• Journal of Magnetics
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• v.22 no.1
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• pp.93-99
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• 2017

The effort attempts to investigate the influence of various non-oriented electrical steel sheets on the core loss of a switched reluctance motor (SRM). The core loss of the motor inherits a strong correlation with flux density and permeability of the material. The study involves the use of laminated 2.7 % high silicon steel suitable for the motor in view of its higher flux density and lower core loss. The accurate prediction of core loss leaves way to suggest measures for improving the performance of the SRM. The dynamic simulation measurements of a 1.5 kW, three-phase 12/8 SRM involve the finite element method (FEM) and use the data obtained experimentally from Epstein frame. The closeness of the simulated and hardware results obtained with laminations of M400-50A, DI MAX-M19 and DI MAX-M15 both for the stator and rotor, espouse a greater significance to the findings in terms of the core loss density and forge new dimensions for its use in the drive industry.

• Steel and Composite Structures
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• v.17 no.2
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• pp.159-172
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• 2014

A finite element model with the consideration of damage initiation and evolution has been developed for the analysis of the dynamic response of a composite sandwich panel subject to low velocity impact. Typical damage modes including fiber breakage, matrix crushing and cracking, delamination and core crushing are considered in this model. Strain-based Hashin failure criteria with stiffness degradation mechanism are used in predicting the initiation and evolution of intra-laminar damage modes by self-developed VUMAT subroutine. Zero-thickness cohesive elements are adopted along the interface regions between the facesheets and the foam core to simulate the initiation and propagation of delamination. A crushable foam core model with volumetric hardening rule is used to simulate the mechanical behavior of foam core material at the plastic state. The time history curves of contact force and the core collapse area are obtained. They all show a good correlation with the experimental data.

• Current Optics and Photonics
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• v.7 no.5
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• pp.496-503
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• 2023

We present a detailed analysis of the light extraction efficiency (LEE) of a core-shell nanorod light emitting diode (LED) using finite-difference time-domain (FDTD) simulations. We found that the LEE has a deep dependence on source positions and polarization directions based on the calculated LEE results for every x and z position inside the core-shell nanorod structure. The LEEs are different for the upper part (pyramid) and the lower part (sidewall) of the core-shell nanorod owing to total internal reflection (TIR) and the generated optical modes in the structure. As a result, the LEE of sidewall is much larger than that of pyramid. The averaged LEE of the core-shell nanorod LED is also investigated with variable p-GaN thickness, n-GaN thickness, and height for the design guidelines for the optimized LEE of core-shell nanorod LEDs.

• Transactions on Electrical and Electronic Materials
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• v.16 no.1
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• pp.37-41
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• 2015

The most common structure of the current transformer (CT) consists of a length of wire wrapped many times around a silicon steel ring passed over the circuit being measured. Therefore, the primary circuit of CT consists of a single turn of the conductor, with a secondary circuit of many tens or hundreds of turns. The primary winding may be a permanent part of the current transformer, with a heavy copper bar to carry the current through the magnetic core. However, when the large current flows into a wire, it is difficult to measure its magnitude of current because the core is saturated and the core shows magnetic nonlinear characteristics. Therefore, we proposed a newly designed CT which has an air gap in the core to decrease the generated magnetic flux. Adding the air gap in the magnetic path increases the total magnetic reluctance against the same magnetic motive force (MMF). Using a ferrite core instead of steel also causes the generation of low magnetic flux. These features can protect the magnetic saturation of the CT core compared with the steel core. This technique can help the design of the CT to obtain a special shape and size.

• Journal of Engineering Education Research
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• v.20 no.5
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• pp.50-58
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• 2017

The purpose of this study is to explore the core competencies of the Fourth Industrial Revolution in the major newspaper articles of social network analysis and to examine the core competencies required by each field and target. To do this, we reviewed prior research focusing on core competency concepts and core competencies of engineering students, and analyzed 227 articles related to core competencies of the 4th Industrial Revolution, focusing on five major newspapers. Through analysis, we analyzed social network with 118 refined core competency keywords. As a result of the research, it was found that core competencies of the 4th Industrial Revolution are the degree centrality in terms 'creativity', 'problem solving ability', 'convergence ability', 'collaboration ability', 'conductivity', 'software ability', 'human literacy', 'personality' order. Also, as a result of the analysis of the ego centric network by field and target, the required core competencies of university and industry were found to be different. Through these discussions, it is necessary to restructure the core competence of engineering students in order to nurture the engineering talents necessary for the 4th Industrial Revolution.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.3
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• pp.417-424
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• 2013

PURPOSE: We investigated the relationship between the segment of erector spinae during a core stability exercise according to visual control. METHODS: The subjects of this study were 20 healthy students. An 8-channel electromyograph was used to measure muscle activities of the erector spinae by segment(cervical, thoracic and lumbar) during a core stability exercise according to visual control. The collected data were analyzed using the independent t-test and Pearson-test. RESULTS: The activity of the erector spinae for all segment was higher without the vision than with. The activity of right cervical erector spinae was significantly increased by increasing the activity of the left thoracic erector spinae during a core stability exercise with vision (r= .555). The activity of left thoracic erector spinae was significantly increased by increasing the activity of the left lumbar erector spinae during a core stability exercise without vision (r= .472). CONCLUSION: There was a positive correlation between the cervical and thoracic segment of erector spinae during a core stability exercise with vision. There was a positive correlation between the thoracic and lumbar segment of erector spinae during a core stability exercise without vision.

• Architectural research
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• v.8 no.1
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• pp.25-36
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• 2006

Campus core is an essential element in a university's physical environment for symbolic importance of high educational philosophy as well as hierarchical significance of campus structure. Yet, as modern expansion develops into and out of campus core, a challenging design and planning problem for a growing university is how to integrate a new development into the existing core structure and how to expand the fast-growing development beyond the core while maintaining a symbiotic harmony between the campus core and the modern expansion. Such challenge addresses four design frameworks for symbiotic development of the campus core and the modern expansion: (1) building grouping with territorial proximity; (2) building design rules for form and texture; (3) open space network with pedestrian walkway; (4) use-programming for on-campus student community. This study aims to explore these issues with in-depth case study of the Princeton University campus in Princeton, New Jersey in the United States. The study concludes that the Princeton campus is a result from successful synthesis of all the complex design elements, especially in relationship between the old and the new; and adds further that the development of a modern university campus requires a comprehensive plan that takes into account the older buildings when conceiving the new in symbiotic relationship along with open space network as well as functional program distribution.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.545-550
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• 2015

High Temperature Superconducting (HTS) synchronous generators can be designed with either an air-core type or iron-core type. The air-core type has higher efficiency under rated rotating speed and load than the iron-core type because of the iron losses which may produce much heat. However, the total length of HTS wire in the air-core type is longer than the iron-core type because the generated magnetic flux density of the air-core type is low. This paper deals with designs of 10 MW air-core and iron-core HTS wind power generators for wind turbines. Fully air-core, partially iron-core, and fully iron-core HTS generators are designed, and various stator winding methods in the three HTS generators are also considered, such as short-pitch concentrated winding, full-pitch concentrated winding, short-pitch distributed winding, and full-pitch distributed winding. These HTS generators are analyzed using a 3D finite elements method program. The analysis results of the HTS generators are discussed in detail, and the results will be effectively utilized for large-scale wind power generation systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.233-238
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• 2016

Recently, the multi-core processor architecture is widely adopted in the embedded processors for enhancing its performance. Multi-core processors are classified either as symmetric or asymmetric. Asymmetric multicore processors are known to score higher performance and more efficient than symmetric multi-core processors. In order to study the performance enhancement of asymmetric multi-core embedded processors over the symmetric ones, the trace-driven simulation has been executed for various asymmetric embedded dual-core, quad-core, octa-core and hexadeca-core processors and compared with the symmetric ones of similar hardware budget using MiBench benchmarks as input.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.21-29
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• 2000

The Purpose of this paper is to determine the effect of the autoclave inner pressure rate, heat-up rate, tool round angle, Thickness of core, height of joggle on defects, and to minimize the defects of aircraft sandwich structure reinforced with honeycomb core occurred in autoclave processing. The results showed that the geometry of aircraft sandwich structure and tool such as tool round angle, Thickness of core, height of joggle, and the autoclave cure conditions such as inner pressure rate, heat up rate strongly affected the core movement, core wrinkle, bridge phenomenon of prepreg and depression of core that occurred in autoclave processing.