• Proceedings of the KSME Conference
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• 대한기계학회 2004년도 춘계학술대회
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• pp.438-443
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• 2004

Court sport shoes is consisted of several functional parts such as soles, upper and midfoot reinforcements. Currently, intensive research for court sport shoes considering functional parts is in progress world widely, but the shoes design relies only on the view point of kinesilogy and biomechanics until now. Thus, more scientific and reliable evaluation of shoes characteristics is definitely required. In this paper, we evaluate the landing impact of court sport shoes by using finite element method. We construct a shoes-leg coupled FEM model which can simulate effectively impact in running mode. From the numerical analysis results, the designer can establish the advanced design concepts and build up the detailed design standard for the specific court sport shoes under consideration.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제22권5호
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• pp.967-973
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• 1997

In this paper, the designed and fabrication of a K-band push-push oscillator using miniaturized hairpin resonator have been presented. One experimenal oscillator has been designed and fabricated for K-band point-to-point operation. the miniaturized harpin resonator has been analyzed theoretically and simulated by MPIE(Mixed Potential Integral Equation) method. With this results, the analysis of hairpin resonator which coupled microstrip line has been carried out with transmission-mode using this results. an optimized output matching network for the suppression of the fundamental and the 3rd order harmonic was acquired by using a nonlinear analysis method. The fabricated oscillator shows the output power of -2.28dBm, the fundamental frequency suppression of -19dBc, the 3rd order harmonic suppressionof -24dBc and 0.33 percent effiiency at 22.8GHz. The experimental outputs are in good agreement with the theoretical and simulated results.

• Structural Engineering and Mechanics
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• 제30권4호
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• pp.427-444
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• 2008

A mathematical model for the nonlinear dynamics of a rotating beam with flexible root attached to a rotating hub with elastic foundation is developed. The model is developed based on the large planar and flexural deformation theory and the potential energy method to account for axial shortening due to bending deformation. In addition the exact nonlinear curvature is used in the system potential energy. The Lagrangian dynamics and the assumed mode method is used to derive the nonlinear coupled equations of motion hub rotation, beam tip deflection and hub horizontal and vertical displacements. The derived nonlinear model is simulated numerically and the results are presented and discussed for the effect of root flexibility, hub stiffness, torque type, torque period and excitation frequency and amplitude on the dynamic behavior of the rotating beam-hub and on its stability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.745-749
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• 2001

The rigid body properties of a structure may be estimated easily if the mass-line of the structure could be taken exactly. However, the exact mass-line cannot be obtained experimentally. In the past years, the modal analysis for which the structure is mounted on the flexible supporter is frequently used to acquire the mass-line. Unfortunately, it is difficult not only to mount the structure but also to decouple the coupled 6 dof mode. If the structure is pended by very long and flexible rope to act free, the rigid-body modes influenced by the rope will be eliminated and the improved mass-line will be obtained. In this paper, the method using the mass-line of F.R.F. for rigid body in free-condition is suggested. The robustness of the suggested method was tested and verified numerically. The experimental results also showed a good agreement with the true value.

• Natural Product Sciences
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• 제24권4호
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• pp.288-292
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• 2018

High-performance countercurrent chromatography (HPCCC) coupled with reversed-phase highperformance liquid chromatography (RP-HPLC) method was developed to isolate dihydrophaseic acid 3'-O-${\beta}$-D-glucopyranoside (DHPAG) from the extract of Nelumbo nucifera seeds. Enriched DHPAG sample (2.3 g) was separated by HPCCC using ethyl acetate/n-butanol/water system (6:4:10, v/v/v, normal-phase mode, flow rate: 4.0 mL/min) to give 23.1 mg of DHPAG with purity of 88.7%. Further preparative RP-HPLC experiment gave pure DHPAG (16.3 mg, purity > 98%). The current study demonstrates that utilization of CCC method maximizes the isolation efficiency compared with that of solid-based conventional column chromatography.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1689-1692
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• 2013

Food is a common source of chromium (Cr) exposure. However, it is difficult to analyze Cr in complex food matrices by using inductively coupled plasma mass spectrometry (ICP-MS) because the major isotope, $^{52}Cr$, is masked by interference generated by the sample matrix and the plasma gas. Among the systems available to minimize interference, the recently developed collision-reaction interface (CRI) has a different structure relative to that of other systems (e.g., collision cell technology, octopole reaction system, and dynamic reaction cell) that were designed as a chamber between the skimmer cone and quadrupole. The CRI system introduces collision or reaction gas directly into the plasma region through a modified hole of skimmer cone. We evaluated the use of an CRI ICP-MS system to minimize polyatomic interference of $^{52}Cr$ and $^{53}Cr$ in various foodstuffs. The $^{52}Cr$ concentrations measured in the standard mode were 2-3 times higher than the certified values. This analytical method based on an ICP-MS system equipped with a CRI of helium gas was effective for Cr analysis in complex food matrices.

• Structural Engineering and Mechanics
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• 제61권2호
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• pp.231-244
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• 2017

The aim of this study is to develop a semi-analytical method to investigate fluid-structure coupling of concentric double shells with different lengths and elastic behaviours. Co-axial shells constitute a cylindrical circular container and a baffle submerged inside the stored fluid. The container shell is made of functionally graded materials with mechanical properties changing through its thickness continuously. The baffle made of steel is fixed along its top edge and submerged inside fluid such that its lower edge freely moves. The developed approach is verified using a commercial finite element computer code. Although the model is presented for a specific case in the present work, it can be generalized to investigate coupling of shell-plate structures via fluid. It is shown that the coupling between concentric shells occurs only when they vibrate in a same circumferential mode number, n. It is also revealed that the normalized vibration amplitude of the inner shell is about the same as that of the outer shell, for narrower radial gaps. Moreover, the natural frequencies of the fluid-coupled system gradually decrease and converge to the certain values as the gradient index increases.

• Smart Structures and Systems
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• 제19권5호
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• pp.523-538
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• 2017

A series of field vibration tests are conducted on the Runyang Suspension Bridge during both the construction and operational stages. The purpose of this study is devoted to the analysis of the dynamic characteristics of the suspension tower. After the tower was erected, an array of accelerometers was deployed to study the evolution of its modal parameters during the construction process. Dynamic tests were first performed under the freestanding tower condition and then under the tower-cable condition after the superstructure was installed. Based on the identified modal parameters, the effect of the pile-soil-structure interaction on dynamic characteristics of the suspension tower is investigated. Moreover, the stiffness of the pile foundation is successfully identified using a probabilistic finite model updating method. Furthermore, challenges of identifying the dynamic properties of the tower from the coupled responses of the tower-cable system are discussed in detail. It's found that compared with the identified results from the freestanding tower, the longitudinal and torsional natural frequencies of the tower in the tower-cable system have changed significantly, while the lateral mode frequencies change slightly. The identified modal results from measurements by the structural health monitoring system further confirmed that the vibrations of the bridge subsystems (i.e., the tower, the suspended deck and the main cable) are strongly coupled with one another.

• Journal of the Institute of Convergence Signal Processing
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• 제5권4호
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• pp.317-324
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• 2004

Electromagnetically coupled coaxial dipole (ECCD) array antenna with and without short-ended termination is investigated theoretically. The integral equations are derived for the structure by use of the Fourier transform and mode expansion of radial waveguide. The integrals appearing in the integral equations are evaluated along the branch cut instead of real axis for a faster convergent integral. The effects of slots and dipoles, short-ended termination length, and dielectric coating on the radiation characteristics are presented. Radiation pattern of the structure is also investigated. The results of the present method are compared with those of the commercial EM simulator and good agreement is found.

• Journal of Ocean Engineering and Technology
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• 제15권1호
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• pp.19-25
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• 2001

Unlike structures in the air, the vibration analysis of a submerged or floating structure such as offshore structures or ships is possible only when the fluid-structure interaction is understood, as the whole or part of the structure is in contact with water. This paper introduces two methods to find natural frequency in consideration of fluid-structure interaction, direct coupled vibration analysis and fluid-structure modal coupled vibration analysis. The purpose of this study is to analyze the vibration characteristic of a submerged vehicle to obtain the anti-vibration design data, which could be used in the preliminary design stage. The underwater pressure hull of submerged vehicle is used as the model of this study. The F.E.M. model is meshed by shell and beam elements. Also, considering the inner hull weight, the mass element is distributed in the direction of hull length. Numerical calculations are accomplished by using the commercial B.E.M. code. The characteristics of natural frequency, mode shape and frequency-displacement response are analyzed.