• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.394-395
• /
• 2007

In order to make full color cholesteric displays, color filter-less R, G, B sub-pixel structured cholesteric LC cells have been studied. To make R, G, B colors, UV induced pitch variant chiral dopant was added to cholesteric LC mixtures. The concentration of the photo-sensitive chiral dopant was adjusted so that the initial state showed blue color and the color was changed from blue to green and red with increase of UV irradiation to the cholesteric cells. To prevent the mixing of R, G, B reflective sub-pixel liquid crystals, separation walls were formed using negative photo resister in boundary area between sub-pixels. Through the optimization of the material concentrations and UV irradiation condition, vivid R, G, B colors were achieved.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.272-272
• /
• 2013

The attractive features of photosynthetic reaction center proteins for energy application make them useful in solar energy conversion to hydrogen fuel or electrical energy. Almost unity charge separation quantum yield and its rapid speed of ~1ns, absorbance region in visible light (480~740 nm) and high proportion of photosynthetically active solar energy of 48.5% allowed photosystem1 to exploited as a bio-material for photo-energy devices. Directionality of photosystem1 in electron transfer can solve main problem in two-step water splitting process where back reaction deteriorates the overall efficiency. In the study, photosystem1 was extracted from spinach and the photo-induced excited electron in the reaction center was utilized in various field of light energy application. First, hydrogen evolving system realized by photodeposition of platinum at the end of the electron transfer chain, with combining specific semiconductor to oxidize water in the first step of Z-scheme. The evaluation by gas-chromatography demonstrated hydrogen evolution through the system. For the further application of photoelectrical material on electrode, photosystem1 have been controlled by copper ion, which is expected to assemble photosystem in specific orientation followed by maximized photoelectrical ability of film. The research proposed concrete methods for combining natural protein and artificial materials in one system and suggested possibility of designing interface between biological and inorganic materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.37 no.2
• /
• pp.202-207
• /
• 2024

This study examines a manufacturing process for the photoelectrode material of dye-sensitized solar cell (DSSC) intending to increase efficiency through the surface plasmon resonance phenomenon of nanoparticles with a composite structure made of Ag and TiO₂. This invention involves the use of Ag and TiO₂ nanoparticles in the solar cell. These nanoparticles cause surface plasmon resonance, which amplifies and scatters incident solar energy, enhancing the dye's rate of light absorption. It also makes it possible to absorb energy in wavelength ranges that were previously difficult to do, which increases efficiency. Centrifugal separation and heat synthesis are used to create the composite metal structures, and certain combinations are used to decide the particle morphologies. To increase the efficiency of organic solar cells and DSSC, the Ag/TiO₂ composite structure is therefore quite likely to be used.

• Tunnel and Underground Space
• /
• v.19 no.6
• /
• pp.534-544
• /
• 2009

The collapse of the underground cavity can cause the abrupt local subsidence of the ground surface. It can be hazardous to the stability of road and building for human activity. Therefore it is necessary to develop reinforcement methods for the filling of the underground cavity. This study was executed to improve the material quality and systems to fill the calcium-aluminate mineral $(C_{12}A_7)$ environmentally, and minimize the loss of filling materials for the steep underground cavity. Filling material which was developed in this study is composed of rapid hardening material and additives. The developed material had rapid hardening and non-separation ability in the water cavity condition, so it made the effective underground dam in the cavity with prevention of material loss when it was poured in the water cavity. Results of heavy metal leaching test for environmental assessment showed that it was environmentally suiTable material for the filling in the mine cavity.

• Journal of the Korean Geosynthetics Society
• /
• v.21 no.4
• /
• pp.101-109
• /
• 2022

This study describes the results of model experiment to analyze the effect of backfill material types on the behavior of underground facility. In the model experiment, backfill materials around the existing underground facility were applied with soil (Jumunjin standard sand) and CLSM. The displacement of underground facility was analyzed for each excavation stage considering the separation distance between the excavation surface and the backfill area based on the experimental results. When soil was applied as a backfill material, the soil on the back of the excavation surface collapsed by excavation and formed an angle of repose, and the process of slope stability was repeated at each excavation stage. In addition, the displacement of underground facility began to occur in the excavation stage that the failure line of soil passes the installation location of the underground facility. When CLSM was applied as a backfill material, there was almost no horizontal and vertical displacement of the ground regardless of the separation distance from the excavation surface even when excavation proceeded to the backfill depth. Therefore, this result showed that it can have a resistance effect against the lateral earth pressure generated and the collapse of the original ground by adjacent excavation, if a backfill material with high stiffness such as CLSM is applied.

• Journal of the Korean Society of Radiology
• /
• v.17 no.4
• /
• pp.523-529
• /
• 2023

In order to achieve excellent spatial resolution, very small scintillation pixels are used in detectors of positron emission tomography for small animals. However, by using these very small scintillation pixels, scintillation pixels at the edge of the array may overlap in a flood image. To solve this problem, a light guide capable of changing the distribution of light was used. Depending on the material of the light guide, the light spreading tendency is different, and accordingly, the presence or absence of overlapping is different depending on the material of the light guide used. In this study, instead of the conventional glass light guide, a detector using the same material as the scintillation pixel was designed. A scintillator light guide has a higher refractive index than a glass light guide, so the light spread is different. Flood images were acquired to evaluate the degree of separation of the scintillation pixels at the edge of the detector using the two light guides. The degree of separation was evaluated by calculating the distance between the center and the spatial resolution of the image of two scintillation pixels at the edge of the obtained flood image. As a result, when the scintillator light guide was used, better spatial resolution was shown, and the distance between centers of scintillation pixels was wider. When a detector is constructed using a scintillator light guide instead of a conventional glass light guide, it is possible to use a smaller scintillation pixel, thereby securing better spatial resolution.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.4
• /
• pp.17-24
• /
• 2021

The development of a new sorbent for carbon dioxide depends on several factors, such as fast adsorption/absorption velocity, hydrophobicity, and lower regeneration temperature than commercial sorbent. In this study, aminosilane grafted activated carbon was synthesized to capture CO2. Methyltrimethoxysilane (MTMS) and 3-aminopropyl-triethoxysilane (APTES) were used as the grafting precursor of the amine functional group. The APTES grafting activated carbon showed higher sorption property than MTMS used one. The characteristics of the separation mechanism of carbon dioxide were examined by measuring the adsorption capacity according to temperature and carbon dioxide partial pressure. The absorption capacity of carbon dioxide was similar to amine grafting activated carbon and activated carbon at 25℃, but amine-grafted activated carbon was higher at 75℃. The amine functional group-grafted activated carbon showed higher absorption capacity than activated carbon with a 1% carbon dioxide partial pressure. Aminosilane grafting of activated carbon was chemically absorbed but also showed the characteristics of physical adsorption. The reforming activated carbon with an amine functional group grafted solid absorption/adsorption sorbent would significantly impact the material engineering industry and carbon dioxide adsorption process. The functionalized sorbent is a high-performance composite material. The developed sorbent may have applications in other industrial processes of absorption/adsorption and separation.

• Applied Chemistry for Engineering
• /
• v.35 no.5
• /
• pp.468-472
• /
• 2024

This study experimentally examined the separation performance of indole (IN) contained in crude methyl naphthalene oil (CMNO) by methanol extraction and then compared these results with formamide extraction. CMNO containing about 4.36% IN, which is attracting attention as an intermediate raw material such as medicine, essential amino acids, and perfumes, was used as a raw material, and methanol aqueous solution was used as a solvent, respectively. The increase in the initial volume fraction of water in the solvent (y_w,0) sharply decreased the distribution coefficient (m_IN) and yield (Y_IN) of IN, but conversely increased the selectivity of IN in reference to 2-methylnaphthalene (2MNA). An increase in the initial volume ratio of solvent to feed (E₀/R₀) increased m_IN, Y_IN, and 𝛽_IN,2MNA. In the range of 0.1 ≤ y_w,0 ≤ 0.3, m_IN and Y_IN of methanol extraction were approximately 1.9~5.9 times and 1.8~3.6 times greater than those of formamide extraction, respectively, whereas 𝛽_IN,2MNA of formamide extraction were 4.6~8.2 times greater than those of methanol extraction.

• Journal of the Korean Chemical Society
• /
• v.63 no.6
• /
• pp.440-445
• /
• 2019

It has developed a method that can recover efficiently the reproducible resources from the vehicle waste lithium second battery module. Module cell consists of copper thin film, aluminum thin film and diaphragm made with polymer between these thin films. Cell was disassembled completely without any damage in glove box and through several steps. Preferentially, cathode active material was separated from aluminum thin film at heat treatment of 400 ℃. The retrieved cathode active material was then obtained as high purity after calcining at 800 ℃ to remove residual carbon. Based on this study, it was found that rare metals such as Co, Ni, Mn and Li made up of cathode active material could recover above 80% from aluminum thin film.

• The Journal of Korean Academy of Prosthodontics
• /
• v.34 no.2
• /
• pp.290-298
• /
• 1996

The effects of impression tray disinfection procedures on the bond strength of impression-material adhesive to two of types resin trays were evaluated with a tensile test. Autopolyme-rizing acrylic resin was formed into 1x1x1 cm cubes. A hook was attached to each cube with autopolymerizing acrylic resin. Perforated trays were fabricated with stops to maintain an even 3 cm of impression material over the resin block. Hook on the opposite side of the perforated tray permitted attachment of the metal plate to a mechanical testing machine. Before adhesive was applied, one third of the resin specimens were immersed in a 5% sodium hypochlorite solution : one third in a 2% glutaradehyde solution, and one third were kept in the "as fabricated" condition. Three products(Perfect ups, Exafine, and Exp-ress) of polyvynil siloxane impression material-adhesive system were evaluated. The resin-impression material-metal plate couples were attached to a mechanical testing machine and tensile forces were applied at a separation rate of 10 centimeters per second. The results were as follows; 1. Both disinfectant and adhesive had effects on bond strength values, but adhesive had more effect than disinfectant(p<0.01). However, there was no interaction between dinin-fectant and adhesive(p>0.01). 2. Mean bond strength values for the Perfect materials were about 85% less than that of the Exafine or the Express materials. However, there was no stastically significant difference between the mean bond strength values of the Exafine materials and the Express materials(p>0.05). 3. The use of disinfectants produced significant reduction in bond strength values(p<0.05). But there was no stastically significant difference between the mean bond strength values of the groups treated with disinfectants(p>0.05).