연골세포 부착력 평가

이권용(Kwon-Yong Lee),박상국(Sang-Guk Park),Deahwan Shin,박종철(Jong-Chul Park) 한국트라이볼로지학회 2005 한국윤활학회지(윤활학회지) Vol.21 No.5

In order to prepare for the suitable surfaces of implants or medical devices, quantitative evaluation of adhesion between cells and biomaterials is essential. To better understand adhesion formation between cells and biomaterials, we used the cytodetachment technique which measures the adhesive force of a single cell through changing the culture time and detachment speed. The results showed that the adhesive force could be affected by the culture time of cells on the surface of materials and the detachment speed. Moreover, there was a large discrepancy among the adhesion strength measured by similar techniques conducted on the different cells and substrates. It can be concluded that the variation of the force measurement technique can seriously alter the level of the force required to detach a cell on the surface of materials.

감마선 조사된 초고분자량 폴리에틸렌의 마모 저항성 향상

이권용(Kwon Yong Lee),이근호(Keun Ho Lee),김신윤(Shin Yoon Kim),서승록(Seung Lock Seo) 대한고관절학회 1999 Hip and Pelvis Vol.11 No.3

The effect of gamma-irradiation sterilization on the wear resistance of UHMWPE was character-ized and its results were analyzed with typical microstructural properties such as the level of oxida-tion and crosslinking. A Ram-extruded un-irradiated UHMWPE rod and a gamma-irradiated acetabu-lar cup were tested with a pin-on-disk wear testing machine, FTIR, and hot xylene extraction. The wear of gamma-irradiated specimens was significantly less (p<0.05) than that of non-irradiated speci-mens. Gamma-irradiation induced an increase in the level of crosslinking as well as oxidation. According to other reports, oxidative degradation accompanying the brittleness deteriorates the wear performance, while the higher crosslinking level, the higher wear resistance. Combining this concept with the results from the present study, it can be inferred that the advautage of higher crosslinking overcomes the adverse effect of oxidation on wear. After a certain period after gamma-irradiation, oxidative degradation will overwhelm the crosslinking effect on wear. Therefore, it is necessary to analyze the change of oxidation and crosslinking on the various aged UHMWPE and correlate those results with the wear data from them.

치과용 저작 매스티케이터의 개발

이권용(Kwon-Yong Lee),정일영(Il-Young Jung),박성호(Sung-Ho Park),전승범(Seung-Beom Jeon) 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.35 No.-

Dental chewing masticator, which is an essential device for evaluating the wear of dental resin and the interfacial failure between the filling resin and enamel of tooth used in conservative dentistry, was developed. This dental chewing masticator mimics the chewing motion and loading by adapting DC motor and rotary cam system. Chewing loading of 49N was imposed by computer-displacement control, loadcell, LM guide, and spring system. Extracted tooth was fixed into a holding jig, and this jig was mounted with rubber pad on the 15°inclined surface to consider the lateral movement of periodontal ligament. A water bath was installed for providing the environment of inside mouth and for circulating the 5℃-55℃ water to evaluate the effect of hydrothermal cycling on the damage of resin filled teeth during long-term chewing activity.

감마선 조사 방법에 따른 정형외과용 초고분자량 폴리에틸렌의 미세구조 변화

이권용(Kwon Yong Lee) 한국고분자학회 2010 폴리머 Vol.34 No.5

본 연구에서는 인공관절 베어링 부품으로 가장 널리 사용되는 초고분자량 폴리에틸렌(UHMWPE)을 대상으로 6가지 감마선 조사 방법에 따른 UHMWPE의 미세구조 변화를 비교 분석하였다. 감마선을 조사하지 않은 폴리에틸렌(UGI)과 비교하여, 기존의 멸균처리에 해당하는 공기 중 상온에서 감마선 조사한 폴리에틸렌(AR)의 결정화도와 가교정도는 유의한 차이를 보이며 증가하였다. 감마선 조사 환경 중. 상온에서의 산소(AR)와 진공상태(VR) 영향을 비교하면, AR과 VR의 결정화도는 유의한 차이가 없었으며, VR의 가교정도는 유의한 차이를 보이며 증가하였다. 감마선 조사 환경 중, 진공상태에서의 상온(VR)과 극저온(V77) 영향을 비교하면, 결정화도와 가교정도 모두 유의한 차이가 없었다. 그러나, VR과 V77에서의 가교정도는 AR에서의 가교정도보다 유의한 차이를 보이며 증가하였다. 3가지 감마선 조사 환경에 대하여 감마선 조사 이후 열처리(/S) 영향을 비교하면, 결정화도는 AR/S와 VR/S에서 유의한 차이가 없었으나, V77/S에서는 유의한 차이를 보이며 감소하였다. 또한, 가교정도는 AR/와 V77/S에서 유의한 차이를 보이며 증가하였으며, VR/S에서는 유의한 차이가 없었다. In this study, the microstructural changes in orthopaedic-grade ultra high molecular weight polyethylene (UHMWPE) were compartively investigated for six different gamma-irradiation methods. Compared with un-irradiation (UGI), conventional gamma-irradiation in air room temperature (AR) induced statistically significant increases of relative crystallinity and percent crosslinking in UHMWPE. Vacuum environment (VR) during gamma-irradiation significantly increased the percent crosslinking in UHMWPE. Vacuum extreme low temperature (V77) during gamma-irradiation induced no significant changes in both relative crystallinity and percent crosslinking of U1IMWPE but the percent crosslinking of UHMWPE in VR and V77 was significantly larger than that in AR. Post-irradiation stabilization process significantly increased the relative crystallinity of UHMWPE in V77, and it also significantly increased the percent crosslinking of UFIMWPE in AR and V77.

Cyto-indentation 방법을 이용한 연골세포의 탄성계수 측정

이권용(Kwon-Yong Lee),박상국(Sang-Guk Park),김병수(Byung-Soo Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Tissue engineering has been proposed to restore tissue composition, structure, and mechanical function. Previous studies showed that tissue engineered cartilage were grossly and histologically similar to normal natural cartilage, but the mechanical properties were significantly lower than those of natural cartilage. Before chondrocytes grow to form subcutaneous cartilage tissue, it was assumed that chondrocyte having the higher mechanical property might construct the better cartilage having improved mechanical performanc. A cytoindentation technique was used to obtain the biomechanical Young's Modulus of a chondrocyte cell attached to glass surface. Piezo-transducer system and dual photo-diode system were used to conduct mechanical indentation through displacement-controlled testing and the measurement of corresponding cell reaction force. The Young's Modulus of chondrocyte, that was determined by elastic contact theory, was 1.38 ㎪. The cytoindentation technique employed in this study is so precise that it can quantify the biomechanical Young's Modulus of single cell.

Cyto-detachment 방법을 이용한 연골세포의 부착력 측정

이권용(Kwon-Yong Lee),박상국(Sang-Guk Park),Daehwan Shin,박종철(Jong-Chul Park) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

In order to prepare for the suitable surfaces of implants or medical devices, quantitative evaluation of adhesion between cells and biomaterials is essential. To better understand adhesion formation between cells and biomaterials, we used the cytodetachment technique which measures the adhesive force of a single cell through changing the culture time and detachment speed. The results showed that the adhesive force could be affected by the culture time of cells on the surface of materials and the detachment speed. Moreover, there was a large discrepancy among the adhesion strength measured by similar techniques conducted on the different cells and substrates. It can be concluded that the variation of the force measurement technique can seriously alter the level of the force required to detach a cell on the surface of materials.

저작재현장치의 개발

박성호,정일영,이권용,Park, Sung-Ho,Jung, Il-Young,Lee, Kwon-Yong 대한치과보존학회 2003 Restorative Dentistry & Endodontics Vol.28 No.1

Chewing simulator, which can partly mimic the motion of chewing motion of human, has been successfully developed. The purpose of its development was to make a new machine which can anticipate the clinical results of restoration in the human teeth more accurately in vitro condition It is composed of 4 major parts, chewing part, motor part, water bath, controlling part. The controlling part control the chewing force, frequency, the temperature and running time of water. Additionally, the actual chewing force and remaining time is shown in the monitor of controlling part. At present, the chewing cycle is composed depending on the pre-published data of foreign people. Long term clinical data should be additionally collected for the simulator to mimic the clinical results more accurately.

Halogen Light Curing Unit과 Light Emitting Diodes Curing Unit을 이용하여 중합되어진 복합레진의 마멸 특성 비교

김환(Hwan Kim),이권용(Kwon-Yong Lee),박성호(Sung-Ho Park),정일영(Il-Young Jung),전승범(Seung-Beom Jeon) 한국트라이볼로지학회 2005 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.21 No.6

In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji Ⅱ LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15 N contact force in a reciprocal sliding motion of sliding distance of 10 mm/cycle at 1 Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP > Surefil > Compoglass > Z100 > Fuji Ⅱ LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji Ⅱ LC specimen was the greatest among all resin composites. Dyract AP showed less wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light source as curing unit for composite resin restorations.

요추부 협착증 치료를 위한 극돌기 삽입술의 생체역학적 효과 분석

이희성,첸웬밍,송동률,권순영,이권용,이성재,Lee Hui-Sung,Chen Wen Ming,Song Dong-Ryul,Kwon Soon-Young,Lee Kwon-Yong,Lee Sung-Jae 대한의용생체공학회 2006 의공학회지 Vol.27 No.5

Many types of interspinous distraction devices (IDDs) have been recently developed as an alternative surgical treatment to laminectomy and fusion with pedicle screws for the treatment of the lumbar spinal stenosis (LSS). They are intended to keep the lumbar spine in a slightly flexed posture to relieve pain caused by narrowing of the spinal canal and vertebral foramen. However, their biomechanical efficacies are not well known. In this study, we evaluated the kinematic behaviors and changes in intradiscal pressure (IDP) of the porcine lumbar spine implanted with IDD. For kinematics analysis, five porcine lumbar spines (L2-L6) were used and the IDD was inserted at L4-L5. Three markers (${\phi}{\le}0.8mm$) were attached on each vertebra to define a rigid body motion for stereophotogrammetric assessment of the spinal motion in 3-D. A moment of 7.5Nm in flexion-extension, lateral bending, and axial rotation were imparted with a compressive force of 700N. Then, IDD was implanted at L3-L4. IDPs were measured using pressure transducer under compression (700N) and additional extension moment (700N+7.5Nm). In kinematic behaviors, insertion of IDD resulted in statistically significant decrease 42.8% at the implanted level in extension. There were considerable changes in ROM at the adjacent levels, but statistically insignificant. In other motions, there were no significant changes in ROM as well regardless of levels. IDPs at the surgical level (L3-L4) under compression and extension moment decreased by 12.9% and 18.8% respectively after surgery (p<0.05). At the superiorly adjacent levels, IDPs increased by 19.4% and 12.9% under compression and extension, respectively (p<0.05). Corresponding changes at the inferiorly adjacent levels were 29.4% and 6.9%, but they were statistically insignificant (p>0.05). The magnitude of pressure changes due to IDD, both at the operated and adjacent levels, were far less than the previously reported values with conventional fusion techniques. Our experimental results demonstrated the IDDs can be very effective in limiting the extension motion that may cause narrowing of the spinal canal and vertebral foramens while maintaining kinematic behaviors and disc pressures at the adjacent levels.

반복 회전운동에서 코발트 크롬 합금과 미끄럼 접촉하는 돼지 무릎 관절연골의 접촉압력이 마찰계수 변화에 미치는 영향

김환(Hwan Kim),이권용(Kwon Yong Lee),이영제(Young Ze Lee) 한국트라이볼로지학회 2009 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.25 No.4

In this study, the influence of contact pressure on the variation in coefficients of friction between porcine knee joint cartilage and Co-Cr alloy in a repeat pass sliding motion was investigated. Flat-ended cartilage pin specimens(9 ㎜ diameter, 8 ㎜ long) were prepared from porcine(6 months old) knee joints by a drill-type punch. Friction tests were conducted by using a pin-on-disk type friction tester for an hour in PBS lubricated condition under the contact pressures of 0.5, 1 and 2 ㎫ with 50 ㎜ distance per a cycle at ambient condition. As a result, coefficients of friction increased as the test duration increased for all contact pressures. The maximum coefficients of friction were 0.082,0.06 and 0.098 for 0.5, 1, and 2 ㎫, respectively. It showed that coefficients of friction of porcine knee joint cartilage against Co-Cr alloy depended on the level of contact pressure and related to squeeze film lubrication mechanism.