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하지강성 가변 인공건 액추에이터(Leg Stiffness controllable Artificial Tendon Actuator, LeSATA™)의 개발
한기봉(Gi-Bong Han),어은경(Eun-Kyung Eo),지대원(Dae-Won Jee),양영규(Young-Gyu Yang),김철웅(Cheol-Woong Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
If we can design a knee actuating mechanism as a primary actuator for supporting knee extension, it might be possible to revolutionarily store or release elastic strain energy, which is consumed during the gait cycle, and as a result leg stiffness is expected to increase. In this case, it is necessary to design an ankle actuating mechanism as a secondary actuator which will adjusted excessive artificial leg stiffness from the primary actuator by reserving or releasing the elastic strain energy, because the energy, which is a part of kinetic and potential energy generated by human walking and is temporarily reserved in collision phase, will be discharged in rebound phase of elastic recoil. Dissimilar to previous study, we assumed that the leg stiffness could be increased by controlling walking speed with relative angular velocity of two segments and accordingly we are currently developing a knee-ankle two actuator system. As mentioned above, however, the artificial knee actuating will generate a new compensatory mechanism in the ankle part. It suggests that excessive leg stiffness caused by the artificial knee actuating will lead to a stumbling gait in abnormal collision phase accompanied by foot touch-down. Therefore, in designing the actuators we also considered the increase in walking speed and stumbling from repetitive acceleration in swing phase of previous gait cycles, satisfying the conditions with regard to relative angular velocity of two segments, thigh and shank, in order to raise leg stiffness. Furthermore, it might be difficult to confirm the effectiveness of the actuators if kinematic energy from unnecessary human walking is released under artificial deceleration control, which was designed to prevent an increase in walking speed. Therefore, we believed that the solution for the compensatory mechanism in ankle joint would be conversely derived by confirming the effect of changes in metatarsophalangeal joint tilt angle and walking speed on knee movement. Accordingly, we invented a new generation leg stiffness actuator in order to avoid the stumbling gait from the ankle joint compensatory mechanism caused by leg stiffness. The trademark of the device is called Leg Stiffness Artificial Tendon Actuator (LeSATA™). The stiffness between two springs could be variably controlled by adding eccentric mass inside the actuator, LeSATA. We also verify the functionality of the actuator which will automatically transfer between walking and running mode by actively monitoring any changes in gait pattern of LeSATA™ and in relative angular velocity between thigh and shank.
하지강성 가변 인공건 액추에이터(LeSATA<sup>®</sup>)의 개발 Part I - Metatarsophalangeal Joint Tilt Angle의 보행분석 -
한기봉,어은경,오승현,이순혁,김철웅,Han, Gi-Bong,Eo, Eun-Kyung,Oh, Seung-Hyun,Lee, Soon-Hyuck,Kim, Cheol-Woong 대한기계학회 2013 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.1 No.2
기존의 보행분석 연구들은 하지를 하나의 스프링으로 간주하였다. 만약 슬관절 신전을 보조할 수 있는 슬관절 액추에이팅 메커니즘을 개발할 수 있다면 보행에 필요한 탄성-변형률에너지를 혁신적으로 저장-방출할 수 있고, 그 결과 보행 중 하지강성은 더욱 증가할 것이다. 게다가 족관절 액추에이팅 메커니즘까지 추가되어 있다면 슬관절 액추에이터에 의한 과도한 인공하지강성을 능동적이고 적절한 수준으로 보상해주는 기전으로 작동할 것이다. 만약 가속도에 의한 보행속도 증가를 방지하기 위해 인위적 감속통제를 작동시킨다면 불필요한 운동에너지의 방출이 발생되고 하지강성 액추에이터의 실효성은 의심을 받게 된다. 따라서 본 저자는 보행속도를 2개의 세그먼트에 의한 상대 각속도 조절기법을 이용하여 하지강성을 증가시킨다는 기본개념으로 슬-족관절 액추에이터 시스템을 개발하였다. 또한 족관절에 슬관절 액추에이팅에 대한 보상기전이 존재하는 경우, 족관절의 보상기전이 중족지절관절 경사각 및 보행속도 변화에 미치는 상호영향을 연구하였다. The established gait analysis studies have regarded leg as one single spring. If we can design a knee-ankle actuating mechanism as a primary actuator for supporting knee extension, it might be possible to revolutionary store or release elastic strain energy, which is consumed during the gait cycle, and as a result leg stiffness is expected to increase. An ankle joint actuating mechanism that stores and releases the energy in ankle joint is expected to support and solve excessive artificial leg stiffness caused by the knee actuator (primary actuator) to a reasonable extent. If unnecessary kinematic energy is released with the artificial speed reduction control designed to prevent increase in gait speed caused by increase in time passed, it naturally brings question to the effectiveness of the actuator. As opposed to the already established studies, the authors are currently developing knee-ankle two actuator system under the concept of increasing lower limb stiffness by controlling the speed of gait in relative angular velocity of the two segments. Therefore, the author is convinced that compensatory mechanism caused by knee actuating must exist only in ankle joint. Ankle joint compensatory mechanism can be solved by reverse-examining the change in metatarso-phalangeal joint (MTPJ) tilt angle (${\theta}_1=0^{\circ}$, ${\theta}_2=17^{\circ}$, ${\theta}_3=30^{\circ}$) and the effect of change in gait speed on knee activity.
슬관절 수술용 전기소작완드에 적용되는 형상기억합금 코일스프링의 회복력 및 행정거리의 관계
양영규(Young-Gyu Yang),한기봉(Gi-Bong Han),김철웅(Cheol-Woong Kim) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.12
슬관절 소작용 완드(Electrosurgical Knee Wand, EKW)는 고주파 소작법으로 슬관절 인대, 조직 등의 응고, 삭마, 절제, 등에 적용된다. EKW와 radiofrequency를 이용한 조직응고, 삭마 등의 슬관절 수술에서 수술안전성, 편의성 및 성공률을 극대화하기 위해서는 병변에 매우 정확하고 안전하게 EKW가 선택적 접근을 할 수 있도록 유도하는 탁월한 방향조종제어능이 핵심기술이다. 따라서 본 연구에서는 대퇴경골부 제한적인 공간에서 가장 적합한 수술용 의료기기 액추에이터로 판단되는 형상기억합금(SMA) 와이어를 이용하여 형상기억효과를 극대화할 수 있는 SMA 인장스프링 모델을 제작하여 실험을 수행하였다. 또한 SMA의 열전기적 특성 및 전류변화에 따른 온도특성에 대한 연구를 수행하고 SMA 인장스프링의 설계조건에 따른 회복력 및 행정거리의 관계를 평가하였다. 그 결과, SMA 인장스프링의 직경이 작아질수록 최대온도는 증가하였다. 전류인가 15초의 경우는 전류량 증가와 힘의 증가가 비례한 반면 전류인가 30초는 매우 불안정한 결과가 나타났다. 반면, 전류량 증가와 행정거리(TS) 증가 관계는 전류인가 15초일 때가 전류인가 30초일 때보다 더 안정적인 결과가 나타났다. Electrosurgical knee wand (EKW) is a high-frequency thermocautery instrument and is often used for coagulation, ablation, excision, and extirpation of knee ligaments and tissues. In order to maximize the success rate, ease, and safety of knee surgery using EKW and radiofrequency ablation, it is necessary to ensure that the EKW selectively approaches the lesion with utmost accuracy and safety. The key feature of this instrument is its excellent maneuverability. Hence, the authors constructed a tensile spring model based on a shape memory alloy (SMA), which exhibits the shape memory effect. This model can be used in knee surgery as it is considered the most biocompatible femorotibial surgical actuator. The changes in external temperature with current and the thermoelectric characteristics of the SMA were investigated. The relationship between the restoring force and the typical stroke (TS) in response to the conditions in the SMA tensile spring design were evaluated. In conclusion, as the diameter of the SMA tensile spring decreased, the maximum temperature increased. The strain in the actuator caused a stable and proportional increase in the force and induced current for up to 15s, but this increase became very unstable after 30s. Moreover, the relationship between the current and the TS was more stable than that between the current and the restoring force.
생체분해성 폴리카프로락톤 문합커플러의 사출성형조건에 따른 수축률 및 결합강도의 미세변화
안근선(Geun-Seon Ahn),한기봉(Gi-Bong Han),오승현(Seung-Hyun Oh),김철웅(Cheol-Woong Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The use of mechanical anastomosis coupler instead of sutures has been increasing in microvascular anastomosis surgery. However, non-biodegradable anastomosis coupler has problems such as not only inflammatory reaction but also remaining permanently in injured the human body. Therefore, we fabricated biodegradable anastomosis coupler using injection molding process to overcome the limitation of non-biodegradable anastomosis coupler. In various injection molding process conditions, the shrinkage were calculated with different cylinder temperatures and injection molding pressures and anastomosis strength was measured. Resulting in shrinkage calculation, the shrinkage change to hole part was higher than that to pin part. The shrinkage was increased according to cylinder temperature increase and decreased according to injection molding pressure increase. Resulting in degradation test, water uptake was increased and molecular weight was decreased and then mass loss of biodegradable anastomosis coupler occurred.
근위경골절골술(HTO)에 적용되는 X-band 플레이트의 경골틈새각(TGA)이 경골힌지의 인장강도에 미치는 영향
조문정(Moon-Jung Cho),황정훈(Jung-Hoon Hwang),한기봉(Gi-Bong Han),박종규(Jong-Kyu Park),김철웅(Cheol-Woong Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
The mechanical behavior of polymeric materials, HDPE depends on both time and temperature. The study of deformation behavior at different strain rates is important in engineering design such as X-band plate. Because mechanical properties and deformation mechanisms are strongly dependent on the applied strain rate. Generally the deformation behavior of polymeric materials based on engineering stress-strain curve is complex because of highly inhomogeneous nature of plastic deformation in particular necking. Therefore we tried to determine about mechanical behavior of HDPE in this study. Normally, tensile, compression, and impact testing under various strain rates of polymeric materials have been trying to determine the mechanical behavior. Since a method of tensile test is easy to test, so it is often used to evaluation of it. We performed tensile test by various strain rates(1 to 500%/min) in order to appreciate viscoelastic behavior on increasing strain rate. Tensile stress-strain curve was induced from the data and then we marked the point of transition to calculate transition stress, strain, and modulus.
평막을 이용한 정수처리용 정밀여과 막분리 시스템에서 최적 운전인자 도출에 관한 연구(1)
김지훈 ( Kim Ji Hun ),김형수 ( Kim Hyeong Su ),염익태 ( Yeom Ig Tae ),한기봉 ( Han Gi Bong ) 한국물환경학회 2003 한국물환경학회지 Vol.19 No.6
The permeability of membrane filtration system depends on characteristics of the raw water and operating conditions. The purpose of this study was to determine the optimum operation parameters for water treatment using plate type MF membrane(pore size 0.22㎛). The pilot microfiltraion(MF) membrane separation system had been operated in a dead-end filtration mode and applied to actual Pal-dang raw water. The experimental results are shown as follows; (1)permeate flux 30LMH was determined the optimum operation condition, (2)the chemical cleaning efficiency was only found to be 100% using H₂SO₄+NaOCl, (3)the removal efficiencies of SS and turbidity were found to be almost 100%. However, The removal efficiencies of UV_(260) and DOC were 30% and 13%, respectively. Also, in order to improve the permeate flux and the removal efficiency of dissolved organic matter, granular activated carbon system should be added to the MF membrane System.