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216 results on '"Choi, Hyo-Sang"'

28. Phase transition between pressure and heat release oscillations in hybrid rocket combustion

Author

Kang， Sang Hun, Lee， Changjin, and Choi Hyo Sang

Subjects
Phase difference, 0209 industrial biotechnology, Phase transition, Materials science, business.product_category, Mechanical Engineering, Direct numerical simulation, 02 engineering and technology, Mechanics, Combustion, Vortex, Physics::Fluid Dynamics, 020303 mechanical engineering & transports, 020901 industrial engineering & automation, 0203 mechanical engineering, Rocket, Mechanics of Materials, Low frequency instability, Physics::Chemical Physics, business, Equivalence ratio
Abstract

To understand the initiating mechanism of low frequency instability (LFI) in hybrid rocket combustion, numerical calculation was performed using a direct numerical simulation (DNS). Special attention was paid to the effect of the equivalence ratio on the shift in the phase difference between pressure (p’) and heat release oscillations (q’). A change in the equivalence ratio was considered by varying the temperature and composition of the combustion gas that entered into the post combustion chamber. In the obtained results, additional combustion was successfully simulated along with a vortex generation over the backward step, and combustion pressure and heat release oscillations were clearly reproduced as small vortices that move downward. In addition, the obtained results confirmed that the phase difference between pressure and heat release oscillations shifted because of the changes in the propagation speed of the pressure wave when the temperature of the combustion gas changes.

Published
2019

41. Analysis of fault current limiting characteristics according to the fault angle in an integrated three-phase flux-lock type superconducting fault current limiter

Author

Chung-Ryul Park, Ho-Ik Du, Byoung-Hwan Choi, Byoung-Sung Han, Choi, Hyo-Sang, and Young-Hee Han

Subjects
Superconductivity -- Analysis, Electrical cables -- Fault location, Electrical cables -- Analysis, Business, Electronics, Electronics and electrical industries
Abstract

The fault current limiting characteristics are examined according to the fault angle in the integrated three-phase flux-lock type superconducting fault current limiter (SFCL) in the fault type such as the single-line-to-ground fault, the double-line-to-ground fault and the triple-line-to-ground fault. The results have confirmed that the SFCL has a same current limiting rate irrespective of a fault angle in the same fault type.

Published
2008

45. Shunt-assisted simultaneous quenches in series-connected resistive SFCL components

Author

Hyun, Ok-Bae, Cha, Sang-Do, Kim, Hye-Rim, Choi, Hyo-Sang, and Hwang, Si-Dol

Subjects
Superconductors -- Research, Superconductive devices -- Research, Thin film devices -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Shunt-assisted simultaneous quenches in series-connected resistive superconducting fault current limiter (SFCL )components are examined and discussed.

Published
2003

46. Current limiting characteristics of flux-lock type high-Tc superconducting fault current limiter with control circuit for magnetic field

Author

Lim, Sung-Hun, Kang, Hyeong-Gon, Choi, Hyo-Sang, Lee, Seong-Ryong, and Han, Byoung-Sung

Subjects
Superconductive devices -- Research, Superconducting magnets -- Research, Superconductors -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A flux-lock high temperature superconducting fault current limiter (HTSC-FCL) is described and discussed.

Published
2003

47. Resistance development in superconducting fault current limiters prior to quench completion

Author

Kim, Hye-Rim, Hyun, Ok-Bae, Choi, Hyo-Sang, Cha, Sang-Do, and Oh, Je-Myung

Subjects
Superconductive devices -- Research, Superconductors -- Research, Business, Electronics, Electronics and electrical industries
Abstract

The resistance development in resistive superconducting fault current limiters (SFCL) based on YBCO thin films prior to quench completion is examined and discussed.

Published
2003

48. Switching properties of a hybrid type superconducting fault current limiter using YBCO stripes

Author

Choi, Hyo-Sang, Hyun, Ok-Bae, Kim, Hye-Rim, and Park, Kwon-Bae

Subjects
Superconductive devices -- Research, Limiter circuits -- Research, Electrical equipment and supplies industry -- Research, Electric power systems -- Research, Electrical engineering, Business, Electronics, Electronics and electrical industries
Abstract

A hybrid type of superconducting fault current limiter (SFCL) is described and discussed. It consists of transformers and resistive superconducting switches.

Published
2002

49. Quench properties of Y-Ba-Cu-O films after overpowering quenches

Author

Choi, Hyo-Sang, Kim, Hye-Rim, Hyun, Ok-Bae, and Kim, Sang-Joon

Subjects
Superconductors -- Research, Thick films -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Y-Ba-Cu-O films were studied following overpowering quenches to determine their quench properties.

Published
2001

50. Initial quench development in uniform Au/Y-Ba-Cu-O thin films

Author

Kim, Hye-Rim, Choi, Hyo-Sang, Lim, Hae-Ryong, Kim, In-Seon, and Hyun, Ok-Bae

Subjects
Limiter circuits -- Research, Superconductors -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Resistive superconducting fault current limiters were studied to determine the initial quench development process.

Published
2001

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