• 폴리머
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• 제36권2호
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• pp.163-168
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• 2012

최근에 내시경 관련기술의 진보에 따라서 시술 편리성, 회복시간 단축, 환자 고통 경감 등의 장점으로 인해 스텐트 삽입술이 빠르게 진보하였다. 본 연구에서 양성담관 협착 치료를 목적으로 파클리탁셀을 이용한 약물방출 스텐트를 전기분사 방법에 의해 제조하였으며, 이 때 사용된 고분자는 polyether-based polyurethane(상표명 : PELLETHANE 2363-80AE$^{(R)}$)과 첨가제로서 Pluronic F127, 약물로서 파클리탁셀을 사용하여 금속스텐트 표면에 코팅하였다. 그 결과로서, 약물이 코팅된 고분자 필름의 물리적 특성은 SEM, FTIR, 접촉각 측정기, XRD에 의해 확인하였으며, 약물방출속도는 약물함량이 높을수록 감소하였음을 알 수 있었다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.235-236
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• 1998

The purpose of this paper is to develop diaphragm type pneumatic Left Ventricular Assist Device(LVAD) for clinical application and to evaluate its performance through the mock circulation and animal experiment. The blood housing and diaphragm are made by polyurethane. The relations of cardiac output us. beat rate and cardiac output vs. systolic-to-diastolic rate was estimated through the mock test and hemodynamic waves are recorded for the evaluation of VAD. We performed animal experiment and 4 animals survived more than 24hrs. As a result, the hemodynamic data and waves showed this system can be applicable to the animal experiment.

• 한국재료학회지
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• 제19권12호
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• pp.680-685
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• 2009

Using a polyurethane foam replica method, porous hydroxyapatite scaffolds (PHS) were fabricated using conventional and microwave sintering techniques. The microstructure and material properties of the PHS, such as pore size, grain size, relative density and compressive strength, were investigated at different sintering temperatures and holding times to determine the optimal sintering conditions. There were interconnected pores whose sizes ranged between about 300 ${\mu}m$ and 700 ${\mu}m$. At a conventional sintering temperature of 1100$^{\circ}C$, the scaffold had a porous microstructure, which became denser and saw the occurrence of grain growth when the temperature was increased up to 1300$^{\circ}C$. In the case of microwave sintering, even at low sintering temperature and short holding time the microstructure was much denser and had smaller grains. As the holding time of the microwave sintering was increased, higher densification was observed and also the relative density and compressive strength increased. The compressive strength values of PHS were 2.3MPa and 1.8MPa when conventional and microwave sintering was applied at 1300$^{\circ}C$, respectively.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.247-248
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• 1998

The effect of unattached valve leaflet on flow field downstream of a floating and flapping polyurethane heart valve prosthesis was investigated. With a triggering system and a time-delay circuit the instantaneous velocity field downstream of the valve was measured by particle image velocimetry (PIV) in conjunction with the opening posture of a flexible valve leaflet during a cardiac cycle. Reynolds shear stress distribution was calculated from the velocity fields and wall shear stress was directly measured by hot-film anemometry (HFA). The floating motion of the valve leaflet resulted in the reduction of pressure drop and recirculating flow region downstream of the valve.

• 대한의용생체공학회:의공학회지
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• 제15권1호
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• pp.19-26
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• 1994

Sulfonated poly (ethyleneoxide)-grafted polyurethane (PU-PEO-$SO_3$) prepared by bulk modification was coated on a blood sac for electrohydraulic left ventricular assist device (ELVAD) implanted in dogs and its in vivo blood compatibility on shear stress was studied as compared with untreated Po. The effect of the wall shear stress on the protein adsorption unlike platelet adhesion is dependent on the surface characteristics of the material, although less proteins seem to be adsorbed in the region of the high shear stress. The thickness of total proteins adsorbed on PU-PEO-SOJ (400 ${\AA}$) by trans¬mission electron microscopy(TEM) was considerably lower than that of untreated PU(l,000~1,600 ${\AA}$), but PU-PEO-$SO_3$ showed high albumin adsorption, low fibrinogen and IgG adsorption, and low platelet adhesion as compared with untreated PU, suggesting that PU-PEO-$SO_3$ is more in vivo blood compatible. Therefore, it appears that such a blood compatible PU-PEO-$SO_3$ is useful for blood contacting biomaterials including artificial organs.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.447-450
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• 1997

A new technique for the preparation of porous vascular prostheses was investigated. Polyurethane solution (10 to 14wt%) was injected into a mold. After freezing at low temperature $(0^{\circ}C\sim-40^{\circ}C)$, solvent was dissolved out with water at $0^{\circ}C$ to form porous tubes. The average pore size $(<10{\mu}m)$and pore occupation (10% to 51%) were easily changed by changing polyurethane concentration, freezing temperature, and freezing methods. This technique can give a proper pore size $(30\sim60{\mu}m)$ for tissue ingrowth, and suitable compliances for matching with arteries and veins. This method might give a desired compliant graft for artificial implantation with the presently valid medical polymers.

• 대한의용생체공학회:의공학회지
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• 제20권2호
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• pp.221-230
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• 1999

다공성 인공 혈관을 제조하기 위한 새로운 기술에 대하여 연구하였다. 제조방법을 달리하여 만든 다공성의 시편을 준비하여 여러 가지 물성을 비교하였다. 용매/비용매 교환법에 의한 다공성 부여 방법과 고분자 용액의 냉각에 따른 상전이 현상을 이용하여 고분자 용액의 농도와 냉각속도를 달리하여 인공 혈관 시편을 제작하였다. 고분자 용액의 농도가 감소할수록 그리고 냉각속도가 작을수록 인공 혈관 재료로서 유리한 물성을 지닐 수 있음을 알 수 있었다. 위의 방법으로 다공성을 조절함으로써 재료의 기계적 물겅 또한 조절할 수 있음을 알 수 있었다. 냉각 속도를 조절하여 다공성을 부여하는 방법을 이용하여, 고안된 몰드를 사용하여 기존에는 만들기 어려웠던 균일한 두게의 U자형 소구경 인공 혈관을 만들 수 있었다. 비교적 간단한 도구로 균일한 물성을 지니며 원하는 물성의 인공 혈관을 제조할 수 있었다. 온도를 조절하여 고분자 박막에 다공성을 부여하는 기술은 다양한 기능의 의료용 고분자에 접목하여 필요로 하는 기능성을 부여할 수 있는 중요한 기술로 이용할 수 있을 것이다.

• 한국건설순환자원학회논문집
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• 제3권4호
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• pp.348-354
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• 2015

현재 국내에서 가장 많이 시공되고 있는 우레탄 방수재는 시공이 간편하고 이음매 없이 도막을 만들 수 있다는 장점을 가지고 있지만, 저온 및 낮은 습도에서 경화지연 및 도막 두께의 제한과 같은 결점이 있어서 현장 시공 시에 물을 강제적으로 혼합하여 경화시키는 방법인 수경화성 폴리우레탄 방수재가 해결방안으로 제시되고 있다. 하지만, 수경화성 폴리우레탄 방수재는 경화제로 사용하는 물 혼합비에 따라 방수성능 및 현장 시공성에 어떠한 영향을 주게 되는지에 대한 객관적이고 정량적인 평가가 없는 실정이다. 따라서 시공현장에서는 객관적인 기준 없이 작업자의 판단에 따라 물을 혼합하여 시공하고 있어서 일정한 성능과 품질을 얻을 수 없는 문제점이 있다. 따라서, 본 연구에서는 수경화성 폴리우레탄 방수재가 폭 넓게 적용되는 계기를 만들기 위하여, 물 혼합비에 따른 성능의 변화를 정량적인 근거를 바탕으로 평가, 분석하여 적정한 물 혼합비 제안을 위한 기초적 자료를 마련하기 위해 진행하였다. 연구의 방법은 수경화성 폴리우레탄 방수재의 물 혼합비(0%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%)에 따른 객관적 성능 평가를 통해 결과 값을 도출하고 비교 분석하여 혼합비별 물성변화 특성을 파악한 후 이를 데이터 베이스화 하여 가장 적정한 물 혼합비 제안을 위한 기초적인 자료로 활용 가능할 수 있도록 결과를 제시하였다.

• 대한의용생체공학회:의공학회지
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• 제14권4호
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• pp.307-314
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• 1993

Plasma protein adsorption is the first event in the blood-material interaction and influenc- es subsequent platelet adhesion towards thlㅈombus formation. Thiㅈomboembolic events are strongly influenced by surface characteristics of materials and fluid dynamics inside the blood pump. In vitro flow visualizaion and an amimal experiment with the moving actuator type TAH were Performed in order to investigate fluid dynamic effects on the protein adsorption. The diffel'encl level, j of shear rate inside the ventricle Lvere determined by consid- ering the direction of the major opening of four healt valves in the implanted TAH and the visualized flow patterns as well. Each ventricle of the explanted TAH was sectionalized into 12 segments according to the shear rate level. The adsorbed protein on each segment was quantified using the ELISA method after soaking in 2% (wye)SDS/PBS for two days. Adsorbed protein layer thicknesses Itvere measured by the Immunogotd method under TEM. The SEM observation show that right ventricle (RV) , immobilized with albumin, displayed different degrees of platelet adhesion on each segment, whereas the left ventricle (LV), grafted by PEO-sulronate, indicated nearly , iame platelet adhesion behavior, regardless of shear rates. The surface concentrations of adsorbed proteins in the low shear rate region are hlghel'than those in the high region, which was confirmed statistically. A modified adsorption model of plasma protein onto polyurethane surface was suggested by considering the effect of the fluid dynamic characteristics.

• 한국재료학회지
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• 제20권8호
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• pp.418-422
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• 2010

As a starting material, BCP (biphasic calcium phosphate) nano powder was synthesized by a hydrothermal microwave-assisted process. A highly porous BCP scaffold was fabricated by the sponge replica method using 60 ppi (pore per inch) of polyurethane sponge. The BCP scaffold had interconnected pores ranging from $100\;{\mu}m$ to $1000\;{\mu}m$, which were similar to natural cancellous bone. To realize the antibacterial property, a microwave-assisted nano Ag spot coating process was used. The morphology and distribution of nano Ag particles were different depending on the coating conditions, such as concentration of the $AgNO_3$ solution, microwave irradiation times, etc. With an increased microwave irradiation time, the amount of coated nano Ag particles increased. The surface of the BCP scaffold was totally covered with nano Ag particles homogeneously at 20 seconds of microwave irradiation time when 0.6 g of $AgNO_3$ was used. With an increased amount of $AgNO_3$ and irradiation time, the size of the coated particles increased. Antibacterial activities of the solution extracted from the Ag-coated BCP scaffold were examined against gram-negative (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus). When 0.6 g of $AgNO_3$ was used for coating the Ag-coated scaffold, it showed higher antibacterial activities than that of the Ag-coated scaffold using 0.8 g of $AgNO_3$.