• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.947-948
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• 2007

A superconducting synchronous motor with rotating field coil has been designed. This rotating field coil is composed of high-temperature superconducting(HTS) wire but the stationary armature windings are composed of conventional copper wire. In this paper a 5MW class synchronous motor with rotating HTS coil is designed. This motor is aimed to be utilized for ship propulsion so it has very low-speed. Firstly an air-cored type has been designed, which does not have any iron core both at the field and at the armature teeth. Secondly several iron-cored rotor types are considered to reduce expensive HTS wire cost.

• 품질경영학회지
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• 제49권3호
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• pp.255-268
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• 2021

Purpose: We sought to understand why a high-speed rotating projectile featuring a fuze-and-body assembly sometimes exhibited airburst, and we intended to improve the flight stability by eliminating airburst. Methods: We performed characteristic factor analysis, structural mechanics modeling, and dynamic modeling and simulation; and we scheduled firing tests to discover the cause of airburst. We used a step-by-step procedure to analyze the reliability function for selecting the bonding force standard that prevents airburst. Results: The 00MM high-speed rotating projectile features a fuze bonded to a body assembly; the bonding sometimes can break on firing. The resulting contact force, vibration and roll damping during flight generated yaw. Flight became unstable; fuze operation triggered an airburst. Our reliability test improved the bonding force standard (the force was increased). When the bonding force was at least the minimum required, a firing test revealed that airburst/flight instability disappeared. Conclusion: Analysis and identification of the causes of flight instability and airburst render military training safer and enhance combat power. Ammunition must perform as designed. Our method can be used to set standards that improve the performances of similar types of ammunition.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.1-4
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• 2011

Detonation is useful phenomena to get an effective thrust for aerospace vehicle. Fast pressure rise of detonation provides a cycle close to the constant volume system to use energy efficiently. From this point detonation can be used as an aerospace engine system. There are several types of detonation engine; pulse detonation engine (PDE) which provides a thrust by detonation intermittently, and oblique detonation engine (ODE), spin detonation engine (SDE), and rotating detonation engine (RDE) which, on the other hand, provide a continuous thrust.

• 연구논문집
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• 통권29호
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• pp.101-109
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• 1999

Presented in this paper is a new method of identifying the critical speed of rotor-bearing systems without actually reaching at the critical speed itself. Using the method, it is not only possible to calculate the critical speed by measuring a series of rotor responses at much lower rotating speeds away from and without reaching at the critical speeds but also the damping ratio and eccentricity of the system can be identified at the same time. Two types of test rotors were tested on the Rotor Dynamics Test Facility at the Rotordyn-amics Lab, KIMM, and the theory has been confirmed experimentally. The method can be adopted to monitor changes of the dynamic characteristics of critical rotating machinery before and after overhauls, repairs, exchanges of various parts, or to detect trends of direction of subtle changes in the dynamic characteristic parameters over a long periods of time.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1790-1800
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• 2006

Dynamic behavior of flexural-torsional coupled vibration of rotating beams using the Rayleigh-Ritz method with orthogonal polynomials as basis functions is studied. Performance of various orthogonal polynomials is compared to each other in terms of their efficiency and accuracy in determining the required natural frequencies. Orthogonal polynomials and functions studied in the present work are: Legendre, Chebyshev, integrated Legendre, modified Duncan polynomials, the special trigonometric functions used in conjunction with Hermite cubics, and beam characteristic orthogonal polynomials. A total of 5 cases of beam boundary conditions and rotation are studied for their natural frequencies. The obtained natural frequencies and mode shapes are compared to those available in various references and the results for coupled flexural-torsional vibrations are especially compared to both previously available references and with those obtained using NASTRAN finite element package. Among all the examined orthogonal functions, Legendre orthogonal polynomials are the most efficient in overall CPU time, mainly because of ease in performing the integration required for determining the stiffness and mass matrices.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.953-957
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• 1994

A performance prediction method is presented in this paper for design of a rotating machinery having power split/circulated transmisson with slip elements and planetary gears. And internal power flow patterns of such systems are theoretically analyzed by using mathematical modeling. To estimate usefulness of the designed machinary, geometrical approach has been adopted through the performance locus diagram which represents overall characteristics of the system. This gives us complect prediction of the qualitative performane and effects of design factors such as system layout, types and gear ratios of planetary gears and disign parameters of slip elements. The results for one of them are compared with experimental ones using dynamometer for verification.

• 한국분말재료학회지
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• 제1권2호
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• pp.145-152
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• 1994

Atomizing mode and powder characteristics of CuA1Ni base shape memory alloy in rotating disk atomization were investigated in accordance with disk materials and additional elements. Produced powders were classified into two types of spherical and flake shape. In the case of CuAlNiBTi and CuAlNiZr alloy, high yield rate and fine powder were obtained. This tendency was same when we used oxide coated disks. We concluded that this results were steno from the wetting characteristics change between molten metal and disk surface. Especially, due to the reactive properties of Ti and Zr with ceramic disk, the change of atomizing appearance and powder characteristics were noticeable.

• 연구논문집
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• 통권33호
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• pp.183-190
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• 2003

Today, We have used many electronic equipment such as computer, TV, cellular phone and so on. These equipment radiate a large amount of EMI(Electromagnetic interference) which is occurred trouble of airplane, medical equipment, communicate equipment, and especially, human health. So, Ni mesh fabrication for EMI shielding by continuous electroforming process was investigated. Continuous electroforming apparatus was made by means of rotating cathode drum. And We investigated the characteristics of two types of Ni electroforming solution. One was made by laboratory and the other was produced by M cooperation. The grain size increased with increasing current density and bath temperature, and decreasing rotating speed of cathode drum. EDX results indicate that the Ni mesh electroformed by the KIMM solution is composed of pure Ni. But the Ni mesh electroformed by the M cooperation solution has Ni and S element. The incorporation of S element in the Ni mesh has a profoundly effect on mechanical properties such as hardness, internal stress and so on.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1414-1416
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• 2000

In the future light rail vehicle is more attractive than subway, because of construction time and cost. For light rail vehicle are two types of traction motors. one is traditional rotating type and the other is linear motor. Linear motor is not better in consideration of efficiency and power factor than rotating type. But the motor needs no translation equipment for linear motion and with them can be constructed low floor vehicle. In this paper will be designed a linear induction motor with consideration of operational condition and analysed operating characteristics using FEM program and equivalent circuit.

• 한국막학회:학술대회논문집
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• 한국막학회 1992년도 추계 총회 및 학술발표회
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• pp.53-54
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• 1992

In this study characteristics of dynamic filters utilizing Taylor vortices were investigated both experimentally and theoretically. With fine silica slurry of 4.0 $\mu$m in average size experiments were conducted in Taylor vortices generated between the rotating inner cylinder consisting of microfiltration membrane of 1.2 $\mu$m in average pore size and the stationary outer cylinder. The diameter of the inner cylinder was 5.2 cm. Four outer cylinders having different diameters were manufactured and therefore four types of dynamic filters having the different ratio of the annular gap to the inner cylinder radius, i.e. 0.17, 0.33, 0.54, 0.65, were used as the experimental apparatus, as shown in Fig. 1.