역학적 강도 분석을 이용한 저강도 초음파의 조사 부위의 골다공증 골절 방지 효과 평가

우대곤,김치훈,박지형,고창용,김한성,김진만,김상희,임도형,Woo, Dae-Gon,Kim, Chi-Hoon,Park, Ji-Hyung,Ko, Chang-Young,Kim, Han-Sung,Kim, Jin-Man,Kim, Sang-Hee,Lim, Do-Hyung 대한의용생체공학회 2009 의공학회지 Vol.30 No.2

Purpose: The aim of present study is to evaluate a possibility of clinical application for the effect of low intensity ultrasound stimulation (LIUS) in mechanical characteristics of bone on osteoporotic fractures prevention. Materials and Methods: Eight virgin ICR mice (14 weeks old, approximate weight 25g) were ovariectomized (OVX) to induce osteoporosis. The right hind limbs were then stimulated with LIDS (US Group), whereas left hind limbs were not stimulated (CON Group). Both hind limbs of all mice were scanned by in-vivo micro-CT to acquire two-dimensional (2D) images at 0 week before stimulation and 3 weeks and 6 weeks after stimulation. Three-dimensional (3D) finite element (FE) models generated by scanned 2D images were used to determine quantitatively the effect of LIUS on strength related to bone structure. Additionally, distributions of Hounsfield units and elastic moduli, which are related to the bone quality, for the bones in the US and CON groups were determined to analyze quantitatively a degree of improvement of bone qualities achieved by LIUS. Results: The result of FE analysis showed that the structural strength in US Group was significantly increased over time (p<0.05), while that in CON Group was statistically constant over time (p>0.05). High values of Hounsfield units obtained from voxels on micro-CT images and high values of elastic moduli converted from the Hounsfield units were dominantly appeared in US Group compared with those in CON Group. Conclusion: These finding indicated that LIUS would improve the mechanical characteristics of osteoporotic bone via the effects of bone structure (bone strength) and quality (Hounsfield unit and elastic modulus). Therefore, the LIUS may decrease effectively the risk of osteoporotic fracture in clinics.

인체 흉추 해면골의 영역별 형태학적 및 기계적 특성 연구

이태우(Tae Woo Lee),우대곤(Dae Gon Woo),고창용(Chang-Young Ko),김한성(Han-Sung Kim) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.1

This study analyzed the regional morphological and mechanical characteristics of vertebrae by using micro-computed tomography (micro-CT) and micro finite element analysis (FEA). For the present study, the 12<SUP>th</SUP> human thoracic vertebral bones (an 85-years female and a 48-years male) were used. These were scanned by using micro-CT. Structural parameters were evaluated from the acquired 2D image data for fifteen 4×4㎟ regions (five regions in respective layers of superior, middle and inferior part) in the thoracic vertebral trabecular bones. 4×4×4㎣ cubic finite element models of each regions were created at 70μm voxel resolution to investigate effective modulus (E<SUP>†</SUP>). The present study indicated that there were significant differences in morphological and elastic mechanical characteristics of each region. There are close relationship between effective modulus and structural model index (SMI) in the bone of the 48-years male and between effective modulus and bone volume fraction (BV/TV) in the bone of the 85-years female. In addition, the effective modulus of central regions is about 80% stiffer than that of lateral regions at transverse plane. These findings may be likely to explain the previous result that a change of loading distribution of the vertebral trabecular bones is caused by spinal curvature and nucleus pulpous degeneration of the intervertebral disc.

유한차분법을 이용한 기능성 위장 장애 진단용 초음파 시스템의 개발

박원필(Won Pil Park),우대곤(Dae Gon Woo),고창용(Chang Yong Ko),이균정(Qyoun Jung Lee),이용흠(Yong Heum Lee),최서형(Seo Hyoung Choi),신태민(Tae Min Shin),김한성(Han Sung Kim),임도형(Dohyung Lim) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.9

The disaster from functional gastrointestinal disorders(FGID) has detrimental impact on the quality of life of the affected population. There are, however, rare diagnostic methods for FGID. Our research group identified recently that the gastrointestinal tract well of the patients with FGID became more rigid than that of healthy people when palpating the abdominal regions overlaying the gastrointestinal tract. The objective of the current study is, therefore, to identify feasibility of a diagnostic system for FGID based on ultrasound technique, which can quantify the characteristics above. Two-dimensional finite difference(FD) models(one normal and two rigid models) were developed to analyze the reflective characteristic(displacement) on each soft-tissue layer responded after application of ultrasound signals. Based on the results from FD analysis, the ultrasound system for diagnosis of the FGID was developed and clinically tested via application of it to 40 human subjects with/without FGID who were assigned to Normal and Patient Groups. The results from FD analysis showed that the maximum displacement amplitude in the rigid models(0.12 and 0.16) at the interface between the fat and muscle layers was explicitly less than that in the normal model(0.29). The results from actual specimens showed that the maximum amplitude of the ultrasound reflective signal in the rigid models(0.2±0.1Vp-p) at the interface between the fat and muscle layers was explicitly higher than that in the normal model(0.1±0.0Vp-p). Clinical tests using our customized ultrasound system showed that the maximum amplitudes of the ultrasound reflective signals near to the gastrointestinal tract well for the patient group(2.6±0.3Vp-p) were generally higher than those in normal group(0.1±0.2Vp-p). These findings suggest that our customized ultrasound system using the ultrasound reflective signal may be helpful to the diagnosis of the FGID.

난소 절제술을 시행한 흰쥐 등뼈의 해면골과 피질골의 구조적 특성 추적관찰 및 기계적 특성 분석

고창용(Chang Yong Ko),우대곤(Dae Gon Woo),이태우(Tae Woo Lee),김한성(Han Sung Kim),이법이(Beob Yi Lee),탁계래(Gye Rae Tack) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.1

This study investigated changes of mechanical characteristics of the trabecular and cortical bone in the lumbar vertebrae of the ovariectomised (OVX) rat. In previous researches, there were many studies for morphology of osteoporotic bones based on Micro-Computed Tomography (Micro-CI'), However, there were few studies for detecting and tracking changes of mechanical characteristics of the trabecular and cortical bone in the lumbar vertebrae of the OVX rat. For this study, the 4th lumbar of the OVX rat (female Sprague-Dawley) was utilized as a specimen. An OVX rat was scanned at week 0 Oust before surgery), at week 4, and week 8 after surgery. Micro-finite element (μ-FE) analysis was used to investigate mechanical characteristics of the trabecular and cortical bone in the lumbar vertebrae for an OVX rat. When the OVX rat (at week 8) was compared with the OVX rat (at week 0), the structural modulus of cortical and trabecualr bone was decreased by 52% and 99%, respectively. This study showed the change of mechanical characteristics of cortical bone as well as trabecular bone of an OVX rat. Detecting and tracking changes of mechanical characteristics could greatly contribute to an experiment test for the trabecular and cortical bone in the lumbar vertebrae of an OVX rat by using In-vivo Micro-CT.

원자힘 현미경을 이용한 성장기 흰쥐의 호르몬 결핍이 무릎 연골세포에 미치는 영향 분석

김치훈 ( Chi Hoon Kim ),우대곤 ( Dae Gon Woo ),박지형 ( Ji Hyung Park ),전옥희 ( Ok Hee Jeon ),이승학 ( Seung Hak Lee ),김지현 ( Chi Hyun Kim ),윤대성 ( Dae Sung Yoon ),김한성 ( Han Sung Kim ) 한국조직공학과 재생의학회 2010 조직공학과 재생의학 Vol.7 No.4

The present study was designed to evaluate the correlation between osteoporosis and osteoarthritis, based on micro-computed tomography (Micro-CT) and atomic force microscopy (AFM). To induce osteoporosis, virgin Sprague-Dawley rats (6 weeks old) were ovariectomized (OVX). All rats were randomly divided in two groups (normal group: 9, OVX group: 6). Knee joint on each rat was scanned by Micro-CT with 18-μm resolution at 0, 4 and 8 weeks. Morphological characteristics were calculated by Micro-CT image analyzer. Knee joint chondrocytes were isolated and immobilized to investigate morphological and mechanical characteristics on AFM measurements. In the OVX group, morphological characteristics significantly changed at all the femur over time(p<0.05). Comparing OVX group to normal group at 8 weeks, morphological characteristics and stiffness of chondrocytes measured by AFM significantly increased in normal group more than OVX group(p<0.05). The results showed that osteoporosis can cause osteoarthritis. The finding of the present study indicated that AFM can analyze the origin of osteoarthritis. In addition, this study is valuable attempt to find the correlation between osteoporosis and osteoarthritis.

Analysis of stress distribution of tooth restored with metal-ceramic crown covering abfraction lesion according to its finish line location under occlusal load

김지환,윤철욱,김태현,김한성,우대곤,이근우,심준성,Kim, Jee-Hwan,Yoon, Chol-Wook,Kim, Taehyeon,Kim, Han-Sung,Woo, Dae-Gon,Lee, Keun-Woo,Shim, June-Sung The Korean Academy of Prosthodonitics 2014 대한치과보철학회지 Vol.52 No.4

목적: 다양한 원인으로 발생된 Abfraction 병소가 있는 치아를 금속도재관으로 수복 할 경우, 변연의 위치에 따라 예후가 다양해질 수 있다. 수복물의 장기적 성공을 검증하기 위해서는 응력분포의 분석이 필요하지만 금속도재관이 abfraction 병소의 적응증인 경우 금속도재관이 응력 분포에 미치는 영향을 밝히는 연구는 아직 없다. 본 연구의 목적은 abfraction 병소가 있는 치아를 수복하는 금속도재관이 바람직한 응력 분포를 나타낼 수 있는 조건을 알아 보고자 함이다. 재료 및 방법: 치아, 주위 조직과 금속 도재관의 외형을 반영한 2차원 유한 요소모델을 제작하고 144 N의 편심 교합력 하에서의 응력분포를 유한요소 분석법으로 분석하였다. 금속 도재관의 변연 위치를 쐐기모양의 결손부의 하연에(Group 0), 그리고 결손부의 하연보다 1 mm 하방(Group 1)과 2mm 하방(Group2)에 위치시켰다. 결과: Group 0에서 von Mises stress는 금속 도재관의 변연과 결손부의 첨부에 집중 되었고 협측 변연의 응력은 설측 부위로 분포되었다. Group 1과 Group 2에서의 응력분포양상은 비슷하게 나타났다. 응력은 결손부의 첨부에 집중되지만 협측과 설측의 응력띠는 서로 분리된 양상으로 나타났다. 결론: 금속도재관의 변연을 Abfraction 병소의 하연에 설정할 경우, 금속도재관은 Abfraction 병소의 첨부에 응력을 집중시킨다. Purpose: When the full veneer crown was treated in the tooth with abfraction lesion due to various causes, the prognosis of it may be compromised according to the location of the finish line, but there is few study about the location of its buccal finish line. The purpose of this study was to investigate the effect of location of the finish line of the full veneer crown on stress distribution of the tooth with abfraction lesion. Materials and methods: The two dimensional finite element model was developed to express tooth, surrounding tissue and full veneer crown. The stress distribution under eccentric 144 N occlusal load was analyzed using finite element analysis. The location of finish line was set just at the lower border of the lesion (Group 0), 1 mm (Group 1) and 2 mm (Group 2) below the lower border of the lesion. Results: In the Group 0, von Mises stress was concentrated at the finish line and the apex of the lesion. Also, the stress at the bucal finish line propagated to the lingual side. In the Group 1 and Group 2, stress distribution was similar each other. Stress was concentrated at the apex of lesion, but the stress at the buccal finish line did not propagate to the lingual side. That implied decrease of the possibility of horizontal crown fracture. Conclusion: Full veneer crown alleviated the stress concentrated at the apex of the abfraction lesion, when the finish line of full veneer crown was set below the lower border of abfraction lesion.

성장기 저칼슘 섭취가 척추 골다공증 발생과 척추사이원반 변성에 미치는 영향 평가

박지형(Ji-Hyung Park),우대곤(Dae-Gon Woo),김치훈(Chi-Hoon Kim),이법이(Beob-Yi Lee),김지현(Chi-Hyun Kim),김한성(Han-Sung Kim) 대한체질인류학회 2009 해부·생물인류학 (Anat Biol Anthropol) Vol.22 No.3

본 연구는 성장기 때 저칼슘 섭취가 최대뼈질량을 감소시키고 뼈엉성증의 요인이 된다고 가정하고 칼슘제거사료를 공급하여 실험을 구성하였다. 변성된 척추사이원반은 해면뼈에 압력분포를 줄여주고 겉질뼈와 척추뒤돌기(가시돌기)의 압력분포를 증가시키며 해면뼈 면적을 줄여주어 골다공증을 유발할 수 있다는 다수의 연구가 발표되었지만, 골다공증이 유발된 척추가 척추사이원반 변성에 영향을 준다는 연구는 적고 골다공증이 유발된 척추에 인접한 정상 척추사이원반은 변성될 가능성이 있다는 가정을 확인하고자 하였다. 골다공증이 유발된 척추를 확인하기 위하여 살아있는 암컷 흰쥐의 허리뼈 전체(L1~L6)를 생체 내 미세단층촬영 시스템으로 촬영하고 유한요소 모델생성 및 가상 압축실험을 통하여 허리뼈의 형태학적 및 기계학적인 특성을 평가하였다. 골다공증으로 인한 척추의 골량감소와 미세구조의 변형이 척추사이원반에 어떤 영향을 미치는지를 확인하기 위해 조직학적 방법으로 관찰하였다. 통계처리는 일변량 ANOVA검정, Tukey’B검정, 대응표본 T검정을 수행하였다(p<0.05). 정상군의 해면뼈는 전체적으로 골량이 증가하였으나 칼슘제거군의 해면뼈는 골량이 감소하였다. 0주, 4주, 8주의 칼슘제거군에서 L3, L4, L5의 구조적 요소가 L1, L2, L6보다 모두 낮게 평가되었고, L3, L4, L5에서 해면뼈의 강도가 다른 부분에 비해 상대적으로 약한 구조임을 관찰할 수 있었다. 0주에서는 건강한 척추사이원반이 관찰되었다. 4주와 8주에서는 높이가 상대적으로 줄어들고 형태가 변하여 함몰된 모습을 관찰할 수 있다. 본 연구에서는 성장기에 칼슘을 섭취하지 못하면 뼈손실이 크게 발생됨을 확인할 수 있었다. 기존연구에서 더 나아가 첫째 허리뼈에서 여섯째 허리뼈까지(L1~L6) 골다공화에 따른 해면뼈의 구조적 및 기계적 특성 변화와 집중 하중을 받는 척추사이원반을 관찰하여 상호 연관성을 검토하였다. 골다공증은 뼈대계통 전체적으로 발생하나 허리뼈의 중심 부위인 L3, L4, L5가 외곽 부위인 L1, L2, L6에 비해서 약 1.8배 정도(중심부위: 122±101, 외곽부위: 224±118) 기계적 강도가 더 약하므로 L3, L4, L5의 해면뼈에서 골다공증이 가장 먼저 유발됨을 관찰하였고, 해면뼈의 뼈손실과 미세구조 변화에 따른 척추사이원반의 변성이 발생됨을 확인하였다. The aim of the present study is to analyze the generation of osteoporotic vertebral bone induced by malnutrition during growth period and analyze its effects for disc degeneration, based on biomechanical and histomorphometrical study. Mechanical and histomorphological characteristics of lumbar vertebral bones and discs of rats with calcium free diet (CFD) were detected and tracked by using high resolution in-vivo micro-computed tomography (in-vivo micro-CT), finite element (FE) and histological analysis. Twenty female Sprague-Dawley rats (6 weeks old, approximate weight 170g) were randomly divided into two groups (CFD group: 10, NOR group: 10). The CFD group was maintained on a refined calcium-controlled semisynthetic diet without added calcium, to induce osteoporosis. All lumbars (L1~L6) were scanned by using in vivo micro-CT with 35 μm resolution at 0, 4, 8 weeks to track the effects of CFD on the generation of osteoporosis. The results of morphological characteristics showed that BV/TV, Tb.Th, Tb.N in CFD group were significantly decreased over time (p<0.05), while those in NOR group were statistically increased over time (p<0.05) in the most lumbars (L1~L6). We also investigated the contrary tendency in Tb.Sp and SMI, compared to the above results in each group. In the simulated compression test using FE models, the structural effective modulus of CFD group significantly decreased (p<0.05), whereas that of NOR group was statistically increased, depending on the measuring time (p<0.05). The present study observed remarkable histological changes of nucleus pulposus and annulus fibrous by water loss in CFD group, compared with NOR group. These findings indicated that calcium insufficiency was the main factor in the generation of osteoporosis and it induced lumbar vertebral disc degeneration. This study is a valuable experiment to firstly evaluate osteoporotic vertebral bone and disc degeneration induced by malnutrition during growth period from a biomechanical and histomorphometrical point of view.

호르몬 결핍이 척추체에 미치는 영향 평가 : 골의 구조학적 및 질적 요소 분석

김치훈(Chi Hoon Kim),우대곤(Dae Gon Woo),박지형(Ji Hyung Park),이법이(Beob Yi Lee),김지현(Chi Hyun Kim),김한성(Han Sung Kim) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.5

This study evaluated the structure and quality of osteoporotic vertebral bone. To induce osteoporosis, eight rats were ovariectomized (OVX). All rats were divided into two groups (Normal group: 4, OVX group: 4). Total lumbar vertebrae for each rat were scanned by in-vivo μCT at 0, 4 and 8 weeks. Morphological characteristics (BV/TV, Tb.Th, Tb.N, Tb.Sp and SMI) were calculated by in-vivo μCT image analyzer. Three dimensional finite element models were analyzed to investigate bone strength of OVX and Normal groups. Moreover, the elastic modulus was quantitatively analyzed to evaluate the quality changes of osteoporotic bone. In the OVX group, BV/TV, Tb.Th and Tb.N were significantly decreased at all the lumbar over time (p<0.05). We also investigated a contrary tendency in Tb.Sp and SMI, compared to the above results in each group. A degree of alteration of mechanical characteristics in OVX group was decreased over measuring time (p<0.05). Bone quality presented by distribution of elastic modulus was improved in the Normal group more than OVX group. The findings of the present study indicated that both bone structure and quality of whole lumbar could be tracked and detected by analyzing the morphological and biomechanical characteristics of bones, based on a nondestructive method.

전신진동이 난소절제술을 시행한 흰쥐 해면뼈에 미치는 영향

고창용(Chang-Yong Ko),이태우(Tae-Woo Lee),우대곤(Dae-Gon Woo),김효선(Hyo-Seon Kim),임도형(Dohyung Lim),김한성(Han-Sung Kim),이법이(Beob Yi Lee) 대한체질인류학회 2007 해부·생물인류학 (Anat Biol Anthropol) Vol.20 No.4

골다공증모델과 전신진동(whole body vibration)에 대한 많은 연구에 따르면, 전신진동이 뼈의 재흡수를 억제하거나 뼈의 생성에 도움을 준다고 보고되고 있다. 하지만 동일 개체에 대하여 전신진동의 골다공증 예방 및 치료 효과에 대해 추적한 연구는 거의 없는 실정이다. 이에 본 연구에서는 다양한 주파수의 전신진동을 난소적출술을 시행한 쥐에게 가한 후 시기별로 해면뼈의 형태학적 특성 변화에 대해 추적 관찰하여 전신진동의 골다공증 치료 효과에 대하여 연구하였다. 12마리의 암컷 SD (Sprague-Dawley) 흰쥐를 대조군(CON), 샴수술군(SHAM), 전신진동군(WBV 17, WBV 30, WBV 45)으로 나누었다. 골다공증을 유발하기 위하여 sham수술군을 제외한 모든 쥐에게 난소적출을 시행하였다. WBV군의 흰쥐에게 1㎜peak-peak의진폭과각각17 ㎐ (WBV 17), 30 ㎐ (WBV 30), 45 ㎐ (WBV 45)의주파수를갖는 전신진동을 1주일에 5일, 매일 30분씩 가하였다. 진동을 가하기 전과 가한지 8주 후에 쥐의 4번째 허리뼈를 Invivo Micro-CT를 이용하여 35 μm의 해상도로 촬영하였다. 이때 획득한 영상을 이용하여 구조적인 파라미터들을 구하고 해면뼈의 형태학적인 특징 변화에 대해 관찰하였다. 그 결과 WBV 45군의 뼈의 양적인 손실이 가장 적었으며 뼈잔기둥의 형태학적인 변화 역시 가장 적었고, WBV 17군은 대조군에 비하여 뼈잔기둥의 형태학적인 큰 변화는 없지만 뼈의 양적인 손실이 대조군에 비해서도 큰 편임을 알 수 있었다. 위의 결과로부터 적절한 진동은 뼈의 양적인 손실 및 구조적 변화를 방지할 수 있다는 것을 알 수 있었지만, 잘못된 전신진동은 뼈의 손실을 더 가속화시키는 것으로 사료된다. 그러므로 전신진동이 골다공증 치료의 새로운 방법으로 제시되어질 수 있다고 사료된다. Previous studies showed that whole body vibration could prevent bone resorption and stimulate new bone formation. The aim of this study is to detect and track effect of whole body vibration for osteoporotic bone of OVX rats. 12 Female rats were used and allocated into 5 group, CON, SHAM, WBV 17, WBV 30 and WBV 45. Rats except SHAM group were ovariectomised to induce osteoporosis. Rats in WBV groups were stimulated whole body vibration at magnitude of 1 ㎜peak-peak and frequency 17 ㎐, 30 ㎐ and 45 ㎐, repectively, for 8 weeks (20 min, 5 days/week). The 4th lumbar in rats were scanned at a resolution of 35 μm at baseline, before stimulation, and 8 weeks by In-vivo Micro-CT. To detect and track changes of morphological characteristics in lumbar trabecuar bone of rats, structural parameters were measured and calculated from acquiring images. In the results, changes of structural characteristics of WBV group were smaller than those of CON group. Loss of quantity of trabecular bone in WBV 45 was the least. In contrast, that in WBV 17 was the biggest. These results showed that reasonable whole body vibration beneficially affected osteoporotic bones. In addition to, whole body vibration was likely to be substituted partly for drug treatment.

전신진동이 골다공증이 유발된 쥐 해면골에 미치는 영향

고창용(Chang Yong Ko),이태우(Tae Woo Lee),우대곤(Dae Gon Woo),김효선(Hyo Seon Kim),김한성(Han Sung Kim),이법이(Beob Yi Lee),임도형(Dohyung Lim) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.5

Pharmacotherapy was mainly used to treat osteoporosis. However, some researches showed that pharmacotherapy could induce unexpected adverse effects. Some studies showed that whole body vibration affected beneficially osteoporosis. This paper studied the effect of whole body vibration for osteoporosis compared with the effect of pharmacotherapy. 10 female rats were used and allocated into 4 group, CON, SHAM, DRUG, and WHY. Rats except SHAM group were ovariectomised to induce osteoporosis. Rats in WHV group were stimulated in whole body vibration at magnitude of 1㎜<SUP>peak-peak</SUP> and frequency 45㎐, for 8 weeks (30 min/day, 5 days/week). Rat in DRGU group was orally administered the Actonel (0.58㎎/㎏), for 8 weeks (5days/week). The 4<SUP>th</SUP> lumbar in rats were scanned at a resolution of 35㎛ at baseline, before stimulation, and 8 weeks after stimulation by In-vivo micro computed tomography. For detecting and tracking changes of biomechanical characteristics (morphological and mechanical characteristics) in lumbar trabecuar bone of rats, structural parameters were measured and calculated from acquiring images and finite element analysis was performed. In the results, loss of quantity and change of structure of trabecular bone in WBV group were smaller than those in both CON and SHAM groups. In addition, mechanical strength in WBV group was stronger than that in both CON and SHAM groups. In contrast, biomechanical characteristics in WBV group were similar with those in DRUG group. These results showed that reasonable whole body vibration was likely to treat osteoporosis and be substituted partly for drug treatment.