• Economic and Environmental Geology
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• v.20 no.1
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• pp.77-82
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• 1987

An analysis is made for the relative effectiveness in detecting a subsurface thin layer by four electromagnetic depth sounding systems; horizontal coplanar loops, perpendicular loops, vertical coplanar loops and vertical coaxial loops. The moduli and phases of mutual coupling ratios over a three-layered earth for the four systems are evaluated rapidly by the related convolution technique. Root mean square differences between the responses from the three-layered and the homogeneous earths are used to compare the relative effectiveness of the systems quantitatively. Comparing the all systems, it is found that the perpendicular loop system appears to be the most superior to the other systems.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.288-293
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• 2003

In this paper, Filter could use to IMT2000 repeater using resonator of Comb-line form that has waveguide structure and designed. Coupled resonators designed using slot in wall between resonators to compact. 5-stage resonators have equal structure and input and output part was optimized to get into minimum impedance. Band pass filter characteristic satisfied design condition as result that used Chebyshev function that have 0.2 dB ripple and analyze using simulation tool.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.676-685
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• 2001

In this paper, the design method of the meander-coupled Wilkinson power divider with slit is proposed. Because the electrical performance of this structure is varied with each coupling distance and the slit's size, a tedious design work, which is done by trial and error correction, is required to determine the values of parameters for the best suitable operation. To solve this problems, therefore, an experimental design formulas for optimum performance are presented by curve fitting, under the desired center frequency($f_0$). As the example using the proposed design equation, we designed and fabricated the meander-coupled divider at $f_0$=1.5 GHz. It has better electrical performance and measured results also agrees very well that of the simulated. From these observation, it can be concluded that the obtained design formulas are useful for design of this divider.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.713-721
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• 2001

In this paper, parasitic patches gap-coupled microstrip antenna and stacked microstrip patch antenna combined with parallel coupled lines, which are a kind of wideband impedance matching network, are proposed to get the wider bandwidth. The iterative method using a distributed network is proposed to design the parallel coupled lines as a wideband impedance matching network. Measurements show that the proposed antennas provide wider bandwidths ~1.6 times and ~1.5 times those of conventional parasitic gap-coupled microstrip patch antenna and stacked microstrip patch antenna. In addition, measured radiation patterns show no serious variation of radiation patterns though the parallel coupled lines is added. The antenna gain is, however, lowered about 1 dB and 0.5 dB by the coupling loss in the parallel coupled lines.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.951-959
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• 2015

Ground radiation antenna in mobile devices is becoming an issue for satisfying both miniaturization and high performance. Ground radiation antenna controls the characteristic mode of the ground plane and couples this mode with the ground radiation antenna, thereby having good radiation performance. In this paper, the characteristic mode theory and applications of ground radiation antenna will be introduced. The operating mechanism of single band, wideband and dual-band ground radiation antennas are studied.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.439-449
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• 2011

The temperature distribution and subsequent permanent deformation of SS400 carbon steel plate subjected to an induction-based line heating process were studied by a numerical method involving coupled 3-D electromagnetic-thermal-structural analysis. The numerical study revealed that the amount of permanent deformation is strongly related to the Joule loss caused by such process conditions as input power and moving speed of the heat source. To validate the numerical analysis results, line heating experiments were carried out with a high frequency(HF) induction heating(IH) equipment capable of bending thick plate with the moving accuracy of ${\pm}0.1mm$ in heating coil position. The amount of permanent deformation increased with decreasing moving speed and increasing input power.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.253-264
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• 1998

In this paper, a design method for directional couplers using bilevel microstrip substrates is proposed. This kind of broadside-coupled coupler provides large coupling factors and broadband characteristics which can not be provided by conventional edge-coupled couplers. Physical dimensions needed for design are obtained by numerical analysis of characteristic parameters of the coupler using the least squares residual method, a kind of variational method, and an eigenvalue problem analysis method. A 3[dB] directional coupler is designed by the proposed method at the center frequency of 1 GHz, built, and tested. The validation and accuracy of the method are confirmed by comparing the numerical results with the experimental results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.187-195
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• 1999

A series feedback DRO operating at 3.2 GHz applicable to the spectrum analyzer as the second local oscillator, is designed and fabricated. We can obtain a low noise by utilizing the small signal S-parameter of the transistor and adjusting the reflection coefficient from the coupling coefficient between dielectric resonator and microstrip line. The results show that output power is 10.50 dBm, a stable low phase noise is -116 dBc/Hz at a 10 kHz offset frequency and a harmonic characteristic is 19.33 dBc.

• Journal of electromagnetic engineering and science
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• v.4 no.1
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• pp.30-36
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• 2004

We determined equivalent circuit parameters of a 1.5 cell S-band RF gun cavity from the resonant characteristics of its decoupled cavities(half cell and full cell) using the code SUPERFISH. Equivalent circuit parameters of the 1.5 cell RF gun cavity resonated in the 0-mode were obtained easily from the circuit parameters of each decoupled cavities. In order to obtain equivalent circuit parameters for the $\pi$ -mode cavity, we calculated the differences of the resonant frequencies and the equivalent resistances between the 0- and $\pi$ -modes with slight variations of the radius and thickness of the coupling iris. From those differences, we obtained R/Q value and equivalent resistance of the $\pi$ -mode, which are directly related to the equivalent circuit parameters of the coupled cavity. Using calculated R/Q value, we can express equivalent inductance, capacitance and resistances of the RF gun cavity resonated in the $\pi$ -mode, which can be useful for analyzing coupled cavities in a steady state.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.4
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• pp.382-389
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• 1997

We present the results on the applicability of the polycrystalline AIN thin films for a surface acoustic wave filter operating at 800 MHz frequency. The films show the FWHM of 3 .deg. from th X-ray rocking curve, which indicates that the c-axis of the films is pre- ferentially oriented along the growth direction. The fabricated band pass filters exhibit the center frequency of 865 MHz with 3dB band-width of 45 MHz. From the measured frequency response, the electro-mechanical coupling constant of 0.8% and the SAW velocity of 5,709 m/s are obtained. Thus, we conclude that the sputtered AIN films are feasible for the fabrication of uper UHF band SAW filters.