• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.340-345
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• 1994

Dynamic hybrid position/force control of flexible manipulators is proposed. First, a 2 D.O.F. flexible manipulator is modeled using the spring-mass model. Second, the equation of motion considering the tip constraints is derived. Third, hybrid position/force control algorithm is derived. In this control algorithm, the differentiable order of the desired trajectory and the stability condition are different from the case of rigid manipulators. Lastly, to verify the effectiveness of the proposed control algorithm, simulation results are presented.

• 연구논문집
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• s.27
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• pp.35-45
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• 1997

The dynamic design process for the articulated bogie of light rail vehicle(LRV) was studied to design a primary and secondary suspension elements. Suspension stiffness and damping is selected on the basis of the ride quality and suspension stroke trade-off. LRV was modeled as a 2 d.o.f linear system for the design of vertical suspension characteristics and a 4 d.o.f linear system for the design of lateral suspension characteristics. FRA's class-4-track irregularity was used for the exciting disturbance on track. The optimum value of primary and secondary suspension characteristics was determined using this design process.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.99.1-99.1
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• 2008

• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.315-326
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• 1996

The electronic structures of 3d and 4d core-levels of rare-earth atoms in the insulating rare-earth (Sm, Eu, Gd, and Tb) compounds were studied with x-ray photoelectron spectroscopy(XPS). It is shown that the intrinsic satellite structure due to the hybridization disappears for chemically stable-earth trivalent heavy rare-earth insulating compounds as the hybridization between f electrons of rare-earth atoms and p electrons of anion atoms decreases due to the lanthanide contraction. Eu atoms at the surface of the stable insulating trivalent Eu compounds are found to be divalent. The satellite peak of Eu 3d core-level spectra at about 10eV higher binding energy side relative the main peak comes from the multiplet structures of $\underline{3d}4f^6$ configuration. The satellite structure appearing at about 15 eV higher binding energy side relative to the main peak in all insulating rare-earth compounds is due to an energy loss process of creating a plasmon.

• Wind and Structures
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• v.38 no.1
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• pp.59-74
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• 2024

Large Eddy Simulation (LES) is used to explore the influence of vibration frequency and amplitude on the aerodynamic performance of a rectangular cylinder with an aspect ratio of B/D=5 (B: breadth; D: depth of cylinder) at a Reynolds number of 22,000 near resonance frequency. In smooth flow conditions, the research employs a sequence of three-dimensional simulations under forced vibration with diverse frequency ratios f_e / f_o = 0.8-1.2 (f_e : oscillation frequency; f_o : Strouhal frequency when the rectangular cylinder is stationary ) and oscillation amplitudes A_h/D = 0.05 - 0.3. The individual influences of f_e / f_o and A_h/D on the characteristics of integrated and distributed aerodynamic forces are the focal points of discussion. For the integrated aerodynamic force, particular emphasis is placed on the analysis of the dependence of velocity-proportional component C₁ and displacement-proportional component C₂ of unsteady aerodynamic force on amplitude and frequency ratio. Near the resonance frequency, the dependencies of C₁ and C₂ on amplitude are stronger than that of frequency ratio. For the distributed aerodynamic force, the increase in frequency and amplitude promotes the position of the main vortex core and reattachment to the leading edge in the streamwise direction. In the spanwise direction, vibration enhances the spanwise correlation of aerodynamic force to weaken the three-dimensional effect of the flow field, and a lower frequency ratio and larger amplitude amplify this effect.

• Journal of Korean Society of Transportation
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• v.26 no.2
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• pp.147-156
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• 2008

It has been widely known that there are so many factors making travel demand errors in transportation forecasting steps. One of the reasons may stem from the level of aggregation of zone and network in analysis process. This paper investigates the effect of level of aggregation considering with number of zones in travel demand forecasting by expanding or reducing the zone and network gradually. Numerical results show that the aggregation could not make a significant impact on the travel demand, while disaggregation does. These results imply that a careful manipulation is required to add or to reduce zones and links in transportation planning process.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.157-166
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• 1995

The fate and use efficiency of applied nitrogen were evaluated in a pot experiment with different fertilizers and water management practices during 30days after fertilizer application. N-P-K compound fertilizers, 13-10-1l(F-l) for upland Crop use and 15-10-10(F-3) for rice Crop use, and mixed fertilizer, 21-17-17(F-2) for basal dressing in rice were used. Fertilizers corresponding to 1.8g N were mixed thoroughly with the whole volume of sandy loam soil in a pot. The pots were flooded upto 3cm above soil surface for O(0dF), 10(10dF), 20(20dF), and 30(30dF) days after fertilizer application and all the treatments were flooded continuously from 30 days after fertilizer application. During the flooding period water percolation rate was adjusted to 2.5mm/day. Rice seedlings were transplanted 40 days after fertilizer application. The pH of infiltrated water increased with increasing duration of flooding. The pH of F-2 was higher than those of F-1 and F-3 between which there were no differences. The applied nitrogen remained 23% in F-1, 29% in F-2, and 29.1 % in F-3, and 45.0% in 0dF, 26.6% in 10dF, 24.8% in 20dF, and 20.3% in 30dF as inorganic nitrogen at 63 days after fertilizer application. Nitrogen losses by leaching amounted to 51.3%, 32.1% and 48.1% of applied nitrogen in F-1, F-2 and F-3, respectively. Nitrogen leaching losses increased with increasing duration of flood- ing, amounting to 25.7%, 29.8%, 32.7%, and 35.8% in 0dF, 10dF, 20dF and 30dF, respectively. Gaseous loss of applied nitrogen was greatest in F-2, followed by F-1 and F-3. Total loss of nitrogen due to gaseous volatilization and leaching was greatest in F -1, followed by F -2 and F-3, and were greater in the treatments with longer flooding after fertilizer application. Nitrogen recovery by rice shoot until 72 days after transplanting were 23.2%, 24.7% and 27.4% of applied nitrogen in F-1, F-2 and F-3, respectively and 34.1%, 25.5%, 21.1%, and 21.2% in 0dF, 10dF, 20dF and 30dF, respectively.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.383-386
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• 1998

The microwave dielectric properties and sintering properties of the xCaTi $O_{3}$-yMgTi $O_{3}$-z(L $i_{1}$2/N $d_{1}$2/)Ti $O_{3}$ systems were investigated for the development of microwave dielectric materials. Dielectric constants decreased with increasing the amounts of MgTi $O_{3}$ and increased with reducing the amounts of MgTi $O_{3}$ and increased with reducing (L $i_{1}$2/N $d_{1}$2/)Ti $O_{3}$ contents. The microscopic structures were mixed phase with a little second phase. We found some compositions with .tau.$_{f}$ changed from positive to negative value with increasing MgTi $O_{3}$ or (L $i_{1}$2/N $d_{1}$2/)Ti $O_{3}$ contents. The microscopic strucstures were mixed phase with a little second phase. We found some compositions with .tau.$_{f}$ =0ppm/.deg.C. these compmsitions exhibited the stable dielectric properties on the various sintering temperatures.res.

• East Asian mathematical journal
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• v.17 no.2
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• pp.303-308
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• 2001

Let K($z,\gamma$) denote the euclidean curvature of the curve $\gamma$ at the point z. Flinn and Osgood proved that if f is a univalent mapping of the open unit disk D={z:|z|<1} into itself with f(0)=0 and |f'(0)|<1, then $K(0,\gamma){\leq}K(0,f\;o\;\gamma)$ for any $C^2$ curve $\gamma$ on D through the origin with $K(0,\gamma){\geq}4$. In this paper we establish a generalization of the Flinn-Osgood Monotonicity Theorem.

• Communications of the Korean Mathematical Society
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• v.26 no.3
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• pp.455-462
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• 2011

An analytic self-map ${\phi}$ of the open unit disk $\mathbb{D}$ in the complex plane and an analytic map ${\psi}$ on $\mathbb{D}$ induce the so-called weighted composition operator $C_{{\phi},{\psi}}$: $H(\mathbb{D})\;{\rightarrow}\;H(\mathbb{D})$, $f{\mapsto} \;{\psi}\;(f\;o\;{\phi})$, where H($\mathbb{D}$) denotes the set of all analytic functions on $\mathbb{D}$. We study when such an operator acting between different weighted Bergman spaces is bounded, compact and Schatten class.