• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.177-182
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• 2007

In this paper, automotive hydraulic pipeline systems are modeled in which a straight blocked pipe, two pipes with sudden expansion or contraction are connected in series and terminated with a chamber. The frequency response characteristics of these composite pipeline systems are investigated experimentally. The theoretical analysis for various pipe configurations is base on transfer matrix method with frequency dependent viscous friction distributed parameter pipeline model. The gain and phase of transfer functions are included for comparison with experimental results. There is close agreement between the results of experimental and theoretical determination of pressure response in automotive hydraulic pipeline systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.397-402
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• 2007

Application of hydroforming technology for Engine Cradle has done much to reduce the weight of it. In most cases, hydroformed member of Engine Cradle is made in one-piece. And this method cause a limeted design that amount of expansion at the center portion of the member is not enough to meet the required performance. This limited design leads to decrease the dynamic characteristics of Engine Cradle. In this paper, comparative analyses of conventional stamped engine cradle and hydroformed cradle of one-piece were conducted using Normal Mode analysis and FRF(Frequancy Response Function)analysis. Finally, to improve the disadvantage mentioned above, hydroformed member of 3-pieces was proposed.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.96-101
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• 2011

Under extreme test or operation condition, refrigerator endures complicated stresses state and thermal bowing deformation arises on the sidewall. Shelf rails designed in the inner case provide increased surface area to permit expansion without bowing, and also increase structural rigidity to resist bowing. In this study, we designed six different shelf patterns of refrigerator model and studied the bead on refrigerator deformation using finite element method (FEM). Analysis result shows that increasing the numbers of beads properly in refrigerator is more helpful to reduce thermal bowing deformation. In addition, the beads would decrease stress on refrigerator sidewall. However, vertical beads have no effect to reduce thermal deformation of the bowing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.361-365
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• 2002

This research is presented for optimizing the coefficients of spring and damper by impulse which is applied to AGV when the two containers are loaded on AGV. The suspension is estimated to the condition that two containers, initial velocity of container, initial height of container and maximum of suspension stroke. The coefficients of spring and damper are calculated numerically through Newmark method uses finite difference expansions. The procedure of calculation is applied by one DOFs of mass-spring-damper system. The coefficients of spring and damper have large value as increase of height or decrease of stroke. The result of calculation is shown in graph and the investigation is used AGV design.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.660-665
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• 1993

An elastic model is developed to predict the average thermal residual stresses in the matrix and fiber of a misoriented short fiber composite. The thermal residual stresses are induced by the mismatch in the coefficient of the thermal expansion of the matrix and fiber when the composite is subjected to a uniform temperature change. The model considers two special cases of fiber misorientation ; two-dimensional in-plane and three-dimensional axisymmetric. The analytical formulation of the model is based on Eshelby's equivalent inclusion method and is nuque in that it is able to account for interactions among fibers. The model is more general than past models and it is able to treat prior analyses of the simpler composite systems as extram cases. The present model is to investigate the effects of fiber volume fraction, distribution type, distribution cut-off angle, and aspect ratio on thermal residual stress for both in-plane and axisymmetric fiber misorientation. Fiber volum fraction, aspect ratio, and disturbution cut-off angle are shown to have more significant effects on the magnitude of the thermal residual stress than fiber distrubution type for both in-plane and axisymmetric misorientation.

• Communications for Statistical Applications and Methods
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• v.27 no.1
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• pp.149-161
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• 2020

In this paper we extend the functional principal component analysis for real-valued random functions to the case of Hilbert-space-valued functional random objects. For this, we introduce an autocovariance operator acting on the space of real-valued functions. We establish an eigendecomposition of the autocovariance operator and a Karuhnen-Loève expansion. We propose the estimators of the eigenfunctions and the functional principal component scores, and investigate the rates of convergence of the estimators to their targets. We detail the implementation of the methodology for the cases of compositional vectors and density functions, and illustrate the method by analyzing time-varying population composition data. We also discuss an extension of the methodology to multivariate cases and develop the corresponding theory.

• Korean Journal of Microbiology
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• v.11 no.4
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• pp.189-195
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• 1973

With the gradual expansion of copper demands, the utilization of enormous tonnages of waste copper mineral containig up to 0.5% copper becomes available. In order to investigate the possibilities on the application of bacterial leaching method to waste dumps or abandoned mines, the authors had carried out microbial leaching of copper minerals by F.ferrooxidans isolated from the Dalsung copper mine water. The results obtained were as follows : 1. The copper extraction rate from the Dalsung chalcopyrite has been a little accerelated by using flasks in place of percolators. 2. The percentage of copper extracted from the Dalsung chalcopyrite sample was 100% in 30 days in the presence of iron-oxidizing bacteria F.ferrooxidans while 9.27% in the absence of bacteria. 3. F.ferroxidans was capable of producing sufficient quantities of ferric sulfate and sulfuric acid from ferrous iron to bring about the dissolution of 100% of copper from the Dalsung chalcopyrite.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.52-54
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• 2009

A plane wave expansion method(PWEM) was applied for photonic band structure calculation. We examined zero group velocity modes in photonic crystals. The zero group velocity was obtained in second band along G-K direction. We expanded Brillouin zone, and investigated on zero group velocity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.331-334
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• 2004

In clinical use, coronary stents keep coronary arteries open after expansion with a balloon catheter and prevent the expanded artery from collapsing. Coronary stents are positioned in artery by catheter with a balloon along a guide wire to the lesion site. Flexibility is one of important ability for delivery. In this paper, Palmaz-Schatz stent and Tenax complete stent were selected because these are the most representative of tubular stents. Finite element analyses for the stent system were performed using ABAQUS/Standard code. The present study estimated the flexibility of coronary stents due to loading directions. Moreover the present paper suggests a numerical method to test the flexibility of stents. In conclusion this paper shows how the finite element analysis can be effectively organized in the stent development.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.104-107
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• 2003

The ageing cause in many porcelain suspension insulators which occur on transmission and distribution line with dead-end stings is mechanical stress in interface between porcelain and cement materials. It is known that the principal mechanical stress which give electrical failure is the results of the displacement is due to cement growth. We studied an analysing method to find out a deformation of brittle porcelain with a thermal expansion of cement for suspension insulator. These simulation analysis and experimental results show that cement volume growths affect severely to be mechanical failure ageing. These simulation analysis and experimental results show that axial loading affects of Porcelain insulators severely to be mechanical failure ageing.