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PVA 성분비에 의한 PVA-Hydrogel의 점탄성 성질에 대한 연구
한창완(C. Han),김한종(H. Kim),이영석(Y. Lee),박성훈(S. Park) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.5
Polyvinyl Alcohol-Hydrogel (PVA-H) is a biomaterial used for manufacturing contact lenses as well as for the medium of drug delivery. Previous studies have also showed that PVA-H exhibits superior biocompatibility with hydrophilic elastic nature. The aim of this study is to examine the possible usage of the PVA-H as cartilage replacement material by determining the static and dynamic mechanical properties of PVA-H with different ratios of polyvinyl alcohol (PVA) and phosphate buffered saline (PBS) compositions. Three different types of PVA-H specimens were made by changing the ratio of PVA (Sigma-Aldrich) and PBS (Sigma-Aldrich) compositions (PVA-H1: 10wt% PVA and 90 wt% PBS; PVA-H2: 20wt% PVA and 80 wt% PBS; PVA-H3: 25 wt% PVA, 45 wt% PBS and DMSO 30 wt%). Static and dynamic tensile tests under the loading frequencies of 0.001, 0.01, 0.1, and 1 Hz were carried out to measure the biomechanical properties of PVA-H1, -H2 within PBS solution and -H3 within PBS/ DMSO solution. The equilibrium Youngs moduli (EY) of PVA-H1, -H2 and -H3 evaluated from the static displacement control were 84.2±35.1 kPa (n=10), 254±32.2 kPa (n=10) and 588±38.9 kPa (n=5), respectively. The amplitudes of dynamic tensile moduli were varied from 86.3±33.4 kPa (n=10) at 0.001 Hz to 96.9±42.0 kPa (n=10) at 1 Hz for PVA-H1, 282.7±26.4 kPa (n=10) at 0.001 Hz to 309.1±32.2 kPa (n=10) at 1 Hz for PVA-H2 and from 643.8±49.8 kPa (n=10) at 0.001 Hz to 747.7±67.7 kPa (n=5) at 1 Hz for PVA-H3. According to the current results, the frequency dependence of the magnitude of the dynamic modulus confirms the viscoelastic nature of PVA-H material. However, it can be noted that the dynamic modulus increases by up to a factor of 1.15 for PVA-H1, 1.22 for PVA-H2 and 1.27 for PVA-H3, showing insignificant viscoelasticity compared with that for cartilage. The result that static and dynamic moduli of PVA-H3 are larger than those of PVA-H1 and PVA-H2 also suggests that the amount of PVA composition in PVA-H plays an important role in improving both static and dynamic mechanical strengths of PVA-H plays an important role in improving both static and dynamic mechanical strengths of PVA-H material. The phase angle decreased from 5.2±2.1 ˚ at 0.001 Hz to -0.3±1.7 ˚ at 1 Hz for PVA-H1, from 5.6±0.6 ˚ at 0.001 Hz to -0.3±0.7 ˚ at 1 Hz for PVA-H2 and from 8.2±1.1 ˚ at 0.001 Hz to 0.7±0.7 ˚ at 1 Hz for PVA-H3.
김현수(H.S.Kim),김한종(H.J.Kim),허재영(J.Y.Hur),최창식(C.S.Choi),이제필(J.P.Lee),장철호(C.H.Jang),정종태(J.T.Jeong) 전력전자학회 1997 전력전자학술대회 논문집 Vol.1997 No.-
In large power system, design margin makes relatively price higher. So, optimal design through exact analysis of thermal behavior is needed. In this paper, we propose the equivalent load test facility using two inverter & converter system and inductors. Applying actual electrical profiles for motor drive, thermal characteristics of power converter fed AC motor drive are obtained, and the results are compared with simulation results.