• Applied Chemistry for Engineering
• /
• v.16 no.2
• /
• pp.257-261
• /
• 2005

The microbial cellulose is in a form of three dimensional net structures that consists of 20~50 nm fibrils. It possesses high crystallinity and orientation. It is difficult to synthesize large amount of fibrous carbon nanomaterials by the carbonization process using raw materials such as polyacrylonitrile (PAN), regenerated cellulose (Rayon) and pitch. However, it seems possible thru the application of microbial cellulose as raw material. The application of such cellulose can be further extended to the synthesis of highly oriented graphite fiber. Out of three different cellulose-producing strains, G. xylinus ATCC11142 was chosen as it has the highest productivity (0.066 g dried cellulose/15 mL medium). Tar is often produced during the carbonization of cellulose that limits the formation fibrous structure of the carbonized sample. In order to solve such a problem, pre-studied purification methods of carbon nanotube such as liquid phase oxidation, gas phase oxidation and filtration associated with ultrasonication were applied at the carbonized cellulose. In that case. only by filtration associated with ultrasonication, improved the formation of fiber structure of the carbonized cellulose.

• Korean Chemical Engineering Research
• /
• v.62 no.1
• /
• pp.105-111
• /
• 2024

The SLA (Stereolithography Apparatus) method is a type of 3D printing technique predicated on the transformation of liquid photocurable resin into a solid form through UV laser exposure, and its application is increasing in various fields. In this study, we conducted research to enhance the hydrophobicity and transparency of SLA 3D printing surfaces for microfluidic system production. The enhancement of surface hydrophobicity in SLA outputs was attainable through the application of hydrophobic coating methods, but the coating durability under different conditions varied depending on the type of hydrophobic coating. Additionally, to simultaneously achieve the required transparency and hydrophobic properties for the fabrication of microfluidic systems, we applied hydrophobic coatings to the proposed transparency enhancement method from prior research and compared the changes in contact angles. Teflon coating was proposed as a suitable hydrophobic coating method for the fabrication of microfluidic systems, given its excellent transparency and high coating durability in various environmental conditions, in comparison to titanium dioxide coating. Finally, we produced an Electrophoresis of Charged Droplet (ECD) chip, one of the digital microfluidics systems, using SLA 3D printing with the proposed Teflon coating method (Fluoropel 800). Droplet manipulation was successfully demonstrated with the fabricated chip, confirming the potential application of SLA 3D printing technology in the production of microfluidic systems.

• Journal of Korean Classical Literature and Education
• /
• no.33
• /
• pp.121-152
• /
• 2016

The purpose of this study is to illustrate the history of the Cheonsu-Temple天壽寺 and to describe the echo verse poem trend with regard to 'Waiting'待人 and why it is beautiful. The Cheonsu-Temple was located in the outskirts of Gaesung開城, the capital city during the Corea高麗 Dynasty. However, the temple was destroyed when the dynasty collapsed. Cheonsu-Station天壽院 was built amidst the temple ruins, as the temple was an important traffic point. The Cheonsu-Pavilion天水亭 was built in 1476 by Yi-Ye李芮 in the station's neighborhood. The station and the pavilion were completely ruined during the 17th century. Many poets visited the Cheonsu-Temple and composed poems in the latter part of the Corea Dynasty. 'Waiting'待人, written by Choi-Sarip崔斯立, -is the most famous work. Following this work, many poets composed echo verse poems 'Waiting' work that represented the anxiety of waiting for an old friend in front of the Cheonsu-Temple. The following is a highlighted verse: So many people who look like the old friend come to me, but it turned out no one was the man. This work is very picturesque. Over twenty echo verse poems 'Waiting' are categorized in three periods. They compared the "present" to the past by using the Zhenglingwei丁令威 origin from the former Joseon朝鮮 period. In the middle of Joseon period, Jungjong中宗 visited Cheonsu-Station and composed an echo verse poem 'Waiting'. The official literaries also composed poems there. In their works, they presented the collapse of the Corea Dynasty as inevitable and the construction of Joseon Dynasty as something reasonable. Cheonsu-Station was ruined in 17th century, followed after by the ruin of the Cheonsu-Pavilion. It appears that the echo verse poems to 'Waiting' in the latter Joseon period represented the ruin of the Cheonsu-Temple, the Cheonsu-Station, and the Cheonsu-Pavilion.