• Korean Journal of Materials Research
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• v.30 no.11
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• pp.601-608
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• 2020

In this work, Ag₃PO₄/In₂S₃ nanocomposites with low loading of In₂S₃ (5-15 wt %) are fabricated by two step chemical precipitation approach. The microstructure, composition and improved photoelectrochemical properties of the as-prepared composites are studied by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photocurrent density, EIS and amperometric i-t curve analysis. It is found that most of In₂S₃ nanoparticles are deposited on the surfaces of Ag₃PO₄. The as-prepared Ag₃PO₄/In₂S₃ composite (10 wt%) is selected and investigated by SEM and TEM, which exhibits special morphology consisting of lager size substrate (Ag₃PO₄), particles and some nanosheets (In₂S₃). The introduction of In₂S₃ is effective at improving the charge separation and transfer efficiency of Ag₃PO₄/In₂S₃, resulting in an enhancement of photoelectric behavior. The origin of the enhanced photoelectrochemical activity of the In₂S₃-modified Ag₃PO₄ may be due to the improved charge separation, photocurrent stability and oriented electrons transport pathways in environment and energy applications.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.1
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• pp.132-138
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• 2015

Trees, cultivated in containers, are appropriate in soil deformation such as road sites with cutting and filling. This study tested the effectiveness of trees produced in containers for early rootage in street tree transplantation. For the study, Korean Mountain Ashes(Sorbus alnifolia) were used for experimental groups. The groups were categorized into three categories: trees cultivated in containers with mulching treatment(group A), trees cultivated outdoors with mulching treatment (group B), and trees cultivated in containers with weeding treatment(group C). Each group consisted of ten trees of the same size and transplanted to the experimental site. In order to compare each group's rootage, the study was carried out with the chlorophyll fluorescence method by the analysis of photochemical reaction. As a result of the study, group B had the lowest the maximum fluorescence amount(P). The amount of fluorescence increased by OJ transition of the process, and appeared to reduce the photosystem II electron transport efficiency. In photosystem II, electron transfer energy flux through photosystem I(RE1o/RC, RE1o/CS) was also reduced by more than 20% in group B. These results may imply that transplantation of container-cultivated trees with mulching treatment provides the most rapid rootage among the groups. The weeding treatment is also more effective than mulching treatment for rapid rootage of street trees.

• Membrane Journal
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• v.21 no.2
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• pp.193-200
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• 2011

An amphiphilic graft copolymer comprising a poly(vinyl chloride) (PVC) backbone and poly (styrene sulfonic acid) (PSSA) side chains (PVC-g-PSSA) was synthesized via atom transfer radical polymerization (ATRP). Mesoporous titanium dioxide $(TiO_2)$ films with crystalline anatase phase were synthesized via a sol-gel process by templating PVC-g-PSSA graft copolymer. Titanium isopropoxide (TTIP), a $TiO_2$ precursor was selectively incorporated into the hydrophilic PSSA domains of the graft copolymer and grew to form mesoporous $TiO_2$ films, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The performances of dye-sensitized solar cell (DSSC) were systematically investigated by varying spin coating times and the amounts of P25 nanoparticies. The energy conversion efficiency reached up to 2.7% at 100 mW/$cm^2$ upon using quasi-solid-state polymer electrolyte.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.645-652
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• 1997

Electrochemical characteristics and kinetic parameters of copper ion reduction were investigated with a platinum rotating disk electrode (RDE) in a diffusion controlled region. Reduction of Cu(II) in sulfate had one-step two-xelectron process, while the reduction of Cu(II) in chloride solution was involved two one-electron processes. The transfer coefficient of Cu(II) in sulfate solution was lowest, and the transfer coefficient of Cu(I) in halide solutions had the value of nearly one. In chloride solutions, electrodeposition rate of Cu(II) was about one hundred times faster than Cu(I). Diffusion coefficient increased in the order of Cu(II) in chloride solution, Cu(I) in the iodide, bromide, chloride solution, Cu(II) in sulfate solution. The calculated ionic radii and activation energy for diffusion decreased in the same order as above. Morphological study on the copper electrodeposition indicated that the electrode surface became rougher as both concentration and reduction potential increases, and the roughness of the surface was analyzed with UV/VIS spectrophotometer.

• Microbiology and Biotechnology Letters
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• v.39 no.4
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• pp.382-386
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• 2011

Microbial fuel cells (MFC), devices that use bacteria as a catalyst to generate electricity, can utilize a variety of organic wastes as electron donors. The current generated may differ depending on the organic matter concentrations used, when other conditions, such as oxidant supply, proton transfer, internal resistance and so on, are not limiting factors. In these studies, a single-cathode type MFC (SCMFC) and dual-cathode type MFC (DCMFC) were used to ascertain the current's improvement through an increase in the contact area between the anode and the cathode compartments, because the cathode reaction is one of the most serious limiting factors in an MFC. Also an MFC was conducted to explore whether an improvement in electricity generation resulted from oxidizing the carbon sources and nitrates. About 250 mg $L^{-1}$ sodium acetate was fed to an anode compartment with a flow rate of 0.326 mL $min^{-1}$ by continuous mode. The current generated from the DCMFC was higher than the value produced from MFC with a single cathode. COD removal of dual-cathode MFC was also higher than that of single-cathode MFC. The nitrate didn't affect current generation at 2 mM, but when 4 and 8 mM nitrate was supplied, the current in the single-cathode and dual-cathode MFC was decreased by 98% from $5.97{\pm}0.13$ to $0.23{\pm}0.03$ mA and $8.40{\pm}0.23$ to $0.20{\pm}0.01$ mA, respectively. These results demonstrate that increasing of contact area of the anode and cathode can raise current generation by an improvement in the cathode reaction.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.695-700
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• 2019

n this study, the evaluation of performance of AORFB using anthraquinone derivative and TEMPO derivative as active materials in neutral supporting electrolyte with various membrane types was performed. Both anthraquinone derivative and TEMPO derivative showed high electron transfer rate (the difference between anodic and cathodic peak potential was 0.068 V) and the cell voltage is 1.17 V. The single cell test of the AORFB using 0.1 M active materials in 1 M KCl solution with using Nafion 212 membrane, which is commercial cation exchange membrane was performed, and the charge efficiency (CE) was 97% and voltage efficiency (VE) was 59%. In addition, the discharge capacity was $0.93Ah{\cdot}L^{-1}$ which is 35% of theoretical capacity ($2.68Ah{\cdot}L^{-1}$) at $4^{th}$ cycle and the capacity loss rate was $0.018Ah{\cdot}L^{-1}/cycle$ during 10 cycles. The single cell tests were performed with using Nafion 117 membrane and SELEMION CSO membrane. However, the results were more not good because of increased resistance because of thicker thickness of membrane and increased cross-over of active materials, respectively.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.190-195
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• 2011

To investigate the photon-trapping effect and scattering layer effect of $TiO_2$ multi-layer in dye-sensitized solar cell (DSSC) and the degree of recombination of electrons at the electrode treated $TiCl_4$, we formed electrodes of different conditions and obtained the most optimal electrode conditions. To estimate characteristics of the cell, IV curve, UV-Vis spectrophotometer, electrochemical impedance spectroscopy (EIS) and incident photon-to-current conversion efficiency (IPCE) were measured. As a result, we confirmed that the multi-layer's efficiency was higher than that of monolayer in the IV curve and the performance of $TiCl_4$ treated electrode was increased according to decreasing the impedance of EIS. Among several conditions, the efficiency of the cell with scattering layer is higher than that of a layer with the base electrode about 19%. Because the light scattering layer enhances the efficiency of the transmission wavelength and has long electron transfer path. Therefore, the value of the short circuit current increases approximately 10% and IPCE in the maximum peak also increases about 12%.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.401-409
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• 2021

This study aimed to estimate the photosynthetic capacity of tomato plants grown in a semi-closed greenhouse using temperature response models of plant photosynthesis by calculating the ribulose 1,5-bisphosphate carboxylase/oxygenase maximum carboxylation rate (V_cmax), maximum electron transport rate (J_max), thermal breakdown (high-temperature inhibition), and leaf respiration to predict the optimal conditions of the CO₂-controlled greenhouse, for maximizing the photosynthetic rate. Gas exchange measurements for the A-C_i curve response to CO₂ level with different light intensities {PAR (Photosynthetically Active Radiation) 200µmol·m^-2·s^-1 to 1500µmol·m^-2·s^-1} and leaf temperatures (20℃ to 35℃) were conducted with a portable infrared gas analyzer system. Arrhenius function, net CO₂ assimilation (A_n), thermal breakdown, and daylight leaf respiration (R_d) were also calculated using the modeling equation. Estimated J_max, A_n, Arrhenius function value, and thermal breakdown decreased in response to increased leaf temperature (> 30℃), and the optimum leaf temperature for the estimated J_max was 30℃. The CO₂ saturation point of the fifth leaf from the apical region was reached at 600ppm for 200 and 400µmol·m^-2·s^-1 of PAR, at 800ppm for 600 and 800µmol·m^-2·s^-1 of PAR, at 1000ppm for 1000µmol of PAR, and at 1500ppm for 1200 and 1500µmol·m^-2·s^-1 of PAR levels. The results suggest that the optimal conditions of CO₂ concentration can be determined, using the photosynthetic model equation, to improve the photosynthetic rates of fruit vegetables grown in greenhouses.

• Journal of Life Science
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• v.27 no.12
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• pp.1445-1451
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• 2017

Mitochondria play a central role in energy generation by using electron transport coupled with oxidative phosphorylation. They also participate in other important cellular functions including metabolism, apoptosis, signaling, and reactive oxygen species production. Therefore, mitochondrial dysfunction is known to contribute to a variety of human diseases. Furthermore, there are various inherited diseases of energy metabolism due to mitochondrial DNA (mtDNA) mutations. Unfortunately, therapeutic options for these inherited mtDNA diseases are extremely limited. In this regard, mitochondrial replacement techniques are taking on increased importance in developing a clinical approach to inherited mtDNA diseases. In this study, green fluorescence protein (GFP)-tagged mitochondria were isolated by differential centrifugation from a mammalian cell line. Using microinjection technique, the isolated GFP-tagged mitochondria were then transferred to bovine oocytes that were triggered for early development. During the early developmental period from bovine oocytes to blastocysts, the transferred mitochondria were observed using fluorescent microscopy. The microinjected mitochondria were dispersed rapidly into the cytoplasm of oocytes and were passed down to subsequent cells of 2-cell, 4-cell, 8-cell, morula, and blastocyst stages. Together, these results demonstrate a successful in vitro transfer of isolated mitochondria to oocytes and provide a model for mitochondrial replacement implicated in inherited mtDNA diseases and animal cloning.

• Journal of Conservation Science
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• v.34 no.3
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• pp.179-193
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• 2018

This study is aimed to investigate the provenance of raw materials and firing temperature of jar coffins excavated from the Oryang-dong kiln site and Jeonchon tomb site, Naju, Korea. Most of jar coffin samples shows same range of magnetic susceptibility and have gray color, while 404 and 405 of Jeongchon site are reddish yellow. In some samples fired at high temperature, the water absorption at the mouth rim and body part of same jar coffin were 3.50% and 7.56% respectively. It means that heat transfer and equilibrium in the kiln was not properly continued and the heat energy transferred to the mouth rim and the body part was different. In the petrographic analysis, As a tempering materials, biotite, weathered quartz and feldspar were added in the jar coffins of Oryang-dong site, and biotite, polycrystalline quartz and feldspar in it of Jeongchon site. Tempering materials were found more in the body than in the mouth rim of same jar coffin of Oryang-dong site. It seemed that some samples were fired at over 1,000 to $1,100^{\circ}C$, which showed vitrified texture in the scanning electron images and the rest of samples were fired at below $900^{\circ}C$. Due to similarity of chemical compositions, it is estimated that jar coffins of Jeongchon tomb were produced and supplied from Oryang-dong kiln site. However, the slight difference of some trace elements distribution of samples is attributed to the selection of clay depending on the location.