• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.39-45
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• 2002

A new EMI estimation technique concerned with a PDP system is presented. A physical circuit model is developed which can fairly well describe the AC-PDP system. EMIs of the PDP system are quantitatively determined by combining circuit model and Hertzian dipole antenna model. The simulation results are experimentally verified with the test panel. The AC PDP system was measured in the frequency range of 30MHz~300MHz in a semi-anechoic chamber, according to CISPR 13 code. Thereby, it is shown that the proposed technique can be usefully employed for EMI reduction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.426-435
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• 2002

In this paper we present an indoor propagation model for indoor wireless LAN service in the ISM band. We primarily use a 3D ray tracing as well as a patch scattering model in order to take into account the indoor fixtures. Therefore input parameters such as indoor environment parameters and antenna's types, polarizations are considered. As the results, we present fading characteristics and rms delay spread from time delay spread. In order to investigate the accuracy of the presented model, comparisons of predictions with measurement and simulations are performed in indoor wireless LAN service environments. The results show that measurements and simulations are very similar. Therefore in this paper, the effect of presented indoor propagation model is confirmed.

• ETRI Journal
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• v.39 no.2
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• pp.234-244
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• 2017

Research interest in three-dimensional multiple-input multiple-output (3D-MIMO) beamforming has rapidly increased on account of its potential to support high data rates through an array of strategies, including sector or user-specific elevation beamforming and cell-splitting. To evaluate the full performance benefits of 3D and full-dimensional (FD) MIMO beamforming, the 3D character of the real MIMO channel must be modeled with consideration of both the azimuth and elevation domain. Most existing works on the 2D spatial channel model (2D-SCM) assume a wide range for the distribution of elevation angles of departure (eAoDs), which is not practical according to field measurements. In this paper, an optimal FD-MIMO planar array configuration is presented for different practical channel conditions by restricting the eAoDs to a finite range. Using a dynamic network level simulator that employs a complete 3D SCM, we analyze the relationship between the angular spread and sum throughput. In addition, we present an analysis on the optimal antenna configurations for the channels under consideration.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.2
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• pp.71-77
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• 2020

KRS which is subsystem of Korea Augmentation Satellite System (KASS) performs a role of collecting and monitoring GPS signals. In order to generate the accurate correction message, the site which meets the requirements should be selected and verification to meet each requirement should be accompanied. When the sites are selected, the environmental considerations are EMI, clear horizon (CH) and multipath. Of these, EMI and CH can be checked for satisfaction by instrumentation, but multipath error is difficult to predict. Therefore, multipath error analysis for the installation position of actual antenna at each KRS site should be preceded, and multipath scenario should be generated for each location to analyze the effects of the resulting system performance. In this paper, based on satellite signals collected from each KRS sites, the method for analyzing multipath error in each KRS sites is described, and the multipath error is analyzed. Also to perform an analysis of the effects on system performance due to multipath error, multipath error modeling is performed for the generation of simulation scenarios.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.470-474
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• 2006

This dissertation discuses about a ferrite core plasma source using low operating frequency without sputtering problem by the stored electric field. Compared with the conventional RF power system with 13.56MHz switching frequency, the proposed plasma power system is only separated at 400kHz, so that it makes possible to use of low cost switching elements, PWM control and soft switching. Moreover, it could improve the coupling efficiency for plasma and antenna by using the ferrite core in order to transfer the energy of the load This dissertation tried to analyze new plasma generation method for the plasma generation system by modeling the plasma load and grafting the concept of impedance matching in order to interpret it with the formula This dissertation verified the ferrite core inductive coupling plasma source authorized for 400kHz of low frequency power by applying to the semi-conductor ash process thru the measurement of ash capacity and uniformed plasma distribution on the actual wafer.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.134-141
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• 2008

We have developed a numerical model for a remote ICP(inductively coupled plasma) system in 2D and 3D with gas distribution configurations and confirmed it by plasma diagnostics. The ICP source has a Cu tube antenna wound along a quartz tube driven by a variable frequency rf power source($1.9{\sim}3.2$ MHz) for fast tuning without resort to motor driven variable capacitors. We investigated what conditions should be met to make the plasma remotely localized within the quartz tube region without charged particles' diffusing down to a substrate which is 300 mm below the source, using the numerical model. OES(optical emission spectroscopy), Langmuir probe measurements, and thermocouple measurement were used to verify it. To maintain ion current density at the substrate less than 0.1 $mA/cm^2$, two requirements were found to be necessary; higher gas pressure than 100 mTorr and smaller rf power than 1 kW for Ar.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_2
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• pp.673-680
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• 2012

Long-term GPS data analysis was performed in order to analyze the seasonal variation of tropospheric delay and the success rate of the ambiguity resolution. For this analysis, a total of 57 stations including 10 IGS stations in East Asia were processed together with double-differenced observables using Bernese GPS Software V5.0. The time span for this study ranges from 2002.0 to 2012.5 (10.5 years). The average baseline length is 339.0 km and the maximum reaches up to 2,000 km. The analysis is focused on two things: the annual variation of the tropospheric delay and the ambiguity resolution rate. The tropospheric delay is closely related to the weather condition, especially relative humidity, therefore it was estimated that the maximum would be in summer, while reaching its minimum in winter with the apparent seasonal variations. On the contrary, however, the success rate of the ambiguity resolution shows the opposite pattern: its maximum was in winter and minimum in summer. The fact seems to be induced by the surrounding conditions; that is, the trees thick with leaves near the GPS antenna interfere with GPS signals in summer. This seems to confirm partly that there is a distinct trend in the decreasing success rate since 2006 because the trees are growing every year. It is necessary to eliminate the factors that degrade the GPS quality and the tropospheric modeling for Korea needs to be studied further.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.3
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• pp.342-347
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• 2003

It is essential to develop an algorithm for the estimate of link travel velocity and for the supply and control of travel information in the context of intelligent transportation information system. The paper proposes the fuzzy logic based prediction of link travel velocity. Three factors such as time, date and velocity are considered as major components to represent the travel situation. In the fuzzy modeling, those factors were expressed by fuzzy membership functions. We acquire position／velocity data through GPS antenna with PDA embedded probe vehicles. The link travel velocity is calculated using refined GPS data and the prediction results are compared with actual data for its accuracy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.602-608
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• 2002

The flexible structure like solar array and antenna in spacecraft shows very sensitive responses to the inner or outer disturbance and noise. And the spacecraft becomes more complex and larger as it has various mission and role. But since the spacecraft need to have the limited mass, the thin and light material should be selected and this necessity induces the decrease d natural frequency and structural stiffness. It reduces the ability of adapting to the disturbance and induces the structural unstability. Certainly, the disturbance does not only make the structural unstability, but also give the bad effect to the precise attitude control. So it is necessary to control the vibration in the space. In this paper, the flexible structure control modeling with piezo sensor and piezo actuator is developed. The model uncertainty of damping ratio is overcome by robust control. The system equation is induced by the finite element method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.8-15
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• 2007

This paper presents the radiation rate formula due of a inclusion of a series capacitor and shunt inductor in a unit cell for the right/left-handed transmission line (RLH-TL). The equivalent circuit for a RLH unit cell considering radiation effects is presented and analyzed in terms of the Bloch impedance and dispersion diagram. It has been found that when two radiation rates are identical, the Blockimpedance reduces to the characteristic impedance of the host conventional RH-TL. Besides, design equations for a unit cell for a specific phase shift at a given frequency are provided. The method of realizing uniform excitation along the RLH-TL is also proposed for antenna applications.