• Journal of the Korean Home Economics Association
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• v.49 no.8
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• pp.63-71
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• 2011

The excavated costume of Jangheung Ma's included jeogoris, skirts, and pants, and a jungchimak(중치막), jangot(장옷), cheolrik(철릭), and jikryeong(직령). Most of the items were made of silk and cotton. The clothes for shrouding were plainer than those found in other regions. The method of sewing was mostly broad-stitching, but backstitch, hem tacking and decorative saddle stitching were also used. Unlined clothes were made with on old method of sewing(옛쌈솔), which was used mainly in the early period of the Chosun dynasty. Dating of the excavated costume can be determined by examining the collar of the Korean coat or jacket, the shape and form of sleeve, the size of the sub, and the form of gusset. Straight, diagonal, and broad sleeves were the most commonlyused shapes of sleeve in the middle period of $17^{th}$ century. In the latter period of Chosun, the trend moved towards a single-sub.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.281-295
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• 2005

The purpose of this paper is to study a class of delay differential equations with two delays. First, we consider the existence of periodic solutions for some delay differential equations. Second, we investigate the local stability of the zero solution of the equation by analyzing the corresponding characteristic equation of the linearized equation. The exponential stability of a perturbed delay differential system with a bounded lag is studied. Finally, by choosing one of the delays as a bifurcation parameter, we show that the equation exhibits Hopf and saddle-node bifurcations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1581-1593
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• 2001

An efficient variable-reordering method for finite element meshes is used and the effect of variable-reordering is investigated. For the element renumbering of unstructured meshes, Cuthill-McKee ordering is adopted. The newsy reordered global matrix has a much narrower bandwidth than the original one, making the ILU preconditioner perform bolter. The effect of variable reordering on the convergence behaviour of saddle point type matrix it studied, which results from P2/P1 element discretization of the Navier-Stokes equations. We also propose and test 'level(0) preconditioner'and 'level(2) ILU preconditioner', which are another versions of the existing 'level(1) ILU preconditioner', for the global matrix generated by P2/P1 finite element method of incompressible Navier-Stokes equations. We show that 'level(2) ILU preconditioner'performs much better than the others only with a little extra computations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.2
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• pp.31-36
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• 2003

Base and saddle feed drive system in machine tool puts in operation for Improvement of life and endure by high frequency heat treatment. In this time, work requirement of establishment to gets by repeat experimentation. In this paper, using the finite elementary method, we predict and revision processing, and gets minimizing of deformation and reduce the progress of Grinding works. Moreover, having high frequency heat treatment, the maximum deformation genesis m the middle parts without slideway length. Take deformation Into finite element program (ANSYS) of taper process in roughing process, after having high frequency heat treatment, existed quantity of deformation can be reduced down to 80 percents.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.440-445
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• 1999

One of the important technical issues is how to decrease thermal expansion of ballscrew in proportion to the increase of machining speed. When measuring force of stretch of ballscrew, since not only actual expansion and the value of bending have to be considered, it's impossible to definite the exact value of expansion. In addition, support bearings of ballscrew gain considerable force in axial direction. It also generates thermal expansion on the ballscrew, and deteriorates the bearings. In conclusion, it's impossible to give the pretension enough to absorb the all elongation due to thermal expansion generated during machine running. If gave, bed, column and saddle are all bent to change machine accuracy, and the pretension of support bearing of ballscrew in machine tool.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.51-56
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• 2002

In order to achieve high precision machine tools, Performance enhancement of feed drive systems is required. One of the important technical issues is how to decrease thermal expansion of ball screw in proportion to the increase of machining speed. When measuring force of stretch of ball screw, since not only actual expansion and the value of bending have to be considered, it is impossible to define the exact value of expansion. In addition, support bearings of ball screw gain considerable force in axial direction. It also generates thermal expansion on the ball screw, and deteriorates the performances of the hearings. In conclusion, it is impossible to give the pretension enough to absorb all the elongation due to thermal expansion generated during machine is running. If given bed column and saddle are all bent to chance machine accuracy, and the support bearings of ball screw is damaged.

• Journal of the Korean Mathematical Society
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• v.50 no.4
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• pp.695-713
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• 2013

We formulate and study a predator-prey model with non-monotonic functional response type and weak Allee effects on the prey, which extends the system studied by Ruan and Xiao in [Global analysis in a predator-prey system with nonmonotonic functional response, SIAM J. Appl. Math. 61 (2001), no. 4, 1445-1472] but containing an extra term describing weak Allee effects on the prey. We obtain the global dynamics of the model by combining the global qualitative and bifurcation analysis. Our bifurcation analysis of the model indicates that it exhibits numerous kinds of bifurcation phenomena, including the saddle-node bifurcation, the supercritical and the subcritical Hopf bifurcations, and the homoclinic bifurcation, as the values of parameters vary. In the generic case, the model has the bifurcation of cusp type of codimension 2 (i.e., Bogdanov-Takens bifurcation).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.4
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• pp.204-208
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• 2006

In this study, we investigated the ion energy distributions in a chlorine based inductively coupled plasma by quadrupole mass spectrometer with an electrostatic ion energy analyzer. Ion energy distributions are presented for various plasma parameters such as $BCl_3/Ar$ gas mixing ratio, RF power, and process pressure. As the $BCl_3/Ar$ gas mixing ratio and process pressure decreases, and RF power increases, the saddle-shaped structures is enhanced. The reason is that there are ionized energy difference between $BCl_3$ and Ar, change of plasma potential, alteration of mean free path. and variety of ion collision in the sheath.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.33-38
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• 2007

Since it is difficult to analytically express the Melnikov function when a dynamic system possesses multiple saddle fixed points with homoclinic and/or heteroclinic orbits, this paper investigates a vehicle model with nonlinear suspension spring and hysteretic damping element, which exhibits multiple heteroclinic orbits in the unperturbed system. First, an algorithm for Melnikov integrals is developed based on the Melnikov method. And then the amplitude threshold of road excitation at the onset of chaos is determined. By numerical simulation, the existence of chaos in the present system is verified via time history curves, phase portrait plots and $Poincar{\acute{e}}$ maps. Finally, in order to further identify the chaotic motion of the nonlinear system, the maximal Lyapunov exponent is also adopted. The results indicate that the numerical method of estimating chaotic threshold is an effective one to complicated vehicle systems.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.301-302
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• 1998

A quadrature RF coil has been developed for 0.3 Tesla permanent MRI systems. The quadrature RF coil is composed of a solenoid coil and a saddle shaped coil. To minimize the coupling ratio between the two coils, each coil is serially connected to a small extra loop. and the small loops are magnetically coupled to each other. By deliberately adjusting relative positions of the small loops, we have decreased the coupling ratio up to -30dB.