• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.2B
• /
• pp.209-216
• /
• 2006

This study is to analyse the characteristics of bar migration, which is important roles to bank erosion and meandering development, for the meandering channels with erodible bed by using a 2-D numerical model in the generalized coordinate systems. The results of the numerical experiments showed that the features of bar migration were affected by the meandering wavelength to the width ratio, and had a relatively good agreement with the criterion for bar migration through a bend suggested by Kinoshita and Miwa (1974). The bar migrated with speed in the channel with long wavelength and broad width, and the criterion for bar migration was increased. The bar celerity was decreased abruptly near the criterion.

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.39-42
• /
• 2004

Turbo codes, proposed by Berrou, that increase the interleaver size and the number of iteration have better than conventional convolutional codes, in case of BER performance. However, because turbo codes has been required much decoding delay to increase iteration number, it demands unnecessary iterative decoding. Therefore, in this paper, we propose iterative decoding stop criterion that uses the variance of absolute value of LLR. This algorithm can be reduced average iterative decoding number and had lossless performance of BER, because of decreasing unnecessary iterative decoding.

• Research in Mathematical Education
• /
• v.8 no.4
• /
• pp.261-277
• /
• 2004

Julia sets, their variants and generalizations have been studied extensively by using the Picard iterations. The purpose of this paper is to introduce Mann iterative procedure in the study of Julia sets. Escape criterions with respect to this process are obtained for polynomials in the complex plane. New escape criterions are significantly much superior to their corresponding cousins. Further, new algorithms are devised to compute filled Julia sets. Some beautiful and exciting figures of new filled Julia sets are included to show the power and fascination of our new venture.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.6 no.2
• /
• pp.13-19
• /
• 1981

This paper developed 3 flow-shop sequencing heuristic methods: modified RA method, modified RACS method and modified RAES method. These methods modified RA method, RACS method and RAES method developed by D. G. Dannenbring. These methods can easily determine desirable sequence of orders and can improve nx3 flow-shop's productivity and efficiency. The maximum flow-time criterion is selected as the evaluation criterion of flow-shop's efficiency, We evaluated these 6 heuristic methods’ performance. By the evaluation of the result, we can see that the modified methods produce a shorter maximum flow-time than the original methods.

• Journal of Korean Institute of Industrial Engineers
• /
• v.12 no.2
• /
• pp.89-99
• /
• 1986

The study attempts to estimate and evaluate the rates of return on graduate degree holders who major in science and engineering. The model of this study adopts the rate of return method considering unemployment as well as mortality rate. The data are collected by questionnaires and interviews. The results show that the social rate of return(SROR) of bachelors is lower than the rate of return on investment in physical capital which is assumed as a decision criterion of public investment in Korea, but the SROR of Ph.D. holders is balanced. The results also show that the private rates of return (PROR) of all the levels in postgraduate science and engineering education are higher than the private discount rate which is a decision criterion of private investment in Korea. It also indicates that the PROR on investment in graduate education is not likely higher than the SROR because an individual bears high share of the educational costs.

• Proceedings of the IEEK Conference
• /
• 2003.11a
• /
• pp.505-508
• /
• 2003

The current paper proposes a new vertex selection scheme for polygon-based contour ceding. To efficiently characterize the shape of an object, we incorporate the curvature information in addition to the conventional maximum distance criterion in vertex selection process. The proposed method consists of “two-step procedure.” At first, contour pixels of high curvature value are selected as key vertices based on the curvature scale space (CSS), thereby dividing an overall contour into several contour-segments. Each segment is considered as an open contour whose end points are two consecutive key vertices and is processed independently. In the second step, vertices for each contour segment are selected using progressive vertex selection (PVS) method in order to obtain minimum number of vertices under the given maximum distance criterion ( $D_{MAX}$). Experimental results are presented to compare the approximation performances of the proposed and conventional methods.s.

• Steel and Composite Structures
• /
• v.16 no.5
• /
• pp.533-557
• /
• 2014

In this study, the performances of the SMRF building equipped with energy dissipating devices are studied. Three types of these structures with different heights are considered. The Added Damping and Stiffness (ADAS) devices are used as energy dissipating devices in these structures. The behavior of these structures with ADAS devices subjected to near source ground motions are investigated. Three SMRF buildings with five, ten and fifteen-story, with ADAS devices were chosen. The nonlinear time history analysis was used by applying the near source ground motions with PERFORM 3D.V4 and conclusions are drawn upon an energy criterion. The effect of PGA variation and height of the frames are also considered based on the energy criterion.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1994.03b
• /
• pp.3-12
• /
• 1994

Based on the shear failure mechanism, hydraulic fracturing criteria are extended to three dimensional stress state. According to the situation of the directions of borehole and major principal stress axes, three equations can be derived for three dimensional hydraulic fracturing problems. By comparing these equations, a single criterion is selected for hydraulic fracturing pressure in cohesive soils. The criterion is a function of maximum principal stress, minimum principal stress and soil parameters in UU conditions. The equation indicates that with any increase in maximim principal stress, hydraulic fracturing pressure decreases. In order to prove the integrity of the criteria, laboratory tests are performed on compacted cubical specimens using true a triaxial apparatus. The shape and direction of fractures are determined by injecting colored water after fracture initiation. It is found that the direction of fractures are perpendicular to the o1 plane.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.5
• /
• pp.453-459
• /
• 2008

In general, reliability of AHP depends on pairwise comparison of evaluators. In addition, human judgment on the importance of alternatives or criteria is always imprecise and vague. The Fuzzy AHP technique is suggested and used widely recently. In this paper, we prioritize future energy technology development for well focused R&D. We selected 3 criteria and 10 sub-criteria. According to the result in this study, the most important sub-criterion is the precedence over other competitive technology, the second is the possibility for fundamental technology acquisition, and the third is the improvement energy efficiency. The other side, the lowest important sub-criterion is the technology level compared with advanced countries.

• Transactions of Materials Processing
• /
• v.5 no.1
• /
• pp.72-80
• /
• 1996

During the shape rolling process the influence of reduction ration and taper of shape roller on deformation and limit of ductile fracture such as free surface cracks developing in the workpiece has been studied. The deformation behaviours were analyzed by the 3-dimensional elasto-pastic finite element method and the conditions of ductile fracture were determined from 3-dimensional elasto-plastic finite element method and modified Cockrogt-Latham criterion. The deformed geometry and prediction of ductile fracture by 3-dimensional elasto-plastic finite element method are compared with experimental results The calcuated results are in good agreements with experimental data. The analysis used in the study was found to be effective in predicting the shape rolling process.