• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.102-107
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• 2013

It is important to understand the vibrating behavior of plate structures for many engineering applications. In this study, vibration characteristics of strip plates which have finite width and infinite length are investigated theoretically and numerically. The waveguide finite element approach is used in this study which is known as an effect tool for waveguide structures. WFE method requires only cross-sectional FE model and uses theoretical harmonic solutions for the wave propagation along the longitudinal direction. First of all for a simple strip plate, WFE results are compared with theoretical ones such as the dispersion diagrams, point mobilities, etc. to validate the numerical model. Then in the numerical analysis, the several different types of longitudinal stiffeners are included to the plate model to investigate the effects of the stiffeners in terms of the dispersion curves and mobilities.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.160-168
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• 1999

This paper describes one method of reverse engineering that machines a free form shape without descriptive model. A portable five-axes 3D CMM was used to digitize point data from physical model. After approximation by rational B-spline curve from digitized point data of a geometric shape, a surface was constructed by the skinning method of the cross-sectional design technique. Since a surface patch was segmented by fifteen part, surface merging was also implemented to assure the surface boundary continuity. Finally, composite surface was transferred to commercial CAD/CAM system through IFES translation in order to machine the modeled geometric shape.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.205-212
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• 2003

Many people are exposed to accidents by vehicles or sports. The most frequent injuries by these accidents is concerned with a knee joint. The three-dimensional surface model of a knee is needed for dynamic analysis of knee motion and knee reconstruction. three-dimensional motion data of a knee joint were obtained using X-ray and precise magnetic sensors. The surface data of a femur and a tibia were obtained using cross-sectional pictures by CT. The three-dimensional surface models of a femur and a tibia were made by the method of optimal triangular patch. Using obtained motion data, we simulated the motion of three-dimensional knee joint model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.8
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• pp.628-636
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• 1998

LB layers L-$\alpha$-DLPC deposited by LB method were deposited onto n-type silicon wafer as Z-type film. Films made up of 8, 16 layers of lipid with long alkyl chain and the thickness of monolayer and multiayers was determined by ellipsometry. Ut was deposited Ag and Al onto LB layers and silicon wafer for electrode and small electrode exhibit high capacitiance and low lekage current. The C-V curves of the MLS capacitor shows very high saturation value of capacitance. And cross-sectional SEM image of MLD capacitor indicated the presence of pore with Al electrode and we found that the Ag is good for electrode metal.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.243-246
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• 2000

This paper addresses a new technique of measuring the mean flow velocity not only over the cross sectional area but also along the pipe by exploiting the acoustic plane waves in the pipe. When fluid flows in the pipe and two plane waves propagate oppositely through the medium in it, the flow velocity causes a change of the wave number of the plane waves. The wave number of the positive going plane wave decreases but oppositely that of negative going one increases in comparison to no flow of the medium in the pipe. Theoretical backgrounds of this method are in details discussed and measurement results of the mean flow velocity are illustrated to reveal the feasibility and effectiveness of the suggested technique.

• Structural Engineering and Mechanics
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• v.48 no.3
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• pp.383-394
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• 2013

Cold-formed profiles have been largely used in the building industry because they can be easily produced and because they allow for a wide range of sections and thus can be utilized to meet different project requirements. Attainment of maximum performance by structural elements with low use of material is a challenge for engineering projects. This paper presents a numerical study aimed at minimizing the weight of lipped and unlipped cold-formed channel columns, following the AISI 2007 specification. Flexural, torsional and torsional-flexural buckling of columns was considered as constraints. The simulated annealing method was used for optimization. Several numerical simulations are presented and discussed to validate the proposal, in addition to an experimental example that qualifies its implementation. The ratios between lips, web width, and flange width are analyzed. Finally, it may be concluded that the optimization process yields excellent results in terms of cross-sectional area reduction.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.457-464
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• 2003

In the powder compact melting technique, proper precursor fabrication is very important because density distribution after foaming and foamability are determined during precursor fabrication process. The fabrication of the precursor has to be performed very carefully because any residual porosity or other defects will lead to poor results in further processing. In order to evaluate the effect of the compaction parameters on the kinetics of the foaming process, a series of experiments were performed. In this study, aluminium foams with a closed cell structure were fabricated by using both the powder compact method and the induction heating process. A proper induction coil was designed to obtain a uniform temperature distribution over the entire cross sectional area of precursor. To establish the foamable precursor fabrication conditions, effects of process parameters such as the titanium hydride content (0.3∼1.5 wt.%), pressing pressure of the foamable precursor (50∼150kN) on the pore morphology were investigated.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.154-162
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• 1986

This paper is studied in order to examine eight provinces as Agricultural zone in the early Chosun-Dynasty. The research method of this study depends on discriminant analysis. The research data is obtained from geography of Sejong sillok. In this approach, we believe the possibility of more scientific analysis of agricultural zone. So all cross-sectional data of this period were analysed by means of the discriminant analysis method. In the discriminant analysis of the eight provinces, 54.6% of the country were discriminated. In the territorial map, Kyongsang and Cholla were crossly adjoined and Chungcheong was located in the middle of them. While, Kyonggky and Hwanghae were adjoined in the center, and Pyongan and Hamgil were crossly adjoined, too. And Kangwon was located in the middle of them. Consequently their regional distribution varied widely and the agriculture of this period had considerable regional gaps.

• Structural Engineering and Mechanics
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• v.11 no.1
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• pp.17-34
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• 2001

An improved method has been developed for the computation of the section forces and stiffness in nonlinear finite element analysis of RC plane frames. The need for a new approach arises because the conventional technique may have a questionable level of efficiency if a large number of layers is specified and a questionable level of accuracy if a smaller number is used. The proposed technique is based on automatically dividing the section into zones of similar state of stress and tangent modulus and then numerically integrating within each zone to evaluate the sectional stiffness parameters and forces. In the new system, the size, number and location of the layers vary with the state of the strains in the cross section. The proposed method shows a significant improvement in time requirement and accuracy in comparison with the conventional layered approach. The computer program based on the new technique has been used successfully to predict the experimental load-deflection response of a RC frame and good agreement with test and other numerical results have been obtained.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.4
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• pp.64-72
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• 1995

Sizing design sensitivity analysis of structures subjected to the harmonic vibration is performed using adjoint variable method. Constraint is the stress and sizing design variables are thickness, bending moment of inertia, and cross-sectional area of structures. Accurate sensitivities are computed and plotted sensitivity can be used as a design guidance tool. The accuracy of sensitivities is verified by the finite difference values. Also, optimal design of three-bar structure is performed using the computed sensitivity and feasible direction method while satisfying constraints and obtaining the minimum weight.