• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.688-697
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• 2008

In this paper, an analysis method for indoor optical wireless channel properties based on photon model is presented for characterization of communication environment. In contrast to radio waves, optical waves have very short wave-lengths and very high frequencies, so that material properties become important. Channel models including diffuse reflections and absorption effects due to material surface textures make conventional electromagnetic wave analysis methods based on ray tracing consume enormous time. To overcome these problems, an analysis method using photon model is presented that approximates light intensity by a density of photons. The photon model ensures that simulation time is within a predictable limit.

• The Journal of Information Technology
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• v.8 no.2
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• pp.77-84
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• 2005

In this paper, electromagnetic scattering problems by a resistive strip grating with tapered resistivity on a grounded dielectric plane according to strip width and spacing, relative permittivity and thickness of dielectric layers, and incident angles of a electric wave are analyzed by applying the Fourier-Galerkin Moment Method known as a numerical procedure. The boundary conditions are applied to obtain the unknown field coefficients and the resistive boundary condition is used for the relationship between the tangential electric field and the electric current density on the strip. The resistivity of resistive strips in this paper varies from zeroes at one edge to infinite at the other edge, then the induced surface current density on the resistive strip is expanded in a series of Jacobi polynomials of the order ${\alpha}=0.2,\;{\beta}=-0.2$ as a orthogonal polynomials. The numerical results of the geometrically normalized reflected power in this paper are compared with those for the existing perfectly conducting strip. The numerical results of the normalized reflected power for conductive strips case with zero resistivity in this paper show in good agreement with those of existing papers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2059-2064
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• 2011

The DGPS systems that is a GPS augmentation system were installed for ocean- and land-service. The ocean-based reference station of 11 site and the land-based reference station of 6 sites are operating for ocean- and land-service. Although the land-based reference stations provide the output power of 500W, the service shadow regions are occurred due to mountain lands and building area. In this paper, the service coverages for land-based reference stations are analyzed in conditions of output power enhancements of reference station. The service shadow areas are deduced from service coverages of land-based reference stations and ocean-based reference stations. The medium frequency-band wave propagation models are considered as DGPS wave propagation model. The service coverages are analyzed by considering the compensated ground surface-conductivity.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.385-394
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• 2021

In this paper, a new equation of electromagnetic wave transmission matrix was proposed to calculate the reflected power and transmitted power for the multi-layered planar lossy structure. The applied human leg was modeled as a four-layer planar structure of skin, fat, muscle and bone. The complex dielectric constant to consider the loss of each of these layers was calculated using the 4-pole cole-cole model parameter. When electromagnetic waves were incident on the skin surface, total reflected and transmitted power, and human body loss were calculated for a frequency band of 0.1 to 20.0 GHz. And for various muscle thicknesses, the power reflected only from the outermost bone and re-radiated from the skin was calculated. It was confirmed that at the muscle thickness of 3.0 mm and the frequency of 4.6 GHz the return loss was -6.13 dB, which was 3.42 dB lower than the average value.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.245-249
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• 2010

Now normally using a contact method of vehicle Inhibitor Switch that is use direct voltage level signal. This method is good solution for signal deliverly. but The contacted method have a short lifetime because of deterioration of contact surface. so we suggest to non-contacted method using magnetic sensor. The magnetic sensor is used to non-contacted method that is solution for problem of contacted method. In this paper using that of magnetic sensor feature, so we applied to Vehicle Transmitter switch that of non-contacting method. Sensor voltage outputs have variable electric potential that normally 0 mV to 150 mV, and it is depend on Switch Angle. we used two differential sin wave for switching of 5 state signal.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.37-44
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• 2012

This paper describes a compact and novel wireless vital sign sensor at 2.4 GHz that can detect heartbeat and respiration signals. The oscillator circuit incorporates a planar resonator, which functions as a series feedback element as well as a near-field radiator. The periodic movement of a human body during aerobic exercise could cause an input impedance variation of the radiator within near-field range. This variation results in a corresponding change in the oscillation frequency and this change has been utilized for the sensing of human vital signs. In addition, a surface acoustic wave (SAW) filter and power detector have been used to increase the system sensitivity and to transform the frequency variation into a voltage waveform. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signs very accurately.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1752-1758
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• 1989

For many different types of apertures the diffraction phenomenon on the electromagnetic wave is analyzed by unsing Kirchhoff and Fresnel's diffraction theory. The signal intensity in variation of aperture's parameters is numerically calculated by a computer. To obtain the experimental data many types of apertures were made on an acryl board on which a special materical Elecoat was painted for preventing some reflections on the board surface and transmissions through it. Two Yagi antennas were used for a transmitting and receiving antenna and the frequency was 820MHz. The theoretichal values agreed reasonably with experimental data and these results will be used for a system design in the mobile communication between many buildings in the middle of a city.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.563-567
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• 2004

In this paper, a remote temperature sensor based on surface acoustic wave is introduced and the issues on design, manufacturing, and test of the sensor are addressed. SAW sensors having single and double electrode are prepared on the 128$^{\circ}$ YX-LiNbO$_3$ Substrate. The frequency responses of SAW sensors on the temperature change are compared. To measure the change of center frequency, two center frequencies on the 3dB and 20dB are measured and compared. Since the center frequency on the temperature change from -30$^{\circ}C$ to 80$^{\circ}C$ is linearly changed, the SAW sensor is applicable to the temperature sensor.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.393-394
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• 2007

In this study, to minimize the above effect Zinc Oxide(ZnO) thin films on Si(100) substrate were deposited by RF magnetron sputter with changing sputtering conditions such as Ar/$O_2$ gas ratios, RF power, substrate temperature, chamber prsssure and target-substrate distance. To analyze a crystallographic properties of the films, ${\Theta}/2{\Theta}$ mode X-ray diffraction, rocking curve and Alpha-step were performed. SAW filters were fabricated to evaluate the feasibility of ZnO thin film as a piezoelectrical materials and the processes of ZnO SAW filters using etch and lift-off were compared.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.947-952
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• 2001

In this paper, a wideband SAW convolver using a parabolic horn waveguide was designed and its characteristics were investigated. The convolver was made with parabolic horn waveguide at compression ratio 9:1 for reducing propagation loss and for improving convolution efficiency between two input IDTs of center frequency 193.78 ㎒. The SAW convolver utilizing acoustic nonlinearities of piezoelectric material demonstrated that it can provide large S/N ratio and can be use for programmable matched filter(PMF) in spread spectrum communication system.