• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.489-496
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• 2019

This paper is a study on the evaluation of loss factor of damping treatment materials to reduce the noise and vibration for panels of railway vehicles and automobiles. In order to determine the modal parameters of damping materials, beam excitation tests were carried out using different type PVC coated aluminum and steel base beam specimens. The specimens were excited from 10 Hz to 1000 Hz frequency range using sinusoidal force, and transfer mobility data were measured by using an accelerometer. The loss factors were determined by using integrated program, based on theories of Half Power Method, Minimum Tangent Error Method, Minimum Angle Error Method and Phase Change Method, which enable to evaluate the parameters using modal circle fit and least squares error method. In the case of lower loss factor and data of linear characteristics, any method could be applied for evaluation of parameters, however the case of higher loss factor or data including non-linear characteristics, the minimum angle error method could reduce the loss factor evaluation. The obtained dynamic properties of the coating material could be used for application of Finite Element Method analyzing the noise control effects of complex structures such as carbody or under-floor boxes of rolling stock. The damping material will be very useful to control the structural noise, because the obtained modal loss factors of each mode show very good effect on over $2^{nd}$ mode frequency range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.638-643
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• 2021

Oil is used in various industries, including the agricultural sector, food industry, and functional cosmetics. These oils are chemically unstable and prone to oxidation when exposed to oxygen, light, moisture, or high temperatures. Therefore, various attempts have been made to encapsulate them so that they are not exposed to such environments. When oil is injected into a refrigerant with greater density, the oil can be encapsulated as it rises due to buoyancy caused by the density difference. In this study, oil encapsulation was simulated to find the optimal conditions for operating equipment using computational fluid dynamics (CFD) for multiphase flows. Water or serum can be used as a refrigerant. The viscosity of water is relatively small, and if it is used as a refrigerant, oil droplets can be produced well even if oil and water are continuously injected in the equipment. However, the viscosity of serum is very high, and if it is used, the oil is stretched out and does not leave the nozzle. The results show that when using serum as a cooling medium, oil encapsulation is possible if the injection is stopped for some time after instantaneous injection at high speed.

• Communications of Mathematical Education
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• v.35 no.2
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• pp.153-172
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• 2021

Various competencies such as critical thinking, systems thinking, problem solving competence, communication skill, and data literacy are likely to be required in the 4th industrial revolution. The competency regarding data literacy is one of those competencies. To nurture citizens who will live in the future, it is timely to consider research on teacher education for supporting teachers' development of statistical thinking as well as statistical knowledge. Therefore, in this study we developed and implemented a data analysis project for pre-service teachers to understand their changes in statistical knowledge in addition to their experiences of data-driven decision making process that required them utilizing their statistical thinking. We used a mixed method (i.e., sequential explanatory design) research to analyze the quantitative and qualitative data collected. The findings indicated that pre-service teachers have low knowledge level of their understanding on the relationship between population means and sample means, and estimation of the population mean and its interpretation. When it comes to the data-driven decision making process, we found that the pre-service teachers' experiences varied even when they worked as a small group for the project. We end this paper by presenting implications of the study for the fields of teacher education and statistics education.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.2
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• pp.1-7
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• 2021

The concrete deck slab at the continuous span support of the steel box girder bridge is a structure that is combined with the upper flange. It is a structure that can cause tension cracks in the deck slab at the support causing problems such as durability degradation in long span bridges. This is because the tensile stress in the longitudinal direction of the slab exceeds the design tensile strength due to the effects of dead load and live load when applying a long span. Accordingly, it is necessary to control tensile cracking by adding a reinforcing bar in the axial direction to the slab at the support and to introduce additional compressive stress. To solve this problem, a structural system of a steel box girder bridge was proposed that introduces compressive stress as PS steel wire tension in the tensile stress section of the upper slab in the continuous support. The resulting structural performance was compared and verified through the finite element analysis and the steel wire tension test of the actual specimen. By introducing compressive stress that can control the tensile stress and cracking of the slab generated in the negative moment through the tension of the PS steel wire, it is possible to improve structural safety and strengthen durability compared to the existing steel box girder bridge.

• Land and Housing Review
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• v.13 no.1
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• pp.55-65
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• 2022

This paper investigates the distinct characteristics of freehold and leasehold households living in the seven largest cities and the other areas. We employ the two-stage logit regression analysis to identify the marginal effects of wealth and income after controlling for the other one. We document the following results. First, households with more net wealth are more likely to reside in their own houses, regardless of living areas. Second, the pure income effect after controlling for wealth and other variables lowers the tendency of freeholders to live in the seven largest cities while increasing the tendency to live in the other areas. Furthermore, the income effects reduce the tendency to live in the former regions. Our results suggest that the pure income effects enhance preferences for a better living environment (e.g., larger spaces, better school districts, etc.), whereas the wealth effect increases the likelihood of freeholds.

• The Korean Society of Law and Medicine
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• v.23 no.2
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• pp.3-36
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• 2022

In order to solve the pharmaceutical kickback problem, it is needed to establish legal system that allow ways to enable pharmaceutical promotion of medicines without kickbacks as well as provide sanction those who commit illegal act. Before the National Assembly and the government focused on strengthening sanctions. As a result, in 2014, a system of suspending medical care benefits was introduced, which could inflict heavy losses on pharmaceutical companies by withdrawing target medicines from the market. However, three years after the introduction, the system was abolished in 2018, recognizing the problem that the disposition could infringe on the patients' right to access to and choice of medicines. In 2021, the National Assembly made it possible for dispositions suspending medical care benefits regarding the third violation, which remained symbolic until then, replaced with administrative fines. Although the legislator's reflective stance on the system is more than clear, the Ministry of Health and Welfare still interprets that the old law should be applied to kickbacks for the period of the law. Moreover, regarding the substitution of fines at the discretion of the Minister of Health and Welfare under the old law, the narrow standards taken under the old law seems to be maintained. In this paper, firstly pharmaceutical kickback issue, the main reason for the introduction of the system, will be explained, after that the history of introduction and abolition of the system examined and last but not least the unconstitutionality of the system and the illegality of the disposition are to be examined.

• Journal of the Korean Society of Earth Science Education
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• v.15 no.2
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• pp.263-272
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• 2022

The purpose of this study is to investigate the effect of developing and applying a program in the field of astronomy that can improve the spatial perception ability and task commitment of elementary science gifted students. The subjects of this study were 22 students in the advanced course in the elementary science gifted class affiliated with the Gifted and Talented Center of University B. In order to improve spatial perception ability and task attachment to students in elementary school science gifted class, a total of 12 educational learning programs were developed and applied. The results of this study were interpreted as quantitative analysis. The results of this study are as follows. First, the astronomy class had a positive effect on the spatial perception ability improvement of elementary science gifted students. Second, the astronomy class had a positive effect on improving the task commitment of elementary school science gifted students. Third, astronomy class of elementary school science gifted students was more effective in improving spatial perception than improving task commitment. Since elementary school science gifted students are selected with excellent intelligence, creativity, and task commitment, an Individualized Education Program (IEP) is developed and applied to better express their potential giftedness. In addition, in order to express more in-depth giftedness in gifted education, it is necessary to pay attention to the development of programs that can express individual gifted characteristics.

• Journal of the Korean Geotechnical Society
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• v.39 no.10
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• pp.41-48
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• 2023

The presence of abnormalities in the subgrade of roads poses safety risks to users and results in significant maintenance costs. In this study, we aimed to experimentally evaluate the temperature distributions in abnormal areas of subgrade materials using infrared cameras and analyze the data with machine learning techniques. The experimental site was configured as a cubic shape measuring 50 cm in width, length, and depth, with abnormal areas designated for water and air. Concrete blocks covered the upper part of the site to simulate the pavement layer. Temperature distribution was monitored over 23 h, from 4 PM to 3 PM the following day, resulting in image data and numerical temperature values extracted from the middle of the abnormal area. The temperature difference between the maximum and minimum values measured 34.8℃ for water, 34.2℃ for air, and 28.6℃ for the original subgrade. To classify conditions in the measured images, we employed the image analysis method of a convolutional neural network (CNN), utilizing ResNet-101 and SqueezeNet networks. The classification accuracies of ResNet-101 for water, air, and the original subgrade were 70%, 50%, and 80%, respectively. SqueezeNet achieved classification accuracies of 60% for water, 30% for air, and 70% for the original subgrade. This study highlights the effectiveness of CNN algorithms in analyzing subgrade properties and predicting subsurface conditions.

• Korean Journal of Clinical Laboratory Science
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• v.55 no.4
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• pp.235-243
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• 2023

As next-generation sequencing has been developed and used widely, RNA-sequencing (RNA-seq) has rapidly emerged as the first choice of tools to validate global transcriptome profiling. With the significant advances in RNA-seq, various types of RNA-seq have evolved in conjunction with the progress in bioinformatic tools. On the other hand, it is difficult to interpret the complex data underlying the biological meaning without a general understanding of the types of RNA-seq and bioinformatic approaches. In this regard, this paper discusses the two main sections of RNA-seq. First, two major variants of RNA-seq are described and compared with the standard RNA-seq. This provides insights into which RNA-seq method is most appropriate for their research. Second, the most widely used RNA-seq data analyses are discussed: (1) exploratory data analysis and (2) pathway enrichment analysis. This paper introduces the most widely used exploratory data analysis for RNA-seq, such as principal component analysis, heatmap, and volcano plot, which can provide the overall trends in the dataset. The pathway enrichment analysis section introduces three generations of pathway enrichment analysis and how they generate enriched pathways with the RNA-seq dataset.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.16-22
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• 2024

Polymer electrolyte membrane fuel cells have the advantage of low operating temperatures and fast startup and response characteristics compared to others. Simulation studies are actively researched because their cost and time benefits. In this study, the resistance of water residual in the gas diffusion layer (GDL) of the unit cell was added to the existing equation to compare the actual data with the model data. The experiments were conducted with a 25 cm² unit cell, and the samples were separated into stopping times of 0, 10, and 60 minutes following primary impedance measurement, activation, and polarization curve data acquisition. This gives 0, 10, and 60 minutes for the residual water in the GDL to evaporate. Without the rest period, the magnitude of the performance improvement was not significantly different at the same potential and flow rate, but the rest period did improve the performance of the membrane electrode assembly when measuring impedance. By changing the magnitude of the resistance reduction to an overvoltage, the voltage difference between the fuel cell model with and without residual water was compared, and the error rate in the high current density region, which is dominated by concentration losses, was reduced.