• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.42-49
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• 2017

The solid rocket motor(SRM) consists of a motor case, igniter, propellants, nozzle, insulation, controller, and driving device. The liquid rocket propulsion systems(LRPSs) cools the nozzle by the fuel and oxidizer but SRM does not cool the nozzle. The nozzle of SRM is high temperature condition and high velocity condition so occurs the erosion by combustion gas. This erosion occurs the change of nozzle throat and reduces thrust performance of rocket. The material of Rocket nozzle is minimization of erosion and insulation effect and endure the shear force, high temperature and high pressure. The purpose of this study is to investigate the erosion characteristics of solid rocket nozzles by each combustion time. Through the structure inspection of Graphite and C-C composite, identify the characteristics of the microstructure before and after erosion.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.924-930
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• 2011

Maglev vehicle has two parts a vehicle body and a series of bogies. The vehicle body is connected through a pneumatic suspension on the bogie frame operating loads, vehicle weight and passengers, repeatedly during the service life. The bogie frame plays an important role in sustaining the weight of the vehicle body and controlling the magnets in the correct alignment to meet requirements of stable running on railway. It is also subjected to the levitation and guidance force and propulsion force generated by electromagnets and linear induction motor (LIM) respectively. To guarantee a vehicle system, it is necessary to identify a load test method with proper loads that the vehicle is expected to experience while in service. In this paper, a test method was proposed to verify the structural safety of vehicle body and bogie frame that are applied to an EMS(electromagnetic suspension)-type urban Maglev vehicle considering in case of not only running on the ground but also levitated running.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3180-3186
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• 2011

A segmented scissors type switch has been developed for the urban transit maglev demonstration line to be commercialized near Incheon International Airport in 2013. Based on the design of the previous segmented 3-way switch, the scissors switch is composed of four segmented 2-way switches up/down and left/right and a turn table in the mid point. The main function of the scissors switch is to change the running direction of the train at end terminals. The developed scissors switch is planned to be installed in front of the 102 station, which has a side platform, of the demonstration line. The total length of the switch is 65m and the distance between the up and down track centerlines is 6m. The 2-way switches and turn table are made of steel box type beams, and have their own driving unit, locking unit, control unit, levitation and propulsion rails, and so on. Installed in the factory, a 100,000-cycle continuous operation test was carried out after manual and automatic test operations. The applicapability of the developed switch was verified through the measurements of the linearity of the track after repetitive operations, the mechanical operation noise, the load of the main driving motor, the safety of the control panel, the natural frequency of the girder, the deformation of the girder, and so on.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.950-955
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• 2004

In the manufacture of liquid crystal display devices, there is a strong demand for contactless glass plate handling devices that can manipulate a glass plate without contaminating or damaging it. To fulfill this requirement, an electrostatic transportation device for glass plates is proposed. This device can directly drive a glass plate and simultaneously provide contactless suspension by electrostatic forces. To accomplish these two functions, a feedback control strategy and the operational principle of an electrostatic induction motor are utilized. The stator possesses electrodes which exert electrostatic forces on the glass plate and are divided into a part responsible for suspension and one for transportation. To accomplish dynamic stability and a relatively fast suspension initiation time, the structure of the electrode for suspension possesses many boundaries over which potential differences are formed. In this paper, an electrode pattern suitable for the suspension of glass plates is described, followed by the structure of the transportation device and its operational principle. Experimental results show that the glass plate has been transported with a speed of approximately 25.6 mm/s while being suspended stably at a gap length of 0.3 mm.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.868-876
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• 2014

Arleigh Burke(DDG-51) and Sejong warship are AEGIS destroyer of US Navy and Korea Navy. These are designed to make more than 30knots by applying a COGAG(COmbined Gas turbine And Gas turbine) system. However, the gas turbine(LM2500) in this system has a low SFC (Specific Fuel Consumption) when the warship operated low speed. So, many kinds of companies are researching the HED(Hybrid Electric Drive) system to improve this problem. The purpose of this paper is to analyze the HED system and simulate by Sejong warship data. Serveral methods were used for that purpose. More specifically, the equipment modeling are employed for regression analysis by LabVIEW. As a result, it was found that the warship installed HED system could cut their fuel bills by as much as about 80,000,000won per year.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.109-110
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• 2016

본 논문에서는 현재 운행되고 있는 선형 유도전동기의 슬립주파수 고정 방식이 아닌 선형 유도전동기를 이용한 자기부상열차의 슬립주파수와 수직력 및 추진력과의 관계를 이용, 열차의 가감속시 운행패턴에 따라 운행 중 슬립주파수가 가변할 수 있는 슬립주파수 가변패턴을 형성, 선형유도전동기 자기부상시스템에서의 에너지 효율향상 가능성을 검증하였다. 슬립주파수와 수직력, 추진력과의 관계를 이용 슬립주파수 일정 실효치전류제어 알고리즘과 슬립주파수 일정 벡터제어 알고리즘을 사용하여 운전조건과 슬립주파수를 변경하며 운전조건에 따른 가장 효율적인 슬립주파수의 패턴을 형성하였다. 이 후 모의시험과 실차를 이용한 실험을 통해 알고리즘에 대한 정당성과 실제 효율의 증가를 통해 타당성을 검증하였다. 앞선 두 가지 알고리즘을 통해 열차부상에 영향을 미치지 않는 범위의 수직력을 가지는 범위내에서 슬립주파수를 가변 운전 조건에 따른 최적의 슬립주파수에 대한 정보를 기반으로 운행 중 가변하는 슬립주파수를 자동열차운전(ATO)시스템에 적용 모의실험을 통해 그 적용가능성과 효율을 검증하였다.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.86-108
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• 2012

$CO_2$ reduction, energy security, and emission reduction are the critical issues in the current automotive industry. As one of the solutions to these issues, Battery Electric Vehicle is attracting attention recently. Advanced battery electric drive vehicle require batteries, power electronics and electrical machines to function. These devices allow the vehicle to use energy from the battery to assist in the propulsion of the vehicle. In this paper, the main feature of these technologies are briefly introduced and recent trends of patent applications are described.

• Carbon letters
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• v.4 no.3
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• pp.133-139
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• 2003

Carbon/carbon composites are ideal candidates for a number of aerospace applications including structural materials for advanced vehicles, leading edges, structures of re-entry and hypersonic vehicles and propulsion systems. One serious defect for such application of the carbon/carbon composites is their poor oxidation resistance in high temperature oxidizing environments. SiC coating was employed to protect the composites from oxidation. It is mechanically and chemically stable under extreme thermal and oxidative environments, provides good adhesion to the substrate, and offers good thermal shock resistance. The SiC layer on the nozzle machined from the carbon/carbon composites was formed by pack-cementation method. Then, erosion characteristic of SiC coated carbon/carbon nozzle was examined by combustion test using a liquid rocket motor. The erosion rates were measured as function of combustion pressure, ratio of oxygen to fuel, combustion time, density of the composites and geometry of reinforced carbon fibre in the composites. The morphology change of the composites after combustion test was investigated using SEM and erosion mechanism also was discussed.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.499-509
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• 2009

Electric vehicles (EV) are developing fast during this decade due to drastic issues on the protection of environment and the shortage of energy sources, so new technologies allow the development of electric vehicles (EV) by means of electric motors associated with static converters. The proposed propulsion system consists of two induction motors (IM) that ensure the drive of the two back driving wheels. The electronic differential system ensures the robust control of the vehicle behavior on the road. It also allows controlling, independently, every driving wheel to turn at different speeds in any curve. This paper presents the study of an hybrid Fuzzy-sliding mode control (SMC) strategy for the electric vehicle driving wheels, stability improvement, in which the fuzzy logic system replace the discontinuous control action of the classical SMC law. Our electric vehicle fuzzy-sliding mode control's simulated in Matlab SIMULINK environment, the results obtained present the efficiency of the proposed control with no overshoot, the rising time is perfected with good disturbances rejections comparing with the classical control law.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.85-90
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• 2003

To control spacecraft including satellite, we should understand precisely the performance of propulsion system and the program logic with appropriate format for satellite operations. In this study, the thruster performance functions was generated by using the best curve fitting for performance data from bi-propellant thrusters. Detailed thruster performance data are, in general, company proprietary information, therefore real firing tests were performed to understand the basic characteristics of the performance curve. Experimental rocket motor utilize liquid oxygen and kerosine as propellant and designed average thrust was 100 pound.