• Structural Engineering and Mechanics
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• v.28 no.4
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• pp.373-386
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• 2008

In this study stochastic analysis of non-linear dynamical systems under ${\alpha}$-stable, multiplicative white noise has been conducted. The analysis has dealt with a special class of ${\alpha}$-stable stochastic processes namely sub-Gaussian white noises. In this setting the governing equation either of the probability density function or of the characteristic function of the dynamical response may be obtained considering the dynamical system forced by a Gaussian white noise with an uncertain factor with ${\alpha}/2$- stable distribution. This consideration yields the probability density function or the characteristic function of the response by means of a simple integral involving the probability density function of the system under Gaussian white noise and the probability density function of the ${\alpha}/2$-stable random parameter. Some numerical applications have been reported assessing the reliability of the proposed formulation. Moreover a proper way to perform digital simulation of the sub-Gaussian ${\alpha}$-stable random process preventing dynamical systems from numerical overflows has been reported and discussed in detail.

• Journal of Applied Reliability
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• v.16 no.1
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• pp.56-63
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• 2016

Purpose: The purpose of this study is to point out that the Kaplan-Meier method is not valid to calculate the survival probability or failure probability (risk) in the presence of competing risks and to introduce more valid method of cumulative incidence function. Methods: Survival analysis methods have been widely used in biostatistics division. However the same methods have not been utilized in reliability division. Especially competing risks cases, where several causes of failure occur and the occurrence of one event precludes the occurrence of the other events, are scattered in reliability field. But they are not noticed in the realm of reliability expertism or they are analysed in the wrong way. Specifically Kaplan-Meier method which assumes that the censoring times and failure times are independent is used to calculate the probability of failure in the presence of competing risks, thereby overestimating the real probability of failure. Hence, cumulative incidence function is introduced and sample competing risks data are analysed using cumulative incidence function and some graphs. Finally comparison of cumulative incidence functions and regression type analysis are mentioned briefly. Results: Cumulative incidence function is used to calculate the survival probability or failure probability (risk) in the presence of competing risks and some useful graphs depicting the failure trend over the lifetime are introduced. Conclusion: This paper shows that Kaplan-Meier method is not appropriate for the evaluation of survival or failure over the course of lifetime. In stead, cumulative incidence function is shown to be useful. Some graphs using the cumulative incidence functions are also shown to be informative.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.381-390
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• 2001

In this paper, a new improved crack analysis technique by Element-Free Galerkin(EFG) method is proposed, in which the singularity and the discontinuity of the crack successfully described by adding enrichment terms containing a singular basis function to the standard EFG approximation and a discontinuity function implemented in constructing the shape function across the crack surface. The standard EFG method requires considerable addition of nodes or modification of the model. In addition, the proposed method significantly decreases the size of system of equation compared to the previous enriched EFG method by using localized enrichment region near the crack tip. Numerical example show the improvement and th effectiveness of the previous method.

• Structural Engineering and Mechanics
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• v.7 no.3
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• pp.277-288
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• 1999

This paper presents a fuzzy optimum design of axisymmetrically loaded thin shells of revolution. This paper consists of two parts, namely: an elastic analysis using the new curved element for finite element analysis developed in this study for axisymmetrically loaded thin shells of revolution, and the volume optimization on the basis of results evaluated from the elastic analysis. The curved element to meridian direction is used to develop the computer program. The results obtained from the computer program are compared by exact solution of each analytic example. The fuzzy optimizations of thin shells of revolution are done using [Model 2] which is in the form of a conventional crisp objective function and constraints with non-membership function, and nonlinear optimum GINO (General Interactive Optimizer) programming. In this paper, design examples show that the fuzzy optimum designs of the steel water tank and the steel dome roof could provide significant cost savings.

• PNF and Movement
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• v.18 no.3
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• pp.445-452
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• 2020

Purpose: The purpose of this study was to evaluate the analysis of the association between upper extremity function and the Wolf Motor Function Test (WMFT) for chronic hemiparetic stroke patients and investigate the evidence of the WMFT as a clinical tool of upper extremity function in individuals with chronic hemiparetic stroke. Methods: This study applied an observational, cross-sectional design in outpatients at three local rehabilitation units in Seoul. Forty-nine individuals who had a diagnosis of first stroke participated in this study. All participants were analyzed for four clinical measures, including the Box and Block Test (BBT), the WMFT, grip strength, and the Canadian Occupational Performance Measure (COPM). Results: Upon analysis, a significant relationship was found between the WMFT scores and BBT scores as well as the grip strength. The WMFT score was statistically and positively associated with the COPM satisfaction score; however, it was not related to the COPM performance score. Conclusion: The results of this study suggest that the WMFT is positively related to simple tasks, such as hand muscle strength and manual dexterity. However, the WMFT does not have a relationship with complex tasks, which are measured by COPM performance abilities.

• Fashion & Textile Research Journal
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• v.25 no.3
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• pp.379-385
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• 2023

Recently, with the development of IT technology, interest in mobile applications has increased, and as products and contents that go beyond existing services are released in the beauty industry, interest is steadily increasing. Accordingly, various studies have been conducted, but studies analyzing the functions of beauty applications have been insufficient. Therefore, this study aims to analyze the functions of beauty applications and help in the development and development of future beauty applications. The research method analyzed the functions of beauty applications that have been downloaded more than 100 million through the Google Play Store, and the search period was from October 11, 2020 to November 3, 2020. As a result of the study, it was found that there is a difference in the name of the function, the function being provided, and the application method of the function for each application. As a result of function analysis, a total of 36 functions were classified, and it was analyzed that 30 functions were provided in YCM, 14 functions in YCP, 21 functions in BP, and 10 functions in SS. Therefore, by analyzing the functions of beauty applications through this study, we intend to provide useful data in the future development of beauty applications and help in the development of beauty applications.

• Wind and Structures
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• v.27 no.3
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• pp.149-161
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• 2018

A reliability analysis method is proposed in this paper based on the maximum entropy (MaxEnt) principle in which constraints are specified in terms of the fractional moments instead of integer moments. Then a multiplicative dimensional reduction method (M-DRM) is introduced to compute the fractional moments. The method is applicable for both explicit and implicit limit state functions of complex structures. After two examples illustrate the accuracy and efficiency of this method in comparison to the Monte Carlo simulation (MCS), the method is used to analyze the flutter reliability of suspension bridge. The results show that the empirical formula method in which the limit state function is explicitly represented as a function of variables is only a too conservative estimate for flutter reliability analysis but is not accurate adequately. So it is not suitable for reliability analysis of bridge flutter. The actual flutter reliability analysis should be conducted based on a finite element method in which limit state function is implicitly represented as a function of variables. The proposed M-DRM provide an alternate and efficient way to analyze a much more complicated flutter reliability of long span suspension bridge.

• Journal of the Korean Institute of Educational Facilities
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• v.26 no.6
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• pp.29-37
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• 2019

The research institute has a function to get the research outcome through the various experiments, data collection and analysis. Therefore, research building is important to keep the research condition or experiment environment. But buildings would be deteriorated and leaded into the deterrence of research. Maintenance is planned to protect the research building condition through various general repair or heavy repair. The heavy repair is generally conducted in massive repair scope or main components preparation. In this paper, it aimed at analyzing the effect of the massive or main components repair with inputted cost and its resulted output. In order to analyze the effect of a massive repair, it used the Benefit/Cost analysis and sensitivity analysis. Results of this study are as follows : The benefit/cost analysis shows that research building whose researcher continuously live and study has good effect. On the contrary, pace of the the experimental function is not good effect in benefit/cost analysis. But the experimental function is indispensible to get the research outcom for the research goal. Therefore, the experimental function will be planned to repair and get the historical repair data because the proper repair time would be prepared to cut down the repair cost.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1471-1474
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• 2003

The correlation between the object function and the design parameter is shown on this paper by using the characteristic function for tile mixed result of the structure analysis. tile buckling analysis and the table of orthogonal array according to the original crane's dimensional change. About the above two object functions, the effective of design change according to the change of design parameters could be estimated. Also, the crane's weight is reduced up to 20.58 percent maintaining the structural stability according to the thickness of plate.

• Korean Journal of Mathematics
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• v.28 no.1
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• pp.123-136
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• 2020

In this paper, we give an explicit formula as a rational function for the Ihara zeta function of every finite connected graph without degree one vertices whose circuit rank is two.