• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.95-100
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• 2004

This paper represents the development of a CLS(Control Loading System) for a target a airplane (KT-1) with mechanical linkage reversible flight control system. The system is composed of mechanical frame, controller, sensing part to measure the force from the stick, driving system generating the reaction forces. The DS1103 DSP(Digital Signal Processor) of the dSpace Corp. was used as the controller. The control algorithm of the CLS and the operational environment including monitoring software and evaluation tools are described. The evaluation of the system was conducted according to the requirement specification. The results of the test were analyzed by comparing with the actual data of the target airplane.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2206-2212
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• 2017

When it comes to naval surface warfare, the probability of detection is an important factor in survivability and the Radar Cross Section(RCS) is a major parameter. In this paper, the RCS reduction technology of the Radar Absorbing Material(RAM) method is carried out for the general frequency range for naval warfare. We set the analysis model with the simplified ship model and the wide band metamaterial which is high-tech radar absorbing materials is selected for the RAM method. The modeling of the wide band metamaterial composed of an MIK surface which has the wide band resonant properties and flexible substance and the electromagnetic absorptions and reflections of the wide band metamaterial has been simulated to explore the performance. Also, the wide band metamaterial is compared with the paint absorber to analyze RCS reduction in terms of RCS values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.8
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• pp.437-444
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• 2014

In this paper, we propose a path loss model with the multiple antennas and doppler shift for high speed railroad communication. Path loss model is very important in order to design consider diverse characteristic in high-speed train communication. Currently wireless communication systems use the multiple antennas in order to improve the channel capacity or diversity gain. However, until recently, many researches on path loss model only consider geographical environment between the transmitter and the receiver. There is no study about path loss model considering diversity effect and doppler shift. In order to make average residuals considering doppler shift we use tuned free space path loss model which is utilized for measurement results at high speed railroad. The environment of high speed rail is mostly at viaduct and flatland over than 50 percent. And in order to make average residuals considering multiple antenna we use theoretical estimation of diversity gain with MRC scheme. proposed model predict loss of received signal by estimating average residuals between diversity effect and doppler shift.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.8
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• pp.474-480
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• 2014

In this paper, we propose a study for the next generation terrestrial broadcasting technology based on SFN(Single Frequency Networks), which applies multiple receiving antenna to improve receiving performance of cloud transmission system. By applying multiple receiving antenna, the received broadcast signals at the boundary of different SFN broadcasting area could be modelled by distributed MIMO system. Due to the interference cancellation effect of the MIMO detector, the proposed scheme could suppress the adjacent area interference more efficiently compared to the single receiving antenna case. Simulation results show that receiving performance can be improved dramatically in overlapping area of SFN by applying multiple antenna receivers in cloud transmission system.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.600-602
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• 2006

Some abnormal signals diagnostics and analysis through an important equivalent circuits modeling for passive elements under severe accident conditions have been performed. Unlike the design basis accidents, there are inherently some uncertainties in the instrumentation capabilities under the accident conditions. So, the circuit simulation analysis and diagnosis methods are used to assess instruments in detail when they give apparently abnormal readings as an accident alternative method. The simulations can be useful to investigate what the signal and circuit characteristics would be when similar to a variety of symptoms that can result from the environmental conditions such as high temperature, humidity, and pressure condition. In this paper, a new simulator through an analysis of the important equivalent circuits modeling under temperature accident conditions has been designed, the designed simulator is composed of the LabVIEW code as a main tool and the out-put file of the Multi-SIM code as an engine tool is exported to in-put file of the LabVIEW code. The procedure for the simulator design was divided into two design steps, of which the first step was the diagnosis method, the second step was the circuit simulator for the signal processing tool. It has three main functions which are a signal processing tool, an accident management tool, and an additional guide from the initial screen. This simulator should be possible that it could be applied a output signal analysis to some transient signal by variation of the resistance passive elements in the R-L-C equivalent circuit modeling under various degraded conditions in NPPs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.655-662
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• 2016

Accurate stopping control is important for trains, especially now that many train stations are equipped with platform screen doors. Various algorithms have been proposed for accurate stopping control. However, most metro trains in South Korea use classic control algorithms such as PID control because other algorithms are too complex to realize. PID control has merits of simple structure and operation. However, PID control sometimes fails, and much time is needed to find the proper coefficients due to the long control period and the brake delay. We propose a control algorithm that uses a Kalman filter. The Kalman filter estimates the states at the time when braking starts. Then, a suitable control input is derived for proper control. System modeling and a computer simulation were performed with consideration of the brake properties and the period of the control system. The superiority of the proposed control algorithm is shown by analyzing stop errors.

• Geophysics and Geophysical Exploration
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• v.14 no.2
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• pp.152-157
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• 2011

The small-loop electromagnetic (EM) method is one of the rapid and non-destructive geophysical methods and has been used widely for many geophysical investigations, particularly for shallow engineering and environmental surveys. Especially in the shallow marine environment, the small-loop EM technique is very effective because of rapid and convenient data acquisition, large signal and low noise level. However, the method has been rarely applied in the very conductive marine environment since it's penetration or investigation depth might be considered too low. In this study, we demonstrated that the small-loop EM method can be effectively applied in the extremely conductive marine environment through the analysis of 1D small-loop EM data. Furthermore, we confirmed that the resistivity distribution under the sea bottom can be quantitatively predicted from the 1D inversion results of synthetic and field data.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.65-73
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• 2013

Ground-coupled heat pump system has attracted attention as a promising renewable energy technology due to its improving energy efficiency and eco-friendly mechanism for space cooling and heating. Pipes buried in the ground play a role of direct thermal interaction between circulating fluid inside the pipe and surrounding soils in the geothermal exchange system. However, both complexities of turbulent flow coupling thermal-hydraulic phenomena and very long aspect ratio of the pipe make it difficult to model the heat exchange system directly. Energy balance for fluid flow inside the pipe was derived to model thermal-hydraulic phenomena, and one-dimensional pipe element was proposed through Galerkin formation and time integration of the equation. Developed element is combined to pre-developed FEM code for THM phenomena in porous media. Numerical results of Thermal Response Test showed that line-source model overestimates equivalent thermal conductivity of surrounding soils due to thermal interaction between adjacent pipes and finite length of the pipe. Thus, inverse analysis for the TRT simulation was conducted to present optimal transformation matrix with utmost convergence.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.170-178
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• 2010

In this paper, we propose the modeling of the power/ground plane which includes complex dielectric permittivity and loss tangent for the power/ground coupled noise. In order to estimate the effects of the dielectric substrate for the coupled noise, we used full-wave simulators, HFSS(High Frequency Structure Simulation) and MWS(MicroWave Studio). The simulated results for the commercial substrates are compared with the measured values. TLM(Transmission Line Method) was used for the calculation of power plane impedance using Debye model which depicts the dielectric loss of PCB. Finally, impedance from proposed circuit model showed very good coincidence to the measured data.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.41-49
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• 2017

Theoretical modelling and computational results for frequency coordination are presented over mobile base station and fixed wireless systems in urban or sub-urban area. Computational results with key parameters needed for interference analysis are performed and discussed in terms of system characteristics, propagation model, protection ratio, frequency dependent rejection, and discrimination angle with signal-interference plane. Based upon minimum coupling loss methodology, calculated interference powers of victim receiver for assumed system parameters are compared with maximum allowable interference power derived from protection ratio as functions of discrimination angle and distance including height-gain model in urban or sub-urban area. The proposed method is applicable for technical analysis on co-existence or interoperability for the various wireless systems, mandatory for frequency coordination or reallocation process.