• Tribology and Lubricants
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• v.14 no.1
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• pp.85-93
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• 1998

The Bair & Winer's limiting shear stress rheological model is incorporated into the Reynolds equation to successfully predict the traction and film thickness for an isothermal line contact using the primary rheological properties. The modified WLF viscosity model and Barus viscosity model are also adapted for the realistic prediction of EHD tractional behavior. The influences of the limiting shear stress and slide-roll ratio on the pressure spike, film thickness, distribution of shear stress and nonlinear variation of traction are examined. A good agreement between the disc machine experiments and numerical traction prediction has been established. The film thickness due to non-Newtonian effects does not deviate significantly from the fdm thicknesss with Newtonian lubricant.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1337-1339
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• 1998

The trench termination scheme is introduced for high voltage devices. The curvature of the depletion region at field limiting ring is critical factor to determine the breakdown voltage. The smooth curvature of the depletion junction alleviate the electric field crowding effect around this region. In the trench field limiting ring, the radius of the depletion region is smaller than conventional field limiting ring, but the distance between every trench is spaced small enough to punchthrough before initiation of local breakdown. The trench field limiting ring on silicon can ne formed by RIE followed by oxidation on side wall surface of the trench, and polysilicon filling. The combined termination of this trench floating field ring and field plate have been designed and analyzed. The breakdown simulation by 2-dimensional TCAD shows that the cylindrical junction breakdown voltage for substrate doping might be 99 percent of the ideal breakdwon voltage for substrate doping concentration of $3\times10^{14}cm^{-3}$ with about $100{\mu}m$ of lateral termination width.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.404-411
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• 2010

The present paper deals with the continuous work of extending multi-dimensional limiting process (MLP), which has been quite successfully proposed on two- and three-dimensional structured grids, onto the unstructured grids. The basic idea of the present limiting strategy is to control the distribution of both cell-centered and cell-vertex physical properties to mimic a multi-dimensional nature of flow physics, which can be formulated as so called the MLP condition. The MLP condition can guarantee a high-order spatial accuracy without yielding spurious oscillations. Recently, MLP slope limiter was proposed based on the MUSCL-type reconstruction in two-dimensional case and it can be readily extended to three-dimensional case. Through various numerical analyses and extensive computations, it is observed that the proposed limiters are quite effective in controlling numerical oscillations and very accurate in capturing both discontinuous and continuous multi-dimensional flow features on 3-D tetrahedral grids.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.685-690
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• 2000

In this study relationship between relief angles and chatter vibration in turning was examined by using the direct cutting test, in which the cutting depth of a tapered workpiece is varied continuously and the limiting depth of cut is measured at the time when chatter occurs. Test results reveal that 1) limiting depth of cut increases is proportion to side relief angles between 0$^{\circ}$ and 3$^{\circ}$, 2) limiting depth of cut does not show any evident change in spite of side relief angle increased from 3$^{\circ}$ to 12$^{\circ}$, 3) also limiting depth of cut does not change despite front angle change from 0$^{\circ}$ to 12$^{\circ}$.

• Progress in Superconductivity
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• v.12 no.1
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• pp.23-26
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• 2010

A double line commutation (DLC) type SFCL with first peak limiting function has been proposed for ideal fault current limiting operation. Very fast switching (commutation) without any arc or high voltage problems for any kind of switching device is needed for the first peak current limiting. We've tried to find suitable conditions for a successful switching of a Vacuum Interrupter (VI) with HTS elements as a Peak Current limiting Resistance (PCR).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.499-504
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• 2016

In this paper, we analyzed the operational characteristics of the fault current limiting according to the amplitude of the fault current for the transformer type superconducting fault current limiter (SFCL). If the fault current happens, the superconducting element connected to the secondary coil is occurred quench and the fault current is limited. When the larger fault current occurs, the superconducting element connected to the third coil is occurred additional quench and the peak fault current is limited. We found that the fault current can be more effectively controlled through the analysis of the fault current limiting and the short-circuit tests.

• Structural Engineering and Mechanics
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• v.38 no.6
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• pp.825-847
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• 2011

This paper investigates the design using wind-moment method for semi-rigid un-braced steel frames bending on weak axis. A limiting sway method has been proposed to reduce the frame sway. Allowance for steel section optimization between moment of inertia on minor axis column and major axis beam was used in conjunction with slope-deflection analysis to derive equations for optimum design in the proposed method. A series of un-braced steel frames comprised of two, four, and six bays ranging in height of two and four storey were studied on minor axis framing. The frames were designed for minimum gravity load in conjunction with maximum wind load and vice-versa. The accuracy of the design equation was found to be in good agreement with linear elastic computer analysis up to second order analysis. The study concluded that the adoption of wind-moment method and the proposed limiting sway method for semi-rigid steel frame bending on weak axis should be restricted to low-rise frames not more than four storey.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1451-1453
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• 1994

A monolithic current limiting power MOSFET, which may be easily fabricated by the conventional DMOS process, is proposed. The proposed current limiting MOSFET consists of main power cells, sensing cells, and NPN lateral bipolar transistor so that users can adjust the current limiting levels with only one external resistor. The behaviors of the proposed device are numerically simulated and analyzed by 2-D device simulator MEDICI and mixed-mode simulator CA-AAM(Circuit Analysis Advanced Application Module).

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.281-283
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• 2008

The superconducting fault current limiter (SFCL) using magnetic coupling of two coils with series connection, which was suggested by us, has the merit to increase the operational current and the limiting impedance of the SFCL through the adjustment of the inductance ratio and the winding direction of two coils. In addition, the recovery characteristics of the SFCL is affected by the winding direction of two coils as well as two coils' inductance ratio. In this paper, the fault current limiting and recovery characteristics of a SFCL using magnetic coupling of two coils with series connection were analyzed. Through the analysis based on the experimental results, the recovery characteristics and the current limiting characteristics of the SFCL were confirmed to be improved more in case of the additive polarity winding.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.418-420
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• 2003

The fault current limiting characteristics at the initial fault time for flux-lock type high-Tc superconducting fault current limiter(SFCL) were investigated. The amplitude of initial fault current of the flux-lock type SFCL was dependent on the inductance ratio of coil 1 and 2. After fault current limiting mode was analyzed, we compared the calculated value with the experimental one for the initial fault current. The effect of initial fault current due to the inductance ratio of coil 1 and 2 on fault current limiting characteristics was discussed.