• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.646-651
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• 2018

This paper reports that the electronic properties at a $P3HT/TiO_2$ interface associated with exciton dissociation and transport can be tailored by the insertion of a graphene quantum dot (GQD) layer. For donor/acceptor interface modification in an $ITO/TiO_2/P3HT/Al$ photovoltaic (PV) device, a continuous GQD film was prepared by a sonication treatment in solution that simplifies the conventional processes, including laser fragmentation and hydrothermal treatment, which limits a variety of component layers and involves low cost processing. The high conductivity and favorable energy alignment for exciton dissociation of the GQD layer increased the fill factor and short circuit current. The origin of the improved parameters is discussed in terms of the broad light absorption and enhanced interfacial carrier transport.

• Membrane Journal
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• v.24 no.3
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• pp.201-212
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• 2014

This study was performed to discover the optimum operation conditions for the advanced water treatment using the ceramic membrane, introduced the first in the nation at the Y water treatment plant (WTP). The result of investigation to find the optimum operation conditions which can continue preserving the filtration performance as well as satisfying both the economics and the water quality is as follows. In the ordinary water quality condition of the Y WTP, the optimum filtration time(the backwash period), which can minimize the production of backwash waste and preserve the membrane performance was examined to be 4.0 hours on basis of institution capacity ($16,000m^3/day$). Examining the recovery rate of TMP from the chemical cleaning (CIP) discovered that the inorganic contaminants, which cause membrane fouling, such as iron, manganese, aluminum, were removed through the acidic cleaning using citric acid, whereas the membrane recovery rate was found to be low. But, on the other hand, the TMP was recovered to the initial value from the alkali cleaning using the NaOCl. Therefore, the main contaminant causing the fouling was determined to be hydrophilic organic compound( biopolymer). The membrane recovery rate is highly influenced by the temperature of the cleaning chemical. That is, the rate increased with increasing temperature.

• Journal of Conservation Science
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• v.28 no.2
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• pp.141-151
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• 2012

It was the 1900s that the damaged materials of stone heritages began to be preserved and managed for the purpose of reuse, especially since cement, an inorganic material, began to be used during the Japanese colonial period. Epoxy resin, an organic material, was introduced to architecture around the turn of the 1990s, and has been being used across the board. In particular, filler mixtures began to be aggressively used for the structural reinforcement of severed materials. The problem was metal stiffeners used for structural reinforcement. The anchorage length varied depending in different conservation scientists, and as a result the secondary damage was apt to occur in the materials. In this study, hereat, a calculation was made of the most effective anchorage length with the minimization of material damage. The results were as in the following: the anchorage length of an 8-milimeter-across (ø8) metal stiffener was found to be most effective at 60.88mm. Those of ø12 and ø16 were 60.88mm and 91.32mm respectively. In the case of other calibers, the anchorage length was calculated by a formula ${\ell}_d=a_tf_y/u{\Sigma}_0$. In the experiment, helically-threaded round bars were used as metal stiffeners in order that they could bear surcharge loads such as bending, shear and constriction.

• Applied Microscopy
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• v.40 no.3
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• pp.155-162
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• 2010

Bone is a hierarchically structured composite material which has been well studied by the materials engineering community because of its unique structure and mechanical properties. Bone is a laminated organic-inorganic composite composed of primarily hydroxyapatite, collagen and water. The main mineral that gives bone's hardness is calcium phosphate, which is also known as hydroxyapatite. Light microscopy (LM) and transmission electron microscopy (TEM) were used to study the structure of femurs from chicken and rabbit. The elemental analysis was used to search variation in the distribution of calcium, potassium and oxygen in the femur. Current investigation focused on two structural scales: micro scale (arrangement of compact bone) and nano scale (collagen fibril and apatite crystals). At micro scale, distinct difference was found in microstructures of chicken femur and rabbit femur. At nano scale, we analyzed the shape and size of apatite crystals and the arrangement of collagen fibril. Consequently, femurs of chicken and rabbit had very similar chemical property and structures at nano scale despite of their different species.

• Journal of Life Science
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• v.18 no.6
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• pp.839-844
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• 2008

A strain SH-517 which produce extracellular keratinase, was isolated from the soil of a poultry waste and a poultry factory. An isolate SH-517 was identified as Bacillus sp. based on its morphological and biochemical characteristics. The optimal culture conditions for the production of keratinase by Bacillus sp. SH-517 were investigated. The optimal medium composition for keratinase production was determined to be 2.0% chicken feather as carbon source, 0.5% beef extract as organic nitrogen source, 0.5% $KNO_3$ as inorganic nitrogen source and 0.06% KCl, 0.05% NaCl, 0.04% $KH_2PO_4$, 0.03% $K_2HPO_4$ as mineral source and 0.01% yeast extract as growth factor. The optimal temperature and pH of medium were shown $40^{\circ}C$ and 8.5 with shaking culture (180 rpm/min), respectively. The maximum keratinase production reached maximum of 125 units/ml/min after 42 hr of cultivation under the optimal culturing conditions.

• Journal of Life Science
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• v.18 no.12
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• pp.1671-1678
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• 2008

We investigated the effect of the turbid water on the phytoplankton community in the 4 sites of Imha reservoir. The turbidity of water was proportional to the concentrations of $SiO_2$-Si. Therefore, as the turbidity of water grow, the concentration of $SiO_2$-Si increased. And the both the turbidity of water and the concentrations of $SiO_2$-Si were increased as the water run deep. The concentration of chlorophyll-a decreased as the depth of water increased. Seventy phytoplankton taxa were identified and the most abundant group was Chlorophyceae consisting of 32 taxa (46%), and Cyanophyceae and Bacillariophyceae consisted of 12 taxa (17%). And Euglenophyceae, Synulophyceae, Cryptophyceae and Dinophyceae consisted of 6 taxa (9%), 4 taxa (6%), 3 taxa (4%) and 1 taxon (1%), respectively in Imha reservoir. The concentrations of phytoplankton were increased according to the turbidity of water because of the high amount of organic nutrition which is presented with turbid water. And especially, the concentrations of nitrogen increased easily because of the weak binding to the soil particle. In conclusion, total nitrogen and $SiO_2$-Si flowed into the Imha reservoir with soil particle, and these inorganic nutritions affect the growth of algae.

• Applied Biological Chemistry
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• v.13 no.1
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• pp.51-57
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• 1970

On the basis of the specific interrelationship between the species or variety of leguminous crops and the species or strain of nodule bacteria, Rhizobia, the rhizobial species and strain must be effectively chosen for the successful inoculation. The present paper describes on some results of the isolation and taxonomic study on the native rhizobial strains isolated from the nodules of five species of leguminous crops such as numerous varieties of soy bean, lespedeza, birdfoot trefoil, ladino and red clovers. The isolated strains of soy bean nodule bacterium, Rhizobium japonicum were grouped through the inoculation test on variety Changdanbaikmock into the effective, noneffective and toxic strain for the nodule formation. In the study of the effect of some inorganic and organic nitrogenous compounds on the growth of Rhizobium japonicum strain Ac 20, a promotive response was showed by asparagine, and glutamine, but hydroxylamine, nitrite, hydrazine and azide was inhibitory at the concentration of $10^{-2}M/l$ in mannitol-yeast extract basal medium. In the physiological characteristics each strain showed somewhat different activities of the indole-3-actic acid formation and hydrogenase and discussed with these characters in relation to nodule forming ability.

• Membrane Journal
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• v.19 no.2
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• pp.96-103
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• 2009

A series of organic-inorganic composite membranes from poly(vinyl chloride) (PVC) graft copolymer electrolyte and heteropolyacid (HPA) were prepared for proton conducting membranes. First, poly(vinyl chloride)-g-poly(styrene sulfonic acid) (PVC-g-PSSA) was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC. HPA nanoparticles were then incorporated into the PVC-g-PSSA graft copolymer though the hydrogen bonding interactions, as confirmed by FT-IR spectroscopy. The proton conductivity of the composite membranes increased from 0.049 to 0.068 S/cm at room temperature with HPA contents up to 0.3 weight traction of HPA, presumably due to both the intrinsic conductivity of HPA particles and the enhanced acidity of the sulfonic acid of the graft copolymer. The water uptake decreased from 130 to 84% with the increase of HPA contents up to 0.45 of HPA weight traction, resulting from the decrease in number of water absorption sites due to hydrogen bonding interaction between the HPA particles and the polymer matrix. Thermal gravimetric analysis (TGA) demonstrated the enhancement of thermal stabilities of the composite membranes with increasing concentration of HPA.

• Membrane Journal
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• v.18 no.3
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• pp.191-197
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• 2008

In this study, we used hybrid module that was composed of packing granular activated carbon (GAC) between module inside and outside of ceramic microfiltration membrane for advanced drinking water treatment. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, synthetic water was prepared with humic acid and kaolin. Packing fraction of GAC was changed from 0 to 24.05% to see effect of packing fraction. As a result, changing curves of resistance of membrane fouling ($R_f$) and permeate flux (J) during 3 h operation were almost overlapped independent of packing fraction of GAC. Treatment efficiencies of turbidity were very high above 99.46% at all packing fractions of GAC. And treatment efficiency of NOM, which was measured by $UV_{254}$ absorbance, was the highest value of 99.43% at packing fraction of 24.05%. Then, we operated the hybrid process during 13 h at packing fraction of 24.05%. As a result, J was rapidly dropped according to increase of membrane fouling within initial 1 h of operation, and almost constant after 3 h. And treatment efficiencies of turbidity and NOM were stable and high values of 99.52% and 96.63%, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.463-471
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• 2000

A pot experiment was carried out to find out the effects of the sludge application on corn and Chinese cabbage growth and changes in soil chemical properties with sludges collected from 4 plants at 0, 12.5, 25, 50, and $100Mg\;ha^{-1}$ levels and chemical fertilizer. With the corn experiment, the pot where sludge and chemical fertilizers were treated together, greater amount of sludge resulted in initial growth inhibition. In general, higher sludge treatment rates resulted in better growth in the end, whereas initial growth was inhibited due to high the electrical conductivity of saturated extracts(ECe) for the Chinese cabbage. However, the highest yield among sludge treatments was lower than the yield with chemical fertilizers. While the treatments resulted in chemical changes in soil showing differences of cation exchange capacity, organic matter contents, and nitrogen contents, hardly any changes were detected before and after crops were grown. Inorganic nutrients such as Na, K, Ca and Mg showed similar changes. The ECe in soil saturation extract decreased after crops were grown. The more sludge was treated, the greater was the decrease. The differences of ECe in the soil saturation extract with varying degrees of treatment were also reduced after crops were grown. Available phosphorus content increased during growth. Due to the low nitrogen content in sludge, when nitrogen becomes the determining factor for the amount of sludge treatment, phosphorus buildup resulted from continued application of sludge could be raised. Therefore, it is advisable to use phosphorus, not nitrogen content, in determining the amount of sludge treatment and chemical fertilizer as supplementary sources for nitrogen.