• Proceedings of the KSR Conference
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• 2004.06a
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• pp.915-920
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• 2004

We have studied the technologies for a double-deck train. But, there are no standards and test methods for a double-deck train. Therefore, we apply the standard and test method of the general train to transform the structural analysis of a double-deck train. This study is the result of a structural analysis by the finite element method for double-deck train carbodies. The results of the study can be used as basic guidelines in designing double-deck trains in the future.

• Journal of the Chungcheong Mathematical Society
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• v.30 no.1
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• pp.1-13
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• 2017

We introduce the concepts of (${\mathcal{T}}^{{\mu}{\gamma}},{\mathcal{U}}^{{\mu}{\gamma}}$)-double (r, s)(u, v)-preclosures and (${\mathcal{T}}^{{\mu}{\gamma}},{\mathcal{U}}^{{\mu}{\gamma}}$)-double (r, s)(u, v)-preinteriors. Using the notions, we investigate some of characteristic properties of double pairwise (r, s)(u, v)-precontinuous mappings.

• Communications for Statistical Applications and Methods
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• v.16 no.5
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• pp.859-870
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• 2009

We obtain a skewed double Weibull distribution by a double Weibull distribution, and evaluate its coefficient of skewness. And we obtain the approximate maximum likelihood estimator(AML) and moment estimator of skew parameter in the skewed double Weibull distribution, and hence compare simulated mean squared errors(MSE) of those estimators. We compare simulated MSE of two proposed reliability estimators in two independent skewed double Weibull distributions each with different skew parameters. Finally we introduce a skewed double Weibull distribution generated by a uniform kernel.

• Journal of the Chungcheong Mathematical Society
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• v.30 no.4
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• pp.423-433
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• 2017

We introduce the concepts of double strongly (r, s)(u, v)-semiopen sets, double strongly (r, s)(u, v)-semiclosed sets and double pairwise strongly (r, s)(u, v)-semicontinuous mappings in double bitopological spaces and investigate some of their characteristic properties.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.6
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• pp.677-682
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• 2006

Statement of problem. Various double crown systems have been used with removable partial dentures in the clinical field. Although retentive force between inner and outer crown are affected by several factors, differences between the retentive forces of different double crown system types are expected. Purpose. The purpose of this study was to evaluate the initial retentive force of outer crowns fabricated by the conventional casting technique in conus and hybrid double crowns. Material and methods. Ten double crowns were fabricated. The groups were as follows. Group 1, double crowns of hybrid inner and outer crowns using the conventional casting method; Group 2, double crowns of conus inner and outer crowns using the conventional casting method. Tensile strengths of double crowns when the inner and outer crowns were separated on a universal testing machine were measured. These values of retentive force were then statistically analyzed using the Kruskal-Wallis test. Results. Retentive force in group 2 was significantly higher than that in group 1(p<.05). Conclusion. The initial retentive forces of double crowns were affected by the types of the double crown system.

• Journal of the Korean Home Economics Association
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• v.44 no.6 s.220
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• pp.47-58
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• 2006

This research focused on the family stress and family strengths in double-income couples. The subjects of this study were 171 double-income couples, in the Kyeongnam Area, Korea. The major findings from the study are as follows. 1) The degree of family stress of the husband and wife in double-income couples was 2.90 and 2.97, respectively, on a scale of 0-5.0. The significant variables were economic level, self-esteem and marital satisfaction in double-income couples' husband, and having a housework-helper, job satisfaction, self-esteem and marital satisfaction in double-income couples' wife. 2) The degree of family strengths of the husband and wife in double-income couples was 3.84 and 3.82, respectively, on a scale of 0-5.0. The significant variables were job satisfaction, self-esteem and marital satisfaction in double-income couples' husband, and the educational level, job type, self-esteem and marital satisfaction in double-income couples' wife. 3) There was a close inverse correlation between the lamely stress and family strengths in the husband and wife of double-income couples.

• Bulletin of the Korean Mathematical Society
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• v.60 no.2
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• pp.443-460
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• 2023

A binary linear code is said to be a ℤ₂-double cyclic code if its coordinates can be partitioned into two subsets such that any simultaneous cyclic shift of the coordinates of the subsets leaves the code invariant. These codes were introduced in [6]. A ℤ₂-double cyclic code is called reversible if reversing the order of the coordinates of the two subsets leaves the code invariant. In this note, we give necessary and sufficient conditions for a ℤ₂-double cyclic code to be reversible. We also give a relation between reversible ℤ₂-double cyclic code and LCD ℤ₂-double cyclic code for the separable case and we present a few examples to show that such a relation doesn't hold in the non-separable case. Furthermore, we list examples of reversible ℤ₂-double cyclic codes of length ≤ 10.

• Kyungpook Mathematical Journal
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• v.54 no.1
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• pp.143-153
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• 2014

The notion of double-framed soft filters of a CI-algebra is introduced, and related properties are investigated. Further characterization of a double-framed soft filter is considered, and conditions for a double-framed soft set to be a double-framed soft filter are provided. Finally a new double-framed soft filter from old one is established.

• Earthquakes and Structures
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• v.27 no.1
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• pp.17-29
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• 2024

The traditional double story isolated structure is a derivative of the base isolated and inter-story isolated structures, while the new double story isolated structure represents a novel variation derived from the traditional double story isolated structure. In order to investigate the seismic response of the new double story isolated structure, a comprehensive structural model was developed. Concurrently, models for the basic fixed, base isolated, inter-story isolated, and traditional double story isolated structures were also established for comparative analysis. The nonlinear dynamic time-history response of the new double story isolated structure under rare earthquake excitations was analyzed. The findings of the study reveal that, in comparison to the basic fixed structure, the new double story isolated structure exhibits superior performance across all evaluated aspects. Furthermore, when compared to the base isolated and inter-story isolated structures, the new double story isolated structure demonstrates significant reductions in inter-story shear force, top acceleration, and inter-frame displacement. The horizontal displacement of the new double story isolated structure is primarily localized within the two isolation layers, effectively dissipating the majority of input seismic energy. In contrast to the traditional double story isolated structure, the new design minimizes displacements within the inter-isolation layer situated in the central part of the frame, as well as mitigates the overturning forces acting on the lower frame column. Consequently, this design ensures the structural integrity of the core tube, thereby preventing potential collapse and structural damage.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.6
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• pp.1872-1879
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• 2015

The present study was conducted on the improvement of the heat transfer performance of double pipe heat exchangers with helical insert device. Double pipe heat exchangers with helical insert device were studied for improvement of the heat transfer performance of double pipe heat exchangers with helical insert device and plain double pipe heat exchangers were also studied to comparatively analyze heat transfer performance. Experimental results were derived on changes in the Reynold's numbers of the cooling water flowing in helical and plain double pipe heat exchangers and changes in the heat flux of the air. Thereafter, to verify the reliability of the experimental results, the theoretical total energy and the experimental total energy were comparatively analyzed and the following results were derived. The thermal energy of the calorie lost by the hot air and that of the calorie obtained by the cooling water were well balanced. The experiments of plain double pipe heat exchangers and double pipe heat exchangers with helical insert device were conducted under normal conditions and the theoretical overall heat transfer coefficient value and the experimental overall heat transfer coefficient value coincided well with each other. In both plain double pipe heat exchangers and double pipe heat exchangers with helical insert device, heat transfer rates increased as the cooling water flow velocity increased. Under the same experimental conditions, the heat transfer performance of double pipe heat exchangers with helical insert device was shown to be higher by approximately 1.5 times than that of plain double pipe heat exchangers.