• Elastomers and Composites
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• 제58권4호
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• pp.161-172
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• 2023

Because particulate matter has emerged as a major contributor to air pollution, the tire industry has conducted studies to reduce particulate matters from tires by improving tire performance. In this study, we compared the conventional blending method, in which rubber, filler, and additives are mixed simultaneously, to the Y-blending method, in which masterbatches are blended. We manufactured carbon black (CB)-filled natural rubber (NR)/butadiene rubber (BR) blend and silica-filled epoxidized NR/BR blend compounds to compare the effects of the two blending methods on the physical properties of the compounds and the amount of particulate matter generated. The Y-blending method provided uniform filler distribution in the heterogeneous rubber matrix, improved processability, and exhibited low rolling resistance. This method also improved physical properties owing to the excellent filler-rubber interaction. The results obtained from measuring the generation of particulate matter indicated that, the Y-blending method reduced PM_2.5 particulate matter generation from the CB-filled and silica-filled compounds by 38% and 60%, and that of PM₁₀ by 29% and 67%, respectively. This confirmed the excellence of the Y-blending method regarding the physical properties of truck bus radial tire tread compounds and reduced particulate matter generated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권2호
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• pp.397-419
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• 2024

Online learning has become a widespread practice for students and teachers in acquiring and delivering knowledge. Education platforms have become prominent in the 21st century with the evolution of technology and the accessibility to online learning. As a result, various learning management systems (LMSs) have been introduced to facilitate online interaction between users. For instance, communication between students and teachers at school. However, there is a need to emphasise user engagement in LMS to enhance the online learning experience amongst students since the design of LMS affects user engagement. This study utilised a systematic literature review (SLR) that examined 74 articles published between 2014 and 2023, focusing on cross-cultural design (CCD), user-centred design (UCD), and usability in LMS design. This study aimed to review CCD and its association with UCD, user interfaces (UI), and user experience (UX) in the context of LMS. CCD has been introduced as an approach to design that embraces different cultures, languages, and social contexts, while UCD plays a significant role in defining user engagement for LMS. All elements in CCD and UCD help create a better user experience for LMS. Besides, this study reviewed the usability of selected LMS to give insights to developers in creating a positive user engagement. An insight into cultural factors that influence the usability of LMS has revealed their value for LMS design, such as the UI/UX elements. Initially, this study may guide future researchers in improving education quality by emphasising CCD and LMS usability, which can enhance user engagement.

• Human Ecology Research
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• 제62권2호
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• pp.217-231
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• 2024

The aims of this study were to identify (a) the social network contact frequency of the elderly with children, relatives, and friends; (b) the impact of contact frequency (face-to-face/non-face-to-face) on life satisfaction of the elderly; and (c) the moderating effect of digital capabilities of the elderly on the relationship between social contact frequency and life satisfaction. Data were obtained from the National Survey of Older Koreans 2020. The sample comprised 6,119 adults aged 65+ who were in single or couple households. The principal findings were as follows. First, couple households, higher levels of education, and better health status increased life satisfaction of the elderly. Second, the higher the frequency of face-to-face contact with children and the higher the frequency of non-face-to-face contact with friends, the more positive the effect on life satisfaction of the elderly. Third, the interaction effect of the digital capabilities of the elderly differed according to children, relatives and friends. There was a significant and positive moderating effect on the relationship between life satisfaction and the frequency of face-to-face/non-face-to-face contact with children and the frequency of face-to-face contact with relatives. Conversely, there was a significant negative effect on the relationship between life satisfaction and the frequency of face-to-face/non-face-to-face contact with friends. By examining the impact of non-face-to-face contact on life satisfaction of the elderly in the era of digital transformation, the findings have significance in that they provide basic data to support policies and education programs aimed at improving the digital capabilities of the elderly.

• 대한약침학회지
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• 제27권2호
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• pp.91-100
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• 2024

Objectives: Candida albicans is an opportunistic pathogen that occurs as harmless commensals in the intestine, urogenital tract, and skin. It has been influenced by a variety of host conditions and has now evolved as a resistant strain. The aim of this study was thus detect the fluconazole resistant C. albicans from the root caries specimens and to computationally evaluate the interactions of an opaque-phase ABC transporter protein with the Psidium guajava bio-active compounds. Methods: 20 carious scrapings were collected from patients with root caries and processed for the isolation of C. albicans and was screened for fluconazole resistance. Genomic DNA was extracted and molecular characterization of Cdrp1 and Cdrp2 was done by PCR amplification. P. guajava methanolic extract was checked for the antifungal efficacy against the resistant strain of C. albicans. Further in-silico docking involves retrieval of ABC transporter protein and ligand optimization, molinspiration assessment on drug likeness, docking simulations and visualizations. Results: 65% of the samples showed the presence of C.albicans and 2 strains were fluconazole resistant. Crude methanolic extract of P. guajava was found to be promising against the fluconazole resistant strains of C. albicans. In-silico docking analysis showed that Myricetin was a promising candidate with a high docking score and other drug ligand interaction scores. Conclusion: The current study emphasizes that bioactive compounds from Psidium guajava to be a promising candidate for treating candidiasis in fluconazole resistant strains of C. albicans However, further in-vivo studies have to be implemented for the experimental validation of the same in improving the oral health and hygiene.

• 한국ITS학회 논문지
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• 제22권6호
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• pp.264-283
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• 2023

자율주행차량 사고는 일반차량 사고와 다르게 기술적 문제, 환경, 운전자와의 상호작용 등 다양한 요인에 기인한 사고 발생 가능성이 존재한다. 향후 자율주행 기술의 진보로 기존의 사고원인 이외에도 새로운 이슈들이 대두될 것으로 예상되며, 이에 대응하기 위한 다양한 시나리오 기반의 접근법이 필요하다. 본 연구에서는 자율주행 사고 리포트인, CA DMV collision report와 자율주행모드 해제 보고서인 Disengagement report, 자율주행 실제 사고영상을 수집하여 자율주행차량 교통사고 시나리오를 개발하였다. 시나리오는 ISO 26262의 기능안전 시스템 failure mode에 기반하여 도출되었으며, 자율주행 기능의 다양한 이슈를 반영하고자 하였다. 본 연구를 통해 도출된 자율주행차량 시나리오는 향후 다양한 자율주행차량 교통사고 예방과 대비에 기여할 뿐만 아니라 자율주행 기술의 안전성을 향상시키는 데 중요한 역할을 할 것으로 기대한다.

• Earthquakes and Structures
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• 제26권3호
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• pp.239-249
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• 2024

A new layered shear continuum model box was developed to address the dynamic response issues of buried oil and gas pipelines under multi-point excitation. Vibration table tests were conducted to investigate the seismic response of buried pipelines and the surrounding soil under longitudinal multi-point excitation. A nonlinear model of the pipeline-soil interaction was established using ABAQUS finite element software for simulation and analysis. The seismic response characteristics of the pipeline and soil under longitudinal multi-point excitation were clarified through vibration table tests and simulation. The results showed good consistency between the simulation and tests. The acceleration of the soil and pipeline exhibited amplification effects at loading levels of 0.1 g and 0.2 g, which significantly reduced at loading levels of 0.4 g and 0.62 g. The peak acceleration increased with increasing loading levels, and the peak frequency was in the low-frequency range of 0 Hz to 10 Hz. The amplitude in the frequency range of 10 Hz to 50 Hz showed a significant decreasing trend. The displacement peak curve of the soil increased with the loading level, and the nonlinearity of the soil resulted in a slower growth rate of displacement. The strain curve of the pipeline exhibited a parabolic shape, with the strain in the middle of the pipeline about 3 to 3.5 times larger than that on both sides. This study provides an effective theoretical basis and test basis for improving the seismic resistance of buried oil and gas pipelines.

• Advances in aircraft and spacecraft science
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• 제11권2호
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• pp.153-175
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• 2024

In jet engines, turbine blade cooling has an extremely important role. The pin-fin array, which is situated close to the trailing edge of the blade, aids in internal cooling of the gas turbine blades and preserves the structural integrity of the blade. Previous studies often focused on pin-fin configurations, but the current research focuses on improving the geometry at the endwalls to reduce wake vortices behind the pin-fins and enhance heat transfer at the endwalls location. Using the k-ω turbulence model, a numerical study was conducted on a ribbed shape situated on the walls between pin-fin arrays, spanning a Reynolds number range of 7400 to 36000, in order to determine the heat transport characteristics. The heat transfer efficiency coefficient and Nusselt number increase dramatically with the revised wall configuration, according to the numerical data. The channel's heat transfer efficiency is increased by enlarging the heat transfer areas near the pin-fins and by the interaction of the flow with the endwalls. The addition of ribs causes the Nusselt number of the new model to climb from 78% to 96% at the previously given Reynolds numbers, and the heat transfer efficiency index to rise from 60% to 73%. The height (Hr), position (Lr), forward width (Wf), and backward width (Wb) of the ribs are among the geometric elements that were looked at in order to determine how they affected the performance of heat transmission. In comparison to the reference design, the parametric study results demonstrate that the best forward width (Wf/R=18.75%) and backward width (Wb/R=31.25%) increase the heat transfer efficiency index by 0.4% and 1.3%, respectively.

• 문화기술의 융합
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• 제10권4호
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• pp.601-606
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• 2024

오늘날 정부는 디지털 기술을 적극적으로 활용하여 국가의 발전을 촉진하는 디지털 정부로 진화하고 있다. 정부 웹사이트는 개인과 정부의 상호작용을 혁신적으로 재정립하는 핵심적인 요소로 작용하고 있는 가운데, 정부 웹사이트 챗봇은 시민들이 쉽게 정보를 얻을 수 있도록 하는 중요한 역할을 하고 있다. 그러나 국가 R&D 지식정보 포털인 NTIS의 챗봇 ND는 사용률이 낮은 편이다. 본 연구는 챗봇 ND의 사용성 문제를 해결하기 위해 사용자 여정 지도를 기반으로 한 프레임워크를 제안한다. 사용자 여정을 '사용 전- 사용 중- 사용 후' 단계로 구분하고, 각 단계에서 사용자들이 불편을 겪는 지점을 파악하여 개선된 사용자 경험을 제공하는 것을 목표로 한다.

• Elastomers and Composites
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• 제59권2호
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• pp.64-72
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• 2024

As air pollution continues to increase owing to increasing traffic centered in urban areas, the tire industry is researching methods to reduce particulate matter. In this study, functionalized lithium butadiene rubber (F-LiBR) was applied to a natural rubber (NR)/butadiene rubber (BR) blend compound often used in truck bus radial (TBR) tire treads. The effect of the functional group that can react with carbon black (CB) in BR was investigated in terms of the dispersion of CB and the compound performance, including the generation of particulate matter. Compounds that were substituted with F-LiBR exhibited enhanced interaction with CB, resulting in excellent filler dispersion. Although F-LiBR exhibited lower crosslinking density and inferior abrasion resistance due to its high vinyl content, the compound with 30 phr of F-LiBR was advantageous in terms of its rolling resistance due to the excellent filler dispersion, which was also effective in reducing the amount of generated particulate matter (up to 56% reduction for PM_2.5, and 67% reduction for PM₁₀). The results confirmed the benefits of the introduction of functional groups into TBR tire tread compounds, which can aid in improving the fuel efficiency and reducing particulate matter generation.

• Biomolecules & Therapeutics
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• 제32권5호
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• pp.509-522
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• 2024

Decellularized matrix transplantation has emerged as a promising therapeutic approach for repairing tissue defects, with numerous studies assessing its safety and efficacy in both animal models and clinical settings. The host immune response elicited by decellularized matrix grafts of natural biological origin plays a crucial role in determining the success of tissue repair, influenced by matrix heterogeneity and the inflammatory microenvironment of the wound. However, the specific immunologic mechanisms underlying the interaction between decellularized matrix grafts and the host immune system remain elusive. This article reviews the sources of decellularized matrices, available decellularization techniques, and residual immunogenic components. It focuses on the host immune response following decellularized matrix transplantation, with emphasis on the key mechanisms of Toll-like receptor, T-cell receptor, and TGF-β/SMAD signaling in the stages of post-transplantation immunorecognition, immunomodulation, and tissue repair, respectively. Furthermore, it highlights the innovative roles of TLR10 and miR-29a-3p in improving transplantation outcomes. An in-depth understanding of the molecular mechanisms underlying the host immune response after decellularized matrix transplantation provides new directions for the repair of tissue defects.