• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.4
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• pp.267-274
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• 2024

Hydrogen embrittlement fracture poses a challenge in ensuring the structural integrity of materials exposed to hydrogen-rich environments. This study advances our comprehension of hydrogen-induced fracture through an integrated numerical modeling approach. In addition, it employs a ductile fracture model named the Gurson-cohesive model (GCM) and hydrogen diffusion analysis. GCM is employed as a fracture model that combines the Gurson model to illustrate the continuum damage evolution and the cohesive zone model to describe crack surface discontinuity and softening behavior. Moreover, porosity and stress triaxiality are considered as crack initiation criteria . A hydrogen diffusion analysis is also integrated with the GCM to account for hydrogen enhanced decohesion (HEDE) mechanisms and their subsequent impacts on crack initiation and propagation. This framework considers the influence of hydrogen on the softening behavior of the traction-separation relationship on the discontinuous crack surface. Parametric studies explore the sensitivity to diffusion properties and hydrogen-induced fracture properties. By combining numerical models of hydrogen diffusion and the ductile fracture model, this study provides an understanding of hydrogen-induced fracture and thereby contributes significantly to the ongoing efforts to design materials that are resilient to hydrogen embrittlement in practical engineering applications.

• Journal of the Korean Geotechnical Society
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• v.40 no.4
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• pp.91-103
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• 2024

In this study, we propose an outlier detection method that considers the spatial distribution of intelligent compaction measurement values (ICMVs) to address the high variability of ICMVs measured continuously across an entire construction area. The proposed method initially identified cases where the CMV at a specific location decreased despite an increase in the number of compaction passes. Among these, values that significantly differed from those measured within a 1.5-m radius were classified as outliers. Applying this method to CMV data obtained from field tests, we found that it effectively excluded the influence of changes in roller operating conditions unrelated to compaction quality while considering the inherent heterogeneity of the soil. However, after removing the outliers, the coefficient of variation of CMV (21.4%-26.3%) remained higher than the 20% suggested by relevant standards. Further field tests are needed to modify the proposed outlier detection method and to establish reasonable criteria for the variability of ICMV.

• Journal of the Korean Geotechnical Society
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• v.40 no.4
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• pp.33-47
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• 2024

Offshore wind structures are subject to long-term repeated horizontal loads from wind, waves, and currents, making it essential to consider these loads in the design of offshore foundations. In this respect, monopiles are large-diameter hollow steel pipes that are relatively simple to construct compared with piles used on onshore sites. They can provide stable support for wind structures and have well-established design codes, leading to their widespread use globally. The behavior of monopiles under lateral static loads is typically assessed using the p-y method proposed by the American Petroleum Institute (API). However, the applicability of p-y curves to large-diameter monopiles exposed to repeated cyclic horizontal loads, such as those experienced in offshore wind applications, must yet be evaluated. Thus, this study evaluated the behavior of monopiles under two-way cyclic horizontal loads in loose silty sand, a representative soil type of the southwestern coast of Korea, using centrifuge model tests. The results demostrated that the behavior of monopiles varied depending on the loading level, number of cycles, and direction of the cyclic loads. Furthermore, the p-y curve method proposed by the API overestimated the behavior of a large-diameter monopile installed in silty sand under two-way cyclic loads.

• Journal of the Korean Geotechnical Society
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• v.40 no.4
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• pp.69-79
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• 2024

Field geotechnical data are obtained from various field and laboratory tests and are documented in geotechnical investigation reports. For efficient design and construction, digitizing these geotechnical parameters is essential. However, current practices involve manual data entry, which is time-consuming, labor-intensive, and prone to errors. Thus, this study proposes an automatic data extraction method from geotechnical investigation reports using image-based deep learning models and text-mining techniques. A deep-learning-based page classification model and a text-searching algorithm were employed to classify geotechnical investigation report pages with 100% accuracy. Computer vision algorithms were utilized to identify valid data regions within report pages, and text analysis was used to match and extract the corresponding geotechnical data. The proposed model was validated using a dataset of 205 geotechnical investigation reports, achieving an average data extraction accuracy of 93.0%. Finally, a user-interface-based program was developed to enhance the practical application of the extraction model. It allowed users to upload PDF files of geotechnical investigation reports, automatically analyze these reports, and extract and edit data. This approach is expected to improve the efficiency and accuracy of digitizing geotechnical investigation reports and building geotechnical databases.

• Journal of the Institute of Convergence Signal Processing
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• v.25 no.2
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• pp.94-99
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• 2024

Recently, wind power has been gaining attention as a highly efficient renewable energy source, leading to various technological developments worldwide. Typically, wind power is operated in the form of large wind farms with many wind turbines installed in areas rich in wind resources. However, in developing countries or regions isolated from the power grid, off-grid small wind power systems are emerging as an efficient solution. To efficiently operate and expand off-grid small-scale power systems, the development of real-time monitoring systems is required. For the efficient operation of small wind power systems, it is essential to develop real-time monitoring systems that can actively respond to excessive wind speeds and various environmental factors, as well as ensure the stable supply of produced power to small areas or facilities through an Energy Storage System (ESS). The implemented system monitors turbine RPM, power generation, brake operation, and more to create an optimal operating environment. The developed small wind power system can be utilized in remote road lighting, marine leisure facilities, mobile communication base stations, and other applications, contributing to the development of the RE100 industry ecosystem.

• Journal of the Institute of Convergence Signal Processing
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• v.25 no.2
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• pp.113-118
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• 2024

Recently, advancements in artificial intelligence and computer graphics technology have led to the emergence of various virtual humans across multiple media such as movies, advertisements, broadcasts, games, and social networking services (SNS). In particular, in the advertising marketing sector centered around virtual influencers, virtual humans have already proven to be an important promotional tool for businesses in terms of time and cost efficiency. In Korea, the virtual influencer market is in its nascent stage, and both large corporations and startups are preparing to launch new services related to virtual influencers without clear boundaries. However, due to the lack of public disclosure of the development process, they face the situation of having to incur significant expenses. To address these requirements and challenges faced by businesses, this paper implements a photogrammetry-based facial capture system for creating realistic virtual humans and explores the use of these models and their application cases. The paper also examines an optimal workflow in terms of cost and quality through MetaHuman modeling based on Unreal Engine, which simplifies the complex CG work steps from facial capture to the actual animation process. Additionally, the paper introduces cases where virtual humans have been utilized in SNS marketing, such as on Instagram, and demonstrates the performance of the proposed workflow by comparing it with traditional CG work through an Unreal Engine-based workflow.

• Journal of Christian Education in Korea
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• v.78
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• pp.213-229
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• 2024

Purpose of Study : The purpose of this study is to verify whether self-control has a mediating effect on the influence of grit on college students' self-efficacy, which has a significant impact on academic achievement. Research content and methods : In order to verify the influence of grit and self-control on college students' self-efficacy, this study first selected measurement tools for self-efficacy, grit, and self-control and created an online questionnaire. Next, a survey was conducted on 128 students at University A in Chungcheongnam-do. Descriptive statistical analysis and bivariate correlation analysis were performed on the collected data to verify the normality of the data and multicollinearity between factors. In addition, multiple regression analysis was used to verify the influence of grit and self-control on self-efficacy. Next, the effect of grit on self-efficacy was analyzed using structural equation modeling to verify whether self-control mediates it. As a result of the analysis, overall self-efficacy was influenced by the reliability of self-control and academic passion of grit. Self-confidence, a sub-factor of self-efficacy, was influenced by reliability of self-control and academic passion of grit. Self-regulation efficacy was influenced by the reliability of self-control and academic persistence of grit. Preference for task difficulty was influenced by grit, maintenance of academic interest, and self-control. Next, self-control was found to mediate the effect of grit on self-efficacy. Conclusion and Recommendations : This study explored the effects of grit and self-control on college students' self-efficacy. As a result, grit and self-control had a positive effect on self-efficacy. Additionally, self-control was found to mediate the effect of grit on self-efficacy. This study proposes to support grit and self-control in order to support successful academic achievement of college students.

• Journal of Family Resource Management and Policy Review
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• v.28 no.3
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• pp.17-27
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• 2024

The purpose of this study is to investigate the impact of discrimination experienced by single-parent household heads and their children on their level of depression. As its sample, the study used data from 1,631 relevant respondents to the 2021 Single-Parent Family Status Survey conducted by the Ministry of Gender Equality and Family. The collected data were analyzed using IBM SPSS, version 25.0, including descriptive statistics, difference verification, correlations, and regression analysis. First, general characteristics were classified as single-parent and family characteristics, health factors, and economic resources, and differences in depression were analyzed accordingly. Among the health factors, health status, frequency of exercise, and methods of alleviating depression were significant. Regarding economic resources, housing type and monthly household income were significant factors. Second, factors influencing the impact of discrimination experiences on depression were analyzed. The results indicated that among health factors, health status was significant. With regard to economic resources, monthly household income, discrimination experiences of household heads, discrimination experienced by children, and overall discrimination experiences were significant. No significant variables were identified among single-parent and family characteristic factors. Therefore, it was evident that health factors and economic resources, as well as discrimination experiences, are important variables that increase depression in single-parent household heads. Based on these findings, corresponding relevant alternatives were suggested.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.3
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• pp.179-188
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• 2024

To enhance the predictability of aesthetic treatment outcomes in aesthetic prosthetic restorations, considerations must include analysis of facial features, the relationship between teeth and lips, proportions of tooth width/length, gingival form, and more. Traditional diagnostic wax-ups have limitations in considering the patient's facial features and are unable to facilitate rapid form modifications. With recent advancements in digital technology, it is now possible to digitize the patient's facial features in three dimensions, enabling the design of restorations that harmonize with facial features. These digital workflows not only improve efficiency but also provide patients with faster visualization of treatment outcomes, thereby enhancing motivation. Therefore, in this case, a treatment plan is devised to utilize digital diagnostic wax-ups considering the patient's facial features for the final prosthetic design.

• Journal of Navigation and Port Research
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• v.48 no.4
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• pp.335-341
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• 2024

Recently, research, development, and commercialization of maritime autonomous surface ships (MASS) and remote control are in progress. Remote control is intended to secure autonomous navigation environments for existing ships or early-stage MASS using a remote control system (RCS). The main function of an RCS is to control MASS using data transmission between the MASS and the remote control centre. Remote control by a remote control officer also has an important function. The purpose of this study was to develop RCS and a performance evaluation technique for operation data provided by the RCS. The experiment was conducted during the navigation period of a training ship 'Hannara' after building experimental equipment at both an onshore remote control center and a training ship. As a result of evaluating data transmitted and received using the developed RCS, it was confirmed that data transmission was possible within an error range of 0.1%p. Fourteen types of ship information reflecting the navigation environment of the training ship were confirmed to be transmitted and received. The RCS developed in this work complies with the three principles of remote control: safety, reliability, and availability. This study provides a core technology for the development of RCSs for MASS and the evaluation of data transmission performance.