• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.239-242
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• 2008

Combustion Characteristic with initial port-diameter of fuel was studied in hybrid propulsion system using cylindrical single port-grain. In order to understand a variation of combustion characteristic with initial port-diameter, experimental studies were performed with the GOX and $GN_2O$ as oxidizer, and PE as fuel. As results, burning rate decreased with increase of initial port-diameter of fuel. And the variation of burning rate with using $GN_2O$ is smaller than using GOX.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.226-232
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• 1998

In this pager, we present IGBT VVVF inverters as a 1C1M propulsion system for electric car. This inverters are composed of high power IGBT's and controlled by compact control units. The control unit performs full digital control by using 32bit DSP and microconteroller. By using CAN-bus, high speed network is constructed within tow control units. The stack is simplified and optimized by using plate bus and IGBT driver units of hybrid-type.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.507-510
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• 2009

The small size of hybrid rocket using PE-$LN_2O$ was designed, constructed and launched for a development basic technology of Hybrid rocket vehicle. The hybrid engine ignition system was designed with valve system using external actuator and confirmed working without any fault. To design fuel grain an internal ballistics design was carried out, and to estimate rockets flight path an external ballistics analysis was carried out. So the rocket was designed and constructed, and the launch test proves that hybrid rocket's design was suitable. The hybrid rocket(weight : 9kg, diameter : 110 mm, height : 1.7 m) was launched successfully. But parachute was deployed on mid-flight and the mission could not finish its purposed flight. Some of problems were found in this activity but next launch vehicle will be improved.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.11
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• pp.1052-1059
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• 2011

It is conducted that power characteristic variation simulation of electric propulsion system that uses fuel cells, solar cells and a battery as power sources. Combining each power source, 400W electric propulsion system have been modeled and verified. In result, without active control logic, it is confirmed that battery's power response is faster than other power sources at starting and transient condition, fuel cell and solar cell are a major electrical power during cruise condition. After completing flight, SOC is 24.2% at the winter solstice and is 93% at the summer solstice, It is revealed that active power control for sustaining proper SOC is necessary as a securing the system safety and effective power distribution.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.967-972
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• 2015

Because of recent interests in energy conservation and prevention of environmental pollution, research related to these topics is increasing. The U.S. Navy has started to study the HED (hybrid electric drive) system in order to improve the COGAG propulsion system's fuel efficiency in AEGIS destroyers. (This ship's fuel consumption is 40% of the total fuel consumption of the U.S. Navy.) In addition, the Korean Navy is considering applications of the HED system in AEGIS destroyers. The purpose of this study is to analyze the U.S.A.'s HED system and to simulate its generating mode energy saving rate using LabVIEW. The results confirmed that the fuel savings are about 700 kg/h.

• Journal of Power Electronics
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• v.9 no.1
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• pp.51-60
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• 2009

Hybrid Electric Vehicles (HEVs) utilize electric power as well as a mechanical engine for propulsion; therefore the performance of HEV s can be directly influenced by the characteristics of the Energy Storage System (ESS). The ESS for HEVs generally requires high power performance, long cycle life and reliability, as well as cost effectiveness. So the Hybrid Energy Storage System (HESS), which combines different kinds of storage devices, has been considered to fulfill both performance and cost requirements. To improve operating efficiency, cycle life, and cold cranking of the HESS, an advanced dynamic control regime with which pertinent storage devices in the HESS can be selectively operated based on their status was presented. Verification tests were performed to confirm the degree of improvement in energy efficiency. In this paper, an advanced HESS with improved an Battery Management System (BMS), which has optimal switching control function based on the estimated State of Charge (SOC), has been developed and verified.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1164-1169
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• 2014

Recently, an interest in a hybrid system combining only the merits of the conventional wheel-rail system and Maglev propulsion system is growing as an alternative to high-speed maglev train. This hybrid-type system is based on wheel-rail method, but it enables to overcome the speed limitation by adhesion because it is operated by a non-contact method using a linear motor as a propulsion system and reduce the overall construction costs by its compatibility with the conventional railway systems. Therefore, the design and characteristic analysis of a coreless-type superconducting Linear Synchronous Motor (LSM) for 600km/h very high speed railway system are conducted in this paper. The designed coreless-type superconducting LSMs are the distributed winding model, the concentrated 1 layer winding model and the concentrated 2 layer winding model, respectively. In addition, the characteristic comparison studies on each LSM are conducted.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.526-529
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• 2009

In this study, we analyze the characteristic of burning classified by a propellant according to a flux of an oxidizer to analyze propellant regression distance in accordance with a thrust control and burning time of hybrid rocket using hybrid combustor of Lab-Scale. To control a flux of an oxidizer, we design flow control system to regulate the mount of opening and shutting of a needle valve by a driving of stepping motor by a combination the needle valve with stepping motor. We derive the relationships between mass flow rate and regression rate according to a propellant through the oxidizer flux change. While doing the thrust control, we estimate regression distance through the oxidizer flux in accordance with thrust and confirm the creditability through the actual thrust control burning experimentation.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.635-641
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• 2016

In order to drive a hybrid propulsion device which combines an engine and an electric propulsion unit, battery packs that contain dozens of unit cells consisting of a lithium-based battery are used to maintain the power source. Therefore, it is necessary to more strictly manage a number of battery cells at any given time. In order to manage battery cells, generally voltage, current, and temperature data under load condition are monitored from a personal computer. Other important elements required to analyze the condition of the battery are the internal resistances that are used to judge its state-of-health (SOH) and the open-circuit voltage (OCV) that is used to check the battery charging state. However, in principle, the internal resistances cannot be measured during operation because the parallel equivalent circuit is composed of internal loss resistances and capacitance. In most energy storage systems, battery management system (BMS) operations are carried out by using data such as voltage, current, and temperature. However, during operation, in the case of unexpected battery cell failure, the output voltage of the power supply can be changed and propulsion of the hybrid vehicle and vessel can be difficult. This paper covers the implementation of a high safety battery management system (HSBMS) that can estimate the OCV while the device is being driven. If a battery cell fails unexpectedly, a DC power supply with lithium iron phosphate can keep providing the load with a constant output voltage using the remainder of the batteries, and it is also possible to estimate the internal resistance.