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고철수,이만섭,최귀원,Koh, Chul-Su,Lee, Man-Sup,Choi, Kui-Won 대한치주과학회 1997 Journal of Periodontal & Implant Science Vol.27 No.1
Homogenization technique is employed to investigate the series of stress analyses of mandible for three different types of dental implants. This technique helps to make proper material model of bone and analyze such a non homogeneous structure at the level of individual microstructural unit. The stress analyses with homogenization technique show much higher stress level in the sponge bone, compared to those of conventional FEM. It also manifested that even a minor lateral force results in crucial stresses in the dental implant system and that the macroscale model should take the shape and size after real mandible to produce reasonable solution in the analyses of dental implant systems. The shapes of dental implants simulated in this study are rectangular-cross-sectioned type, hemi-sphere rooted type, and wedge type implant. The stress states of mandible with hemisphere rooted type implant and wedge type implant show similar levels, while those with sectioned rectangular implant results in higher stresses. It is suggested that the distance between the implant tip and cortical bone be kept far enough to prevent stress concentrations in the mandible.
인공고관절 전치환술에서 세라믹 볼 헤드의 기계적 안정성 평가를 위한 유한요소 해석
한성민,추준욱,전흥재,김정성,최귀원,윤인찬,Han, Sung-Min,Chu, Jun-Uk,Chun, Heoung-Jae,Kim, Jung-Sung,Choi, Kui-Won,Youn, In-Chan 대한의용생체공학회 2010 의공학회지 Vol.31 No.6
A ceramic articulating system in total hip replacement thought to be superior to metal-on-polyethylene due to its extremely low coefficient of friction and potential for high resistance to wear. But ceramic is brittle, which makes it mechanically and theoretically susceptible to fracture under certain mechanical conditions. In the current study, nine different models of ceramic ball heads were mechanically evaluated using 3D finite element(FE) analyses. It was found that the maximum stress in all ceramic models was lower than ceramic flexural strength, and it satisfied the requirements of the FDA Gaudience for artificial hip implant. Thus, ceramic ball head models introduced in the current study could be mechanically safe for clinical applications.
송강일,추준욱,서준교,최귀원,유선국,윤인찬,Song, Kang-Il,Chu, Jun-Uk,Suh, Jun-Kyo Francis,Choi, Kui-Won,Yoo, Sun-K.,Youn, In-Chan 대한의용생체공학회 2011 의공학회지 Vol.32 No.1
Cuff electrodes have a benefit for chronic electroneurogram(ENG) recording while minimizing nerve damage. However, the ENG signals are usually contaminated by electromyogram(EMG) activity from the surrounding muscle, the thermal noise generated within the source resistance, and the electric noise generated primarily at the first stage of the amplifier. This paper proposes a new cuff electrode to reduce the interference of EMG signals. An additional middle electrode was placed at the center of cuff electrode. As a result, the proposed cuff electrode achieved a higher signal-to-interference ratio compared to the conventional tripolar cuff. The cuff electrode was then assembled together with closure, headstage, and hermetic case including electronic circuits. This paper also presents a lownoise amplifier system to improve signal-to-noise ratio. The circuit was designed based on the noise analysis to minimize the electronic noise. The result shows that the total noise of the amplifier was below $1{\mu}V_{rms}$ for a cuff impedance of $1\;k{\Omega}$ and the common-mode rejection ratio was 115 dB at 1 kHz. In the current study, the performance of nerve cuff electrode system was evaluated by monitoring afferent nerve signals under mechanical stimuli in a rat animal model.
김기홍,이용찬,조병욱,권익찬,최귀원,배태수,Kim, Ki-Hong,Lee, Yong-Chan,Cho, Byoung-Ouck,Choi, Kui-Won,Kwon, Ick-Chan,Bae, Tae-Soo 대한구강악안면외과학회 2001 대한구강악안면외과학회지 Vol.27 No.1
With the object of providing a temporary artificial periodonal ligament-like membrane around the dental implant, 10 Branemark type implants were coated with commercially available chitosan(Fluka Co., Buchs, Switzerland) which has a molecular weight of 70,000 and 80% deacetylation degree. Once this bioactive hydrophillic polymer(chitosan) contacts with blood or wound fluids, it becomes swollen and penetrates into the adjacent cancellous bone. Thus the interface between implant and surrounding bone is completely filled with chitosan. This tight junction in early healing phase enhances primary stability. The chitosan coated dental implants were implanted into the fresh patella bones from porcine knees, since the thickness of cortical bone is relatively even and their cancellous structure is homogenous. To test the shock absorbing effect, 1mm delta-rogette strain gage was installed behind the implant. The results showed 1. The principal strain peak value directed to the impact of coated implant was 0.064 0.018(p<0.05) and that of uncoated implant was 0.095(0.032 p<0.05). 2. The peak time delay of coated implant was 0.056sec(0.011 p<0.05) and that of uncoated implant was 0.024sec(0.009 p<0.05). It can be reasoned from this results that the chitosan coating has a shock absorbing effect comparable with a temporary artificial periodontal ligament.
Cement Type 맞춤형 인공고관절의 설계 변수 변화에 따른 Cement 두께 변화와 이에 대한 응력 분석
박흥석,전흥재,윤인찬,이문규,서덕찬,최귀원,Park, Heung-Seok,Chun, Heoung-Jae,Youn, In-Chan,Lee, Moon-Kyu,Seo, Duck-Chan,Choi, Kui-Won 대한의용생체공학회 2006 의공학회지 Vol.27 No.6
The choice of suitable hip implant is one of important factors in the total hip arthroplasty (THA). In clinical view point, an improper adaptation of hip implant might induce abnormal stress distribution to the bone, which can shorten the lifespan of replaced hip implant. Currently, interest in the custom-designed hip implants has increased as studies reveal the significance of geometric shape of patient's femur in modeling and designing the implants. In this study, we have developed custom-designed hip implant models with various sizes, and analyzed the stress distribution in the bone and bone cement using the Finite Element Method. It was found that minimizing the gap between implant stem and femoral cavity is crucial to minimize the stress concentration in the bone.
유한요소법을 이용한 다양한 피질골 두께에서 6종의 골내임플랜트에 대한 수치적 연구
이용찬(Yong Chan Lee),조병욱(Byoung Ouck Cho),박영주(Young Ju Park),이영규(Young Kyoo Lee),최재봉(Jae Bong Choi),주원(Won Joo),최귀원(Kui Won Choi) 대한구강악안면외과학회 1999 대한구강악안면외과학회지 Vol.25 No.1
Dental implant is increasingly used to rehabilitate the masticatory function of missing teeth. Several types of dental implant have been desiened to give an optimal stress distribution to the surrounding bone, In this study, six types of implant were investigated using finite element methods 1) how the variation of cortical bone thickness affects the stress distribution in bony regions depending upon implant types, and 2) which type gives the best characteristics in the sense of stress distribution and stability. The hybrid-type implant with tapered cylinder and screw gave the optimum properties in view of stability and response due to variation of cortical bone thickness.