이대우D . W . Lee,조경래K . R . Cho

DOI: JANT Vol.4(No.2) 103-113, 2000

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There are several methods in the mathematical modeling of a satellite with flexible appendages. In this paper, the hybrid Lagrange`s equations of motion using assumed modes method are derived. The assumed modes method is one of approximate methods which have shorter calculation time due to low-dimension compare with FEM. These consist of three-equations about angular velocities and two-equations about flexible deformations, and physically represent interaction between hub and solar panel. In an attitude control, a control law is designed to minimize a given performance index considering not only control input but also vibration suppression. For these purpose, this paper applies LQG and LQG/LTR schemes to this model and finally show the capability for attitude control including vibration suppression. Especially, this paper shows the method of assumption as nonsingular system through singular value division for LQF/LTR design.

김봉균Bong Gyun Kim,유광의Kwang Eui Yoo

DOI: JANT Vol.4(No.2) 114-131, 2000

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An airline should consider the number of seats or size of aircraft, when it composes fleet or selects a type of aircraft for some routes. There are two major factors considered for this choice problem under the assumption that the objectives of an airline is a profit maximization: the operating cost and revenue from the aircraft operated. This research tries to solve the problem of aircraft size selection by airline. The study applies four steps to get optimal choice of aircraft size: (1) cost analysis for the relationship between airline operation cost and aircraft size: (2) market share and revenue analysis: (3) flight segment-level analysis, based on the derived cost, demand and revenue functions: and (4) network-level analysis to see how airlines make choice of aircraft size systematically at a network level. An airline can accommodate the increasing air travel demand by either increasing operation frequency, or increasing aircraft size that is represented by seat capacity, or both. Airport runway capacity and productivity depend on the size of aircraft used at airport. This paper presents the understanding of how airlines make decisions on the size of aircraft to operate, how they will adjust their choices when airport capacity is constrained, and how public regulation such as policy for landing fees could influence airlines` aircraft choice.

홍영선Young Sun Hong,권태환Tae Hwan Kwon,권용수Yong Soo Kwon

DOI: JANT Vol.4(No.2) 132-142, 2000

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This paper includes a study on the performance analysis of SDINS by a simulator using Matlab/Simulink. The performance model is considered gravity and Coriolis force, and a barometer is included to damp down diversity of a perpendicular axis error. Using the simulator, the performance included gyro sensor errors was analyzed in various maneuvering patterns. Also, the performance is virtually presented for the variation of error parameters of gyro and accelerometer under GUI.

오세갑Se Kab Oh,강희조Heau Joh Kang,최용석Yong Surk Choi,조성준Sung Joon Cho

DOI: JANT Vol.4(No.2) 143-151, 2000

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In this paper, short range IVC (Inter-Vehicle Communication) channel is modeled in three kinds considering rain attenuation and oxygen absorption. And the performance of DS/CDMA communication system in one path Rician model suitable for platton driving which is the final goal of AVHS(Advanced Vehicle & Highway System) is analyzed. Also, the reflection coefficients in 60 GHz is calculated. For the performance improvement both BCH channel coding and MRC diversity reception technique are adopted. The BER performance is evaluated as a function of packet length. Rician depth and the distance between vehicles.

문진섭Jin Seob Moon,정수영Soo Young Jung,이택경Taek Kyung Lee

DOI: JANT Vol.4(No.2) 152-161, 2000

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Recently, it is considered to combine the GPS receiver with the GLONASS for the improvement of performance and accuracy. This combined system reduces errors by SA for GPS, and has merits to select receivable satellite. In this paper, aperture-coupled patch antenna and small sized ceramic dielectric patch antenna are designed and implemented for GPS/GLONASS combined receiver, which show a wideband characteristics with circular polarization. The manufactured antennas have the bandwidth more than 240 MHz, VSWR less than 1.5:1, and the axial ration less than 3㏈, and satisfy required characteristics of the GPS/GLONASS antenna.

주재석Jae Seok Joo,박제홍Je Hong Park,임상석Sang Seok Lim

DOI: JANT Vol.4(No.2) 162-170, 2000

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Maneuvering targets are difficult for the Kalman filter to track since the target model of tracking filter might not fit the real target trajectory and the statistical characteristics of the target maneuver are unknown in advance. In order to track such a wildly maneuvering target, several schemes had been proposed and improved the tracking performance in some extent. In this paper a Kalman filter-based scheme is proposed for maneuvering target tracking. The proposed scheme estimates the target acceleration input vector directly from the feature of maneuvering target trajectories and updates the simple Kalman tracker by use of the acceleration estimates. Simulation results for various target profiles are analyzed for a comparison of the performances of our proposed scheme with that of conventional trackers.

홍승범Sung Bum Hong,이정구Jung Gu Lee,나원Won Na,최은석Un Seok Choi,황병원Byung Won Hwang,백중환Joong Hwan Baek

DOI: JANT Vol.4(No.2) 171-181, 2000

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In this paper, we propose an AVLS(Automatic Vehicle Location System) using the DSRC(Dedicated Short Range Communication) which adopts a radio communication tool between RSE(Road-Side Equipment) and OBE(On-Board Equipment) on a vehicle and uses the ISM bandwidth of 5.8GHz radio frequency. Typical AVLS uses the sensors for detecting the vehicle, but the DSRC system is developed for supporting various services such as the position of vehicle, clearance, vehicle to vehicle communication, collection and distributions of traffic and road information. Also, for fast processing, we design three-layer configuration of physical(L1), data link(L2), and application layer (L7), which simplifies the seven-layer configuration, We suggest the proposed system as a new technology for replacement of typical wireless communication system and sensors for AVLS.

강영흥Young Heung Kang,문승영Seung Young Mun

DOI: JANT Vol.4(No.2) 182-190, 2000

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In this paper, interference effects between NGSO and HAPS in the feeder link have been simulated and analyzed by means of calculating excess time percent and duration below the C/I protection ratio. As the results, in the case of HAPS interference into NGSO. it can be obtained that the lowest C/I values are 20.42㏈ in 50km and 12.73㏈ in 20km of HAPS altitudes, respectively. And in the case of NGSO interference into HAPS, it can be obtained that the lowest C/I values are 13.94㏈and 10.42㏈ respectively. HAPS system has more interference reception from other systems or effects more interference into other systems as its altitude is lower. Also, the lowest C/I values are appeared at difference time with its altitude.

김원규Won Kyu Kim

DOI: JANT Vol.4(No.2) 191-200, 2000

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Recently, NORAD reported that only 6% of the total space objects cataloged in the table as above 10cm objects were being operated for the space missions and the others were just non-operated objects, such as rocket body, useless satellites which were finished their missions, and other fragments of space debris. A major contributor to the orbital debris background has been object breakup. Breakups generally are caused by explosions and collisions. Several international research groups and big countries` governments are trying to develop advanced technology for de-orbiting and to design new future satellites` modeling. The future need to be considered continuously that kind of technology and designing to preserve space and global environmental safety and to maintain welfare of mankind forever.