• Journal of Sensor Science and Technology
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• v.18 no.4
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• pp.294-300
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• 2009

Cardiopulmonary resuscitation(CPR) is performed by artificial ventilation and thoracic compression for the patient under emergent situation to maintain at least the minimum level of respiration and blood circulation for life survival. Quality of the pre-hospital CPR not only significantly affects the patient's survival rate but also minimizes side effects caused by CPR. Good quality CPR requires monitoring respiration, however, traditional respiratory air flow transducers cannot be used because the transducer elements are located on the flow axis. The present study developed a new technique with no physical object on the flow stream but enabling the air flow measurement and easily incorporated with the CPR devices. A turbulence chamber was formed in the middle of the respiratory tube by locally enlarging the cross-sectional area where the flow related turbulence was generated inducing energy loss which was in turn converted into pressure difference. The turbulence chamber was simply an empty enlarged air space, thus no physical object was placed on the flow stream, but still the flow rate could be evaluated. Both inspiratory and expiratory flows were obtained with symmetric measurement characteristics. Quadratic curve fitting provided excellent calibration formula with a correlation coefficient>0.999 (P<0.0001) and the mean relative error<1 %. The present results can be usefully applied to accurately monitor the air flow rate during CPR.

• Steel and Composite Structures
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• v.19 no.5
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• pp.1095-1113
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• 2015

In order to determine the mechanical behavior of the curved laminates in practical applications, three right-angled composite brackets with different lay-ups were investigated both experimentally and numerically. In the experimental, quasi-static tests on both unidirectional and multidirectional curved composite brackets were conducted to study the progressive failure and failure modes of the curved laminates. In the numerical modeling, three-dimensional finite element analysis was used to simulate the mechanical behavior of the laminates. Here, a strength-based failure criterion, namely the Ye criterion, was used to predict the delamination failure in the composite curved laminates. The mechanical responses of the laminate subjected to off-axis tensile loading were analyzed, which include the progressive failure, the failure locations, the load-displacement relationships, the load-strain relationships, and the stress distribution around the curved region of the angled bracket. Subsequently, the effects of stacking sequence and thickness on the load carrying capacity and the stiffness of the laminates were discussed in detail. Through the experimental observation and analysis, it was found that the failure mode of all the specimens is delamination, which is initiated abruptly and develops unstably on the symmetric plane, close to the inner surface, and about $29^{\circ}$ along the circumferential direction. It was also found that the stacking sequence and the thickness have significant influences on both the load carrying capacity and the stiffness of the laminates. However, the thickness effect is less than that on the curved aluminum plate.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.420-427
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• 1993

Dielectric thin film mirrors are embedded in multimode and single-mode fibers by a fusion splicing technique. The fibers with $45{\circ}$ angled embedded mirrors serve as ultra-compact directional couplers with low excess optical loss of 0.2 dB for multimode and 0.5 dB for single mode at 1.3 ${\mu}m$ and excellent mechanical properties. The reflectance is wavelength dependent and strongly polarization depencient. Far-field scans of the reflected output power measured with a white-light source show a pattern which is almost circularly symmetric with aspect ratio of 1.09 at 5% of the peak power. The splitting ratio in a multimode coupler measured with a diode laser source is much less dependent on input coupling conditions than in conventional fused biconical-taper couplers, indicating that these couplers are less susceptible to modal noise occuring in optical fiber communication systems. Spectral properties of multilayer internal mirrors normal to the fiber axis have been investigated experimentally, and a matrix analysis has been used to explain the results.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.175-180
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• 2000

The intensity of beam of light entering near the pupil edge is less than when it passes through the center of the pupil, this phenomenon is known as the Stiles-Crawford effect. In this paper, we investigate the variation in the shape of confusion circle when the real amplitude distribution of incident beam in pupil area is shifted to any direction by effects. The shape of confusion circle on the image surface is rotational symmetric when the real amplitude distribution of incident beam in pupil area isn't shifted, and the shape of confusion circle on the image surface is asymmetric as ellipse when the real amplitude distribution of incident beam in pupil area is shifted. The shifted direction of the real amplitude distribution of incident beam in pupil area equals the major axis direction of confusion circle on the image surface. When the shifted direction of the real amplitude distribution of incident beam in pupil area changes from ${\Delta}{\phi}$ to ${\Delta}{\phi}+{\pi}$, the intensity distributions and the shapes of confusion circle on the image surface for ${\Delta}{\phi}$ equals that for ${\Delta}{\phi}+{\pi}$. We know from above results that the influences of ${\Delta}{\phi}+{\pi}$ and ${\Delta}{\phi}+{\pi}$ cases on the image quality of optical system equal.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.3
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• pp.82-91
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• 1996

This is a basic study for the static and dynamic analysis on the elasto-plastic and elasto-viscoplastic of an axi-symmetric shell. The objective of this study was to investigate the mechanical characteristics of a nuclear reinforced concrete containment structure, which was selected as a model, by a numerical analysis using a finite element method. The structure was modeled with discrete ring elements of 8-noded isoparametric element rotating against the symmetrical axis, and the interaction between the foundation and the structure was modeled by Winkler's model. Also, the meridional tendon was modeled with 2-node truss elements, and the hoop tendon was done with point elements in two degrees of freedom. The effect of the tendon was considered without the increasement in total degree of freedom as the stiffness matrix of modeled tendon elements was assembled on the stiffness matrix of ring elements linked with the tendon. The results obtained from the analysis of an example were summarized as follows : 1. The stresses in the hoop direction on the interior and exterior surfaces of the structure were shown in changes of similar trend, and high stresses appeared on the structure wall 2. The stresses in the meridional direction on the interior and exterior surfaces were shown in change of different trend. Especially, the stresses at the junctions between the dome and the wall and between the wall and the bottom plate of the structure were very high, compared with those at other parts of the structure. 3. The stress changes in the direction of thickness on the crown of the dome were much linearly distributed. However, as the amount of tendon increased, the stresses in the upper and lower parts of the wall established with the tendon were shown stress concentration. 4. The stress changes in the direction of thickness on the center of the structure wall was linearly distributed in the all cases, and special stress due to the use of the tendon was not shown.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.6
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• pp.67-74
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• 2010

Because of the difference between the actual and computed eccentricity of buildings, symmetrical buildings will be affected by torsion. In provisions, accidental eccentricity is intended to cover the effect of several factors, such as unfavorable distributions of dead- and live-load masses and the rotational component of ground motion about a vertical axis. The torsional amplification factor is introduced to reduce the vulnerability of torsionally imbalanced buildings. The effect of the torsional amplification factor is observed for a symmetric rectangular building with various aspect ratios, where the seismic-force-resisting elements are positioned at a variable distance from the geometrical center in each direction. For verifying the torsional amplification factor in provisions, nonlinear reinforced concrete models with various eccentricities and aspect ratios are used in rock. The difference between the maximum displacements of the flexible edge obtained between using nonlinear static and time-history analysis is very small but the difference between the maximum torsional angles is large.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.4
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• pp.140-144
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• 2015

Effects of the shape, the size and the material of head mass on performances of tonpilz transducer were studied with a finite element method. The shape of head mass was changed with an angle between symmetric axis and side of head mass of transducer from 0 to 60 degree. As a result of the simulations, the bandwidth leached to 86.4 % at 35.5 degree in case of Al head mass. The size of head mass showed a decrease in the power of transducer with little change of bandwidth. For the Ti head mass, the transmitted power showed 100 % increase with a bandwidth of 88.1 % even though the weight of the head mass increased to 167 % of Al. This can be attributed to the mechanical properties like elastic modulus of Ti relative to Al.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.6
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• pp.348-352
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• 2016

In this paper, GaN film was grown on AlN/PSS by hydride vapor phase epitaxy compared with GaN on planar sapphire. Thin AlN layer for buffer layer was deposited on patterned sapphire substrate (PSS) by metal organic chemical vapor deposition. Surface roughness of GaN/AlN on PSS was remarkably decreased from 28.31 to 5.53 nm. Transmittance of GaN/AlN grown on PSS was lower than that of planar sapphire at entire range. XRD spectra of GaN/AlN grown on PSS corresponded the wurzite structure and c-axis oriented. The full width at half maximum (FWHM) values of ${\omega}$-scan X-ray rocking curve (XRC) for GaN/AlN grown on PSS were 196 and 208 arcsec for symmetric (0 0 2) and asymmetric (1 0 2), respectively. FWHM of GaN on AlN/PSS was improved more than 50% because of lateral overgrowth and AlN buffer effect.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.713-717
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• 1993

The crystal structure of the potassium salt of penicillin V has been studied by the X-ray crystallographic methods. Crystal data are as follows; potassium 3,3-dimethyl-7-oxo-6-phenoxyacetoamido-4-thia-1- azabicyclo[3.2.0]-heptane-2${\alpha}$-carboxylate, $K^+{\cdot}C_{16}H_{18}N_2O_5S^-$, $M_r$= 388.5, triclinic, Pl, a= 9.371 (1), b= 12.497 (2), c= 15.313 (2) ${\AA},\;{\alpha}= 93.74\;(2),\;{\beta}=99.32\;(1),\;{\gamma}=90.17\;(1)^{\circ},\;V=1765.7\;(2)\;{\AA}^3$, Z=4, $D_m=1.461\;gcm^{-1},\;{\lambda}(Cu\;K{\alpha})=1.5418\;{\AA},\;{\mu}=40.1\;cm^{-1}$, F(000)=808, T=296 K. The structure was solved by the heavy atom and difference Fourier methods with intensity data measured on an automated four-circle diffractometer. The structure was refined by the full-matrix least-squares method to a final R= 0.081 for 3563 observed $[I_0{\geq}2{\sigam}(I_0)]$ reflections. The four independent molecules assume different overall conformations with systematically different orientations of the phenyl groups although the penam moieties have the same closed conformations. There are intramolecular hydrogen bonds between the exocyclic amide nitrogen and phenoxy oxygen atoms. The penam moiety is conformationally very restricted although the carboxyl and exocyclic amide groups apparently have certain rotational degrees of freedom but the phenyl group is flexible about the ether bond despite the presence of the intramolecular N-H${\cdots}$O hydrogen bond. There are complicated pseudo symmetric relationships in the crystal lattice. The penam moieties are related by pseudo 20.5 screw axes and the phenyl groups by pseudo centers of symmetry. The potassium ions, related by both pseudo symmetries, form an infinite zigzag planar chain parallel to the b axis. Each potassium ion is coordinated to seven oxygen atoms in a severely distorted pentagonal bipyramid configuration, forming the infinite hydrophilic channels which in turn form the molecular stacks. Between these stacks, there are only lipophilic interactions involving the phenyl groups.

• Journal of the Korean Geotechnical Society
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• v.35 no.2
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• pp.37-51
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• 2019

This study focuses on the numerical simulations of the cone penetration tests in a sand ground. The mechanical responses of sand were described using the modified Mohr Coulomb plasticity model based on the critical state soil mechanics. In the plasticity model, the dilatancy angle was not a constant, but a function of the distance to the critical state line from the current state of void ratio and mean effective stress. To simulate cone penetration tests numerically, this study relied on Lagrangian finite element method under the axisymmetric condition. To enable penetration of the cone penetrometer without tearing elements along the symmetric axis, the penetration guide concept was adopted in this study. The results of numerical simulations on the calibration chamber cone penetration tests had good agreement with the experimental results.