• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.57-65
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• 2024

In a fire-resistant structure, uncertainties arise in factors such as ventilation, material elasticity modulus, yield strength, coefficient of thermal expansion, external forces, and fire location. The ventilation uncertainty affects thefactor contributes to uncertainties in fire temperature, subsequently impacting the structural temperature. These temperatures, combined with material properties, give rise to uncertain structural responses. Given the nonlinear behavior of structures under fire conditions, calculating fire fragility traditionally involves time-consuming Monte Carlo simulations. To address this, recent studies have explored leveraging machine learning algorithms to predict fire fragility, aiming to enhance efficiency while maintaining accuracy. This study focuses on predicting the fire fragility of a steel moment frame building, accounting for uncertainties in fire size, location, and structural material properties. The fragility curve, derived from nonlinear structural behavior under fire, follows a log-normal distribution. The results demonstrate that the proposed method accurately and efficiently predicts fire fragility, showcasing its effectiveness in streamlining the analysis process.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.735-746
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• 2002

The task of plastic theory is twofold: first, to set up relationships between stress and strain that adequately describe the observed plastic deformation of metals, and second, to develop techniques for using these relationships in studying of the mechanics of metal forming processes, and the anlaysis and design of structures. One of the major problems in the theory of plasticity is to describe the behavior of work-hardening materials in the plastic range for complex loading histories. This can be achieved by formulating constitutive laws either in the integral or differential forms. To adequately predict the response of steel members during cyclic loading, the hardening rule must account for the features of cyclic stress-strain behavior. Neithe of the basic isotropic and kinematic hardening rules is suitable for describing cyclic streess-strain behavior, although a kinematic hardening rule describes the nearly linear portions of the stabilized hystersis loops. There is also a limited expansion of the yield surface as predicted by the isotropic hardening rule. Strong ground motions or wind gusts affect the complex and nonproportional loading histories in the inelastic behavior of structues rather than the proportional loading. Nonproportional loading is defined as externally applied forces on the structure, with variable ratios during the entire loading history. This also includes the rate of time-dependency of the loads. For nonproportional loading histories, unloading may take place along a chord instead of the radius of the load surface. In such cases, the shape of the stress-strain curve has to be determined experimentally for all non-radial loading conditions. The plasticity models including two surface models ae surveyed based on a yield surface and a bound surface that represent a state of maximum stress. This paper is concerned with the improvement of a plasticity models of the two-surface type for structural steel. This is follwed by an overview of plasticity models on structural steel. Finally the need for further research is identified.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.407-414
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• 2004

Bridges in common use are expected to have more varieties of load in their connected members and bolts than in construction. Faults in connection members or bolts occur so often according to the time flow. One of the purposes of this study is to find out the behavior and structural features of high-tension bolted joints with faults that are very difficult and cost much to find out through experimentation with finite element analysis. Another purpose of this study is to provide sufficient data, estimated experimental results, and the scheme of the test plate for an economical experimental study in the future. Surveys of bridges with a variety of faults and statistical classifications of their faults were performed, as was a finite element analysis of the internal stress and the sliding behavior of standard and defective bridge models. The finite element analysis of the internal stress was performed according to the interval of the bolt, the thickness of the plate, the distance of the edge, the diameter of the bolt, and the expansion of the construction. Furthermore, the analysis explained the sliding behavior of high-tension bolt joints and showed the geometric non-linear against the large deformation, and the boundary non-linear against the non-linear in the contact surface, including the material non-linear, to best explain the exceeding of the yield stress by sliding. A normally bolted high-tension bolt joint and deduction of bolt tension were also analyzed with the finite element analysis of bridge-sliding behavior.

• Progress in Medical Physics
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• v.20 no.3
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• pp.119-124
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• 2009

Stents are frequently used throughout the human body. They keep pathways open in vascular or nonvascular duct for a long time. Therefore its stability is very important factor. In recent years, aconsiderable amount of research has been carried out in order to estimate mechanical properties of the stent such as expansion pressure behavior, radial recoil and longitudinal recoil using FEM (Finite element analyses). However, published works on simulation of stent fatigue behavior using FEM are relatively rare. In this paper, a nonlinear finite-element methodwas employed to analyses the compression of a stent using external pressure and fatigue behavior. Finite element analyses for the stent system were performed using NASTRAN FX. In conclusion this paper shows how the stent is behaved in the body, and its fatigue behavior.

• Journal of Korean Academy of Nursing Administration
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• v.8 no.3
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• pp.431-439
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• 2002

Purpose : Nursing profession has been rapidly changed due to the development of bioscience and the change of medical service environment. Nursing profession that has been focused on only care giver's role like mother's in tradition, is required careful reflection new nursing role to cope properly to the change of medical service environment. In nursing profession, the concept of the role was used without an accurate definition, as a results, the concept of the role was mixed with the concept of the "activity", "job" and "function". Therefore, concept analysis of the role in nursing profession is needed to remove conceptual ambiguous and make confirm the true meaning of the role. Concept analysis is a strategy that examine the characteristics of a concept. It is a formal linguistic exercise to determine those defining attributes. The basic purpose of concept analysis is to clarify ambiguous concept in theory, and propose operational definition which reflects the theoretical base of the concept. Method : In this study, the concept of the role in nursing profession which was analyzed based on the steps of concept analysis by Walker & Avant(1988). Results : The attributes of the concept of the role in nursing profession are : 1. Basic factors to construct social structure. 2. Expected attitudes, values, behavior patterns according to the social status and position in social structure. 3. Perceptive attitudes, values, behavior patterns in order to social interaction. 4. Acquiring through continuous communication and learning. 5. Not fixative but changeable. The antecedents of the role in nursing profession are : 1. The social status and position which is possessed by a person. 2. Expected attitudes, values, behavior patterns according to the social status and position in social structure. 3. Acquiring through continuous interaction, communication, and learning process. And the consequences of the role in nursing profession are : 1. The role maintenance and the role expansion as a positive consequences. 2. The role conflict and the role loss as a negative consequences. Conclusion : Through this concept analysis, the concept of the role in nursing profession is defined as As basic factors to construct social structure, person's attitudes, values, behavior patterns which are expected from other social members according to person's social status and position, and perceived and acquired through continuous interaction, communication, and leaning process.

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.35-43
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• 2017

In this study, the pull-out resistance behavior of the anchor with the bump type resistors at the anchor body was experimentally investigated. In the model tests, the pull-out resistance was measured by pulling out the anchor at a constant speed. Anchor body was installed in the center of the circular sand tank. Pull-out tests were conducted for 10 conditions. The anchor type (existence of the resistor), the friction conditions of the anchor body surface ($1/3{\phi}$, $2/3{\phi}$, ${\phi}$), the bump type resistor set number (1set, 2set, 4set), and the height of resistors (0.05d, 0.10d, 0.20d) were varied. The load-displacement relationship for each conditions was measured during the pull-out tests at a constant speed (1 mm/min). Maximum pull-out length was 80 mm. As a result, the pull-out behavior of the friction type anchor and the expansion type anchor was different. As the number of resistor increased, the maximum pull-out resistance increased and the residual pull-out resistance ratio increased significantly, which were at 171~591 percent larger than that of the friction type anchor.

• Journal of Digital Convergence
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• v.19 no.11
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• pp.181-199
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• 2021

Recently, financial companies are promoting chatbot services in line with the reduction of branches and the expansion of non-face-to-face services. However, it is difficult to expand the chatbot services at once in the presence of technical limitations and constraints of internal and external environment. Therefore, it is necessary to analyze the various situations of chatbot service to preemptively identify problems that can occur in stages and seek solutions. This study conducted interviews with 12 field practitioners and researchers to examine the intentions and behaviors of financial chatbot service users and interpreted them using TPB. The study revealed the characteristics of 'feelings and attitudes' such as convenience or inconvenience from the chatbot experience, 'subjective norms' such as herd behavior or the yearning for empathy of others, and 'behavioral control' according to the recognition of difficulty or convenience of chatbot use process. This study shows that this characteristic can affect the intention and actual behavior of users to use chatbot service continuously. In the future research, it is necessary to empirically study specific intentions and influence factors for actual users.

• Journal of Korea Trade
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• v.26 no.5
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• pp.23-38
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• 2022

Purpose - This research intends to find out whether R&D cost stickiness shows differentiated aspects depending on exports in Korea. A cost behavior that indicates a lower rate of costs decrease when sales decrease than the rate of costs increase when sales increase is called cost stickiness. This sticky cost behavior is caused by considering the adjusting costs. This study aims to empirically verify that R&D cost stickiness is greater in export firms than in non-export firms. We also investigate the effect of exports on R&D cost stickiness is nonlinear. Design/methodology - We obtain data for the analysis from Kis-Value and TS2000 from 2012 to 2020. This study tests for R&D cost stickiness of exports using the cost stickiness model developed by Anderson et al. (2003) that is used in a lot of prior literature. To explore the nonlinear behavior of R&D cost stickiness we include a quadratic term of exports in our model. Findings - The results of our analysis are as follows. First, we observed that R&D costs of export firms are more sticky than that of non-export firms. Our result indicated that export firms are less likely to reduce R&D costs in decreasing sales periods in preparation for future sales recovery. Second, our empirical evidence shows that export firms view R&D costs much favorably. However, we hypothesize that the effect of export intensity on R&D costs may not necessarily be linear. Our result shows the effect of exports intensity on R&D stickiness is thus nonlinear, forming a reverse U-shaped curve. When export intensity exceeds a certain threshold, the growth rate of R&D costs appears to be viewed negatively. Firms with relatively high export intensity do not support R&D costs, viewing them as taking away firms' resources from other more productive costs. On the contrary, those with export intensity under the threshold view R&D costs as beneficial and therefore promote further R&D costs when revenue decreases. Originality/value - The results of this research can contribute academically to the expansion of empirical research on R&D cost stickiness. R&D cost stickiness varies by industry. As a result of our research, the managers of export firms recognize the importance of R&D to lead innovation. We expected that this research contributes to further studies on R&D costs and cost stickiness. Second, this research has implications from a business perspectives. Our findings of export firms' R&D stickiness suggest that export firms' managers should consider keeping the stickiness of R&D when revenue decreases because it is essential for exporting firms to maintain their R&D stickiness to secure long-term competitiveness. R&D stickiness can be used on a practical basis to emphasize the need for continuous investment in exporting firms' R&D activities.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.193-204
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• 2023

In recent years, the concept of influencer marketing has experienced rapid growth in both academia and industry, leading to its emergence as a crucial consideration in the marketing strategies of many businesses. Despite the significance and expansion of the influencer market, however, research on the topic has not kept pace with its growth. Thus, this study seeks to address this gap by empirically analyzing the impact of influencer characteristics on consumer behavior through the coexistence of buyers and providing an empirical contribution to expand the relevant literature. To accomplish this, a survey was conducted with a sample of 400 individuals who had purchased a product through an influencer, and 384 responses were ultimately utilized in the analysis. The results revealed that the attractiveness and empathy of influencers had a positive impact on satisfaction among coexisting buyers, while also having a negative impact on dissatisfaction. In contrast, expertise had no impact on satisfaction, but a positive impact on dissatisfaction. Moreover, satisfaction was found to have a positive impact on brand image and recommendation intention, whereas dissatisfaction had a negative impact on both. Overall, this study adds to the growing body of literature on influencer marketing by providing empirical evidence of the impact of influencer characteristics on consumer behavior, specifically through the lens of coexistence with buyers. These findings hold important implications for businesses looking to develop effective influencer marketing strategies that can enhance their brand image and recommendation intention among consumers.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.5
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• pp.285-290
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• 2013

Both full linear and shallow water edge waves are compared to get a better understanding of edge wave behavior. By using method of separation of variables, we are able to get solution of full linear edge wave presented by Ursell (1952) without derivation. The shallow water edge waves show dispersive features despite being derived from shallow water equations. When bottom slope is mild enough, shallow water edge wave tends to linear edge wave and has some advantages of manipulation. Solution of edge wave generated by a moving landslide of Gaussian shape is constructed by an expansion of shallow water normal modes. Numerical results are presented and discussed on their main features.