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쾌속조형시스템을 이용한 생체 조직 재생용 지지체 제작과 특성분석
김지웅(Jiwoong Kim),박고은(Koeun Park),이준희(Jun-Hee Lee),박수아(Sua Park),김완두(Wandoo Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
The purpose of tissue engineering is to repair or replace damaged tissues or organs by a combination of cells, scaffold, suitable biochemical and physio-chemical factors. Among the three components, the biodegradable scaffold plays an important role in cell attachment and migration. In this study, we designed 3D porous scaffold by Rapid Prototyping (RP) system and fabricated layer-by-layer 3D structure using Polycarprolactone (PCL) - one of the most flexible biodegradable polymer. Furthermore, the physical and mechanical properties of the scaffolds were evaluated by changing the pore size and the strand diameter of the scaffold. We changed nozzle diameter (strand diameter) and strand to strand distance (pore size) to find the effect on the mechanical property of the scaffold. And the surface morphology, inner structure and storage modulus of PCL scaffold were analyzed with SEM, Micro-CT and DMA.
다중노즐 전기방사공정을 이용한 PCL/HA 나노섬유 제작
김지웅(Jiwoong Kim),박종하(Jongha Park),윤현(Hyun Yoon),손준곤(Jungon Son),박고은(Koeun Park),박수아(Sua Park),김완두(Wandoo Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Electrospinning is the process using electrical charge to distort a pendant droplet of polymer solution into a fine fiber to be deposited onto a target substrate. The merits of electrospinning are the fiber fabrication of small diameter and good mechanical properties. This means the nanofiber formation with high surface area to volume ratio and the ability to control pore size. Nanometer-diameter nanofibers have the potential applications of filter membranes, biomedical device, wound dressing materials, artificial organs, nanoelectronics, nano-composites, and protective clothing. To fabricate the uniform thickness and oriented morphology of PCL/HA nanofiber, multi-nozzle spinnerets were manufactured with rotatable grounded target collector in this study. We measured SEM observation, mechanical property, and contact angle of PCL/HA nanofiber.
우창수(Changsu Woo),김완두(Wandoo Kim),최성신(Sungshin Choi) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
The material characteristics and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. This paper discusses the material test and accelerated heat aging test were carried out to predict the useful life of NBR and EPDM rubber mount for compression motor which is used in refrigerator. In order to investigate the heat-aging effects on the material properties, the crosslink density, modulus at 100%, stress-strain curves were obtained from the results of uniaxial and equi-biaxial tensile test. Compression set results changes as the threshold are used for assessment of the useful life and the time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. The useful life at variable temperatures are obtained in the Arrhenius relationship
우창수(Changsu Woo),김완두(Wandoo Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. Fatigue life prediction methodology of the rubber component was proposed by incorporating the finite element analysis and fatigue damage parameter from fatigue test. Finite element analysis of 3D dumbbell specimen and engine mount rubber component were performed based on a hyper-elastic material model determined from material test. The Green-Lagrange strain at the critical location determined from the FEM was used for evaluating the fatigue damaged parameter of the natural rubber. Fatigue life of the rubber component are predicted by using the fatigue damage parameter at the critical location. Predicted fatigue lifes of engine mount rubber component agreed fairly well the experimental fatigue lives.
우창수(Changsu Woo),김완두(Wandoo Kim),김영길(Younggil Kim),신외기(Waegi Shin),이성훈(Seonghoon Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. Recently, the design, analysis and evaluation technology was required to achieve the high quality, fidelity, reliability of rubber products. However, rubber manufacturing companies of our country have uesd the method of trial and error and experience in the process of a compound mixing, manufacturing and improvement of rubber properties. The objectives of this study are to establish the test methods of rubber material and to make the database of rubber material properties and to evaluate the performance of rubber components and to construct the prediction system of fatigue life. Fatigue lifetime prediction methodology of the rubber component was proposed by incorporating the finite element analysis and fatigue damage parameter from fatigue test.
우창수(Changsu Woo),김완두(Wandoo Kim),김완수(Wansoo Kim),권재도(Jaedo Kwon) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The interest of the fatigue life of rubber components such as engine mounts is increasing according to the extension of warranty period of the automotive components This paper discusses a fatigue life prediction of the 3-dimensional dumbbell specimens and rubber components considering the effects of maximum strain. Displacement controlled fatigue life tests were performed using specimens with different levels of maximum strain and various hardness. The basic mechanical properties test and the fatigue test of rubber specimen were executed. A procedure to predicted the fatigue life of vulcanized natural rubber components based on the maximum strain method was proposed, and then this curve was in good agreement with fatigue test data less than 200% error range.
우창수(Changsu Woo),김완두(Wandoo Kim),권재도(Jaedo Kwon) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Fatigue life prediction methodology of the vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter determined from the fatigue tests. Nonlinear finite element analysis of the 3-D dumbbell specimen of natural rubber was performed based on a hyperelastic material model determined from the tension, compression and shear tests. The Green-Lagrange strain at the critical location determined from the FEA was used for evaluating the fatigue damage parameter of natural rubber. Fatigue tests were formed using the 3-D dumbbell specimens with different levels of maximum strain and various hardness. Fatigue life curves can be effectively represented by a following single function using the Green-Lagrange strain. Predicted fatigue lives of the rubber component agreed fairly well the experimental fatigue lives.