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이재호(Jae Ho Lee),윤호주(Ho Ju Yun),안명주(Myung Ju Ahn),김태화(Tae Hwa Kim),김성윤(Seong Yoon Kim),김목현(Mok Hyun Kim) 대한내과학회 1987 대한내과학회지 Vol.33 No.6
N/A We compared the genetic distances between the Far-Eastern populations to investigate the relationship between them. Sampled regions were nine countries. The method was microcytotoxicity of NIH by use of antisera received from 3rd AOHWS. We used the results of HLA frequency published from 3rd AOHWS. The genetic distances are calculated by Nei et all equation. The following are the results. 1) The nearest GD with Southern Korean is Japanese. Historically, this was reflected of close relationship between Korean and Japanese. 2) There were near GD between North Chinese neigh-boring populations. This thought that North Chinese had a close contact with neighboring countries. 3) However, this should be confirmed again after subdivision of regions, and also be required of many investigations to cover the defect of this study.
척추경 나사못의 디자인이 고정력 및 구동 토크에 미치는 영향 분석: 이중 나사 및 이중 피치 나사
최선각,차은종,김경아,안윤호,Choi, Sun-Gak,Cha, Eun-Jong,Kim, Kyung-Ah,Ahn, Yoon-Ho 대한의용생체공학회 2018 의공학회지 Vol.39 No.3
One of the most common problems with pedicle screw system is pullout of the screw. This study was performed to evaluate the pullout strength and driving torque of newly designed pedicle screws. The design of three type screws were standard pedicle screw, which had single lead threaded and single pitched design (Type A), single pitched and dual lead threaded pedicle screw (Type B), dual pitched and dual lead threaded pedicle screw (Type C), respectively. The tests were performed in accordance with the ASTM standards using polyurethane (PU) foam blocks. There was no significant difference in pullout strength among three types of screw. Type B and Type C exhibited higher insertion torque and removal torque than Type A, respectively (p<0.05). Pedicle screws newly developed with dual pitched and dual lead threaded design showed higher driving torque without decrease in pullout strength compared to the standard pedicle screw and could be inserted more rapidly with the same number of revolutions.
척추의 해부학적 요소를 고려한 척추경 나사못 디자인의 Pullout 특성 연구
유경주,박광민,안경기,안윤호,Yoo, Kyeong-Joo,Park, Kwang-Min,Ahn, Kyoung-Gee,Ahn, Yoon-Ho 대한의용생체공학회 2021 의공학회지 Vol.42 No.1
Recently, various types of pedicle screws have been developed considering the anatomical structure of the spine. The purpose of this study was to evaluate the pullout stiffness and strength of two types of commercial pedicle screws. The design of two type screws were single pitched thread (ST) pedicle screw and dual pitched thread (DT) pedicle screw, respectively. The tests were conducted in accordance with the ASTM standards using polyurethane (PU) test blocks which has anatomical structure of the spine. There was no significant difference in pullout stiffness between two types of screw. However, DT exhibited higher pullout strength than ST (p<0.05). Pedicle screw with dual pitched thread showed higher pullout strength without decrease in pullout stiffness compared to the standard pedicle screw. In conclusion, dual pitched thread design of the pedicle screw is considered to be more suitable than the single pitched thread for the anatomical structure of the spine.
Chen Wen-Ming,Ahn Yoon-Ho(안윤호),Lee Hui-Sung(이희성),Moon Soo-Jung(문수정),Lee Kwon-Yong(이권용),Lee Sung-Jae(이성재) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The endplate that lies between the vertebral body and intervertebral disc is a structure of significant physiological importance. However, mechanically the end-plate appears to be a “weak link” and its fracture pattern presents an age-related phenomenon. In current study, the effects of simulated degenerative changes in the lumbar disc and vertebral body on the endplate were examined using finite element (FE) analysis. For this purpose, an intact lumbar functional spinal unit (FSU) of L3-4 FE model was constructed and another three degenerative models were made by modifying the intact one. A mildly degenerated disc was simulated by removing the hydrostatic capacities of the nucleus and making the disc stiffer than a normal one. The severe degenerated disc, made by “nuclotomy”, was assumed to be void of nucleus. The possible alterations in bone quality due to osteoporosis were simulated by adjusting the corresponding material properties of bony structures. Under axial compression of 2000N, compared to the intact case, the model with “stiffer” disc showed an 82.4% decrease in tensile stress in posterior region, a 22.5% increase in compression in the mid region of the endplate respectively; while compressive stress generated anteriorly. The “nucleotomy” case showed reversed stress states in all regions of the endplate correspondingly. As to the “osteoporosis” model, there were 32% and 50.6% increases in the tensile stress in posterior and anterior regions of the endplate respectively. Based on these results, the failure patterns could be predicted. We concluded that the stress and strain distributions in endplate under axial loading were highly dominated by its adjacent structures. Both the degenerated disc and osteoporosis may have a pronounced impact on the structural failure of the endplate, and the possible fracture patterns predicted by FE model might be used as references for the clinical assessment of the failure mechanism of the endplate.