• 소성∙가공
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• 제17권2호
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• pp.91-96
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• 2008

The governing parameters affecting the fatigue properties have been investigated experimentally in the high carbon steel wires with 0.94 wt.%C. In order to find the crucial factors, the advanced analysis techniques such as optical 3-D profiler, focused ion beam(FIB) and transmission electron microscope(TEM) were used. The two-type steel wires with different drawing strain were fabricated. The fatigue properties were measured by hunter rotating beam tester, specially designed for thin-sized steel wires. It was found that the fatigue properties of the steel wires with high drawing strain was higher than that with other wires because of low residual stress and high adhesion condition of brass coating layer.

• Smart Structures and Systems
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• 제1권2호
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• pp.121-140
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• 2005

This paper presents a systematic investigation of the effect of sensor location on the data quality and subsequently, on the effectiveness of machine health monitoring. Based on an analysis of the signal propagation process from the defect location to the sensor, numerical simulations using finite element modeling were conducted on a bearing test bed to determine the signal strength at several representative sensor locations. The results showed that placing sensors closely to the machine component being monitored is critical to achieving high signal-to-noise ratio, thus improving the data quality. Using millimeter-sized piezoceramic plates, the obtained results were evaluated experimentally. A comparison with a set of commercial vibration sensors verified the developed structural dynamics-based sensor placement strategy. It further demonstrated that the proposed shock wave-based sensing technique provided an effective alternative to vibration measurement, while requiring less space for sensor installation.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권3호
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• pp.94-102
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• 2014

Purpose: This study aims to validate the effect of autoclaved autogenous bone (AAB), incorporating Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2), on critical-sized, segmental radius defects in rabbits. Delivery systems using absorbable collagen sponge (ACS) and fibrin glue (FG) were also evaluated. Methods: Radius defects were made in 12 New Zealand white rabbits. After autoclaving, the resected bone was reinserted and fixed. The animals were classified into three groups: only AAB reinserted (group 1, control), and AAB and ErhBMP-2 inserted using an ACS (group 2) or FG (group 3) as a carrier. Animals were sacrificed six or 12 weeks after surgery. Specimens were evaluated using radiology and histology. Results: Micro-computed tomography images showed the best bony union in group 2 at six and 12 weeks after operation. Quantitative analysis showed all indices except trabecular thickness were the highest in group 2 and the lowest in group 1 at twelve weeks. Histologic results showed the greatest bony union between AAB and radial bone at twelve weeks, indicating the highest degree of engraftment. Conclusion: ErhBMP-2 increases bony healing when applied on AAB graft sites. In addition, the ACS was reconfirmed as a useful delivery system for ErhBMP-2.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권2호
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• pp.220-229
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• 2008

Purpose: The present study was aimed to examine the effect of acellular dermal matrix ($AlloDerm^{(R)}$) grafted to the experimental tissue defect on tissue regeneration. Materials and Methods: Male albino rabbits were used. Soft tissue defects were prepared in the external abdominal oblique muscle. The animals were then divided into 3 groups by the graft material used: no graft, autogenous dermis graft, and $AlloDerm^{(R)}$ graft. The healing sites were histologically examined at weeks 4 and 8 after the graft. In another series, critical sized defects with 8-mm diameter were prepared in the right and left iliac bones. The animals were then divided into 5 groups: no graft, grafted with autogenous iliac bone, $AlloDerm^{(R)}$ graft, $AlloDerm^{(R)}$ graft impregnated with rhBMP-2, and $AlloDerm^{(R)}$ graft with rhTGF-${\beta}1$. The healing sites of bone defect were investigated with radiologic densitometry and histological evaluation at weeks 4 and 8 after the graft. Results: In the soft tissue defect, normal healing was seen in the group of no graft. Inflammatory cells and foreign body reactions were observed in the group of autogenous dermis graft, and the migration of fibroblasts and the formation of vessels into the collagen fibers were observed in the group of $AlloDerm^{(R)}$ graft. In the bone defect, the site of bone defect was healed by fibrous tissues in the group of no graft. The marked radiopacity and good regeneration were seen in the group of autogenous bone graft. There remained the traces of $AlloDerm^{(R)}$ with no satisfactory results in the group of $AlloDerm^{(R)}$ graft. In the groups of the $AlloDerm^{(R)}$ graft with rhBMP-2 or rhTGF-${\beta}1$, there were numerous osteoblasts in the boundary of the adjacent bone which was closely approximated to the $AlloDerm^{(R)}$ with regeneration features. However, the fibrous capsule also remained as in the group of $AlloDerm^{(R)}$ graft, which separated the $AlloDerm^{(R)}$ and the adjacent bone. Conclusions: These results suggest that $AlloDerm^{(R)}$ can be useful to substitute the autogenous dermis in the soft tissue defect. However, it may not be useful as a bone graft material or a carrier, since the bone defect was not completely healed by the bony tissue, regardless of the presence of osteogenic factors like rhBMP-2 or rhTGF-${\beta}1$.

• Journal of Periodontal and Implant Science
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• 제39권3호
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• pp.349-358
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• 2009

Purpose: This study was aimed to evaluate the effect of the Freeze Dried Bone Allograft and Demineralized Bone Matrix on osseous regeneration in the rat calvarial defects. Methods: Eight mm critical-sized calvarial defects were created in the 80 male Sprague-Dawley rats. The animals were divided into 4 groups of 20 animals each. The defects were treated with Freeze Dried Bone Allograft($SureOss^{TM}$), Demineralized Bone Matrix($ExFuse^{TM}$ Gel, $ExFuse^{TM}$ Putty), or were left untreated for sham-surgery control and were evaluated by histologic and histomorphometric parameters following a 2 and 8 week healing intervals. Statistical analysis was done between each groups and time intervals with ANOVA and paired t-test. Results: Defect closure, New bone area, Augmented area in the $SureOss^{TM}$, $ExFuse^{TM}$ Gel, $ExFuse^{TM}$ Putty groups were significantly greater than in the sham-surgery control group at each healing interval(P < 0.05). In the New bone area and Defect closure, there were no significant difference between experimental groups. Augmented area in the $ExFuse^{TM}$ Gel, $ExFuse^{TM}$ Putty groups were significantly greater than $SureOss^{TM}$ group at 2weeks(P < 0.05), however there was no significant difference at 8 weeks. Conclusions: All of $SureOss^{TM}$, $ExFuse^{TM}$ Gel, $ExFuse^{TM}$ Putty groups showed significant new bone formation and augmentation in the calvarial defect model.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제38권
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• pp.14.1-14.6
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• 2016

Background: In guided bone regeneration (GBR) technique, many materials have been used for improving biological effectiveness by adding on membranes. The new membrane which was constructed with chitin-fibroin-hydroxyapatite (CNF/HAP) was compared with a collagen membrane (Bio-$Gide^{(R)}$) by means of micro-computed tomography. Methods: Fifty-four rats were used in this study. A critical-sized (8 mm) bony defect was created in the calvaria with a trephine bur. The CNF/HAP membrane was prepared by thermally induced phase separation. In the experimental group (n = 18), the CNF/HAP membrane was used to cover the bony defect, and in the control group (n = 18), a resorbable collagen membrane (Bio-$Gide^{(R)}$) was used. In the negative control group (n = 18), no membrane was used. In each group, six animals were euthanized at 2, 4, and 8 weeks after surgery. The specimens were analyzed using micro-CT. Results: Bone volume (BV) and bone mineral density (BMD) of the new bone showed significant difference between the negative control group and membrane groups (P < 0.05). However, between two membranes, the difference was not significant. Conclusions: The CNF/HAP membrane has significant effect on the new bone formation and has the potential to be applied for guided bone regeneration.

• Archives of Plastic Surgery
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• 제32권3호
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• pp.335-342
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• 2005

This study was undertaken to investigate possibility of the allogenic type I collagen inducing osteoinduction or osteoconduction at critical sized bone defect in the rabbit. Twenty Newzealand white rabbit, weighted from 2.8 kg to 3.5 kg, were used in this study. The skull was exposed and two bony defects were created with diameter of 10 mm. Group I(n=10), the bony defects was grafted from the other side bone. Group II(n=10), the bony defects was grafted by the allogenic type I collagen with bone morphogenic protein(BMP). Group III(n=10), the bony defects was grafted by the allogenic type I collagen only. Group IV(n=10), the bony defects was lefted with no grafts. The grafted bones and allogenic type I collagen were investigated with radiologic densitometry, histologic analysis and immunohistochemistry after 12 weeks. No major difference was observed in the gross finding between Group I, II, III, but dura mater was exposed in bony defect,the Group IV. The radiologic study demonstrated more bony opacity in the Group I, but the other groups did not demonstrate a significant difference. In the histologic study, grafted bone edge was completely consolidated with original bone in group I and new bone ingrew into the grafted allogenic type I collagen(group II, III),but there is no bone regeneration from the original bony edge in the group IV. The percent of the new bone formation by cross-sectional area was considered statistically significant at a p value of less than 0.05(p<0.05). In the immunohistochemistry study about BMP antibodies, the group IV demonstrated osteogenic activity in front of advancing original bone edge, in which the osteoblast stained strongly for BMP antibodies, but other group does not demonstrated any osteoblastic expression. There was no immunologic rejection. In conclusion, this results do not demonstrate that the allogenic type I collagen is useful for bone substitute, but the characters of the collagen, such as pliability, easy-handling, sponge-like structure, are useful in interpositional bone graft substitutes. The further evaluation of long term results about the resorption, immunologic tissue reaction, response of applied tissue growth factor to the allogenic collagen is needed.

• 한국임상수의학회지
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• 제27권4호
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• pp.325-329
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• 2010

본 연구에서는 hydroxyapatite/poly $\varepsilon$-caprolactone composite (HA/PCL) 지지체와 matrigel을 랫드의 두개골 결손부 모델에 함께 이식 시의 골형성 정도를 평가하였다. 두개골결손부는 Sprague Dawley rat (n = 18)에서 수술적으로 형성하였으며 실험군은 Matrigel과 함께 HA/PCL 지지체를 이식한 군(M-HA/PCL group, n = 6)과 HA/PCL 지지체단독이식군(HA/PCL group, n = 6)으로 나누었고 대조군(CD group, n = 6)에는 아무 것도 이식하지 않았다. 수술 4주 후, 골형성은 방사선촬영, micro CT 및 조직검사를 통해 평가되었다. 방사선상에서 CD군의 골형성은 관찰되지 않았으나 HA/PCL과 M-HA/PCL군에서는 관찰되었고 골과 유사한 방사선비투과성이 M-HA/PCL군에서 더 많이 관찰되었다. Micro CT 평가에서 골부피는 HA/PCL군보다 M-HA/PCL군에서 더 높았으나 두 군 사이의 유의적 차이는 관찰할 수 없었다. 그러나 골밀도에서는 HA/PCL군보다 M-HA/PCL군이 더 유의적으로 높음을 확인할 수 있었다(p < 0.05). 조직학적 검사에서는 CD군에서 새로운 골은 원래 존재하던 골로부터만 형성되었으며 두개골결손부 내의 골형성은 보이지 않았다. HA/PCL군에서 새로운 골형성은 원래 존재하던 골로부터만 유래되었으나 M-HA/PCL군은 가장 많은 골형성을 보여주었으며 새로운 골이 원래 존재하던 골과 HA/PCL지지체 주변에서도 관찰되었다. 이러한 결과로 미루어볼 때 HA/PCL 지지체와 matrigel을 함께 사용하는 것이 골의 임계결손부에서 골형성을 증대시키는 효과적인 방법이 될 수 있을 것으로 생각된다.

• 한국방사선학회논문지
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• 제5권1호
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• pp.11-18
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• 2011

다능성 세포를 포함하는 골막은 골모세포와 연골세포로 분화될 수 있다. 그리고 배양된 골막유래세포는 골형성 능력을 가지고 있다. 이 연구의 목적은 골막유래 세포들과 골이식재 간의 상호작용을 평가하는 것이다. Sprague-Dawley 랫드의 두개골 골막에서 세포를 분리한 다음, 배양된 골막유래세포를 beta-tricalcium phosphate (${\beta}$-TCP)와 함께 임계결손부 크기의 두개결손부에 이식하였다. 모든 랫드는 골이식 수술 후 8주째에 희생되었으며, 골이식부의 골형성 능력은 일반방사선, micro CT 및 조직검사를 통해 평가되었다. ${\beta}$-TCP와 함께 이식된 골막유래세포는 골결손부에서 더욱 증가된 석회화작용을 나타내었으며, 골결손부 안쪽 및 가장자리에 골밀도 증가와 신생골이 형성되었다. 특히 골막유래세포는 ${\beta}$-TCP만 단독으로 이식하였을때보다 함께 이식 시 효과적으로 신생골을 형성하였다. 이러한 결과는 배양된 골막유래세포가 골결손부에서 골형성을 증진시킬 수 있는 가능성을 보였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제43권6호
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• pp.373-387
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• 2017

Objectives: The purpose of this study was to introduce our three experiments on bone morphogenetic protein (BMP) and its carriers performed using the critical sized segmental defect (CSD) model in rat fibula and to investigate development of animal models and carriers for more effective bone regeneration. Materials and Methods: For the experiments, 14, 16, and 24 rats with CSDs on both fibulae were used in Experiments 1, 2, and 3, respectively. BMP-2 with absorbable collagen sponge (ACS) (Experiments 1 and 2), autoclaved autogenous bone (AAB) and fibrin glue (FG) (Experiment 3), and xenogenic bone (Experiment 2) were used in the experimental groups. Radiographic and histomorphological evaluations were performed during the follow-up period of each experiment. Results: Significant new bone formation was commonly observed in all experimental groups using BMP-2 compared to control and xenograft (porcine bone) groups. Although there was some difference based on BMP carrier, regenerated bone volume was typically reduced by remodeling after initially forming excessive bone. Conclusion: BMP-2 demonstrates excellent ability for bone regeneration because of its osteoinductivity, but efficacy can be significantly different depending on its delivery system. ACS and FG showed relatively good bone regeneration capacity, satisfying the essential conditions of localization and release-control when used as BMP carriers. AAB could not provide release-control as a BMP carrier, but its space-maintenance role was remarkable. Carriers and scaffolds that can provide sufficient support to the BMP/carrier complex are necessary for large bone defects, and AAB is thought to be able to act as an effective scaffold. The CSD model of rat fibula is simple and useful for initial estimate of bone regeneration by agents including BMPs.