• 한국과학교육학회지
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• 제41권5호
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• pp.415-428
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• 2021

COVID-19로 인하여 도입된 원격 과학 수업은 이제 교사들에게 새로운 일상으로 받아들여진다. 이러한 상황에서 교사가 지난해의 실행을 습관적으로 되풀이하기보다는 변화하는 맥락을 적극적으로 해석하고, 맥락에 적절한 학습 환경을 조성하는 것이 요구된다. 본 연구에서는 COVID-19로 인하여 시행된 원격 수업 2년 차 상황에서 교사가 문제를 인식하고, 이를 해결하는 실행에서 드러나는 교사 행위주체성과 이때의 맥락을 분석하였다. 특히, 2020년 4월에서부터 2021년 7월까지 16개월 동안 교사의 원격 과학 수업 실행을 추적하여 맥락에 따라 변화하는 교사의 행위주체성을 탐색하였다. 이를 위하여 중등학교 과학교사 3인을 대상으로 질적 사례 연구를 진행하였다. 연구 참여자와의 인터뷰, 연구 참여자가 사용한 교육자료를 수집하고, 이를 지속해서 검토하며 분석하였다. 연구 결과, 교사는 스스로 자신의 수업을 비판적으로 성찰함으로써 자신의 원격 과학 수업 실행에서의 문제를 인식하고 이를 해결하기 위한 행위주체성을 발현하거나 외부로부터의 변화에 능동적으로 적응하기 위하여 행위주체성을 발현하거나 자신이 추구하는 과학 교육을 원격 수업 상황에서도 구현하기 위하여 행위주체성을 발현하였다. 그리고 이 과정에서 지난해 원격 과학 수업을 실행한 경험 및 이로부터 축적된 실천적 지식, 자신의 실행에 대한 성찰, 원격 과학 수업에 대한 장·단기적 목표가 영향을 미쳤다. 또한, 교사가 속한 맥락에서 원격 수업의 질 제고를 추구하는 학교 공동체의 분위기나 교사 사이의 활발한 소통과 협력 역시 교사 행위주체성 발현을 촉진하였다. 본 연구는 우리나라 원격 과학 수업 상황에서 어떠한 과학교사 행위주체성이 발현되었는지 탐색하였으며, 이 과정에서 영향을 미친 맥락을 분석하였다. 또한, 같은 교사가 상황이 변화함에 따라 행위 주체성 발현에 어떠한 변화가 나타나는지, 그리고 그 과정에 영향을 미치는 맥락을 이해하기 위하여 교사의 개인적인 요인 및 맥락적 요인을 분석하였다. 이를 통하여 교사 행위주체성 발현을 지원할 수 있는 전략을 마련하는 데 시사점을 제시하고자 한다.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.126-131
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• 2014

This paper is concerned with a track management method for a naval combat system which receives the tracks information from multi-sensors and multi-tactical datalinks. Since the track management of processing the track information from diverse sources can be formulated as a data fusion problem, this paper will deal with the data fusion architecture, track association and track information determination algorithm for the track management of naval combat systems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1822-1825
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• 2003

A practical range estimator based on the robust Kalman filter is proposed to solve the range estimation problem for surface to air missile(SAM) homing guidance. Apart from the previous works based on the extended Kalman filter(EKF) with bearing only measurement, the proposed scheme makes use of line-of-sight(LOS) rate to ensure the fast convergency at long-range. In this reason, the robust Kalman filter is considered to deal with LOS rate measurement error. The recursive linear structure of proposed filter is easy to implement and make it possible to reduce computational burdens. Moreover, it shows good estimation performance without specific guidance law such as oscillation proportional navigation guidance(OPNG).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2230-2233
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• 1997

In this paper, the study on noise-seperator, which can seperate the modes of conducted noise, was conducted. The principle and analysis procedure of noise-seperator were studied. We presented the experiment, in which the noise problem was easily solved by seperating the modes from generated conducted noise of equipment using the fabricated noise-seperator.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.474-477
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• 2005

In tactical theater, it is crucial to detect ground moving targets and to locate them precisely. This problem can be resolved by using SAR (Synthetic Aperture Radar) sensors providing GMTI (Ground Moving Target Indication) capability. In general, to implement a robust GMTI sensor is not simple because of the strong competitions between target signals and clutter signals on the ground, and low speed of moving targets. Contrary to the case that a delay canceller is mostly suitable for ground surveillance radars, DPCA (Displaced Phase Centered Antenna) or STAP (Space Time Adaptive Processing) techniques have been adapted for GMT! function of modem airborne radars. In this paper, anew scheme of DPCA using two passive antennas with vertical separation is proposed, which also provides good clutter cancellation performance. The proposed scheme enables us to scan straight ahead of the carrying platform that is impossible with typical DPCA configuration. Simulations using various conditions have been performed to validate the proposed scheme, and the results are acceptable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.658_659
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• 2009

This paper deals with the numerical implementation of the material sensitivity analysis, which is used to efficiently determine an optimal electric current distribution on a ship hull by corrosion of ship. A material sensitivity formula for the forward problem formulated in terms of the equivalent current method is analytically derived. Then, the components of the adjoint system including the electric pseudo-source are thoroughly investigated in order to obtain the first-order gradient information of an objective function with respect to the electric current. The purposed method has been successfully applied to a model ship and the predicted result on the underwater electric field due to corrosion of ship have been compared to that computed by FNREMUS software.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.757-766
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• 2017

For implementing the proportional navigation guidance law on passive homing missiles equipped with strapdown imaging infrared seekers, the line-of-sight angles and rates with respect to the inertial frame should be estimated by carefully handling the parasitic instability effect due to the seeker's latency. By introducing a new state vector representation along with the Pade approximation for compensating the time-delay of the seeker, this paper proposes a new guidance filter structure, stochastic dynamic models and measurement equations, in three-dimensional homing problem. Then, it derives the line-of-sight angle and rate estimator in general two-dimensional engagement by applying the extended Kalman filter to the proposed structure. The estimation performance and the characteristics of the proposed filter were evaluated via a series of numerical experiments.

• The Journal of the Acoustical Society of Korea
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• 제24권1E호
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• pp.34-37
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• 2005

Ryu et al. proposed a multiple target angle-tracking algorithm without a data association problem using angular innovations. This algorithm, however, needs the computational loads in proportion to the square number of sensors regardless of the number of targets, because it uses a nonlinear equation between the signal subspace and angular innovation. In this Paper, we proposed an efficient algorithm for the multiple target angle-tracking using angular innovations. The proposed algorithm extracts the angular innovations from noise subspace. Also, it is demonstrated by computer simulations dealing with the tracking of crossing targets. The simulation results show that the computational loads of the proposed algorithm are $80\%$ and $60\%$ of those of Ryu's algorithm for 3 targets and 6 targets without degrading the performance of the target tracking.

• 한국군사과학기술학회지
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• 제18권6호
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• pp.816-821
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• 2015

In this paper, an in-flight prediction method of thrust profiles for solid rocket motors is proposed. Actually, it is very difficult to have detailed information about the performance of the rocket motors beforehand because it is quite sensitive to combustion environments. To overcome this problem, we have developed an algorithm for generating in-flight prediction of rocket motor performance in realistic environments via a reference burnback profile and accelerations measured at a short time-interval just after launch. The performance is evaluated through a lot of flight test results.

• Journal of Positioning, Navigation, and Timing
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• 제3권2호
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• pp.37-44
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• 2014

The most effective method to overcome GPS jamming problem is to use an adaptive array antenna which has the capability of beamforming or nulling to a certain direction. In this paper, Space Time Adaptive Processing (STAP) beamforming algorithm of four elements array antenna will be designed and the anti-jamming performance will be analyzed. According to the analysis, the signal to noise ratio (SNR) and anti-jamming performance can be enhanced by beamforming algorithm. Also, the time tap effect of STAP algorithm will be analyzed theoretically and verified with array antenna modeling and simulation. Specially, the cautious selection of reference time tap in STAP can prevent the degradation of position accuracy performance.