• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1660-1663
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• 2003

This paper present the characteristics of radiation pattern of microstrip slot antenna on the ground plane fed by microstrip line. It is proposed for resonance frequency at 10 GHz. We will analysis two shape of slot antenna; double L-shape slot antenna and U-shape slot antenna. In this case, we will compare far-field radiation pattern of two shape slot antenna. Far-field radiation pattern of double L-shape slot antenna is bi-directional nevertheless U-shape slot antenna is uni-directional. The microstrip slot antenna is propose to analyze far-field radiation pattern for use in the wireless communication systems

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.689-697
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• 2007

This thesis suggests ways on how to enhance handset radiation power under head phantom condition. Generally, peak EIRP(Effective Isotropic Radiated Power) is used to measure the radiation performance. TRP is more effective to represent indication of mobile radiation performance in the field than EIRP. In this case, we measure the TRP as an index of radiation power. The factors which effect TRP are antenna length, antenna position, folder angle and ground connection method. More detailed analysis is performed over these items. Significant item is ground connection method between main PCB and folder GND. Using the FPCB we connect main GND to folder GND through the hinge near the antenna. The result is that TRP attenuation is decreased about 5 dB under head phantom condition.

• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.363-368
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• 2011

The DGPS transmits the enhancement signal to GPS using the medium frequency band. The NDGPS service that covers the Korean peninsula has been started since 2009. The service area of ocean-based DGPS(maritime-DGPS) reference stations covers the 100NM, but land-based DGPS(land-DGPS) covers 80km service area less than that of maritime DGPS. The DGPS's antenna has the top-loaded monopole antenna type. Top-loaded monopoles are the logical antennas to be used in order to get a low profile antenna and a performance according to the broadcaster and communication needs. The antenna needs to get the ground plane with good conductivity characteristics and flat ground plane without obstacle near to the transmitting antenna. In this paper, the radiation characteristics of an equivalent MF antenna are analyzed in view points of the ground conductivity and the ground plane with obstacle near to the antenna.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.2
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• pp.24-29
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• 2015

In this paper, a microstrip antenna with isoflux radiation patterns is presented for Low Earth Orbit(LEO) medium-sized satellites. Because of making isoflux patterns, the ground of proposed antenna under the patch was transform into a trapezoid for adjusting fringing field between the patch and ground. Next, the cavity walls were located at end of the ground for reducing back radiation. The proposed antenna was designed to receive S-band uplink(2.025 ~ 2.110 GHz) and the dimensions of the designed antenna with the ground are $160mm{\times}160mm{\times}40mm$ ($1.1{\lambda}{\times}1.1{\lambda}{\times}0.3{\lambda}$, ${\lambda}$ is the free-space wavelength at 2.068 GHz). Measured -10 dB bandwidth was 90 MHz(4.4 %) and it covers the required system bandwidth. Also, measured 3 dB axial ratio was 18 MHz(0.9 %). On the other hand, measured radiation patterns were isoflux patterns and its measured gain was 5.31 dBi at E-plane $46^{\circ}$ in the y-axis pol.

• Asian Journal of Atmospheric Environment
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• v.10 no.4
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• pp.179-189
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• 2016

Here we evaluated the effect of using water retentive pavement or WRP made from fly ash as material for main street in a real city block. We coupled computational fluid dynamics and pavement transport (CFD-PT) model to examine energy balance in the building canopies and ground surface. Two cases of 24 h unsteady analysis were simulated: case 1 where asphalt was used as the pavement material of all ground surfaces and case 2 where WRP was used as main street material. We aim to (1) predict diurnal variation in air temperature, wind speed, ground surface temperature and water content; and (2) compare ground surface energy fluxes. Using the coupled CFD-PT model it was proven that WRP as pavement material for main street can cause a decrease in ground surface temperature. The most significant decrease occurred at 1200 JST when solar radiation was most intense, surface temperature decreased by $13.8^{\circ}C$. This surface temperature decrease also led to cooling of air temperature at 1.5 m above street surface. During this time, air temperature in case 2 decreased by $0.28^{\circ}C$. As the radiation weakens from 1600 JST to 2000 JST, evaporative cooling had also been minimal. Shadow effect, higher albedo and lower thermal conductivity of WRP also contributed to surface temperature decrease. The cooling of ground surface eventually led to air temperature decrease. The degree of air temperature decrease was proportional to the surface temperature decrease. In terms of energy balance, WRP caused a maximum increase in latent heat flux by up to $255W/m^2$ and a decrease in sensible heat flux by up to $465W/m^2$.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.379-386
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• 2018

A heat-sink has been widely used to cool down the heat generated from an electronic device, but it can bring unwanted electromagnetic radiation which may cause EMI problems. We propose a systematic method to reduce the electromagnetic radiation by using the multiple grounding technique based on the grounding criteria and the theory of characteristic mode analysis. Our proposed method provides the insight to find the specific grounding positions which can be effectively reduced the radiation from the heat-sink. Numerical experiments are accomplished to validate this approach.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.845-848
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• 1999

We designed and fabricated partially shorted QMSAs(Quarter-Wavelength Microstrip Antennas) for 850［MHz］band on various Copper-clad Laminates substrates (TACONIC company), where the width of the radiation patch is identical with that of the ground plane and the radiation patch is partially shorted to the ground plane. The resonant frequencies and the return losses according to the electrical thickness were measured by reducing the PSW (Partially Shorted Width) to 0［mm］. As a result, a good characterized antenna with an average 11% reduced resonant length and a return loss -15.86~-30.68［㏈］ was obtained when the total PSW was in the range of 70% of radiated patch width, compared to the conventional QMSA.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.401-404
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• 2001

We designed and fabricated symmetrical partially shorted MSAs for 850 MHz band on various Copper-clad Laminates substrates, where the width of the radiation patch is identical with that of the ground plane and the radiation patch is partially shorted to the ground plane. The resonant frequency, return loss and input impedance due to the permittivity(2.5, 3.5, 10.0) and thickness(0.76~1.57 mm, 6 types) were measured by reducing the PSW (Partially Shorted Width) to 0 mm. As a result, good characterized antennas with average 11% reduced resonant length and return loss 7.288~29.445 dB were obtained when the total PSW was in the range of 70% of radiated patch width, compared to the conventional λ/4 MSA.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.81-86
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• 2007

Spectral features of the seismic wave propagation from Odaesan Earthquake were evaluated based on the commonly treated random error between the observed data and the prediction values by the stochastic point-source ground-motion spectral model regarding the source, path and site effects. Radiation pattern of the error according to azimuth angle was found to be similar to the theoretical estimate. It was also observed that the spatial distribution of the errors was correlated with the geological map and the Q0 map which are indicatives of seismic boundaries.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.75-80
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• 2021

In this paper, a dual-band Koch Snowflake antenna is proposed for wireless communication systems. Fractal geometry, CPW-feed and stepped ground planes are used to improve the impedance bandwidth. By properly introducing a hexagonal split-ring slot to radiating element, a lower frequency band is generated. The proposed structure is fabricated and tested. Experiment results exhibit dual-band of 0.73-0.98 GHZ and 1.6-3.1 GHz which makes this antenna suitable candidate for GSM900, GSM1800, UTMS2100, Wi-Fi 2400 and LTE2600 bands. In addition, a good radiation pattern, a satisfactory peak gain and a radiation efficiency, which reaches 95%, are achieved.