• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.237-243
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• 2011

Thermal characteristics, such as diffusivity and temperature induced change in the fiber mode index of rotation sensing fiber coil are critical factors which determine the time varying, thermo-optically induced bias drift of interferometric fiber-optic gyroscopes (IFOGs). In this study, temperature dependence of the transient effect is analyzed in terms of the thermal characteristics of the fiber coil at three different temperatures. By applying an analytic model to the measured bias in the experiments, comprehensive thermal factors of the fiber coil could be extracted effectively. The validity of the model was confirmed by the fact that the extracted values are reasonable results in comparison with well known properties of the materials of the fiber coil. Temperature induced changes in the critical factors were confirmed to be essential in compensating the transient effect over a wide temperature range.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.5
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• pp.263-267
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• 2016

In this paper, we analyzed the electrical characteristics of NPT planar and trench gate IGBT after designing these devices according to design and process parameter. To begin with, we have designed NPT planar gate IGBT and carried out simulation with T-CAD. Therefore, we extracted design and process parameter and obtained optimal electrical characteristics. The breakdown voltage was 724 V and The on state voltage drop was 1.746 V. The next was carried out optimal design of trench gate power IGBT. We did this research by same drift thickness and resistivity of planar gate power IGBT. As a result of experiment, we obtain 720 V breakdown voltage, 1.32 V on state voltage drop and 4.077 V threshold voltage. These results were improved performance and fabrication of trench gate power IGBT and planar gate Power IGBT.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.938-940
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• 1999

We have fabricated SiC Schottky diode for high temperature applications. SiC thin film for drift region has been deposited by ICP-CVD. In order to establish metallization conditions, we have extracted the device parameters of the Schottky diode from the forward I-V characteristics and the C-V characteristics as a function of temperature. The ideality factor was varied from 2.07 to 1.15 and the barrier height was also varied from 1.26eV to 1.92eV with increase of temperature. The reverse blocking voltage was 183 V.

• International Journal of Ocean System Engineering
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• v.1 no.3
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• pp.155-164
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• 2011

The second-order motion characteristics of a semi-submersible are investigated in regular waves. A higher-order boundary element method in a frequency domain and a finite element method in a time-domain were applied to the numerical analysis of the nonlinear hydrodynamic force and motion characteristics of semi-submersibles in view point of potential flow. Various aspects of nonlinear effects on the heave and roll of a semi-submersible were numerically investigated and some selected cases were compared with the model test data.

• Electrical & Electronic Materials
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• v.9 no.7
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• pp.660-667
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• 1996

The electron transport characteristics in $SF_6$ gas is calculated for range of E/N values from 150 -800(Td) by the Monte Carlo simulation using a set of electron collision cross sections determined by the authors. The results suggest that the value of an electron swarm parameter such as the electron drift velocity, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients in nearly agreement with the respective experimental and theoretical for a range of E/N. The electron energy distributions function were analysed in sulphur hexaflouride at E/N:500 and 800(Td) for a case of the equilibrium region in the mean electron energy. The validity of the results obtained has been confirmed by a Time of Flight method also investigated as a set of electron collision cross section for sulphur Hexaflouride.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.838-845
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• 2009

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models are reviewed. Three earthquake records of El-centre, Santa-Monica, Taft and three artificial earthquake records in accordance with Korea standard are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with various hysteresis models. As results, story shear force is increased by maximum 60% according to hysteresis model. And Story drift ratio is increased by maximum 42% according to hysteresis model. And The result with clough model shows the maximum hinge distribution state.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.190-193
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• 2010

Various power semiconductor devices have been developed and evolved since 1950s. Among them, IGBT is the most developed power semiconductor device which has high breakdown voltage, high current conduction and suitable switching speed which perform trade-offs between each other. In other words, there are trade-offs between a breakdown voltage and on-state voltage drop, and between on-state voltage drop and turn-off time. In this paper, the new structure is proposed to improve a trade-off between a breakdown voltage and on-state voltage drop. The proposed structure has a trench collector and this trench collector induces an accumulation layer at the bottom of an n-drift region during off-state. And this accumulation layer prevents expansion of depletion layer so that trapezoidal electric field distribution is performed in the n-drift region. As a result of this, breakdown voltage is increased without increasing on-state voltage drop. The electrical characteristics of the proposed IGBT is analyzed and optimized by using representative device simulator, TSUPREM4 and MEDICI. After optimization, the electrical characteristics of the proposed IGBT is compared with NPT IGBT which have the same device thickness. As a result of this, it can be confirmed that the proposed structure increases the breakdown voltage of 800 V than that of the conventional NPT IGBT without increasing the on-state voltage drop.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.41-46
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• 1996

The Pd/Pt gate MISFET type hydrogen sensors, for detecting dissolved hydrogen gas in the transformer oil, were fabricated and their characteristics were investigated. These sensors including diffused resister heater and temperature monitoring diode were fabricated on the same chip by a conventional silicon process technique. The differential pair plays a role in minimizing the intrinsic voltage drift of the MISFET. To avoid the drift of the sensors induced by the hydrogen, the gate insulators of both FETs were constructed with double layers of silicon dioxide and silicon nitride. In order to eliminate the blister formation on the surface of the hydrogen sensing gate metal, Pt and Pd double metal layers were deposited on the gate insulator. The hydrogen response of the Pd/Pt gate MISFET suggests that the proposed sensor can detect the dissolved hydrogen in transformer oil with 40mV/10ppm of sensitivity and 0.14mV/day of stability.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.1
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• pp.48-61
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• 1989

In this paper, two-dimensional numerical simulation of GaAs MESFFT with 0.7${\mu}m$ gate length is perfomed. Drift-diffusion model which consider that mobility is a function of local electric field, is used. As a discretization method, instead of FDM (finite difference method) and FEM (finite element method), the Control-Volume Formulation (CVF) is used and as a numerical scheme current hybrid scheme or upwind scheme is replaced by power-law scheme which is very approximate to exponential scheme. In the process of numerical analysis, Peclet number which represents the velocity ratio of drift and diffusion, is introduced. And using this concept a current equation which consider numerical scheme at the interface of control volume, is proposed. The I-V characteristics using the model and numerical method has a good agreement with that of previous paper by others. Therefore, it is confined that it may be useful as a simulator for GaAs MESFET. Besides I-V characteristics, the mechanism of both velocity saturation in drift-diffusion model is described from the view of velocity and electric field distribution at the bottom of the channel. In addition, the relationship between the mechanism and position of dipole and drain current, are described.

• Journal of computational fluids engineering
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• v.12 no.1
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• pp.16-21
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• 2007

This paper presents numerical results of fluid flows and mixing in a microfluidic device with AC electroosmotic flows (AC-EOF) around coplanar electrodes attached on the top and bottom walls. To obtain the flow and mixing characteristics, numerical computations are performed by using a commercial code, CFX10. Experiment was performed to confirm the generation of the drift velocity around the electrodes. It was found that near the coplanar electrodes 3-D complex flows are generated. The AC-electroosmotic flow on the electrodes plays an important role in mixing the liquid.