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금정훈,나성웅 한국우주과학회 2009 Journal of Astronomy and Space Sciences Vol.26 No.4
탑재체(Payload)는 수동형과 능동형으로 분류되며, 다양한 형태의 레이더 영상(Radar Image)을 획득하기 위한 위성은 일반적으로 능동형 탑재체인 SAR(Synthetic Aperture Radar)를 이용한다. SAR 위성은 탑재체에서 송신한 전파가 반사되는 것을 획득하여 영상을 형성한다. 때문에 위성이 반사신호를 설계한대로 획득하여 영상을 구성하기 위해서는 궤도에서 실제로 획득한 지상 영상을 기반으로 검보정을 수행하여야 한다. 이에 필요한 것이 지상 목표물인 각면판 반사기(CR; Corner Reflector)이다. 반사기(Reflector)는 다양한 형태가 있으며, SAR를 탑재한 위성의 특성 및 운영목적에 적절하게 설계되어 활용된다. 여기서는 최적의 반사기와 효율적인 반사기들의 특성을 확인하고 그에 대한 고찰을 수행하였다. 또한 그 결과를 바탕으로 삼면판 반사기(Trihedral Corner Reflecotr)를 설계하고 관련 성능을 확인하였다. The payload can be classified as a passive and active type. Generally radar satellite to acquire specific information through various radar images will use the SAR (Synthetic Aperture Radar) as active type payload. the principal of SAR satellite is to receive the signal returned from certain objects and/or surfaces in order to construct an radar image. The data acquired from the satellite in its real orbit shall be needed to perform successful CAL/VAL (Calibration & Validation) because the SAR satellite have to receive the returned signal for SAR image construction. In order to do the above, the returned signal shall be related to ground targets. Especially ground target is the corner reflector (CR) for CAL/VAL. Generally the reflector has various types and shapes. Their selection can be dependent on characteristics and mission objectives of SAR satellite. In this paper, reflector focused on the optimal case and effective case has been studied and then the trihedral corner reflector under this study has been designed and its performance also analyzed.
금정훈,나성운 한국우주과학회 2009 Journal of Astronomy and Space Sciences Vol.26 No.4
Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.
금정훈,한다솔,안성일,이성의,Kum, Jeong-Hun,Han, Da-Sol,Ahn, Sung-Il,Lee, Seong-Eui 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.9
In this study, the opto-electric properties of EL devices with PMN dielectric layer with variation of firing tempereature were investigated. For the PMN dielectric layer process, the paste was prepared by optimization of quantitative mixing of PMN powder, $BaTiO_3$, Glass Frit, $\alpha$-Terpineol and ethyl cellulose. The EL device stack consists of Alumina substrate ($Al_2O_3$), metallic electrode (Au), insulating layer (manufactured PMN paste), phosphor layer (ELPP- 030, ELK) and transparent electrode (ITO), which is well structure as a thick film EL device. The phase transformation properties of PMN dielectric with various firing temperatures of $150^{\circ}C$ to $850^{\circ}C$ was characterized by XRD. Also the opto-electric properties of EL devices with different firing temperature were investigated by LCR meter and spectrometer. We found the best opto-electric property was obtained at the condition of $550^{\circ}C$ firing which is 3432.96 $cd/m^2$ at 1948.3 pF Capacitance, 40 kHz Frequency, 40% Duty, Vth+330 V voltage.
효율관리대상품목의 에너지소비효율기준 관리의 선진화 방안에 대한 연구
金正勳,黃盛郁 弘益大學校 科學技術硏究所 2005 科學技術硏究論文集 Vol.16 No.-
Nowadays the concern about development and strategies of high-efficient equipments is getting higher globally as Kyoto Protocol has taken effect this year and oil has been rising in price tremendously. Developed countries have already commenced the study and research for this problem and are looking for various solutions. In this paper, situation of managements of energy efficiency standards in foreign countries and Korea is investigated and analyzed. Each country has various laws, strategies, and standards associated with energy efficiency. So the environment and own situation of each country are reflected in the contents and criteria. This paper show how the direction of energy efficiency standards and the management would be developed desirably in the future and why national standards should be gradually internationalized and be prepared for global competency.
학습곡선 및 확산모형을 이용한 TV의 에너지효율기준 시행에 의한 에너지 절감량 추정 방안 연구
金正勳,黃盛郁 홍익대학교 과학기술연구소 2006 科學技術硏究論文集 Vol.17 No.-
In this paper, the situation of energy efficiency standards for TVs and diffusion states are analyzed and a new methodology is proposed using diffusion models and learning curves. The existing diffusion models could not explain affects from new appliances' penetration during the diffusion. But a mixed diffusion model with learning curves or learning ratio is studied to explain this penetration. The case study are implemented for TVs.