• Journal of Drive and Control
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• v.9 no.1
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• pp.1-9
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• 2012

Nowadays, various researches about eco-friendly vehicles such as hybrid electric vehicle, fuel cell vehicle and electric vehicle have been actively carried out. Since most of these green cars have electric motors, the regenerative energy technology can be used to improve the fuel economy and the energy efficiency of vehicles. The regenerative brake is an energy recovery mechanism which slows a vehicle by converting its kinetic energy into electric energy, which can be either used immediately or stored until needed. This technology plays a significant role in achieving the high energy usage. However, there are some technical problems for controlling the regenerative braking and the electro-hydraulic brake during switching at transient region. In this paper, the performance simulator for fuel-cell vehicle is developed and transient response characteristics of the regenerative braking system are analyzed in the various driving situations. And the hardware-in-the-loop simulation of electro-hydraulic brake is performed to validate the transient characteristics of the regenerative braking system for fuel-cell electric vehicle.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.605-610
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• 1997

A simple dynamic model is developed for the transient simulation of the nuclear power reactor. The dynamic model includes the normalized neutron kinetics model with reactivity feedback effects and the core thermal-hydraulics model. The main objective of this paper demonstrates the capability of the developed dynamic model to simulate various important variables of interest for a nuclear power reactor transient. Some representative results of transient simulations show the expected trends in all cases, even though no available data for comparison. In this work transient simulations are performed on a microcomputer using the DESIRE/N96T continuous system simulation language which is applicable to nuclear power reactor transient analysis.

• Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.1-9
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• 2010

As the rocket KSLV-1 called NARO was launched lately, development of domestic rocket technology has been accelerated elastically. Since the rocket technology needs a lot of empirical data, a variety of experiments should be done and lots of time have to be spent for accumulating the foundation of technology. However using a computer can be the solution to close a gap of technique because the simulation can be executed in short time against real experiments and calculate a multiplicity of cases easily. In this research, the transient analysis of turbopump-fed liquid rocket system was worked by the one dimensional modeling. The rocket system consists of the modulized components that are engine, turbopump and so on. For 70 ton class system, the rocket transient process of starting was studied and the performance analysis in steady condition was achieved. In addition, the estimation of nozzle internal flow was investigated by using a nozzle coefficient.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1359-1367
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• 2004

The demand of vacuum pump has been increased in the process of semi-conduct manufacturing, as a core component. The response of the system for vacuum pump performance test can be utilized to assess the system and to obtain the reliability of the apparatus for the test. The system consists of gas supply tank, pressure chamber, measurement chamber and transmission line. Transient analysis for compressible fluid has been conducted to evaluate the dynamic characteristic of the volume terminated transmission line. Numerical approach based on the method of characteristics is used for the analysis. The response is evaluated with the important parameters for the system: i.e., length and diameter of the line, volume of the terminal tank. Using the numerical results, pumping speeds are calculated and then compared to the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.96-101
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• 2008

The field of load modeling has attracted the attention since it plays an important role for improving the accuracy of stability analysis and power flow estimation. Also, load modeling is an essential factor in the simulation and evaluation of power system performance. However, conventional load modeling techniques have some limitations with respect to accuracy for nonlinear and composite loads. Thus, precision load modeling technique and reasonable application method is needed for more accurate power system analysis. In this paper, we develop an intelligent load modeling method based. on neural network and application techniques for power system. The proposed method makes it possible to effectively estimate the load model for nonlinear models as well as linear models. Reasonable application method is also proposed for stability analysis. To demonstrate the validity of the proposed method, various experiments are performed and their results are presented.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.177-186
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• 2018

This paper deals with the idea to replace the usual high-level sine sweep test on shaker at system level, very severe, by a low level one completed by a transient test in the same configuration, in order to be more representative of the real environment, thus limiting over testing and improving the payload comfort. The problem of the transient test specification is first discussed. The proposed solution is to derive from LV/SC coupled analyses a shock response spectrum corresponding to two damping ratios. Then, the question of adequate shock synthesis is tackled. A new method with a given spectrum is considered for better potential and accuracy than the usual wavelets. A campaign on the Intespace bi-shaker devoted to system level showed its capability to perform the resulting test with one spectrum. First investigations to extend this approach to two spectra are in progress.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.4
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• pp.220-228
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• 2002

The cool-down performance after soaking is very important in an automotive air-conditioning system and is considered as a key design variable. Therefore, transient characteristics of each system component are essential to the preliminary design as well as steady-state performance. The objective of this study is to develop a computer simulation model and ostinato theoretically the transient performance of an automotive air-conditioning system. To do that, the mathematical modelling of each component, such as compressor, condenser, receiver/drier, expansion valve, and evaporator, is presented first of all. The basic balance equations about mass and energy are used in modelling. For detailed calculation, condenser and evaporator are divided into many sub-sections. Each sub-section is an elemental volume for modelling. In models of expansion valve and compressor, dynamic behaviors are not considered in this analysis, but the quasisteady state ones are just considered, such as the relation between mass flow rate and pressure drop in expansion device, polytropic process in compressor, etc. Also it is assumed that there are no heat loss and no pressure drop in discharge, liquid, and suction lines. The developed simulation model is validated by comparing with the laboratory test data of an automotive air-conditioning system. The overall time-tracing properties of each component agreed well with those of test data in this case.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.8
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• pp.410-417
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• 2005

This paper analyses the transient phenomena against single line to ground fault and lightning surge on underground power cable systems. For analysis in various fault conditions, several actual underground power cable systems are modeled using ATP In ground fault, the transient characteristic of the conductor and the sheath according to the fault current and the installation types of CCPU are analysed. In lightning surge strokes, the various unbalanced conditions including the length of crossbonded lead, the breakdown of CCPU and distance unbalance are considered. This paper is expected to contribute the establishment of proper protection methods against transients on underground power cable systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1943-1949
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• 1997

In this paper, the analysis of the shift transient characteristics for the Ravigneaux type automatic transmission has been carried out using dynamic models of the automatic trnasmission. It is necessary to understand the overall system including multi-plate clutch, band brake, one way clutch, and planetary gears. The equations of motion are derived from the dynamic models of the automatic transmission. The GUI computer simulation program has been developed to analyze the shift transient characteristics of the vehicle equipped with the Ravigneaux type automatic transmission.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.10
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• pp.487-495
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• 2005

This paper reviews the characteristic of thermal and temperature of oil field cable in transient state such as grounding fault and lightning surge. For analysis in various conditions, many actual underground power cable systems are modeled using ATP. These results are applied for the examination of temperature increase when the single line to ground fault by the breakdown of insulation part and hitting of lightning surge are occurred. The inner part temperature of OF cable is analysed according to the various kinds of cable using the thermal model of transient state. The temperature increase of sheath and crossbonded lead bv fault current is also analysed using IEC 60949.