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김휘수(Hwi-Su Kim),박정준(Jung-Jun Park),송재복(Jae-Bok Song) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
In recent years, collision safety between humans and robots has drawn much attention since cooperation between humans and robots is increasingly needed in various fields. Since both positioning accuracy and collision safety are important, an industrial manipulator should maintain very high stiffness for positioning accuracy in the normal situation, but exhibit very low stiffness when subjected to a collision force greater than the injury tolerance. In order to achieve these requirements of an industrial manipulator, a safety mechanism composed of a linear spring and a double-slider mechanism was proposed in the previous research. To satisfy the operational requirements of an industrial manipulator, the spring stiffness of this safety mechanism was designed by conducting various dynamic analyses. Several experiments on static collisions show high stiffness of the safety mechanism against an external torque less than the pre-determined threshold torque, but the absorption of collision force when the external torque exceeds this threshold torque, thereby guaranteeing positioning accuracy and collision safety.
가변 가반하중을 포함하는 로봇의 필요토크 최소화를 위한 스프링 기반 가변 자중보상 메커니즘의 설계
김휘수,배명수,박찬훈,김두형,경진호,도현민,박동일,최태용,송성혁 제어·로봇·시스템학회 2020 제어·로봇·시스템학회 논문지 Vol.26 No.12
. Recently, with the increasing requirement of human-robot cooperation, robot safety has become an important issue in the robotics field. Counterbalance mechanisms were proposed as a solution to address this problem as it can ensure intrinsic safety and minimize the required torque of the actuators. However, previous counterbalance mechanisms were designed to compensate for the gravitational torque generated due to the weight of robots. Therefore, actuators should be selected to provide sufficient torque to support the payload. In this study, we propose a variable counterbalance mechanism for counterbalance mechanism improvement. The proposed mechanism can adjust the counterbalancing torque according to the weight of the payload attached at the end effector of the robot arm, such as a tool, gripper, or grasped object. Therefore, the torque required to support not only the self-weight of the robot arm but also any additional external load can be compensated effectively using the proposed variable counterbalance mechanism. Moreover, a 1 degree-of-freedom variable counterbalance arm was constructed to verify the effectiveness of the proposed mechanism. Various simulations and experimental results showed that the proposed variable counterbalance mechanism can effectively decrease the torque required to support the robot mass and payload. Hence, low-capacity actuators can be used for designing robots with desired specifications (e.g., maximum payload and repeatability) and safety.
Enhanced solubility of flavonoids through formation of nanocomplex with PEG for ocular diseases
심휘수,( Hye Sook Lee ),( Jae Wook Yang ),이해신 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Flavonoid is one of the polyphenolic molecule from natural species such as fruit and plant. Bio-inspired compound, catechin, is one of the component from green tea and other plants. Catechin as well as other flavonoids are generally known for their advantageous properties such as anti-inflammation, anti-oxidant, and anti-cancer effects. Many flavonoids are poorly soluble in water which is a critical drawback to be used in bio-applications. In this study, we increased aqueous solubility of catechin through formation of complex with poly(ethylene glycol) (PEG). The experimental procedure does not require chemical crosslinker or initiator. The preparation is simple but the solubility enhancement is high (at least 50 mg/ml). Nanocomlex of catechin is used in in-vivo to treat dry eye model. The nanocomplex showed anti-inflammation property and increased goblet cell density which helps dry eye diseases.