• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.615-623
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• 2008

This paper proposes an $H_{\infty}$ controller design method for Takagi-Sugeno (T-S) fuzzy systems using a fuzzy basis-function-dependent Lyapunov function. Sufficient conditions for the guaranteed $H_{\infty}$ performance of the T-S fuzzy control system are given in terms of linear matrix inequalities (LMIs). These LMI conditions are further used for a convex optimization problem in which the $H_{\infty}-norm$ of the closed-loop system is to be minimized. To facilitate the basis-function-dependent Lyapunov function approach and thus improve the closed-loop system performance, additional decision variables are introduced in the optimization problem, which provide an additional degree-of-freedom and thus can enlarge the solution space of the problem. Numerical examples show the effectiveness of the proposed method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.223-229
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• 1996

a simpel coordinate transformaton method is suggested that converts Schr$\"{o}$dinger's equation involving a position-dependent effective mass in a heterostructure to an equation involving a positon-independent effective mass. This method enables the conceptual study of the effect of the positon-dependent effective mass inserted between the divergence operator and the gradient operator in Schr$\"{o}$dinger's equation. It is also shown that the characteristics such as a transmission coefficient in various heterostructures involving a position-dependent effective masses can be obtained iwth ease by the suggested method.

• Transactions of Materials Processing
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• v.24 no.5
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• pp.361-367
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• 2015

The forming limit diagram (FLD) is the most commonly used tool for evaluating of sheet metal formability in the manufacturing field as well as the finite element analysis (FEA)-based design process. Determination of the forming limits is considerably influenced by testing/measuring machines, techniques and conditions. These influences may cause a large scatter in FLD from laboratory to laboratory. Scatter is especially true when the ‘position-dependent method’, as is specified in most national and international standards, is used. In the current study a new ‘time-dependent method’ is proposed, which is to determine the forming limit strains more accurately and reasonably when producing a FLD from experimental data. This method is based on continual strain measurement during the test. The results are compared to those from the existing standardized methods.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.3
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• pp.154-159
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• 2015

In this paper, we propose a numerical method to model temperature dependent threshold voltage shift observed in metal oxide thin-film transistors (TFTs). The proposed model is then implemented in AIM-SPICE circuit simulation tool. The proposed method consists of modeling the well-known stretched-exponential time dependent threshold voltage shift and their temperature dependent coefficients. The outputs from AIM-SPICE tool and the stretched-exponential model at different temperatures in the literature are compared and they show a good agreement. Since metal oxide TFTs are the promising candidate for flat panel displays, the proposed method will be a good stepping stone to help enhance reliability of fast-evolving display circuits.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.99.2-99.2
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• 2012

혜성에서 방출되는 CH 분자는 핵에서 방출되어 태양 빛에 의해 분해되는 시간인 lifetime이 짧다. Lifetime이 짧은 분자는 모든 energy state로의 천이가 충분히 일어나 안정된 상태인 fluorescent equilibrium상태에 도달하기 전에 분해되어 버리기 때문에 혜성 속의CH의 특성을 파악하기 위해서는 Time-dependent calculation이 꼭 필요하다. Time-dependent calculation 은 CH 분자가 핵에서 방출된 후 시간에 따라 변하는population을 계산함으로써 각 혜성의 조건에 알맞은 CH model을 얻을 수 있어 혜성에서 방출되는 분자들을 연구하기에 적합한 방법이다. 우리는 BOES로 관측한 Machholz(C/2004 Q2), 103P/Hartley혜성을 포함한 Hyakutake (C/1996 B2)혜성과 Austin (1990V)혜성의 고분산 분광자료를 이용하여 Time-dependent calculation 을 실시하였고, 그 결과를 소개하고자 한다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1329-1333
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• 2006

This paper proposes a framework for product development including hardware and software components. The framework provides separation of the hardware dependent software, an integrated product development process, and integration of software components with product configurations and product structures. In order to separates the hardware dependent software, the framework considers product configuration modules and engineering changes of associated hardware and software components. The proposed product development process integrates development of the hardware dependent software into the existing product development process. In order to integrates the hardware dependent software with product configurations and product structures, the framework represents software components by existing product data models in Product Data Management (PDM). The framework is applied to development of a robot system including hardware and software components in order to show its effectiveness.

• BMB Reports
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• v.28 no.1
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• pp.27-32
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• 1995

Polyclonal antibodies against human DNA-dependent RNA polymerase II (HPP II) were generated from chicken egg yolk after immunization with RNA polymerase II as an antigen. The antibodies from egg yolk (IgY) were purified and characterized. IgY showed a specificity against DNA-dependent RNA polymerase II, and was a polyclonal antibody against 12 subunits of polymerase II. An amount of 0.35 mg of IgY was obtained freman HPP II-Sepharose affinity column using 10 eggs from a chicken immunized against RNA polymerase II as an antigen. These antibodies can be used for isolating the genes for RNA polymerase II components, and for in vitro transcription assays using HP-RNA polymerase II.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.4
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• pp.495-503
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• 2000

The present numerical study investigates flow characteristics and heat transfer enhancement of the viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. The combined effect of temperature-dependent viscosity, buoyancy and secondary flow caused by second normal stress difference are all considered. The Reiner-Rivlin model is used as a viscoelastic fluid model to simulate the secondary flow and temperature-dependent viscosity model is adopted. Three types of thermal boundary conditions involving different combinations of heated walls and adiabatic walls are considered in this study. Calculated Nusselt numbers are in good agreement with experimental results in both the thermal developing and thermally developed regions. The heat transfer enhancement can be explained by the combined viscoelasticity-driven secondary flow, buoyancy-induced secondary flow and temperature-dependent viscosity.

• Structural Engineering and Mechanics
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• v.60 no.1
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• pp.149-162
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• 2016

Structure-dependent integration methods seem promising for structural dynamics applications since they can integrate unconditional stability and explicit formulation together, which can enable the integration methods to save many computational efforts when compared to an implicit method. A newly developed structure-dependent integration method can inherit such numerical properties. However, an unusual overshooting behavior might be experienced as it is used to compute a forced vibration response. The root cause of this inaccuracy is thoroughly explored herein. In addition, a scheme is proposed to modify this family method to overcome this unusual overshooting behavior. In fact, two improved formulations are proposed by adjusting the difference equations. As a result, it is verified that the two improved formulations of the integration methods can effectively overcome the difficulty arising from the inaccurate integration of the steady-state response of a high frequency mode.

• Structural Engineering and Mechanics
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• v.61 no.3
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• pp.317-323
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• 2017

This work presents a new strategy to model stress dependent relaxation process in large deformation. The strategy is relied on the fact that in some particular soft materials undergoing large deformation, e.g., elastomers, rubbers and soft tissues, the relaxation time depends strongly on stress levels. To simplify the viscoelastic model, we consider that the relaxation time is the function of previous elastic deviatoric stress state experienced by materials during loading. Using the General Maxwell Model (GMM), we simulate numerically conditions with the constant and the stress dependent relaxation time for uniaxial tension and compression loading. Hence, it can be shown that the proposed model herein not only can represent different relaxation time for different stress level but also maintain the capability of the GMM to model hysteresis phenomena.