• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.227-233
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• 1998

인공관절 라이너에 널리 사용되는 대표적 생체재료인 초고분자량 폴리에틸렌 (Ultra-High Molecular Weight Polyethylene)은 체내에 삽입되기 전에 멸균처리를 거쳐야 하며, 가장 보편적인 멸균 방법은 감마선을 이용한 멸균처리이다. 그러나, 감마선은 폴리에틸렌의 화학분자 결합구조에 변화를 일으키며, 따라서 물리적, 기계적 물성치에 변화를 야기 사려된다. 이는 인공관절 수명을 좌우하는 변형과 마모현상에도 결정적 영향을 줄 것으로 사려된다. 본 연구에서는 감마선 멸균처리가 UHMWPE의 크리프 변형 및 마모에 미치는 영향이 관찰되었고, 그 결과들은 감마선 멸균처리로 야기된 폴리에틸렌의 화학분자 결합구조의 변화(Crystallinity, Oxidation, Crosslinking)와 함께 분석되었다. 압출 제작된 초고분자량 폴리에틸렌 봉(extruded UHMWPE rod)으로부터 원통형의 시편을 제작하여 감마선 멸균처리를 행하고, 압축 크리프 실험과 마모 실험을 실시하여 멸균처리 하지 않은 시편의 결과와 비교하였다. 크리프 변형의 경우, 감마선 멸균처리 된 시편과 멸균처리 하지 않는 시편 사이에는 크리프 복원정도를 제외하고 거의 차이가 없었으나, 반면에 마모의 경우, 감마선 멸균처리 된 시편이 멸균처리 하지 않은 시편보다 훨씬 적은 마모량을 보였다 (p<0.05). 이것은 crosslinking 증가에 따른 마모 저항력 향상으로 볼 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.137-137
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• 2012

인공관절은 노인성 질환이나 자가 면역질환, 신체적인 외상 등으로 인하여 발생하는 관절의 손상 부위를 대체하기 위하여 고안된 관절의 인공 대용물이다. 인공 관절 중 인공 고관절의 경우 라이너(Liner)와 헤드(Head) 부분이 직접적인 마모 운동을 수행하게 되므로, 이 부분의 소재 특성에 따라 인공관절의 수명이 결정 되게 된다. 현재 헤드 소재로서는 Co-Cr-Mo 합금이, 라이너 소재로서는 고분자 소재인 UHMWPE (Ultra High Molecular Weight Polyethylene)가 주로 사용되고 있다. 이러한 MOP (Metal-On-Polymer) 구조의 인공관절의 경우, 충격흡수의 장점이 있는 반면, 관절 운동시 발생하는 UHMWPE 의wear debris에 의해 골용해가 발생하게 되어 인공관절의 수명이 저하되는 문제점이 있으며, 금속 헤드의 마모로 인한 금속이온의 용출은 세포 독성의 문제를 야기하여 인공관절의 수명을 저하시키는 또 다른 원인이 되고 있다. 따라서 본 연구에서는 PIII&D (Plasma Immersion Ion Implantation & Deposition) 공정을 이용하여 금속 (Co-Cr-Mo 합금)소재 위에 세라믹 (niobium nitride) 박막을 증착하여 상대재인 UHMWPE의 마모를 줄이고자 하는 연구를 진행하였다. 금속 소재 위에 증착된 세라믹 박막은 상대재인 UHMWPE의 마모량을 줄여줄 뿐만 아니라 금속이온의 용출을 막아준다는 장점이 있으나, 장시간의 마모 운동에 의하여 발생하는 박막의 박리 현상은 인공관절의 수명을 급격히 저하시키는 또 다른 원인이 된다. 이러한 단점을 해결하기 위하여, 박막의 증착 초기에 이온주입과 증착을 동시에 수행하는 dynamic ion mixing공정을 수행하였다. Dynamic ion mixing 공정을 수행함에 따라 박막과 금속 사이의 접착력이 증가하게 되어, UHMWPE의 마모량이 2배 가까이 감소하는 것을 확인할 수 있었으며, 장시간의 마모시험에서도 우수한 결과를 얻을 수 있었다. 또한 UHMWPE의 마모량을 감소시키기 위하여 박막을 증착하기 전에 금속 소재에 질소 이온주입을 수행하는 pre-ion implantation 공정을 도입하였다. 질소 이온주입 결과 Co-Cr-Mo 합금 표면에 부분적으로 CrN, Cr2N의 세라믹 상이 형성 되는 것을 확인할 수 있었으며, 그에 따라 UHMWPE의 마모량이 2배 이상 감소 되는 것을 확인 할 수 있었다.

• Macromolecular Research
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• v.12 no.1
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• pp.112-118
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• 2004

With the goal of enhancing the creep resistance of ultra-high molecular weight polyethylene (UHMWPE), we performed gamma irradiation and post-irradiation annealing at a low temperature, and investigated the crystalline structures and mechanical properties of the samples. Electron spin resonance spectra reveal that most of the residual radicals are stabilized by annealing at 100$^{\circ}C$ for 72 h under vacuum. Both the melting temperature and crystallinity increase after increasing the dose and by post-irradiation annealing. When irradiated with the same dose, the quenched sample having a higher amorphous fraction exhibits a lower swell ratio than does the slow-cooled sample. The measured tensile properties correlate well to the crystalline structure of the irradiated and annealed samples. For enhancing creep resistance, high crystallinity appears to be more critical than a high degree of crosslinking.

• Journal of Biomedical Engineering Research
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• v.18 no.2
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• pp.107-112
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• 1997

The effect of gamma-irradiation sterilization on molecular structural changes in orthopaedic surgical-grade polyethylene was studied. The relative crystallinity ud. percent crosslinking of the substance increased as a result of the gamma irradiation and varied anisotropically as a function of depth. Samples from the articulating surfaces showed 5% Venter relative crystallinity than those from the mid-sections, whereas samples from the mid-sections exhibited 15% greater crosslinking than those from the surfaces. These anisotropic variations are discussed in assDciation with oxidation.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.53-61
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• 2015

High-energy ball milling was tested as a method for producing Ultra High Molecular Weight Polyethylene (UHMWPE)- based nanodielectrics containing 1 wt% and 5 wt% OctaIsoButylPOSS (OibPOSS). Qualitative and quantitative evaluations were used to explore the compatibility between OibPOSS and PE. Several ball milling variables were optimized in a bid to achieve UHMWPE/OibPOSS nanodielectrics. The morphology, as well as the thermal and the dielectric properties of the samples, were characterized by scanning electron microscopy, thermogravimetric analysis, broadband dielectric spectroscopy, and progressive-stress breakdown tests. The results showed that (i) ball milling was an effective method for producing UHMWPE/OibPOSS dielectric composites, but appeared ineffective in dispersing OibPOSS at the nanoscale, and (ii) the resulting UHMWPE/OibPOSS dielectric composites presented thermal and dielectric properties similar to those of neat UHMWPE.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.257-258
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• 2018

PTFE(polytetrafluoroetylene) is widely used as representative sliding friction materials, but there could be difficulties in applying it to various industry fields by the shortage of carrying capacity under high facial pressure and by the change of friction coefficient according to the environmental conditions. Accordingly, this study was to do comparative analysis on the friction coefficient by environmental temperature at the same facial pressure of UHMWPE which was mainly used as sliding friction materials under high facial pressure. In addition, this study was to proceed with the double shear structure by using two test specimen in order to minimize the frictional forces.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.72-77
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• 2003

Nano-diamonds were added to Ultra-high molecular weight polyethylene (UHMWPE) to improve the tribological properties of UHMWPE. Nano-diamonds which have a diameter of about 5-10nm were produced by detonation. UHMWPE/nano-diamonds composites were fabricated by hot pressing method. It is shown that friction coefficient was increased and wear resistance was improved as nano-diamonds were added to UHMWPE because of excellent mechanical properties of nano-diamonds located on UHMWPE surface.

• Journal of Biomedical Engineering Research
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• v.22 no.6
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• pp.519-526
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• 2001

At present. about 0.3 million and more THRs (Total Hip Replacement) in a rear are being done worldwide. The increase in mechanical failure with the increase in THR, required more revisions. Revisions compensate mainly the wear of the artificial joint frictional surface and the loosening of the cup and stem. According to recent researches, loosening is mainly due to wear debris UHMWPE (Ultra High Molecular Weight Polyethylene) from frictional surfaces . To overcome the wear problems associated with artificial joint materials , new surface structures with regular Patterns were designed and fabricated The lubrication Properties were examined to evaluate the wear of the frictional surfaces. The surface structure manifested a Pattern of "dents" with a 0.2-1.0 mm of diameter and 0.6-2.0 mm of Pitch. From the friction test of the SUS316L vs UHMWPE using the frictional tester, we found that the lubrication Performance was improved due to of drastically reduced amount of abrasion. There were optimum sizes for the diameter and the pitch of the Pattern. The results demonstrated that the lubrication properties could be improved by Patterning of the frictional surfaces. The surface Patterning was effective in preventing wear of the frictional surfaces, and the life of an artificial joint could be extended with such Patterning.

• Textile Coloration and Finishing
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• v.31 no.2
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• pp.98-106
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• 2019

The dyeability and fastness properties of super-hydrophobic navy dyes having different length of alkyl groups were investigated on ultra high molecular weight polyethylene fabrics. Those dyes exhibited strong color strength in the wavelength of mainly 550~650nm, which meant that they were navy color. From the results accomplished under various dyeing conditions, it can be concluded that those dyes have higher affinity on the fibers at $130^{\circ}C$ than at the lower dyeing temperature. Considering processing time and thermal damage of the fibers, one hour is good enough to obtain full strength of color. Maximum color strength was obtained at 2~3%owf of pure dyes. Except for the rub fastness under dry condition, all fastness such as to washing and light showed as good as of 4~5 ratings.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.90-91
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• 1998

The influence of gamma-irradiation sterilization on the creep and wear performance of ultra-high molecular weight polyethylene (UHMWPE) was investigated by conducting the dynamic compressive creep tests and pin-on-disc sliding wear tests. The changes of microstructure property, relative crystallinity, oxidation index, percent crosslinking, were also measured and the relationship between these and creep and wear results was discussed.