• Transactions of Materials Processing
• /
• v.24 no.6
• /
• pp.387-394
• /
• 2015

Air springs are designed to support loads using the volume elasticity in a cylindrical shaped air bag made of a composite material with a rubber matrix and two plies of reinforced fibers. Recently, applications of these springs have been expanded from railway vehicles to passenger cars. The current study presents a finite element analysis of a manufactured air spring for a passenger car. The analysis was conducted including the mounting steps of the air bag using a static loading condition. A method for controlling the internal pressure and displacements during the mounting step was developed. The characteristic load curve and the shape of the air bag were in good agreement with the experimental data with respect to the design height, the bump height and the rebound height. Results indicate that ply angles of fibers vary from 38 degrees to 56 degrees during static loading.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.15 no.5
• /
• pp.188-192
• /
• 2005

High $T_c(Y_{0.5}Nd_{0.25}Sm_{0.25})Ba_2Cu_3O_y[(YNS)-123]$ superconductors with/without $CeO_2$ additive were systematically investigated by the zone melt growth process in air. Cylindrical green rods of (YNS)-123 oxides were fabricated by cold isostatic pressing (CIP) method using rubber mould. A sample prepared by this method showed well-textured microstructure, and $(Y_{0.5}Nd_{0.25}Sm_{0.25})_2BaCuO_5[(YNS)211]$ nonsuperconducting inclusions were uniformly dispersed in large $(Y_{0.5}Nd_{0.25}Sm_{0.25})Ba_2Cu_3O_y$[(YNS)123] superconducting matrix. In this study, optimum melting temperature and growth rate were $1100^{\circ}C$ and 3 mm/hr, respectively. The directionally melt-textured (YNS)-123 sample with $CeO_2$ additive showed an onset critical temperature $(T_c)\;T_c{\geq}93K$ and sharp superconducting transition.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.14 no.2
• /
• pp.68-72
• /
• 2004

Sm-doped YBCO high $T_c$ superconductor was directionally grown by zone melt growth process in air atmosphere. Cylindrical green rods of $(Sm/Y)_{1.8}Ba_{2.4}Cu_{3.4}O_{7-x}$[(Sm/Y)1.8] oxides were fabricated by cold isostatic pressing (CIP) method using rubber mold. Based on the variation of melting temperature and growth rate, the microstructure and superconducting properties were systematically measured by using optical micrographs, TEM and SQUID magnetometer. In this study optimum melting temperature and growth rate were $1085^{\circ}C$ and 3.5 mm/hr respectively. Nonsuperconducting $(Sm/Y)_2BaCuO_5$ inclusions of (Sm/Y)1.8 superconductor were uniformly distributed within the superconducting (Sm/Y) $Ba_2Cu_3O^{7-x}$ matrix. The directionally melt-textured (Sm/Y)1.8 superconductor showed an onset $T_c$ $\geq$ 90K and sharp superconducting transition.

• Restorative Dentistry and Endodontics
• /
• v.19 no.2
• /
• pp.513-533
• /
• 1994

The smooth surface after polishing of composite resin contributes to the patient's comfort, and appearance and longevity of the restoration. This study was performed for the quantitative analysis of the effects of the various finishing and polishing instruments on the surface roughness and reflectivity of the microfill, and hybrid composite resins. Cylindrical specimens 2mm thick and 10mm in diameter of Silux Plus, Durafill VS ; Z100, Prisma TPH, Brilliant, and Herculite XR composite resin were polymerized under the matrix strip. 18 specimens for each composite resin materials were divided into 6 groups ; 5 experimental groups were abraded with # 600 sand paper to remove resin-rich layer, except control. Thereafter, using diamond bur(Mani Dia-Burs), carbide bur(E. T. carbide set 4159), rubber point(Composite polishing kit), aluminum-oxide disk(Sof-Lex disk), polishing paste(Enhance system) ; each specimen was polished to its best achievable surface according to manufacturer's directions. Final polished surfaces were evaluated for the surface roughness with profilometer(${\alpha}$-step 200, Tencor instruments, USA) and for the reflectivity with image analyser(Omniment Image Analyser, Buehler, USA). The results were as follows. 1. Polishing paste or aluminum-oxide disk finish in the microfill, and hybrid composite resins was as smooth as matrix strip finish on the surface roughness test. 2. Polishing paste or aluminum-oxide disk finish in the microfill ; polishing paste finish in the hybrid composite resins was as reflective as matrix strip finish on the refectivity test. 3. For the polishing paste, there were no significant differences between the composite resin materials on the surface roughness and refectivity tests. 4. For the aluminum-oxide disk, the best result was obtained with the microfill composite resin on the surface roughness and reflectivity test. 5. Diamond bur, carbide bur, and rubber point were inappropriate for the final polishing instruments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.227-231
• /
• 2014

Underwater radiated noise is one of the vital factors in underwater weapon systems like submarine. A passive elastic mount is an effective reduction method for the vibration from a ship-board machinery transmitted to the hull which is radiated as noise outside the hull. A passive elastic mount shows the limitation on the vibration reduction and needs multi stage mounting system including double stage one to meet the required underwater radiated noise criteria. It is necessary for the multi stage mounting system to consider the large displacement in the underwater shock explosion. So it is difficult to apply the multi stage mounting system in submarine because of space limitation. Also recent navy sonar system are trying to have the capability to detect the ship-borne acoustic signals in the low frequency range. An alternative to the passive mount is an active mount with moving-coil type electromagnetic actuator based on a conventional rubber mount in the low frequency range. In the previous paper, 4 active mounts with moving-coil type electromagnetic actuator based on the rubber mount were installed on the hard floor of the facility, which means no consideration on the elastic foundation effect for the control of the active mounts was taken into account. In this study, an experimental performance analysis on the active mount was carried out using 4 active mounts installed on the cylindrical structure to investigate the elastic foundation effect.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.3
• /
• pp.269-274
• /
• 2002

(Sm/Y)-Ba-Cu-O system high Tc composite superconductors with/without $CeO_2$ additive were directionally grown by zone-melting process, haying large temperature gradient, In air atmosphere. Cylindrical green rods of $({Sm/y})_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(Sm/Y)1.8] composite oxides by cold isostatic pressing(CIP) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The size of nonsuperconducting $({Sm/y})_2BaCuO_5$ inclusions of the melt-textured (Sm/Y)1.8 sample with CeO$_2$ additive were remarkably reduced and uniformly distributed within the superconducting (Sm/Y)1.8 matrix. Both samples, with/without $CeO_2$ additive, showed an onset Tc $\geq$ 90 K and sharp superconducting transition. The critical current density Jc value of the $CeO_2$ addictive were $1{\times}10^5A/\textrm{cm}^2$ in 77 K, 0 Tesla.

• Journal of the Society of Naval Architects of Korea
• /
• v.45 no.1
• /
• pp.73-80
• /
• 2008

An improved method to measure the dynamic viscoelastic properties of elastomers is proposed. The method is based on the analysis of forced oscillation of a cylindrical sample loaded with inertial mass. No special equipment or instrumentation other than the ordinary vibration measurement apparatus is required. Typical measurement of the viscoelastic properties of a silicone rubber $Silastic^{(R)}$ S2 were measured over the wide frequency range from 10 Hz to 3 kHz under the action of wide region of deformation from $10^{-4}%$ to 5%. It was shown that modulus of elasticity and loss tangent fall on the single curves when the ratio of load mass to sample mass changed from 1 to 20.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.2
• /
• pp.110-113
• /
• 2016

(YNdSm)-Ba-Cu-O system high Tc composite superconductors were directionally grown by zone melting process, having large temperature gradient, in air atmosphere. Cylindrical green rods of $(YNdSm)_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(YNS)1.8]composite oxides by CIP (cold isostatic pressing) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, TEM and SQUID magnetometer. The size of nonsuperconducting $(YNdSm)_2BaCuO_5$ inclusions of the melt-textured (YNS)1.8 sample with $CeO_2$ additive were remarkably reduced and uniformly distributed within the superconducting (YNS)1.8 matrix. (YNS)1.8 samples, with / without $CeO_2$ additive, showed an onset $T_c{\geq}90K$ and sharp superconducting transition. The critical current density $J_c$ value of the (YNdSm)1.8 superconductor with $CeO_2$ additive were 840 A, $1.2{\times}104A/cm^2$ in 77 K, 0 Tesla by direct current transport method.

• Geomechanics and Engineering
• /
• v.2 no.3
• /
• pp.177-190
• /
• 2010

This paper presents the details of indigenous development of the piezovibrocone and calibration chamber. The developed cone has a cylindrical friction sleeve of $150cm^2$ surface area, capped with a $60^{\circ}$ apex angle conical tip of $15cm^2$ cross sectional area. It has a hydraulic shaker, coupled to the cone penetrometer with a linear displacement unit. The hydraulic shaker can produce cyclic load in different types of wave forms (sine, Hover sine, triangular, rectangular and external wave) at a range of frequency 1-10 Hz with maximum amplitude of 10 cm. The piezovibrocone can be driven at the standard rate of 2 cm/sec using a loading unit of 10 ton capacity. The calibration chamber is of size $2m{\times}2m{\times}2m$. The sides of the chamber and the top as well as the bottom portions are rigid. It has a provision to apply confining pressure (to a maximum value of $4kg/cm^2$) through the flexible rubber membrane inlined with the side walls of the calibration chamber. The preliminary static as well as dynamic cone penetration tests have been done sand in the calibration chamber. From the experimental results, an attempt has been made to classify the soil based on friction ratio ($f_R$) and the cone tip resistance ($q_c$).

• Elastomers and Composites
• /
• v.34 no.1
• /
• pp.45-52
• /
• 1999

This paper describes how the gold particles self assemble on the specific phase on the microphase separated block copolymer thin film and form a well ordered patterns. For this study, polystyrene-polybutadiene-polystyrene (PS-PB-PS) triblock copolymer (30wt % PS) thin films (${\sim}100nm$) having a cylindrical morphology were cast from 0.1wt% toluene solution to be used as polymer thin film templates. The films having either vertical PS cylinders or in-plane PS cylinders in PB matrix from each different solvent evaporation condition were obtained. Cross-sectional transmission electron microscopy(TEM) was used to study the surface and bulk morphologies of block copolymer thin films. Small amount of gold particles was evaporated on a block copolymer thin film template to obtain a nano-scale pattern. When an as-cast thin film template was used, gold particles preferentially self assemble on the low surface tension PB phase and a relatively well ordered pattern in nano-scale was produced. However, after the formation of a low surface energy PB rich layer upon annealing, a gold self-assembled pattern was not observed.