• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.821-826
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• 2013

When the values of design variables change, mode switching can often occur. If the mode of interest is not tracked, the frequencies and modes for design optimization may be miscalculated owing to modes that differ from the intended ones. Thus, mode tracking must be employed to identify the frequencies and modes of interest whenever the values of design variables change during optimization. Furthermore, reliability-based design optimization (RBDO) must be performed for design problems with design variables containing uncertainty. In this research, we perform RBDO considering the mode tracking of a compressive coil spring, i.e., a component of the joint spring that supports a compressor, with design variables containing uncertainty by using only kriging metamodels based on multiple responses approach (MRA) without existing mode tracking methods. The reliability analyses for RBDO are employed using kriging metamodel-based Monte Carlo simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.840-845
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• 2005

This paper presents a robust optimal design method for a periodic structure type of MEMS resonator that is vulnerable to mode localization. The robust configuration of such a MEMS resonator to fabrication error is implemented by changing the regularity of periodic structure. For the mathematical convenience, the MEMS resonator is first modeled as a multi pendulum system. The index representing the measure of mode variation is then introduced using the perturbation method and the concept of modal assurance criterion. Finally, the optimal intentional mistuning, minimizing the expectation of the irregularity measure for each substructure, is determined for the normal distributed fabrication error and its robustness in the design of MEMS resonator to the fabrication error is demonstrated with numerical examples.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.931-938
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• 2005

This paper presents a robust optimal design method for a periodic structure type of MEMS resonator that is vulnerable to mode localization. The robust configuration of such a MEMS resonator to fabrication error is implemented by changing the regularity of periodic structure For the mathematical convenience, the MEMS resonator is first modeled as a multi-pendulum system. The index representing the measure of mode variation is then introduced using the perturbation method and the concept of modal assurance criterion. Finally, the optimal intentional mistuning, minimizing the expectation of the irregularity measure for each substructure, is determined for the normal distributed fabrication error and its robustness in the design of MEMS resonator to the fabrication error is demonstrated with numerical examples.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.7
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• pp.20-29
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• 1998

As the packing density of ICs in recent submicron IC design increases, interconnects gain importance. Because interconnects directly affect on two major components of circuit performance, power dissipation and operating speed, circuit engineers are concerned with the optimal design of interconnects and the aid tool to design them. When circuit models of interconnects are given (including geometry and material information), the analysis process for the given structure is not an easy task, but conversely, it is much more difficult to design an interconnect structure with given circuit characteristics. This paper focuses on the latter process that has not been foucsed on much till now due to the complexity of the problem, and prsents a design aid tool(DATOIS) to synthesize interconnects. this tool stroes the circuit performance parameters for normalized interconnect geometries, and has two oeprational modes:analysis mode and synthesis mode. In the analysis mode, circuit performance parameters are obtained by searching the internal database for a given geometry and interpolates results if necessary . In thesynthesis mode, when a given circuit performance parameter satisfies a set of geometry condition in the database, those geometry structures are printed out.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.216-217
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• 1999

A tapered ridge mode laser diode with increased spot size is designed and analyzed . The mode evolution concept is applied to design the taper and the method does not require regrowth or multiple-step etching technique. Three-dimensional BPM results show that the designed taper can transfer more than 97% of the mode power in the active region to the expanded mode.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.6-8
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• 2009

In this paper. we propose receiver algorithms for VHF(Very High Frequency) digital link mode-2(VDL Mode-2) systems. Unlike conventional digital communication systems using the root raised cosine filter as a transmit and receive filter, raised cosine filter is used as a transmit filter in VDL Mode-2 systems. Hence, it is crucial to design and implement the optimum lowpass receive filter by considering the amount of inter-symbol interference and noise performance. On the other hand, due to the short preamble pattern, it is crucial to develop an efficient packet detection algorithm for reliable communication link. In this paper, we design the optimum receive filter and packet detection algorithm and evaluate the performance of receiver adopting the proposed receive filter and packet detection algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.15-18
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• 2007

We consider the problem of designing a static output feedback sliding mode control law for linear dynamical systems with mismatched uncertainties in the state matrix. We assume that an output dependent sliding surface guaranteeing the quadratic stability of the sliding mode dynamics is given, the reachability condition is not required to be satisfied globally, and the output feedback sliding mode control law complises both linear and discontinuous parts. We reduce the problem of designing the linear part of the sliding mode control law to a simple LMI problem which offers design flexibility for combining various useful convex design specifications. Our approach does not require state transformation and it can be applied to mismatched uncertain systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1592-1594
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• 2009

This paper presents an LMI-based method to design a reduced order output feedback sliding mode controller for a class of uncertain systems. Using LMIs we derive an existence condition of a reduced order sliding mode control law. And we give explicit formulas of the gain matrices. Finally, we give a numerical design example, together with a design algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.1018-1021
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• 2006

This paper presents an LMI-based method to design sliding mode observers for a class of uncertain time-delay systems. Using LMIs we derive an existence condition of a sliding mode observer guaranteeing a stable sliding motion. And we give explicit formulas of the observer gain matrices. Finally, we give a simple LMI-based design algorithm, togeter with a numerical design example.

• Journal of Satellite, Information and Communications
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• v.8 no.3
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• pp.10-14
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• 2013

In this paper, when applying current-mode circuit design technique showing constant power dissipation none the less operation frequency, to the low power design of dynamic voltage frequency scaling, we introduce the low power current-mode circuit design technique applying MOSFET in sub-threshold region, in order to solve the problem that has large power dissipation especially on the condition of low operating frequency. BSIM 3, was used as a MOSFET model in circuit simulation. From the simulation result, the power dissipation of the current memory circuit with sub-threshold MOSFET showed $18.98{\mu}W$, which means the consumption reduction effect of 98%, compared with $900{\mu}W$ in that with strong inversion. It is confirmed that the proposed circuit design technique will be available in DVFS using a current-mode circuit design.