• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.160-165
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• 2006

We have designed a high-transmission nano aperture in a perfect electric conductor film with the incident beam of 532 nm wavelength. The aperture basically has a C-shape and is known to produce a bright spot nearby the aperture in small size less than diffraction limit. The bright spot is strongly coupled with the local plasmon excited through the aperture hole. The characteristics of transmission and peak power of the aperture output were calculated using finite differential time domain (FDTD) technique, and the geometry of the aperture was determined to get a maximum transmission and peak power. To find the effect of the surface plasmon induced near by the aperture, we calculated the variations of the transmittance and the beam sizes by changing the size of the input beam irradiated on the aperture.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.1
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• pp.43-47
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• 2001

Plasma polymerized hexamethyldisiloxane thin film was fabricated by employing an inter-electrode capacitively coupled type apparatus under the following conditions : carrier gas flow rate of 11 sccm, reaction pressure of 0.1 torr, discharge frequency of 13.56 MHz and discharge power of 30∼90 W. Polymerization rate of thin film fabricated at the discharge power of 90W is 32.5nm/min. Relative dielectric constant and dielectric loss tangent of thin film shows 3.2∼3.8 and 2.6x10$\^$-3/∼4.51x10$\^$-3/ respectively in the frequency range of 1 kHz∼1 MHz. As the annealing temperature is increased, the relative dielectric constant gradually decreases while the dielectric loss tangent increases. The current density increase gradually with increasing annealing temperature and electric field. The electric conduction of the heaxamethyldisiloxane thin film shows Schottky effect.

• Environmental Engineering Research
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• v.11 no.3
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• pp.164-171
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• 2006

Numerical modeling of the flow velocity fields for the near corona wire electrohydrodynamic (EHD) flow was conducted. The steady, two-dimensional momentum equations have been computed for a wire-plate type electrostatic precipitator (ESP). The equations were solved in the conservative finite-difference form on a fine uniform rectilinear grid of sufficient resolution to accurately capture the momentum boundary layers. The numerical procedure for the differential equations was used by SIMPLEST algorithm. The Phoenics (Version 3.5.1) CFD code, coupled with Poisson's electric field, ion transport equations and the momentum equation with electric body force were used for the numerical simulation and the Chen-Kim ${\kappa}-{\varepsilon}$ turbulent model numerical results that an EHD secondary flow was clearly visible in the downstream regions of the corona wire despite the low Reynolds number for the electrode ($Re_{cw}=12.4$). Secondary flow vortices caused by the EHD increases with increasing discharge current or EHD number, hence pressure drop of ESP increases.

• Advances in nano research
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• v.9 no.3
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• pp.133-145
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• 2020

In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.105-116
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• 1996

The design and analysis of the transversely fed EMC(electromagnetically coupled) microstrip dipole have been accomplished by using the integral equation and MOM(method of moment)in frequency domain in order to find the current distribution of the dipole. In this study, we proposed the possibilities for design and analysis of EMC micro-strip dipole array antenna by means of calculating the current distribution of each dipole directly using the FDTD(finite difference time domain) method. In this case, we applied the formulation which is the finite difference expression of the Maxwell's integral equation. From the current distribution of each dipole, we calculated the far field electric component and showed that the calculation process and running time was reduced with respect to the method which calculates the radiation field with surface electric and magnetic current density.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.118.2-118.2
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• 2012

In particle-in-cell (PIC) simulation studies related to ion-ion two-stream instability, a reduced ion-to-electron mass ratio is often employed to save computation time. But it was not clearly verified how electrons dynamics are coupled with the slower evolution of ion-ion interactions under the external electric field. We have studied the ion beam driven instability using a 1D electrostatic PIC code by comparing different rescaling of parameter with real ion mass from the reference simulation with reduced ion mass. As the external electric field is stronger, the excited unstable mode range was more sensitively affected by the system size with the real mass ratio than the reduced ion mass. The results show that the reduced mass ratio should be used cautiously in PIC code as the electron dynamics can modify the ion instabilities. Additionally we found the formation of electron flat-top distribution in the final saturation stage. Simulation results show that in the early phase electrostatic solitary waves are quasi-periodically formed, but later they are fully dissipated resulting in heated, flat-top distributions. New electron beam components are occasionally formed. These are a consequence of the interaction with solitary wave structures. We parametrically investigate the development of electron phase space distributions for various drift speeds of ion beams and temperature ratios between ions and electrons

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1408-1409
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• 2007

In this paper, we developed a hybrid simulation model of carbon laser ablation under the Ar plasmas consisted of fluid and particle methods. Three kinds of carbon particles, which are carbon atom, ion and electron emitted by laser ablation, are considered in the computation. In the present modeling, we adopt capacitively coupled plasma with ring electrode inserted in the space between the substrate and the target, graphite. This system may take an advantage of ${\mu}m$-sized droplets from the sheath electric field near the substrate. As a result, in Ar plasmas, carbon ion motions were suppressed by a strong electric field and were captured in Ar plasmas. Therefore, a low number density of carbon ions were deposited upon substrate. In addition, the plume motions in Ar gas atmosphere was also discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.44-49
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• 2018

This study analyzed the Vulnerability of Network Communication devices when IEMI is coupled with the Network System. An Ultra Wide Band Generator (180 kV, 700 MHz) was used as the IEMI source. The EUTs are the Switch Hub and Workstation, which are used to configure the network system. The network system was monitored through the LAN system configuration, to confirm a malfunction of the network device. The results of the experiment indicate that a malfunction of the network occurs as the electric field increases. The data loss rate increases proportionally with increasing radiating time. In the case of the Switch Hub, the threshold electric field value was 10 kV/m for all conditions used in this experiment. The threshold point causing malfunction was influenced only by the electric field value. The correlation between the threshold point and pulse repetition rate was not found. However, in case of the Workstation, it was found that as the pulse repetition rate increases, the equipment responds weakly and the threshold value decreases. To verify the electrical coupling of the EUT by IEMI, current sensors were used to measure the PCB line inside the EUT and network line coupling current. As a result of the measurement, it can be inferred that when the coupling current due to IEMI exceeds the threshold value, it flows through the internal equipment line, causing a malfunction and subsequent failure. The results of this study can be applied to basic data for equipment protection, and effect analysis of intentional electromagnetic interference.

• Electrical & Electronic Materials
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• v.9 no.8
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• pp.783-788
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• 1996

In this paper, the high-$T_c$ , superconductor (HTS) microstrip patch antenna which is directly coupled to a microstrip transmission line is designed and the numerical solution which evaluate near electromagnetic field of HTS antenna is presented. This solution uses the interpolation function with the vector edge triangular element. The advantage of this element is the elimination of spurious solutions attributed to the lack of enforcement of the divergence condition. The results of this method have a good agreement with $TM_10$ mode in HTS microstrip patch antenna and show that the computation of resonant length considering the fringing capacitance effect at radiating edge are proper.

• Journal of the Optical Society of Korea
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• v.8 no.3
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• pp.137-146
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• 2004

A new method of obtaining the eigenmode of an anisotropic planar waveguide is studied. The planar waveguide can be composed of an arbitrary number of isotropic or uniaxially anisotropic layers, provided all the optical axes arc lying in the incidence plane. Since the equation of motion for the TE mode is not different from that for the TE mode in an isotropic planar waveguide, only the equation of motion for the TM mode is of any concern. For this kind of device structure, the Maxwell's equations can be solved for one component of the electric field and one component of the magnetic field. The resulting coupled set of equations is linear in the propagation constant and the eigenmode can be easily obtained using canned numerical routines.