratio of Pyridinic-N was shown. The facile method proposed in this study, which can easily form various types of nitrogen dopants in carbon nanotubes, is expected to facilitate the application of nitrogen-doped carbon nanomaterials.

• Steel and Composite Structures
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• v.51 no.1
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• pp.73-91
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• 2024

This paper has focused on presenting vibration analysis of trapezoidal sandwich plates with a damaged core and FG wavy CNT-reinforced face sheets. A damage model is introduced to provide an analytical description of an irreversible rheological process that causes the decay of the mechanical properties, in terms of engineering constants. An isotropic damage is considered for the core of the sandwich structure. The classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The First-order shear deformation theory of plate is utilized to establish governing partial differential equations and boundary conditions for the trapezoidal plate. The governing equations together with related boundary conditions are discretized using a mapping-generalized differential quadrature (GDQ) method in spatial domain. Then natural frequencies of the trapezoidal sandwich plates are obtained using GDQ method. Validity of the current study is evaluated by comparing its numerical results with those available in the literature. After demonstrating the convergence and accuracy of the method, different parametric studies for laminated trapezoidal structure including carbon nanotubes waviness (0≤w≤1), CNT aspect ratio (0≤AR≤4000), face sheet to core thickness ratio (0.1 ≤ ${\frac{h_f}{h_c}}$ ≤ 0.5), trapezoidal side angles (30° ≤ α, β ≤ 90°) and damaged parameter (0 ≤ D < 1) are carried out. It is explicated that the damaged core and weight fraction, carbon nanotubes (CNTs) waviness and CNT aspect ratio can significantly affect the vibrational behavior of the sandwich structure. Results show that by increasing the values of waviness index (w), normalized natural frequency of the structure decreases, and the straight CNT (w=0) gives the highest frequency. For an overall comprehension on vibration of laminated trapezoidal plates, some selected vibration mode shapes were graphically represented in this study.

• Information Systems Review
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• v.22 no.3
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• pp.15-30
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• 2020

In the real estate industry, the latest changes in the Fourth Industrial Revolution, such as big data analytics, machine learning, and VR (virtual reality), combine to bring about industry change. Proptech is a new term combining properties and technology. This study aims to derive and analyze from a comprehensive perspective the quality factors (systems, services, interfaces, information) for mobile real estate brokerage services that are well known and used in the domestic market. The surveys in this study were conducted online and offline and a total of 161 samples were used for statistical analysis. As a result, all hypotheses were approved to except system quality and service quality. The results show that the domestic proptech companies who are mostly focused on real estate brokerage services, peer-to-peer lending, advertising platforms and apartments need to grow in various fields of proptech business of other countries including Europe, USA and China.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.1
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• pp.29-36
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• 2024

This study was carried out to identify the anti-inflammatory effects of Ishige foliacea (I. foliacea) extract on skin using RAW 264.7 cells. The anti-inflammatory effects of I. foliacea extract on RAW 264.7 cells were assessed by cell viability assay, mRNA expressions, and nitric oxide (NO)/prostaglandin E₂ (PGE₂) productions. The anti-inflammatory effects of I. foliacea extract were elucidated by analysis of IL-1α/IL-1β/IL-6/TNFα gene expressions and PGE₂/NO production. Quantitative real-time polymerase chain reaction showed that I. foliacea extract decreased the gene expression levels of iNOS/COX2/IL-1α/IL-1β and IL-6. Furthermore, PGE₂/NO production also revealed that I. foliacea extract exhibited anti-inflammatory properties. These results suggest that I. foliacea extract is an anti-inflammatory compound. It could be a potent cosmeceutical material for anti-inflammatory effects. Further studies on the anti-inflammatory mechanisms of broadleaf extracts are expected to help identify pharmacological mechanisms related to inflammation in addition to cosmeceuticals.

• The Research Journal of the Costume Culture
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• v.32 no.1
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• pp.108-123
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• 2024

This study aimed to explore sustainable fashion design plans and directions by analyzing Marine Serre's collection. Previous research was reviewed to derive classifications of the aesthetic characteristics of sustainable fashion design. This classification was then used to analyze the characteristics of the Marine Serre collection. Design analysis was conducted on Marine Serre's 2018 FW to 2023 SS collections. Marine Serre's sustainability characteristics are functionality, surprise, handicraft, and inclusion. The results are as follows. First, functionality is the highest among the four characteristics and includes the functionality of movement, the functionality of form, and futurism. This characteristic was observed in the use of all-in-one body suits, pockets, and workwear, showing the will and values of designers who value daily activity. Second, surprise includes the scarcity of materials and the unexpectedness of composition. The value of the clothing is enhanced by the use of scarce materials not typically used in clothing. In addition, Marine Serre is highly regarded for expanding clothing into life by incorporating material upcycling into the theme of the collection. Third, handcrafted features include exaggerated decorations, logo, retro designs, and natural properties, and intentional utilization is differentiated. Marine Serre's signature pattern suggests a suitable expression for the fabric to use the crescent moon for the season. Fourth, the collection expresses themes of inclusivity and cultural diversity. The results indicate that Marine Serre wants to contribute to a better future characterized by global coexistence.

• Food Science and Industry
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• v.53 no.1
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• pp.2-32
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• 2020

In recent years, significant importance has been given to chitooligosaccharides (COS) due to its potent notable biological applications. COS can be derived from chitosan which is commonly produced by partially hydrolyzed products from crustacean shells. In order to produce COS, there are several approaches including chemical and enzymatic methods which are the two most common choices. In this regard, several new methods were intended to be promoted which use the enzymatic hydrolysis with a lower cost and desired properties. Hence, the dual reactor system has gained more attention than other newly developed technologies. Enzymatic hydrolysis derived COS possesses important biological activities such as anticancer, antioxidant, anti-hypersentive, anti-dementia (Altzheimer's disease), anti-diabeties, anti-allergy, anti-inflammatory, etc. Results strongly suggest that properties of COS can be potential materials for nutraceutical, pharmaceutical, and cosmeceutical product development.