• Journal of Advanced Marine Engineering and Technology
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• 제26권5호
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• pp.589-595
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• 2002

Fluid mixing is ubiquitous and essential in many natural and industrial systems. Understanding the mixing processes that occur in these diverse systems is essential for predicting many aspects of practical importance. The objective of this study was to develop a new mixing element and to perform the experimental investigation of flow and mixing in a static mixer that is equipped the new element and the others. Glycerin and gear oil were used as mixing fluids. Pressure drops across the static mixer elements of different designs and different numbers were measured using a hydraulic manometer The axial and cross-sectional views of tracer mixing were photographed using a digital camera. The pressure drops of SSM mixer were about 20% less than that of Sulzer mixer whereas the mixing performance of SSM mixer was not so good as that of Sulzer mixer

• 대한수학회논문집
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• 제10권3호
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• pp.653-659
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• 1995

We prove that two essentially normal elements of a type $II_{\infty}$ factor von Neumann algebra are unitarily equivalent up to the compact ideal if and only if they have the identical essential spectrum and the same index data. Also we calculate the spectrum and essential spectrum of a non-unitary isometry of von Neumann algebra.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.787-790
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• 1997

This paper proposes a method which selects essential elements in a human evaluation model using the Choquet integral based on fuzzy measures, and applies the model to the evaluation of human interface. Three kinds of concepts are defined to select essential elements. Increment Degree implies the increment degree from fuzzy measures of composed elements to the fuzzy measure of a combined element. Average of Increment Degree of an element means the relative possibility of superadditivity of the fuzzy measure of each combined element. Necessity Degree means the selection degree of each combined element as a result of the human evaluation. A task experiment, which consists of a static work and two dynamic works, is performed by the use of some human interfaces. In the experiment, (1) a warning sound which gives an attention to subjects, (2) a color vision which can be distinguished easily or not, (3) the size of working area and (4) a response of confirmation that is given from an interface, are considered as human interface elements. Subjects answer the questionnaire after the experiment. From the data of the questionnaire, fuzzy measures are identified and are applied to the proposed model. Effectiveness of the proposed model is confirmed by the comparison of human interface elements extracted from the proposed model and those from the questionnaire.

• KIEAE Journal
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• 제16권1호
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• pp.47-55
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• 2016

Purpose: Long-life housing causes unavoidable cost increase while providing higher durability, flexibility, and repair easiness compare to those of normal apartment. The effectiveness should be evaluated considering the level of passing mandatory Long-life housing Certification System when supplying specific size of apartment complex. Thus, it is essential to identify the estimated costs and the obtainable grade by applying the optional element technologies selectively during the design phase. This study aimed to suggest the technology influence matrix(TIM) to support decision-making of element technologies in planning stage of long-life housing. Method: The technology influence matrix was established based on the property information about applicable element technologies for long-life housing such as construction methods, interface types, cost data, and certification-related characteristics. The usefulness of TIM was verified through case study, in which TIM was applied to the exclusive housing unit and the influences from four areas of quantity, cost, certification, and schedule were identified and calculated. Result: TIMs covering four areas representing the essential planning factors were developed, and are expected to contribute to sound decision-making in planning long-life housing.

• 섬유기술과 산업
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• 제2권3호
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• pp.330-332
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• 1998

• Nuclear Engineering and Technology
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• 제41권5호
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• pp.649-654
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• 2009

The finite element based lattice Boltzmann method (FELBM) has been developed to model complex fluid domain shapes, which is essential for studying fluid-structure interaction problems in commercial nuclear power systems, for example. The present study addresses a new finite element formulation of the lattice Boltzmann equation using a general weighted residual technique. Among the weighted residual formulations, the collocation method, Galerkin method, and method of moments are used for finite element based Lattice Boltzmann solutions. Different finite element geometries, such as triangular, quadrilateral, and general six-sided solids, were used in this work. Some examples using the FELBM are studied. The results were compared with both analytical and computational fluid dynamics solutions.

• Geomechanics and Engineering
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• 제4권3호
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• pp.173-190
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• 2012

With recent growing interests in the Performance-Based Seismic Design and Assessment Methodology, more realistic modeling of a structural system is deemed essential in analyzing, designing, and evaluating both newly constructed and existing buildings under seismic events. Consequently, a shallow foundation element becomes an essential constituent in the implementation of this seismic design and assessment methodology. In this paper, a contact interface fiber section element is presented for use in modeling soil-shallow foundation systems. The assumption of a rigid footing on a Winkler-based soil rests simply on the Euler-Bernoulli's hypothesis on sectional kinematics. Fiber section discretization is employed to represent the contact interface sectional response. The hyperbolic function provides an adequate means of representing the stress-deformation behavior of each soil fiber. The element is simple but efficient in representing salient features of the soil-shallow foundation system (sliding, settling, and rocking). Two experimental results from centrifuge-scale and full-scale cyclic loading tests on shallow foundations are used to illustrate the model characteristics and verify the accuracy of the model. Based on this comprehensive model validation, it is observed that the model performs quite satisfactorily. It resembles reasonably well the experimental results in terms of moment, shear, settlement, and rotation demands. The hysteretic behavior of moment-rotation responses and the rotation-settlement feature are also captured well by the model.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.504-512
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• 2003

Simulation programs have been developed and used as an attempt to improve the accuracy of Non-Destructive Evaluation(NDE) techniques. The applicability of these programs is very limited, however, because it is difficult to describe the delicacy of the propagation of stress waves. To investigate the applicability of the finite element analysis for stress wave-based NDE techniques numerical simulation for Impact-Echo method and SASW method is performed. The numerical studies are performed to determine the essential parameters such as contact time of impact load, mesh size and time step size. These studies show that the choice of parameter is very important for improving the accuracy and confidence of the numerical procedure and, thereby, the applicability of the numerical analysis for stress wave-based NDE techniques

• Structural Engineering and Mechanics
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• 제21권3호
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• pp.315-332
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• 2005

The Element-free Galerkin Method has become a very popular tool for the simulation of mechanical problems with moving boundaries. The internally applied Moving Least Squares interpolation uses in general Gaussian or cubic weighting functions and has compact support. Due to the approximative character of this interpolation the obtained shape functions do not fulfill the interpolation conditions, which causes additional numerical effort for the application of the boundary conditions. In this paper a new weighting function is presented, which was designed for meshless shape functions to fulfill these essential conditions with very high accuracy without any additional effort. Furthermore this interpolation gives much more stable results for varying size of the influence radius and for strongly distorted nodal arrangements than existing weighting function types.

• International Journal of Railway
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• 제5권4호
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• pp.152-155
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• 2012

The essential element of brake device for railway vehicle is in demand for higher performance along side the trend of railway vehicle size and speed. Essential element of brake device for high speed train is composed of metallic friction material and brake disc. Thus, brake distance, duration and brake stability shall be determined due to friction materials and friction characteristics. Also friction characteristics are influenced by metallic friction material's properties of matter, manufacturing process and component parts. Various materials and configurations of metallic friction materials are currently being implemented to railway vehicles, For this reason study of friction characteristics in accordance with materials is necessary, but study of these important elements are not actively being accomplished. Therefore, in this study, wished to study the graphite's friction characteristic comprised in friction material in accordance with particle size and amount of volume through lab-scale test.