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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Advanced Navigation Technology
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Journal DOI :
The Korea Navigation Institute
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Volume & Issues
Volume 7, Issue 2 - Dec 2003
Volume 7, Issue 1 - Jun 2003
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A Study on Microstrip Log-Periodic Antenna for Receiving the Direct Broadcasting Satellite(DBS) Signal
Jang, Won-Ho ; Jin, Jae-Sun ; Lee, Yun-Hyun ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 101~107
In this study, we provide a single element log-periodic antenna that the feeding networks and array structures are aperture coupled and series dipole array type. We made the antenna for direct receiving the Moogoongwha satellite broadcasting signal. The transmission power was able to feed the patch dipole in series due to lay perpendicularly 8 series patch dipole on tapered slot. The patch dipole radiation pattern which fed in series power, make the main beam direction up
within the BS/CS bandwidth. The main beam gain was measured 9.31~11.03 dBi. Using 32 elements to array the elements properly, we acquire
array structure on limited PCB board. As a result, it has been found that the new planar DBS antenna structure have high gain over 10dBi and acceptable elevation angle over 42 degree, and we can apply this result to commercial DBS reception antenna manufacturing.
Development of Two Types of Radar Vehicle Detectors
Kim, Ihn Seok ; Kim, Ki Nam ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 108~117
In this paper, two types of radar vehicle detectors compatible with currently being used ILD(Inductive Loop Detector) without any modification has been developed. With these vehicle detectors based on FMCW altimeter and Doppler speedometer techniques at 24 GHz, the length and speed of a vehicle can be detected. For signal processing part, we have used DAQ board and programmed with LabView. For compatibility with traffic information network connected with existing ILD's, traffic information has been sent to VDS by using RS-232C standard interface. This development has improved approximately 10% in accuracy in terms of the speed and length information compared with that of the installed ILD in the test field.
A Study on the methodology of Estimation National Spectrum Requirements and Network Resources depending on traffic model variation in future mobile communications service
Chung, Woo-Ghee ; Hong, Een-Kee ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 118~127
ITU-R recommends general methodology to provide current and future mobile communication services and 12 parameters to calculate terrestrial spectrum requirements. In this paper we analyzed 12 parameters suggested by ITU-R Recommendation and provided a method to determine a specific parameter value in a specific region. We calculated spectrum requirements and network resources for year 2010 in Korean mobile environment by applying parameter values acquired in parameter analysis method of this paper. And we analyzed the variation of spectrum requirements by calculating spectrum requirements depending on variation of parameters for future mobile communication services.
Compensation of Distorted WDM signals due to Cross Phase Modulation Effects using Mid-Span Spectral Inversion
Lee, Seong-Real ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 128~134
In this paper, we investigated the degree of compensation for WDM channel signal distortion due to chromatic dispersion, self phase modulation (SPM) and cross phase modulation (XPM) as a function of transmission length using mid-span spectral inversion (MSSI) compensation method. The considered system is
Gbps intensity modulation direct detection (IM/DD) WDM transmission system. This system has highly nonlinear dispersion shifted fiber (HNL-DSF) as a nonlinear medium in optical phase conjugator (OPC). We confirmed that the transmission length is more increased by applying MSSI to distorted signal due to chromatic dispersion, SPM and XPM as dispersion coefficient of fiber becomes higher. And the compensation degree of distorted WDM channels due to chromatic dispersion, SPM and XPM becomes better stable as dispersion coefficient of fiber becomes higher.
A Study on the Estimation of Lift/Drag Using the Flight Data
Hong, Gyo-Young ; Shin, Seong-Sik ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 135~141
During flight the analysis of aircraft data recorded has played an important role in determining the causes of accidents. However, using the QAR, recently some airlines have begun to analyze flight data from uneventful airline flights to identify potential problems and correct them before they lead to accident. This paper, after the flight using the recorded data in QAR, proposes an estimated method which determines CL/CD values. The generalized aircraft dynamic equations were expressed as an estimated equation, which verified the effectiveness with simulation. The results of the present method showed that the understand of variation values of CL/CD is of great use for performance enhancement.
Comparative Study of the Symbol Rate Detection of Unknown Digital Communication Signals
Joo, Se-Joon ; Hong, Een-Kee ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 141~148
This paper presents and compares several techniques that detect the symbol rate of unknown received signal. Symbol rate is detected from the power spectral density of the circuits such as the delay and multiplier circuit, the square law circuit, and analytic signal, etc. As a result of discrete Fourier transform of the output signals of these circuits, a lot of spectral lines and some peaks appear in frequency domain and the position of first peak is corresponding to the symbol rate. If a spectral line on the frequency that is not located in symbol rate is larger than the first peak, the symbol rate is erroneously detected. Thus, the ratio between the value of first peak and the highest side spectral line is used for the measure of the performance of symbol rate detector. For the MPSK modulation, the analytic signal method shows better performance than the delay and multiplier and square law circuits when the received signal power is lager than -20dB. It is also noted that the delay and multiplier circuit is not able to detect the symbol rate for the QAM modulation.
A Study of an Association Admission Method for Public Wireless LAN Systems
Lee, Hyun-Woo ; Yoon, Hong ; Yoon, Chong-Ho ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 149~155
This paper generally relates to the field of wireless local area networks(WLANs), and more particularly, to AP selection and association methods for the performance of a station. In these days, IEEE 802.11 Wireless LAN network is widely deployed and used as an emerging service to connect high-speed Internet in the public wireless environment. But, if there are many users in hot spot area, they suffer a severe decrease of performance. Thus it needs an association and access control mechanism especially when it is used in the public environment. In this paper, we suggest a selection and association method using Beacon or Probe Response frames based IEEE 802.11. Station selects AP using the information of the capacity area in a Beacon or a Probe Response frame. According to the present paper, an association method for a public WLAN service, which includes a WLAN user terminal and an AP for relaying WLAN communications to and from the user terminal, includes the steps of the user terminal asking the AP's states for access to a radio channel; and the station selects and associates with the AP. According to the above-described selection in a high speed wireless Internet service based on public WLAN technologies that are currently in operations. Further, it is possible to improve the efficiency of network management.
Error Correction of a Low-Cost Hybrid Navigation System
Lim, Samsung ; Cho, Sung Jun ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 156~161
In this study, a hybrid navigation system with a low-cost GPS Receiver plus Gyro and Odometer is developed and tested. This hybrid navigation system adopted a modified coupling method which can be distinguished from tightly coupled method or loosely coupled method, so that GPS receivers or Gyros or Odometers can be chosen arbitrary. Comparing to the existing hybrid navigation system, the test results show that this navigation system enhances the accuracy and is robust against the multipath error. It is also proven that this system has an advantage of acquiring GIS data for post processing.
Robust Control of Robot Manipulators using Vision Systems
Lee, Young-Chan ; Jie, Min-Seok ; Lee, Kang-Woong ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 162~170
In this paper, we propose a robust controller for trajectory control of n-link robot manipulators using feature based on visual feedback. In order to reduce tracking error of the robot manipulator due to parametric uncertainties, integral action is included in the dynamic control part of the inner control loop. The desired trajectory for tracking is generated from feature extraction by the camera mounted on the end effector. The stability of the robust state feedback control system is shown by the Lyapunov method. Simulation and experimental results on a 5-link robot manipulator with two degree of freedom show that the proposed method has good tracking performance.
A Study on the Fault Tolerant Control System for Aircraft Sensor and Actuator Failures via Neural Networks
Song, Yong Kyu ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 171~179
In this paper a neural network-based fault tolerant control system for aircraft sensor and actuator failures is considered. By exploiting flight dynamic relations a set of neural networks is constructed to detect sensor failure and give alternative signal for the faulty sensor. For actuator failures another set of neural networks is designed to perform fault detection, identification, and accomodation which returns the aircraft to a new stable trim. Integrated system is simulated to show the performance of the system with sensor and control surface failures.
Analysis of Coplanar Waveguide Discontinuities Using Accurate Closed-Form Green's function
Kang, Yeon-Duk ; Song, Sung-Chan ; Lee, Taek-Kyung ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 180~190
By using accurate closed-form Green's functions obtained from real-axis integration method, the full-wave analysis of CPW discontinuities are performed in space domain. In solving MPIE(Mixed Potential Integral Equation), Galerkin's scheme is employed with the linear basis functions on the triangular elements in air-dielectric boundary. In the singular integral arising when the observation point and source point coincides, the surface integral is transformed into the line integral and the integral is evaluated by regular integration. By using the Green's function from the real-axis integration method, the discontinuities are characterized accurately.
Comparative Performance Analysis of Transmit Diversity Technique for WCDMA Systems
Lee, Sang-Ho ; Kim, Young-Sun ; Park, Hyung-Rae ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 191~198
In this paper, we analyze the performance of transmit diversity techniques which are the key technologies of the third generation mobile communication systems. Transmit diversity techniques adopted on the specification of 3GPP are classified into open-loop and closed-loop methods depending on the existence of feedback data. In WCDMA systems, the DPCH signal is space-time coded to provide a mobile station with diversity. Computer simulations shall be performed to analyze and compare their performance considering the effect of mobile speed, number of path, power control, and delay of feedback with the WCDMA slot format #13 for application to WCDMA systems.
Adaptive CSMA/CA Protocol Using Flag in Aeronautical VHF Communication
Kim, Yong Joong ; Park, Yong Tae ; Park, Hyo Dal ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 199~205
In this paper, CSMA/CA protocol is modified for aeronautical VHF communication through collision alleviation and the change of retransmission slot selection method in flag used transmission. When collision occurred in the contention period of CSMA/CA process, it is generally waiting for retransmission delay and it has the double size of CW(Contention Window). To solve this problem, this paper modifies the change procedure of original contention window size and reduces the state transition in collision among the whole of it. Also, in this paper we reduces the second collision probability through the station has to enter Backoff mode with increased contention window in the first collision. In the result of simulation, it is verified that it has good property in throughput and delay, So the proposed protocol is suitable for aeronautical VHF communication.
P&R Porting & Test-chip implementation Using Standard Cell Libraries
Lim, Ho-Min ; Kim, Nam-Sub ; Kim, Jin-Sang ; Cho, Won-Kyung ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 206~210
In this paper, we design standard cell libraries using the 0.18um deep submircom CMOS process, and port them into a P&R (Placement and Routing) CAD tool. A simple test chip has been designed in order to verify the functionalities of the 0.18um standard cell libraries whose technical process was provided by Anam semiconductor. Through these experiments, we have found that the new 0.18um CMOS process can be successfully applied to automatic digital system design.
Characteristics of Ta-Ti Gate Electrode for NMOS Device
Kang, Young-Sub ; Seo, Hyun-Sang ; Noh, Young-Gin ; Lee, Chung-Keun ; Hong, Shin-Nam ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 211~216
In this paper, characteristics of Ta-Ti alloy was studied as a gate electrode for NMOS devices to replace the widely used polysilicon. Ta-Ti alloy was deposited directly on
by a co-sputtering method using two of Ta and Ti targets. The sputtering power of each metal target was 100W. To compare with Ta-Ti, Ta deposited with a 100W sputtering power was fabricated as well. In order to investigate the thermal/chemical stability of the Ta-Ti alloy gate, the alloy was annealed at
with rapid thermal annealer. No appreciable degradation of the device was observed. Also the results of electrical analysis showed that the work function of Ta-Ti metal alloy was about 4.1eV which was suitable for NMOS devices and sheet resistance of alloy was lower than that of polysilicon.
Performance Analysis of the Tracking Filter for a Maneuvering Target of Poisson-Type Subject To System Modeling Error
Oh, Sang-Byung ; Kim, Sang-Jin ; Lim, Sang-Seok ;
The Journal of Advanced Navigation Technology, volume 7, issue 2, 2003, Pages 217~226
Recently Lim has proposed a linear, recursive, unbiased minimum variance filter for a maneuvering target based on the maneuver dynamics modeled as a jump process of Poisson-type. In the proposed filter it was assumed that the state transition parameters of the jump used for target maneuver modeling are a priori known to the filter. However, in most cases they are not known in practice. In this paper, we consider the influence of system (target) modeling error on the performance of the proposed tracking filter arising from the maneuver tracking. For qualitative analysis Monte-Carlo simulations are carried out against employing the maneuver model with different state transition parameters from the actual values.