• Journal of Environmental Science International
• /
• v.11 no.3
• /
• pp.155-160
• /
• 2002

Using measured data at Daegu by tethersonde for the period of 1984∼1987, we have investigated the lower atmospheric boundary layer structure including relationships between inversion layer and meteorological factors(wind and temperature), and the inversion strength and inversion height. The inversion layer was defined from the vertical temperature profile and its strength was analyzed with the wind shear as well as the vertical temperature gradient. From October to January, measured inversion layer isn't destroyed, however, in June, after sun rise, it is destroyed by surface heating and mixed layer is developed from surface. According to Pasquill stability classes, the moderately stable cases dominated. It's the larger vertical temperature gradient the lower SBL height. We have introduced B(bulk turbulence scale) which indicated SBL height. It's larger B, the higher SBL height and vice versa. It was noted that the bulk turbulence scale (B) is appropriate to determine the stable boundary layer height.

• Steel and Composite Structures
• /
• v.7 no.4
• /
• pp.263-278
• /
• 2007

A finite element implementation of the modified compression field theory (MCFT) using a tangential formulation is presented in this work. Previous work reported on implementations of MCFT has concentrated mainly on secant formulations. This work describes details of the implementation of a modular algorithmic structure of a reinforced concrete constitutive model in nonlinear finite element schemes that use a Jacobian matrix in the solution of the nonlinear system of algebraic equations. The implementation was verified and validated using experimental and analytical data reported in the literature. The developed algorithm, which converges accurately and quickly, can be easily implemented in any finite element code.

• Proceeding of EDISON Challenge
• /
• 2016.03a
• /
• pp.228-233
• /
• 2016

Auxetic material is a material which has negative Poisson's ratio(NPR). Auxetic material shows some distinctive property like high energy absorbing property and high shear modulus. Among these, synclastic curvature is very interesting characteristic. When synclastic-curvature-material bends, it changes its shape like dome, contrary to non-auxetic material which changes its shape like saddle(anticlastic). This distinctive property could make it easy to manufacture curved structure like nose cone or wing panel in aerospace engineering. In this study, we studied a quantitative analysis about synclastic curvature of re-entrant panel with finite element model. We suggested a concept 'Degree of Synclasticity(DOS)', which means a ratio of curvature of load-direction and load-orthogonal direction. We studied the variation of DOS with two factor, unit cell inner angle(${\theta}$) and load position angle(${\phi}$). DOS decreases as ${\theta}$ increases because the unit cell goes out of auxetic-shape. As ${\phi}$ varies, DOS changes in a large range. So proper optimization of ${\phi}$ would be needed for application.

• Economic and Environmental Geology
• /
• v.24 no.3
• /
• pp.309-318
• /
• 1991

Analysis for landslides was studied in framework of Chungju dam right abutment, 6.5km northeast of Chungju city. $5.5{\times}10^6m^3$ landslide materials were excavated during dam construction for safety of the Chungju dam. Geology of study area is composed mainly of meta sediments such as dolomitic limestone, quartzite and schist which are dipping toward the Nam Han river. Scanline survey of discontinuities was performed for slope stability, resistivity exploration was performed for the evaluation of potential failure plane, and direct shear strength test of rocks and soils was performed for the effect on landslide. Monitoring systems of tiltmeter, tensiometer, ground water observation hole and level monument were installed during dam construction and interpreted for the evaluation of slope instability. Kinematic solution of the geological structure and evaluation using safety factor for slope may prove the failure of the slope.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1999.10a
• /
• pp.265-272
• /
• 1999

This stability of a plate structure is very crucial problem which results in wrinkle and bucking. In this study, the effect of the pattern of spot-welding points of the two rectangular plates on the compressive and shear bucking load is studied with respect to the thickness, aspect ratio of plates and number of welding spots. Buckling coefficient of the plate not welded was compared with that of two plates with various thickness to extract the effect of thickness. The effect of number of welding spots are studied in two directions, longitudinal and transverse directions. The conclusions obtained were that the reinforcement effect was maximized when the aspect ratio was close to 1.75 at compressive load condition and that the effect of number of welding spots in transverse direction was larger than that in longitudinal direction at shearing load condition.

• The Journal of Korean Physical Therapy
• /
• v.2 no.1
• /
• pp.103-112
• /
• 1990

The intervertebral disc in the anterior portion of the function unit gives the spine its flexibility. The disc is attached closely to the vertebral endplates. Between these endplates and the annulus fibrosus, the nucleus pulposus of the lumbar disc is enclosed in a circle of unyielding tissues. Compressive pressure placed on the disc is dissipated circumferentially in a passive manner In response to the greater axial forced exerted on the lumbar spine in comparison to the cervical and thoracic spines, the nucleus pulposus has its greatest surface area in the lumbar spine. The intervertebral disc is not only structure that helps diss pate stresses placed on the spine. With flexion, extension, rotation, or shear stress, the load distribution on the function unit is shared by the intervertebral disc, anterior and posterior longitudinal ligaments, the facet joints and capsules, and other ligamentous structures like the ligamentum flavum, interspinous and supraspinous ligaments, which attach to the posterior elements of the functional unit.

• KSTLE International Journal
• /
• v.8 no.2
• /
• pp.35-37
• /
• 2007

The electrorheological behavior of the glucosamine and glucosamine hydrochloride suspensions was investigated. The the glucosamine suspension behaved as a Newtonian fluid due to low conductivity even though it has polar group. The glucosamine hydrochloride suspension behaved as a Nonnewtonian fluid under the application of the electric field. The shear stress of the glucosamine hydrochloride suspension is proportional to 1.86 power of the electric field. The value of the structure factor, $A_s$ was 1 and it may be resulted due to the formation of single chain upon application of the electric field.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.6_spc
• /
• pp.667-673
• /
• 2016

Canister with composite sandwich panel has been suggested owing to its higher stiffness and strength over a weight for square shaped canisters. The pyro shock induced by a short time explosion inside a canister is generally considered to be the most severe source of load affecting on the entire structure. Therefore, in this study, the approach and modeling method to identify the effect of pyro shock on canister with composite sandwich panel in a numerical way were mainly discussed. Moreover, the verification was implemented through comparison with test results.

• 한국가시화정보학회:학술대회논문집
• /
• 2006.12a
• /
• pp.55-58
• /
• 2006

The flow characteristics in a confined slot jet impinging on a flat plate were investigated by using cinematic Particle Image Velocimetry technique. The three different kinds of confined slot were applied to the jet with a view to evaluating the shape effect and the jet Reynolds number was varied from 250 to 1000 for a fixed jet-to-plate spacing of H/W=5. It was found that the vortex structures in the shear layer are developed with increase of Reynolds number and that the jet becomes unsteady by the interaction of vortex pairs between 500 and 750 of Reynolds number. Finally, the slot shape was proved to be related with the generation timing of vortex pair and the temporal vortex structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.815-820
• /
• 2000

The early damage detection of large structures is very important to prevent the disaster due to its global failure. In this paper, a damage detection method of the beam-analogy structure based on the wavelet transformation of mode shape is presented. This can effectively detect the singularity of mode shape caused to the inconsistency of bending moment and shear force at the damaged part using the discrete wavelet and its inverse transforms. To investigate the validity and the applicability of the presented damage detection method, numerical simulation and experiment are carried out for the idealized beam and the real ship structures.