• 호남수학학술지
• /
• 제36권1호
• /
• pp.141-146
• /
• 2014

In this paper, we obtain a necessary and sufficient condition for the second variation of an arbitrarily given smooth variation of a geodesic on a Riemannian manifold to be 0.

• 대한전기학회논문지
• /
• 제35권7호
• /
• pp.278-284
• /
• 1986

Double-diffused metal oxide power semiconductor field effect transistors are used extensively in recent years in various circuit applications. The temperature variation of the drain current at a fixed bias shows both positive and negative resistance characteristics depending on the gate threshold voltage and gate-to source bias votage. In this paper, the decision method of the gate crossover voltage by the temperature variation and a new method to determine the gate threshold voltage graphecally are presented.

• Journal of information and communication convergence engineering
• /
• 제7권1호
• /
• pp.57-61
• /
• 2009

This paper has presented the subthreshold current model of FinFET using the potential variation in the doped channel based on the analytical solution of three dimensional Poisson's equation. The model has been verified by the comparison with the data from 3D numerical device simulator. The variation of subthreshold current with front and back gate bias has been studied. The variation of subthreshold swing and threshold voltage with front and back gate bias has been investigated.

• 대한전기학회논문지
• /
• 제39권5호
• /
• pp.516-518
• /
• 1990

We have derived the equation which involves the variation of electron energy with time in a lowly ionized plasma when a low alternating electric field is applied. We consider only elastic collisions between electrons and neutral atoms. This equation is solved using the 4th-order Runge-Kutta method, and applied to argon gas discharge which is driven by source frequency of 100, 1K, 10K, 100K, and 1M (Hz). The results show that the variation of electron energy becomes flat with higher frequencies.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2005년도 추계 학술대회논문집
• /
• pp.27-30
• /
• 2005

In a microfluidic chips pressure driven flow or electro-osmotic flow has been usually employed to deliver bio-samples. Flow in the chips is usually slow and the mixing performance is poor. A micro-mixer with a rapid mixing is important for practical applications. In this study a newly designed and electro-osmotic driven micro-mixer is proposed. This design is comprised of a channel and a series of metal electrodes periodically attached on the side surface. In this configuration electro-osmotic flows and the stirring effects are simulated three-dimensionally using a commercial code, CFD-ACE. Focus is given the effect on the electro-osmotic flow characteristics under the local variation of the electric field.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2011년도 임시총회 및 하계학술연구발표회
• /
• pp.93-95
• /
• 2011

In this study we tried to measure the effect of magnetic field on the dielectric properties of $BaTiO_3-MgFe_2O_4$ soft magnetic composite. Composites with different weight percents of ferroelectric and ferromagnetic phases were subjected to magnetic field in the order of 0 to 450 Oe and the variation of the dielectric properties was observed. The Variation of dielectric polarization was discussed in terms of Maxwell-Wagner type polarization in particulate composites.

• E2M - 전기 전자와 첨단 소재
• /
• 제10권9호
• /
• pp.945-951
• /
• 1997

Inorder to investigated electrical conduction characteristics of silicone oils due to viscosity variation we studied the electrical conduction properties at temperature range of 10~110[$^{\circ}C$] and electrical field from 1 to 1.33$\times$10$^4$[V/cm] The viscosity of used specimens was low viscous(1, 2, 5[cSt]) silicone oils. It was shown the ohmic conduction characteristics in low temperature and low field by Ion dipole and humidity included specimen. And we known the conduction mechanism due to electron injection by Schottky's effect in the high temperature an d high field region.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.374-378
• /
• 2003

This paper presents investigation of damping characteristics of squeeze mode type MR (Magneto-Rheological) mount experimentally. Since damping property of the MR fluid is changed by variation of the applied magnetic field strength, squeeze mode type MR mount proposed in the study has variable damping characteristics according to the applied magnetic field s strength. In the present work, the performance of the mount was experimentally investigated according to the magnetic field strength and exciting frequencies. The experimental results present that the MR mount can effectively reduce the vibration in a wide range of frequency by controlling the applied electromagnetic filed strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents in this study and MR effect is reduced by increasing exciting frequency.

• 한국해양공학회지
• /
• 제16권2호
• /
• pp.27-31
• /
• 2002

The purpose of this study is to investigate the variation of resonance that is possible caused by construction of new port in a practical sea area between the existing port and the new one. The research of amplification that of the sea area was accomplished for the variation of resonance. In this study, long period wave that is observed continuously in the practical sea area was analyzed, and then secondary undulation was reproduced by numerical analysis. As a result of numerical analysis, the first mode resonant periods in the existing port is 640sec, and in the new one is 500sec. On the other hand, we know there is long period wave of 500sec from analyzation of field datas. Because that period this period is the resonant period in the new port. There is also the possibility of secondary undulation cause of resonant.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 봄 학술발표회 논문집
• /
• pp.509-516
• /
• 2002

Rainfall-induced landslides in a weathered granite soil slope have mostly relative shallow slip surfaces above the groundwater table The pore-water pressure of soil above the groundwater table is usually negative. This negative pore-water pressure(or matric suction) has been found to make a large contribution to the slope stability. Therefore, the variation of in-situ matric suction profiles with time in a soil slope should be understood. In this study, a field measurement program was carried out from June to August, 2001 to monitor in-situ matric suctions and volumetric water contents in a weathered granite soil slope. The influence of climatic conditions on the variation of in-situ matric suctions could be found to decrease rapidly with depth. It could be found that decrement of matric suction induced by precipitation is affected not only by the amount and duration of rainfalls but also by the initial matric suction just prior to rainstorms. The soil-water characteristic from the field monitoring tends toward the wetting path of SWCC obtained from the laboratory test.