• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7B
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• pp.737-743
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• 2002

It is an essential design process to analyze the performance of Synthetic Aperture Radar (SAR) processor before implementation. The contribution of this paper is to identify the chief sources and types of errors, to assess their impact on system performance, and to suggest the analysis technique for principal performance of the space-based SAR processor using Range-Doppler Algorithm (RDA). Also, simulation is performed by the Experimental-SAR (E-SAR) processor to examine the practicability and efficiency of the technique, the results are discussed, and solutions for the problems are recommended. Therefore, this technique can be used to analyze the performance of the space-based SAR processor using RDA.

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.39-45
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• 2017

In this paper, we propose three compensation methods to solve problems in high-resolution airborne infrared camera and to improve long-range target information acquisition performance. First, image motion and temporal noise reduction technique which is caused by atmospheric turbulence. Second, thermal blurring image correction technique by imperfect performance of NUC(Non Uniformity Correction) or raising the internal temperature of the camera. Finally, DRC(Dynamic Range Compression) and flicker removing technique of 14bits HDR(High Dynamic Range) infrared image. Through this study, we designed techniques to improve the acquisition performance of long-range target information of high-resolution airborne infrared camera, and compared and analyzed the performance improvement result with implemented images.

• Korean Journal of Computational Design and Engineering
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• v.22 no.2
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• pp.162-171
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• 2017

Unmanned military vehicles (UMVs) are most commonly characterized as dealing with dull, dirty, and dangerous tasks with automation. Although most of the UMVs are designed to a high degree of autonomy, the human operator will still intervene in the robot's operation, and teleoperate them to achieve his or her mission. Thus, operator capacity, together with robot autonomy and user interface, is one of the most important design factors in the research and development of the UMVs. Further, communication may affect the operator task performance. In this paper, we analyze the operator performance and the communication effects on the operator performance by using the extended Petri nets, called OTSim nets. The OTSim nets was designed by the authors, being extended using pure Petri nets.

• International Journal of Control, Automation, and Systems
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• v.3 no.2
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• pp.217-224
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• 2005

Generally, the underwater flight vehicle (UFV) depth control system operates with the following problems: it is a multi-input multi-output (MIMO) system because the UFV contains both pitch and depth angle variables as well as multiple control planes, it requires robustness because of the possibility that it may encounter uncertainties such as parameter variations and disturbances, it requires a continuous control input because the system that has reduced power consumption and acoustic noise is more practical, and further, it has the speed dependency of controller parameters because the control forces of control planes depend on the operating speed. To solve these problems, an adaptive fuzzy sliding mode controller (AFSMC), which is based on the decomposition method using expert knowledge in the UFV depth control and utilizes a fuzzy basis function expansion (FBFE) and a proportional integral augmented sliding signal, is proposed. To verify the performance of the AFSMC, UFV depth control is performed. Simulation results show that the AFSMC solves all problems experienced in the UFV depth control system online.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.724-726
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• 1998

본 논문에서는 방대한 양의 데이터를 실시간으로 처리하기 위한 병렬 디지털 신호처리시스템을 제안한다. 버스와 메모리의 구조가 다른 네 가지 신호처리부 모델을 제안하고 그들의 성능을 분석한다. 신호처리부의 분석은 소나 알고리즘을 실행하는데 소요되는 하드웨어 지연시간과 버스 지연시간의 합을 척도로 한 성능 분석과 보드의 복잡도를 비교하는 방법을 통하여 이루어졌다. 성능분석한 결과, 지역 메모리와 공유 메모리를 함께 사용하는 모델이 가장 효율적인 것으로 나타났다.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.97-105
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• 2015

A navigation signal based on orthogonal tiered polyphase code was proposed. For the proposed signal, tiered polyphase code was used as the code of a pilot channel. Tiered polyphase code is a complex number type code, and thus the pilot channel and data channel were separated using the Walsh code which makes the correlation between different codes become 0. The results of the simulation indicated that the correlation characteristics and signal acquisition performance of the proposed signal were identical to those of tiered polyphase code, and that the disadvantage of tiered polyphase code could be supplemented through a data channel in terms of signal tracking.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.3
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• pp.231-238
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• 2002

In this paper, we present a new approach to autopilot design for skid-to-turn missiles which may have severe aerodynamic cross-couplings and nonlinearities with angle of attack. The model of missile motion is derived in the maneuver plane and, based on that model, pitch, yaw, and roll autopilot are designed. They are composed of a nonlinear term which compensates for the aerodynamic couplings and nonlinearities and a linear controller driven by the measured outputs of missile accelerations and angular rates. Besides the outputs, further information such as Mach number, dynamic pressure, total angle of attack, and bank angle is required. With the proposed autopilot and simple estimators of bank angle and total angle of attack, it is shown by computer simulations that the induced moments and some aerodynamic nonlinearities are properly compensated and that the performance is superior to that of the conventional ones.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.969-974
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• 2004

For a maneuvering unmanned autonomous helicopter, it is necessary to design a proper controller of each flight mode. In this paper, overall helicopter dynamics is derived and hovering model is linearized and transformed into a state equation form. However, since it is difficult to obtain parameters of stability derivatives in the state equation directly, a linear control model is derived by time-domain parametric system identification method with real flight data of the model helicopter. Then, two different controllers - a linear feedback controller with proportional gains and a robust controller - are designed and their performance is compared. Both proposed controllers show outstanding results by computer simulation. These validated controllers can be used to autonomous flight controller of a real unmanned model helicopter.

• International Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.9-12
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• 2017

In this study, an investigation on mechanical properties of flax natural fiber composite is performed as a precedent study on the design of eco-friendly structure using flax natural fiber composite. The Vacuum Assisted Resin Transfer Molding-Light (VARTML) manufacturing method is adopted for manufacturing the flax fiber composite panel. The VARTML is a manufacturing process that the resin is injected into the dry layered-up fibers enclosed by a rigid mold tool under vacuum. In this work, the resin flow analysis of VARTM manufacturing method is performed. A series of flax composite panels are manufactured, and several kinds of specimens cut out from the panels are tested to obtain mechanical performance data. Based on this, structural design of chemical storage tank for agricultural vehicle was performed using flax/vinyl ester. After structural design and analysis, the resin flow analysis of VARTM manufacturing method was performed.

• Journal of Plant Biotechnology
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• v.44 no.1
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• pp.1-11
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• 2017

Evolutionary studies conducted on NAC (NAM, ATAF1&2, and CUC2) genes for all major groups of land plants, indicate the presence of the NAC subfamilies, even in the early land plants. The varied roles played by NAC proteins in plant growth and development range from the formation of shoot apical meristem, floral organ development, reproduction, lateral shoot development, and defense responses to biotic and abiotic stresses. Considering the value and importance of solanaceous crops, the study of NAC proteins in these plants needs to be intensified. This will help to identify and functionally characterize their promoters, which will subsequently aid in engineering plants with improved performance under stressful conditions. In this review, the functionally characterized NAC transcription factors specific to tomato, potato, tobacco, chili pepper and eggplant (aubergine) are summarized, clearly indicating their biological functions in the defense mechanism of the plants, against biotic and abiotic stresses.