• Composites Research
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• v.23 no.4
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• pp.1-6
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• 2010

The dynamicresponse of biomimetic composites mimicking nacre under low velocity impact is investigated. The composites have hierarchical structures with a staggered pattern consisting of a protein and a mineral. To analyze the impact response of the composites, the finite element method is used. The effects of the hierarchical structures of the compositeson the dynamic response are examined. It is shown that the maximum stress, displacement and contact force in the composite subjected to low velocity impact decrease as the level of structural hierarchy increases.

• 기계와재료
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• v.23 no.4
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• pp.36-44
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• 2011

생체모방 경량 나노복합 에코소재기술은 자연계에 존재하는 물질의 구조를 모방하여 저온 저에너지 소모공정을 통하여 고경량 및 고강도를 갖는 나노복합체를 제조하는 친환경 신소재 기술이다. 고효율 저공해 성능에 초점을 맞추어 $CO_2$ 배출 및 지구온난화를 억제하고 웰빙사회에 적합한 차량을 개발하는 것이 현재 전세계 자동차회사들의 주된 관심사이다. 이러한 상황에 생체모방기술은 에너지 환경산업분야의 소재로 응용하는 원천기술로 기대된다. 이 생체모방기술은 자연 친화적 재료를 개발하여 하이브리드/전기 자동차의 내/외장재, 고효율 건축자재, 첨단 항공우주 신소재에도 응용이 가능하다. 최근에 보고된 생체모방 경량 나노 복합 에코소재 기술을 조사하였다.

• Composites Research
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• v.32 no.1
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• pp.50-55
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• 2019

In this study, we investigated the effect of fiber alignment in helicoidal structure on the mechanical properties of biomimetic fiber-reinforced composites. Using finite element analysis, circular biomimetic fiber composites were designed and studied. Various amounts of pressure loads were applied to a surface of the composites, and then bending and failure behaviors of the composites were analyzed. The results showed various failure morphologies according to the orientation of the fibers, and it turned out that the fiber alignment in helicoidal structure significantly improved the bending strength of the composite under pressure loading. This was because the fiber alignment in various directions for each layer dispersed effectively the fracture energy from the external load into multiple directions.

• 기계와재료
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• v.23 no.4
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• pp.46-58
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• 2011

홍합은 수중 환경에서 다양한 표면에 강하게 붙어서 자라는 수중 생물이며, 이러한 홍합의 특이적인 접착능력은 많은 연구자들에게 관심을 받고 있다. 홍합의 접착력에 관여하는 화학적 작용기를 모방한 폴리도파민/폴리노르에피네프린 표면 개질 기술은 자연의 홍합이 가지는 특성을 그대로 가지고 있어 수용액 상의 조건에서 표면의 성질에 관계없이 거의 모든 표면에 뛰어난 접착력을 나타낸다. 이러한 자연 모방 표면 개질 기술은 다양한 생체/에너지 재료, 신소재 복합 재료 등의 개발에 응용되고 있으며, 다양한 분야에서 활용될 수 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.108-115
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• 2020

In this study, the flexural performance of Highly Ductile Cement Composites(HDCC) mimicking boundary conditions of shellfish skin layer was evaluated. To improve ductility by mimicking the boundary skin layer structure of shellfish, the method of stratification by charging between precast panels using HDCC and the method of distributing PE-mesh to the interface surface were applied. Evaluation of flexural performance of layered cement composite materials mimicking boundary conditions of shellfish skin layer resulted in increased ductility of all test specimens applied with stratified cross-section compared to typical bending test specimens. The layered method by inserting PE-mesh showed excellent ductility. This is most likely because the inserted PE-mesh made an interface for separating the layers while the HDCC pillars in the PE-mesh gave adhesion between layers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1237-1238
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• 2011

• Journal of the Korean Society for Precision Engineering
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• v.29 no.11
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• pp.1245-1255
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• 2012

Effective elastic constants of biomimetic multilayer structures with hierarchical structures are evaluated based on the potential energy balance method. The effective anisotropic elastic constants are used in analyzing low-velocity impact of biomimetic multilayer structures consisting of mineral and protein. It is shown that displacements of biomimetic multilayer structures strongly depend on the volume fraction of mineral and hierarchical level. The effect of the volume fraction of mineral and hierarchical level on the contact force and stresses at the impact point are also discussed.

• Prospectives of Industrial Chemistry
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• v.23 no.2
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• pp.40-50
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• 2020

소프트 로봇의 수요와 관심이 증가함에 따라 생체 모방형 액추에이터 연구가 큰 관심을 받고 있다. 액추에이터란 외부 에너지를 기계적인 동작으로 변환하는 장치이며, 재료 자체가 유연하여 부드러운 움직임을 재현할 수 있는 소프트 액추에이터의 연구가 활발히 진행되고 있다. 고분자 연성 재료 중에 하나인 하이드로겔은 90% 이상이 물로 구성되어 있기 때문에 생체 친화적이면서 동시에 환경 친화적인 재료이며 이를 기반으로 한 액추에이터 연구가 새로이 각광받고 있다. 최근에는 하이드로겔 액추에이터의 성능 향상을 위해 나노재료를 하이드로겔에 첨가하는 연구가 진행되고 있으며, 나노재료가 갖는 고유의 특성을 활용함으로써 하이드로겔 액추에이터의 자극 감응성 향상, 변형 방향의 제어, 높은 변형 효율 그리고 기계적 물성 증가가 보고되고 있다. 이는 헬스케어를 위한 웨어러블 장치, 재활을 목적으로 한 인공 근육 등에 적용이 가능하다. 본 기고문에서는 자극 감응성 고분자와 나노재료를 이용한 하이드로겔 액추에이터 연구에 대해 자극(전기장, 빛, 열, 자기장)의 종류에 따라 분류하여 소개하고, 합성 전략 및 구동 원리에 대해 간략하게 설명하고자 한다.

• Composites Research
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• v.37 no.4
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• pp.247-264
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• 2024

Recent advances in electro-active polymer (EAP) actuators, owing to their flexibility, lightweight, and simple fabrication process, have showcased their high utility across various fields such as soft robotics, biomimetics, wearable devices, and haptic technologies. Moreover, EAP actuators are evolving into smart devices with new functions and characteristics through the integration of functional materials and innovative technologies. This paper categorizes EAPs into ionic EAPs and electronic EAPs. Ionic EAPs include, most notably, ionic polymer-metal composites (IPMCs) and conducting polymers (CPs), while electronic EAPs encompass dielectric elastomer actuators (DEAs), ferroelectric polymer actuators, and the recently introduced hydraulically amplified self-healing electrostatic (HASEL) actuators. Detailed explanations based on the latest research are provided concerning the mechanism, structure, performance improvement strategies, methods for adding functionality, and application areas for each type of actuator.

• Composites Research
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• v.20 no.3
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• pp.50-54
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• 2007

The Ionic Polymer Metal Composite (IPMC), an electro-active polymer, has many advantages including bending actuation, low weight, low power consumption, and flexibility. These advantages coincide with the requirements of a bio-related application. Thus, IPMC is promising materials for bio-mimetic actuator and sensor applications. Before applying IPMC to actual application, basic mechanical properties of IPMC should be studied in order to utilize IPMC for practical uses. Therefore, IPMCs are fabricated to investigate the mechanical characteristics. Nafion is used as a base ionic polymer. Mason samples cast with various thicknesses are used to test the thickness effects of IPMC. Subsequently, IPMC is fabricated using the chemical reduction method. The deformation, blocking force and frequency response of the IPMC actuator are important properties. In this present study, the performances of the IPMC actuators, including the deformation, blocking force and natural frequency, are then obtained according to only the input voltage and IPMC dimensions. Finally, the empirical performance model and the equivalent stiffness model of the IPMC actuator are established using experiments results.