• Transactions of Materials Processing
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• v.12 no.3
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• pp.208-213
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• 2003

The methodology to design initial blanks considering the reduction of both springback and flange trimming amounts is studied. Three dimensional forming analysis of a trial blank Is first carried out using FEM and the tentative Initial blank shape is then determined by cutting the outer edge of the trial blank whose shape is nearly matched with the trimming line. During the shaping the blank edge, tile movement of blank outer line is described with random variables to reduce the sensitivity of initial blank geometry. After performing 2-D FEM forming and springback simulations for selected sections and optimizing the trimming and springback amounts in terms of section length of the blank, the initial blank is finally determined. In order to see tile springback reduction in the initial blank determined by the proposed method, a stepped s-rail is stamped and the sppingback is measured. The springback of newly designed initial blank of stopped s-tail is tremendously reduced.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.216-222
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• 1996

Since many typical 2.5 Gbps optical transmitter modules use a 50$\Omega$ characteristic impedance, they require relatively high voltage and high power sources compared to the 25$\Omega$ module. However, simple replacement of the 50$\Omega$ internal matching impedance with 25$\Omega$ results in bandwidth reduction and consequent problem of data transmitter module is proposed in order to expand the modulator bandwidth. From the calculated resutls based on accurate 3-dimensional inductance analysis, we have found that the series parasitic inductance is a dominant element limiting the bandwidth and the insertion of a 2.5pF capacitor in parallel to the 20$\Omega$ matching resiter can increase the 3 dB bandwidth about 1.4GHz wider. The time-domain results show the rise time (140 psec) without the compensation is greatly improved to 63 psec with the compensation. This capacitive ocmpensation can be implemented easily and be compatible with common manufacturing process of the optical transmitter module.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.630-634
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• 2016

We report the computer aided design results for a GaSb/InAs broken-gap gate all around nanowire tunneling FET (TFET). In designing, the semi-empirical tight-binding (TB) method using $sp3d5s^*$ is used as band structure model to produce the bulk properties. The calculated band structure is cooperated with open boundary conditions (OBCs) and a three-dimensional $Schr{\ddot{o}}dinger$-Poisson solver to execute quantum transport simulators. We find an device configuration for the operation voltage of 0.3 V which exhibit desired low sub-threshold swing (< 60 mV/dec) by adopting receded gate configuration while maintaining the high current characteristic ($I_{ON}$ > $100 {\mu}A/{\mu}m$) that broken-gap TFETs normally have.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.281-287
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• 2004

In this paper, the refined plastic-hinge analysis accounting for gradual yielding with fibers on a section is developed. Geometric nonlinearities of member(P-δ) and frame(P-Δ) are accounted for by using stability functions. Residual stresses are considered by assigning initial stresses to the fiber on the section. The elastic core in a section is investigated at every loading step to determine the axial and bending stiffness reduction. The strain reversal effect is captured by investigating the stress change of each fiber. The proposed analysis proves to be useful in applying for practical analysis and design of three-dimensional steel frames.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.880-882
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• 1999

Virtual Reality is a set of computer technologies which, when combined, provide an interface to a computer-generated world, and in particular, provide such a convincing interface that the user believes he is actually in a three dimensional computer-generated world. This computer generated world may be a model of a real-world object, such as a house; it might be an world that does not exist in a real sense but is understood by humans, such as a chemical molecule or a representation of a set of data; or it might be in a completely imaginary science fiction world. this paper describes the application of boiler digital control system MMI for power plant using virtual reality

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.404-407
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• 1992

In this thesis, the algorithm of Fuzzy Logic Control(FLC) is applied to the Nonlinear system to implement a system response. Proportional-Integral-Derivative(PID) controller is also used to control the various systems. Look-up table is applied to decide the control input, and the other look-up table is added for saving memories and inference time. Generally, FLC input variables are error(E) and error derivative($\Delta$E). In this algorithm. another Input variable error's second derivative($\Delta^2$E) is added for Robust Fine control.

• The KSFM Journal of Fluid Machinery
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• v.9 no.3 s.36
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• pp.7-13
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• 2006

Shape optimization of a rotor blade in a single-stage transonic axial compressor has been performed using a response surface method and three-dimensional Navier-Stokes analysis. Two shape variables of the rotor blade, which are used to define a blade skew, are introduced to increase an adiabatic efficiency. Throughout the shape optimization of a rotor blade, the adiabatic efficiency is increased to about 2.2 percent compared to that of the reference shape of the stator. The increase in efficiency for the optimal shape of the rotor is due to the pressure enhancement, which is mainly caused by moving the separation position on the suction surface of rotor blade to the downstream direction.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.101.3-101
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• 2001

By setting a refractor with a certain angle against the optical axis of the CCD camera lens, the image of a measuring point recorded on the image plane is displaced by the corresponding amounts related to the distance between the camera and the measuring point. When the refractor that keeps the angle against the optical axis is rotated physically at high speed during the exposure of the camera, the image of a measuring point draws an annular streak. Since the size of the annular streak is inversely proportional to the distance between the camera and the measuring point, the 3D position of the measuring point can be obtained by processing the streak. In this paper, for one of the applications of our system, the measurement of a moving surface is introduced. In order to measure the moving surface, multi laser spots are projected on the surface of object. Each position of ...

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.561-565
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• 1988

In the present study, a new method of generating a nearly orthogonal boundary-fitted coordinate systems with automatic grid spacing control is introduced. Applications of the method to a two dimensional simply-connected region is then demonstrated. The nearly orthogonal boundary-fitted method has the following features, (a) Strong grid control in the .eta.-direction can be made, (b) The generated boundary-fitted coordinates are nearly orthoronal, (c) Both the .xi.-and .eta.-direction control function are mathematically derived. Especially the .eta.-direction control function is derived under the assumption that the .eta.-direction grid spacing is by far smaller than the .xi.-direction grid spacing when the .eta.-direction grid line is strongly clustered. (d) The grid control functions are dynamically adjusted by the metric scale factors imposed on the boundary. The control function is fully automatic and eliminates the need of user manipulation of the control function.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.925-928
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• 2003

In this paper, a precision measuring machine for large sized axial fans of cooling towers are developed. A laser sensor is used as a measuring device and aluminum profiles and stepping motors are engaged into the system as frame structure and driving devices respectively. 3-dimensional measuring data are compared to the design data to compute the distortion of the axial fans. Two distortions such as the axis of the fan and the airfoils along the axis are introduced to define the shape precision of axial fans. Genetic algorithm is used to solve the optimization problem during computing the distortion. Results of distortion are displayed 3 dimensionally in a solid-modeler as well as 2-D drawings to help users find it with case.