• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.6
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• pp.391-398
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• 2023

In this paper, a penalized maximum likelihood estimation (PMLE) method that applies a penalty to increase the accuracy of a basis-screening-based Kriging model (BSKM) is introduced. The maximum order and set of basis functions used in the BSKM are determined according to their importance. In this regard, the cross-validation error (CVE) for the basis functions is employed as an indicator of importance. When constructing the Kriging model (KM), the maximum order of basis functions is determined, the importance of each basis function is evaluated according to the corresponding maximum order, and finally the optimal set of basis functions is determined. This optimal set is created by adding basis functions one by one in order of importance until the CVE of the KM is minimized. In this process, the KM must be generated repeatedly. Simultaneously, hyper-parameters representing correlations between datasets must be calculated through the maximum likelihood evaluation method. Given that the optimal set of basis functions depends on such hyper-parameters, it has a significant impact on the accuracy of the KM. The PMLE method is applied to accurately calculate hyper-parameters. It was confirmed that the accuracy of a BSKM can be improved by applying it to Branin-Hoo problem.

• Information Systems Review
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• v.25 no.1
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• pp.213-231
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• 2023

With the rapid development of live streaming commerce, online host as an information source plays a critical role in affecting live streaming performance. However, the impact of different product types on the relationship between online hosts and live streaming has been less studied. Based on the elaboration likelihood model (ELM) and information source theory, this study aims to empirically investigate what factors influence the sales of live streaming commerce and how product type moderates the relationship between them. The analysis of 11,422 live streaming commerce data collected for four months from October 10, 2021 to February 10, 2022 shows that, among the factors related to source credibility and attractiveness, multi-channel networks (MCN) and the number of followers positively affect the sales volume of live streaming commerce, whereas the reputation score harms the sales. Moreover, the moderating effect of the product type (i.e., ratio of involvement products) on the relationships is confirmed. The findings enrich the literature on live streaming commerce performance. The limitations and future research directions are also discussed.

• Environmental and Resource Economics Review
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• v.13 no.2
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• pp.175-194
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• 2004

Volumes of research have been implemented to estimate and predict the oil price. These models, however, fail in accurately predicting oil price as a model composed of only a few observable variables is limiting. Unobservable variables and news that have been overlooked in past research, yet have a high likelihood of affecting the oil price. Hence, this paper analyses the news impact on the price. The standard GARCH model fails in capturing some important features of the data. The estimated news impact curve for the GARCH model, which imposes symmetry on the conditional variances, suggests that the conditional variance is underestimated for negative shocks and overestimated for positive shocks. Hence, this paper introduces the asymmetric or leverage volatility models, in which good news and bad news have different impact on volatility. They include the EGARCH, AGARCH, and GJR models. The empirical results showed that negative shocks introduced more volatility than positive shocks. Overall, the AGARCH and GJR were the best at capturing this asymmetric effect. Furthermore, the GJR model successfully revealed the shape of the news impact curve and was a useful approach to modeling conditional heteroscedasticity.

• Asian Journal of Innovation and Policy
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• v.4 no.3
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• pp.397-409
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• 2015

Nowadays, crowdfunding presents a promising development. This research focuses on the influence of platform strategy and market response on the success of crowdfunding from the perspective of the elaboration likelihood model (ELM) theory. Detailed product specifications, crowdfunding difficulty coefficient, vivid advertising video such as introduction and music, and recommendations from relevant figures are all used to depict platform strategy. Meanwhile, we use the number of lovers, followers, comments and 1 RMB backers to measure the level of market response. And thus, we model the impact of platform strategy and market response on crowdfunding success with empirical studies based on 400 samples of observed value. We found firstly that there exist significant positive relations between the total amount of funds pledged and detailed product specification, vivid advertising video, recommendations from relevant figures and the number of 1 RMB backers. Secondly, the crowdfunding difficulty of projects affects negatively, and significantly, the total amount of funds pledged. Thirdly, the influence of the number of lovers and followers on funds pledged is not significant.

• Safety and Health at Work
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• v.15 no.2
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• pp.200-207
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• 2024

Background: Workers are often exposed to hazardous heat due to their work environment, leading to various injuries. As a result of climate change, heat-related injuries (HRIs) are becoming more problematic. This study aims to identify critical contributing factors to the severity of occupational HRIs. Methods: This study analyzed historical injury reports from the Occupational Safety and Health Administration (OSHA). Contributing factors to the severity of HRIs were identified using text mining and model-free machine learning methods. The Multinomial Logit Model (MNL) was applied to explore the relationship between impact factors and the severity of HRIs. Results: The results indicated a higher risk of fatal HRIs among middle-aged, older, and male workers, particularly in the construction, service, manufacturing, and agriculture industries. In addition, a higher heat index, collapses, heart attacks, and fall accidents increased the severity of HRIs, while symptoms such as dehydration, dizziness, cramps, faintness, and vomiting reduced the likelihood of fatal HRIs. Conclusions: The severity of HRIs was significantly influenced by factors like workers' age, gender, industry type, heat index , symptoms, and secondary injuries. The findings underscore the need for tailored preventive strategies and training across different worker groups to mitigate HRIs risks.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1266-1276
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• 2021

The mask parameters of a coded aperture are critical design features when optimizing the performance of a gamma-ray camera. In this paper, experiments and Monte Carlo simulations were performed to derive the minimum detectable activity (MDA) when one seeks a real-time imaging capability. First, the impact of the thickness of the modified uniformly redundant array (MURA) mask on the image quality is quantified, and the imaging of point, line, and surface radiation sources is demonstrated using both cross-correlation (CC) and maximum likelihood expectation maximization (MLEM) methods. Second, the minimum detectable activity is also derived for real-time imaging by altering the factors used in the image quality assessment, consisting of the peak-to-noise ratio (PSNR), the normalized mean square error (NMSE), the spatial resolution (full width at half maximum; FWHM), and the structural similarity (SSIM), all evaluated as a function of energy and mask thickness. Sufficiently sharp images were reconstructed when the mask thickness was approximately 2 cm for a source energy between 30 keV and 1.5 MeV and the minimum detectable activity for real-time imaging was 23.7 MBq at 1 m distance for a 1 s collection time.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.6
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• pp.69-79
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• 2022

The purpose of the study is to look into the likelihood of private sector enterprises going bankrupt due to COVID-19 pandemic-related issues. The data for this study was taken from the World Bank's Enterprise Survey, which was intended to assess the impact of the COVID-19 pandemic on the business sector. This study uses the Ordinal Logit Method to analyze the model with dependent variables having ordinal values. The determinants reflect business performance, innovation, business relationships, and government support. According to the estimation results, a lower probability of business closures, illiquidity, and payment delays are found in businesses that maintain sales growth, operating hours, temporary workers, product portfolio, consumer demand, and input supply. Meanwhile, the increase in online business activities and receiving support from financial institutions and the government do not help businesses reduce the risk. Moreover, higher survival is found in manufacturing and developing countries. This implies the fragility of businesses in the retail and service sectors, especially for mega-enterprises in developed countries. In addition, the negative impact of the COVID-19 pandemic on businesses in Europe and West Asia is less severe than in other regions. The results imply policies to support the private sector during the pandemic, such as increasing labor market flexibility or rapidly implementing supportive policies.

• Journal of Korean Society for Quality Management
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• v.46 no.3
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• pp.441-452
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• 2018

Purpose: The purpose of this paper is to study quantitative risk grade assessment for objective government quality assurance activities based on risk management in initial mass production for weapon systems. Methods: The Defense quality management regulations and foreign risk assessment documents are referred to analyze problems performing quality assurance actives. The failure rate data, maintainability and cost of products have been studied to quantify the risk Likelihood and impact. The analyzed data were classified as risk grade assessment through K-means Cluster Analysis method. Results: Results show that a proposed method can objectively evaluate risk grade. The analyzed results are clustered into three levels such as high, middle and low. Two products are allocated high, eleven low and seven middle. Conclusion: In this paper, quantitative risk grade assessment methods were presented by analyzing risk ratings based on objective data. The findings showed that the methods would be effective for initial mass production for weapon systems.

• Korean Journal of Child Studies
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• v.34 no.5
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• pp.127-144
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• 2013

The purpose of this study was (1) to examine the impact of chronic diseases on adolescent's peer relationships, and (2) to investigate the mediating effect of self-perceived health status and resilience on the relationship between their physical health states and peer relationships. The authors used the first-wave panel data from 'the Korean Children-Youth Panel Survey'. The sample included 2,351 first-grade of middle school students(boys 50.1%, girls 49.9%). Among the subjects examined 48.11% had chronic diseases. Using maximum likelihood estimation with Amos18(Arbuckle, 2009), SEM software, structural equation modeling was tested. The major findings were as follows : 1. Adolescents' chronic diseases had a negative impact on peer relationships. 2. Self-perceived health status and resilience had a mediating effect. This suggests that self-perceived health status and resilience could be protective factors when it comes to perceive peer relationships more positively for adolescents with chronic diseases. 3. Resilience was directly affected by self-perceived health status. This indicates that positive self-perception about their health status encourages adolescents with chronic diseases to be more resilient and to more positively affect their perception of their relationships with peers.

• The Journal of Industrial Distribution & Business
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• v.14 no.1
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• pp.49-56
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• 2023

Purpose: This research aims to explore the impact of fashion marketing on the sales of luxury brand items and to identify the strategies that can be used to market luxury fashion items successfully, addressing the research gap of how fashion marketing can lead to increased sales, customer loyalty, and satisfaction for luxury brand items. Research design, data and methodology: The present study conducted the method of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) which is a reporting guideline for methodical assessments and meta-analyses. It offers a consistent approach for conducting and reporting these types of studies, which can help to improve their quality and transparency. Results: The findings indicated that fashion marketing can positively impact luxury brand sales. It can significantly increase the number of luxury brand purchases. the presence of the quality label increased the participants' purchase intention and attitude towards the brand, suggesting that the quality label can create a positive perception of the brand and increase the likelihood of purchasing. Conclusions: This research concludes that fashion marketing can have a positive effect on improved customer recognition of the brand. Thus, companies should focus on developing campaigns that capture the attention of potential consumers, creating an emotional connection with them.