Kwang Joon Yoon

Bio: Kwang Joon Yoon is an academic researcher from Konkuk University. The author has contributed to research in topics: Actuator & Unimorph. The author has an hindex of 20, co-authored 120 publications receiving 1384 citations. Previous affiliations of Kwang Joon Yoon include Samsung.

Analytical design model for a piezo-composite unimorph actuator and its verification using lightweight piezo-composite curved actuators

Abstract: This paper describes an analytical design model for a layered piezo-composite unimorph actuator and its numerical and experimental verification using a LIPCA (lightweight piezo-composite curved actuator) that is lighter than other conventional piezo-composite type actuators. The LIPCA is composed of top fiber composite layers with high modulus and low CTE (coefficient of thermal expansion), a middle PZT ceramic wafer, and base layers with low modulus and high CTE. The advantages of the LIPCA design are to replace the heavy metal layer of THUNDER by lightweight fiber-reinforced plastic layers without compromising the generation of high force and large displacement and to have design flexibility by selecting the fiber direction and the number of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use a resin prepreg system. A piezo-actuation model for a laminate with piezo-electric material layers and fiber composite layers is proposed to predict the curvature and residual stress of the LIPCA. To predict the actuation displacement of the LIPCA with curvature, a finite element analysis method using the proposed piezo-actuation model is introduced. The predicted deformations are in good agreement with the experimental ones.

Design and demonstration of a biomimetic wing section using a lightweight piezo-composite actuator (LIPCA)

Abstract: This paper describes the design and evaluation of biomimetic wing sections, where the trailing edges of the wing sections are actuated by the piezoceramic actuator LIPCA (lightweight piezo-composite actuator). Thermal analogy based on linear elasticity was used for the design and analysis of the wing sections. In the actuation test of the wing sections, the effective deflection angle of the trailing edge was approximately five degrees at 300 V input. The predicted and measured actuation displacements agreed very well up to an input of 150 V. However, the real actuation displacement became larger than the estimated value for higher input voltages due to the material non-linearity of the lead zirconate titanate (PZT) wafer in the LIPCA. The biomimetic wing sections can be used for control surfaces of small scale unmanned aerial vehicles (UAVs).

Curved shape actuator device composed of electro active layer and fiber composite layers

Abstract: The piezo-composite curved actuator of the present invention comprises a piezoelectric layer (10), a lightweight fiber-reinforced lower composite layer (20) with a high CTE (coefficient of thermal expansion) and a low modulus, which is placed under the piezoelectric layer, a lightweight fiber-reinforced upper composite layer (30) with a low CTE and a high modulus, which is placed on the piezoelectric layer, and an insulator layer (23) placed between the piezoelectric layer and the upper composite layer. The piezo-composite curved actuator may further comprise an insulator layer (24) placed on the upper composite layer. Also, the piezo-composite curved actuator may further comprise insulator layers (22) placed between the insulator layer (23) and the lower composite layer (20) at the both sides of the piezoelectric layer (10).

Computer vision : a modern approach = 计算机视觉 : 一种现代的方法

Abstract: From the Publisher: The accessible presentation of this book gives both a general view of the entire computer vision enterprise and also offers sufficient detail to be able to build useful applications. Users learn techniques that have proven to be useful by first-hand experience and a wide range of mathematical methods. A CD-ROM with every copy of the text contains source code for programming practice, color images, and illustrative movies. Comprehensive and up-to-date, this book includes essential topics that either reflect practical significance or are of theoretical importance. Topics are discussed in substantial and increasing depth. Application surveys describe numerous important application areas such as image based rendering and digital libraries. Many important algorithms broken down and illustrated in pseudo code. Appropriate for use by engineers as a comprehensive reference to the computer vision enterprise.

A carbon nanotube strain sensor for structural health monitoring

Abstract: A carbon nanotube polymer material was used to form a piezoresistive strain sensor for structural health monitoring applications. The polymer improves the interfacial bonding between the nanotubes. Previous single walled carbon nanotube buckypaper sensors produced distorted strain measurements because the van der Waals attraction force allowed axial slipping of the smooth surfaces of the nanotubes. The polymer sensor uses larger multi-walled carbon nanotubes which improve the strain transfer, repeatability and linearity of the sensor. An electrical model of the nanotube strain sensor was derived based on electrochemical impedance spectroscopy and strain testing. The model is useful for designing nanotube sensor systems. A biomimetic artificial neuron was developed by extending the length of the sensor. The neuron is a long continuous strain sensor that has a low cost, is simple to install and is lightweight. The neuron has a low bandwidth and adequate strain sensitivity. The neuron sensor is particularly useful for detecting large strains and cracking, and can reduce the number of channels of data acquisition needed for the health monitoring of large structures.

Soft Actuators for Small-Scale Robotics.

Abstract: This review comprises a detailed survey of ongoing methodologies for soft actuators, highlighting approaches suitable for nanometer- to centimeter-scale robotic applications. Soft robots present a special design challenge in that their actuation and sensing mechanisms are often highly integrated with the robot body and overall functionality. When less than a centimeter, they belong to an even more special subcategory of robots or devices, in that they often lack on-board power, sensing, computation, and control. Soft, active materials are particularly well suited for this task, with a wide range of stimulants and a number of impressive examples, demonstrating large deformations, high motion complexities, and varied multifunctionality. Recent research includes both the development of new materials and composites, as well as novel implementations leveraging the unique properties of soft materials.