• Journal of the Korean Society for Precision Engineering
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• v.27 no.9
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• pp.52-57
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• 2010

The analysis of a crack in a bone-like material is performed numerically. The bone-like material is hierarchically structured and each hierarchy is structured by mineral platelets and protein matrix through staggered arrangement. Mechanical behavior of the composite can be analyzed using tension shear chain model. The Dugdale model is adopted to evaluate the fracture energy of Bone-like material. The fracture energy dissipation is assumed to concentrate within a strip near the crack tip along the prospective crack path. Fracture criterion of the bone-like material is estimated by using J integral. Effects of hierarchical level, ratio of elastic modulus of mineral to protein, aspect ratio of mineral platelet and volume fraction on J integral are investigated. It is found that the J integral decreases as elastic modulus ratio and hierarchy level increase. It is also shown that the J integral increases as the volume fraction and aspect ratio decrease.

• The Journal of Korea Robotics Society
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• v.11 no.4
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• pp.285-292
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• 2016

For articulated swimming robots, there have been no researches about controlling the motion or trajectory following. A control method for articulated swimming robot is suggested by extending a previous algorithm, ESPG (Extended Swimming Pattern Generator). The control method focuses on the situation that continuous pre-determined swimming pattern is applied for long range travelling. In previous studies, there has not been a way to control the propulsive force when a swimming pattern created by ESPG was in progress. Hence, no control could be made unless the swimming pattern was completed even though an error occurred while the swimming pattern was in progress. In order to solve this problem, this study analyzes swimming patterns and suggests a method to control the propulsive force even while the swimming pattern was in progress. The angular velocity of each link is influenced and this eventually modifies the propulsive force. However, The angular velocity is changed, a number of problems can occur. In order to resolve this issue, phase compensation method and synchronization method were suggested. A simple controller was designed to confirm whether the suggested methods are able to control and a simulation has affirmed it. Moreover, it was applied to CALEB 10 (a biomimetic underwater articulated robot) and the result was verified.

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.345-351
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• 2012

Biomimetic terpene sensors which have high sensitivity and stability have been fabricated using moleculary imprinted polymer (MIP) technology. Since it is impossible to make a resistive type sensor due to the high resistance of MIP, we improved the sensor by adding conductive polymers. We investigated the sensitivity of resistive type sensors with nano particles depending on the amount of conductive polymers. The MIP membrane contained the methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross linker, which formed specific cavities originated by the target terpene molecules. The mixture of MIP and the conductive polymer was coated on the patterns of interdigit electrodes on the alumina substrate. The fabricated sensors showed their highest specific sensitivities exposed to 500 ppm target gases : limonene 0.055 at 40% of amount of conductive polymers and geraniol $5.84{\times}10^{-4}$ at 20% of amount of conductive polymers. In conclusion, we found that the terpene sensors are affected by the target molecules, functional monomers and the conductive polymers.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.10
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• pp.928-933
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• 2012

In this paper, the IR and compass sensors for the underwater system were used. The walls of the water tank have been recognized and avoided treating the walls as obstacles by the bio-mimetic underwater robot. This paper is consists of two parts: 1.The hardware part for the IR and compass sensors and 2.The software part for obstacle avoidance algorithm while the bio-mimetic robot is swimming with the obstacle recognition. Firstly, the hardware part controls through the RS-485 communications between a microcontroller and the bio-mimetic underwater robot. The software part is simulated for obstacle recognition and collision avoidance based upon the data from IR and compass sensors. Actually, the bio-mimetic underwater robot recognizes where is the obstacle as well as where is the bio-mimetic robot itself while it is moving in the water. While the underwater robot is moving at a constant speed recognizing the wall of water tank as an obstacle, an obstacle avoidance algorithm is applied for the wall following swimming based upon the IR and compass sensor data. As the results of this research, it is concluded that the bio-mimetic underwater robot can follow the wall of the water tank efficiently, while it is avoiding collision to the wall.

• Journal of the Korean Ceramic Society
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• v.51 no.2
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• pp.103-106
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• 2014

Nacre is an organic-inorganic composite material; it is composed of $CaCO_3$ platelet and protein. The microstructure of nacre is a matrix that is similar to bricks and mortar. Technology inspired by nature is called biomimetic technology. In this study, to make high thermal conducting ceramic composite materials using biomimetic technology, a porous green body was prepared with BN platelets. PMMA was infiltrated into the porous green body to make a composite. The microstructure of the composite was observed with FESEM, and the thermal properties were measured. The thermal conductivity of the prepared organic-inorganic composite was 4.19 $W/m{\cdot}K$.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.573-579
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• 2006

Most of the recently developed robots are human friendly robots which imitate an animal or human such as entertainment robot, biomimetic robot and humanoid robot. Interest in these robots is increased because the social trend is focused on health, welfare, and graying. By these social backgrounds, robots become more human friendly and suitable or home or personal environment. The more biomimetic robots resemble living creature, the more human feels familiarity. Human feels close friendship not only when feeding a pet, but also when watching a pet having the food. Most of entertainment robots and pet robots use internal-type batteries and have a self-recharging function. Entertainment robots and pet robots with internal-type batteries are not able to operate during charging the battery. So far there have been a few robots that do not depend on an internal battery. However, they need a bulky energy conversion unit and a slug or foods as an energy source, which is not suitable for home or personal application. In this paper, we introduce a new biomimetic entertainment robot with autonomous eating functionality, called EPRO-1(Eating Pet RObot version 1). The EPRO-1 is able to eat a food (a small battery), by itself and evacuate. We describe the design concept of the autonomous eating mechanism of the EPRO-1, characteristics of sub-parts of the manufactured mechanism and its control system.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.3
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• pp.188-192
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• 2012

In this study, a carbon nanotube (CNT) flexible strain sensor was fabricated with CNT based epoxy and rubber composites for tactile sensing. The flexible strain sensor can be fabricated as a long fibrous sensor and it also may be able to measure large deformation and contact information on a structure. The long and flexible sensor can be considered to be a continuous sensor like a dendrite of a neuron in the human body and we named the sensor as a biomimetic artificial neuron. For the application of the neuron in biomimetic engineering, an ANMS (Artificial Neuron Matrix System) was developed by means of the array of the neurons with a signal processing system. Moreover, a strain positioning algorithm was also developed to find localized tactile information of the ANMS with Labview for the application of an artificial e-skin.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.731-734
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• 2005

Generally, characteristics of electromechanical actuators are coupled with the mechanical and the electrical properties. Important mechanical parameters of these actuators are the achievable force and displacement in the presence of electric field. These mechanical parameters are related to the stress and strain of the materials and the actuator geometry. This paper presents how to measure the blocked force by using the micro-balance. The blocked force is defined as the force produced by the transducer under an applied voltage when the tip is constrained to zero motion. Also, a theoretical force by using the cantilever beam model is calculated under elastic domain. From the sample of 4 cm $\times$ 1 cm $\times$ 20 $\mu$m, the blocked farce measured from the equipment is 20.3 $\mu$N at 8 V$_{DC}$. By comparing it with the theoretical value, 24.9 $\mu$N, the blocked force measurement is acceptable. The furce measurement is also investigated with different AC electric fields and the frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.735-738
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• 2005

Electro-Active Paper (EAPap) is attractive as an EAP actuator material due to its merits in terms of lightweight, dry condition, large displacement output, low actuation voltage and low power consumption. This paper presents the performance of EAPap actuators with thickness variation. The EAPap is made with cellulose paper, and is shown to bend in response to an external electric field. Up to the present, we have tested displacement, current and force of EAPap with 20 $\mu$m thickness. The thickness of EAPap is important factor that affects the performance of the actuator. Therefere, three different thickness of EAPap, 20, 30, and 40 $\mu$m are investigated that inference the tip displacement, blocked force, the resonance and the actuator efficiency. There is an optimum thickness of EAPap, which is resulted from the stiffness and the mass. The performance of EAPap with thickness is discussed.

• Prospectives of Industrial Chemistry
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• v.24 no.6
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• pp.19-31
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• 2021

자극응답성 액정 엘라스토머(liquid crystal elastomer)는 하이드로겔(hydrogel), 형상 기억 고분자(shape memory polymer)와 더불어 생체 특성을 모방한 인공 근육, 소프트 액추에이터 및 소프트 로봇을 위한 스마트 소재로 최근 높은 관심을 받고 있다. 특히, 액정 엘라스토머는 고무 탄성과 액정 이방성이 결합된 비등방성 탄성 고분자로, 열, 빛, 전기 및 수분과 같은 외부자극에 반응하여 가역적이며, 액정 분자들의 배향조절을 통한 프로그램된 변형이 가능하다. 액정 엘라스토머가 개념 증명을 하는 수준을 넘어 실제로 유용한 소프트 액추에이터 및 로봇 시스템에 적용되기 위해서는 우수한 구동력 및 작업 용량, 높은 구동 변형률, 빠른 응답 시간, 낮은 구동 온도, 다양한 외부 자극반응성 및 높은 에너지 전환 효율 등을 확보하는 것이 중요하다. 본 기고문에서는 액정 엘라스토머의 개념에 대해 소개하고, 이러한 소재가 소프트 액추에이터로써 광범위하게 활용될 수 있도록 다양한 성능들을 향상시킬 수 있는 방법에 대해 소개하고자 한다.