• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.3
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• pp.127-131
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• 2010

A two-layer fluid with free surface is simulated in the time domain by a two-dimensional potential-based Numerical Wave Tank (NWT). The developed NWT is based on the boundary element method and a leap-frog time integration scheme. A whole domain scheme including interaction terms between two layers is applied to solve the boundary integral equation. The time histories of surface elevations on both fluid layers in the respective wave modes are verified with analytic results. The amplitude ratios of upper to lower elevation for various density ratios and water depths are also compared.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.94-101
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• 2017

Recently, the small quantity batch production method has come into the spotlight as there are more plastic processing methods. At the same time, the 3D printer market has become globally widespread due to expired 3D printer patents. In particular, the FDM method is widely used for cheap products and materials. However, the FDM scheme is not as good as the injection molding method for quality and strength. This study investigated the effect of the internal filling and strength according to layer thickness to search for the optimum printing of the factors (infill and layer thickness) that determine the strength of the model.

• Journal of KSNVE
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• v.6 no.5
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• pp.671-677
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• 1996

This paper presents the analytical method for predicting turbulence- induced noise in the multilayered cylinder composed of an outer hose, an inner fluid and an internal core. It is assumed that an infinite axisymmetric cylinder is located horizontally in water with free stream velocity and the turbulent boundary layer (TBL) surrounding the outer hose is fully developed and homogeneous. The transfer function at the core surface due to the propagation of the pressure fluctuation within the TBL is formulated using the linearized Navier-Stockes equation for solid and fluid. In the estimation of the energy spectrum of wall pressure fluctuation, the empirical formula proposed by Strawderman based on the Corcos model is used. A general algorithm for the calculation of the pressure level at the surface of a core, that is, turbulence- induced noise, is presented. Through the detailed numerical simulation, it is found that the major noise mechanism is the propagation of the bulge wave along hose.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.3
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• pp.60-67
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• 1999

The CLSM and the image analysis technique enhanced observation of fiber wall fibrillation occurred in both the outer and the fiber wall surfaces during refining by non-destructive techniques. In the early stages of refining, it was well observed that a partial separation between the S1 and S2 layer in the secondary wall was made generating a space in the wet fiber walls . With further refining, it was clearly shown that the shear forces imparted by the refiner bar surfaces caused the S1 layer to become totally separated from the S2 layer as well as creating microfibrils. Furthermore, the fibrillation in the inner fiber wall surfaces could be due to the normal force (Fn) by refiner bars, friction force between a fiber and refiner bars (Fs) and inner friction force between fiber walls(fs). It was confirmed that the concept of fibrillation should be extended to fibrillation in the inner fiber wall surfaces as well as internal and external fribrillation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.104.2-104
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• 2001

In the intelligent integrated systems, the delay time must be reduced using highly parallel processors, as well as high throughput performance. In this paper, we propose a new concept for building 3D highly parallel processors using multi-layer printed wiring boards with built-in soldering heater (BISH-PWB). The proposed BISH is realized with the long and narrow cupper wiring pattern on the internal layer in the terminal pattern area. Based on the linearity of the cupper resistance vs. temperature, we can measure the BISH, temperature and its calorific value from the heater voltage and current measurements. If we provide the BISH temperature control systems for each BISH, selective multi-point soldering can be realized with same ...

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.297-305
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• 2010

Purpose: The purpose of this study was to observe the change of metal-mold reaction and surface roughness in titanium casting specimens for phosphate-silica alumina bonded investment with mold temperatures. Methods: The metal-phosphate silica alumina bonded mold interface reaction and surface roughness of titanium casting specimens according to mold temperatures were investigated. The Specimens were analysed by scanning electron microscopy and surface roughness tester. Results: The oxidation behavior indicated by the growth of oxide thickness. The titanium-oxide layer were consisted two layer of a porous external and a dense internal one. The reaction layer and surface roughness increased with increasing investment material temperature. Conclusion: In this work, The most suitable mold temperature in casting of pure titanium was $200^{\circ}C$.

• Interaction and multiscale mechanics
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• v.6 no.1
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• pp.1-14
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• 2013

The aim of this paper is to study the propagation of torsional surface waves in non-homogeneous isotropic layer of finite thickness placed over a homogeneous viscoelastic half-space, when both density and rigidity of the non-homogeneous medium are assumed to vary exponentially with depth. The frequency equations are obtained by using simple method of separation of variables. Further, it is seen that when viscoelastic parameter and non-homogeneity parameter is neglected, the dispersion equation gives the dispersion equations of Love waves in homogeneous, elastic and isotropic layer placed over homogeneous viscoelastic medium. The problem has been solved numerically and the effects of various inhomogeneities of the medium on torsional waves have been illustrated graphically.

• YAKHAK HOEJI
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• v.11 no.3_4
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• pp.33-35
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• 1967

The internal structures of "Chunho", "Kangwhal" and "Dangui" and their original plants had been compared with each other in the prior report. Coumarin derivatives, khellactone from the roots of Angelica purpuraefolia $C_{HUNG}$ and decursin and decursinol from A. gigas $N_{AKAI}$ were also isolated. In this report, we made a simple and convenient identification method for the powdered drugs of several Angelica genus by using a thin layer chromatogrophic technique. The ehter extract of the powdered drugs were applied to a silica gel plate, and was developed with n-hexane and ethyl acetate (1:1) mixture. The characteristic U.V. absorption patterns of each drug were shown.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.05a
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• pp.219-224
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• 2004

The present study was to investigate the heat transfer enhancement effect of coil wire fins in an ice storage system. For the two cases of tubes with internal brine flows, a finned tube with coil wires on its outer surface and a smooth tube, the rates of ice layer were tested and compared for both the icing processes. The coil fins were made of a stainless steel wire with a dia. of 2.0(mm), and the coil had an outer dia. of 10(mm) and a helix angle of 60($^{\circ}$). The experimental results showed that the coil fins could substantially reduce the thermal resistance of the ice layer, and enhance the heat flow rates between the water in the storage tank and the brine. The ice storing time was found to be shortened by 13(%) for the coil fins to get the same amount of ice layer that was built on the smooth tube wall for 10 hours of operation when the same thermal conditions were provided.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1343-1350
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• 1998

A study is made of mechanical properties of unglazed matrix as a funtion of sintering temperature and crack patterns in layer structur pottery consisting of glaze and substrate and in matrix which is sintered at 120$0^{\circ}C$ and 130$0^{\circ}C$ respectively. The mechanical properties of matrix are increased due to density and vitrification to 130$0^{\circ}C$ The interface of glazed bilayer reveals the reactive intermediate layer. Herzian indentation testing is used to investigate the evolution of damage modes as a function of load. In the materials sintered at 120$0^{\circ}C$ quasi-plastic deformation is developed at the matrix and the cone-like cracks initiate at the glazing top surface and additionally upward-extending transverse cracks initiate at the internal in-just initiate at the glazing top surface which pass through the interface with increasing of indentation load. Finally the dominant damage mode shifts from substrate quasi-plasticity to coating fracture with increasing sintering temperature.