• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.299-309
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• 2013

A comprehensive SAR(Synthetic Aperture Radar) simulation is considered to be a complicated task since a full knowledge of the signal propagation characteristics, antenna pattern, system internal errors and interference noises should be taken into account. In high resolution target application modes, the time varying nature of target RCS(Radar Cross Section) strongly affects the generated SAR images. In this paper, in-depth SAR simulations are performed and analyzed incorporating the STK tools and MATLAB software. STK provides realistic orbit parameters while its radar module helps to extract accurate radiometric parameters of ground targets. SAR raw data corresponding to a given target is generated and processed using MATLAB simulator. The performance is measured by PSLR(Peak Sidelobe Ratio) and ISLR(Integrated Sidelobe Ratio) for a point target, which can be used as reference parameters for accurate radiometric calibration. Finally, high resolution target simulations are performed by adopting time varying target RCS characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.7
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• pp.1032-1037
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• 2002

In this paper, derived monocycle pulse that application is possible within permission frequency band (3.1 ~ 10.6GHz) that establish in FCC. Also, PPM modulated TH IR system simulator is designed in AWGN environment. It is analyzed monocycle pulse specific property and system performance using simulator. Also, analyzed BER performances of IR system in multiple access interference environment using proposed parameters. According to result, application of possible pulse duration$(t_n)$ is very limited by 0.04~0.0326 ns in permission frequency range that establish in FCC. In the case of same pulse signal power, we could know that system performance changes by $N_s$ regardless of pulse duration. IR system that need high speed transmission more than 50 Mbps in multiple access interference environment could know that very serious performance decrease by multiple access Interference happens.

• 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 Broadcast Engineering
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• v.19 no.4
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• pp.510-520
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• 2014

By adopting the MAC(Media Access Control) protocol which enables to pack multiple MPDUs(MAC-level Protocol Data Units) into a single PPDU(Physical Layer Protocol Data Unit), IEEE 802.11n WLAN supports high throughput. Up to now, there have been a lot of existing channel information-based A-MPDU schemes dynamically determining the number of MSDUs according to the wireless channel condition information which is sent from the receiver to sender. However, the channel information-based scheme has a serious drawback having a high system overhead due to the frequent channel feedback information. To reduce the system overhead, the proposed BA-base dynamic A-MPDU scheme simply chooses the number of MSDUs to be retransmitted by not the frequent channel feedback information but the BA signal representing whether MPSUs belonging to the A-MPDU are received or not. Through NS-2(Network Simulator-2), we found that the proposed scheme had higher throughput and lower packet error rate than the existing fixed A-MPDU scheme.

• Journal of Biomedical Engineering Research
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• v.36 no.2
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• pp.48-53
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• 2015

Sudden infant death syndrome(SIDS) continues to be general cause of infant death. Also, apnea is supposed to be one of the main risk factor of SIDS. Therefore, Infant's respiratory monitoring and real-time apnea detection is very important to prevent SIDS. In this study, we proposed a non-contact home monitoring system for infant's respiration using Doppler radar in order to prevent SIDS. The respiration data were acquired from a commercialized baby simulator(Simbaby$^{TM}$) using a Doppler radar. To evaluate a performance of the proposed system, the simulator was placed in a supine and prone position and the chest belt was used simultaneously as a reference signal. As a result, correlation coefficients between respiration rates of Doppler radar and the chest belt in each position were 0.95(p < 0.001) and 0.98(p < 0.001), respectively. The averages of difference were $-0.29{\pm}5.21(mean{\pm}1.96{\cdot}$ standard deviation) in supine and $-0.12{\pm}3.05$ in prone from Bland-Altman analysis. The results indicated an excellent performance in detecting apnea with a sensitivity of 100% and a positive predictive value of 100% in each posture respectively. These results demonstrated that a proposed Doppler radar system is suitable for non-contact respiratory monitoring in order to prevent SIDS of infant.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.5
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• pp.108-116
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• 1989

The simulator described here-LOSIM(LOgic SIMulator)-was developed to verify the logic design for VLSI(Very Large Scale Integrated) circuits at mixed level. In this paper, we present a modeling approach to obtain more accurate results than conventional logic simulators [5-6,9] for general elements, functional elements, transmission gates and tri-state gates using eight signal values and two gignal strengths. LOSIM has the capability which can perform timing and hazard analysis by using assignable rise and fall delays. We also prosent an efficient algorithm to accurately detectdynamic and static hazards which may be caused by the circuit delays. Our approach is based on five logic values and the scheduled time. LOSIM has been implemented on a UN-3/160 workstation running Berkeley 4.2 UNIX, and the program is written in C language. Static RAM cell and asynchronous circuit are illustrated as an example.

• Journal of Radiation Protection and Research
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• v.43 no.3
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• pp.114-119
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• 2018

Background: The retrospective dosimetry using RTL quartz can be improved by information for an optical sensitivity of sample connected with the equivalent dose determination. Materials and Methods: The quartz sample from a volcanic rock of Japan was used. After correcting the thermal quenching effect, RTL peaks of quartz were separated by the CGCD method cooperated with the general order kinetics. The number of overlapped glow peaks were ascertained by the $T_m-T_{stop}$ method. The optical sensitivity was examined by comparing the change of intensity on RTL glow peaks measured after exposure to light from a solar simulator with various illumination times. Results and Discussion: Seven glow peaks appeared to be overlapped on the RTL glow curve. The general order kinetics model was appropriate to separate glow peaks. After exposure to light from a solar simulator from a few minutes to 416 hr, the signals for peaks P4 and P5 decayed following the form of $f(t)=a_1e^{-{\lambda}1t}$, while the signals for peaks P6 and P7 decayed by the form of $f(t) = a_1e^{-{\lambda}1t}+a_2e^{-{\lambda}2t}+a_3e^{-{\lambda}3t}$. Conclusion: For dosimetric peaks, the times taken to reduce the RTL signal to half of its initial value were 70 sec for the peak P4, 54 s for the peak P5, 9,840 sec for the peak P6 and 26,580 sec for the peak P7, respectively. We conclude that the optical sensitivity of peaks P4, and P5 gives much higher than that of peaks P6 and P7.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.166-171
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• 2015

This paper shows the design of operational flight program(OFP) using model-based design(MBD) method which is used in various engineering fields to reduce time and flight risks for development. The verification of OFP for DO-178C guidelines carry out by a model advisor function of simulink. The flight control logic on simulink is converted into C-language by auto code generation tool from, then it is implemented on 32bit digital signal processor(DSP). The verifications of flight control algorithm on various weather conditions are performed by the HILS system with Flight simulator program, X-plane.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.170-178
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• 2004

This paper deals with six degree-of-freedom HILS(hardware-in-the-loop-simulation) of KSR-III rocket using a TAFMS(three axis flight motion simulator). This TAFMS HILS test is accomplished before main HILS tests in order to verify the control stability in the presence of TAFMS dynamic effects. The TAFMS HILS test includes initial attitude holding tests for INS initial alignment procedures, timer synchronization tests with an auxiliary lift-off signal, real-time calibration tests using an external thermal recorder, open-loop TAFMS operating tests, and final closed-loop TAFMS HILS tests using the TAFMS attitude measurements as inputs to the closed control loop. The HILS tests are accomplished for several flight conditions composed with nominal flight condition, TWD effect added condition, slosh modes and/or bending modes existing condition, and windy condition, etc.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.393-406
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• 2009

This paper introduces two functions added to the current version of ns-2 simulator for better accuracy of IEEE 802.15.4 network simulations. The first one is to automatically place hidden nodes over the ring topology in which the coordinator is centered, when the number of hidden nodes and total number of nodes is given. Collisions of signals can be distinguished into the trace file according to the ways of participation of hidden nodes. The second one is the CCA deferment algorithm described in IEEE 802.15.4-2006 standard which is not implemented in the current version of ns-2. Owing to these additional functions, we can carry out the precise analysis of the performance effects of hidden nodes and CCA deferment algorithm on 802.15.4 networks. Simulation results present at least 66% of performance degradation in throughput and drastic increase of collision probability up to 90% from 65% by just a single hidden node. Besides, 2006 standard for CCA deferment algorithm gives 19% lower collision probability and 38% higher performance.