• Journal of Korean Society of Disaster and Security
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• v.14 no.3
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• pp.29-38
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• 2021

Riverfront facilities are river space facilities used by citizens for the rest and convenience. Recently, although the importance of efficient maintenance of riverfront facilities is increasing, damaging facilities cases are increasing due to frequent floods. Currently, the inspections and diagnosis of river space facilities are limited to the main flood control facilities. And the standards for the maintenance and management of the riverfront facilities are insufficient. Utilization survey, which is the standard for managing river space facilities, is also inefficient in terms of manpower consumption and economic feasibility. This study uses mobile big data to classify river usage and conducts a survey for usability of river facilities to derive economic evaluation for usage performance. In the future, if economical method system that considers safety, usability, and durability is conducted and demanding analysis for each convenience facility is evaluated, it is expected that the efficient maintenance of riverfront facilities is perfomed better and the use of rivers by citizens will further increase.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.180-188
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• 2020

To replace Japanese coal ash used in the domestic cement production and to recycle large quantities of domestic pond ash, it is essential to develop the technologies for quality control of cement by using the domestic pond ash. Thus, in this study, the feasibility of using the pond ash as a raw material for cement was investigated through chemical composition and microstructure analysis. As a result, most of the domestic pond ash contained slightly more Fe2O3, chloride, and unburned carbon contents than Japanese coal ash. In particular, the contents of chloride were considerably low in the pond ash that was transferred to fresh water or collected from surface of landfill area. However, since circulating fluidized bed boiler coal ash had relatively high SO3 contents causing durability problems of cement, it was not suitable for use as a raw material for cement. Thus, to replace Japanese coal ash with the domestic pond ash, it is necessary to introduce the adjustment of mixture proportion of cement raw materials and the process of removing chloride in the pond ash.

• Journal of Chest Surgery
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• v.55 no.1
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• pp.69-76
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• 2022

Background: While the use of bioprosthetic valves for mitral valve replacement (MVR) is increasing, very few studies have compared bovine pericardial and porcine valves in the mitral position to help guide bioprosthetic selection. Methods: In the present study, patients who underwent MVR using bovine pericardial valves were compared with those who underwent MVR with porcine bioprostheses between January 1996 and July 2018. Those with prior MVR, infective endocarditis, congenital mitral valve disease, or ischemic mitral regurgitation were excluded. The primary outcomes were structural valve deterioration (SVD) and mitral valve reoperation from any cause, and death was regarded as a competing risk. Competing risk analysis and propensity score-matching were used for comparisons. Results: Among the 388 patients enrolled, pericardial and porcine bioprostheses were implanted in 217 (55.9%) and 171 (44.1%), respectively. Propensity score-matching yielded 122 pairs of patients that were well-balanced for all baseline covariates. No significant differences were observed between the groups in unadjusted (p=0.09) and adjusted overall survival (hazard ratio [HR], 1.13; 95% confidence interval [CI], 0.72-1.76; p=0.60). Competing risk analysis revealed no significant differences in the risks of mitral reoperation (HR, 1.07; 95% CI, 0.50-2.27; p=0.86) and development of SVD (HR, 1.57; 95% CI, 0.56-4.36; p=0.39) between the groups. Matched population analysis confirmed similar results regarding reoperation (HR, 0.99; 95% CI, 0.40-3.22; p=0.98) and SVD (HR, 1.39; 95% CI, 0.41-4.73; p=0.60). Conclusion: No significant differences in survival or valve durability were observed between bovine pericardial and porcine bioprosthetic MVR. These findings require further validation through studies with larger sample sizes.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.585-596
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• 2022

The purpose of this study is to propose an assessment method to analyze clay collectively referred to as fine particles of clay components contained in fine aggregates, and to propose quality standards for clay use through correlation with the performance of concrete to verify the properties of clay measured according to the method. As a result, it is analyzed that it will be suitably utilized as a method to assess the fine particles of the clay component of fine aggregates through the component analysis of XRF. Regarding the related quality standards, considering the error rate of about 10% of KCS 14 20 10, the related quality standards were analyzed to be safe when Al₂O₃+Fe₂O₃+MgO is 23.5% or less and SiO₂+K₂OSiO₂+K2₂O is 66.5% or more. To build on this study, it is expected that a comprehensive review will be conducted through additional follow-up studies such as on clay of coarse aggregates and durability analysis to establish a system for quality control of the soil fraction of aggregates.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.469-475
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• 2022

As the recent structure construction is constructed as a large-scale and deep underground excavation in close proximity to the building, the installation of retaining wall and supporters (Struts) has become complicated, and the number of supporters to avoid interference of the structural slab has increased. This construction process becomes a factor that causes an increase in construction joints of a structure, leakage and an increase in wall cracks. In addition, this reduced the durability and workability of the structure and led to an increase in the construction period. This study planned to dismantle the two struts simultaneously as a plan to reduce the construction joints, and corrected the earth pressure by assuming the reaction force value by the initial earth pressure and the measured data as the response ratio. After recalculating the corrected earth pressure through the iterative trial method, it was verified by numerical analysis that simultaneous disassembly of the two struts was possible. As a result of numerical analysis applying the final corrected earth pressure, the measured value for the design reaction force was found to be up to 197%. It was analyzed that this was due to the effect of grouting on the ground and some underestimation of the ground characteristics during design. Based on the result of calculating the corrected earth pressure in consideration of the response ratio performed in this study, it was proved analytically that the improvement of the brace dismantling process is possible. In addition, it was considered that the overall construction period could be shortened by reducing cracks due to leakage and improving workability by reducing construction joints. However, to apply the proposed method of this study, it is judged that sufficient estimations are necessary as there are differences in ground conditions, temporary facilities, and reinforcement methods for each site.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.11
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• pp.447-455
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• 2017

At the modern industry, the composite material has been widely used. Particularly, the material of carbon fiber reinforced plastic hardened with resin on the basis of fiber is excellent. As the specific strength and rigidity are also superior, it receives attention as the light material. Among these materials, the carbon fiber reinforced plastic using carbon fiber has the superior mechanical property different from another fiber. So, it is utilized in vehicle and airplane at which high strength and light weight are needed at the same time. In this paper, the tensile property due to the fiber design is investigated through the analysis study with CT specimen composed of carbon plastic reinforced plastic. At the stress analysis of CFRP composite material with hole, the fracture trend at the tensile environment is examined. Also, it is shown that the lowest stress value happens and the deformation energy of the pre-crack becomes lowest at the analysis model composed of the stacking angle of 60° through the result due to the stacking angle. On the basis of this study result, it is thought to apply the foundation data to anticipate the fracture configuration at the structure applied with the practical experiment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.59-66
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• 2008

In the construction site, to improve the man-dependent form work, non-stripping form has been studied but the developed non-stripping form was hard to applied with respect to the cost, form size and performance. This study is for evaluating the adaptability of the developed non-stripping form named as high performance permanent form (HPPF). To do this, the analytical approach and parametric study were performed based on the research for fundamental material characteristic of the HPPF. The target concrete structure is a wall structure because of its effectiveness of HPPF. To evaluate the structural efficiency of the HPPF applied wall structure, FEM analysis was performed to decide the maximum placing height at one time then it was applied to design the wall structure. In the result of the analysis, the HPPF applied wall structure showed the lots of advantages that it can reduce the cost resulted from reducing concrete and steel rebar even if it has same structural performance to the conventional concrete wall structure with same dimension. With this analysis result, it can be evaluated that the HPPF applied concrete structure can be a concrete structure with the long term durability in site.

• Journal of the Korea Society of Computer and Information
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• v.18 no.9
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• pp.201-208
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• 2013

The purpose of this paper is to study the effects of the competitiveness of intermediate goods and enterprise's core competency on customer value and enterprise performance. And it is the first time to investigate the intermediate product competitiveness with the variable of interest to recent corporate values and corporate customers with business performance by exploring their relationships. Intermediate products, which the competitiveness of products that target structure is introduced for the first time, and the relationships between intermediate goods competitive and product reliability, intermediate goods competitive and product innovation are studied in this paper. Further research on integral, modular, valuable, durability, by measuring parameters such as product innovation and product reliability are also conducted. Eight hypotheses are introduced for statistical hypothesis testing. Employees and typical intermediate products in electronic companies in China and South Korea are investigated. SPSS and AMOS models are applied to perform the statistical analysis. Analysis of the proposed models is fit to an acceptable level. Research results and limitations are discussed, and useful conclusions are drawn.

• 대한공업교육학회지
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• v.34 no.2
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• pp.179-204
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• 2009

As the concern with the educational training for human resources development in organizations grows, various programs are being offered in many places. Accordingly, the issue of securing the validity of the education and the importance of its assessment at the level of continuous quality management of the programs draw our attention. The purpose of this study is to offer the basic data of evaluation criteria for human resources development which knowledge-and-information saturated society requires, and also to draw out the greater area of human resources development educational program based on CIPP(Context, Input, Process, Product) model by Stufflebeam, an evaluation model concentrated on process, through literature and case study in and out of Korea. The result of the study is as follows. First, the evaluation areas drawn out by the greater sphere of context evaluation of human resources education program are needs analysis, goal setting, and organizational environment. Second, the evaluation areas drawn out by the greater sphere of input evaluation of human resources education program are educational program strategies, human resources, and physical resources. Third, the evaluation areas drawn out by the greater sphere of process evaluation of human resources education program are educational program management, teaching-learning strategies, and educational support environment. Fourth, the evaluation areas drawn out by the greater sphere of product evaluation of human resources education program are influence, effect, durability, and transference. The author supposes that these results will be able to become the basic materials for the systematic approach to educational programs through the analysis of evaluation criteria for and the greater sphere of educational program of human resources development.

• Journal of Chest Surgery
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• v.46 no.2
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• pp.104-110
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• 2013

Background: We reviewed the long-term outcomes of aortic root replacement at Asan Medical Center and investigated the predictors affecting mortality. Materials and Methods: A retrospective analysis was performed on 225 consecutive adult patients undergoing aortic root replacement with mechanical conduits (n=169), porcine aortic root prosthesis (n=23), or aortic homografts (n=33) from January 1992 to September 2009. The median follow-up duration was 6.1 years (range, 0 to 18.0 years). Results: The porcine root group was older than the other groups (freestyle $55.9{\pm}14.3$ years vs. mechanical $46.3{\pm}14.6$ years, homograft $48.1{\pm}14.7$ years; p=0.02). The mechanical group had the highest incidence of the Marfan syndrome (mechanical 22%, freestyle 4%, homograft 3%; p=0.01). Surgery performed for infective endocarditis was more frequent in the homograft group (mechanical 10%, freestyle 10%, homograft 40%; p<0.001). The overall 30-day mortality was 5.3% (12/225). Actuarial survival rates in the mechanical, porcine root, and homograft groups were 79.4%, 81.5%, and 83.5% at 5 years and 67%, 61.9%, and 61.1% at 10 years, respectively (p=0.73). By multivariate analysis, preoperative diabetes mellitus, older age, and longer cardiopulmonary bypass time were independent predictors of mortality. Incidence of postoperative complications, including infective endocarditis and thromboembolism were comparable in all of the groups. Conclusion: Aortic root replacement can be safely performed with different types of prostheses as the outcome was not affected by the choice of prosthesis. Further studies are required to assess the long-term durability of biological prostheses.