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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 4, Issue 2 - Dec 2000
Volume 4, Issue 1 - Jun 2000
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Receiver Front-End of Radar for the Coherent Operation
Lee, Taek-Kyung ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 1~10
When the magnetron is employed as a radar transmitter source, the receiver needs to detect the frequency and the phase of the transmitting signal for the coherent operation. The local oscillator frequency is tuned for the stable intermediate frequency and the coherent oscillator generates the stable signal which is phase-locked to the transmitting signal. In this paper, we designed and implemented the receiver front-end including AFC(Automatic Frequency Control) circuit, STALO(Stable Local Oscillator) and COHO (Coherent Oscillator) unit.
Implementation and Evaluation of Flight Tasks in Instrument Flight Simulator
Hwang, Soo-Chan ; Baek, Joong-Hwan ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 11~22
Instrument flight simulators are used for training the interpretation and operation techniques for all kinds of aircraft instruments, cockpit procedures, etc., in order that pilots cope with the situations which can be occurred in actual flight. However, the simulators developed so far are concerned about operating in same environment to actual aircraft. And little researches concentrate on developing systematic training system for basic tasks and takeoff-landing procedures, and automatic evaluation methods on the training results. Therefore, in this paper, we propose implementation and evaluation methods for flight tasks such as tasks in flight, takeoff-landing procedures and course flight.
Stacked Microstrip Antenna Design for PCS Base Station
Park, Jong-Sung ; Jeon, Joo-Seong ; Kim, Hyung-Bum ; Kim, Dong-Won ; Jin, Sung-Woo ; Lee, Jin ; Lee, Yun-Hyun ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 23~35
In this paper, the design for a PCS base station antenna which is using broadband method by a stacked structure has been studied. The sensitive parameters, such as the parasitic elements, the height of air layer between the upper and lower patch, and the variation of feed point, of the microstrip antenna that has stacked structure in a characteristics variation situation are classified and the characteristics has been investigated through the simulations. A designed antenna has following characters. Impedance bandwidth is Z57.5MHz(VSWR
2), horizontal beamwidth is
, and gain is 14.7dBi. Therefore, it is confirmed the characteristics is good. In this paper, through the designing of a stacked microstrip antenna, we has investigated the availability for Korea PCS base station antenna.
Frequency-Shifting Digital Demodulator by Bandpass Sampling
Moon, Sung-Bin ; Kim, Sae-Yeon ; Jung, Shin-Chul ; Lee, Byung-Sub ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 36~44
A frequency-shifting technique that uses a digital filter in order to interpolate a bandpass-sampled signal at a low-pass position is investigated. The discussion focuses on the derivation of the required digital filter. It is shown that second-order bandpass sampling offers more flexibility than first-order bandpass sampling in the sense of sampling frequency choice. It is also shown that the well-known quadrature-sampling method for frequency-shifting is a special case of the general second-order sampling technique. The advantages of the mixer-free digital quadrature demodulations are increased flexibility for sampling frequency choice and high precision for I/Q component extraction, and this type of modulation can be applied for modern radar signal processing with high performance.
Fixed Point Algorithm for GPS Measurement Solution
Lim, Samsung ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 45~49
A GPS measurement solution, in general, is obtained as a least squares solution since the measurement includes errors such as clock errors, ionospheric and tropospheric delays, multipath effect etc. Because of the nonlinearity of the measurement equation, we utilize the nonlinear Newton algorithm to obtain a least squares solution, or mostly, use its linearized algorithm which is more convenient and effective. In this study we developed a fixed point algorithm and proved its availability to replace the nonlinear Newton algorithm and the linearized algorithm. A nonlinear Newton algorithm and a linearized algorithm have the advantage of fast convergence, while their initial values have to be near the unknown solution. On the contrary, the fixed point algorithm provides more reliable but slower convergence even if the initial values are quite far from the solution. Therefore, two types of algorithms may be combined to achieve better performance.
Performance Analysis of the Tracking Filter Employing Jerk Model for Highly Maneuvering Targets
Joo, Jae-Seok ; Lim, Sang-Seok ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 50~66
For a long time target maneuvers in tracking problem have been a difficult task to handle. Once a maneuvering such as abrupt change in target accelerations occur, the tracking fiter no longer yields a reasonable estimate of the target position. In order to resolve this cumbersome maneuvering problem. Advanced methods have here proposed : Colored noise, IE(Input Estimation), VD(Variable Dimension), IMM(Interaction Multiple Model), Jump-type processes and jerk model, etc. In this paper, tracking performance of the jerk model is analyzed. Jerk model in which the derivative of target acceleration is included as a state recently attracted considerable attraction. Firstly 3-dimensional Kalman filter is described on the basis of jerk model. Then using this filter, Monte-Carlo simulations are carried out and the filter formance with respect to the variation of jerk time-constant is analyzed. Especially, since jerk model's transient performance is expected to be poor, the performance of analysis of transient response of the model is included too.
Reduced Search for a CELP Adaptive Codebook
Lee, Ji-Woong ; Na, Hoon ; Jeong, Dae-Gwon ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 67~77
This paper proposes a reduction scheme for codebook search time in the adaptive codebook using wavelet transformed coefficients. In a CELP coder, pitch estimation with a combined open loop and closed loop search in adaptive codebook needs a lengthy search. More precisely, the pitch search using autocorrelation function over all possible ranges has been shown inefficient compared to the consuming time. In this paper, we propose a new adaptive codebook search algorithm which ensures the same position for the pitch with maximum wavelet coefficient over various scaling factors in Dyadic wavelet transform. A new adaptive codebook search algorithm reduces 25% conventional search time with almost the same quality of speech.
The Impact of Aviation Safety on the Consumer's Choice of Airline in the Air Transport Market of Korea
Lee, Kang-Seok ; Lee, Soong-Chang ;
The Journal of Advanced Navigation Technology, volume 4, issue 1, 2000, Pages 78~92
This study will be regarded significant in terms that empirical analysis was used to prove "Aviation Safety", a variable which had not been regarded as a airline choice factor within Korea air transport market so far, has an effect on the aviation consumers' airline preference change and choice after recent frequent aviation accidents. On releasing this paper. I wish, it can be another opportunity for Korean two national flag airlines to reappraise and reinforce the significance of "aviation safety" and set forth immediate vigorous efforts to support the government's aviation safety improvement countermeasures The study was performed to provide data and information for this.