• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.320-323
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• 2009

There is many considerations of the composition development of propellant, performance analysis according to temperature, ablation condition of heat-resistant material, etc. in the solid rocket motor development process. Performance analysis of the motor according to nozzle expansion ratio is one of this process and an important factor to decide the motor performance. A Study is verified through anlaysis, motor manufacture and test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.219-222
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• 2007

This research on 2nd stage solid rocket motor of KSLV-I for performance change was carried out. Solid rocket motor shall ignite on altitude of 300km. Solid Rocket Motor performed Static Firing Test and High Altitude Test for motor performance. A study made an analysis of specific impulse variation for nozzle ambient pressure.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.40-44
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• 2007

Light rail vehicle is optimized vehicle system for complex urban circumstance. LRT systems have many merits such as improve accuracy, speediness and safety. There are many LRT systems such as monorail, tram, automated guideway transit, linear induction motor propulsion and so on. These systems have operated in Japan and other advanced countries. In Korea, local government has many projects to apply the advanced LRT system. But there are no standardized specification, performance test specification, construction specification for monorail system, linear induction motor propulsion system, tram in Korea up to now. So, we need to establish of standardized to economical construction and safety. The linear induction motor system has been usually applied in Japan subway and ART(Advanced Rapid Transit) of Canada. In Korea, the linear induction motor system has been adopted for Yongin LRT and currently under construction. This paper covers the contents and technical base for main items of rolling stock, performance standard, carbody structure, bogie, electronic unit and brake equipment in order to implement linear induction motor LRT system according to local conditions.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.58-60
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• 2009

This paper deals with force characteristic analysis of linear switched reluctance motor using dynamic simulation. First, we calculated flux density of linear switched reluctance motor according to position. Second, analyzed normal force from flux density of linear switched reluctance motor according to position. Also, analysis result compares with data that is derived through a finite element analysis, and proved validity. However, linear switched reluctance motor has non linear characteristic, hence, analysis of propulsion force do not easy using analytical method. Therefore, we presented dynamic characteristic analysis model which is consisted at motor and sensor signal part, etc., and substitute circuit constant that get using magnetic equivalent circuit method, we confirmed propulsion force.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.275-282
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• 2008

This paper presents numerical investigation of multi-phase flow in solid rocket motor nozzle and effect of multi-phases on the performance prediction of the Solid Rocket Motor. Aluminized propellants are frequently used in solid rocket motors to increase specific impulse. An Eulerian-Lagrangian description has been used to analyze the motion of the micrometer sized and discrete phase that consist of the larger particulates present in the Solid Rocket Motor. Uniform particles diameters and Rosin-Rammler diameter distribution method has been used for the simulation of different burning of aluminum droplets generating aluminum oxide smokes. Roe-FDS scheme has been used to simulate the effects of the multi-phase flow. The results obtained show the sensitivity of this distribution to the nozzle flow dynamics, primarily at the nozzle inlet and exit. The analysis also provides effect of two phases on performance prediction of Solid Rocket Motor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.203-206
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• 2008

Kick motor(KM) for KSLV-I second stage propulsion system is the main hardware that is necessary for launching satellite to it's track. The mass of the kick motor changes with combustion time because the heat insulator is ablated and propellant is used and slag is piled up. We predicted mass change with the flight time using ground combustion data of KM composed of case, propellant, nozzle, ignitor and slag. The mass prediction of kick motor can be used for calculating the two stage mass and center of gravity history.

• Journal of Power Electronics
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• v.19 no.3
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• pp.761-770
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• 2019

This paper proposes a hybrid phase windings excitation method for improving the efficiency of a 7-phase brushless DC (BLDC) motor in the electric propulsion system of a ship. The electrical losses of a BLDC motor system depend on the operating region and the number of excited phase windings (2-phase, 4-phase or general 6-phase windings). In this paper the operating region and torque/speed characteristics according to the motor rotation speed and propeller load are analyzed for a number of excitation methods. In addition, it analyzes the electrical losses of the system under each of the excitation methods in the entire operating region of the motor. In every sampling time, the proposed control method calculates the electrical loss of the system for each of the excitation methods and operates a 7-phase BLDC motor by selecting the excitation method that results a decreased electrical loss at the operating speed. The usefulness of the proposed control algorithm is verified through experimental results.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.3
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• pp.107-115
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• 1998

This paper deals with the study on injection with EPDM(Ethylene propylene dien ter polymer) the gap which narrow, long, and tubular between an ablative composite tube and a steel motor case. Small size motor assembly was designed and manufactured for man-portable air defense propulsion system. Motor assembly is consisted with steel tube, ablative composite tube and insulation rubber. Ablative composite tube was made of carbon/phenolic prepreg by rolling process and insulation rubber was made of EPDM by TPM(Trans-power molding) process. To select the insulation rubber material, we tested ablative insulation property and degradation property at first and we tested fluidity, adhesive property and hardness of EPDM rubber. Finally we designed TPM process to manufacture motor case assembly and the motor case assembly was examined by non-destructive test(X-ray).

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.802-808
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• 2019

DC motors are used extensively on shipboard, including as the ship's winch operating motor, owing to their simple speed control and excellent output torque characteristics. Moreover, they were used as propulsion motors in the early days of electric propulsion ships. However, mechanical rectifiers, such as brushes, used in DC motors have certain disadvantages. Hence, brushless DC (BLDC) motors are increasingly being used instead. While the electrical characteristics of both types of motors are similar, BLDC motors employ electronic rectifying devices, which use semiconductor elements, instead of mechanical rectifying devices. The inverter system for driving conventional BLDC motors uses a two-phase excitation method so that the waveform of the back electromotive force becomes trapezoidal. This causes harmonics and torque ripple in the phase current switching period in which the winding wire through which the current flows is changed. Researchers have studied and presented various methods to reduce the harmonics and torque ripple. This study applies a cascaded H-bridge multilevel inverter, which implements a proportional-integral speed current controller algorithm in the driving circuit of the BLDC motor for electric propulsion ships using a power analysis program. The simulation results of the modeled BLDC motor show that the driving method of the proposed BLDC motor improves the voltage waveform of the input side of the motor and remarkably reduces the harmonics and torque ripple compared with the conventional driving method.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.81-85
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• 2011

The end effect of a linear induction motor (LIM) has been known for several decades, especially in high speed operation. The exit part of the primary is not dealt as extensively as the entry part because of its minor effect. However, the exit part is one of the keys to weaken the dolphin effect, which occurs in high speed operation. In this paper, the concept of the virtual primary core is introduced, and chamfering of the primary outlet teeth is proposed to minimize the longitudinal end effect at the exit zone. For this, LIM for the high-speed train is designed and analyzed by using finite element method. Results confirm that chamfering can improve thrust performance effectively.