• Journal of the Korean Operations Research and Management Science Society
• /
• v.34 no.2
• /
• pp.77-90
• /
• 2009

Total profit level Increases if a company increase the cost for achieving R&D related goals of equipment productivity enhancement, production cost saving, or for achieving equipment scale target, sales volume goal. But how much money should be invested to achieve a certain level of profit? We formulated the model to set the optimal goal levels to minimize the investment cost under the constraint that certain level of total profit should be guaranteed. This model derived from a case of P steel company. We found that this should be considered in relation with the production sales planning (known as optimal product mix problem) to guarantee the profit. We suggested a nonlinear programming model, 3 valiant form of the p+roduct mix problem. We can find the optimal Investment level for the R&D related goals or sales volume goal, equipment scale target for the P steel company using the model.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1993.04a
• /
• pp.65-72
• /
• 1993

Steel fiber reinforced concrete(SFRC) which is made by short, randomly distributed steel fibers in concrete is superior in its tensile mechanical properties to plain concrete in enhancement of tensile strength and tensile ductility. These improvements are attributed to crack arresting mechanism and formation of longer crack paths due to fibers , which as a consequence lead to increase in energy absorption capacity of SFRC. In the post-peak region under tensile stresses, major macrocrack forms at critical section. The opening of this macrocrack is mainly resisted by both of the fiber pull-out bridging the cracked surfaces and the resistance by matrix softening. In this study, micromechaincal approach has been made in order to simulate tensile behavior of SFRC and based on which the theoretical model is presented. This model reflects the features of both the composite material concept and the spacing concept in predicting tensile strength of SFRC. The model also takes into account for the effects of matrix tensile softening and fiber bridging by pull-out on the resistance for the post-peak behavior of SFRC. It has been shown that the developed model satisfactory predicts the experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.375-378
• /
• 2003

In the present study, a new approach to predict the strength of sintered materials has been carried out and a new framework combining neck growth model and ideal pore model has been established based on the results of tensile tests on powder injection molded specimens with the various porosity. Powder injection molding (PIM) uses the shaping advantage of injection molding but is applicable to metals and ceramics. PIM delivers structural materials in a shaping technology previously restricted to polymers. 17-4 PH stainless steel powders with average diameters of 10 $\mu\textrm{m}$ were injection-molded into flat tensile specimens sintered at the various temperatures ranging from 900 to 1350$^{\circ}C$ for 1h. The relationships between strength and porosity were applied to the experimental results and verified.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.601-606
• /
• 1993

From the power plants in a steel plant, environment pollutants such as SOx, NOx, CO are emitted by the combustion reaction between the fuels those are by-product gases and oil. To reduce the amounts of the pollutants, it must be important that build the predictive models for the emission of the pollutants. In this paper, the model that predict the amount of future fuel consumption and the model that predict the amount of generated pollutants for the used fuel amounts is developed by using Gibb's free energy minimization method with the temperature correction techniques and neural network back propagation method. For some data set, the calculation results from this models are compared with the real emission amounts of SOx, NOx and result of the calculation by the ASPEN plus which is a commercial software. The result from this model is better than the result by ASPEN plus for this problem.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.81-84
• /
• 2008

The purposes of this study are to verify a reasonable model of material characteristic and to propose a rational model of reinforcement characteristic considering monotonic and cyclic loading about manufactured reinforcing steel in Korea. Longitudinal reinforcements of the plastic hinge region were behaved tensile deformation and compressional deformation by direction of lateral loading. However Confinement steels were behaved only tensile deformation by lateral loading. Transverse steels were laid the state of tension in the lateral loading of time, and they were laid state that stress is zero when it was removed lateral load. The tests for cyclic tension loading were performed for test variable as yield strength and reinforcement bar sizes. It was estimated that the total strain energy per unit volume was 74 $MJ/m^3$. The modified ultimate concrete compression strain model was proposed based on experimental study of cyclic tension test for manufactured reinforcing steel in Korea.

• Computers and Concrete
• /
• v.1 no.4
• /
• pp.417-432
• /
• 2004

An analytical model which can simulate the post-cracking nonlinear behavior of reinforced concrete (RC) members such as bars and panels subject to uniaxial and biaxial stresses is presented. The proposed model includes the description of biaxial failure criteria and the average stress-strain relation of reinforcing steel. Based on strain distribution functions of steel and concrete after cracking, a criterion to consider the tension-stiffening effect is proposed using the concept of average stresses and strains. The validity of the introduced model is established by comparing the analytical predictions for reinforced concrete uniaxial tension members with results from experimental studies. In advance, correlation studies between analytical results and experimental data are also extended to RC panels subject to biaxial tensile stresses to verify the efficiency of the proposed model and to identify the significance of various effects on the response of biaxially loaded reinforced concrete panels.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.04a
• /
• pp.153-160
• /
• 2003

Nonlinear finite element analysis of reinforced concrete panels subjected to biaxial tensile loads are carried out by using a 9-node assumed strain shell element. The present study mainly focuses on the performance evaluation of material models such as cracking criteria, tension stiffening model and steel model in the membrane energy dominant situation. From numerical results, the exponential form of tension stiffening model together with the use of average yield stress model for the steel embedded in the concrete performs well in the panel analysis under biaxial tensile loading condition and it produces a good agreement with experiment results. Finally, the present results are provided as a benchmark test for reinforced concrete panel structures.

• Computers and Concrete
• /
• v.19 no.4
• /
• pp.375-385
• /
• 2017

In the present paper experimental and numerical analysis of hook-ended steel fiber reinforced concrete is carried out. The experimental tests are performed on notched beams loaded in 3-point bending using fiber volume fractions up to 1.5%. The numerical analysis of fiber reinforced concrete beams is performed at meso scale. The concrete is discretized with 3D solid finite elements and microplane model is used as a constitutive law. The fibers are modelled by randomly generated 1D truss finite elements, which are connected with concrete matrix by discrete bond-slip relationship. It is demonstrated that the presented approach, which is based on the modelling of concrete matrix using microplane model, able to realistically replicate experimental results. In all investigated cases failure is due to the pull-out of fibers. It is shown that with increase of volume content of fibers the effective bond strength and slip capacity of fibers decreases.

• Transactions of Materials Processing
• /
• v.26 no.3
• /
• pp.162-167
• /
• 2017

The tensile surface residual stress in the multi-pass drawn wire deteriorates the mechanical properties of the wire. Therefore, the evaluation of the residual stress is very important. Especially, the axial residual stress on the wire surface is the highest. Therefore, the objective of this study was to propose an axial surface residual stress prediction model of the multi-pass drawn steel wire. In order to achieve this objective, an elastoplastic finite element (FE) analysis was carried out to investigate the effect of semi-die angle and reduction ratio of the axial surface residual stress. By using the results of the FE analysis, a surface residual stress prediction model was proposed. In order to verify the effectiveness of the prediction model, the predicted residual stress was compared to that of a wire drawing experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1417-1420
• /
• 2006

In this paper, floor impact is studied by using 1-D wave model and predicted insertion loss is compared to the measurements done in the mock-up. A mock-up is built by using 6t steel plate, and two identical cabins are made where 25t or 50t panel is used to construct wall and ceiling inside the steel structure. Various floating floor structures are studied, in which mineral wool thickness, height, and stiffness changes are investigated. It is shown that the wave model and measurements are in good agreements in general, although there occur significant discrepancies in the low frequency range below 200 Hz.