• Journal of Magnetics
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• v.18 no.4
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• pp.481-486
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• 2013

An electromagnetic launcher (EML) system accelerates and launches a projectile by converting electric energy into kinetic energy. There are two types of EML systems under development: the rail gun and the coil gun. A railgun comprises a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail, but the high mechanical friction between the projectile and the rail can damage the projectile. A coil gun launches the projectile by the attractive magnetic force of the electromagnetic coil. A higher projectile muzzle velocity needs multiple stages of electromagnetic coils, which makes the coil gun EML system longer. As a result, the installation cost of a coil gun EML system is very high due to the large installation site needed for the EML. We present a coil gun EML system that has a new structure and arrangement for multiple electromagnetic coils to reduce the length of the system. A mathematical model of the proposed coil gun EML system is developed in order to calculate the magnetic field and forces, and to simulate the muzzle velocity of a projectile by driving and switching the electric current into multiple stages of electromagnetic coils. Using the proposed design, the length of the coil gun EML system is shortened by 31% compared with a conventional coil gun system while satisfying a target projectile muzzle velocity of over 100 m/s.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3455-3459
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• 2014

This paper reports the design and experiments for a high drive force of projectile in a coil gun system. Currently, the coil gun has been studied to apply an electromagnetic launcher. A coil gun launches a projectile by the attractive magnetic force of the electromagnetic coil. The drive force of projectile is proportional to the magnetic force generated by the electromagnetic coil. The current affects the life of the coil and the current limit exists. Therefore, the coil gun design, which does not exceed the current limit and the magnetic forces are at the maximum, is required. For this purpose, this study calculated the magnetic flux density and forces of the coil gun system and determined the current limit of the coil using the Onderdonk's equation. Based on the design result, a prototype was manufactured and an experiment was conducted to measure the muzzle velocity of the projectile. The fired projectile was analyzed using a CCD camera, and the muzzle velocity was 21m/s. In addition, a comparison of the experimental value and analysis value using commercial electromagnetic analysis software MAXWELL revealed an error of approximately 9.5%.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.125-128
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• 1994

One of the abnormal motions of the projectile in the coil gun is spinning. It is found that the spinning force is closely related with air gap distance. Modified and detail analysis for the spinning is suggested in this paper. Two reasons for spinning force and Lorentz force affecting on the spinning are introduced. Nutation, which is a result of spinning, is explained there after.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.118-123
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• 2018

Coil guns are known worldwide as inexpensive space launch vehicles. The principle of Fleming's right-hand rule allows the coil gun to accelerate the projectile by applying enormous voltage to the solenoid coil. This study was performed to improve the speed of the coil gun using MATLAB, a commercially available numerical program for high launching force of electromagnetic projectiles. To maximize the speed of the projectile, the largest coil of American wire gauge was used, and the number of windings in the radial and axial directions of the solenoid coil was optimized. Optimal length of the projectile was obtained by calculating the optimal aspect ratio between the axial length of the solenoid coil and the length of the projectile.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.408-412
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• 2014

An electromagnetic launching system presents a viable projectile propulsion alternative with low cost and minimal environmental drawbacks. A coil gun system propels a projectile using an electromagnetic force and the system is mainly employed in military weapon systems and space launch systems. In this paper, we perform optimization design to improve the muzzle velocity by analyzing the sensitivity. The muzzle velocity, which is the most important design function variable, is affected by design variables including the number of axial turns in the electromagnetic coil, number of radial turns in the electromagnetic coil, initial distance between the projectile and the coil, inner radius of the electromagnetic coil, and length of the projectile. An orthogonal arrays matrix is configured, and a finite element analysis is performed utilizing the commercial electromagnetic analysis software MAXWELL. The muzzle velocity of the optimal design is 62.4% greater than that of the initial design.

• Journal of the Korean Magnetics Society
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• v.2 no.1
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• pp.69-74
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• 1992

This paper describes the energy and speed characteristics of an induction coil-gun. The coil-gun has some merits that it can be easily installed and repeatedly used many times, it does not damage mechanically in the course of launch and the force exerted on the projectile is distributed uniformly. An equivalent circuit is employed for modeling the coil-gun. The circuit equations and equation of motion are then derived based on the equivalent circuit. These equations are solved numerically by using Runge-Kutta method. Finally the energy transfer ratios are obtained according to the variations of the resonant frequency of driving circuit and charging voltage of capacitors. The muzzle velocities of projectile are also obtained according to the variations of electrical conductivity and initial position of projectile, firing angle of driving circuit, charging voltage of capacitor and resistance of driving coil, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.7
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• pp.367-372
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• 2006

A novel coil gun type actuator has been proposed and tested for its possibility as an actuator for a high voltage circuit breaker by experimental method. The 20kJ capacitor bank with the electrolytic condensers was charged up to 500V and discharged to a couple of 100 turn coils connected with parallel through a thyristor switch. The repulsive force between coil and the actuator made by copper conductor of 20kg reached up to 23,000 N, and over 800J of energy was transferred to the kinetic energy of the conductor. The experimental results showed that the coil gun type actuator has a good possibility for the high voltage circuit breaker.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.120-123
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• 1994

The purpose of this paper is to describe the mutual inductance between two non-coaxial circular coils in coil gun. As being in many electromagnetic applications, one of them is fixed and the other one is moving and, being not supported, its axis may not coincide with the axis of the fixed coil. This paper presents a method for the calculation of the mutual inductance in case of non-coaxial coupled coils, the characteristics of this inductance and experimental results. For the computation, the complete elliptic integrals formula and mesh matrix technique were introduced. This method enables accurate results from relatively simple procedure and calculation program.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.155-156
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• 2015

This paper proposes a high efficiency wireless power transfer system with an asymmetric 4-coil resonator. It presents a theoretical analysis, an optimal design method, and experimental results. In the proposed asymmetric 4-coil system, the primary side consists of a source coil and two transmitter coils which are called intermediate coils, and in the secondary side, a load coil serves as a receiver coil. In the primary side, two intermediate coils boost the apparent coupling coefficient at around the operating frequency. Because of this double boosting effect, the system with an asymmetric 4-coil resonator has a higher efficiency than the conventional symmetric 4-coil system. The prototype operates at 90 kHz ofswitching frequency and has 200 mm of the power transmission distance between the primary side and the secondary side. An AC-DC overall system efficiency of 96.56% has been achieved at 3.3 kW of output power.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.95-98
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• 2010

The Electro Magnetic (EM) Acceleration and Deceleration (ACC/DCC) system of the Ferromagnetic Ball(FB) is the linear motor's final structural development which can be used for devices that conserve energy, gaming or rail gun. By accelerating the FB within the coil structure, it is difficult to utilize the FB's magnetizing feature via the ACC/DCC system. There is much monopole space inside the monopole coil. By using this particular feature of the FB, starting coil and Monopole Coil Structure (MCS) can be structurally separated and another simple electric related control system can be experimented for further development. For the purpose of development a review is needed of the control system of both basic stepper motor and BLDC motor.