• 전기의세계
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• v.18 no.4
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• pp.7-15
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• 1969

In this method the condenser excite winding has the phase angle of 90 electrical degree, with the load winding in stator. The condenser excite wing is connected with the condenser while the load winding is with the full rectifer. Direct and quardrature axis components of rotating field winding are composed, of balanced two phase winding, and each one of them is connected with half wave rectifiers. Initically, small amount of lead current can be induced at the condenser excite winding by residual magnetism of rotor. The induced lead current forces the rotating field winding to be excited by synchronous alternating magnetic field. The speed electromotive force, there for, induced in rotating field winding shall electro magnetize the rotating field pole by rotating half wave rectifiers. In the case of the charging generator directly coupled with engines at the operation of wide range speed, the generated region, such as vehicles, aircraft, ships etc, is occured. In conclusion, we can take the advantage of, omitting of voltage regurator and current limiter for charging load and reducing the consumption of fuel using the generated region which can be devided in to Impossible generated region, Generated region, and suspension generated region.

• New & Renewable Energy
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• v.7 no.3
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• pp.59-66
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• 2011

Recently, an UAV using green energy for propulsion has been developed due to exhaustion of fossil fuel. This aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, and/or batteries. Especially solar cells are installed in HALE UAV and flight tests are performed in the stratosphere. Although the solar powered UAV has the advantage of zero emission, its energy conversion efficiency is low and operation time is limited. Therefore, the solar powered UAV has been designed to operate with the secondary battery obtaining flexibility of energy management. In this study, we suggest the new operational concept of the solar powered UAV using directed-energy rayed from the surface of earth to UAV. An UAV is able to secure additional power through attaching solar cell to the lower surface of elevator. As a result, the additional energy supplied by directed-energy can improve the energy management and operational flexibility of the solar powered UAV.

• Proceedings of the KWS Conference
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• 1995.10a
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• pp.208-211
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• 1995

Five cast gamma titanium aluminides, Ti-45~48%Al-2%Nb-2%Cr (nominal composition in at. %), were laser welded and their weld cracking susceptibilities were evaluated. Laser power, traversing rate and preheat temperature were systematically varied to generate a series of welds exhibiting a wide range of cooling rate ($100^{\circ}C/s-10,000^{\circ}C/s$). As Al content increased and the weld cooling rate decreased, solidification cracking susceptibility increased while solid-state cracking susceptibility decreased. Through laser beam energy input control and preheat, it was determined possible to produce high quality laser welds.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.27-35
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• 1998

Ni-based heat resisting alloys are commonly used for high temperature applications such as in aircraft engines and gas turbines. In this work, the machinability of Nimonic 263 alloy is investigated with respect to optimum tool type and cutting conditions for both continuous and discontinuous machining as well as weld region. Among the five types of tools tested, K25 tool experienced the least of damage in machining the weld region. Furthermore, despite their superior high temperature hardness, Si-Al-O-N and CBN tools peformed poorly in machining Nimonic 263.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.30-35
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• 2001

Nickel-based heat resisting alloys are commonly used for high temperature application such as in aircraft engines and gas turbines. In this paper, the machinability of Nickel-based heat resisting alloys was investigated with respect to the wear and the chip formation by tool type and cutting condition. Relationship between three types of tool and chip formation was experimentally investigated. Among the three types of tool tested, coated tools(CVD, PVD) ara available for the difficult-to-cut-materials such as Nickel-based heat resisting alloys and etc.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.104-111
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• 2005

Gas turbine engines for aircraft are usually operated at the altitude condition which is quite different from the ground condition. In order to measure the precise performance data at the altitude condition, the engine should be tested at the altitude condition by a real flight test or an altitude simulation test with an altitude test facility. In this paper, the present state of the altitude test facility and the test technologies at urn(Korea Aerospace Research Institute) will be introduced.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.264-269
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• 2000

Nickel-based heat resisting alloys are commonly used for high temperature applications such as in aircraft engines and gas turbines. In this paper, the machinability of Nickel-based heat resisting alloy was investigated with respect to the wear and the chip formation by tool type and cutting condition. Relationship between three types of tool and chip formation was experimentally investigated. Among the three types of tool tested, coated tools(CVD, PVD) are available for the difficult-to-cut-materials such as Nickel-based heat resisting alloy and etc..

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.67-72
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• 2019

In manufacturing sites that process and produce parts in large quantities for the automotive and electronics industries, users require the reducing of costs and shortened delivery times. To meet these demands, an increase in the number of processes and an decrease in assembly times need to be addressed. Gantry loaders currently on the market in Korea are mostly used for processing lightweight and simple shapes and are not suitable for conveying and processing complex shapes such as automobile engines and aircraft parts. This makes it difficult to mount the material in place. This study aims to smoothen the transportation of complex shapes through the development of jigs and various approaches in the installation of the feed shaft by researching the gantry loader system for transporting multiple materials with complex shapes.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.19-24
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• 2010

The demands for small, high performance and high loaded aircraft compressor are increased in the world. But the design requirements become increasingly complex to design these high technical engines, the requirement of the design optimization become increased. The optimal design result of several disciplines show different tendencies and nonlinear characteristics of the compressor design, the multidisciplinary design optimization method must be considered in compressor design. Therefore, the artificial Neural Net method is adapted to make the approximation model of 3-stage axial compressor design optimization for considering the nonlinear characteristic. At last, the optimal result of this study is compared to that of previous study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.491-498
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• 2003

In this paper, dynamic characteristics of an epicyclic gear train considering Coriolis effect have been studied. High speed transmissions such as in an aircraft engines will be strongly influenced by Coriolis effect. Gear meshes were modelled as springs and dampers with periodically varying mechanical constants with time. The loci of planet gear, sun gear. and carrier were analyzed. Maximum values of mesh forces between sun gear and planet gear(S/P) as well as between planet gear and ring gear(P/R) have been simulated as function of rotating speed.