• 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.

• Composites Research
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• v.37 no.3
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• pp.190-196
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• 2024

The bipolar plate is a crucial element of the vanadium redox flow battery (VRFB) as it serves as both the electrical conduit and the structural support for the cell within the VRFB stack. Although, the graphite material is primarily used for the bipolar plate due to its excellent electrical conductivity, a significant limitation of performance of the VRFB is present due to high interfacial contact resistance (ICR) arises between the electrode and bipolar plate in the cell stack. This study aims to develop an integrated electrode-bipolar plate assembly that will address the limitations of the ICR. The integrated assembly was constructed using a single carbon felt with thermoplastic and thermoset polymers utilizing hot press method. Experimental results verify that the bipolar plate assembly exhibits reduced area specific resistance (ASR) due to the continuous electrical path. Additionally, from the charge/discharge cell test results, the integrated assembly shows improved cell performance. Therefore, the developed integrated electrode-bipolar plate assembly can serve as a substitute for the conventional bipolar plate and electrode assembly.

• 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.

• 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.

• 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.

• Korean Journal of Heritage: History & Science
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• v.55 no.1
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• pp.175-198
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• 2022

With the development of technology, the methods of digitally converting various forms of analog information have become common. As a result, the concept of recording, building, and reproducing data in a virtual space, such as digital heritage and digital reconstruction, has been actively used in the preservation and research of various cultural heritages. However, there are few existing research results that suggest optimal scanners for small and medium-sized relics. In addition, scanner prices are not cheap for researchers to use, so there are not many related studies. The 3D scanner specifications have a great influence on the quality of the 3D model. In particular, since the state of light reflected on the surface of the object varies depending on the type of light source used in the scanner, using a scanner suitable for the characteristics of the object is the way to increase the efficiency of the work. Therefore, this paper conducted a study on nine small and medium-sized buried cultural properties of various materials, including earthenware and porcelain, by period, to examine the differences in quality of the four types of 3D scanners. As a result of the study, optical scanners and small and medium-sized object scanners were the most suitable digital records of the small and medium-sized relics. Optical scanners are excellent in both mesh and texture but have the disadvantage of being very expensive and not portable. The handheld method had the advantage of excellent portability and speed. When considering the results compared to the price, the small and medium-sized object scanner was the best. It was the photo room measurement that was able to obtain the 3D model at the lowest cost. 3D scanning technology can be largely used to produce digital drawings of relics, restore and duplicate cultural properties, and build databases. This study is meaningful in that it contributed to the use of scanners most suitable for buried cultural properties by material and period for the active use of 3D scanning technology in cultural heritage.

• Composites Research
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• v.35 no.4
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• pp.248-254
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• 2022

In this study, TiB₂-steel composite with high-fractional TiB₂ reinforcement was fabricated by gas pressure infiltration process and the microstructure analysis and compressive strength and hardness were evaluated. To elucidate the correlation between microstructure and mechanical properties for fabricated composite, after the compression test of TiB₂-steel composite, the fracture surface was analyzed and the fracture behavior on compression test was predicted. As a result of the compression fracture surface analysis, interfacial failure trace between the steel matrix and the reinforcement was observed, and the interface between the steel matrix and the reinforcement was analyzed using TEM. From the result of microstructure analysis on the fabricated composite, it was confirmed that, in addition to TiB₂ reinforcement and steel matrix, TiC phase and coarse (Fe,M)₂B (M=Cr,Mn) phase were formed. Throughout the thermodynamic calculation, it was confirmed that TiC and (Fe,M)₂B can be formed as a stable phase under the process condition. The fabricated TiB₂-steel composite had a significantly increased hardness, and the compressive strength and Young's modulus were improved by 3.07 times and 1.95 times, respectively, compared to steel matrix. It seems that the coarse (Fe,M)₂B (M=Cr,Mn) phase formed throughout the composite causes the deterioration of mechanical properties, and by controlling the formation of the (Fe,M)₂B (M=Cr,Mn) phase, it is judged that the mechanical properties of the TiB₂-steel composite can be further improved.