• International Journal of Aerospace System Engineering
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• 제9권2호
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• pp.1-9
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• 2022

The NEA release mechanism is used to provide restraint and release functions with low shock for critical deployment operations on solar arrays after launch. The GK3 solar array consists of 2 wings and 6 hold down points per panel. The NEA SSD9103S1 is a part of the GK3 solar array hold-down and release mechanism. Each NEA unit is equipped with two Z-diodes which provide power to a NEA unit connected in series after actuation of the fuse wire. This paper presents the hot firing test results of a quadrature NEA SSD9103S1 configuration. One output powers a maximum of 4 NEA SSD9103S1 units simultaneously. The necessary actuation pulse duration has been determined to meet margin requirement for thermal energy of minimum 4. Actuation thermal energy difference is about 6.6% between each half of two fired serial NEAs. Thermal energy margin at worst case is minimum 5.9 in case of an actuation pulse duration of 500 ms. Two series Zener impedance depend on current applied has been characterized by an additional actuation after all fuse wires are open circuit. Total number of actuation commands to the GK3 NEA unit reduce drastically from 24 in case of single NEA configuration down to 8 in case of parallel and quadrature NEA configurations. It can be accommodated by the existing HP2U Pyro design without any impact.

• 전력전자학회논문지
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• 제21권5호
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• pp.388-395
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• 2016

Electric vehicles (EV) and hybrid EVs (HEV) are designed and manufactured by GM, Toyota, Honda, and Hyundai motors. The propulsion system design process for EV requires integrating subsystem designs into an overall system model to maximize the performance of a given propulsion architecture. Therefore, high-power density and high-torque density are important attributes required for EV applications. To improve torque and power density, propulsion motors are designed for saturation during high-torque operation. The nonlinearity associated with core saturation is modeled by incorporating the cross-coupling inductances, which also behave nonlinearly. Furthermore, in EV environments, the battery is directly connected to the DC link, and the battery changes depending on the state of charge. It will be onerous if as many optimal current commands as different $V_{dc}$ were made. This paper presents the optimal current commands in the various operating condition and the current control technique in EV environments.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2002년도 봄 학술발표논문집 Vol.29 No.1 (A)
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• pp.676-678
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• 2002

In this work, we present the novel scheduling algorithm of the multimedia data retrieval for the mobile disk drive. Our algorithm is focused on minimizing the power consumption involved in data retrieval from the local disk drive. The prime commodity in mobile devices is the electricity. Strict restriction on power consumption requirement of the mobile device put unique demand in designing of its hardware and software components. State of the art disk based storage subsystem becomes small enough to be embedded in handhold devices. It delivers abundant storage capacity and portability. However, it is never be trivial to integrate small hard disk or optical disk drive in handhold devices due to its excessive power consumption. Our algorithm ARM in this article generates the optimal schedule of retrieving data blocks from the mobile disk drive while guaranteeing continuous playback of multimedia data.

• International Journal of Aeronautical and Space Sciences
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• 제15권2호
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• pp.190-198
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• 2014

The pyramidal reaction wheel arrangement is one of the configurations that can be used in attitude control simulators for evaluation of attitude control performance in satellites. In this arrangement, the wheels are oriented in a pyramidal configuration with a tilt angle. In this paper, a study of pyramidal reaction wheel arrangement is carried out in order to find the optimum tilt angle that minimizes total power consumption of the system. The attitude control system is analyzed and the pyramidal configuration is implemented in numerical simulation. Optimization is carried out by using an iterative process and the optimum tilt angle that provides minimum system power consumption is obtained. Simulation results show that the system requires the least power by using optimum tilt angle in reaction wheels arrangement.

• 한국항공우주학회지
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• 제36권12호
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• pp.1222-1228
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• 2008

㈜쎄트렉아이는 UAE의 EIAST와 함께 2008년 발사를 목표로 SI-200 표준버스시스템을 기반으로 하는 DubaiSat-1 비행모델을 개발하였다. DubaiSat-1 비행모델의 열제어계는 전력 소비의 최소화를 위해 수동 열제어를 기반으로 하되, 주요 부품에는 히터를 이용한 능동 열제어가 이뤄지도록 설계되었다. 또한 열해석 모델을 작성하여 DubaiSat-1의 임무궤도에 대해 열해석을 수행하였으며, 해석 결과를 토대로 모든 구성품이 설계 요구조건을 만족시킬 수 있도록 설계 보정 작업을 진행하였다. 또한 우주환경을 모사한 열진공시험을 수행하여 DubaiSat-1 비행모델의 열제어 성능에 대해 검토하였으며, 시험 결과와 해석 결과의 비교를 통한 열해석 모델의 보정 작업을 완료하였다.

• 한국항공우주학회지
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• 제41권11호
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• pp.921-930
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• 2013

(주)쎄트렉아이는 고해상도 전자광학카메라인 EOS-D Ver.1.0의 개발 및 검증을 성공적으로 완료하였다. EOS-D Ver.1.0 시스템은 기존 EOS-C 계열 대비 향상된 공간 해상도 및 방사학적 해상도를 갖도록 설계되었다. EOS-D Ver.1.0의 열제어계는 능동 열제어 방식과 수동 열제어 방식을 혼용하여 개발되었다. 또한, 광학계 주구조물의 수분 발산 효과에 의한 비정렬 상태를 보상할 수 있도록 초점 조절장치(refocusing mechanism)를 설계하고 이를 검증하였다. 설계를 바탕으로 실제 모델을 제작, 인증 수준의 열진공 시험을 통해 설계 여유(design margin)와 작업도(workmanship)를 확인하였다. 또한 열-수치 모델(TMM)에 대한 검증 작업을 수행하여 해석 모델이 실제 모델의 열적 특성을 잘 모사하고 있음을 확인하였다.

• 한국항공우주학회지
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• 제37권8호
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• pp.798-804
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• 2009

(주)쎄트렉아이는 400kg 급 지구관측 위성의 주 탑재체로 사용될 고해상도 전자광학카메라, EOS-C 시스템을 개발 중이다. 이 시스템은 DubaiSat-1 위성의 주 탑재체 개발을 통해 획득한 경험을 토대로 보다 향상된 광기계 및 열적 성능을 갖도록 설계되었다. 민감한 광학부품의 운용상 성능을 유지하기 위해 히터를 이용한 능동 열제어 방식이 적용되었고, 이와 더불어 히터 소모 전력을 최소화하기 위해 열 코팅 및 다층박막단열재(MLI)를 사용한 수동 열제어 방식이 적용되었다. 열해석 모델을 이용해 임무궤도에 대한 열해석을 수행하였으며, 해석 결과를 바탕으로 이 시스템의 열제어계가 설계 요구조건을 만족하는 것을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2004-2012
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• 2014

Energy storage devices are necessary to obtain stable utilization of renewable energy sources. When black-out occurs, distributed renewable power sources with energy storage devices can operate under standalone mode as uninterruptable power supply. This paper proposes a dynamic response analysis with small-signal modeling for the standalone operation of a photovoltaic power generation system that includes a bidirectional charger/discharger with a battery. Furthermore, it proposes a DC-link voltage controller design of the entire power conditioning system, using the storage current under standalone operation. The purpose of this controller is to guarantee the stable operation of the renewable source and the storage subsystem, with the power conversion of a very efficient bypass-type PCS. This paper presents the operating principle and design guidelines of the proposed scheme, along with performance analysis and simulation. Finally, a hardware prototype of 1-kW power conditioning system with an energy storage device is implemented, for experimental verification of the proposed converter system.

• International Journal of Control, Automation, and Systems
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• 제5권5호
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• pp.526-538
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• 2007

This paper presents a neural network based decentralized excitation controller design for large-scale power systems. The proposed controller design considers not only the dynamics of generators but also the algebraic constraints of the power flow equations. The control signals are calculated using only local signals. The transient stability and the coordination of the subsystem control activities are guaranteed through rigorous stability analysis. Neural networks in the controller design are used to approximate the unknown/imprecise dynamics of the local power system and the interconnections. All signals in the closed loop system are guaranteed to be uniformly ultimately bounded. To evaluate its performance, the proposed controller design is compared with conventional controllers optimized using particle swarm optimization. Simulations with a three-machine power system under different disturbances demonstrate the effectiveness of the proposed controller design.

• 제어로봇시스템학회논문지
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• 제5권4호
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• pp.489-495
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• 1999

This paper contains the design specification and detail design for a towing winch system. We analyze operating condition of the system and decide the design specification for the winch system, and also perform a detail design for the subsystem such as hydraulic winch system, control equipment and power supplier at the full scale development. The performance of designed towing winch is established by load tests and sea trial tests.