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923 result(s) for "Lee, Jun-Won"
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Factors affecting user acceptance for NFC mobile wallets in the U.S. and Korea
Purpose - The purpose of this paper is to identify the factors affecting user acceptance for NFC mobile wallets in both Korean and US markets. Design/methodology/approach - The proposed model extends the UTAUT2 model with new constructs of credibility (CR) and service smartness (SS). This study was analyzed using partial least square structural equation modeling on data collected from 701 college students between the ages of 18 and 29. Findings - The results of this study demonstrate that performance expectancy (PE), effort expectancy (EE), CR, SS and habit (HB) have strong positive relationships with a user's behavioral intention to use NFC mobile wallets. Comparing the results of the USA and South Korea, there are different results regarding PE and CR. Research limitations/implications - This study shows that all factors except social influence (SI) have significant positive relationships with the intention to adopt NFC mobile wallets: Among the original UTUAT2 factors, PE, EE and HB are important determinants of NFC mobile wallet adoption and the new constructs, CR and SS, are significant determinants that influence BI. However, the target respondents are limited to college students of South Korea and the USA Thus, caution should be used when applying the results of this study towards less ICT developed countries and towards different age groups. Practical implications - This study provides multiple practical contributions. First, this study emphasizes HB as the strongest factor for adopting NFC mobile wallets in both South Korea and the USA Second, this study also highlights the importance of SS. Third, this study reveals that SI is not associated with the adoption of NFC mobile wallets. Fourth, nationality differences between the USA and South Korea account for the differences in consumer behaviors. Originality/value - This study has two main contributions: First, this study introduces a modified UTAUT2 model with two new variables (CR and SS) useful for NFC mobile wallets. Second, this study compares the results of partial least square structured equation models (PLS-SEM) of the two nationality groups, South Korea and the USA.
Extended model to explain customer attitude toward NFT and moderating effect of technology optimism
PurposeThis study empirically examined consumer adoption attitudes and behaviors toward nonfungible tokens (NFTs). Findings indicate that consumer attitudes toward NFTs are influenced by perceived usefulness, reliability and profit expectancy and that strong attitudes are associated with purchase intentions. Additionally, the relationship between attitudes and purchase intentions was moderated by technology optimism.Design/methodology/approachThe authors utilized a partial least squares (PLS) model to examine the hypotheses in this empirical analysis. Obtaining a sample of actual NFT holders or experienced users is challenging. A total of 105 individuals participated in the study as valid responders by answering the screening question in the questionnaire. The authors opted for the PLS model as a research approach due to the limited size of the consumer population in the NFT market.FindingsThis study discovered that the adoption of NFTs was affected by technical aspects such as usefulness and reliability and the potential for future asset growth. Furthermore, the degree of attitude-to-intention conversion varied based on optimism, an inherent characteristic.Research limitations/implicationsThis study offers valuable insights for NFT owners, content providers and trading firms. For the NFT market to expand, it must meet consumers' expectations for the desired content features and asset investment attributes. Additionally, customer targeting strategies should attract and appeal to technology enthusiasts with an optimistic outlook on technology.Originality/valueThe authors conducted an initial empirical analysis of actual NFT consumers, an area of research studied sparingly despite its significance.
Carbon nanotube-reduced graphene oxide fiber with high torsional strength from rheological hierarchy control
High torsional strength fibers are of practical interest for applications such as artificial muscles, electric generators, and actuators. Herein, we maximize torsional strength by understanding, measuring, and overcoming rheological thresholds of nanocarbon (nanotube/graphene oxide) dopes. The formed fibers show enhanced structure across multiple length scales, modified hierarchy, and improved mechanical properties. In particular, the torsional properties were examined, with high shear strength (914 MPa) attributed to nanotubes but magnified by their structure, intercalating graphene sheets. This design approach has the potential to realize the hierarchical dimensional hybrids, and may also be useful to build the effective network structure of heterogeneous materials. Fibers with high torsional strength are of practical interest for artificial muscles, electric generators, actuators, etc. Here, the authors optimize torsional strength by overcoming rheological thresholds of nanocarbon (nanotube/graphene oxide) dopes.
Why do consumers buy NFTs?: Multi-path of attitude and the bandwagon effect
PurposeThe non-fungible token (NFT) market has been multiplying in recent years. NFTs are tokens stored on a blockchain network based on smart contract technology that can be used to represent ownership of digital assets and cannot be changed like-for-like. With NFTs, all recorded digital properties can be freely traded and stored with values, making them possible to increase content transactions' privacy and security. In addition, NFTs engender new ways to organize, consume, share and store digital content. Despite the rapid growth of the NFT market, related consumer behaviors have yet to be well-known and relevant academic research results are very scarce. This study aims to explain how NFT fits with blockchain and cryptocurrency and how consumers accept it. This paper also develops a structured causal model with multiple paths to explain the antecedents and attitude variables for NFT acceptance.Design/methodology/approachThe data collection was conducted from 542 young consumers in Korea via an online survey. The structural equation modeling method was used to analyze the hypotheses.FindingsAttitudes toward technology and assets positively affect NFT purchase behavioral intentions. Additionally, symbolic driver affects behavioral intention directly.Originality/valueThe results expanded the understanding of the NFT market and consumers, which are still in their early stages. They also provide valuable insights for establishing future market strategies for NFT.
Feasibility of microencapsulated phytochemical as disinfectant for inhibition of Candida albicans proliferation on denture base produced by digital light processing
A proper disinfection of denture is vital to prevent a fungal infection. A study on the feasibility of microencapsulated phytochemical as complementary disinfectant and its interaction with effervescent tablet immersion on denture base resin is lacking. The aim of this study was to examine the feasibility of phytochemical-filled microcapsules as disinfectant for the inhibition of Candida albicans (C. albicans) attachment on the denture base produced by digital light processing (DLP). 54 denture base specimens uniformly mixed with or without 5wt% phytochemical-filled microcapsules were prepared using DLP. Fungal cells were inoculated onto the surfaces of the specimens, which were divided into three different disinfection treatment groups (n = 9): 1) none, 2) sterile tap water immersion for 15 min, and 3) effervescent tablet immersion for 15 min. After each treatment, the biofilm on denture surface was stained with a crystal violet solution to measure the absorbance. The number of fungal colonies was counted as colony-forming units (CFU) per mL. Morphological changes were examined by microscopy. An aligned rank transform analysis of variance was performed to analyze the interaction of presence of microcapsule and disinfection condition, with statistical significance set at P < 0.05. Both for the absorbance and CFU, there was no significant interaction between the presence of microcapsules and disinfection conditions (P = 0.543 and P = 0.077, respectively). The presence of microcapsules was statistically significant (both P < 0.001), while the effect of disinfection condition was not significant (P = 0.165 and P = 0.189, respectively). Morphological changes in fungi were detected in the groups containing microcapsules, whereas undamaged hyphal structures were found in those without microcapsules, irrespective of disinfection treatments. The presence of phytochemical-filled microcapsules significantly reduced the adhesion of C. albicans and inhibited its proliferation on denture surfaces, regardless of disinfection conditions.
Dopant-specific unzipping of carbon nanotubes for intact crystalline graphene nanostructures
Atomic level engineering of graphene-based materials is in high demand to enable customize structures and properties for different applications. Unzipping of the graphene plane is a potential means to this end, but uncontrollable damage of the two-dimensional crystalline framework during harsh unzipping reaction has remained a key challenge. Here we present heteroatom dopant-specific unzipping of carbon nanotubes as a reliable and controllable route to customized intact crystalline graphene-based nanostructures. Substitutional pyridinic nitrogen dopant sites at carbon nanotubes can selectively initiate the unzipping of graphene side walls at a relatively low electrochemical potential (0.6 V). The resultant nanostructures consisting of unzipped graphene nanoribbons wrapping around carbon nanotube cores maintain the intact two-dimensional crystallinity with well-defined atomic configuration at the unzipped edges. Large surface area and robust electrical connectivity of the synergistic nanostructure demonstrate ultrahigh-power supercapacitor performance, which can serve for AC filtering with the record high rate capability of −85° of phase angle at 120 Hz. Atomic level engineering of graphene-based materials is highly demanded for the customized structures and properties. Here, the authors show heteroatom dopant-specific unzipping of carbon nanotubes as a reliable and controllable route to customized 'intact crystalline' graphene-based nanostructures.
Assessment of reliability and validity of the 5-scale grading system of the point-of-care immunoassay for tear matrix metalloproteinase-9
We evaluated the reliability and validity of the 5-scale grading system to interpret the point-of-care immunoassay for tear matrix metalloproteinase (MMP)-9. Six observers graded red bands of photographs of the readout window in MMP-9 immunoassay kit (InflammaDry) two times with 2-week interval based on the 5-scale grading system (i.e. grade 0–4). Interobserver and intraobserver reliability were evaluated using intraclass correlation coefficients. The interobserver agreements were analyzed according to the severity of tear MMP-9 expression. To validate the system, a concentration calibration curve was made using MMP-9 solutions with reference concentrations, then the distribution of MMP-9 concentrations was analyzed according to the 5-scale grading system. Both intraobserver and interobserver reliability was excellent. The readout grades were significantly correlated with the quantified colorimetric densities. The interobserver variance of readout grades had no correlation with the severity of the measured densities. The band density continued to increase up to a maximal concentration (i.e. 5000 ng/mL) according to the calibration curve. The difference of grades reflected the change of MMP-9 concentrations sensitively, especially between grade 2 and 4. Together, our data indicate that the subjective 5-scale grading system in the point-of-care MMP-9 immunoassay is an easy and reliable method with acceptable accuracy.
Validation of the MAGGIC (Meta-Analysis Global Group in Chronic Heart Failure) heart failure risk score and the effect of adding natriuretic peptide for predicting mortality after discharge in hospitalized patients with heart failure
In clinical practice, a risk prediction model is an effective solitary program to predict prognosis in particular patient groups. B-type natriuretic peptide (BNP)and N-terminal pro-b-type natriuretic peptide (NT-proBNP) are widely recognized outcome-predicting factors for patients with heart failure (HF).This study derived external validation of a risk score to predict 1-year mortality after discharge in hospitalized patients with HF using the Meta-analysis Global Group in Chronic Heart Failure (MAGGIC)program data. We also assessed the effect of adding BNP or NT-proBNP to this risk score model in a Korean HF registry population. We included 5625 patients from the Korean acute heart failure registry (KorAHF) and excluded those who died in hospital. The MAGGIC constructed a risk score to predict mortality in patients with HF by using 13 routinely available patient characteristics (age, gender, diabetes, chronic obstructive pulmonary disorder (COPD), HF diagnosed within the last 18 months, current smoker, NYHA class, use of beta blocker, ACEI or ARB, body mass index, systolic blood pressure, creatinine, and EF). We added BNP or NT-proBNP, which are the most important biomarkers, to the MAGGIC risk scoring system in patients with HF. The outcome measure was 1-year mortality. In multivariable analysis, BNP or NT-proBNP independently predicted death. The risk score was significantly varied between alive and dead groups (30.61 ± 6.32 vs. 24.80 ± 6.81, p < 0.001). After the conjoint use of BNP or NT-proBNP and MAGGIC risk score in patients with HF, a significant difference in risk score was noted (31.23 ± 6.46 vs. 25.25 ± 6.96, p < 0.001).The discrimination abilities of the risk score model with and without biomarker showed minimal improvement (C index of 0.734 for MAGGIC risk score and 0.736 for MAGGIC risk score plus BNP or NT-proBNP, p = 0.0502) and the calibration was found good. However, we achieved a significant improvement in net reclassification and integrated discrimination for mortality (NRI of 33.4%,p < 0.0001 and IDI of 0.002, p < 0.0001). In the KorAHF, the MAGGIC project HF risk score performed well in a large nationwide contemporary external validation cohort. Furthermore, the addition of BNP or NT-proBNPto the MAGGIC risk score was beneficial in predicting more death in hospitalized patients with HF.
Thermotropic liquid crystalline copolyester fibers according to various heat treatment conditions
Thermotropic liquid crystal copolyester (TLCP) was synthesized using a melt polymerization method, with a molar ratio composition of 2,5-diethoxy terephthalic acid (ETA), hydroquinone (HQ), and p -hydroxybenzoic acid (HBA) of 1:1:3. TLCP exhibited nematic liquid crystalline mesophase and maintained nematic textures under all heat treatment conditions applied. The synthesized TLCP was processed into fibers using a capillary rheometer. The liquid crystalline mesophase, thermo-mechanical properties, and morphology of TLCP fibers obtained under various heat treatment conditions were investigated. The thermo-mechanical properties of the heat-treated fibers were improved compared to those of the as-spun fibers. The best results were obtained for TLCP fibers annealed at 230 °C for 9 h. The heat-treated fibers showed a well-developed microfiber morphology compared to the as-spun fibers. In the spun fibers, a skin–core morphology was observed regardless of the heat treatment conditions, and a well-developed fiber morphology better than the core area was observed in the skin area. The diameter of the fiber heat-treated at 230 °C for 9 h was approximately 60–110 nm.
Sustainable and eco-friendly syntheses of green MXenes for advanced battery applications
MXenes, a versatile family of two-dimensional (2D) transition metal carbides and nitrides, have attracted significant attention for battery applications due to their exceptional properties, such as high electronic conductivity, tunable microstructure, robust mechanical and chemical stability, and compositional diversity. However, despite these advantages, conventional MXene synthesis methods-relying heavily on toxic acid etching - pose serious environmental hazards, undermining their suitability for sustainable energy applications. In this context, eco-friendly and non-toxic MXene synthesis routes have become increasingly critical for enabling the widespread adoption of MXene, driving extensive research into alternative, green synthetic approaches. These recent advances in environmentally benign synthesis are pivotal to unlocking the full potential of MXenes for diverse next-generation battery technologies. In this review, we provide a comprehensive overview of green and sustainable MXene synthesis strategies, highlighting the latest developments that go beyond traditional fluorine-based routes. Each synthetic process is comparatively analyzed with respect to its efficacy, limitations, and implications for practical application as key functional components in lithium-ion batteries (LIBs) and post-LIB systems. Finally, we offer a perspective on how the development of eco-friendly MXenes can contribute to overcoming the industrial challenges facing advanced battery technologies. Graphical Abstract