• Structural Engineering and Mechanics
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• v.76 no.3
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• pp.413-420
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• 2020

Considering inverse cotangential shear strain function, the present paper studies nonlinear stability of nonlocal higher-order refined beams made of metal foams based on Chebyshev-Ritz method. Based on inverse cotangential beam model, it is feasible to incorporate shear deformations needless of shear correction factor. Metal foam is supposed to contain different distributions of pores across the beam thickness. Also, presented Chebyshev-Ritz method can provide a unified solution for considering various boundary conditions based on simply-supported and clamped edges. Nonlinear effects have been included based upon von-karman's assumption and nonlinear elastic foundation. The buckling curves are shown to be affected by pore distribution, geometric imperfection of the beam, nonlocal scale factor, foundation and geometrical factors.

• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.561-571
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• 2012

The MTF(Modulation Transfer Function) is one of quality assesment factors to evaluate the performance of satellite images. Image restoration is needed for MTF compensation, but it is an ill-posed problem and doesn't have a certain solution. Lots of filters were suggested to solve this problem, such as Inverse Filter(IF), Pseudo Inverse Filter(PIF) and Wiener Filter(WF). The most commonly used filter is a WF, but it has a limitation on distinguishing signal and noise. The L-curve-based Modified Wiener Filter(MWF) is a solution technique using a Tikhonov regularization method. The L-curve is used for estimating an optimal regularization parameter. The image restoration was performed with Dubaisat-1 images for PIF, WF, and MWF. It is found that the image restored with MWF results in more improved MTF by 20.93% and 10.85% than PIF and WF, respectively.

• Journal of Sasang Constitutional Medicine
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• v.34 no.1
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• pp.1-12
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• 2022

Objectives This study aimed to examine the differences in the distribution of metabolic syndrome(MetS) and cold hypersensitivity in the hands and feet(CHHF) according to Sasang constitution, and to determine whether CHHF and MetS have an inverse association. Methods MetS and its components, CHHF, Sasang constitution data from 1,998 participants in the Korean medicine Daejeon Citizen Cohort study(KDCC) were obtained. The participants were divided into a non-CHHF(n = 1,270, 63.6%), intermediate(n = 220, 11.0%) and CHHF(n = 508, 25.4%) group according to the thermal sensitivity questionnaire. Sasang constitution was diagnosed by Korea Sasang Constitutional Diagnostic Questionnaire(KS-15). One-way ANOVA and the chi-square test were used for participants' general characteristics and thermal sensitivity and MetS related factors. ANCOVA and logistic regression were used to compare the differences and the odds ratios(ORs) for MetS and its components. Results The MetS and CHHF prevalence rates of the Taeeumin, Soeumin, and Soyangin were 27.6%, 3.8%, 7.7%, and 18.3%, 42.3%, 26.4% respectively. The ANCOVA for MetS components showed that the waist circumference was significantly lower in the CHHF group as compared to the non-CHHF group in total and Soyangin. The logistic regression for MetS prevalence showed that CHHF had a significant inverse association in total(OR = 0.611) and Taeeumin(OR = 0.521). Conclusions The MetS prevalence had the highest in Taeeumin, followed by Soyangin and Soeumin, while the prevalence of CHHF was highest in Soeumin, followed by Soyangin and Taeeumin. In addition, it was confirmed that CHHF and MetS had an inverse association independently.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.81-90
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• 2016

In the civil market, companies launch new products when the acquired innovations are ready, but in defense, customer requests the innovation applied weapon systems. The technology adoption cycle model takes unusual form of market like inverse chasm takes technology inversely. This thesis describes an inverse chasm from the perspective of technology adoption cycle, equipped product model, and technical progress S-curve. As a way to overcome the inverse chasm, considering factors like a self-investment demo model, customer needs, and the temporary chasm expanding phenomenon are derived. And order-effective relationship analysis and chasm marketing strategy are suggested. Especially securing the core technologies and possibility for equipped product by developing self-investment demo model are identified as a good marketing strategy of chasm. This analysis and strategy suggest the policy implications for preemptive advantage of market positioning in the procurement process of defense, discontinuous innovation technology applied on.

• The Korean Journal of Applied Statistics
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• v.37 no.2
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• pp.225-237
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• 2024

In the analysis of competing risks data, some of covariates may not be fully observed for some subjects. In such cases, excluding subjects with missing covariate values from the analysis may result in biased estimates and loss of efficiency. In this paper, we studied multiple imputation and the augmented inverse probability weighting method for regression parameter estimation in the cause-specific proportional hazards model with missing covariates. The performance of estimators obtained from multiple imputation and the augmented inverse probability weighting method is evaluated by simulation studies, which show that those methods perform well. Multiple imputation and the augmented inverse probability weighting method were applied to investigate significant risk factors for the risk of death from breast cancer and from other causes for breast cancer data with missing values for tumor size obtained from the Prostate, Lung, Colorectal, and Ovarian Cancer Screen Trial Study. Under the cause-specific proportional hazards model, the methods show that race, marital status, stage, grade, and tumor size are significant risk factors for breast cancer mortality, and stage has the greatest effect on increasing the risk of breast cancer death. Age at diagnosis and tumor size have significant effects on increasing the risk of other-cause death.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.173-185
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• 2003

This study mainly intends to determine the factors for which dental technicians are satisfied with their jobs and how much the resulting job transfer rate is and thus to identify the correlation between them. For these purpose, 200 subjects were sampled out of dental technicians in Seoul and Incheon, and the survey was performed from July 19, 2002 to August 15 (for 25 days) with self-administered questionnaire. Out of all collected questionnaires, 131 pieces(65.5%) were addressed for this study. As for the tools for this study, the structured questionnaire was used with its proven reliability and feasibility, and the contents of questionnaire consisted of 32 questions on the basis of related references. The contents of questionnaire were categorized into 3 sections: General attribute of subjects; Factors for which dental technicians are satisfied with their jobs; and their intention of job transfer. The questionnaire consisted of total 32 questions which included general attribute of subjects(10 questions), factors of their satisfaction with jobs(17 questions) and intention of job transfer(5 questions). The data analysis was processed by computerized system with SPSS(Statistical Package for Social Sciences). Statistical analysis techniques included frequency, percentage, T-test, F-test analysis and regression analysis. As a result of those analyses, the conclusion can be summarized as follows: 1. As a result of analyzing the factors for which the subjects were satisfied with their jobs, it was found that there were significant differences in career and job title out of question items(P<0.001). It was also shown that the factors of subjects' satisfaction averaged 3.43, which was considerably higher value than I expected. It was found that job and management factors were major job satisfaction factors. 2. As a result of analyzing the intention of subjects to decide their job transfer, it was found that there were significant differences in job title and marital status out of question items(P<0.001). It was shown that the total average of the intention of their job transfer amounted to 3.06. It was shown that dental technicians have relatively higher intention of job transfer from their current work place. 3. It was found that there was inverse correlation between the factors of subjects' satisfaction with their jobs and their intention of job transfer(r=-0.490, P<0.05). Likewise, it was also found that there was inverse correlation mostly between the evaluation value for each independent variable region in term of each factor of job satisfaction and the value for the intention of job transfer. In view of these correlations, it was concluded that higher job satisfaction likely led to lower job transfer. 4. As a result of regression analysis so as to determine the influences of job satisfaction factors on the intention of job transfer, it was found that the highest influential factor was management factor. And it was shown that the test values of model were statistically significant and its explanatory power amounted to 54.6%.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.4
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• pp.355-362
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• 2008

A reliability model of Level II AFDA is proposed to analyze the wave run-up occurring by the interaction of incident waves and sloped coastal structures. The reliability model may be satisfactorily calibrated by Level III Monte-Carlo simulation. Additionally, the partial safety factors of random variables related to wave run-up can be straightforwardly evaluated by the inverse-reliability method that use influence coefficients and uncertainties of random variables, and target probability of failure. In particular, a design equation for wave run-up is derived in the same form as that of deterministic design method so that the reliability-based design method of Level I may be applied easily. Finally, it is confirmed that results redesigned by the reliability-based design method of Level I with partial safety factors suggested in this paper are satisfactorily compared with results of CEM(2006) as well as those of Level II AFDA.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.157-165
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• 2008

Level II AFDA and Level III MCS reliability models are applied to analyze the stability of armor units on trading and coastal harbors in Korea. Hudson's formula and Van der Meer's formula are used in this reliability analysis. Also, probability density functions of reliability index and probability of failure are derived by the additional analysis. In addition, the partial safety factors of all harbors related to armor units can be straightforwardly evaluated by the inverse-reliability method. The upper and lower limits and average level of partial safety factors can be statistically investigated with the results of all cases applied in this paper. Therefore, it may be possible to design armor units of new breakwaters including the uncertainty of random variable and target level by using the present results.

• Journal of Information Technology Applications and Management
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• v.30 no.2
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• pp.19-30
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• 2023

This study aims to analyze service improvement and success factors of electric scooter sharing service companies by using text mining after collecting reviews of shared electric scooter service applications among various models of sharing economy. In this study, the factors of satisfaction and dissatisfaction of service users were identified using the term frequency inverse document frequency (TF-IDF) technique, and topics for each keyword were extracted using the Latent Dirichlet Allocation (LDA) Topic Modeling technique. According to the analysis results, the main topics were entertainment, safety, service area, application complaints, use complaints, convenience, and mobility. Using the analysis results of this study, employees and researchers of electric scooter sharing service companies will be able to contribute to the improvement and success of related services.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.271-276
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• 2012

In humans, N-terminal pro-B-type natriuretic peptide (NT-proBNP) was shown to be inversely related to obesity; in addition, its association with contributing factors for obesity such as insulin, lipids, and glucose profiles has been demonstrated in the literature. However, this association between NT-proBNP and the severity of obesity has not been investigated in veterinary medicine. Our study hypothesis is that plasma levels of NT-proBNP may be related to body condition score (BCS) and contributing factors to obesity in dogs with heart diseases. To achieve our study goal, we collected blood samples from 73 client-owned dogs of small breeds at different stages of heart failure due to chronic mitral valvular insufficiency (CMVI). Fasting glucose concentrations, lipid profiles (i.e., total triglycerides [TG], total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C]), fructosamine, insulin and NT-proBNP concentrations were measured. The insulin/glucose ratio was also determined. NT-proBNP showed not only a significant correlation with the severity of CMVI related heart failure but also an inverse relationship to body condition scores (BCS), insulin plasma levels and fructosamine concentrations. We found the presence of an inverse relationship between plasma levels of NT-proBNP and the severity of obesity. In addition, NT-proBNP was associated with lower levels of contributing factors to obesity such as fructosamine and insulin, creating a possible link between the obesity and NT-proBNP in dogs with heart disease. This is also the first report demonstrating an inverse association between obesity and NT-proBNP in dogs with heart failure.