• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1898-1900
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• 1999

The possible origins of instabilities observed in high-voltage p-i-n devices were investigated. It was concluded that the temporary changes of electrical characteristics may be due to the changes of the physical parameters of gold acceptor, while the permanent changes are due to process-related factors.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.39-44
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• 2001

The thermocapillary flow in a differentially heated cylindrical liquid bridge under steady rotation of the hot disk is considered in the limit of zero capillary number. Steady flow states and their three-dimensional stability are calculated numerically. A linear stability analysis reveals that the most dangerous perturbations are oscillatory with azimuthal wavenumber m=1 or m=2 depending on the parameters.

• 천문학회지
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• 제37권5호
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• pp.547-551
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• 2004

We showed that magnetic fields are generated in the plasma which have the temperature inhomogeneities. The mechanism is the same as the Weibel instability because the velocity distribution functions are at non-equilibrium and anisotropic under the temperature gradients. The growth timescale is much shorter than the dynamical time of structure formation. The coherence length of magnetic fields at the saturated time is much shorter than kpc scale and then, at nonlinear phase, become longer by inverse-cascade process. We report the application of our results to clusters of galaxies, not including hydrodynamic effects.

• 한국정밀공학회지
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• 제7권3호
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• pp.103-114
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• 1990

Many high speed mechanical systems incorporate gearing for speed reduction. This study investigates the stability of mulit-rotor geared systems supported on oil film bearings taking into consideration the coupling between torsional and lateral dynamics. The emphasis of the study is on the analysis of the interaction between the combined torsional and whirl insta- bilities. The feasility of inducing a lateral and the torsional instability to neutralize an anticipated unstable condition is investigated. The possibility of suppressing the instabilities by controlling the parameters of the oil film bearings is also considered.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.486-491
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• 1998

본 연구에서는 충돌면의 형상에 따른 고속 원형 충돌제트의 불안정 모드를 밝히기 위하여 우선 충돌면의 형상에 따른 주파수 특성을 비교하고자 하였다. 이를 위해 충돌면이 제트의 직경보다 작은 원판(small plate)과 제트의 직경보다 큰 구멍(hole)의 2가지 경우에 대하여 실험을 하였고, 평판 충돌음에 대한 연구결과와 비교 검토하였다.

• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.33-41
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• 2006

Theoretical-numerical approach of combustion instability in a specific rocket engine is conducted with parametric response functions. Fluctuating instantaneous burning rate is assumed to be functionally coupled with acoustic pressures and have a finite or time-varying amplitudes and phase lags. Only when the amplitudes and phases of combustion response function are sufficiently large and small respectively, the triggered unstable waves are amplified.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.53-54
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• 2012

In an IGCC plant, one of the most important issues on fuel flexibility in the lean premixed combustor is combustion instabilities. They are characterized by large amplitude pressure oscillations which are caused by unsteady heat release from the flames. The relationship between the unsteady heat release and flow oscillation can be qualitatively and quantitatively explained by flame transfer function. This paper introduces combustion instability modeling methods based on the flame transfer function approach.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1065-1070
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• 2007

The effects of hot carriers and self-heating on the electrical stability of p-channel TFTs have been analysed combining experimental data and numerical simulations. While hot carrier effects were shown not to induce appreciable degradation, self-heating related instability was found to more seriously affect the device characteristics. New models have been developed to explain the reported results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.268-269
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• 2003

The Boltzmann kinetic equation is solved directly by means of the conservative splitting method. Underexpanded supersonic free jet flows with small Knudsen numbers are studied. In this numerical simulation features intrinsic to appropriate experiments are observed. Streamwise vortices in a mixing layer and chaotic downstream temporal-spatial fluctuations of microscopic quantities with large amplitude are obtained.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.416-421
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• 2000

The performance of gas turbine engines is affected by instabilities, like as rotating stall and/or surge. Rotating Stall is a transient intermediate stage between normal flow and complete flow breakdown leading to engine surge. Rotating Stall is associated with large amplitude nonaxisymmetric flow variations rotating around the compressor annulus. This paper presents the evolutions of stall propagation in a compressor cascade by numerical analysis. The flow phenomena due to stall cells and propagation speed are examined using 2 dimensional Navier - Stokes equations.