• Journal of Korea Game Society
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• v.2 no.2
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• pp.46-51
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• 2002

In this study, a real-time simulation method for the phenomena, which are too complex to be simulated during real-time computer games, was proposed based on the neural network. The procedure of proposed method is to 1) obtain correlation data between input parameters and output parameters by mathematical modeling, code analyses, and so on, 2) train the neural network with the correlation data, 3) and insert the trained neural network in a game program as a simulation module. For the case that the number of the input and output parameters is too high to be analyzed, a method was proposed to omit parameters of little importance. The method was successfully applied to severe accidents of nuclear power plants, reflecting that the method was very effective in real time simulation of complex phenomena.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.499-502
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• 2002

We synthesized Y$\sub$1.8/Ba$\sub$2.4/Cu$\sub$3.4/O$\sub$x/(Y123+Y211+1wt% CeO$_2$) powders using Polymeric Complex method and used raw materials; Y$_2$O$_3$, BaCO$_3$, CuO and CeO$_2$. It was formed by calcination at 850 $^{\circ}C$ for 24h in air. In comparison of solid-state method, sol-gel method etc., synthesis temperature decreased up to 100$^{\circ}C$.

• Journal of KSNVE
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• v.6 no.6
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• pp.755-762
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• 1996

An acoustic transmission loss analysis method for mufflers with complex geometry is developed using MSC/NASTRAN on the basis of acoustic-structural analogy and two-microphone method. In this study, mufflers with simple and complex shapes are analyzed using this method and compared with theoretical and experimental results to verify it. Applying this method to design of discharge muffler in a rotary compressor, we obtained 2dB(A) of noise reduction in the range of lower than 1300Hz. Futhermore, adopting this technique for a suction muffler in reciprocal compressor, more than 10dB(A) noise reduction at 500Hz, and in total, 3dB(A) noise reduction is achieved.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.1
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• pp.117-125
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• 2013

Variations of springback in stamped parts are induced by the uncontrollable noises including the variation of incoming material properties, lubrication and other forming process parameters. Reduction of springback variation is very important during springback compensation processes on stamping dies and assembly processes. To reduce the variation of springback, a robust optimization methodology which uses complex method combined with orthogonal array is proposed. The proposed method is applied to the robust design of U-channel die for the reduction of side wall curl. It is shown that the drawbead and die radius of U-channel draw die can be effectively optimized by the proposed method.

• Bulletin of the Korean Mathematical Society
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• v.60 no.5
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• pp.1181-1199
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• 2023

For solving complex symmetric positive definite linear systems, we propose a single step real-valued (SSR) iterative method, which does not involve the complex arithmetic. The upper bound on the spectral radius of the iteration matrix of the SSR method is given and its convergence properties are analyzed. In addition, the quasi-optimal parameter which minimizes the upper bound for the spectral radius of the proposed method is computed. Finally, numerical experiments are given to demonstrate the effectiveness and robustness of the propose methods.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.05a
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• pp.135-135
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• 2001

Mating behavior and reproductivity of male fish were studied as an in vivo screening method of endocrine disruptors. Male medaka (Oryzias latipes) were exposed to 17$\beta$-estradiol at nominal concentrations of 2 and 20 $\mu\textrm{g}$/L for 14 days.(omitted)

• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.408-414
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• 2006

[ $MoSi_2$ ] alloys with Al, B or Nb were prepared by an advanced consolidation process that combined mechanical alloying with pulse discharge sintering (complex forming) to improve the mechanical properties. Their microstructure and mechanical properties were investigated. The $MoSi_2$ alloys fabricated by complex forming method showed very fine microstructure when compared with the sample sintered from commercial $MoSi_2$ powders. Alloys made from powders milled in Ar gas had fewer silica or alumina phases as compared to their counterparts sintered from powders milled in air. In densification of the sintered body, addition of B was more effective than Al or Nb. Both Victors hardness and tensile test indicated that the alloy fabricated by the complex forming method showed better properties than the sample sintered from commercial $MoSi_2$ powders. The Al added alloy sintered from the powders milled in air had the superior mechanical properties due to the suppression of $SiO_2$ and formation of fine $Al_2O_3$ particles.

• Journal of Korean Association for Spatial Structures
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• v.19 no.3
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• pp.33-40
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• 2019

A seismic isolation system is one of the most effective control devices used for mitigating the structural responses due to earthquake loads. This system is generally used as a type of base isolation system for low- and mid-rise building structures. If the base isolation technique is applied to high-rise buildings, a lot of problems may be induced such as the movement of isolation bearings during severe wind loads, the stability problem of bearings under large compression forces. Therefore, a mid-story isolation system was proposed for seismic protection of high-rise buildings. Residence-commerce complex buildings in Korea have vertical irregularity because shear wall type and frame type structures are vertically connected. This problem can be also solved by the mid-story isolation system. An effective analytical method using super elements and substructures was proposed in this study. This method was used to investigate control performance of mid-story isolation system for residence-commerce complex buildings subjected to seismic loads. Based on numerical analyses, it was shown that the mid-story isolation system can effectively reduce seismic responses of residence-commerce complex tall buildings.

• Structural Monitoring and Maintenance
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• v.11 no.2
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• pp.127-148
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• 2024

Estimating cable tension is important in the maintenance of cable structures, such as cable-stayed bridges. In practice, the higher-order vibration method based on natural frequencies is used. In recent years, dampers have been installed onto cables to suppress aerodynamic vibration. Because the higher-order vibration method is suitable to cables without a damper, the damper must be removed before using this method. Because damper removal is time-consuming and labor-intensive, a previous study proposed a tension estimation method for a cable with a damper based on the natural frequencies, which does not require the damper's removal. However, the previous method relies on the modeling accuracy of the damper's complex stiffness. The damper design formula, while intended for design purposes, does not consistently reflect the damper's actual complex stiffness. Therefore, the estimation accuracy deteriorates when the damper's actual complex stiffness deviates from the damper design formula. With this background, this paper introduces a novel tension estimation method based on mode shapes, which circumvents damper modeling errors since mode shapes are independent of the damper's complex stiffness. In the numerical verification using 90 models, the proposed method estimated tension accurately with an estimation error within 0.59%. In the experimental verification, the proposed method estimated tension accurately with an estimation error within 4.17% except for one case, while the previous method had an estimation error of 44% when the damper design formula was used. The proposed method was found to be superior to the previous method in terms of accuracy and practicality by numerical simulation and experiment.

• Transactions of Materials Processing
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• v.16 no.3 s.93
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• pp.187-192
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• 2007

The finite volume method for forging simulation is examined to reveal its possibility as well as its problem in this paper. For this study, the finite volume method based MSC/SuperForge and the finite element method based AFDEX are employed. The simulated results of the homogeneous compression obtained by the two softwares are compared to indicate the problems of the finite volume method while several application examples are given to show the possibility of the finite volume method fur simulation of complex hot forging processes. It is shown that the finite volume method can not predict the exact solution of the homogeneous compression especially in terms of forming load and deformed shape but that it is helpful to simulate very complex forging processes which can hardly be simulated by the conventional finite element method.