• Journal of the Korean Geotechnical Society
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• v.26 no.6
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• pp.39-44
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• 2010

In case of the design method, which is used in the inside and outside of the country, on corrugated multi plate structures, section modulus would be determined by assuming 2-dementioanl equivalent section of those structures. However, it is impossible to consider 3-dimentional effects when 2-dimentional design method is applied since structures are reinforced with a pattern of the 1200, 1600 mm reinforcements except the 800 mm reinforcement. Thus, in this study, technical specification standard is analyzed for the existing corrugated multi plate design methods, and section strengths, moments, and so on of equivalent and practical sections are compared and estimated using 3-dimentional FEM (finite element method) for semicircles and architectural features widely used. Based on the results of that analysis, analytical basis for 3-dimentional design of the CBS-RIB is suggested.

• Journal of Korean Medicine for Obesity Research
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• v.23 no.1
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• pp.10-17
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• 2023

Objectives: The aim of this study was to compare the total phenolic content of Korean Acanthopanax senticosus stems harvested in different seasons and provide basic data for developing functional reinforcement products based on the optimal harvesting time. Methods: Each sample harvested in different seasons was extracted and concentrated twice for 2 hours using 70% ethyl alcohol. Phenolic compounds were analyzed using high-performance liquid chromatography for simultaneous multi-component analysis of 14 compounds, including syringaresinol and so on. Results: The results showed that the stem of Korean Acanthopanax senticosus harvested in winter (November 29th) (EAS-5) had the highest phenolic content of 1.038%. The stem of Korean Acanthopanax senticosus harvested in autumn (October 1st) (EAS-4) showed the second-highest phenolic content of 0.764%, followed by the stem of Korean Acanthopanax senticosus harvested in spring (February 2nd) (EAS-1) with a content of 0.390%. On the other hand, the stem of Korean Acanthopanax senticosus harvested in the summer (June 2nd) (EAS-3) showed the lowest content at 0.342%. In conclusion, the stem of Korean Acanthopanax senticosus harvested in winter (EAS-5) showed the highest phenolic compound content. Conclusions: Considering the extraction yield and the total phenolic content, as well as the concentrations of key functional components such as eleutheroside B, chlorogenic acid, and syringaresinol in the 70% ethyl alcohol extract of Korean Acanthopanax senticosus, it is suggested that the stems of Korean Acanthopanax senticosus harvested during the winter season are suitable for the development of novel materials with enhanced anti-obesity functionality.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.234-234
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• 2021

국내 기반시설의 대부분은 1970년대 경제성장기에 건설되어 사용연수가 30년 이상 경과하였고 급격한 고령화가 진행 중이다. 1990년대 성수대교와 삼풍백화점의 붕괴는 시설물 유지관리의 중요성에 대한 전국민적 관심을 집중시켰고, 이에 정부는 1995년 「시설물의 안전관리에 관한 특별법」 제정을 시작으로 현재까지 다양한 정책 및 기준을 수립해왔다. 일반적으로 안전점검 및 정밀안전진단 등을 수행하여 시설물의 안전등급을 평가하고 결함에 대한 보수·보강을 실시하여 시설물을 유지·관리하고 있다. 그러나 유지관리 예산은 한정적이기 때문에 모든 결함에 대한 보수·보강 사업을 실시할 수 없는 실정이다. 이에 보수·보강 조치의 우선순위를 선정하는 것이 필요하며, 관련 법령 세부지침에는 부재의 중요도, 결함의 심각성, 경제성을 고려한 우선순위지수(PI, Priority Index)를 제시하고 있다. 이 식은 전문가의 주관적인 판단에 의해 영향도를 50~100%범위 안에서 조정할 수 있으며, 일부 특정 부재는 동일한 가중치가 설정되어 있다. 또한 결정적으로 보수보강을 통한 효과를 효율적으로 고려하지 못하고, 대부분 경제성에 의해 우선순위가 결정되는 한계점이 발생한다. 따라서, 본 연구에서는 몇 가지 사례분석을 통해 현재 우선순위지수에 대한 문제점을 고찰하고 이를 개선할 수 있는 우선순위 산정식(PI)을 제시하였다. 과거 유지관리 시행 초기에는 보수보강 사례가 부족하였지만 현재는 수십년간의 축적된 자료를 바탕으로 제시된 산정식을 충분히 활용할 수 있을 것으로 판단된다. 향후 보수보강 효과를 정량화하는 방법에 대한 추가적인 연구가 수행된다면 더욱 경제적인 측면에서 우선순위를 산정할 수 있을 것이며 노후화된 기반시설 유지관리방안에 효과적으로 사용될 것으로 기대된다.

• Advances in concrete construction
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• v.16 no.4
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• pp.205-216
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• 2023

Concrete structures may become vulnerable during their lifetime due to several reasons such as degradation of their material properties; design or construction errors; and environmental damage due to earthquake. These structures should be repaired or strengthened to ensure proper performance for the current service load demands. Several methods have been investigated and applied for the strengthening of reinforced concrete (RC) structures using various materials. Fiber reinforced polymer (FRP) reinforcement is one of the most recent type of material for the strengthening purpose of RC structures. The main objective of the present research is to identify the behavior of reinforced concrete slabs strengthened with FRP bars by using near surface mounted (NSM) technique. Validation study is conducted based on the experimental test available in the literature to investigate the accuracy of finite element models using LS-DYNA to present the behavior of the models. A parametric analysis is conducted on the effect of FRP bar diameters, number of grooves, groove intervals as well as width and height of the grooves on the flexural behavior of strengthened reinforced slabs. Performance of strengthening RC slabs with NSM FRP bars was confirmed by comparing the results of strengthening reinforced slabs with control slab. The numerical results of mid-span deflection and stress time histories were reported. According to the numerical analysis results, the model with three grooves, FRP bar diameter of 10 mm and grooves distances of 100 mm is the most ideal and desirable model in this research. The results demonstrated that strengthening of reinforced concrete slabs using FRP by NSM method will have a significant effect on the performance of the slabs.

• Journal of Korean Clinical Nursing Research
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• v.30 no.1
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• pp.24-34
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• 2024

Purpose: This study aimed to identify factors influencing nurses' intention to care for COVID-19 patients based on the theory of planned behavior, and to test the moderating effect of perceived behavior control between attitude, subjective norms, and nurses' intention to care. Methods: The participants were 167 nurses working at two designated hospitals for infectious diseases located in J and C city, South Korea. Data were collected from October 10th to 25th, 2020, and analyzed using independent t-test, ANOVA, and Pearson correlation coefficient, and hierarchical multiple regression analysis. The moderating effect was analyzed using the Process Macro model 1 (95% confidence interval, 10,000 bootstrapping), and a simple slope analysis was performed to identify the moderating effect of perceived behavior control. Results: The factors affecting nurses' intention to care for patients with COVID-19 were attitude toward the behavior (β=.32, p<.001) and perceived behavior control (β=.37, p<.001) in model 1, attitude toward the behavior (β=.28, p<.001) and perceived behavior control (β=.36, p<.001), and perspective taking (β=.26, p<.001) in model 2. The explanation power of this model was 65.0% (F=18.41, p<.001). The moderating effect of perceived behavioral control was statistically significant in the relationship between subjective norms and intention to care for patients with COVID-19 (F=16.37, p<.001). In the simple slope analysis, the reinforcement effect was greatest when the level of perceived behavioral control was at the mean (95% CI=0.46~0.67) and high (95% CI=0.70~1.08). Conclusion: Developing and applying a training program that enhances confidence and improves empathy is necessary to increase nurses' intention to care for COVID-19 patients.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.4
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• pp.315-326
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• 2024

In this study, the Delphi method and AHP (analytic hierarchy process) were used to evaluate tunnel collapse risk from a comprehensive and multifaceted perspective. Influence factors were established through literature reviews, previous studies, and brainstorming sessions with expert groups, resulting in the construction of five main classification systems. A panel of 21 experts was formed, and three rounds of Delphi surveys were conducted to prevent errors and biases in the expert judgment process, thereby enhancing reliability. Ultimately, 14 influence factors were identified through CVR (content validity ratio) and COV (coefficient of variation) analyses of the experts' responses. Subsequently, the AHP method was applied to assess the relative importance of each influence factor and calculate the final composite weights. The timing of support and reinforcement had the highest priority, followed by groundwater inflow, joint conditions, support pattern levels, and auxiliary methods. These findings help identify the key factors affecting tunnel collapse risk and provide a foundation for developing strategies to improve tunnel safety.

• The Journal of the Convergence on Culture Technology
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• v.10 no.4
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• pp.595-600
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• 2024

As the use of artificial intelligence technologies such as machine learning increases in research fields that predict learning outcomes or optimize learning pathways, the use of artificial intelligence in education is gradually making progress. This research is gradually evolving into more advanced artificial intelligence methods such as deep learning and reinforcement learning. This study aims to improve the method of predicting future learning performance based on the learner's past learning performance-history data. Therefore, to improve prediction performance, we propose conditional probability applying the Markov Chain method. This method is used to improve the prediction performance of the classifier by allowing the learner to add learning history data to the classification prediction in addition to classification prediction by machine learning. In order to confirm the effectiveness of the proposed method, a total of more than 30 experiments were conducted per algorithm and indicator using empirical data, 'Teaching aid-based early childhood education learning performance data'. As a result of the experiment, higher performance indicators were confirmed in cases using the proposed method than in cases where only the classification algorithm was used in all cases.

• Journal of the Korea Institute of Building Construction
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• v.24 no.4
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• pp.507-515
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• 2024

Recent advancements in Building Information Modeling(BIM) have significantly impacted the construction industry, driving competitiveness and innovation. However, rebar construction, a critical component influencing project quality and cost, has lagged behind in BIM adoption. Traditional methods relying heavily on 2D drawings for rebar detailing have hindered efficiency and introduced potential errors. This paper presents a novel system designed to automate the detailed modeling of rebar, thereby promoting BIM integration within rebar construction and optimizing construction management processes. The system leverages confirmed structural drawings from the post-structural design phase to automatically generate intricate rebar models for columns and beams. To ensure adherence to domestic structural design standards, the system is developed using C# programming language and the Revit API. By automating rebar modeling, this system aims to minimize human error, reduce labor-intensive tasks, and enhance overall rebar construction efficiency through the effective utilization of generated rebar model data.

• Geotechnical Engineering
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• v.12 no.3
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• pp.127-148
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• 1996

Recently, foundations of heavy structures such as bridge abutments have been built on slopes or near the crest of slopes at an increasing rate. Because the bearing capacity of such foundations is considerably lower than the bearing capacity of the same soil on a level ground, deep footings such as piles and caissons are often used. However, the costs of such methods are generally very high. One of the new techniques to overcome the problem is to place reinforcing members such as geosynthetics or metal strips horizontally at some depths beneath the footings. Rational methods of analysis to predict the bearing capacity of footings in reinforced slopes are therefore needed. This paper proposes an analytical method for estimating the increase in bearing capacity gained from the included horizontal strips or ties of tensile reinforcing in the foundation soil below the footing built near the crest of a slope. A failure mechanism, including the concept of'wide slab effect', adopted in the present study for analyzing the bearing capacity of foundations in reinforced slopes, is established through the observed model test behaviors described by Binquet SE Lee and Huang et al, and the Boussinesq solutions. The analytical results are then compared with the experimental data described in the paper by Huang et al. Also in order to properly evaluate the soil reinforcement interaction, typical pullout test values of the apparent friction coefficient, which usually vary with depths owing to both the increase of the shearing volume and the increase in local stress caused by soil dilatancy, are analyzed and related functionally. Furthermore, analytical parametric studies are carried out to investigate the effect and significance of various pertinent parameters associated with design of reinforced slope foundations. Keywords : Bearing capacity, Reinforced slope, Slab effect, Friction coefficient.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.95-102
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• 2012

The serious issue of tall building is to ensure the fire resistance of high strength concrete. Therefore, Solving methods are required to control the explosive spalling. The fire resistant finishing method is installed by applying a fire resistant material as a light-weight material to structural steel and concrete surface. This method can reduce the temperature increase of the reinforcement embedded in structural steel and concrete at high temperature due to the installation thickness control. This study is interested in identifying the effectiveness of light-weight fire protection material compounds including the inorganic admixture such as fly ash, meta-kaolin and light-weight aggregate as the fire resistant finishing materials through the analysis of fire resistance and components properties at high temperature. Also, this paper is concerned with change in microstructure and dehydration of the light-weight fire protection materials at high temperatures. The testing methods of fire protection materials in high temperature properties are make use of SEM and XRD. The study results show that the light-weight fire resistant finishing material composed of fly ash, meta-kaolin and light-weight aggregate has the thermal stability of the slight decrease of compressive strength at high temperature. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction by the reason of the thermal analysis result not showing the decomposition of calcium hydrate. Developed light-weight fire protection materials showed good stability in high Temperatures. Thus, the results indicate that it is possible to fireproof panels, fire protection of materials.