• PNF and Movement
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• v.10 no.1
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• pp.61-70
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• 2012

Purpose : The purpose of this study was to investigate thigh muscle-bone CSA and leg strength during low-intensity exercise program with leg blood flow restriction by external compression to reduce muscle outflow. Methods : Eighteen health students gave informed written consent to participate in this investigation. An occlusion cuff was attached to the proximal end of the leg so that blood flow was reduced during the training. The training was conducted one times a day, three times a week, for 8 weeks using one sets of 30 minutes. The training program performed to squat with standing, lunge with standing and heel raise with one leg standing. Measurements of thigh muscle-bone CSA(cross-sectional area) and leg strength were evaluated pre and post-training. Statistical evaluation of these data was accomplished utilizing a paired t-test by SPSS 12.0 program for windows. Significance level was set at p <.05. Results : All data are reported as means and standard deviations(SD) for all variables. The result of the study is followed; After the training, muscle-bone CSA, gluteus maximus m, quadriceps m, hamstring m of both legs were significantly improved but not calf muscle(p<.05). There was no significant difference of change quantity between muscle-bone CSA and leg strength in Lt. and Rt. side. But the variation in leg muscle strength of Rt. leg(dominant) was much more increased than Lt. leg(non-dominant) after 8 weeks training. Conclusion : Low-intensity training with leg blood flow restriction offers a potentially useful method for improving leg muscle strength.

• Korean Journal of Materials Research
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• v.16 no.4
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• pp.272-275
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• 2006

In order to evaluate the possibility of Polymethyl methacrylate (PMMA) as a binder on hydroxyapatite (HAp) which has good biocompatibility, the properties of HAp compacts with PMMA were examined. When adding 50 wt% of PMMA on HAp and pressed, the compression strength and the hardness of the compacting body were 168MPa and 55 Hv, respectively, and the strength of compacts was higher than that of cortical bone and the hardness was similar to the value of molar. We demonstrated that HAp ceramics can be obtained without additional heat treatment and machining of the ceramic was feasible. Therefore, the HAp compacts have potential to apply to implant or artificial bone after the clinical trials guarantees biocompatibility of it.

• Korean Journal of Materials Research
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• v.20 no.6
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• pp.312-318
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• 2010

Multilayer Poly methyl methacrylate (PMMA)/ Poly vinyl alcohol (PVA) bone plates were fabricated using electrospinning and in vitro investigations were carried out for pre-clinical biocompatibility studies. The initial cellular cytotoxicity of the methacrylate (PMMA)/ Poly vinyl alcohol (PVA) bone plates was measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay using fibroblast-like L-929 cells. Cellular adhesion and differentiation studies were carried out using osteoblast-like MG-63 cells. As simulated body fluid (SBF) contains the same ionic concentration of body fluid and any bioactive material tends to deposit bone-like apatite on the samples surfaces into the SBF, in vitro bioactivity of the multilayer bone plates were investigated using SBF. We also studied the internal organization and tensile strength of the multilayer PMMA/PVA bone plates using micro-computed topography (${\mu}$-CT) and universal testing instrument (UTI, Korea) respectively. The cellular cytotoxicity study with MTT confirmed that the cellular viability was 78 to 90% which indicates good cyto-compatibility. Scanning electron microscopic findings revealed a good attachment and adhesion phenomenon of MG-63 cells onto the surfaces of the samples. Cellular differentiation studies also showed that osteogenic differentiation was switched on in a timely manner and affirmed along with that of the control group. Bone-like apatite formation on the surfaces was confirmed within 14 days of SBF incubation. Initial organizations of the multilayer PMMA/PVA bone plates were characterized as dense and uniform. The tensile strength of the post-pressing electronspun mat was higher than that of the pre-electronspun mat. These results suggest that a multilayer PMMA/PVA bone plate system is biocompatible, bioactive and a very good alternative bone plate system.

• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.1022-1031
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• 2001

The elastic modulus and fatigue properties of canine and human trabecular bone tissues (single trabecular) were experimentally determined on a microstructural level using four-point bending cyclic test, and they were compared based on microstructural characteristics and mineral density. The results showed that canine trabecular bone tissue had significantly lower modulus and lower fatigue strength than human tissue. The observed microstructural differences between the two tissues may be more responsible for the differences, although the lower mineral density in canine tissue might also have contributed to the lower modulus and fatigue strength.

• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.57-60
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• 1995

To develop an artificial bone substitute that is gradually degraded and replaced by the regenerated natural bone, the authors designed and produced a composite that is consisted of calcium phosphate and collagen. Human umbilical cord origin pepsin treated type I atelocollagen was used as the structural matrix, by which sintered or non-sintered carbonate apatite was encapsulated to form an inorganic-organic composite. With cross linking atelocollagen by UV ray irradiation, the resistance to both compressive and tensile strength was increased. Collagen degradation by the collagenase induced collagenolysis was also decreased.

• International Journal of Oral Biology
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• v.32 no.4
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• pp.143-151
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• 2007

This study was conducted to investigate the preventing effects of OPB (Rehmannia glutinosa Libosch and Eleutherococcus senticosus Max extracts) and combined OPB/Calcium therapy on bone loss in ovariectomized rats. Sixty Sprague Dawley rats of 12-week-old were divided into eight groups: OVX (ovariectomized), OPBL (OPB 50 mg/kg), OPBM (OPB100 mg/kg), OPBH (OPB 200 mg/kg), OPBL/CAL(OPBL+CAL), OPBM/CAL (OPBM+CAL), OPBH/CAL (OPBH+CAL) and CAL (Calcium citrate 88.33 mg/kg+1$\alpha$, 25-dihydroxy-vitamin $D_3$ 33.33 IU/kg). Bone mineral density (BMD), bone mineral content (BMC), bone strength indices and cortical thickness were analyzed by peripheral quantitative computerized tomography (pQCT). pQCT scanning showed that OVX induced a significant decrease in trabecular bone mineral density and bone mineral content in the proximal tibia $(-36.4\pm2.4%,\;-21.8\pm12.7%)$. These decreases were significantly prevented by the administration of OPBM and OPBM/CAL. Cortical BMD and BMC of tibia were slightly enhanced by OPB and OPB/CAL. However there was no significant difference between OVX and OPB, OPB/CAL treated group. Bone strength indices and cortical thickness were not significantly different. Our results suggest that OPB and combined OPB/Calcium therapy are effective in preventing the development of bone loss induced by ovariectomy in rats.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.518-521
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• 2005

We performed the mechanical test for obtaining properties of femoral head. Tested sample was male and 35 years old. We measured bone mineral density by dual X-ray absorption method(DEXA). Results of DEXA, he has normal condition of bone density. His BMD $1.159g/cm^2$ and T-Score is 1.6. Tested femurs were harvested by surgical method from donated cadaver. We made 9 specimens in femoral head, 8 specimens in neck used by diamond core drill. Then we performed compressive test in saline solution at $38^{\circ}C$. We obtained results that elastic modulus of femoral head was 0.439GPa, neck was 0.459GPa. Compressive strength of femoral head was 7.441 MPa, neck was 7.095MPa. There was no significant difference of mechanical properties between left and right femoral head & neck. Invested local properties of femoral head have more strength superior and anterior side, femoral neck has more strength in superior and inferior side but other side except for superior has more weakness along the lateral side.

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.57-67
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• 2002

The effect of $\beta$-TCP and PHA as additives on initial setting time, compressive strength and surface micro-structure after in vitro test of bone cement in TTCP and DCPA system was investigated. The median particle sizes of TTCP, $\beta$-TCP, DCPA and PHA for bone cement were about 3, 5, 0.9 and 4${\mu}{\textrm}{m}$, respectively. Initial setting time and compressive strength of bone cement with various composition was measured by Vicat test and Universal Testing Machine, and surface morphology and crystalline phases of bone cements were observed and analyzed by SEM and x-ray diffractometer. Initial setting time was not affected by composition but by powder/liquid ratio, and cement with PHA required double amount of solution for paste as much as one without PHA, especially. It was thought that $\beta$-TCP and PHA in bone cements was not related to setting reaction. Thus, the addition of $\beta$-TCP and PHA in bone cements decreased compressive strength and inhabited HAP from being produced on surface in vitro test. In conclusion, it was not expected that $\beta$-TCP and PHA in TTCP-DCPD bone cements enhanced the strength and bioacitivity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.146-149
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• 2002

It is reported that the mechanical properties of vertebral trabecular bone depend on the density and the mass of bones. Osteoporosis is a systemic skeletal disease caused by low bone mass and microstructure deterioration of trabecular bone. Silva and Gibson (1997) studied the treatment of age-related bone loss using drug therapy. Vertebroplasty is a minimally invasive surgery for the treatment of osteoporosis vertebrae. This procedure includes puncturing vertebrae and filling with Polymethylmethacrylate (PMMA). However, the relative effect of drug therapy and bone cement for osteoporosis treatment is not reported yet. In this study, several 2D models of human vertebral trabecular bone are analyzed by finite element method. The mechanical behaviors of the vertebral trabecular bone treated by the drug therapy and the bone cement are compared. This study shows that bone cement treatment is more effective strategy than drug therapy to prevent the degradation of bone strength.

• The Journal of the Acoustical Society of Korea
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• v.29 no.2E
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• pp.64-72
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• 2010

Osteoporosis is a skeletal disease characterized by two factors: reduced bone mass and microstructure disruption of bone tissue. These symptoms increase bone fragility and can contribute to eventual fracture. In recent years, quantitative ultrasound (QUS) technologies have played a growing role in the diagnosis of osteoporosis. Most of the commercial bone sonometers measure speed of sound and/or broadband ultrasound attenuation at peripheral skeletal sites. However, QUS parameters are purely empirical measures that have not yet been firmly linked to physical parameters, such as bone strength or porosity, and the underlying physics for their variations in cancellous bone is not well understood yet. This paper reviews the QUS technologies for the diagnosis of osteoporosis and also addresses several theoretical models, such as the Biot model, the scattering model, the stratified model, and the modified Biot-Attenborough model, for ultrasonic wave propagation in bone.