• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.3
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• pp.267-273
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• 1992

An advanced on-resistance model of VDMOS devices in the low voltage regimes is proposed and verified by 2-D device simulations. The model considers the lateral gaussian doping profiles in the channel region and exact current spreading angles in the epitaxial layer for both linear and cellular geometries by employing the conformal mapping, It is found out that the on-resistance of low voltage VDMOS may be overestimated considerably if it is analyzed by the conventional method. The 2-D device simulation results show that the proposed model is valid for the VDMOS devices in the low voltage regimes.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1349-1351
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• 1997

TFT2DS was utilized to provide the usefulness as an analytic and design tool. In this paper, the general effects of channel length of an inverted staggered amorphous silicon thin film transistor on its characteristics were investigated. The results obtained from these experiments would be adopted to the optimized device designs and advanced simulations of their electrical properties.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.666-674
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• 2021

A selective catalyst reduction system (SCR) with an integrated bypass unit is proposed. Through simulations of the SCR, variations in flow to the catalyst due to the particular shape of the bypass shutting device in the SCR are also studied. The commercial software Ansys Fluent is used to develop the simulations. For the simulations, the catalyst of the SCR is modeled using the porous media method to reduce the calculation time and number of meshes, which is necessary because of the detailed modeling of the catalyst. Simulations are performed based on changes to the entrance angle to the catalyst and the size of the bypass shutting device. Finally, simulation results are used to compare and analyze the average velocity and uniformity of the flow to the catalyst.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.1
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• pp.23-31
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• 2006

The present works concerns a side flushing device for the improvement of the conventional Electric-Discharge Machining(EDM) process. In the EDM process, chips are usually generated as the workpiece is removed, and deposited between the electrode and the workpiece. This sediment degrades the surface finish of the machined product as well as the processing efficiency. In the present study, a flushing device with additional side injection equipments is proposed in order to remove the deposited chips effectively. Through numerical simulations, the validity of the proposed device is verified, and the influence of process parameters is investigated. Experiments have been also carried out in the die sinking EDM process. It was observed that the process efficiency and the surface finish are improved by virtue of the proposed flushing device.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.1
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• pp.9-15
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• 2012

This paper shows an effective scanning trajectory for a mine detection device that is one of the mission equipments of unmanned ground vehicle. The mine detection device is composed of a mine-detection sensor, and a 4 DOF manipulator enabling sensor position control. There are three modes that manage the mine detection device: passive, semi-automatic, and automatic. The automatic mode is used the most. This paper suggests a scanning method that makes shape of 8. This method prevents missing target area and enhances scanning speed when the mine detection device scans the ground surface in automatic mode. The suggested method is verified by simulations and experiments.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.107-112
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• 2011

This paper is for improving the RF frequency performance of a fabricated 100nm ${\Gamma}$-gate MHEMT, scaling down vertically for the epitaxy-structure layers of the device. Hydrodynamic simulation parameters are calibrated for the fabricated MHEMT with the modulation-doped $In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}$As heterostructure grown on the GaAs substrate. With these calibrated parameters, simulations for the vertically-scaled epitaxial layers of the device are performed and analyzed for DC/RF characteristics, including the quantization effect due to the thickness reduction of InGaAs channel layer. A newly designed epitaxy-structure device shows higher extrinsic transconductance, $g_m$ of 1.556 S/mm, and higher frequency performance, $f_T$ of 222.5 GHz and $f_{max}$ of 849.6 GHz.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.61-66
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• 2010

Pay off reel is the device to release in the form of coil. Every time the device becomes a hassle to exchange, each diameter of two forms has been applied to the coil reel. There is the change of reel diameter of the sleeve portion to be the part of segment geometry. This unit is conducting on 3-dimensional modeling design. The basic strength and deformation of the device could be checked in advance by the basis of 3-d modeling data to perform simulations. The production of each part can be completed and assembled. Conducted for the final product which is tested and measured, all items are satisfied within the limits of targets. Due to the development of this device, the efficiency on operations can be increased and the production time becomes shortened.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1615-1620
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• 2003

Kinematic calibration is a process whereby the actual values of geometric parameters are estimated so as to minimize the error in absolute positioning. Measuring all components of Cartesian posture, particularly the orientation, can be difficult. With partial pose measurements, all parameters may not be identifiable. This paper proposes a new device that can identify all kinematic parameters with partial pose measurements. Study is performed for a six degree-of-freedom fully parallel Hexa Slide manipulator. The device, however, is general and can be used for other parallel manipulators. The proposed device consists of a link with U joints on both sides and is equipped with a rotary sensor and a biaxial inclinometer. When attached between the base and the mobile platform, the device restricts the end-effector's motion to five degree-of-freedom and can measure position of the end-effector and one of its rotations. Numerical analyses of the identification Jacobian reveal that all parameters are identifiable. Computer simulations show that the identification is robust for the errors in the initial guess and the measurement noise. Intrinsic inaccuracies of the device can significantly deteriorate the calibration results. A measurement procedure is proposed and formulations of cost functions are discussed to prevent propagation of the inaccuracies to the calibration results.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.175-180
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• 2015

Worldwide, studies on intelligent vehicles for the convenience of drivers have been actively conducted as the number of cars has increased. However, vehicle convenience enabled by buttons lowers the concentration on driving and hence poses as a huge threat to the safety of the driver. The use of one of the convenient features, impaired driving auxiliary equipment, is limited because of its complex usage, and this device also hinders the front view of the driver. This paper proposes a vehicle-control device for controlling the convenient features as well as changes in speed and direction using gestures and motions of the driver. This device consists of an ultrasonic sensor for recognizing movement, an arduino for accepting signal control functions and servo and DC motors apply to various vehicle parts. Firstly, the vehicle-control device was designed using a 3D CAD program known as Solid-works based on the size of the steering wheel. Then, through simulations, a suitable length for minimizing the absorbent between ultrasonic sensors was confirmed using a program known as COMSOL Multiphysics. Finally, simulation results were verified through experiments, and the optimal size of the device was identified through the number of errors.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.305-306
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• 2009

This paper shows through detailed simulations that the length of conventionally designed multimode-interference couplers can be shorted significantly by stepped-width and stepped-index design. For the cross-coupling device, this stepped-design results in 9% or more length reduction.