• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.139-143
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• 2003

Study on the ignition characteristics of combustor and gas generator for LOx-kerosene liquid rocket engine was performed experimentally through a series of combustion tests of sub-scale engine combustor and gas generator. Characteristic of gas-torch ignitor based on gaseous methane and gaseous oxygen was compared with hypergolic ignition using propellant tri-ethyl-aluminium. Gas-torch ignitor showed good performance on igniting sub-scale liquid rocket engine combustor and gas generator. It was observed that the ignition delay is also affected by the extent of nitrogen in the combustion chamber.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.123-128
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• 2006

The proposed mathematical model of the starter-generator system incorporates the motor speed, battery voltage and the desired current to estimate the moment generation capabilities of the starter-generator and the actual current of the battery system. The fundamentals for this mathematical modeling are the simulated results of the experimental data. These pertinent data are used in establishing the governing equations for the determination of motor moments, actual battery currents and efficiencies of the system's operation at different loading characteristics and speed regions. The derived equations will be used into simulation programs to predict the fuel efficiency, vehicle characteristics of a hybrid electric vehicle equipped with a transmission starter-generator which will be developed.

• 전기의세계
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• v.16 no.1
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• pp.7-13
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• 1967

There are many kinds of motors operating by rated voltage which is constant. In this paper, the characteristics of separately excited direct current motor is analyzed when its terminal voltage is varied as its load current. As for this source, direct current generator of a series field is used, and it is driven at constant speed by a primemover. The induced voltage of the generator is propotional to its load current but it saturates as its load current is large. The charateristics of motor is studied by analog computer because of the nonlinearity of generator. The results are as follows: (1) The load current and the rotor speed of motor increase as the load of motor increases. But the speed of rotor decreases for the influence of the saturation of the iron of generator field when its load current is large. (2) Decreasing the inertia of motor and increasing the inductance of the armature circuit improve the stability of motor and the region of stable state. (3) By changing the field current of the motor, the speed and the direction of rotor can be controlled in wide range.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.78-81
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• 2002

The paper discuses characteristics of an axial-flux permanent-magnet generator for a gearless wind energy system which aims to be satisfied with variable operating conditions. Design and construction of an axial-flux permanent- magnet generator with power output at 60[Hz], 300[r/min] for wind energy system is introduced. Finite-element method (FEM) is applied to analyze generator performance at variable load. The results of FE analysis show this generator Is feasible for use with a wind turbine.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.104-109
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• 2011

In this paper, after an acceleration typed ion wind generator which could format strong electric field in air was manufactured and installed, the effects of the electrode configuration and distance of acceleration type ion wind generator with triangle structure on the ion wind generation characteristics were investigated. As a result, the ion wind generator with curvature multipoint electrode could generate higher ion wind velocity and ion wind generation yield than others with multipoint electrode, curvature line electrode, line electrode structure. The ion wind generator with curvature multipoint electrode showed a peak ion wind velocity of 1.33[m/s] at 19.0[kV] and a ion wind generation yield of 0.12[m/Ws] at 15.0[kV].

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.420-427
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• 2006

The structural and leakage integrity of steam generator tubes should be sustained against all postulated loads even if a crack is present. During the past three decades, most of the efforts with respect to integrity evaluation of steam generator tubes have been focused on limit load solutions but, recently, the applicability of elastic-plastic fracture mechanics was examined cautiously due to its effectiveness. The purpose of this paper is to introduce a testing method to estimate fracture resistance characteristics of steam generator tubes with a through-wall crack. Due to limited thickness and diameter, inevitably, the steam generator tubes themselves were tested instead of standard specimen or alternative ones. Also, a series of three dimensional elastic-plastic finite element analyses were carried out to derive closed-form estimation equations with respect to J-integral and crack extension for direct current potential drop method. Since the effectiveness of $J_{IC}$ as well as J-R curves was proven through comparison with those of standard specimens taken from pipes, it is believed that the proposed scheme can be utilized as an efficient tool for integrity evaluation of cracked steam generator tubes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.129-132
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• 2008

Combustion characteristics of a gas generator for a 30 ton-class liquid rocket engine were studied. At the early stage of development, the combustion tests of the gas generator were performed by only using the nozzle which substitute for a turbine manifold exit. Then, the extension tube was applied between the gas generator and the nozzle for imitating the resonant mode of gas generator and turbine manifold. Finally, the hot-firing tests were performed on the condition of connecting the gas generator with the turbine manifold. In the paper, the step-by-step results such as temperature distribution and pressure fluctuations were analyzed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.539-546
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• 2016

With the growing interest of microgrid systems all over the world, many studies on microgrid operation are being carried out. The battery energy storage system(BESS) and the diesel generator are key equipments in the microgrid. In this paper, we analyze the characteristics of fuel consumption according to the power ratio of the diesel generator. Then, the formula to represent the unit cost of generation according to the power ratio of the diesel generator is derived. A new modeling of battery operation is presented considering the lifetime reduction according to increasing the cycles of charge/discharge operation of the battery. The methodology of determining the optimal operation of the battery and the diesel generator is presented by the use of the formula of fuel consumption of the diesel generator and the new modeling of battery operation. It is shown that this optimization methodology can be applied effectively for economical operation of the BESS and the diesel generator of a microgrid by case studies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.9
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• pp.1269-1275
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• 2015

Turbine-generator torsional response is caused by interaction between electrical transient air-gap torque and mechanical characteristics of turbine-generator shafts. There are various factors that affects torsional interaction such as fault, circuit breaker switching and generator mal-synchronizing, etc. Fortunately, we can easily simulate above torsional interaction phenomena by using ElectroMagnetic Transient Program (EMTP). However, conventional EMTP shows the incomplete response of super- synchronous torsional mode since it does not consider turbine blade section. Therefore, in this paper, we introduced mechanical-electrical analogy for detailed modeling of turbine-generator shaft system including low pressure turbine blade section. In addition, we derived the natural frequencies of modeled turbine-generator shaft system including turbine blade section and analyzed the characteristics of mechanical torque response at shaft coupling and turbine blade root area according to power system balanced/unbalanced faults.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.4
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• pp.387-392
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• 1997

This paper describes a combination surge generator for carrying out performance tests on the surge protection circuits of shipboard electrical systems. Pspice simulations were performed to decide the values of the parts required and to analyze the characteristics of the generator circuitry. The surge generator fabricated can produce four of the most common surge test waveforms : the O.5i/S/100kHz Ringwave, the 1.2/50$\mu$S voltage, the 8/20$\mu$S current, and the lO/lOOOi/S voltage wave¬forms specified in ANSI Std. C62. Source impedances of the surge generator are 12$\Omega$ in the O.5$\mu$S/100kHz mode, O.5$\Omega$ in the 1.2/50$\mu$S and 8/20$\mu$S mode, and 40$\Omega$in the l0/1000$\mu$S mode, and are determined by the ratio of the maxi¬mum open - circuit voltage to the maximum short - circuit current. Experimental results show that the surge generator provides most of the outputs required for the testing of the surge protection circuits on shipboard electrical systems.