• Advances in nano research
• /
• v.8 no.3
• /
• pp.229-244
• /
• 2020

In this paper, modified Kelvin's model has been used to analyze the orthotropic vibration frequencies of single walled carbon nanotubes with clamped-clamped and clamped-free boundary conditions. For this system the governing equation is developed with wave propagation approach. Armchair, zigzag and chiral structures are considered for the vibrational analysis to investigate the effect of different modes, in-plane rigidity and mass density per unit lateral area. Throughout the computations, on decreasing the length-to-diameter ratios, the frequencies of said structure increases. In addition, by increasing three different value of in-plane rigidity resulting frequencies also increase and frequencies decrease on increasing mass density per unit lateral area. The results generated using computer software MATLAB to furnish the evidence regarding applicability of present model and also verified by available published literature.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2002.02a
• /
• pp.138-140
• /
• 2002

We fabricated textured Ni substrate for YBCO coated film and evaluated the degree of texture in terms of rolling condition and annealing time. The substrate was compacted from pure Ni powder and reduced the thickness to 100 $\mu$m by rolling followed by heat treatment. As decreasing the thickness of substrate, it was observed that the non-uniform deformation such as ‘wave edge’ or ‘wave buckle’ developed locally on it, causing reduced texture. On the other hand, uniformly deformed substrate showed better cube texture indicating the FWHM of in-plane and out-of-plane of about $11^{\circ}$ ~ $14^{\circ}$. In addition, annealing at $1000^{\circ}C$ for 1~ 8 hr did not make a remarkable difference on the texture.

• Proceedings of the Optical Society of Korea Conference
• /
• 1990.02a
• /
• pp.64-68
• /
• 1990

Boundary element method using linear basis function is applied to obtain fields scattered from a 3-D dielectric sphere. Electric field integral equation is used on the surfaces of the dielectric material where its surface is discretized into trilateral cells. For plane wave incidence, scattered fields by a dielectric sphere is calculated and compared with its analytic solution. The total electric fields are calculated on the great circle of the sphere boundary as well as the outside of the sphere in the plane of the wave vector and the polarization vector of the incident electric field.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.1
• /
• pp.36-42
• /
• 1998

In this study, active muffler was designed and was manufactured for exhaust noise reduction of commercial vehicle, then experiment of real vehicle was conducted. In a manufactured active muffler, because the flow of exhaust noise in tail pope outlet are become a plane wave, the global reduction if radiation noise from outlet and the placement of error microphone to avoid the exhaust gas of high temperature could be implemented. In control algorithm, reduction of noise of engine driving frequency and harmonic frequency can be archieved using proposed reference signal including a fixed speed state(2,000rpm, 3,000rpm, 4,000rpm) and a run-up speed state(2,000rpm$\rightarrow$4,000rpm) is accomplished with the active muffler installed in vehicle.

• Korean Journal of Optics and Photonics
• /
• v.13 no.2
• /
• pp.162-165
• /
• 2002

We propose an optical configuration for a transflective display mode using a transflective film and a half-wave AFLC cell whose in-plane tilt angle is 22.5。. It provides high brightness and high contrast in the reflective mode as well as in the transmissive mode.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.1
• /
• pp.22-28
• /
• 1999

An exact asymptotic solution for a perfect conducting wedge with H-polarized plane wave incidence is analytically derived by substituting the exact boundary fields of the perfeet conducting wedge, the well known series solution, into the dual integral exquation in the spectral domain. The validity of the derivation is assured by showing that the analytic integration gives the null fields in the complementary region. The merits taking the dual integral equation for derivation of an asymptotic solution for a perfect conduction wedge is discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.355-358
• /
• 2008

This study deals with a substantial problems with SEA modeling methods in shipboard noise predictions. As a first problems with respect to modeling, fineness of model that represents a real structure is numerically investigated by comparison among 3 models, Fine, Coarse and Simplified models. Comparison reveals that Fine model shows the lowest noise level among them since this model involve more energy transfer paths than the other models. Influence of in-plane wave is also examined by numerical comparison. It is clear that inclusion of in-plane wave affects the high frequency and the cabin far from a source.

• Journal of the Optical Society of Korea
• /
• v.13 no.2
• /
• pp.286-293
• /
• 2009

In this paper, we present an optimal shape design method for a dielectric microlens which is used to focus an incoming infrared plane wave in wideband, by exploiting the finite difference time domain (FDTD) technique and the topology optimization technique. Topology optimization is a scheme to search an optimal shape by adjusting the material properties, which are design variables, within the design space. And by introducing the adjoint variable method, we can effectively calculate a derivative of the objective function with respect to the design variable. To verify the proposed method, a shape design problem of a dielectric microlens is tested when illuminated by a transverse electric (TE)-polarized infrared plane wave. In this problem, the design variable is the dielectric constant within the design space of a dielectric microlens. The design objective is to maximally focus the incoming magnetic field at a specific point in wideband.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.4
• /
• pp.648-656
• /
• 2004

In this study, a highly efficient shell-and-tube heat exchanger with plate fins is considered to improve thermal performance of the conventional shell-and-tube heat exchanger. This type of shell-and-tube heat exchanger with plate fins of various shape is simulated three-dimensionally using a commercial thermal-fluid analysis code. CFX4.4. The effect of the shape of the plate fin on heat transfer characteristics is also investigated by the simulation. Plate fins of four different shapes. plane, plane-slit. wave. and wave-slit fins, are considered. The flow fields, pressure drop and heat transfer characteristics in the heat exchanger are calculated. It is proved that the shell-and-tube heat exchanger with plate fins is superior to the conventional shell-and-tube heat exchanger without plate fins in terms of heat transfer. The shape of the plate fin is important in the performance of a heat exchanger such as heat transfer and pressure drop.

• Proceedings of the KIEE Conference
• /
• 1999.11d
• /
• pp.1128-1130
• /
• 1999

Optical encoding method of images using random-phase encoding in both input and Fourier Planes was proposed by Javidi and his group, and the method was realized experimentally by Singh and his group with use of a photorefractive crystal and a phase conjugate wave.[1-2] Recently various techniques have been proposed theorically and experimentally. These include the method using one random-phase mask in the Fourier plane or two random-phase masks in the input and the Fresnel planes.[3] We demonstrate the difference and the problem of the methods using one or two random-phase masks in the Fourier or Fresnel plane. We perform the encoding and decoding in $LiNbO_3$ crystal using degenerate four-wave mixing.