• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.285-286
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• 2005

Organic photovoltaic properties were studied in ZnPc/$C_{60}$ heterojunction structure by varying the organic layer thicknesses and exiton blocking layer(EBL). Current density-voltage characteristics of organic photovoltaic cells were measured using Keithley 236 source-measure unit, a 500W xenon lamp (ORIEL 66021) for a light source and Agilent 4294A impedance analyzer in the range of 40 Hz $\sim$ 1 MHz. From the analyses of current-voltage characteristics such as short-circuit current density, open-circuit voltage and power conversion efficiency, optimum thickness of the organic layer were obtained and frequency response such as electrical conductance.

• Journal of Powder Materials
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• v.20 no.6
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• pp.439-444
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• 2013

Fe foam with above 90% porosity and 2 millimeter pore size was successfully fabricated by a slurry coating process. In this study, the binder contents were controlled to produce the Fe foam with different pore size, strut thickness and porosity. Firstly, the slurry was prepared by uniform mixing with Fe powders, distilled water and polyvinyl alcohol(PVA) as initial materials. After slurry coating on the polyurethane(PU) foam the sample was dried at $80^{\circ}C$. The PVA and PU foams were then removed by heating at $700^{\circ}C$ for 3 hours. The debinded samples were subsequently sintered at $1250^{\circ}C$ with holding time of 3 hours under hydrogen atmosphere. The three dimensional geometries of the obtained Fe foams with open cell structure were investigated using X-ray micro CT(computed tomography) as well as the pore morphology, size and phase.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1416-1421
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• 2006

We identified a gene encoding the N-acetylmuramoyl L-alanine amidase (amiB) of Vibrio anguillarum, which catalyzes the degradation of peptidoglycan in bacteria. The entire open reading frame (ORF) of the amiB gene was composed of 1,722 nucleotides and 573 amino acids. The deduced amino acid sequence of AmiB showed a modular structure with two main domains; an N-terminal region exhibiting an Ami domain and three highly conserved, continuously repeating LysM domains in the C-terminal portion. An amiB mutant was constructed by homologous recombination to study the biochemical function of the AmiB protein in V. anguillarum. Transmission electron microscopy (TEM) revealed morphological differences, and that the mutant strain formed trimeric and tetrameric unseparated cells, suggesting that this enzyme is involved in the separation of daughter cells after cell division. Furthermore, inactivation of the amiB gene resulted in a marked increase of sensitivity to oxidative stress and organic acids.

• Polymer(Korea)
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• v.37 no.4
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• pp.478-485
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• 2013

In this study, hydrogels with fast swelling and high absorbent properties were prepared using biopolymers approved as a food additive and their swelling properties were characterized. To improve the swelling properties of conventional hydrogels, we formed gas bubbles using a foaming agent in the process of preparing hydrogels and characterized in terms of equilibrium swelling ratio, swelling kinetics and cytotoxicity. In particular, alginate hydrogels observed by a digital microscope have an open-pore channels structure with the sizes of hundreds micrometers. Also, the cell viability of all hydrogels were found to be much higher than that of poly(acrylic acid).

• Current Photovoltaic Research
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• v.7 no.3
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• pp.61-64
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• 2019

In this study, we investigate organic-inorganic hybrid solar cells with a very simple three-layer structure (Al/n-Si/PEDOT:PSS). The performance of hybrid solar cells is optimized by controlling the sheet resistance and optical transmittance of the PEDOT:PSS layers. As the thickness of the PEDOT:PSS layer decreases, the optical absorption of the n-Si increases, which greatly improves the short-circuit current density ($J_{SC}$) of devices, but the increase in sheet resistance leads to a decrease in the open-circuit voltage ($V_{OC}$) and the fill factor (FF). The solar cell with the 180-nm thick PEDOT:PSS layer shows a highest efficiency of 8.45% ($V_{OC}$: 0.435 V, $J_{SC}$: $33.7mA/cm^2$, FF: 57.5%). Considering these results, it is expected that the optimizing process for the sheet resistance and transmittance of the PEDOT:PSS layer is essential for producing high-efficiency organic-inorganic hybrid solar cells and will serve as an important basis for achieving low-cost, high-efficiency solar cells.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.421-426
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• 2024

Ru dye (Z-907) is a crucial photosensitizing material in dye-sensitized solar cells (DSSCs). To enhance the utilization of Ru dye's photosensitizing properties in bulk heterojunction solar cells, a method was developed to synthesize phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles that are chemically linked to Ru dye. PCBM contains a methoxy (-OCH₃) group, whereas Ru dye incorporates a carboxyl group (-COOH) within its molecular structure. By exploiting these complementary functional groups, a successful bond between Ru dye and PCBM was established through an anhydride functional group. The coupling of PCBM with Ru dye results in a modification of the energy levels, yielding lower LUMO (3.8 eV) and HOMO (6.1 eV) levels, compared with the LUMO (3.0 eV) and HOMO (5.2 eV) levels of Ru dye alone. This configuration potentially facilitates efficient electron transfer from Ru dye to PCBM, alongside promoting hole transfer from Ru dye to the conducting polymer. Consequently, the bulk heterojunction solar cells incorporating this Ru dye-PCBM configuration demonstrate superior performance, with an open circuit voltage (V_oc) of 0.62 V, short circuit current (J_sc) of 0.63 mA cm^-2, fill factor (FF) of 65.6%, and a photovoltaic conversion efficiency (η) of 0.25%.

• Journal of Applied Biological Chemistry
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• v.62 no.3
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• pp.239-246
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• 2019

In this study, an evaluation of the anti-inflammatory effect of ferulic acid isolated from Tetragonia tetragonioides in lipopolysaccharide (LPS) simulated RAW 264.7 cells was made. The chemical structure of the active compound was elucidated by $^1H$-NMR, $^{13}C$-NMR, and FAB-MS, and was confirmed to be ferulic acid. Ferulic acid was purified via open column chromatography with Sephadex LH-20 and MCI gel CHP-20. To test the anti-inflammatory effect of ferulic acid, LPS-stimulated RAW 264.7 cells were treated in subsequent experiments with different concentrations of ferulic acid (5, 10, and $25{\mu}g/mL$) and the levels of inflammatory cytokines and enzymes were also measured by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Cell viability was above 95% at acid concentrations ranging from $5-25{\mu}g/mL$. The results showed that 30% of the production of nitric oxide and 66% of prostaglandin $E_2$ were inhibited by $25{\mu}g/mL$ of ferulic acid, it also inhibited the protein expression of both inducible nitric oxide synthase and cyclooxygenase-2 by 70%. Additionally, it inhibited the production of the pro-inflammatory cytokines, tumor necrosis factor-${\alpha}$, interleukin-6, and interleukin-$1{\beta}$ by 40, 75, and 77%, respectively. According to these results, the anti-inflammatory activity of ferulic acid was demonstrated via his implication in the inhibition of the expression and secretion of inflammatory substances in LPS-stimulated RAW 264.7 cells. Therefore, we concluded that ferulic acid can be used as a functional additive having anti-inflammatory activity.

• International Journal of Advanced Culture Technology
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• v.10 no.1
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• pp.274-283
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• 2022

Korea is facing a number difficulties arising from rising housing prices. As 'housing' takes the lion's share in personal assets, many difficulties are expected to arise from fluctuating housing prices. The purpose of this study is creating housing price prediction model to prevent such risks and induce reasonable real estate purchases. This study made many attempts for understanding real estate instability and creating appropriate housing price prediction model. This study predicted and validated housing prices by using the LSTM technique - a type of Artificial Intelligence deep learning technology. LSTM is a network in which cell state and hidden state are recursively calculated in a structure which added cell state, which is conveyor belt role, to the existing RNN's hidden state. The real sale prices of apartments in autonomous districts ranging from January 2006 to December 2019 were collected through the Ministry of Land, Infrastructure, and Transport's real sale price open system and basic apartment and commercial district information were collected through the Public Data Portal and the Seoul Metropolitan City Data. The collected real sale price data were scaled based on monthly average sale price and a total of 168 data were organized by preprocessing respective data based on address. In order to predict prices, the LSTM implementation process was conducted by setting training period as 29 months (April 2015 to August 2017), validation period as 13 months (September 2017 to September 2018), and test period as 13 months (December 2018 to December 2019) according to time series data set. As a result of this study for predicting 'prices', there have been the following results. Firstly, this study obtained 76 percent of prediction similarity. We tried to design a prediction model of real estate transaction price with the LSTM Model based on AI and Bigdata. The final prediction model was created by collecting time series data, which identified the fact that 76 percent model can be made. This validated that predicting rate of return through the LSTM method can gain reliability.

• Journal of Life Science
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• v.27 no.4
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• pp.398-407
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• 2017

BTG 1 (B-cell translocation gene 1) gene was first identified as a translocation gene in a case of B-cell chronic lympocytic leukemia. BTG1 is a member of the BTG/TOB family with sharing a conserved N-terminal region, which shows anti-proliferation properties and is able to stimulate cell differentiation. In this study, we identified and characterized the pacific oyster Crassostrea gigas BTG1 (cg-BTG1) gene from the gill cDNA library by an Expressed Sequence Tag (EST) analysis and its nucleotide sequence was determined. The cg-BTG1 gene encodes a predicted protein of 182 amino acids with 57% 56% identities to its zebrafish and human counterparts, and is an intron-less gene, which was confirmed by PCR analysis of genomic DNA. Maximal homologies were shown in conserved Box A and B. The deduced amino acid sequence shares high identity with other BTG1 genes of human, rat, mouse and zebrafish. The phylogenic analysis and sequence comparison of cg-BTG1 with other BTG1 were found to be closely related to the BTG1 gene structure. In addition, the predicted promoter region and the different transcription-factor binding site like an activator protein-1 (AP-1) response element involved in negative regulation and serum response element (SRE) were able to be identified by the genomic DNA walking experiment. The quantitative real-time PCR analysis showed that the mRNA of cg-BTG1 gene was expressed in gill, heart, digestive gland, intestine, stomach and mantle. The cg-BTG1 gene was expressed mainly in heart and mantle.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1356-1364
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• 2014

A new conjugated copolymer, poly{4,8-bis(triisopropylsilylethynyl)benzo[1,2-b:4,5-b']dithiophene-alt-4,7- bis(5-thiophen-2-yl)-5,6-difluoro-2-(heptadecan-9-yl)-2H-benzo[d][1,2,3]triazole} (PTIPSBDT-DFDTBTz), is synthesized by Stille coupling polycondensation. The synthesized polymer has a band gap energy of 1.9 eV, and it absorbs light in the range 300-610 nm. The hole mobility of a solution-processed organic thin-film transistor fabricated using PTIPSBDT-DFDTBTz is $3.8{\times}10^{-3}cm^2V^{-1}s^{-1}$. Bulk heterojunction photovoltaic cells are fabricated, with a conventional device structure of ITO/PEDOT:PSS/polymer:$PC_{71}BM$/Ca/Al ($PC_{71}BM$ = [6,6]-phenyl-$C_{71}$-butyric acid methyl ester); the device shows a power conversion efficiency (PCE) of 2.86% with an open-circuit voltage ($V_{oc}$) of 0.85 V, a short-circuit current density ($J_{sc}$) of 7.60 mA $cm^{-2}$, and a fill factor (FF) of 0.44. Inverted photovoltaic cells with the structure ITO/ethoxylated polyethlyenimine/ polymer:$PC_{71}BM/MoO_3$/Ag are also fabricated; the device exhibits a maximum PCE of 2.92%, with a $V_{oc}$ of 0.89 V, a $J_{sc}$ of 6.81 mA $cm^{-2}$, and an FF of 0.48.