최적 단면 치수를 가지는 복합재료 중공빔의 설계

전흥재,박혁성,최용진,Chun Heong-Jae,Park Hyuk-Sung,Choi Yong-Jin 한국전산구조공학회 2005 한국전산구조공학회논문집 Vol.18 No.3

본 연구에서는 휠체어의 경량화를 위해 기존의 강관으로 제작된 휠체어를 피로파괴 및 손상에 강하고 방진 특성이 우수하며 유지 및 보수가 용이한 복합재료 중공빔으로 구성된 복합재료 휠체어로 대체하기 위하여 복합재료 중공빔 이론과 유전자 알고리즘을 적용하여 최적화된 등가 강성을 가지는 복합재료 중공빔의 최적의 단면 치수를 제시하였다. 제시한 최적의 단면치수를 가지는 복합재료 중공빔으로 구성된 휠체어 전체 구조에 Tsai-Wu 파손이론을 이용해 과하중이 가해지는 경우에 대하여 구조해석을 수행한 결과, 휠체어의 파손 유무를 나타내는 Makimum Tsai-Wu Failure Criteria Index가 파손이 발생하는 1.00보다 현저히 낮은 $0.192\times10^{-3}$을 나타내고 있음을 알 수 있었다. 또한 기존의 강관을 동일한 강성을 가지는 복합재료 증공빔으로 대체하였을 경우 중공빔 중량을 최대 45%감소하는 효과를 얻을 수 있음을 확인할 수 있었다. In this study, the problem formulation and solution technique using genetic algorithms for design optimization of laminate composite cylindrical beam section are presented. The hollow cylindrical beams we usually used in the wheel chair. If the weight of wheel chair is reduced, it will lead to huge improvement in passenger's mobility and comfort. In this context, the replacement of steel by high performance and light weight composite material along with optimal design will be a good contribution in the process of weight reduction of a wheel chair. An artificial genetics approach for the design optimization of hollow cylindrical composite beam is presented. On applying the genetic algorithm, the optimal dimensions of hollow cylindrical composite beams which have equivalent rigidities to those of corresponding hollow cylindrical steel beams are obtained. Also structural analysis is conducted on the entire wheel chair structure incorporating Tsai-Wu failure criteria. The maximum Tsai-Wu failure criteria index is $0.192\times10^{-3}$ which is moth less than value of 1.00 indicating no failure is observed under excessive loading condition. It is found that the substitution of steel by composite material could reduce the weight of wheel chair up to 45%.

굴곡진 보강섬유가 복합재료의 기계적 특성에 미치는 영향과 일정한 보강섬유의 굴곡비를 가지는 복합재료의 성형방법에 관한 연구

전흥재(H.- J. Chun),신재윤(J. Y. Shin),최흥섭(H. S. Choi) Korean Society for Precision Engineering 1999 한국정밀공학회지 Vol.16 No.9

망막 회복을 위한 줄기세포 및 조직공학의 연구동향

박상준 ( Sang Jun Park ),천명훈 ( Myung Hoon Chun ),전흥재 ( Heung Jae Chun ),김천호 ( Chun Ho Kim ) 한국조직공학과 재생의학회 2009 조직공학과 재생의학 Vol.6 No.4

The retinal disorder in which it shows up while an age gives is caused by a heredity and altitude myopia, a debit, and etc. and it causes the blind. Although retinal disorder is not disease in which fatal disease leads, in including a diabetes, and etc, the retina disease in which it can become with provoke is the trend that recently it is drastically increased along with the increment of the population of old people according to the change of an industrialization and dietary life. However, as to the current retinal disorder, there is a limit. For this reason, the medical treatment of the method in which directly transplant the nerve cells or the glial cells differentiated from the stem cell and retina precursor cell into retina, and the tissue engineered therapy of the neural retina in which it implants into a retina to the tissue engineering technique in which use these cells and biomaterials have been studied. The current review looks into clinical methods and studies on cell and tissue engineering therapy for the retinal disorder.

키토산/히알루론산 비드 지지체에서 히알루론산이 연골세포의 부착 및 성장에 미치는 영향

박상준 ( Sang Jun Park ),유성미 ( Seong Mi Yu ),천명훈 ( Myung Hoon Chun ),전흥재 ( Heung Jae Chun ),김천호 ( Chun Ho Kim ) 한국조직공학·재생의학회 2009 조직공학과 재생의학 Vol.6 No.4

In this study, the chitosan/hyaluronic acid bead scaffolds having open macropores without any surface skin layer were prepared from phase separation process and the morphology of the beads was analyzed by scanning electron microscopy(SEM). To study of effect of hyaluronic acid on attachment and proliferation of chondrocyte on chitosan/hyaluronic acid bead scaffolds, chondrocytes isolated from rabbit costal cartilage were cultured on the beads. The cellular viability and proliferation were assayed by cell counting kit-8. The cell attachment and distribution in the beads were also analyzed by SEM and safrain-O/fast green staining after 14 and 28 days culture. The chondrocytes were more proliferated in outside than inside of the chitosan bead scaffolds, while proliferated uniformly both outside and inside of the chitosan/hyaluronic acid bead scaffolds. The round shape of chondrocytes as phenotype was also exhibited in chondrocyte culture on the beads. Therefore the new prepared chitosan/hyaluronic acid bead scaffolds are suitable for tissue engineering application.

골시멘트 특성 및 스템 형상에 따른 시멘트 타입 인공관절의 생체역학적 평가

박흥석,전흥재,윤인찬,이문규,최귀원,Park, H.S.,Chun, H.J.,Youn, I.C.,Lee, M.K.,Choi, K.W. 대한의용생체공학회 2008 의공학회지 Vol.29 No.3

The total hip replacement (THR) has been used as the most effective way to restore the function of damaged hip joint. However, various factors have caused some side effects after the THR. Unfortunately, the success of the THR have been decided only by the proficiency of surgeons so far. Hence, It is necessary to find the way to minimize the side effect caused by those factors. The purpose of this study was to suggest the definite data, which can be used to design and choose the optimal hip implant. Using finite element analysis (FEA), the biomechanical condition of bone cement was evaluated. Stress patterns were analyzed in three conditions: cement mantle, procimal femur and stem-cement contact surface. Additionally, micro-motion was analyzed in the stem-cement contact surface. The 3-D femur model was reconstructed from 2-D computerized tomography (CT) images. Raw CT images were preprocessed by image processing technique (i.e. edge detection). In this study, automated edge detection system was created by MATLAB coding for effective and rapid image processing. The 3-D femur model was reconstructed based on anatomical parameters. The stem shape was designed using that parameters. The analysis of the finite element models was performed with the variation of parameters. The biomechanical influence of each parameter was analyzed and derived optimal parameters. Moreover, the results of FE A using commercial stem model (Zimmer's V erSys) were similar to the results of stem model that was used in this study. Through the study, the improved designs and optimal factors for clinical application were suggested. We expect that the results can suggest solutions to minimize various side effects.

다양한 설계변수를 고려한 수직하중을 받는 일체형 임플랜트의 최적설계

최재민,전흥재,이수홍,한종현,Choi Jae-Min,Chun Heoung-Jae,Lee Soo-Hong,Han Chong-Hyun 대한치과보철학회 2006 대한치과보철학회지 Vol.44 No.2

Statement of problem: The researches on the influence of design variables on the stress distribution in cortical and trabecular bones and on optimal design for implant system were limited. Purpose: The purpose of this study is to identify the sensitivities of design parameters and to suggest the optimal parameters for designing the onebody type implant system. Material and methods: Stresses arising in the implant system were obtained by finite element analysis using a three dimensional model. An onebody type implant system[Oneplant (Warrantec. Co. Ltd., Korea)] was considered in this study. Vortical load(150 N) was applied on the top of the abutment along the axial direction. The initial design variables set for sensitivity analysis were radius of fixture, numbers of micro thread, numbers of power thread, height of micro thread, future length, tapered angle of future, inclined angle of thread, width of micro thread and width of power thread. The statistical technique of Design of Experiments(DOE) was applied tn the simulation model to deduce effective design parameters on stress distributions in bones. The deduced design parameters were incorporated into a fully automated design tool which is coupled with the finite element analysis and numerical optimization to determine the optimal design parameters. Results: 1. The result of sensitivity analysis showed six design variables - radius of future, tapered angle of fixture, inclined angle of thread, numbers of power thread, numbers of micro thread and height of micro thread - were more influential than the others. 2. The optimal values of design variables can be deduced by coupling finite element analysis (FEA) and design optimization tool(DOT).

치과용 골유착성 임플랜트 고정체 형상의 응력 분산에 관한 연구

한종현,전흥재,정신영,허성주,최용창,정종평,구영,류인철,김명호,Han, Chong-Hyun,Chun, Hung-Jae,Jung, Sin-Young,Heo, Seong-Joo,Choi, Yong-Chang,Chung, Chong-Pyung,Ku, Young,Ryu, In-Chul,Kim, Myung-Ho 대한치과보철학회 2000 대한치과보철학회지 Vol.38 No.4

Finite element analyses were performed to study effects on stress distribution generated in jaw bone for various shapes of dental implants: plateau type, plateau with small radius of curvature, triangular thread screw type in accordance with ISO regulations and square thread screw filleted with small radius partially. It was found that square thread screw filleted with small radius was more effective on stress distribution than other dental implants used in analyses. Additional analyses were performed on the implant with square thread screw filleted with small radius for very-ing design parameters, such as the width of thread end, the height of the thread of the implant and load direction, to determine the optimum dimensions of the implant. The highest stress concentration occurred at the region in jaw Pone adjacent to the first thread of the implant. The maximum effective stress induced by a 15 degree oblique load of 100 N was twice as high as the maximum effective stress caused by an equal amount of vertical load. Stress distribution was more effective in the case when the width of thread end and the height of thread were p/2 and 0.46p, respectively, where p is the pitch of thread. At last, using tensile force calculated from the possible insert torque without breading bone thread, finite element analysis was performed on the implant to calculate pre-stress when the primary fixation of the implant was operated in jaw bone. The maximum effective stress was 136.8 MPa which was proven to be safe.

임프란트의 상부구조물 형상과 하중조건에 따른 3차원 유한요소해석을 이용한 하악골의 응력분포에 관한 연구

신하식,전흥재,한종현,이수홍,Shin Ha-Shik,Chun Heoung-Jae,Han Chong-Hyun,Lee Soo-Hong 대한치과보철학회 2003 대한치과보철학회지 Vol.41 No.5

Statement of problem : There are many studies focused on the effect of shape of futures on stress distribution in the mandibular bone. However, there are no studies focused on the effect of the abutment types on stress distribution in mandibular bone. Purpose : The purpose of this study is to investigate the effect of three different abutment types on the stress distributions in the mandibular bone due to various loads by performing finite element analysis. Material and method : Three different implant systems produced by Warantec (Seoul, Korea), were modeled to study the effect of abutment types on the stress distribution in the mandibular bone. The three implant systems are classified into oneplant (Oneplant, OP-TH-S11.5). internal implant (Inplant, IO-S11.5) and external implant (Hexplant, EH-S11.5). All abutments were made of titanium grade ELI. and all fixtures were made of titanium grade IV. The mandibular bone used in this study is constituted of compact and spongeous bone assumed to be homogeneous, isotropic and linearly elastic. A comparative study of stress distributions in the mandibular bone with three different types of abutment was conducted. Results : It was found that the types of abutments have significant influence on the stress distribution in the mandibular bone. It was due to difference in the load transfer mechanism and the size of contact area between abutment and fixture. Also the maximum effective stress in the mandibular bone was increased with the increase of inclination angle of load. Conclusion : It was concluded that the maximum effective stress in the bone by the internal implant was the lowest among the maximum effective stresses by other two types.

치조골흡수 유형에 따른 치근단 절제술의 수술적 평가에 관한 연구

홍형택,전흥재,Hong, Hyoung Taek,Chun, Heoung Jae 한국전산구조공학회 2013 한국전산구조공학회논문집 Vol.26 No.6

본 논문에서는 치조골의 흡수 유형에 따른 치근단 절제술의 수술적 평가를 수행하였다. 유한요소해석이 사용되었으며 CT 이미지를 통하여 동양 성인 여성의 상악 중절치의 3D 모델을 사용하였다. 연구에는 상악중절치의 정상저작하중조건이 적용되었다. 치조골 흡수 유형에 따른 치근 절제술의 평가를 위해 정상모델과 함께 치조골의 전체적 흡수 모델, 순측 흡수 모델 및 설측 흡수 모델을 비교하였다. 이에 따라 설측 치조골 흡수의 영향은 순측 치조골의 흡수에 비해 치아의 유지 안정성에 미치는 영향이 작음을 확인하고, 설측 치조골 흡수로 인해 치근이 노출된 환자를 대상으로 한 치근 절제술의 위험 가능성을 제시하였다. The surgical evaluation of the apicoectomy with various types of alveolar bone resorption was conducted in current study. The apicoectomy is the common and important treatment in endodontics. Finite element analysis was used for evaluation. The 3D solid model of the maxillary central incisor was reconstructed using CT images of a mature Asian female. Loading and boundary conditions were simulated in the normal mastication of maxillary central incisor. For evaluation of apicoectomy, lingual, labial and entire alveolar bone resorption models were developed. In the results, lingual alveolar bone resorption did not significantly influence stress distribution pattern of root dentin and labial alveolar bone had an important role for supporting structural stability in tooth system.

임플랜트의 체결방식에 따른 초기조임력에 의한 응력분포 및 전하중에 관한 연구

이범현,전흥재,이수홍,한종현,Lee Bum-Hyun,Chun Heoung-Jae,Lee Soo-Hong,Han Chong-Hyun 대한치과보철학회 2006 대한치과보철학회지 Vol.44 No.2

Statement of problem: One of common problems associated with single teeth dental implant prosthetic is the loosening of screws that retain the implants. Purpose: The maintenance of screw joint stability is considered a function of the preload achieved in the screw when the suggested initial tightening torque is applied. The purpose of this study was to investigate acquired preload after initial clamping torque for estimating screw joint stability. Material and methods: A comparative study on the effect of initial clamping of two types of implant systems with different connections was conducted Three dimensional non-linear finite element analysis is adopted to compare the characteristics of screw preloads and stress distributions between two different types of implant systems composed with abutment, screw, and fixture under the same loading and boundary conditions. Results: 1. When the initial clamping torque of 32Ncm was applied to the implant systems, all types of implants generated the maximum effective stress at the first helix region of screw. 2. Morse taper connection types of implants generate lower stress distributions compared to those by butt joint connection types or implants due to large contact surface between abutment and fixture. 3. The internal types of implant systems with friction grip type implant systems have higher resistance to screw loosening than that of the external types of implant systems since the internal types of implant systems generated larger preload than that generated by the external types for the same tightening moments.