• 생명과학회지
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• 제14권3호
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• pp.484-489
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• 2004

인공관절은 21세기 정형외과 발전의 주요변화들 중의 하나이다. 1997년이래 전 세계적으로 무릎인공관절(Total Knee Arthroplasty: TKA)을 사용하는 사람들이 해마다 약 600,000명씩 증가하고 있는 추세이고 미국에서만 인공관절을 사용하고 있는 사람들이 210,000명에 달하고 있으며 그 시장은 대략 $5 billion을 넘고 있다(7). 무릎인공관절은 일상생활에서 의자에 앉았다 일어날 때 계단을 올라 갈 때 등, 무릎의 근 모멘트가 적당한 활동을 해서 무릎관절 근육에 지레와 같은 작용을 하게 하고, 완전한 무릎으로 정상인의 무릎과 같은 기능을 오랫동안 유지하게 한다. 이러한 목적을 달성하기 위해서는 무릎인공관절 디자인 시 정상적인 무릎 회전축(normal knee's axes of rotation)들의 정확한 위치를 파악하는 것은 중요하다. 인공관절 수술 후 무릎관절의 신전과 굴곡 운동을 하는 동안 하나의 회전축(single-axes)을 가진 하나의 회전 반경(single-radius)을 알아보는 것은 여러 축(multi-axes)으로 움직이게 된다는 다축 회전반경(multi-radius)을 분석하기에 앞서 중요한 연구이다. 따라서 본 연구에 서는 무릎이 신전운동과 굴곡 운동 시 신전과 굴곡 모멘트를 만들어내는 대퇴 사두근(quadriceps muscle)과 무릎 오금근 (hamstring)의 역할을 알아보았고, 또한 모멘트와 대퇴 사두근의 iEMG 형태를 파악하였다. 본 연구를 수행하기 위해 무릎인공관절 수술을 받고 1년과 3년이 지난 정상적인 생활을 하는 피검자(1년2명, 3년2명)를 대상으로 Isometric 테스트를 위한 KIN-COM III을 사용하여 60$^\circ$, 30$^\circ$의 무릎굴곡 측정을 하였고, Isokinetic concentric 테스트를 위해서 무릎굴곡각도의 $10^\circ$-80$^\circ$까지 움직임을 측정하였다 또한 15$^\circ$-75$^\circ$까지의 신전운동(sit-to-stand movement)과 굴곡운동(stand-to-sit movement)을 실시하여 시간의 차이, 내전과 외전의 차이 그리고 iEMG의 차이를 알아보았다. 본 연구의 데이터는 여러 번의 실험을 통하여 가장 일반적인 수치를 사용하였다. 이 때 16-channel BTS TELEMG를 사용하여 대퇴사두근과 무릎오금근의 근육활동모양을 알아보았다. 본 연구결과는 시술 후 3년이 지나면서 TKR (Total Knee Replacement)의 대퇴 사두근 토큐가 약해지는 것으로 나타났고, iEMG 실험에서는 N-TKR (Non-Total Knee Replacement)의 대퇴 사두근이 TKR의 대퇴 사두근 보다 근 수축력이 더 크게 발휘되는 것으로 밝혀졌다. 단축회전반경의 굴곡과 신전의 $10^\circ$-80$^\circ$까지의 각 속도는 굴곡동작이 1.19s, 신전 동작이 1.68s로 나타났다. 굴곡과 신전동작에서 다리의 외전(abduction)의 각도변화는 굴곡 시 5.5$^\circ$, 신전 시 5.2$^\circ$로 나타났고, 내전(adduction)의 각도변화는 굴곡 시 7.2$^\circ$, 신전 시 6.1$^\circ$로 나타났다. 대퇴 사두근의 iEMG변화에서는 15$^\circ$-60$^\circ$까지 vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF) 모두 굴곡동작에서 큰 값으로 나타났고, 61$^\circ$-75$^\circ$사이에서는 신전동작에서 iEMG가 큰 값으로 나타났다. 이와 같은 결과들은 인공관절 수술자들의 다축회전 반경을 분석하기에 앞서 중요한 선행연구가 될 것으로 생각된다.

• Journal of Biosystems Engineering
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• 제1권1호
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• pp.1-6
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• 1976

This paper is the third one of the study on balanced type oscillating mole-drainer, the first one was presented in No 9. Gyeongsang College Report and the second one in Vol. 17, No.4 of the KSAE. In the first part of this study, the characteristics of traction forces between the nonoscillating earth working equipments and oscillating ones was compared. A model of the balanced type oscillating mole-drainer, which composed of a mechanism that may reduce the machine vibration, was designed following the dimensional analysis and similitude technique. The model test was carried out to clarify the balancing mechanism of the oscillating parts and other parts of the machine. In the light of the results from the model tests, a prototype machine was made for experimental purpose. Results from the field test by a reported in the near future. In the second report, the model tests were carried out under the same soil conditions, i.e, . oscillating frequency, running velocity, and oscillating amplitude, etc. It was clear that use of balanced type oscillating model could substantially reduce the vibration of the whole system of the machine, when compared with the nonoscillating type model. In this paper(the third report), results of investigation on the traction force, power requirement, and moment. etc, is presented. Analysis of variance technique was used for analyzing the effect of the frequency, amplitude, and running velocity on the draft force, torque, power requirements, and moments. The results obtained from the model tests are as follows, 1) By practicing a balanced-type oscillating mole-drainer, it was possible to reduce the traction resistance by 55.1-61. 2 percent of traction resistance, however, was 1.75 - 1.95 times greater than the value of resistance which was induced by use of a mole-drainer with single bullet. The resistance of rear shank against soil was considered as a main causing factor of the above results. 2) As the oscillation frequency was increased, the traction resistance was decreased. Considering on the effect of oscillation the greater the amplitude, and the slower the running velocity was, the greater the reduction ratio of traction resistance was. 3) The ratio of the traction resistance of oscillating mole-drainer to that of non-oscillating one could be represented as a function of dimensionless variable (V/$Af$). The results from the tests were well agreed with the reported results from the experim ents on oscillation plow or hoe. 4) By taking a lower value of (V/$Af$), reducing the traction resistance was possible. This fact meant, however, that the efficiency of mole drain practice would be lower. 5) It was experimentally confirmed under the same condition of soil that the variable (R/$rD1^3$) could be represented as a function of a variable($V^2/gD$) when a non\ulcornerocillating mole-drainer was used. 6) When a oscillating mole-drainer was used, the variable(R/$rD_1^{3}$) could be represented as a function of two variables ($v^2/gD_1$) and (V^2/gD_1$). 7) The torque was not affected by a change of frequency. However, a relation of proportionality existed between torque and amplitude, running velocity, and ratio of bullet diameter. When a balanced type oscillating mole-drainer with two bullets was used, torque was increased by 52.8-78. 4 percent and total power requirement was also increased. 8) Total power requirement was increased linearly in accordance with the increasing frequency, 41.96 percent of total power was used for oscillating action. The magnitude of total power requirement was 1. 8-9. 4 times greater than that of a non-oscillating mechanism. In the view point of power requirement, it was not advisable to increase the frequency, amplitude, running velocity, and ratio of bullet diameter at the same time. 9) Only the positive moment occured in the rear shank. Change of the diameter of a rear bullet, could not affect the balancing against the soil resistance. It was necessary for rear bullet to have a large resistance against soil only when the rear bullet was in backward motion. 10) Within an extent of the experimental base, optimum limits for several design factors were A=0.5cm, $f$=22.5Hz, V=O. 05m/sec, and $\lambda$=1.0 By adapting these values traction resistance was reduced by 40 percent and vibration acceleration wa s reduced by 60 percent. Even though the total , power requirements for operating a balanced type oscillation mechanism was greater ~than that of non-oscillating one, using a oscillating mechanism would be more effective. Because a balanced type oscillating mechanism is used, tractive resistance will be reduced and then the lighter . tractive equipment could be used.