• The Korean Journal of Applied Statistics
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• v.21 no.2
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• pp.341-353
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• 2008

The bootstrap method for the score test statistic is proposed in a bivariate negative binomial distribution. The Monte Carlo study shows that the score test for testing overdispersion underestimates the nominal significance level, while the score test for "intrinsic correlation" overestimates the nominal one. To overcome this problem, we propose a bootstrap method for the score test. We find that bootstrap methods keep the significance level close to the nominal significance level for testing the hypothesis. An empirical example is provided to illustrate the results.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.233-245
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• 2009

Availability of pressuremeter test for evaluation of geotechnical properties of foundation soil into which guardrail post is to be installed is investigated in this study. First, an analysis method of the post based on the pressuremeter test is proposed that can obtain bending moment and load-deformation profiles of the post. Then static horizontal load test onto a small scale guardrail post is performed in order to get bearing capacity and load-deformation pattern of the model post. The obtained results are compared with the load-deformation curves and bearing capacity of the post obtained from the pressuremeter method. In addition horizontal impact test to the post is performed using a model bogie car in order to check failure pattern around the model foundation and to investigate dynamic bearing capacity due to deceleration and inertia force of the soil. It is verified that the pressuremeter test is so useful and reasonal technique to analyze road foundation-post interaction.

• Journal of Digital Convergence
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• v.14 no.5
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• pp.227-236
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• 2016

Co-creation is an important approach to innovation that uses internal and external sources for value creation. This study identified the effects of intrinsic motivation, extrinsic motivation, and the moderating effects of activation factors using multiple regression and moderated multiple regression. To this end, 181 usable questionnaires were collected and analyzed. The result of analysis showed that intrinsic motivation had the significant meaning and the moderating effects of activation factors on the relationship between extrinsic motivation and co-creation participation exist. Companies may use this result to activate the co-creation participation of the customer. The future study analyzed by survey responses in multiple layers will improve the generalization of the study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2717-2726
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• 2013

This study was conducted in order to analyze the theories behind external protective factors. In particular, it sought to understand the influence of adolescent resilience on learning motivation. Students of a public high school located in Gyeonggi Province participated in various questionnaires during the week of March 5th, 2013. Frequency analysis, one-way ANOVA (analysis of variance), correlation analysis, and multiple regression analysis were utilized to analyze the acquired data. The results revealed that when family relationships were strong and local community expectations were high, the students' 'attention to implementation processes,' one aspect of intrinsic motivation to learn, was also high. 'Suitable levels of adventurousness and risk-taking,' another aspect of intrinsic motivation to learn, was high when school expectations were also high and when relationships at the school level were weaker. The study results verified that the theory that intrinsic motivation to learn can be enhanced by strengthening external factors to protect adolescent resilience. This study is significant in that it establishes theoretical grounds to address adolescent issues, to develop programs to prevent school dropouts, and to apply the results to future legislative policies.

• The Journal of the Korea Contents Association
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• v.13 no.12
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• pp.276-290
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• 2013

PURPOSE: This study compared the elderly falls and the intrinsic fall risk factors according to gender. METHODS: This descriptive cross-sectional study was a secondary analysis of the data collected for medical checkups for the Transitional Periods of Life supported from the National Health Insurance. The subjects examined were 255,505 people aged 66 years in Korea between January and December, 2008. RESULTS: The elderly people aged 66 when in the transitional periods of life experienced 10.6% of their first falls. The first falls of women (12.4%) was greater than that of men (8.5%) in the elderly. The risk factors for falls included dysuria with an odds ratio of 6.2 to 6.6, depression with an odds ratio of 1.5 to 1.8, gait disturbance with an odds ratio of 1.3 to 1.5, and blindness with an odds ratio of 1.3 to 1.4 in both elderly women and men. CONCLUSIONS: Effective fall prevention should focus on dysuria because it is a more important predictor of falls, even though many intrinsic fall risk factors can affect falls in elderly people.

• The KIPS Transactions:PartB
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• v.10B no.3
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• pp.311-320
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• 2003

The Optimal filter yielding optimal texture feature separation is a most effective technique for extracting the texture objects from multiple textures images. But, most optimal filter design approaches are restricted to the issue of supervised problems. No full-unsupervised method is based on the recognition of texture objects in image. We propose a novel approach that uses unsupervised learning schemes for efficient texture image analysis, and the band-pass feature of Gabor-filter is used for the optimal filter design. In our approach, the self-organizing neural network for multiple texture image identification is based on block-based clustering. The optimal frequency of Gabor-filter is turned to the optimal frequency of the distinct texture in frequency domain by analyzing the spatial frequency. In order to show the performance of the designed filters, after we have attempted to build a various texture images. The texture objects extraction is achieved by using the designed Gabor-filter. Our experimental results show that the performance of the system is very successful.

• 한국전산유체공학회:학술대회논문집
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• 2000.10a
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• pp.129-134
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• 2000

An efficient numerical method to solve the unsteady incompressible Navier-Stokes equations is developed. A fully implicit time advancement is employed to avoid the CFL(Courant-Friedrichs-Lewy) restriction, where the Crank-Nicholson discretization is used for both the diffusion and convection terms. Based on a block LU decomposition, velocity-pressure decoupling is achieved in conjunction with the approximate factorization. Main emphasis is placed on the additional decoupling of the intermediate velocity components with only n th time step velocity The temporal second-order accuracy is Preserved with the approximate factorization without any modification of boundary conditions. Since the decoupled momentum equations are solved without iteration, the computational time is reduced significantly. The present decoupling method is validated by solving the turbulent minimal channel flow unit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1317-1325
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• 2000

A new efficient numerical method for computing three-dimensional, unsteady, incompressible flows is presented. To eliminate the restriction of CFL condition, a fully-implicit time advancement in which the Crank-Nicolson method is used for both the diffusion and convection terms, is adopted. Based on an approximate block LU decomposition method, the velocity -pressure decoupling is achieved. The additional decoupling of the intermediate velocity components in the convection term is made for the fully -implicit time advancement scheme. Since the iterative procedures for the momentum equations are not required, the velocity components decouplings bring forth the reduction of computational cost. The second-order accuracy in time of the present numerical algorithm is ascertained by computing decaying vortices. The present decoupling method is applied to minimal channel flow unit with DNS (Direct Numerical Simulation).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1000-1002
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• 2017

Here, the unsteady Navier-Stokes solver has been developed using implicit dual time stepping method. The implicit dual time stepping method introduced the pseudo time step for solving the new residual including the steady state residual and real time derivative. For the validation of code, Stokes 2nd problem, the laminar flow on the oscillating flat plate was selected and compare the calculating results with analytic solutions. The calculating velocity profile and skin friction has a good agreement with analytic solutions.

• Journal of the Korean Society for information Management
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• v.32 no.2
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• pp.193-219
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• 2015

The focus of traditional evaluations of ontologies is largely performance-based. A comparison of a new ontology with well-established ones, testing of ontologies in different applications, as well as any judgment of an ontology's appropriateness and relatedness to source data heavily rely on what results that ontology seems to manifest. This study, on the other hand, is an attempt to evaluate the quality of a particular ontology as manifested by its structure, representation, and interoperability. To that end, major categories of quality evaluations were first identified through an extensive survey of literature. Evaluation questions were formulated from these categories using the Delphi method and were validated by ontology experts. The entire process produced a set of 53 evaluation questions, which was then employed to test the quality of a newly-developed smartphone ontology.