• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.124-130
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• 2023

Recently, fan out wafer level packaging, which enables high integration, miniaturization, and low cost, is being rapidly applied in the semiconductor industry. In particular, FOWLP is attracting attention in the mobile and Internet of Things fields, and is recognized as a core technology that will lead to technological advancements such as 5G, self-driving cars, and artificial intelligence in the future. However, as chip density and package size within the package increase, FOWLP warpage is emerging as a major problem. These problems have a direct impact on the reliability and electrical performance of semiconductor products, and in particular, cause defects such as vacuum leakage in the manufacturing process or lack of focus in the photolithography process, so technical demands for solving them are increasing. In this paper, warpage simulation according to the thickness of FOWLP material was performed using finite element analysis. The thickness range was based on the history of similar packages, and as a factor causing warpage, the curing temperature of the materials undergoing the curing process was applied and the difference in deformation due to the difference in thermal expansion coefficient between materials was used. At this time, the stacking order was reflected to reproduce warpage behavior similar to reality. After performing finite element analysis, the influence of each variable on causing warpage was defined, and based on this, it was confirmed that warpage was controlled as intended through design modifications.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.6
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• pp.267-272
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• 2022

Online exams are not limited by time and space. It has the advantage that it does not require a separate exam site for examinees, and there is no time and cost required to move to the exam site. However, the online exam has the disadvantage that various cheating is possible because the exam is conducted in an individual environment. In addition, there is a difficulty in detecting cheating due to the lack of exam supervision methods. In addition, since the exam process and result data exist only as digital data, it is inconvenient to check directly on the server where the exam result is stored in order to check whether the exam result is forged or not. If the data related to the exam is maliciously changed, the authenticity cannot be verified. In this study, we tried to increase the reliability of the online exam by developing a blockchain-based online exam cheating detection system that stores exam progress-related data in the blockchain to detect cheating. Through the experiment, it was confirmed that forgery and falsification are detected as a result of the exam.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.57-66
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• 2023

Asset valuation of social infrastructure is essential for rational decision-making for efficient management of assets. In addition, it can be an indicator for correctly recognizing assets. In general, Korea applies depreciated replacement cost based on the straight-line method to evaluate asset value, yet this is unsuitable for evaluating actual value because it is depreciated at a constant rate over the useful life period. In order to evaluate the asset value considering the performance of the bridge, the performance index of the bridge is estimated using the Weibull distribution. Using the estimated performance indicators and defect index, a new asset value evaluation method is proposed and compared and analyzed with the existing method. The proposed valuation method can take into account the performance of the bridge, so it is judged to be more objective and reasonable than existing method.

• Geomechanics and Engineering
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• v.35 no.6
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• pp.647-663
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• 2023

The investigation of the disc cutter wear prediction has an important guiding role in TBM equipment selection, project planning, and cost forecasting, especially when tunneling in a long-distance rock formations with high strength and high abrasivity. In this study, a comprehensive database of disc cutter wear data, geological properties, and tunneling parameters is obtained from a 1326 m excavated metro tunnel project in leptynite in Shenzhen, China. The failure forms and wear consumption of disc cutters on site are analyzed with emphasis. The results showed that 81% of disc cutters fail due to uniform wear, and other cutters are replaced owing to abnormal wear, especially flat wear of the cutter rings. In addition, it is found that there is a reasonable direct proportional relationship between the uniform wear rate (WR) and the installation radius (R), and the coefficient depends on geological characteristics and tunneling parameters. Thus, a preliminary prediction formula of the uniform wear rate, based on the installation radius of the cutterhead, was established. The correlation between some important geological properties (K_V and UCS) along with some tunneling parameters (F_n and p) and wear rate was discussed using regression analysis methods, and several prediction models for uniform wear rate were developed. Compared with a single variable, the multivariable model shows better prediction ability, and 89% of WR can be accurately estimated. The prediction model has reliability and provides a practical tool for wear prediction of disc cutter under similar hard rock projects with similar geological conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.117-124
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• 2024

The objective of Value Engineering (VE) is to derive the optimal value at the most efficient life cycle cost, comprising three stages: Pre-Study, Study, and Post-Study. In this study, we propose a method for information collection and analysis during planned site visit surveys in the preparation stage of VE. The 3D spatial model, created using a drone, facilitated observation and analysis of the study area from various angles, both from the center and the outside. Additionally, through the utilization of drones, we conducted on-site investigations of the research area's 3D spatial model, enabling a macroscopic perspective previously only feasible through a microscopic viewpoint during planned site visits in the pre-study phase. Furthermore, the utilization of actual spatial data obtained from observations allowed for real-time information verification during Design VE workshops, enhancing the efficiency and reliability of the VE project.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.223-229
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• 2024

Laser-induced plasmonic sintering of metal nanoparticles (NPs) holds significant promise as a technology for producing flexible conducting electrodes. This method offers immediate, straightforward, and scalable manufacturing approaches, eliminating the need for expensive facilities and intricate processes. Nevertheless, the metal NPs come at a high cost due to the intricate synthesis procedures required to ensure long-term reliability in terms of chemical stability and the prevention of NP aggregation. Herein, we induced the self-generation of metal nanoparticles from Ag organometallic ink, and fabricated highly conductive electrodes on flexible substrates through laser-assisted plasmonic annealing. To demonstrate the practicality of the fabricated flexible electrode, it was configured in a mesh pattern, realizing multi-touchable flexible touch screen panel.

• Journal of the Korean Applied Science and Technology
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• v.41 no.2
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• pp.273-282
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• 2024

Park golf is establishing itself as a daily sport that the silver generation can enjoy physically and cost-free. Accordingly, we have examined the impact of park golf participants' passionate participation behavior on sports immersion and sports performance. The subjects were 243 park golf participants, and SPSS 21.0 and AMOS 18.0 were used for data processing. In addition, frequency analysis, reliability, confirmatory factor analysis, and correlation analysis were conducted. Path analysis was performed using SEM, and mediating effects were analyzed using bootstrapping. First, regarding the relationship between passionate behavior and sports immersion, harmonious passion did not affect sports immersion, and obsessive passion had a positive effect. Second, passion had a positive effect on sports performance. Third, sports immersion had a positive effect on sports performance. Fourth, sports commitment played a partial mediating role in the relationship between passion and sports performance. Therefore, if the environment of the park golf course is improved so that passion does not decrease, exercise immersion and exercise performance will improve.

• Journal of Space Technology and Applications
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• v.3 no.4
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• pp.355-372
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• 2023

As the need for low-cost, high-efficiency cubesats develops in the new space age, commercial paradigms are shifting in the private sector. This paper examines the challenges of launching and operating both domestic and foreign cubesats, and proposes practical solutions to ensure the robustness and reliability of the satellites from a practical perspective. In particular, the paper deals with checkpoints that are easy to miss, focusing on key events that can occur from the satellite deployment process through normal mode to mission mode in the operation scenario. Although the contents presented in this paper may not be technically applicable to all cubesat systems due to the different nature of each satellite bus system, they will be of some help during satellite assembly, integration and testing.

• Journal of Wellbeing Management and Applied Psychology
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• v.7 no.3
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• pp.67-72
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• 2024

This study developed a dry composite module-type deodorization facility with Twisting airflow changes and two forms (catalyst, adsorbent) within one module. Experiments were conducted to evaluate the reduction efficiency of odor substances C₈H₇N and C₉H₉N. The device combines UV oxidation using TiO₂, catalytic oxidation using MnO₂, and adsorption using A/C in five different methods. Data analysis of experimental results utilized the statistical package program Python 3.12. The program applied frequency analysis of odor removal efficiency, one-way ANOVA, and post-hoc tests, with statistical significance determined by p-value to ensure reliability and validity of the measurements. Results indicated that the highest removal efficiency of C₈H₇N and C₉H₉N was achieved by the UV+A/C method, suggesting the superior effectiveness and efficiency of the developed device. Combining multiple processes and technologies within one module enhanced odor treatment efficiency compared to using a single method. The device's modularity allows for flexibility in adapting to various sewage treatment scenarios, offering easy maintenance and cost-effective deodorization. This composite reaction module device can apply multiple technologies, such as biofilters, plasma, activated carbon filters, UV-photocatalysis, and electromagnetic-chemical systems. However, this study focused on UV-photocatalysis, catalysts, and activated carbon filters. Ultimately, the research demonstrates the practical applicability of this innovative device in real sewage treatment operations, showing excellent reduction efficiency and effectiveness by integrating UV oxidation, TiO₂ photocatalysis, MnO₂ catalytic oxidation, and A/C adsorption within a modular system.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.457-468
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• 2020

Problems arising during pile design works for plant construction, civil and architecture work are mostly come from uncertainty of geotechnical characteristics. In particular, obtaining the N-value measured through the Standard Penetration Test (SPT) is the most important data. However, it is difficult to obtain N-value by drilling investigation throughout the all target area. There are many constraints such as licensing, time, cost, equipment access and residential complaints etc. it is impossible to obtain geotechnical characteristics through drilling investigation within a short bidding period in overseas. The geotechnical characteristics at non-drilling investigation points are usually determined by the engineer's empirical judgment, which can leads to errors in pile design and quantity calculation causing construction delay and cost increase. It would be possible to overcome this problem if N-value could be predicted at the non-drilling investigation points using limited minimum drilling investigation data. This study was conducted to predicted the N-value using an Artificial Neural Network (ANN) which one of the Artificial intelligence (AI) method. An Artificial Neural Network treats a limited amount of geotechnical characteristics as a biological logic process, providing more reliable results for input variables. The purpose of this study is to predict N-value at the non-drilling investigation points through patterns which is studied by multi-layer perceptron and error back-propagation algorithms using the minimum geotechnical data. It has been reviewed the reliability of the values that predicted by AI method compared to the measured values, and we were able to confirm the high reliability as a result. To solving geotechnical uncertainty, we will perform sensitivity analysis of input variables to increase learning effect in next steps and it may need some technical update of program. We hope that our study will be helpful to design works in the future.