• Journal of Institute of Control, Robotics and Systems
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• v.19 no.9
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• pp.782-790
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• 2013

In this paper, we propose a better solution for swimming plans of an articulated underwater robot, Crabster, with a view point of biomimetics. As a biomimetic model of underwater organisms, we chose diving beetles structurally similar to Crabster. Various swimming locomotion of the diving beetle has been observed and sorted by robotics technology through experiments with a high-speed camera and image processing software Image J. Subsequently, coordinated patterns of rhythmic movements of the diving beetle are reproduced by simple control parameters in a parameter space which make it easy to control trajectories and velocities of legs. Furthermore, a simulation was implemented with an approximated model to predict the motion of the robot under development based on the classified forward and turning locomotion. Consequently, we confirmed the applicability of parameterized leg locomotion to the articulated underwater robot through the simulated results by the approximated model.

• Smart Structures and Systems
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• v.5 no.2
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• pp.139-152
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• 2009

Globally, civil infrastructures are deteriorating at an alarming rate caused by overuse, overloading, aging, damage or failure due to natural or man-made hazards. With such a vast network of deteriorating infrastructure, there is a growing interest in continuous monitoring technologies. In order to provide a true distributed sensor and control system for civil structures, we are developing a Structural Nervous System that mimics key attributes of a human nervous system. This nervous system is made up of building blocks that are designed based on mechanoreceptors as a fundamentally new approach for the development of a structural health monitoring and diagnostic system that utilizes the recently developed piezo-fibers capable of sensing and actuation. In particular, our research has been focused on producing a sensory nervous system for civil structures by using piezo-fibers as sensory receptors, nerve fibers, neuronal pools, and spinocervical tract to the nodal and central processing units. This paper presents up to date results of our research, including the design and analysis of the structural nervous system.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.366-366
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• 2016

Nanoscale observation of attachment systems of animals has revealed various exquisite multiscale architectures for essential functions such as gecko's locomotion, beetles' wing fixation, octopuses' sucking and crawling. In particular, the hierarchical 3-dimensional hexanonal nano-architectures in the tree frog's adhesion is known to have the capability of the enhancement of adhesion forces on the wet or rough surfaces due to the conformal contacts against rough surfaces and water-drainable micro channels. Here, we report that tree frog-inspired patches using unique artificial 3-dimensional hexagonal structures can be exploited to form reversibly enhanced adhesion against various highly curved and rough surfaces in dry and wet condition. To investigate the adhesion effect of micro-channels, we changed the arrangement of microstructure and spacing gaps between micro-channels. In addition, we introduced the 3-dimensional hexagonal hierarchical architectures to artificial patches to enhance to conformal contacts on the various rough surfaces such as skin and organs. Using the robust adhesion properties, we demonstrated the self-drainable and comfortable skin-attachable devices which can measure EKG (electrokardiogramme) for in-vitro diagnostics. As a result, bio-inspired programmable nano-architectures can be applied in versatile devices such as, medical patches, skin-attachable electronics etc., which would shed light on future smart, directional and reversible adhesion systems.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.21-26
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• 2013

In this paper, we introduced various 3D printing technology and it's application on tissue engineering and regenerative medicine. Using the 3D printing technology, Korea Institute of Machinery and Materials (KIMM) has developed 3D bio-printing system. Various 3D tissue engineered scaffolds have been fabricated by the 3D bio-printing system. Cell printing system has been also developed and it is the fundamental technology for organ regeneration in tissue engineering and regenerative medicine.

• Smart Structures and Systems
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• v.3 no.4
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• pp.495-505
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• 2007

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.103-110
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• 2020

Bio-inspired underwater robots have been studied to improve the dynamic performance of fins, such as swimming speed and efficiency, which is the most basic performance. Among them, bio-inspired soft robots with a compliant tail fin can have high degrees of freedom. On the other hand, to improve the driving efficiency of the compliant fins, the stiffness of the tail fin should be changed with the driving frequency. Therefore, a new type of variable stiffness mechanism has been developed and verified. This study, which was inspired by the anatomy of a real dolphin, assessed a process of designing and manufacturing a robotic dolphin with a variable stiffness mechanism. By mimicking the vertebrae of a dolphin, the variable stiffness driving part was manufactured using subtractive and additive manufacturing. A driving tendon was placed considering the location of the tendon in the actual dolphin, and the additional tendon was installed to change its stiffness. A robotic dolphin was designed and manufactured in a streamlined shape, and the swimming speed was measured by varying the stiffness. When the stiffness of the tail fin was varied at the same driving frequency, the swimming speed and thrust changed by approximately 1.24 and 1.5 times, respectively.

• Journal of the Korean Ceramic Society
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• v.51 no.1
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• pp.7-10
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• 2014

Abalone shell is composed of 95 wt% $CaCO_3$ platelets and 5 wt% of a protein-rich organic matrix which acts as an adhesive layer, connecting aragonite tablets, thus maintaining the structural integrity of the composite. By mimicking abalone shell, we prepared a silicate plate/polymer nanocomposite by infiltrating PMMA between silicate layers and warm-pressing them at $200^{\circ}C$ for 1 h under 15 tons to make organic-inorganic composite materials. To examine the organic-inorganic composite materials after the warm-pressing procedure, the composite sample was analyzed with FE-SEM and TG. The bending strengths and densities of the composites prepared by a silicate plate and PMMA after the warm-pressing process were ~140 MPa and 1.5, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.5
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• pp.357-362
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• 2016

Various species of insects display vivid colors, widely known as 'structural color' due to their optical interference. Morpho butterflies are famous for their brilliant iridescent colors, which arise from the photonic-nanostructures of optical interference on their wings. In this paper, we outline the results of a comparative study of the optical properties of bio-inspired Morpho butterfly structures with the widely known Distributed Bragg Reflector (DBR), conducted using a rigorous coupled-wave analysis (RCWA) method for the two structures. Almost analogous tendencies were observed for both Morpho and DBR structures. With variation in the surrounding media, however, Morpho structures showed an obvious peak shift while no significant changes were observed in DBR, which can be applicable.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.202-202
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• 2011

The research of 3-dimensional (3-D) scaffold for tissue engineering has been widely investigated as the importance of the 3-D scaffold increased. 3-D scaffold is needed to support for cells to proliferate and maintain their biological functions. Furthermore, its architecture defines the shape of the new bone and cartilage growth. Polycaprolactone (PCL) has been one of the most promising materials for fabricating 3-D scaffold owing to its excellent mechanical property and biocompatibility. However, there are practical problems for using it, in vitro and in vivo; extracellular matrix components and nutrients cannot penetrate into the inner space of scaffold, due to its hydrophobic property, and thus cell seeding and attachment onto the inner surface remain as a challenge. Thus, the surface modification strategy of 3-D PCL scaffold is prerequisite for successful tissue engineering. Herein, we utilized a mussel-inspired approach for surface modification of 3-D PCL scaffold. Modification of 3-D PCL scaffolds was carried out by simple immersion of scaffolds into the dopamine solution and stimulated body fluid, and as a result, hydroxyapatite-immobilized 3-D PCL scaffolds were obtained. After surface modification, the wettability of 3-D PCL scaffold was considerably changed, and infiltration of the pre-osteoblastic cells into the 3-D scaffold followed by the attachment onto the surface was successfully achieved.

• Smart Structures and Systems
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• v.7 no.3
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• pp.223-228
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• 2011

An understanding of biomaterials' smart properties and how biocomposite materials are manufactured by cells provides not only bio-inspiration for new classes of smart actuators and sensors but also foundational technology for smart materials and their manufacture. In this case study, I examine the unique smart properties of bone, which are evident at multiple length scales and how they provide inspiration for novel classes of mechanoactive materials. I then review potential approaches to engineer and manufacture bioinspired smart materials that can be applied to solve currently intractable problems such as the need for "smart" body armor or decor cum personal safety devices.