• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.932-938
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• 2001

This study is concerned with the shape optimization of stem for the artificial hip prosthesis with unbonded cement mantle. The artificial hip prosthesis with unbonded cement mantle allows a stem to slip on cement mantle because of polished stem surface. Unbonded cement mantle type has several advantages compared with bonded cement mantle type, for example, small micro motion, preventing stress shielding and so on. In this study, 2-dimensional axisymmetric model was developed with considering characteristics of unbonded cement mantle. Moreover, optimal shape of stem was obtained by using feasible direction method. The objective of this optimization is maximizing supported vertical loading. The slip motion and stresses of stem, cement mantle and bone is used for constraints. The optimal shape which obtained by this study has slope of 0.15 in proximal part and maintains the width about 5mm in distal part In addition, simplified 3-dimensional analysis which applying optimal shape is carried out. The result of 3-dimensional analysis showed that optimal shape has some advantages for cement mantle stress. However, more realistic 3-dimensional analysis which including bending effect, complex geometries etc. is needed in further research.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.1009-1010
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• 2009

• 센서학회지
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• 제20권4호
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• pp.254-259
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• 2011

In this paper, a current stimulator circuit with adaptive supply regulator for retinal prosthesis is proposed. In current stimulation systems, the stimulating circuits with wide voltage swing range are needed due to the high impedance of the retina cell and microelectrodes. Thus, previous researches adopt the high voltage architecture to obtain the enough operating range. The high voltage architecture, however, could increase the power consumption and can damage the retina cells. The proposed circuit provides the adaptively regulated supply voltage by measuring the difference between desired stimulation current and the actual stimulation current. The proposed circuit can achieve the extended range of the allowable cell impedance, improved accuracy of the stimulation current, and higher biosafety.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.407-408
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• 2008

• 대한의용생체공학회:의공학회지
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• 제26권5호
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• pp.257-264
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• 2005

This paper proposes an ionic polymer metal composite (IPMC) based artificial muscle to be applicable to the Myoelectric hand prosthesis. The IPMC consists of a thin polymer membrane with metal electrodes plated chemically on both faces, and it is widely applying to the artificial muscle because it is driven by relatively low input voltage. The control commands for the IPMC-based artificial muscle is given by electromyographic (EMG) signals obtained from human forearm. By an intended contraction of the human flexor carpi ulnaris and extensor carpi ulnaris muscles, we investigated the actuation behavior of the IPMC-based artificial muscle. To obtain higher actuation force of the IPMC, the single layered as thick as $800[{\mu}m]$ or multi-layered IPMC of which each layer can be as thick as $178[{\mu}m]$ are prepared. As a result, the bending force was up to the maximum 12[gf] from 1[gf] by actuating the single layered IPMC with $178[{\mu}m]$, but the bending displacement was reduced to 6[mm] from 30[mm]. The experimental results using an implemented IPMC control system show a possibility and a usability of the bio-mimetic artificial muscle.

• Composites Research
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• 제12권5호
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• pp.98-109
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• 1999

복합재료 보철물이 삽입된 인공 고관절의 장기적 거동의 해석을 위한 비선형 유한요소법이 개발되었으며 아울러 두꺼운 적층 복합채 보철물의 설계를 위한 3차원 육면체 요소가 이용되었다. 사용된 요소는 요소내의 다양한 물성치를 포함하여 요소의 절단면을 고려할 수 있는 ply-drop-off요소이다. 개발된 비선형 유한요소해석 프로그램은 단층하중하의 보 문제를 통해 엄밀해와의 비교를 통해 검증하였다. 개발된 프로그램을 이용하여 보철물의 재료와 복합재료 보철물의 적층각도에 따른 밀도 변화 및 강도비를 계산하여 인공 고관절의 역학적 거동을 해석하였으며 동시에 보철물의 설계 성능을 평가하였다. 계산된 수치해석 결과를 통해 인공 고관절 보철물의 설계 성능의 평가가 가능하며 보철물 설계에 따른 시간 및 비용을 줄일 수 있다.

• 대한기계학회논문집A
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• 제24권2호
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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.

• 대한치과기공학회지
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• 제41권2호
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• pp.93-100
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• 2019

Purpose: This study is making a dog dental prosthesis using digital dental technology. The mechanical strength of the prosthetic material was observed in terms of compressive strength and fracture pattern. Methods: The experiment was performed using dog mandibular molars. The teeth were scanned and modeled. The specimens were made of zirconia, PMMA and Ni-Cr. The specimens were subjected to a vertical compression test with an artificial cancellous bone in UTM tester. Vertical compressive strength and fracture behavior of specimen were observed. Results: The result of observing the compressive load between specimen and artificial bone were $184.8{\pm}5.7N$ in the zirconia specimen, $185.6{\pm}8.9N$ in the PMMA specimen, and $184.4{\pm}4.0N$ in the Ni-Cr alloy specimen. Compression marks of artificial bones were observed. The fracture strength of specimen was observed. The fracture strength of the zirconia specimen was an average of 1,381.4N. The fracture strength of the PMMA specimen was an average of 572.2N. Conclusion: The crown made of three kinds(zirconia, PMMA, Ni-Cr alloy) of materials has the strength to chew about the artificial bone. zirconia and PMMA have vertical compressive strength applicable to medium dog dental prosthetic materials.

• 대한기관식도과학회지
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• 제7권2호
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• pp.128-139
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• 2001

The purpose of this study was to review the literatures of experimental tracheal reconstruction. Although there have been significant advancements in the surgical treatment of the long circumferential tracheal injuries, there still has been a difficult problem with high morbidity and mortality. The method for tracheal reconstruction after circumferential resection is preferred end-to-end anastomosis for defects up to 6 cm in length, but larger tracheal defects require the use of tracheal allograft, various artificial prosthesis or autogenous organs. The tracheal allotransplantation has been widely used as there was significantly improved the method of surgical technique, preservation and immunosuppression. But it has been limited by a number of factors such as few donor, limited use of immunosuppressant, delayed revascularization and re-epitheliazation. Experimental studies on the tracheal prosthesis have a long history and they tried to use silicone, polytetrafluoroethylene, polypropylene mesh, Dacron, Marlex mesh, external or internal stents. Other experimental studies were reported the use of autogenous tissues that were cartilage. jejunum, aorta, skin, muscle, periostium or esophagus. But a great variety of these protheses have been resulted unsatisfactory in a significant Proportion of cases. Alternatively, the tissue-engineering technique has showed a new approach to reconstruct trachea and much progress in tissue-engineering bas been made recently. In conclusion, although the tracheal allotransplantation and the use of prosthesis and allograft have been reported a lot of limitation to overcome, we could sooner expect good result of ideal tracheal prosthesis.

• 대한의용생체공학회:의공학회지
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• 제19권3호
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• pp.291-296
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• 1998

설계방법론을 적용하여 새로운 기계식 인공심장판막을 설계 하였다. 심장판막의 기능을 정의하고 기능구조 결과에 따라 체계적인 설계변이 탐색을 수행하였으며, 이에 의하여 다양한 가능성을 검토하였다. 심장판막에 요구되는 제반 요구조건들을 기준으로 하여 최적 모델을 결정하였다. 설계된 심장판막의 시제품을 제작하여 모의순환계를 이용한 거동특성측정 실험을 수행하였다. 설계된 신규모델은 유량과 파형특성 및 거동특성면에서 대체로 양호한 결과를 보였다.