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Kim, Daewook The Youngnam Mathematical Society 2016 East Asian mathematical journal Vol.32 No.3
In this paper, we study the viscoelastic Kirchhoff type equation with the following nonlinear source and time-varying delay $$u_{tt}-M(x,t,{\parallel}{\nabla}u(t){\parallel}^2){\Delta}u+{\int_{0}^{t}}h(t-{\tau})div[a(x){\nabla}u({\tau})]d{\tau}\\+{\parallel}u{\parallel}^{\gamma}u+{\mu}_1u_t(x,t)+{\mu}_2u_t(x,t-s(t))=0.$$ Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.
Kim, Daewook The Youngnam Mathematical Society 2018 East Asian mathematical journal Vol.34 No.1
In this paper, we study the viscoelastic Kirchhoff type equation with a nonlinear source for each independent kernels h and g with respect to Volterra terms. Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.
Some Boundary Feedback Control of a Nonlinear String Equation of Kirchhoff-Carrier Type
Daewook Kim,Il Hyo Jung 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
In this paper we study the boundary control for Nonlinear problem concerning the hyperbolic equation suggested in the study of the viscoelastic string model of Kirchhoff-Carrier type. We also give some numerical simulation for each suggested boundary conditions by feedback control.
STABILIZATION FOR THE VISCOELASTIC KIRCHHOFF TYPE EQUATION WITH A NONLINEAR SOURCE
Kim, Daewook The Youngnam Mathematical Society 2016 East Asian mathematical journal Vol.32 No.1
In this paper, we study the viscoelastic Kirchhoff type equation with a nonlinear source $$u^{{\prime}{\prime}}-M(x,t,{\parallel}{\bigtriangledown}u(t){\parallel}^2){\bigtriangleup}u+{\int}_0^th(t-{\tau})div[a(x){\bigtriangledown}u({\tau})]d{\tau}+{\mid}u{\mid}^{\gamma}u=0$$. Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.
MATHEMATICAL MODELLING FOR THE AXIALLY MOVING PLATE WITH INTERNAL TIME DELAY
Kim, Daewook The Youngnam Mathematical Society 2021 East Asian mathematical journal Vol.37 No.5
In [1, 2], we studied the string-like system with time-varying delay. Unlike the string system, the plate system must consider both longitudinal and transverse strains. First, we consider the physical phenomenon of an axially moving plate concerning kinetic energy, potential energy, and work dones. By the energy conservation law in physics, we have a nonlinear plate-like system with internal time delay.
Asymptotic behavior of a nonlinear Kirchhoff type equation with spring boundary conditions
Kim, Daewook,Jung, Il Hyo Elsevier 2011 COMPUTERS & MATHEMATICS WITH APPLICATIONS - Vol.62 No.8
<P><B>Abstract</B></P><P>In this paper, we consider the initial-boundary value problem for a nonlinear Kirchhoff type equation with the damping term and spring boundary conditions. We establish the global existence and uniqueness of solutions to this problem in time, and give an example and simulation to illustrate our results. For the proof, we use the Faedo–Galerkin approximate method. Finally, we study the asymptotic behavior of solutions and some of its simulation results. Results of this paper are able to apply industrial parts such as a typical model widely used to represent threads, wires, magnetic tapes, belts, band saws, and so on.</P>
Energy decay rate for a von Karman system with a boundary nonlinear delay term
Kim, Daewook,Park, Jong Yeoul,Kang, Yong Han Elsevier 2018 COMPUTERS & MATHEMATICS WITH APPLICATIONS - Vol.75 No.9
<P><B>Abstract</B></P> <P>In this paper, we show the energy decay rate for a von Karman system with a boundary nonlinear delay term. This work is devoted to investigate the influence of kernel function g and the effect of the boundary nonlinear term <SUB> μ 1 </SUB> <SUP> | <SUB> u t </SUB> ( t ) | m − 1 </SUP> <SUB> u t </SUB> ( t ) , a boundary nonlinear time delay term <SUB> μ 2 </SUB> <SUP> | <SUB> u t </SUB> ( t − τ ) | m − 1 </SUP> <SUB> u t </SUB> ( t − τ ) and prove energy decay rates of solutions when g do not necessarily decay exponentially and the boundary condition has a time delay.</P>
Considerable drag reduction and fuel saving of a tractor–trailer using additive aerodynamic devices
Kim, Jeong Jae,Kim, Jeongju,Hann, Taeseong,Kim, Daewook,Roh, Hong Seong,Lee, Sang Joon Elsevier 2019 Journal of wind engineering and industrial aerodyn Vol.191 No.-
<P><B>Abstract</B></P> <P>The drag reduction of commercial vehicles is the principal challenge to improving fuel saving and decreasing air pollution. Accordingly, several flow control devices, including gap fairing, cab roof fairing, boat tail, and side skirt were introduced to reduce the aerodynamic drag exerted on heavy vehicles. Although such devices have exhibited good drag reduction performance, their aerodynamic performance can be improved further. Moreover, a comprehensive and systematic research is required, including drag force measurement, flow field analysis and real-scale proving ground test, to evaluate the fuel consumption of heavy vehicles. In this study, the drag reduction effect of the aero full package (AFP) of a tractor–trailer, which integrated gap fairing, flap-type side skirt and lower inclined air deflector boat tail, was investigated through wind tunnel experiments and proving ground test. On the basis of the results of drag and PIV measurement, the integrated AFP was found to significantly modify the flow structure around the vehicle, thereby leading to a 26.5% reduction in drag coefficient compared with the reference tractor-trailer model (<I>C</I> <SUB> <I>D</I> </SUB> = 0.693). Furthermore, the proving ground test using real tractor–trailer verified that the integrated AFP provides 13.4% fuel saving. The present results will provide practical information for improving the aerodynamic performance and fuel efficiency of heavy vehicles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The aero full package for tractor-trailer consist of gap fairing, flap-type side skirt and LIAD boat tail was newly proposed. </LI> <LI> The aero full package reduces drag coefficient up to 26.5% compared with reference tractor-trailer. </LI> <LI> The flow structures around tractor-trailer model is revealed through PIV experiments. </LI> <LI> Real-scale proving ground test confirmed 13.4% fuel saving with the aero full package. </LI> </UL> </P>
Kim, Daewook The Youngnam Mathematical Society 2016 East Asian mathematical journal Vol.32 No.5
In this paper, we study the generalized Kirchhoff type equation in the presence of past and finite history $$\large u_{tt}-M(x,t,{\tau},\;{\parallel}{\nabla}u(t){\parallel}^2){\Delta}u+{\normalsize\displaystyle\smashmargin{2}{\int\nolimits_0}^t}\;h(t-{\tau})div[a(x){\nabla}u({\tau})]d{\tau}\\\hspace{25}-{\normalsize\displaystyle\smashmargin{2}{\int\nolimits_{-{\infty}}}^t}\;k(t-{\tau}){\Delta}u(x,t)d{\tau}+{\mid}u{\mid}^{\gamma}u+{\mu}_1u_t(x,t)+{\mu}_2u_t(x,t-s(t))=0.$$ Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the expoential decay rate of the Kirchhoff type energy.
Study on the Commercial Photography of the Post Photography Era
Daewook Kim,Joungwoo Joo 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.8
The beginnings of digital photography were humble, but now are overwhelming the silver halide photography in 2015. The term Post-Digital Photographic Era mentioned by Fred Ritchin refers to a characteristic image of digital photography with the appearance of digital photography and the beginning that the surrounding infrastructure changes. It means the era that the value framework that the existing photography had changes and a new paradigm begins to appear. Such a new paradigm is giving direct changes, i.e. technology generalization, to photographers and predicting drastic changes to society, culture, politics, and economy. This study looks at the present of photography through literature review of analog photos and digital photos from 1839 to 2015 and based on this literature, investigates the currently-emerging trends of photography and the post-photographic era. It also looks at various cases of technological advancement and presents the future directions for photography. Roland Barthes thought that photography is what was passed away, what was in the past, and what was dead. Through consideration on digital photography, virtual reality, and 3D image – products of various efforts for reviving such dead photos, it looks at the world of visual illusion, ultimate purpose of something virtual and studies the images of photography beyond being ubiquitous, the end of desire for a graphic virtual world.