• The Journal of Bigdata
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• v.8 no.2
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• pp.165-175
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• 2023

LNG is a representative imported cargo at Incheon Port and has a relatively high contribution to the increase/decrease in overall cargo volume at Incheon Port. In addition, in the view point of nationwide, LNG is the one of the most important key resource to supply the gas and generate electricity. Thus, it is very essential to identify the factors that have impact on the demand fluctuation and build the appropriate forecasting model, which present the basic information to make balance between supply and demand of LNG and establish the plan for power generation. In this study, different to previous research based on macroscopic annual data, the weekly demand of LNG is converted from the cargo volume unloaded by LNG carriers. We have identified the periodicity and correlations among internal and external factors of demand variability. We have identified the input factors for predicting the LNG demand such as seasonality of weekly cargo volume, the peak power demand, and the reserved capacity of power supply. In addition, in order to predict LNG demand, considering the characteristics of the data, time series prediction with weekly LNG cargo volume as a dependent variable and prediction through an artificial neural network model were made, the suitability of the predictions was verified, and the optimal model was established through error comparison between performance and estimates.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.532-537
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• 2024

In this study, wear characteristics and microstructure changes due to changes in alloy composition of Ni-Cr-Mo-V and Ni-Cr-Mo low-alloy steels used in brake discs for transportation system such as aircraft and high-speed trains. As a result of the hardness test, the hardness of C-Mo-V steel was the highest at 39.4±0.9HRc, and the hardness of Ni-Cr-Mo steel was the lowest at 32.4±0.6HRc. The friction coefficient tended to decrease as the vertical load increased. At a vertical load of 1 N, the friction coefficient of Ni-Cr-Mo steel was the highest at 0.842, and at a vertical load of 5 N, Mn-Cr-V steel was the highest at 0.696. Ni-Cr-Mo showed the largest wear scar width, depth, and wear amount, with a width of 711 ㎛, a depth of 8.24 ㎛, and a wear amount of 11 mg under a vertical load of 1 N, and a width of 1,017 ㎛, a depth of 19.17 ㎛, and a wear amount of 17 mg under a vertical load of 5 N. As a result of wear mechanism analysis, ploughing, delamination, and adhesion in all specimens, with plastic deformation being more prominently observed in Ni-Cr-Mo.

• Food Science of Animal Resources
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• v.44 no.5
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• pp.1080-1095
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• 2024

In contemporary society, the increasing number of pet-owning households has significantly heightened interest in companion animal health, expanding the probiotics market aimed at enhancing pet well-being. Consequently, research into the gut microbiota of companion animals has gained momentum, however, ethical and societal challenges associated with experiments on intelligent and pain-sensitive animals necessitate alternative research methodologies to reduce reliance on live animal testing. To address this need, the Fermenter for Intestinal Microbiota Model (FIMM) is being investigated as an in vitro tool designed to replicate gastrointestinal conditions of living animals, offering a means to study gut microbiota while minimizing animal experimentation. The FIMM system explored interactions between intestinal microbiota and probiotics within a simulated gut environment. Two strains of commercial probiotic bacteria, Enterococcus faecium IDCC 2102 and Bifidobacterium lactis IDCC 4301, along with a newly isolated strain from domestic dogs, Lactobacillus acidophilus SLAM AK001, were introduced into the FIMM system with gut microbiota from a beagle model. Findings highlight the system's capacity to mirror and modulate the gut environment, evidenced by an increase in beneficial bacteria like Lactobacillus and Faecalibacterium and a decrease in the pathogen Clostridium. The study also verified the system's ability to facilitate accurate interactions between probiotics and commensal bacteria, demonstrated by the production of short-chain fatty acids and bacterial metabolites, including amino acids and gamma-aminobutyric acid precursors. Thus, the results advocate for FIMM as an in vitro system that authentically simulates the intestinal environment, presenting a viable alternative for examining gut microbiota and metabolites in companion animals.

• Journal of Radiation Industry
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• v.18 no.3
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• pp.167-171
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• 2024

Technetium-99 (⁹⁹Tc) is recognized as a critical concern in the disposal of spent nuclear fuel due to its long half-life and remarkable stability, existing predominantly as TcO₄^- in the natural environment. The anionic form of technetium is highly soluble and mobile, posing significant environmental risks from the viewpoint of nuclear waste management. Thus, developing efficient and cost-effective sorbents for aqueous Tc(VII) is essential for mitigating relevant contamination. In the present work, the adsorption characteristics of Re(VII), a chemical analog of Tc(VII), were investigated using the clay mineral bentonite, modified with two different organic cations: hexadecylpyridinium (HDPy) and hexadecyltrimethylammonium (HDTMA). Sorption experiments were conducted at a liquid-to-solid ratio of 1 g/L with Re(VII) solutions prepared at concentrations from 10^-4 mol/L to 10^-6 mol/L. The sorption ratio and distribution coefficients were determined with samples collected at reaction times of 10, 50, 100, and 500 minutes after 0.45 ㎛ syringe filtration. In parallel, the modified bentonite samples were further analyzed using the X-ray diffraction (XRD) method to understand the adsorption mechanism of Re(VII) onto the target minerals. According to the quantification analysis results, a rapid equilibrium reaction of aqueous Re(VII) for all modified bentonite samples was identified. Moreover, near-complete adsorption of Re(VII) was observed when the bentonite was modified at 200-400% of its cation exchange capacity (CEC) for both organic cations. For cases of lower modification, the HDTMA-modified bentonite showed relatively higher adsorption efficiency compared with the one modified with HDPy. This result was inferred to be due to the difference in inter-layer spacing based on the characteristics of the organic cations. It is expected that the results obtained through this study will serve as a preliminary case for the synthesis of adsorbents for the retardation of highly mobile anionic radionuclides, such as I and Tc, in the natural environment.

• The Journal of the Convergence on Culture Technology
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• v.10 no.4
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• pp.357-365
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• 2024

The purpose of this study is to investigate the effects of children's robot-based play on sequential thinking through appreciation of picture books. For this purpose, 15 children aged 5 years old in each kindergarten located in Seoul were selected and J kindergarten (experimental group) supported <Picture book appreciation robot play> and C kindergarten (comparison group) supported <Picture book appreciation free play>. In order to examine the difference in play experience between the two groups, the score data before and after play support was collected using the sequential thinking test tool, and the collected data were analyzed using SPSS 28.0 program to perform ANCOVA (Covariance Analysis). As a result, the experimental group that experienced robot-based play through picture book appreciation showed significant improvement in the total score of sequential thinking and the sub-areas of dynamics, behavior, and intention compared to the control group.The results of this study are valuable as a play study to discover the value of robots as a creative play medium led by young children and to promote sequential thinking ability, which is emphasized as the capacity of future society.

• Journal of Korea Foundry Society
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• v.44 no.1
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• pp.3-8
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• 2024

Reducing industrial waste and improving the atmospheric environment recently have emerged as important tasks for the casting industry. Various types of artificial sand that can replace natural sand have been developed and used to solve problems that arise with the use of conventional foundry sand and to improve the foundry environment. However, only limited physical properties provided by overseas suppliers are known and in-depth comparative analyses with existing natural sand are lacking. For the design of the casting process, a wide range of thermal properties must be secured not only at room temperature but also at high temperatures. In addition, it is important to compare and analyze the differences in thermal properties between existing natural and artificial sand because changes in thermal properties require changes in the design of the casting method. In this study, the thermal behavior of the mold was analyzed through a thermal expansion test of mold blocks for natural and artificial sand., To this end, a thermal property test to evaluate thermal conductivity was performed by determining a temperature range. The results of the experiment, revealed that the thermal conductivity was 5-40% higher in artificial sand than in natural sand, and the coefficient of thermal expansion was about 15% lower for artificial sand. However, there was not a significant difference in specific heat regardless of the composition.

• Journal of the Korea Institute of Building Construction
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• v.24 no.4
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• pp.393-402
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• 2024

The Korean Industrial Standard(KS) KS F 2527("Aggregates for Concrete") does not explicitly define criteria for clay mineral content in aggregates. This lack of clear quality standards and testing methodologies is further compounded by a scarcity of relevant research within both academic and industrial spheres. Consequently, the construction industry, encompassing both aggregate production and utilization, often overlooks the management of clay mineral content due to its perceived economic implications. This study addresses this gap by investigating the current state of regulations concerning clay mineral content in aggregates, exploring the causes of its occurrence, and evaluating its impact on concrete performance. The chemical composition of the clay minerals was determined to primarily consist of Al₂O₃, Fe₂O₃, and SiO₂, which are commonly found in clay. X-ray diffraction(XRD) analysis revealed that the predominant clay minerals were montmorillonite and illite, both known for their high absorption capacity. An examination of domestic and international standards for clay mineral content in aggregates demonstrated that the density and absorption rate specifications outlined in KS F 2527("Aggregates for Concrete") only offer indirect estimations of clay mineral levels. Furthermore, the investigation into the influence of clay mineral content on concrete performance suggests that a higher clay mineral content necessitates a corresponding increase in the unit quantity of aggregates to maintain adequate workability. This, however, has a detrimental effect on the compressive strength of the concrete.

• Korean Journal of Radiology
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• v.25 no.7
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• pp.673-683
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• 2024

Objective: To evaluate the role of visual and quantitative chest CT parameters in assessing treatment response in patients with severe asthma. Materials and Methods: Korean participants enrolled in a prospective multicenter study, named the Precision Medicine Intervention in Severe Asthma study, from May 2020 to August 2021, underwent baseline and follow-up chest CT scans (inspiration/expiration) 10-12 months apart, before and after biologic treatment. Two radiologists scored bronchiectasis severity and mucus plugging extent. Quantitative parameters were obtained from each CT scan as follows: normal lung area (normal), air trapping without emphysema (AT without emph), air trapping with emphysema (AT with emph), and airway (total branch count, Pi10). Clinical parameters, including pulmonary function tests (forced expiratory volume in 1 s [FEV1] and FEV1/forced vital capacity [FVC]), sputum and blood eosinophil count, were assessed at initial and follow-up stages. Changes in CT parameters were correlated with changes in clinical parameters using Pearson or Spearman correlation. Results: Thirty-four participants (female:male, 20:14; median age, 50.5 years) diagnosed with severe asthma from three centers were included. Changes in the bronchiectasis and mucus plugging extent scores were negatively correlated with changes in FEV1 and FEV1/FVC (ρ = from -0.544 to -0.368, all P < 0.05). Changes in quantitative CT parameters were correlated with changes in FEV1 (normal, r = 0.373 [P = 0.030], AT without emph, r = -0.351 [P = 0.042]), FEV1/FVC (normal, r = 0.390 [P = 0.022], AT without emph, r = -0.370 [P = 0.031]). Changes in total branch count were positively correlated with changes in FEV1 (r = 0.349 [P = 0.043]). There was no correlation between changes in Pi10 and the clinical parameters (P > 0.05). Conclusion: Visual and quantitative CT parameters of normal, AT without emph, and total branch count may be effective for evaluating treatment response in patients with severe asthma.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.513-521
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• 2024

This study aims to investigate how the social capital of middle school students is influenced by their grades, attitudes, and school interests, which are defined as school adjustment flexibility, and how they affect the social capital of middle school students. This study aims to provide a basis for policy discussions on how to shape the social capital of adolescents. The results of the analysis show that school adjustment flexibility has an impact on each factor of social capital. Trust is positively related to school attitudes, and norms are positively related to school compliance and school interest. Network has a positive effect on school attitude and a negative effect on school enjoyment. These results suggest that the higher the ability to follow the rules, the higher the norms of social capital, which suggests that social norms internalized at the individual level also affect group norms, which are the standards of behavior or rituals that members of a group follow when they want to behave as expected of them. We were able to find out that the normative domain of social capital is expanded by increasing the interest in school life of elementary and middle school students, and we confirmed that school class attitude is a major influencing factor in developing the network of social capital. Therefore, in order to increase the social capital capacity of elementary and middle school students, it is necessary to devise a plan to form various networks through multifaceted efforts to increase interest in school life and changes in school class attitude.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.19 no.4
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• pp.215-229
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• 2024

The purpose of this study was to explore various factors that affect the organizational commitment of health teachers' behavioral characteristics and explain the causal relationship between each factor. As an exploratory study, the subjects were about 500 people working as health teachers. A survey was conducted, and 190 responses were collected. Descriptive statistics were analyzed using SPSS, and the measurement model and hypotheses were tested using structural equation modeling. As a result of the analysis, the behavioral characteristics of health teachers were found to have a positive effect on their self-efficacy, and the behavioral characteristics and self-efficacy were found to have a positive effect on emotional commitment. In addition, health teachers' self-efficacy has a positive effect on emotional commitment, which means that rather than their behavioral characteristics having a direct effect on emotional commitment, their behavioral characteristics indirectly affect emotional commitment through a mediator called self-efficacy. It shows that it has an impact. In particular, it was confirmed that the school nurse's level of awareness of the importance of the task affected self-efficacy and emotional commitment. The implication of this study is that it explained the phenomenon of transfer of their behavioral characteristics to organizational commitment by empirically revealing that the competency, or behavioral characteristics, of health teachers are a factor affecting organizational commitment through self-efficacy. The goal is to empirically demonstrate that awareness of task importance, a job characteristic, affects self-efficacy and organizational commitment. The results of the study are expected to be able to suggest directions for capacity building and operation of health teachers.