• Korean Journal of Metals and Materials
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• v.49 no.5
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• pp.400-405
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• 2011

ZnO nanotube arrays were synthesized by a two-step process: electrodeposition and selective dissolution. In the first step, ZnO nanorod arrays were grown on an Au/Si substrate by using a homemade electrodeposition system. ZnO nanorod arrays were then selectively dissolved in an etching solution composed of 0.125 M NaOH, resulting in hollow ZnO nanotube arrays. It is suggested that the formation mechanism of the ZnO nanotube arrays might be attributed to the preferred surface adsorption of hydroxide ion ($OH^{-1}$) on a positive polar surface followed by selective dissolution of the metastable Zn-terminated ZnO (0001) polar surface caused by the difference in the surface energy per unit area between the ZnO nanorod and nanotube.

• Nuclear Engineering and Technology
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• v.11 no.2
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• pp.119-126
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• 1979

The reaction of 4,4'-dihydroxydiphenl methane (4,4'-DPM) with glycidyl methacrylate (GMA) catalyzed by triethylbenzyl ammonium chloride (TEBAC) has been studied for the purpose of synthesis of electron beam curable prepolymer. The reaction was in good agreement with third-order kinetics. according to -d[GMA]/dt=k[TEBAC][DPM][GMA] and the apparent activation energy was about 33.4kca1/mole. However, the reaction rates were increased if tile reaction proceeded after the mixtures exposed to air for 24 hrs at room temperature. The effects of the catalyst and the difference in the reactivity between 2.2'-DPM to GMA were discussed. The plausible reaction mechanism was proposed on basis of experimental data obtained.

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.440-444
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• 1998

Poly(phenylene sulfide-co-phenylene sulfide sulfone), PPS/PPSS copolymers were synthesized from p-dichlobenzene(DCB), p-dibromobenzene(DBB), p-diiodobenzene(DIB), 4-chlorophenyl sulfone(CPS) and sodium sulfide as comonomers under high temperature and pressure utilizing N-methyl-2-pyrrolidinone(NMP) as solvent. The yield of PPS/PPSS copolymer shoed maximum at $190^{\circ}C$ with [DBB]/[CPS] and [DIB]/[CPS] comonomer pair, while [DCB]/[CPS] pair exhibited maximum yield at $230^{\circ}C$. The change of yield is in the order of I>Br>Cl as leaving groups were in accordance with nucleophilic aromatic substitution reaction mechanism suggested for the synthesis of PPS type polymers. The molecular weight of PPS/PPSS copolymer was the highest($M_w=8,330g/mol$) with [DBB]/[CPS] comonomers in which [CPS] was 10 mole%. The PPS/PPSS copolymer made with 10 mole% of [CPS] showed about $15^{\circ}C$ higher $T_g$ and $15^{\circ}C$ lower $T_m$ than those of PPS homopolymer, which may be useful from the processing and thermal property point of view. The PPS/PPSS copolymer with 30 mole% of CPS or above did not exhibit Tm. The PPS/PPSS copolymer obtained with comonomer feed ratio of [DBB]/[CPS] = 95/5 mole% under $240^{\circ}C$ showed even higher molecular weight($M_w=10,300g/mole$) than PPS homopolymer made under similar reaction condition, retaining high crystallinity and thermal stability.

• Korean Journal of Weed Science
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• v.11 no.1
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• pp.26-31
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• 1991

The effects of varying concentrations and durations of ethalfluralin (N-ethyl-N-(2-methyl-2-propenyl)-2, 6-dinitro-4-(trifluoromethyl) bezenmine) treated on oat(Avena sativa L.) cell division, cell enlargement, protein synthesis and histology were studied. After 6hr treatment, all concentrations(1${\times}$10^{-6}M to $1{\times}10^{-3}$) of ethalfluralin arrested completely metaphase in the cell division study. The oat coleoptile inhibition of straight-growth test were used to determine the influence of ethalfluralin on coleoptile growth. A range of all concentrations($1{\times}10^{-8}$M to $1{\times}10^{-3}$M) treatment did affect cell enlagement significantly. The $1{\times}10^{-6}$M to $1{\times}10^{-3}$ M concentrations reduced approximately over 50% cell enlargement. Protein incorporation study showed that all concentrations($1{\times}10^{-6}$M to $1{\times}10^{-3}$M) were not affected in protein synthesis. To investigate histological effects, the oats were treated for 24hr with $1{\times}10^{-7}$M. The longitudinal section cells, in the treated oat root tips were appeared to be enlarged and also showed lacking cytoplasm, multinucleate or abnormal cells compare with untreated roots.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.652-659
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• 1997

For the effective utilization of the fish bone waste from seafood industry, the physical properties of the isolated hydroxyapatite from tuna bon have been investigated. On X-ray measurements, the chemical formula and phase of the bone calcined by various temperature were detected as $Ca_{10}\;(PO_4)_6\;(OH)_2$, and hydroxyapatite, respectively. It was shown that the chemical properties of apatite separated from tuna bone were controlled by Ca/P ratio. The mean agglomerate particle diameter was changed as a function of temperature. However, the particle shape has a geometrically non-regular types. These trends are consistent with SEM images. The composition of the glass-ceramic batch by calcined tuna bone was not perfectly agreed with the suggested data, but the partially substituted composition possibly shows the application of it as a bioceramic material.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.189-195
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• 2009

$\beta-Ga_{2}O_{3}$ nanorods were synthesized by chemical vapor deposition method using nickel-oxide nanoparticle as a catalyst and gallium metal powder as a source material. The average diameter of nanorods was around 160 nm and the average length was $4{\mu}m$. Also, we confirmed that the synthesis of nanorods follows the vapor-solid growth mechanism. From the results of X-ray diffraction and HR-TEM observation, it can be found that the synthesized nanorods consisted of a typical core-shell structure with single-crystalline $\beta-Ga_{2}O_{3}$ core with a monoclinic crystal structure and an outer amorphous gallium oxide layer. Li/$\beta-Ga_{2}O_{3}$ nanorods cell delivered capacity of 867 mAh/g-$\beta-Ga_{2}O_{3}$ at first discharge. Although the Li/$\beta-Ga_{2}O_{3}$ nanorods cell showed low coulombic efficiency at first cycle, the cell exhibited stable cycle life property after fifth cycle.

• Korean Journal of Weed Science
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• v.9 no.3
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• pp.245-249
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• 1989

The effects of varying concentrations and durations of butachlor [N-(bytoxymety 1,)-2-chlor -2, 6-diethy lacetanilide treatment on oat(Avena sativa L.) root cell division and protein synthesis were studied. The highest concentration ($1{\times}10^{-3}M$) of butachlor caused the significant inhibition of cell division after 18hrs treatment. After 18hrs treatment, 59% and 82% inhibition of cell division occurred at $1{\times}10^{-4}M$ and $1{\times}10^{-3}M$, respectively, while 9% inhibition of cell division did at $1{\times}10^{-6}M$ concentration at the same exposure period. To investigate protein synthesis, the oats were treated for 18 and 24hrs with concentrations ranging from $1{\times}10^{-6}M$ to $1{\times}10^{-3}M$ butachlor. After 18hrs, butachlor treatment of oat with $1{\times}10^{-4}M$ inhibitited 23% protein synthesis, and butachlor treatment with $1{\times}10^{-4}M$ caused 34% inhibition after 24hrs. With SDS-PAGE of proteins extracted from oat root tips, butachlor usually inhibited the 16, 18, 30, 43 and 43.5 kD polypeptide, and proteins of root tips are made up of subunits below 100 kD polypeptide.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.509-519
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• 1987

The tetradentate Schiff base ligand, 3,4-bis(salicylidene diimine) toluene, have been prepared by the reaction of salicylaldehyde with 3,4-diaminotoluene by Duff method. The Schiff base ligand reacts with Ni(II), Co(II), and Cu(II) ions to form new complexes, [Ni(o-BSDT)${\cdot}(H_2O)_2$], [Co(o-BSDT)${\cdot}(H_2O)$], and [Cu(o-BSDT)]. It seems that Ni(II) and Ni(II) complexes are hexacoordinated with the Schiff base ligand and two molecules of water, while the Cu(II) complexes are tetracoordinated with the Schiff base. The mole ratio of tetradentate Schiff base ligand to metals was found to be 1 : 1. The redox chemistry of these complexes was investigated by polarography and cyclic voltammetry with glassy carbon electrode in DMSO with 0.1M TEAP${\cdot}$[Ni(o-BSDT)${\cdot}(H_2O)_2$] hav EC reaction mechanisms which undergo a irreversible electron transfer followed by a fast chemical reaction. [Co(o-BSDT)${\cdot}(H_2O)_2$] undergoes a reduction of Co(II) to Co(I) and a oxidation of Co(II) to Co(III), and [Cu(o-BSDT)] undergoes a reduction of Cu(II) to Cu(I).

• Journal of Food Hygiene and Safety
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• v.39 no.2
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• pp.95-101
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• 2024

In this study, we investigated the migration level of items specified in the Korean Standards and Specifications for Utensils, Containers, and Packages (Ministry of Food and Drug Safety Notification) for 50 utensils and hygiene products made of biodegradable resins. Our results revealed that one Polylactide (PLA) baby tableware contained 20 mg/L in consumption of potassium permanganate, exceeding the standard of 10 mg/L or less. In all other samples, formaldehyde, lead (Pb), and arsenic (As) levels could be considered very safe and remained below the standard. Moreover, we tested the PLA baby tablewares (n = 21) for migration into a food simulant (4% v/v acetic acid) upon repeated elution at 100℃ for 30 min or UV irradiation for 2 h. We detected increased formaldehyde and As amounts at the repeated 100℃ treatment for 30 min compared to those upon repeated UV irradiation. However, the migration level was markedly low under both conditions. Furthermore, the Estimated Daily Intake (EDI) calculated on an infant-to-child basis from the formaldehyde and As migration at 100℃ for 30 min in the PLA sample was at the maximum value, i.e., 6.0×10^-4 mg/kg b.w./day and 1.3×10^-1 ㎍/kg b.w./day, corresponding to 0.40% and 10.42% of the Tolerable Daily Intake (TDI, 0.15 mg/kg b.w./day) and Provisional Tolerable Weekly Intake (PTWI, 9.0 ㎍/kg b.w./week), respectively. Therefore, in this study, we confirmed that biodegradable synthetic resins are safe to use for food.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.3
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• pp.199-208
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• 2019

As the number of available satellites increases and technology advances, image information outputs are becoming increasingly diverse and a large amount of data is accumulating. In this study, we propose a change detection method for high-resolution satellite images that uses transfer learning and a deep learning network to overcome the limit caused by insufficient training data via the use of pre-trained information. The deep learning network used in this study comprises convolutional layers to extract the spatial and spectral information and convolutional long-short term memory layers to analyze the time series information. To use the learned information, the two initial convolutional layers of the change detection network are designed to use learned values from 40,000 patches of the ISPRS (International Society for Photogrammertry and Remote Sensing) dataset as initial values. In addition, 2D (2-Dimensional) and 3D (3-dimensional) kernels were used to find the optimized structure for the high-resolution satellite images. The experimental results for the KOMPSAT-3A (KOrean Multi-Purpose SATllite-3A) satellite images show that this change detection method can effectively extract changed/unchanged pixels but is less sensitive to changes due to shadow and relief displacements. In addition, the change detection accuracy of two sites was improved by using 3D kernels. This is because a 3D kernel can consider not only the spatial information but also the spectral information. This study indicates that we can effectively detect changes in high-resolution satellite images using the constructed image information and deep learning network. In future work, a pre-trained change detection network will be applied to newly obtained images to extend the scope of the application.