• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.234-238
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• 1999

This study suggests the design of the functionally gradient composite, [0/90/0/core]$_s$ cross-ply laminate, to prevent stress concentration induced from the difference of rigidity between the bone and the artificial hip joint and to reinforce the wear property of the surface and the expectation of their mechanical properties. First, the four-point bending test is done about wet bones and dry bones to know the mechanical properties of the cortical bones. In result, the wet bone shows the viscoelastic behavior and the dry bone shows the elastic behavior. Moreover, we expect the properties of the proposed gradient composites as a function of carbon fiber volume fraction in each layer to apply Halpin-Tsai equation, CLPT(classical laminate plate theory), and Bernoulli beam theory etc. and decide the thickness ratio of each lamina in order to match Young's modulus of the anisotropic cortical bone with the proposed gradient composites.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.163-168
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• 2009

In this study, we would be developed the fuzzy controlled PGO that controlled the flexion and the extension of each PGO's hip joint using the bio-signal and FSR sensor. The PGO driving system is to couple the right and left sides of the orthosis by specially designed hip joints and pelvic section. This driving system consists of the orthosis, sensor, control system. An air supply system of muscle is composed of an air compressor, 2-way solenoid valve (MAC, USA), accumulator, pressure sensor. Role of this system provide air muscle with the compressed air at hip joint constantly. According to output signal of EMG sensor and foot sensor, air muscles and assists the flexion of hip joint during PGO gait. As a results, the maximum hip flexion angles of RGO's gait and PGO's gait were about $16^{\circ}\;and\;57^{\circ}$ respectively. The maximum angle of flexion/extention in hip joint of the patients during RGO's gait are smaller than normal gait, because of the step length of them shoes a little bit. But maximum angle of flexion/extention in hip joint of the patients during PGO's gait are larger than normal gait.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.329-337
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• 2000

An investigation has been performed to develop an analysis tool based on a nonlinear beam theory, which can be used to predict the long-term behavior of an artificial hip joint. The nonlinear behav ior of the femur arise from the coupled dependence of the bone density and the mechanical properties on each other. The beam theory together with its numerical algorithm is developed to take into account the nonlinear bone remodeling process of the femur that is long enough to be assumed as a beam. A piecewise linear curve for the bone remodeling rate is used in the bone remodeling theory and the surface area density of bone is modeled as the third order polynomial function of bone density. At each section of the beam, a constant curvature is assumed and the longitudinal strains are also assumed to vary linearly across the section. The Newton-Rhapson iteration method is used to solve the nonlinear equations for each cross section of the bone and a backward method is used to march along the time. The density and the remodeling signal ar, calculated along with time for the various time steps, and the developed beam theory has been verified by comparing with the results of finite element analysis of a remodeling bone with an artificial hip joint of titanium prosthesis subjected to uni-axial loads and pure bending moment. It is concluded that the developed beam theory can be used to predict the long-term behavior of the femur and thus to design the artificial hip prosthesis.

• Journal of Biomedical Engineering Research
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• v.22 no.6
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• pp.519-526
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• 2001

At present. about 0.3 million and more THRs (Total Hip Replacement) in a rear are being done worldwide. The increase in mechanical failure with the increase in THR, required more revisions. Revisions compensate mainly the wear of the artificial joint frictional surface and the loosening of the cup and stem. According to recent researches, loosening is mainly due to wear debris UHMWPE (Ultra High Molecular Weight Polyethylene) from frictional surfaces . To overcome the wear problems associated with artificial joint materials , new surface structures with regular Patterns were designed and fabricated The lubrication Properties were examined to evaluate the wear of the frictional surfaces. The surface structure manifested a Pattern of "dents" with a 0.2-1.0 mm of diameter and 0.6-2.0 mm of Pitch. From the friction test of the SUS316L vs UHMWPE using the frictional tester, we found that the lubrication Performance was improved due to of drastically reduced amount of abrasion. There were optimum sizes for the diameter and the pitch of the Pattern. The results demonstrated that the lubrication properties could be improved by Patterning of the frictional surfaces. The surface Patterning was effective in preventing wear of the frictional surfaces, and the life of an artificial joint could be extended with such Patterning.

• Journal of Biomedical Engineering Research
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• v.21 no.2
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• pp.201-212
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• 2000

본 논문에서는 인공고관절과 환자의 고관절 부위를 각각 3차원 영상화한 후에 이들의 정합도 (fitness)를 측정하여 수치적인 정보로 제공함으로써 환자의 체형에 적합한 인공고관절을 선택하고, 더 나아가 정확한 시술방향과 시술깊이를 제공할 수 있는 모의시술시스템을 제시하였다. 이를 위해 region growing 기법등을 이용하여 환자의 CT 영상을 3차원화하고, 또한 인공고관절을 projection 기법 등을 통해 3차원 영상화하였으며, 지금까지 인공고관절 정합도 측정에 사용했던 단순한 단면적 비교방식과는 달리 삽입의 균일성도 가늠할 수 있는 새로운 정합도 측정 방식을 고안하여 적용하였다. 다양한 실험과 분석을 통하여 새로 제안한 정합도 측정 방법의 정확성과 우수함을 확인할 수 있었으며, 본 논문에서 제시하는 모의 시술시스템은 향후 정형외과 분야에서 인공무릎과 같은 다른 영역에서의 시술 보조 시스템으로도 응용될 수 있을 뿐만 아니라, 인공관절의 국산화 및 주문제작 등에성도 많은 활용을 할 수 있을 것으로 기대된다.

• Proceedings of the KOSOMBE Conference
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• v.1990 no.11
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• pp.1-4
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• 1990

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.155-162
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• 1993

The human's biomechanical structure keeps an optimal state by adapting the original biomechanical structure according to a change in the physical environment. This phenomenon is believed to be the main cause of loosening of the total hip replacement which is used widely in these days. In this study the bone density change due to artificial hip joint, which is generally believed as bone-remodeling, was investigated by the finite element method. For this, 2-D FEM models with 4 nodal point elements were constructed for intact and implanted cases. The density was calculated by comparing the relative amounts of effective stress for these two cases. In this way, calculated new density values were used in the next step as input values and this procedure repeated until convergence was obtained. Severe density change was detected at the femoral cortex of the proximal-medial side as expected. Moreover, following surprising result was found from this analysis. Titanium alloy prosthesis showed less density change compared to stainless steel prosthesis at earlier stage, however, almost same amount of the density change was detected at final stage. It was also found that other design parameters could not significantly affect its density change.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.3-7
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• 2014

Purpose SPECT/CT scan to be performed attenuation correction on the basis of CT induce an overestimation of the site due to the beam hardening artifact by metal cover and reduce the images quality. Therefore, this study using a phantom that has been inserted artificial hip joint investigated that effect on the SPECT/CT image causing by metal artifact for varying the parameters of the Attenuation Map. Materials and Methods Siemens Symbia T16 SPECT/CT equipment was used. Artificial hip joint was inserted to SPECT/PET phantom, 17 mm sphere of Bright Streak area in CT image was filled with Tc-99m so that the radiation activity was 8 times compared to background. And then Hot and Background was measured in varying Wide Beam Coefficient on Attenuation Map and RBR (Region to Background Ratio) of Metal and Non-Metal was calculated and analyzed depending on the presence or absence of the hip joint. Results It tended to hot count of Non-Metal and Metal to increase as the value of the manual mode is increased, hot count ratio with the group of both manual mode 0.5 and 0.4 is the best match. Also, in automatic mode, the ratio of RBRNon-Metal and RBRMetal was 1.135, statistically significant difference was not observed in the manual mode 0.5 and 0.4. Conclusion In the automatic mode of Wide Beam Coefficient in attenuation correction map, it was found that it is over-correction by 13.52%, it was possible to minimize the over-correction by the artifact in 0.5 and 0.4 of manual mode. Further studies should be performed in order to apply to a patient with the help of this and it is considered possible to reduce the over-correction by the metal artifact of an artificial hip joint for Hip-Resurfacing Arthroplasty patients, and to improve the diagnostic performance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.33-39
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• 2016

This study investigated the dynamic instability of a ceramic-on-ceramic artificial hip joint system through complex eigenvalue analysis. We examined the mode-coupling mechanism through eigenvalue sensitivity analysis with the variation of system parameters. In addition, we constructed a finite element model including the negative slope of friction curve for investigating the negative-slope mechanism in the hip squeak problem. The numerical results show that the torsion-dominant mode becomes unstable due to the presence of the negative slope while the axial load is the important factor influencing the negative-slope type instability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1491-1492
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• 2011