• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.253-254
• /
• 2022

In this study, catechol-functionalized chitosan (Cat-Chit), a well-known bioinspired polymer that imitates the basic structures and functions of living organisms and biological materials in nature, was synthesized and combined with cement mortar in various proportions. The compressive strength, tensile strength, drying shrinkage, accelerated carbonation depth, and chloride-ion penetrability of these mixes were then evaluated. In the ultraviolet-visible spectra, a maximum absorption peak appeared at 280 nm, corresponding to catechol conjugation. The sample containing 7.5% Cat-Chit polymer in water (CPW) exhibited the highest compressive strength, and its 28-day compressive strength was ~20.2% higher than that of a control sample with no added polymer. The tensile strength of the samples containing 5% or more CPW was ~2.3-11.5% higher than that of the control sample. Additionally, all the Cat-Chit polymer mixtures exhibited lower carbonation depths than compared to the control sample. The total charge passing through the samples decreased as the amount of CPW increased. Thus, incorporating this polymer effectively improved the mechanical properties, carbonation resistance, and chloride-ion penetration resistance of cement mortar.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.380-381
• /
• 2012

Bioinspired sea urchin-like structures were fabricated on silicon by inductively coupled plasma (ICP) etching using lens-like shape hexagonally patterned photoresist (PR) patterns and subsequent metal-assisted chemical etching (MaCE) [1]. The lens-like shape PR patterns with a diameter of 2 ${\mu}m$ were formed by conventional lithography method followed by thermal reflow process of PR patterns on a hotplate at $170^{\circ}C$ for 40 s. ICP etching process was carried out in an SF6 plasma ambient using an optimum etching conditions such as radio-frequency power of 50 W, ICP power of 25 W, SF6 flow rate of 30 sccm, process pressure of 10 mTorr, and etching time of 150 s in order to produce micron structure with tapered etch profile. 15 nm thick Ag film was evaporated on the samples using e-beam evaporator with a deposition rate of 0.05 nm/s. To form Ag nanoparticles (NPs), the samples were thermally treated (thermally dewetted) in a rapid thermal annealing system at $500^{\circ}C$ for 1 min in a nitrogen environment. The Ag thickness and thermal dewetting conditions were carefully chosen to obtain isolated Ag NPs. To fabricate needle-like nanostructures on both the micron structure (i.e., sea urchin-like structures) and flat surface of silicon, MaCE process, which is based on the strong catalytic activity of metal, was performed in a chemical etchant (HNO3: HF: H2O = 4: 1: 20) using Ag NPs at room temperature for 1 min. Finally, the residual Ag NPs were removed by immersion in a HNO3 solution. The fabricated structures after each process steps are shown in figure 1. It is well-known that the hierarchical micro- and nanostructures have efficient light harvesting properties [2-3]. Therefore, this fabrication technique for production of sea urchin-like structures is applicable to improve the performance of light harvesting devices.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.6 no.4
• /
• pp.205-212
• /
• 2001

One of the important characteristics of biological systems os their ability to change im-portant properties in response to small environmental signals. The molecular mechanisms that biological molecules utilize to sense and respond provide interesting models for the development of "smart" polymeric biomaterials with biomimetic properties. An important example of this is the protein coat of viruses, which contains peptide units that facilitate the trafficking of the virus into the cell via endocytosis, then out of the endosome into the cytoplasm, and from there into the nucleus, We have designed a family of synthetic polymers whose compositions have been de-signed to mimic specific peptides on viral coats that facilitate endosomal escape. Our biomimetic polymers are responsive to the lowered pH whinin endosomes, leading to distruption of the en-dosomal membrane and release of important biomolecular druges such as DNA, RNA, peptides and proteins to the cytoplasm before they are trafficked to lysosomes and degraded by lysosomal en-zymes. In this article, we review our work on the design, synthesis and action of such smart, pH-sensitive polymers.

• Journal of the Korea Convergence Society
• /
• v.9 no.9
• /
• pp.299-307
• /
• 2018

This paper tried to produce the abstract nail designs using the colors expressed in the works by the artist Chun Kyung-ja. The approach in this paper aimed to prepare the basis for realizing the creative idea on the nail design and to help to expand the expression field of nail design. The works expressing the artistic features of the artist Chun Kyung-ja well were selected for the empirical research and color data was analyzed using NCS(Natural Color System). Finally, 5 kinds of representative works on the works by the artist Chun Kyung-ja were selected and applied to nail designs for creating nail designs as well as application of colors. In conclusion, the nail design of this research is convergence of nail design and the modern Korean painting. Based on such convergence, this paper expressed the nail design by recreating the of beauty design by various viewpoints.

• Transactions of the KSME C: Technology and Education
• /
• v.1 no.2
• /
• pp.211-219
• /
• 2013

Even though global warming and humid climate have resulted in an increase of use of dehumidifiers, they are not becoming more common because of high energy consumption. Furthermore, conventional dehumidifier technology finally reaches the limit to increase energy efficiency of water collection. As an alternative, nature-inspired technology may lead to a major breakthrough in the dehumidification performance. In order to improve the efficiency of dehumidifiers, we first analyze the energy consumption of commercial dehumidifiers and then study bioinspired water collection methods adopted by Namib beetles and grass.

• Journal of the Korean Magnetics Society
• /
• v.18 no.4
• /
• pp.154-158
• /
• 2008

Magnetite($Fe_3O_4$) is currently one of key materials for applications in magnetic storage and many bioinspired applications because bulk $Fe_3O_4$ has a high Curie temperature($Tc={\sim}850K$) and nearly full spin polarization at room temperature(RT). In this work, $Fe_3O_4$ nanoparticles with different sizes of 12 to 15 nm were prepared in a well-controlled manner by a nonhydrolytic synthetic method. Here, we report the significant intergrain magneto-resistance(MR) of ${\sim}2%$ at RT in $Fe_3O_4$ nanoparticle pellets. The tunneling conductance was also investigated based on the Brinkman model, as well. Our results show clearly that the surface or interfacial property of the particles plays a crucial role in the MR effect.

• Journal of the Microelectronics and Packaging Society
• /
• v.30 no.4
• /
• pp.1-7
• /
• 2023

The ability of 3D/4D printing technology to create arbitrary 3D structures provides a greater degree of freedom in the design of printed structures. This capability has influenced the field of electronics and biomedical applications by enabling the trends of device miniaturization, customization, and personalization. Here, the current state-of-the-art knowledge of 3D printed electronics and biomedical applications with the unique and unusual properties enabled by 3D/4D printing is reviewed. Specifically, the review encompasses emerging areas involving recyclable and degradable electronics, metamaterial-based pressure sensor, fully printed portable photodetector, biocompatible and high-strength teeth, bioinspired microneedle, and transformable tube array for 3D cell culture and histology.