• Computers and Concrete
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• v.31 no.3
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• pp.267-276
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• 2023

The main purpose of the current research is to develop an efficient two variables trigonometric shear deformation beam theory to investigate the buckling behavior of symmetric and non-symmetric functionally graded carbon nanotubes reinforced composite (FG-CNTRC) beam resting on an elastic foundation with various boundary conditions. The proposed theory obviates the use to shear correction factors as it satisfies the parabolic variation of through-thickness shear stress distribution. The composite beam is made of a polymeric matrix reinforced by aligned and distributed single-walled carbon nanotubes (SWCNTs) with different patterns of reinforcement. The material properties of the FG-CNTRC beam are estimated by using the rule of mixture. The governing equilibrium equations are solved by using new analytical solutions based on the Galerkin method. The robustness and accuracy of the proposed analytical model are demonstrated by comparing its results with those available by other researchers in the existing literature. Moreover, a comprehensive parametric study is presented and discussed in detail to show the effects of CNTs volume fraction, distribution patterns of CNTs, boundary conditions, length-to-thickness ratio, and spring constant factors on the buckling response of FG-CNTRC beam. Some new referential results are reported for the first time, which will serve as a benchmark for future research.

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.57-63
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• 2023

The external weather conditions including temperature and wind speed in the Saemangeum reclaimed land is different from that of the inland, affecting the internal environment of the greenhouse. Therefore, it is important to select an appropriate covering material considering the insulation effect according to the type and characteristics of the covering material considering the weather condition in the Saemangeum reclaimed land. A hexahedral insulation chamber was designed to evaluate the insulation efficiency of each glass-clad material in the outside weather condition in reclaimed land. In order to evaluate the insulation effect of each covering material, a radiator was installed and real-time power consumption was monitored. 16-mm PC (polycarbonate), 16-mm PMMA (polymethyl methacrylate), 4-mm greenhouse glass, and 16-mm double-layered glass were used as the covering materials of the chamber. In order to understand the effect of the external wind directions, the windward and downwind insulation properties were evaluated. As a result of comparing the thermal insulation effect of each greenhouse cover material to single-layer glass, the thermal insulation effect of double-layer glass was 16.9% higher, while PMMA and PC were 62.5% and 131.2% higher respectively. On average the wind speed on the windward side was 53.1% higher than that on the lee-wind side, and the temperature difference between the inside and outside of the chamber at the wind ward side was found to be 52.0% larger than that on the lee ward side. During the experiment period, the overall heating operation time for PC was 39.2% lower compared to other insulation materials. Showing highest energy efficiency, and compared to PC, single-layer glass power consumption was 37.4% higher.

• Journal of Industrial Convergence
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• v.20 no.11
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• pp.85-93
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• 2022

As of the end of 2019, the total population nationwide was 51,849,861, and over the past five years, the population per household has decreased by 1.52% annually from 2.45 in 2015 to 2.31 in 2019. Looking at the current status of population distribution by age group, Busan metropolitan city had the highest proportion of senior citizens aged 65 or older at 18.2%, and Sejong Special Self-Governing city had the lowest at 9.4%. In particular, as of 2019, the population of the mobility handicapped was 15,219,000 nationwide, showing a ratio of about 29.4% of the total population. Therefore, it is important to secure the right to move according to the mobile facilities so that the mobility handicapped can move safely and conveniently. Against this background, this study places value on transportation welfare facilities centered on the mobility handicapped for safe and convenient movement, and in particular, in proposing measures to cope with the entry of an aging society and the continuous increase of the mobility handicapped, the transportation facilities, The purpose of this study is to analyze the impact of welfare facilities on the mobility handicapped and suggest implications. As a research method, the results of statistical analysis methods were presented through major preceding studies and expert surveys.

• Explosives and Blasting
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• v.40 no.4
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• pp.15-26
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• 2022

With the recent increase in old and dangerous buildings, the demand for technology in the field of structure demolition is rapidly increasing. In particular, in the case of structures with severe deformation of damage, there is a risk of deterioration in stability and disaster due to changes in the load distribution characteristics in the structure, so rapid structure demolition technology that can be efficiently dismantled in a short period of time is drawing attention. However, structural deformation such as unauthorized extension or illegal remodeling occurs frequently in many old structures, which is not reflected in structural information such as building drawings, and acts as an obstacle in the demolition design process. In this study, as an effective way to overcome the discrepancy between the structural information of old structures and the actual structure, access to actual structures through 3D modeling was considered. 3D point cloud data inside and outside the building were obtained through LiDAR and drone photography for buildings scheduled to be blasting demolition, and precision matching between the two spatial data groups was performed using an open-source based spatial information construction system. The 3D structure model was completed by importing point cloud data matched with 3D modeling software to create structural drawings for each layer and forming each member along the structure slab, pillar, beam, and ceiling boundary. In addition, the modeling technique proposed in this study was verified by comparing it with the actual measurement value for selected structure member.

• The Korean Journal of Coaching Psychology
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• v.7 no.2
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• pp.21-46
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• 2023

The current study aimed to develop and evaluate the effectiveness of a group coaching program to improve college students' career exploration behaviors based on the self-affirmation theory. Participants were undergraduate students at a University in Seoul and volunteered in the program during the break. The group coaching program was conducted twice a week during three weeks, a total of six times, and each session lasted 2 to 2.5 hours. In this study, the effect of self-affirmation embedded in the group coaching program on various psychological variables and college students' career exploration behaviors were examined. A mixed-randomized analysis was conducted to compare the pre, post, and follow-up tests of the experimental, comparison, and no-treatment control groups, each consisting of 18 participants. The results showed that participants in the experimental group coaching condition showed more significant improvements in psychological resources, career self-efficacy, openness, problem-focused coping, and career exploration behaviors compared to the comparison and control groups, and these results were maintained even after the program ended. The implications of this study for coaching theory and practice, as well as limitations and future research directions, were discussed.

• Membrane and Water Treatment
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• v.14 no.3
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• pp.129-140
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• 2023

The appropriate injection of H₂O₂ is essential to produce hydroxyl radicals (OH·) by mixing H₂O₂ quickly and exposing the resulting H₂O₂ solution to UV irradiation. This study focused on evaluating mixing device of H₂O₂ as a design factor of UV/H₂O₂ AOP pilot plant using a surface water. The experimental investigation involved both experimental and model-based analyses to evaluate the mixing effect of different devices available for the H₂O₂ injection of a tubular hollow pipe, elliptical type of inline mixer, and nozzle-type injection mixer. Computational fluid dynamics analysis was employed to model and simulate the mixing devices. The results showed that the elliptical type of inline mixer showed the highest uniformity of 95%, followed by the nozzle mixer with 83%, and the hollow pipe with only 18%, after passing through each mixing device. These results indicated that the elliptical type of inline mixer was the most effective in mixing H₂O₂ in a bulk. Regarding the pressure drops between the inlet and outlet of pipe, the elliptical-type inline mixer exhibited the highest pressure drop of 15.8 kPa, which was unfavorable for operation. On the other hand, the nozzle mixer and hollow pipe showed similar pressure drops of 0.4 kPa and 0.3 kPa, respectively. Experimental study showed that the elliptical type of inline and nozzle-type injection mixers worked well for low concentration (less than 5mg/L) of H₂O₂ injection within 10% of the input value, indicating that both mixers were appropriate for required H₂O₂ concentration and mixing intensity of UV/ H₂O₂ AOP process. Additionally, the elliptical-type inline mixer proved to be more stable than the nozzle-type injection mixer when dealing with highly concentrated pollutants entering the UV/H₂O₂ AOP process. It is recommended to use a suitable mixing device to meet the desired range of H₂O₂ concentration in AOP process.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.471-480
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• 2023

Purpose: This study intends to present a future research direction for military education by identifying and analyzing research trends in the field of education related to soldiers in academic research published in Korea. Method: In domestic academic papers published from 2000 to 2022, 269 final papers were selected from among the papers conducted on the subjects of 'soldiers' and 'education'. The final selected literature was analyzed by categorizing it into year, research subject, research method type, number of researchers, research topic, and research content. Result: First, since 2010, the number of studies has gradually increased, and 31 articles were published in 2021, with the largest number of studies. Second, the largest number of studies were conducted on the entire military, followed by the Army and Nursing Officers. Third, qualitative research methods were used a little more in research methods. Fourth, the number of researchers with two or more researchers was steadily increasing. Fifth, most of the research topics were development, design, and improvement. Sixth, in terms of detailed research contents, most of the studies were related to soldiers' spirit(mental force) education and military education and training. Conclusion: Through this study, it was confirmed that military education was studied in various subjects. The direction of future research should be in-depth research from various perspectives with a lot of interest in military education and safety.

• Imaging Science in Dentistry
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• v.53 no.3
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• pp.193-198
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• 2023

Purpose: Artificial intelligence (AI) is poised to play a major role in medical diagnostics. Periodontal disease is one of the most common oral diseases. The early diagnosis of periodontal disease is essential for effective treatment and a favorable prognosis. This study aimed to assess the effectiveness of AI in diagnosing periodontal bone loss through radiographic analysis. Materials and Methods: A literature search involving 5 databases (PubMed, ScienceDirect, Scopus, Health and Medical Collection, Dentistry and Oral Sciences) was carried out. A specific combination of keywords was used to obtain the articles. The PRISMA guidelines were used to filter eligible articles. The study design, sample size, type of AI software, and the results of each eligible study were analyzed. The CASP diagnostic study checklist was used to evaluate the evidence strength score. Results: Seven articles were eligible for review according to the PRISMA guidelines. Out of the 7 eligible studies, 4 had strong CASP evidence strength scores (7-8/9). The remaining studies had intermediate CASP evidence strength scores (3.5-6.5/9). The highest area under the curve among the reported studies was 94%, the highest F1 score was 91%, and the highest specificity and sensitivity were 98.1% and 94%, respectively. Conclusion: AI-based detection of periodontal bone loss using radiographs is an efficient method. However, more clinical studies need to be conducted before this method is introduced into routine dental practice.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.34 no.3
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• pp.59-87
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• 2023

The aim of this study is to provide practical instances of implementing picture book reading sessions within school libraries to enhance language proficiency and foster emotional stability among lower-grade multicultural students hailing from foreign backgrounds. The research outlines the design and execution of a picture book reading program tailored for multicultural students, with analysis based on the outcomes of actual classroom implementations. In the course of the study, existing literature pertaining to the use of picture books for enhancing multicultural education and language skills was reviewed. This informed the development of a structured class procedure by extracting core components. Indeed, 43 multicultural students in five classes in the first and second grades of A Elementary School in Gyeonggi-do were given three pilot classes for each class for 20 weeks and a total of 100 picture book reading classes, each with 17 main lessons. This study establishes the positive impact of picture book reading classes on the Korean language comprehension of multicultural students. The results confirm positive improvements in students' ability to understand Korean, as evidenced by enhanced Korean expression and presentation skills, increased library usage, and a positive shift in classroom attitude. The procedure for reading picture books using school libraries proposed in this study was actually conceived and developed in the course of class operation in the school education field, reflecting the changes brought about by the increase of multicultural students and the need to improve the class environment. Through this practical investigation, important insights have been extracted regarding how picture book reading sessions designed for elementary school students from multicultural backgrounds can enhance the classroom environment and elevate learning outcomes.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.47-59
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• 2023

In this research, laboratory tests were conducted on clayey sand (SC) to analyze its physical properties, compaction/permeability characteristics, and stress-strain behavior. The main objective was to determine the transitional fines content at which the mechanical properties of sand transition to those of clay, resulting in a change in the geotechnical behavior of the material. Additionally, to assess the practical applicability of SC soil, field data from a soft ground improvement site with significant settlement issues were collected. The settlement characteristics derived from laboratory tests and numerical simulations were then compared and analyzed in relation to the actual settlement data obtained from the field, aiming to evaluate the suitability of the SC soil as a compaction target layer. The laboratory tests and compaction analysis showed that the SC soil exhibited a distinct change in mechanical properties, shifting from sandy behavior to clayey behavior when the fines content exceeded 25%. This transition in mechanical behavior was found to be closely correlated with the content of clay particles within the material. Through numerical simulations of the soft ground site, it was verified that the use of clayey sand with a fines content exceeding the transitional level as a compaction target layer resulted in settlements that closely aligned with the measured settlements, with an average agreement of 91.2%. Based on these findings, it is deemed advisable to incorporate clayey sand with a fines content exceeding the transitional level as part of the compaction target layer in the design of soft ground improvements.