• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.309-319
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• 2011

We experimentally investigated lifted propane jet flames diluted with nitrogen to obtain flame-stability maps based on heat-loss-induced self-excitation. We found that heat-loss-induced self-excitations are caused by conductive heat loss from premixed flame branches to trailing diffusion flames as well as soot radiation. The conductive-heat-loss-induced self-excitation at frequencies less than 0.1 Hz is explained well by a suggested mechanism, whereas the oscillation of the soot region induces a self-excitation of lift-off height of the order of 0.1 Hz. The suggested mechanism is also verified from additive experiments in a room at constant temperature and humidity. The heat-loss-induced self-excitation is explained by the Strouhal numbers as a function of the relevant parameters.

• Composites Research
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• v.23 no.1
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• pp.17-22
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• 2010

The compressive and dynamic properties of magnetorheological elastomers were investigated as functions of magnetizable particle volume fraction, alignment of the embedded particle and magnetic force. The specimens consisted of pure and filled silicons with randomly dispersed, longitudinal and transverse aligned magnetizable particle chains. To align the embedded particles in the elastomer, the cross-linking of the elastomer composites took place in a magnetic field. The compression and dynamic tests in the absence and the presence of different magnetic forces were carried out. The modulus and loss factor of the elastomer composites increase with increasing volume fraction at the same magnetic force. The case of longitudinal alignment shows a high modulus and loss factor when compared to the case of transverse alignment or random dispersion.

• 한국벤처창업학회:학술대회논문집
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• 2021.04a
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• pp.103-108
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• 2021

코로나19로 인해 전 세계가 대 격변기에 있다. 경기 위축과 불확실성이 증대되고 있어 많은 기업과 가게 등 경제 주체들이 어려움을 겪고 있다. 이러한 상황에서 창업을 계획한다면 실패에 대한 많은 심리적 부담을 갖게 될 것이기에 더욱더 위험을 감수하고 위기를 기회로 활용하려는 창의적이고 적극적인 기업가의 태도가 필요하다. 따라서 본 연구는 기업가의 심리적 특성 변수라 할 수 있는 기업가정신과, 창업할 때 기업가가 갖고 있는 창업실패두려움 그리고, 창업자기효능감이 창업의도에 어떠한 영향을 미치는 지 알아보고자 한다. 본 연구에서는 기업가정신을 혁신성, 진취성, 위험감수성 세 가지 하위변수로 구분하였으며, 창업실패두려움도 재무적손실 두려움, 심리적손실 두려움, 경력손실 두려움으로 구분하여 각각의 하위변수들이 창업의도에 어떠한 영향을 미치는 지 알아보고자 한다. 또한 창업 상황에서 일종의 자신감이라 할 수 있는 창업자기효능감이 기업가정신과 창업의도 관계에서, 창업실패두려움과 창업의도관계에서 어떠한 매개적 역할을 하는 지 알아보고자 한다. 이를 통해 창업 분야에서 기업가정신과 창업실패두려움, 창업자기 효능감의 역할에 대한 학문적, 실무적 시사점을 도출하고자 한다.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.05a
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• pp.100-101
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• 1997

• Proceedings of the Korean Magnestics Society Conference
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• 1995.10a
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• pp.50-51
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• 1995

• Proceedings of the Korean Magnestics Society Conference
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• 1995.10a
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• pp.60-61
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• 1995

• Proceedings of the Korean Magnestics Society Conference
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• 1992.03a
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• pp.24-25
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• 1992

• Proceedings of the Korean Magnestics Society Conference
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• 1992.10a
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• pp.26-27
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• 1992

• Journal of the Korean Magnetics Society
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• v.22 no.1
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• pp.23-26
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• 2012

New digital feedback algorithm was developed to measure iron loss of soft magnetic materials under a condition of sinusoidal flux waveform. $V_{in}$(B) curve was used instead of H(B) curve to decide next input waveform in the feedback module so that adjusting phases of current waveform, flux waveform, and input waveform could be removed. The effectiveness of the developed algorithm was verified when iron loss of ferrite cores was measured under frequencies of 1 and 10 kHz.

• Journal of the Korean Magnetics Society
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• v.20 no.4
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• pp.143-148
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• 2010

This study examined the effects of sheet thickness on electromagnetic wave absorption characteristics and internal microstructure in 92.6%Fe-6.5%Si-0.9%Cr (wt%) alloy flakes/polymer composite sheets available for quasi-microwave band. The composite sheets with the thickness of 0.3, 0.4 and 0.5 mm were prepared by tape casting. A significant decrease in transmission parameter $S_{21}$ and a large increase in power loss were observed for the thick composite sheet in the frequency range of 1~5 GHz. However the permeability properties were not affected by thickness variation, while the imaginary part of complex permittivity increased with the increase of sheet thickness at 1~5 GHz. The enhanced electromagnetic wave absorption characteristics in the thicker composite sheets was attributed to the changed microstructure and the higher dielectric loss.