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강경탁(Kyoung-Tak Kang),손주현(Ju-Hyun Son),전흥재(Heoung-Jae Chun),김호중(Ho-Joong Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Previous reports have introduced the technique of spinous process osteotomy to decompress spinal stenosis, a procedure which aims to afford excellent visualzation while minimizing destruction of tissues not directly involved in the pathologic process. however, bio-mechanically it has not been investigated whether the sacrifice of posterior spinous process might have potential risk of spinal instability or not, even though supra-spinous and inter-spinous ligament are preserved. Therefore the aim of this study is to evaluate the bio-mechanical properties after spinous process osteotomiy, using finite element analysis. In the model of spinous process osteotomy the increase of stress in the disc and segmental rangesof motions were not changed significantly. It is due to the fact that the instability of lumbar spine has been maintained by the two-types of ligaments compared with the prior surgical technique. Therefore, according to the finite element result on this study, these osotetomy was considered to be a clinicallysafe surgical procedure and could not cause the instability of patient.
극돌기 절골술에서 후관절 절제의 정도에 따른 생체 역학적 변화
강경탁(Kyoung-Tak Kang),손주현(Ju-Hyun Son),전흥재(Heoung-Jae Chun),김호중(Ho-Joong Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The aim of this study is to evaluate the biomechanical changes after spinous process osteotomies with different amounts of facetectomy of the lumbar spine and to compare the models with SPO and conventional laminectomy (CL) using finite element model. Intact spine model and two decompression models (L3-4) with SPO were developed. SPO models included three different amounts of facetectomy (25 %, 50%, and 75%). The decompression procedures using spinous process osteotomy has been reported to provide better postoperative stability compared to the conventional laminectomy. However, facetectomy over 50 % is likely to attenuate this advantage.
척추 유합술 후, 인접 분절의 스트레스에 대한 척추경 나사못에 대한 영향
강경탁(Kyoung-Tak Kang),전흥재(Heoung-Jae Chun),손주현(Ju-Hyun Son),김호중(Ho-Joong Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Since the advent of pedicle screw fixation system, posterior spinal fusion has markedly increased. This internal fixation system has been reported to enhance the fusion rates, thereby becoming very popular procedure in posterior spinal arthrodesis. Although some previous studies have shown the complications of spinal instruments removal, i.e. loss of correction and spinal collapse in scoliosis or long spine fusion patients, there has been no study describing the benefit or complications in lumbar spinal fusion surgery of one or two level. In order to clarify the effect of removal of instruments on mechanical motion profile, we simulated a finite element model of instrumented posterolateral fused lumbar spine model, and investigated the change of mechanical motion profiles after the removal of instrumentation.
A validated finite element analysis of nerve root stress in degenerative lumbar scoliosis
Kim, Ho-Joong,Chun, Heoung-Jae,Kang, Kyoung-Tak,Lee, Hwan-Mo,Kim, Hak-Sun,Moon, Eun-Su,Park, Jin-Oh,Hwang, Bo-Hyun,Son, Ju-Hyun,Moon, Seong-Hwan Springer-Verlag 2009 Medical & biological engineering & computing Vol.47 No.6
강경탁(Kyoung-Tak Kang),전흥재(Heoung-Jae Chun),손주현(Ju-Hyun Son),김호중(Ho-Joong Kim),문성환(Seong-Hwan Moon),이환모(Hwan-Mo Lee),김가연(Ka-Yeon Kim) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
Previous studies have introduced the technique of spinous process osteotomy to decompress spinal stenosis, a procedure which aims to afford excellent visualization while minimizing destruction of tissues not directly involved in the pathologic process. However, biomechanically it has not been investigated whether the sacrifice of posterior spinous process might have potential risk of spinal instability or not, even though supra-spinous and inter-spinous ligaments are preserved. Therefore the aim of this study is to evaluate the biomechanical properties after spinous process osteotomy, using finite element analysis. The model of spinous process osteotomy exhibited no significant increase in disc stress or change in segmental range of motion. It is due to the fact that the instability of lumbar spine has been maintained by the two-types of ligaments compared with the prior surgical technique. Therefore, according to the finite element result on this study, this osotetomy was considered to be a clinically safe surgical procedure and could not cause the instability of the lumbar spine.
요추 유합술 후 인접 분절의 조기 퇴행성 변화 요인에 대한, 생체 역학적 분석
강경탁(Kyoung-Tak Kang),손주현(Ju-Hyun Son),전흥재(Heoung-Jae Chun),김호중(Ho-Joong Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The aim of this study is to investigate the change in biomechanical milieu following removal of pedicle screws or removal of spinous process with posterior ligament complex in instrumented single level lumbar arthrodesis. Four scenarios of L3-4 lumbar fusion were simulated: posterolateral fusion (PLF) at L3-4 using pedicle screw system with preservation of PLC (WiP c P), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system with preservation of PLC (WoP c P), L3-4 using pedicle screw system without preservation PLC (WiP s P), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system without preservation of PLC (WoP s P). For these models, we investigated the range of motion in all segments under moments. This study demonstrated that removal of pedicle screw system and preservation of PLC after complete lumbar spinal fusion could reduce the stress of adjacent segments synergistically and might have beneficial effects in preventing ASD.
Kang, Kyoung-Tak,Kim, Ho-Joong,Son, Juhyun,Yeom, Jin S.,Chun, Heoung-Jae Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.1
In this study finite element model of the human lumbar spinal segments (L2-L5) was developed to parametrically examine the stiffness of a dynamic stabilization device and its influence on the mobility of adjacent intervertebral segments. Five models were analyzed and compared: (1) a lumbar spine with intact discs, a reference; (2) a fused spine with a fixation device following interbody fusion and total laminectomy; (3) a spine stabilized with a dynamic stabilization device following total laminectomy; and (4) an additional vertically parallel paired dynamic posterior fixator and paired rigid fixator implemented at levels L3-L5. The disc pressure on the adjacent segments in the fused spine was greater than that of the intact spine, but the disc pressure of the dynamically stabilized spine was similar to that of the intact spine. The use of dynamic stabilization devices restored functionality more closely to that of the intact spine compared to the fused spine. The stiffness values utilized in the device were determined to be important design parameters for manufacturing dynamic stabilization devices.
웨이브릿 변환을 이용한 도플러 신호의 순간 주파수 추정
손중탁,이승훈,박길흠,Son Joong-Tak,Lee Seung-Houn,Park Kil-Houm 대한전자공학회 2005 電子工學會論文誌-SP (Signal processing) Vol.42 No.3
도플러 신호의 순간 주파수는 탄과 표적간의 상대속도, 이격거리 등의 정보를 얻는데 사용된다. 순간 주파수 추정을 위해 주로 사용되는 방법인 단구간 퓨리에 변환은 시간 및 주파수의 영역에서 고정된 크기의 창을 가지므로 광대역의 신호 특히, 주파수가 급격하게 변하는 신호에 대한 순간 주파수 추정에서는 많은 오차가 발생한다. 본 논문에서는 시간 및 주파수의 영역에서 창의 크기를 적응적으로 변화시킬 수 있는 연속 웨이브릿 변환에 기반한 도플러 신호의 순간 주파수를 추정하는 방법을 제안한다. 제안한 방법은 고주파수 영역에서는 좁은 창, 저주파수 영역에서는 넓은 창을 적용하여 시간에 따른 주파수의 변화에 무관하게 순간 주파수를 추정한다. 모의실험과 실제 실험을 통한 성능평가 결과 제안한 방법이 기존의 단구간 퓨리에 변환 방법에 비해 우수함을 확인하였다. Instantaneous Frequency(IF) of Doppler signals is used to get the information of relative velocity and miss distance between a missile and the corresponding target. Though Short-Time Fourier Transform(STFT) is mainly used to estimate IF, it has many errors in wide band signals where frequency changes sharply. Because it has a fixed window in time and frequency axes. This paper deals with IF estimation of Doppler signal using a Continuous Wavelet Transform(CWT) which has adaptive window in time and frequency axes. The proposed method is able to estimate IF regardless of frequency changes because it has a narrow window in high frequency band and a wide window in low frequency band. The experimental results demonstrate that the proposed method outperforms STFT in estimating IF.
손중탁,이승훈,박길흠,Son, Joong-Tak,Lee, Seung-Houn,Park, Kil-Houm 한국군사과학기술학회 2005 한국군사과학기술학회지 Vol.8 No.2
Instantaneous frequency of doppler signals is used to get the information of the relative velocity and the miss distance between a missile and a corresponding target. In this paper, we have performed time-frequency analysis and instantaneous frequency estimation with Short Time Fourier Transform(STFT), Wigner Ville Distribution(WVD) and Continuous Wavelet Transform(CWT) about the doppler signals generated by moving targets. Performance evaluation was performed using simulated doppler signals generated by a single moving target and two moving targets. From the results of the time-frequency analysis, we found that WVD method was the most efficient instantaneous frequency estimator among the three methods. But in case of two moving targets, WVD method got cross talks and CWT method got oscillation when two doppler frequencies were close to each other.
Li, Quan You,Kim, Ho-Joong,Son, Juhyun,Kang, Kyoung-Tak,Chang, Bong-Soon,Lee, Choon-Ki,Seok, Hyun Sik,Yeom, Jin S. Elsevier 2017 Computers in biology and medicine Vol.89 No.-
<P><B>Abstract</B></P> <P><B>Background</B></P> <P>There are no studies about the biomechanical analysis of lumbar decompression surgery in relation to degenerative changes of the lumbar spine. Therefore, the purpose of this study was to compare, by using finite element (FE) analysis, the biomechanical changes of the lumbar spine in terms of annulus stress and nucleus pressure after two different kinds of lumbar decompression surgery in relation to disc degenerative changes.</P> <P><B>Methods</B></P> <P>The validated intact and degenerated FE models (L2-5) were used in this study. In these two models, two different decompression surgical scenarios at L3-4, including conventional laminectomy (ConLa) and the spinous process osteotomy (SpinO), were simulated. Therefore, a total of six models were simulated. Under preloading, 7.5 Nm moments of flexion, extension, lateral bending, and torsion were imposed. In each model, the maximal von Mises stress on the annulus fibrosus and nucleus pressure at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) were analyzed.</P> <P><B>Results</B></P> <P>The ConLa model and disc degeneration model demonstrated a larger annulus stress at the decompression level (L3-4) under all four moments than were seen in the SpinO model and healthy disc model, respectively. Therefore, the ConLa model with moderate disc degeneration showed the highest annulus stress at the decompression level (L3-4). However, the percent change of annulus stress at L3-4 from the intact model to the matched decompression model was less in the moderate disc degeneration model than in the healthy disc model.</P> <P><B>Conclusions</B></P> <P>Although the ConLa model with moderate disc degeneration showed the highest annulus stress, the degenerative models would be less influenced by the decompression technique.</P>