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Sensory-parietal cortical stimulation improves motor recovery in severe capsular infarct
Kim, Ra Gyung,Cho, Jongwook,Ree, Jinkyue,Kim, Hyung-Sun,Rosa-Neto, Pedro,Kim, Jin-Myung,Lee, Min-Cheol,Kim, Hyoung-Ihl SAGE Publications 2016 Journal of cerebral blood flow and metabolism Vol.36 No.12
<P> The prevalence of subcortical white matter strokes in elderly patients is on the rise, but these patients show mixed responses to conventional rehabilitative interventions. To examine whether cortical electrical stimulation can promote motor recovery after white matter stroke, we delivered stimulation to a small or wide region of sensory-parietal cortex for two weeks in a rodent model of circumscribed subcortical capsular infarct. The sham-operated group (SOG) showed persistent and severe motor impairments together with decreased activation in bilateral sensorimotor cortices and striatum. In contrast, sensory-parietal cortex stimulation significantly improved motor recovery: final recovery levels were 72.9% of prelesion levels in the wide stimulation group (WSG) and 37% of prelesion levels in the small stimulation group (SSG). The microPET imaging showed reversal of cortical diaschisis in both groups: in both hemispheres for the WSG, and in the hemisphere ipsilateral to stimulation in the SSG. In addition, we observed activation of the corpus callosum and subcortical corticostriatal structures after stimulation. The results from the c-Fos mapping study were grossly consistent with the microPET imaging. Sensory-parietal cortex stimulation may therefore be a useful strategy for overcoming the limits of rehabilitative training in patients with severe forms of subcortical capsular infarct. </P>
공기압 타이어와 비 공기압 타이어의 노면 충격 시 에너지 손실 연구
김진규(Jinkyu Kim),조홍준(Hongjun Jo),김희철(Heecheol Kim),김두만(Dooman Kim) 한국자동차공학회 2014 한국 자동차공학회논문집 Vol.22 No.1
For the prevention of environmental pollution, there have been many researches which are eco-friendly vehicles in the automobile industry. In this paper, we studied for the non-pneumatic tires(NPT)can increase fuel consumption compared to conventional pneumatic tires. On driving, energy loss of tires occur when tires impact an obstacle on the road. This energy loss directly is relate to the fuel efficiency. Therefore, the energy loss of non-pneumatic tires is compared before and after impact. In this study, the results of energy loss of non-pneumatic tires and pneumatic tires was compared, when tires are rolled over an obstacle. As a result, the energy loss of non-pneumatic tires was less than pneumatic tires. This researches were performed the ABAQUS using finite element method and obtained the difference of velocity and kinetic energy from the program.
Preliminary study on a composite steel slit damper
Jinkyu Kim,김민철,Dongkeon Kim 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9
A steel slit damper has been used to enhance the seismic performance of structures with several advantages. The damper can be easily manufactured at a low cost. Furthermore, it can dissipate a significant amount of seismic energy through the stable hysteretic behavior of steel. This study presents a preliminary investigation of the development of a composite steel slit damper that can respond effectively at multiple levels of seismic loading. The performance of the prototype composite steel slit damper is investigated in both experimental and analytical ways. In the experiments, the specimen shows the stable hysteretic response with sufficient ductility, where the multi-phased response is observed in the incremental-amplitude cyclic loading case. Furthermore, a nonlinear numerical analysis that combines both kinematic hardening and isotropic hardening models can reliably describe such characteristics.
Jinkyu Kim,Dongkeon Kim 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.9
A common approach for dynamic analysis in current practice is based on a discrete time-integration scheme. This approach can be largely attributed to the absence of a true variational framework for initial value problems. To resolve this problem, a new stationary variational principle was recently established for single-degree-of-freedom oscillating systems using mixed variables, fractional derivatives and convolutions of convolutions. In this mixed convolved action, all the governing differential equations and initial conditions are recovered from the stationarity of a single functional action. Thus, the entire description of linear elastic dynamical systems is encapsulated. For its practical application to structural dynamics, this variational formalism is systemically extended to linear elastic multidegree-of-freedom systems in this study, and a corresponding weak form is numerically implemented via a quadratic temporal finite element method. The developed numerical method is symplectic and unconditionally stable with respect to a time step for the underlying conservative system. For the forced-damped vibration, a three-story shear building is used as an example to investigate the performance of the developed numerical method, which provides accurate results with good convergence characteristics.