• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.2
• /
• pp.173-180
• /
• 2003

Effects of the electric conductivity of particles were studied for the aggregation process of charged particles with a Brownian dynamic simulation in the free molecular regime. A periodic boundary condition was used for the calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered two extreme cases, a perfect conductor and a perfect nonconductor. The electrostatic force on a particle in the simulation cell was considered as a sum of electrostatic forces from other particles in the original cell and its replicate cells. We assumed that aggregates were only charged with pre-charged primary particles. The morphological shape of aggregates was described in terms of the fractal dimension. The fractal dimension for the uncharged aggregate was D$_{f}$= 1.761. However, the fractal dimension decreased from 1.694 to 1.360 for the case of the perfect conductor, and from 1.610 to 1.476 for the case of the perfect nonconductor, with the increase of the average number of charges on the primary particle from 0.2 to 0.3. These values were smaller than that of the centered charge case.e.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.1
• /
• pp.44-52
• /
• 2014

In this study, the influence of the near field, far field and radiation directivity of microstrip patch antenna when is used mushroom EBG(Electromagnetic Band Gap) as ground is investigated. Using characteristic of dispersion diagram of mushroom EBG, we calculated forbidden band(2.36GHz-2.85GHz) given mushroom type EBG microstrip antenna(2.45GHz) having 2-layer EBG that is operating within forbidden band. In oder to conform performance enhancemen of antenna using EBG ground, we have compared with the antenna using PEC(Perfect Electric Conductor) ground. We could know about 2.74dB increment of the radiation directivity, because EBG can suppress surface wave that is generated at interfaces of the dielectrics-conductor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.3
• /
• pp.229-238
• /
• 2016

In this paper, we have studied isolation enhancement using a suppression of surface wave to improve performance of array antenna. To reduce isolation between elements of array antenna, perfect magnetic conductor(PMC) and SOFT-surface is designed and located at center of ground plane, isolation and gain is simulated by commercial full wave simulator(HFSS). As a result, isolation of more than 40 dB and gain improvement of 2.2 dBi are obtained at E-plane array in case of both PMC and SOFT-surface. At H-plane array, air coupling is dominant compared to coupling by surface wave. It is conclude that this study is useful for design of compact array antenna and performance improvement of array antenna.

• Korean Chemical Engineering Research
• /
• v.54 no.4
• /
• pp.568-573
• /
• 2016

We investigated the charging characteristics of a conducting solid sphere (glassy carbon sphere) comparing with that of a water droplet and check the applicability of the perfect conductor theory. For the systematic research, sphere size, applied voltages, viscosity of the medium were changed and the results were compared with that of corresponding water droplets and the perfect conductor theory. Basically, a glassy carbon sphere follows the perfect conductor theory but the charging amount was lower as much as 70~80% of theoretical prediction value due to oil film formed between electrode and a carbon sphere. We hope this result provides basic understandings on the solid sphere contact charging phenomenon and related applications.

• Journal of the Optical Society of Korea
• /
• v.7 no.3
• /
• pp.180-187
• /
• 2003

A theoretical presentation by using a three-dimensional finite difference beam propagating method (3-D FD-BPM) for the evanescent coupling is offered with respect to the refractive indexes between a side-polished optical fiber and an infinitely planar waveguide with a conductor cladding (PWGCC). The PWG is suspended at a constant distance from an unclad fiber core and attached with a perfect conductor (PEC) on one side. The coupling and propagation of light are found to depend on both the relationship between the refractive index values of two structures and the configuration of the side-polished fiber used in the PWGCC. The spreading of light in the unconfined direction of a PWGCC is presented with the distribution of electric fields in xy - plane and the absolute amplitude of electric fields along the x and y axis. The power of the light propagation in a fiber decreases exponentially along the fiber axis as it is transferred to the PWGCC, where it is carried away.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.296_297
• /
• 2009

다층구조의conductor와 shield로 구성되는 HTS-cable의 교류손실 특성 연구를 위하여 2005년부터 실증시험 중에 있는 22.9kV, 50MVA, 100m급 KEPCO HTS-cable system에 사용된 케이블과 동일한 두개의 short-sample에 대하여DC 및 AC 특성을 실험적으로 조사하였다. KEPCO HTS-cable system에서처럼 shield전류를 conductor와 크기는 같게 하고 방향을 반대로하여 수주기동안 AC pulse전류를 인가했을 때, shield의 임계전류가 conductor보다 작음에도 불구하고 conductor-lead에 대하여 측정된 AC loss가 shield의 것과 비교하여 약 1.5배 큰 것을 알 수 있었다

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.11 no.5
• /
• pp.323-331
• /
• 1986

By solving the current distribution, natual frequencies, and the amplitude of natural modes about the perfect conducting scatterer of revolution are presented. Singularity expansion method is applied to slove the time-domain response based on the simplified E-field integral equation by the application of the extended boundary conditin for the perfect conductin scatterer of revolution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.3
• /
• pp.304-310
• /
• 2008

Generally U-slotted patch antenna with PEC(Perfect Electric Conductor) ground plane is used for mobile telecommunication. However the improvement of the bandwidth is required to enlarge the capability of mobile telecommunication, In this paper, U-slotted patch antenna with EBG(Electromagnetic Band-Gap) ground plane is proposed to enlarge thr bandwidth and its radiation characteristics are investigated. To conform the bandwidth improvement, two kinds of U-slotted patch antennas with EBG and PEC ground plane are designed, fabricated, and radiation characteristics are measured. It is shown that the proposed antenna is wider than U-slotted patch antenna with PEC ground plane in bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.10
• /
• pp.805-810
• /
• 2018

A coated perfect electric conductor(PEC) interface to reduce scattered fields can be efficiently modeled by using the impedance boundary condition. The self-dual integral equation(SDIE) proposed by Yan et al. may be an efficient multi-level fast multipole method (MLFMM) formulation for the impedance object. This equation can be applied to an inhomogeneous impedance material, but its accuracy can be degenerated when the material contains a PEC or perfect magnetic conductor(PMC) region. In this paper, we modify the original SDIE formulation for an inhomogeneous object containing a PEC or PMC region and numerically verify its accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.7
• /
• pp.1558-1563
• /
• 2013

In this paper, we analyze the radio propagation path loss characteristics for the vertical electric dipole radiation over the perfect electric conductor(PEC) ground plane. Most research have been performed about the electromagnetic analysis of vertical electric dipole in free space for time domain or frequency domain. But this paper present the radio propagation path loss over PEC ground plane in time domain under the assumption of the vertical electric dipole as a base station. From the simulated results, the ground plane effect can change the location of near field from transmitting antenna and the transient responses at mobile are calculated. The results of this paper can be applied to surface radar or signal processing applications.