• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.985-986
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• 2011

• Composites Research
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• v.32 no.5
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• pp.237-242
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• 2019

In this research, a capacitive pressure sensor (Piezocapacitive Sensor) was fabricated using carbon black powder containing poly-dimethylsiloxane (PDMS) with micro-grid patterned surface. To investigate the effect of carbon black powder and micro-grid pattern on the sensor's performance, various sensors were fabricated with different carbon black powder concentration and grid pattern density. The performances of the developed sensors were compared in terms of operating range and sensitivity.

• Composites Research
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• v.27 no.6
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• pp.242-247
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• 2014

The fabrication of flexible electrodes coated on the surface of a dielectric elastomer film, which is a type of electroactive polymer (EAP), was carried out. Controlled amounts of Xylitol powder were added (10, 30, 50 and 70 wt%) to the commercial conductive polymer (PEDOT:PSS) to enhance resilience of the electrode. To check resilience of the fabricated composite electrodes, tensile tests were carried out using silicone films coated with the polymer electrodes. From the test results, it was found that 70 wt% Xylitol containing conductive polymer had excellent elongation and high failure strains. Furthermore, surface of the silicone film was uniformly polished with various abrading papers to enhance the wettability of the conductive polymers on the surface of the silicone film. It was found that the silicone film polished with #120 abrading paper had the best wettability and guaranteed excellent bonding behavior.

• Composites Research
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• v.32 no.5
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• pp.211-215
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• 2019

The cell culture process under in vitro condition is much different from the actual human body environment. Therefore, in order to precisely simulate the human body environment, a dynamic cell culture device capable of delivering mechanical stimulation to cells is essential. However, conventional dynamic cell culture devices require relatively complicated devices such as tubes, pumps, and motors, and the mechanical stimuli delivered is also simple. In this study, an electro-active polymer actuator as a driving component is introduced to design simply driven dynamic cell culture device without complicated components. The device is capable of delivering relatively complex mechanical stimuli to the cells.

• Computational Structural Engineering
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• v.9 no.1
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• pp.101-113
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• 1996

In this paper, the finite element formulation for the thermal analysis of quasi-static, uncoupled, homogeneous, isotropic and linear viscoelastic problems is presented based on the principle of virtual work. The viscoelastic material is assumed to be thermorheologically simple, which is well known material property in a large class of high polymers. The variational formulation and the finite element equation in matrix from are derived. Effective generation and storage of the hereditary stiffness matrices are given in detail especially for the case of the steady state temperature distribution T=T(x). Some numerical examples are given and compared with published results to show the versatility of the derived finite element formulations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.334-337
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• 2003

In this paper. we introduce a novel actuation method based on dielectric elastomer. Along with basic principles of actuation using dielectric elastomer a new design of actuator is discussed. The proposed design has advantageous features in reduction in size, speed of response, ease and ruggedness of operation. Using the actuator. a three-degree-of-freedom actuator module is developed, which can provide up-down. and two rotational degree-of-freedom motion. In the application of the proposed actuation method, a micro-robot mimicking the motion of an inchworm is developed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.2
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• pp.235-241
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• 2001

A crack with electrically conducting surfaces in a linear electrostrictive ceramic subjected to uniform electric fields is analyzed. Complete forms of electric fields and elastic fields for the crack are derived by using the complex function theory. The linear electromechanical theory predicts overlapping of the traction free crack surfaces. It is shown that the surfaces of the crack are contact near the crack tip. The contact zone size obtained on the basis of the linear dielectric theory for the conducting crack does not depend on the electric fields and depends on only the original crack and the material property for the linear electrostrictive ceramic.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.56-64
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• 2002

In this work, a smart skin of multi-layer structure is designed and manufactured. Through the compression test, the characteristic of smart skin behavior was examined. We have predicted stress of each layer and the first failed layer of the smart skin structure by using MSC/NASTRAN. The finite element model was verified by comparing measured data from the compression test and result from the geometrically linear/non-linear analysis. The finite element model was used for obtaining design data from the parametric study. It was confirmed that shear moduli of honeycomb core affect the buckling load of smart skin where shear deformation was considerable.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.134-140
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• 1995

SAW properties of SiNx/ZnO bilayer thin film structure were analyzed. ZnO thin films were deposited by rf magnetron sputter using O2 gas as an oxidizer. Structure of ZnO thin films was affected by Ar/O2 ratio. At the gas ratio of Ar/O2=67/33, the standard deviation of X-ray rocking curve of (002) preferred ZnO thin film was 2.17 degree. This value is sufficient to use ZnO thin films as an acoustic element. SAW velocity of glass/SiNx(7000Å)/Al/ZnO(5μm) structure was max. 2.2% faster than that of ZnO/glass.

• Clinical and Experimental Pediatrics
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• v.50 no.3
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• pp.306-310
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• 2007

Restrictive dermopathy is a rare autosomal recessive disorder in which rigidity or tautness of the skin from the second trimester causes a fetal akinesia deformation sequence (FADS) and early death. Characteristic features include taut skin with prominent subcutaneous vessels, widely open fontanelles and cranial sutures, distinctive facies, flexion contractures, pulmonary hypoplasia, sparse eyelashes and and eyebrows, thin dysplastic clavicles. The histologic abnormalities of the skin are located in a thin dermis, consisting of compactly arranged collagen fibers, scanty elastic fiber. The dermoepidermal junction is flat, and epidermal appendages are absent, miniaturized or immature. The presence of adipose tissue may be increased. We report on the first Korean case of restrictive dermopathy with typical clinical features and histological findings.