• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.3
• /
• pp.146-153
• /
• 2005

Structural design of the torsion beam rear suspension is investigated by calculating warping of the torsion beam. Since the longitudinal displacement in the cross section of the torsion beam due to torsional moment causes normal stress across the beam restrained from outside at both ends, the profile of torsion beam needs to be designed considering the warping. Warping function of the beam is derived with the parameters of cross section fur the arbitrary shapes of torsion beam profiles assuming thin-walled open section. From comparing the warping calculated for two different beam profiles, the design method for the torsion beam in the view point of low stress is discussed. It is shown that the gusset used to reinforce the torsion beam can be optimized in accordance with warping shape. The method to fix the end point of the gusset is proposed to minimize the stress concentrated on the end point of the gusset produced during torsional moment. The result from finite element analysis shows the stress is minimized when the height of gusset end point is coincident with the point where warping of the beam is minimized.

• Transactions of Materials Processing
• /
• v.26 no.3
• /
• pp.156-161
• /
• 2017

In this study, the reason of die fracture occurring in hot forging of an aluminum fixed scroll was studied, based on experiments and finite element predictions. The material is assumed to be rigid-viscoplastic, and the die is rigid for the finite element predictions. The stress in the tension at the wrap root is known to cause brittle fracture, and the increase in the tensile stress is owing to the unbalanced filling of material into the die cavities between both sides of the warp. Based on the empirical and numerical achievements, the effects of geometrical parameters of the material on the die fracture were examined to find practical measures for elongated die life. It has been shown from the parametric study that the material with the optimized trapezoidal cross-section, which can be easily made during cutting or the optimized cylindrical billet with its eccentric placement in the die cavity, can considerably reduce the magnitude of the tensile stress around the die corner fractured, indicating that economical manufacturing with reduced number of stages and elongated die life can be realized at once using the optimized practical initial material.

• Proceedings of the Korean Reliability Society Conference
• /
• 2011.06a
• /
• pp.99-106
• /
• 2011

In this study, the analysis technique, which can estimate the temperature rise and thermal deformation of the ventilated disc considering the vehicle information, braking condition and properties of the disc and pad, is developed. The analytical process of the braking power generation during braking is mathematically derived. The thermal energy, which is applied to the surface of a disc as heat flux, is calculated. Then, the temperature rise and thermal deformation of a disc are estimated using FE software, SAMCEF. Shape of the cross section of the disc is optimized according to the response surface analysis method in order to minimize the temperature rise and thermal deformation. The hot judder analysis is done using the optimized disc, and the analysis results are discussed.

• Journal of Korea Foundry Society
• /
• v.29 no.5
• /
• pp.198-203
• /
• 2009

In order to manufacture copper ultra fine wire used for bonding wire in integrated circuit package, continuous casting process, which can produce high purity copper rod with small cross section, and wiredrawing process have to be optimized to prevent wire brakeage during entire manufacturing process of fine wire. The optimum condition for producing copper rod with mirror surface has to established by investigation of the effects of several parameters such as withdrawal speed, superheat and rod diameter on grain morphology of the cast rod and on its drawing characteristics to fine wire. The purpose of this study is to propose the optimized process parameters in continuous casting process in order to produce cast rod without internal defects, and to predict microstructure orientation suitable for wire drawing process.

• Computers and Concrete
• /
• v.25 no.2
• /
• pp.111-118
• /
• 2020

The construction field must always explore sustainable ways of using its raw materials. Studying the environmental impact generated by reinforced concrete raw materials during their production and transportation can contribute to reducing this impact. This paper initially presents the carbon dioxide emissions from reinforced concrete raw materials, quantified per kilo of raw material and per cubic meter of concrete with different characteristic strengths, for southern Brazil. Subsequently, reinforced concrete elements were optimized to minimize their environmental impact and cost. It was observed that lower values of carbon dioxide emissions and cost savings are generated for less resistant concrete when the structural element is a beam, and that reductions in the cross section dimensions of the beams, sized based on the use of higher strength concrete, may not compensate for the increased environmental impact and costs. For the columns, the behavior differed, presenting lower values of carbon dioxide emissions and costs for higher concrete strengths. The proposed methodology, as well as the results obtained, can be used to support structural projects that have less impact on the environment.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.1
• /
• pp.1-9
• /
• 1998

In this study, we have investigated the preparation conditions of 45$\times$45$\times$20(mm) square cross-section sapphire single crystal by the modified heat exchanger method using water as a coolant. Melting and solidification processes were optimized by the systematic change of the chamber pressure with the heater temperature. As a results, solidification temperature was between 1960 and $1970^{\circ}C$. The crucible was formed by handling. Therefore its shape should had the 'spiral type' ear at edge of its side. Heat exchanger affected to the temperature distribution and gradient of molten alumina. Heat flux and unmelted seed were controlled by volume of heat exchanger. Voids were controlled by the cooling rate of the heater below $0.2^{\circ}C$/min.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.1
• /
• pp.29-36
• /
• 2016

Tensairity girder is a light weight inflatable fabric structural concept which can be used in road emergency transportation. It uses low pressure air to stabilize compression elements against buckling. With the purpose of obtaining the comprehensive target of minimum deflection and weight under ultimate load, the cross-section and the inner pressure of tensairity girder was optimized in this paper. The Variable Complexity Modeling (VCM) method was used in this paper combining the Kriging approximate method with the Finite Element Analysis (FEA) method, which was implemented by ABAQUS. In the Kriging method, the sample points of the surrogate model were outlined by Design of Experiment (DOE) technique based on Optimal Latin Hypercube. The optimization framework was constructed in iSIGHT with a global optimization method, Multi-Island Genetic Algorithm (MIGA), followed by a local optimization method, Sequential Quadratic Program (SQP). The result of the optimization gives a prominent conceptual design of the tensairity girder, which approves the solution architecture of VCM is feasible and efficient. Furthermore, a useful trend of sensitivity between optimization variables and responses was performed to guide future design. It was proved that the inner pressure is the key parameter to balance the maximum Von Mises stress and deflection on tensairity girder, and the parameters of cross section impact the mass of tensairity girder obviously.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.1
• /
• pp.20-28
• /
• 2016

In this study, an efficient method of designing laminate composite radar absorbing structures (RAS) is proposed with consideration given to the structural shape so as to improve aircraft stealth performance. The calculation of the radar cross section (RCS) should be decreased to enhance the efficiency of the stochastic optimization when designing an RAS. In the proposed method, RAS are optimized to match up the input impedance of the minimal RCS, which is obtained by using physical optics and the transmission line theory. Single and double layer dielectric RAS for aircraft wings are employed as numerical examples and designed using the proposed method, RCS minimization and reflection coefficient minimization. The availability of the proposed method is assessed by comparing the similarity of the results and computation time with other design methods. According to the results, the proposed method produces the same results as the stochastic optimization, which adopts the RCS as the objective function, and can improve RAS design efficiency by reducing the number of RCS analyses.

• Journal of the East Asian Society of Dietary Life
• /
• v.22 no.6
• /
• pp.860-867
• /
• 2012

Codonopsis lanceolata serves as, an appetizing health food for its, characteristic flavor, taste, and texture:however, it requires a long and complicated cooking process. Therefore, this study conducted pre-processing procedures to improve the cooking process and Codonopsis lanceolata more easily. For processing efficiency, freezing and blanching were efficient for peeling and the rate of peel disuse. In addition the freezing process, effectively reduced the time spent in beating raw material. In the salinity test, freezing and blanching quickly increased salinity over 28 days. As the result of SEM cross-section tests showed that frozen Codonopsis lanceolata become porous, it's assumed that seasoning permeates into this cross-section efficiently. As the appearance of Deodeok-gui as significant differences according to the pre-processing methods, this study examined pre-processing methods(time spent in peeling, rate of peel disuse, time spent in beating out material, salinity, moisture content, texture, and the color) of Codonopsis lanceolata. After testing Deodeok-gui, it was found that freezing is effective, not only for process efficiency and cooking time reduction, but also for improving its qualities.

• Journal of IKEEE
• /
• v.21 no.3
• /
• pp.288-296
• /
• 2017

The enhancement of photoluminescence of Au-$TiO_2$ nanoparticles by surface plasmon resonance has been studied extensively by experiment in recent years. For the purpose of optimizing the photoluminescence property of Au-$TiO_2$ nanoparticles, the manufacturing parameters related to the Au nanoparticles and $TiO_2$ nanoparticles need to be considered. In this paper, Drude model and Maier's effective volume method are used to analyze the variation of the metal nanoparticle radius, separation between metal nanoparticle and dielectric molecule, and total absorption cross-section with original radiative efficiency on the photoluminescence property of Au-$TiO_2$ nanoparticles. The results show that to obtain the optimized enhancement factor for photoluminescence process, the size of Au nanoparticle is about 13 - 20 nm, the separation between Au nanoparticle and $TiO_2$ molecule is about 5 -15 nm, the total absorption cross-section of $TiO_2$ molecules is about $1-100nm^2$ and the original radiative efficiency of $TiO_2$ molecule is weak about 0.001- 0.1. With these fabrication parameters, the photoluminescence property of Au-$TiO_2$ nanoparticles can be enhanced several thousand times compared to traditional $TiO_2$ nanoparticles.