• Korean Journal of Veterinary Research
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• v.37 no.4
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• pp.863-873
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• 1997

Electrical stimulation and vitamin $AD_3E$ administration have been shown to enhance the repair of biological tissues such as bone, ligament and tendon, The objective of this study were (a) to investgate the therapeutic effects of different levels of electrical stimulation and vitamin $AD_3E$ administration on fracture healing in a rat model and (b) to identify the most effective voltage level. Ninety Sprague-dawley rats were divided into electrical stimulation group and vitamin $AD_3E$ administration group. Electricla stimulation group was divided into four groups on the basis of the level of current delivered. The experimental groups received current (which varied by group), while the controls, with identical electrodes, received no current. In vitamin $AD_3E$ administration group, experimental group was injected 2,500 IU of vitamin A, 1,250 IU of vitamine $D_3$, 1mg of vitamine E intramuscularly. And in control group 0.1ml of saline was injected intramuscularly. After time periods (7-day, 14-day, 21-day for stimulation all rats were tested with combination of biochemical, roentgenologic and histomorphological methods. The results obtained were as follows ; In electrical stimulation groups, serum calcium and inorganic phosphorus level of experimental and control groups showed non specific change within normal physiological ranges. In vitamin $AD_3E$ administration group, serum calcium level of experimental and control groups showed non specific changes within normal physiological ranges, while experimental group showed slightly higher serum inorganic phosphorus level. According to roentgenologic and histomorphological examination, 2V 25Hz electrical stimulation group and vitamine $AD_3E$ administration group showed statistically significant improvements in bone density and ossification reaction until day 14. The terapeutic effect of stimulation on fracture healing was similiar to that of vitamin $AD_3E$ administration. In this study stimulation of 2V 25Hz was the most effective level of electrical stimulation for the healing of fracture of rats.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.6
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• pp.520-530
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• 2006

Undifferentiated mesencymal stem cells(UMSCs) have been thought to be multipotent cells that can replicate as undifferentiated cells and that have the potential to differentiate into lineages of mesenchymal tissue including the bone, cartilage, fat, tendon, muscle, and marrow stroma. It can be used to sinus lifting, Guided bone regeneration, other bone graft in dental part. The purpose of this study is to evaluate the effect of mesencymal stem cells on sinus augmentation with autogenous bone, fibrin glue mixture in a rabbit model. 8 New Zealand white rabbits were divided randomly into 4 groups based on their time of sacrifice(1, 2, 4 and 8 weeks). First, undifferentiated mesenchymal stem cells were isolated from iliac crest marrow of rabbits and expanded in vitro. cell culture was performed in accordance with the technique described by Tsutsumi et al. In the present study, The animals were sacrificed at 1, 2, 4 and 8 weeks after transplantation, and the bone formation ability of each sides was evaluated clinically, radiologically, histologically and histomorphologically. According to the histological observations, Stem cell group showed integrated graft bone with host bone from sinus wall. At 2 and 4weeks, It showed active newly formed bone and neovascularization. At 8 weeks, lamella bone was observed in sinus graft material area. Radiologically, autobone with stem cell showed more radiopaque than autobone without stemcell. there were significant differences in bone volume between 2 and 4 weeks (p<0.05). In summary, the autobone with stem cells had well-formed, newly formed bone and neovasculization, compared with the autobone without stem cells (esp. 2 weeks and 4 weeks) The findings of this experimental study indicate that the use of a mixture of mesenchymal stem cell yielded good results in osteogenesis and bone volume comparable with that achieved by autogenous bone. Therefore, this application of this promising new sinus floor elevation method for implants with tissue engineering technology deserves further study.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.23-32
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• 2017

The joints between precast PSC slabs of the intermediate road slab in double deck tunnel are inevitably generated in the road traffic vehicle traveling direction. Therefore, it is important to make the behavior of parts on the joint in one piece. The imtermediate road slab system of double deck tunnel in great depth proposed in this study will be constructed with precast PSC slab in order to minimize the construction period. And the joint connection between the precast slab has been developed in two methods: the 'Transverse tendon reinforcement method' and 'High strength bolts connection method'. Also, the experiments were performed for the full scale model in order to evaluate the performance of the intermediate road deck slab with two type joints systems, the structural stability was verified through the F.E.M analsysis. The results of static loading test and F.E.M analysis investigated a very stable behavior of intermediate road deck slab in double deck tunnel applying the joint methods developed in this study, in the cracks and deflections to satisfy the design standards of Highway Roads Bridges (2011), it was determined that there is no problem even servicebility.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.5
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• pp.405-418
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• 2007

Mesenchymal stem cells(MSCs) have been though to be multipotent cells that can replicate that have the potential to differentiate into lineages of mesenchymal tissue including the bone, cartilage, fat, tendon, muscle, and marrow stroma. Especially, scaffolds to support cell-based tissue engineering are critical determinants of clinical efforts to regenerate and repair the body. Selection of a matrix carrier imvolves consideration of the matrix's role as a scaffold for physical support and host tissue integration as well as its ability to support of synergize the osteoinductive program of the implanted mesenchymal stem cell. The aim of this study is to evaluate the effect of autobone and Bio-$Oss^{(R)}$ to adherent mesenchymal stem cells as scaffolds on sinus augmentation with fibrin glue mixture in a rabbit model. 16 New Zealand White rabbits were divided randomly into 4 groups based on their time of sacrifice(1, 2, 4 and 8 weeks). First, mesenchymal stem cells were isolated from iliac crest marrow of rabbits and expanded in vitro. Cell culture was performed in accordance with the technique described by Tsutsumi et al. In the present study, the animals were sacrificed at 1, 2, 4 and 8 weeks after transplantation, and the bone formation ability of each sides was evaluated clinically, radiologically, histologically and histomorphologically. According to the histological observations, autobone scaffolds group showed integrated graft bone with host bone from sinus wall. At 2 and 4 weeks, it showed active newly formed bone and neovascularization. At 8 weeks, lamellae bone was observed in sinus graft material area. Radiologically, autobone with stem cell showed more radiopaque than Bio-$Oss^{(R)}$ scaffolds group. there were significant differences in bone volume between 4 and 8 weeks(p<0.05).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.535-542
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• 2015

A reactor containment acts as a final barrier to prevent leakage of radioactive material due to the possible reactor accidents into external environment. Because of the functional importance of the containment building, the SIT(Structural Integrity Test) for containments shall be performed to evaluate the structural acceptability and demonstrate the quality of construction. In this paper, numerical analyses are presented, which simulate the results obtained from the SIT for a prestressed concrete(PSC) structure. A sophisticate structural analysis model is developed to simulate the structural behavior during the SIT properly based on various preliminary analysis results considering contact condition among structural elements. From the comparison of the analysis and test results based on the acceptance criteria of ASME CC-6000, it can be concluded that the construction quality of the containment has been well maintained and the acceptable performance of new design features has been verified.

• Journal of Korean Orthopaedic Sports Medicine
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• v.2 no.1
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• pp.28-36
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• 2003

Purpose: To determine and to compare the effects of cyclic loading on the fixation strength of different femoral fixation methods in ACL reconstruction. Materials and Methods: Biomechanical test using an Instron(R) machine (Model No.5569. Mass, U.S.A) were carried out to compare the pull out strength of six different femoral fixation techniques after a cyclic loading in 72 Yorkshire pig knees. The graft-bone complex was cyclically loaded between 30N and 150N at 50 mm/min rate for 1000 cycles and maximal tensile testing was performed. A preload of 30N was applied to the graft along the axis of the tunnel 15 minutes. ANOVA and the Duncan multiple comparison test was used for the statistical analysis. Results: The mean maximum tensile strength of femoral fixation before and after the cyclic loading test were 1003.4$\pm$145N and 601.1$\pm$154N in hamstring-LA screw(R) group, 595.5$\pm$104N and 360.7$\pm$56N in hamstring-Bioscrew(R) group, 1431.7$\pm$135N and 710.7$\pm$114N in hamstring-Semifix(R) group, 603.6$\pm$54N and 459.1$\pm$46N in hamstring-Endobutton(R) fixation group, 1067.4$\pm$145 and 601.8$\pm$134N in the BPTB-Titanium interference screw group, and 987.1$\pm$168N and 588.7$\pm$124N in the BPTB-Bioscrew(R) group. And these data illustrated that cyclic loading reduces the maximum tensile strength by 40 $\%$, 39 $\%$, 50 $\%$, 24 $\%$, 44 $\%$, 40 $\%$ respectively. Conclusions: With the results of these experiments it should be emphasized that rehabilitation exercises after anterior cruciate ligament reconstruction should be executed with precaution as the repetitive flexion and extension of the knee would compromise the maximum tensile strength of the graft tendon.