• Analytical Science and Technology
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• v.17 no.2
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• pp.173-179
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• 2004

The $BaTiO_3$ powders and thin films were prepared by an alkoxide modified sol-gel process (polymerization-complex route) using ethylene glycol. The stable starting (Ba-Ti)-mixed metal organic sol was made by addition of acetylacetone. The $BaTiO_3$ powders, which had a particle size of 40~77 nm, were crystallized from an amorphous to a tetragonal phase on annealing at 700 and $1100^{\circ}C$ for 1 h. From FT-IR, solid-state $^{13}C$ CP/MAS NMR spectroscopy and X-ray diffractometry, the trace of the Ba-Ti-oxycarbonate phase first appeared at $400^{\circ}C$. Hydrolyzed sol was spin coated on a quartz wafer at 3500 rpm for 60 s and pyrolyzed at $1100^{\circ}C$ for 1 h. After heat treatment, the coated layer became dense and smooth.

• Analytical Science and Technology
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• v.11 no.1
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• pp.1-7
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• 1998

This study focuses on developing a controlling and analyzing software for the portable atomic emission spectrometer equipped with an electrothermal vaporizer(ETV) that can perform the in-situ trace analysis of heavy metal ions dissolved in water. The software works well for a notebook PC and it is exclusively developed for the real time analysis with a line filter and a photomultiplier light detector. The program is designed to operate under Windows 95 environment and either Korean or English can be used as a main language. The Delphi 2.0 language software is mainly used for programing. The program is designed to make a calibration curve and the system users can get the analytical data in a short time. And a final report can be generated without having difficulties. This software can be easily modified for other analytical atomic spectrometers.

• Analytical Science and Technology
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• v.17 no.1
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• pp.8-15
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• 2004

The detection efficiencies of the several solid track detectors were investigated for the determination of boron content in aqueous solution by using the alpha muti-Radioisotope(RI) source. Polycarbonate (Lexan and CR-39) and cellulose nitrate (CN-85 and LR-115) were selected as materials for alpha track detection of boron. Alpha muti-RI source, uranium metal particles and boron standard solution were used for alpha emission. In this study, four solid track detectors(CN-85, LR-115, Lexan and CR-39) were characterized under various etching conditions as well as neutron irradiation conditions. As a result, the CN-85 was turned out to be best to provide good efficiency among the four detectors. The selected solid track detector was utilized for the determination of trace amount of boron in aqueous sample and its results were discussed in the text.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.61-62
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• 2007

HVOF thermal spray coating of micron size Co-alloy powder has been studied for the durability improvement of high velocity spindle (HVS). Optimal coating process of this system for the best surface properties is hydrogen flow rate 75 FMR, oxygen flow rate 38-42 FMR, feed rate 30 g/min at spray distance 5 inch. Friction coefficient (FC) and wear trace (WT) decrease increasing coating surface temperature from 25$^{\circ}$C to 538$^{\circ}$C due to the higher lubricant effects of the oxides at the higher temperature. At the study of adhesion of T800 coating on a light metal alloy Ti-6Al-4V (Ti64) tensile bond strength (TBS) and tensile fracture location (TFL) of Ti64/T800 are 8,740 psi and near middle of T800 coating respectively. This shows that adhesion of Ti64/T800 is higher than the cohesion strength (8,740 psi) of T800 coating. Therefore T800 coating is strongly advisable for the surface coating on HVS such as high speed air-bearing spindle.

• Resources Recycling
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• v.10 no.4
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• pp.34-41
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• 2001

A research was performed to evaluate a use of shredder residue to currently dispose of at landfills. Laboratory analyses were conducted to determine especially the fuel characteristics of shredder residue. For this aim, shredder residue was classified by the particle size as well as by the type of material and the content of Cl, S, ash, and calorific value were determined. Due to the chlorinated plastic content of shredder residue, mean concentration of Cl was found to exceed 4wt% except one sample while that of S was ranged from 0.25 to 0.39 wt%. As far as calorific value was concemed, plastic was observed to be more than 10,000 kcal/kg while wood/paper and fiber accounted for approximately 4,000 kcal/kg. Shredder residue was found to contain varying trace amounts of metal elements, including Fe of 6∼8.5 wt%. Hg and Cr(VI) were not detected, however, while Cd was contained as small as 0.0004-0.0009 wt%.

• Journal of the Korean earth science society
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• v.43 no.5
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• pp.569-578
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• 2022

Oceanic Anoxic Event 2 (OAE2) represents a period of mid-Cretaceous when black shale was deposited worldwide. This short period of perturbations in the global biogeochemical cycles spans the Cenomanian-Turonian boundary, marking the peak of the Cretaceous greenhouse, which is characterized by elevated atmospheric pCO₂, sealevel highstand, and expansion of oxygen minimum zone. Since the pioneering work in the 1970s, numerous studies have investigated the cause and consequences of the event based on geochemical and isotope proxies, and it is now widely accepted that the enhanced primary production and volcanism during the Cenomanian-Turonian boundary interval were the key environmental factors that triggered OAE2. This study briefly reviews previous OAE2 studies of the carbon, sulfur, and trace metal cycles for mechanistic understanding of the biogeochemical processes during the event.

• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.39-49
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• 2022

Bottom ash generated from thermal power plants is mainly disposed in landfills, from which metals may be leached by infiltrating water. To evaluate the effect of metals in leachate on soil and groundwater, we characterized bottom ash generated from burning cokes, bituminous coal, the mixture of bituminous coal and wood pellets, and charcoal powder. The bottom ash of charcoal powder had a relatively large particle size, and its wood texture was well-preserved from SEM observation. The bottom ash of charcoal powder and wood pellets had relatively high K concentration from total element analysis. The eluates of the bottom ash samples had appreciable concentrations of Ca, Al, Fe, SO₄, and NO₃, but they were not a significant throughout the batch test. Therefore, it is considered that there is low possibility of soil and groundwater contamination due to leaching of metal ions and anions from these bottom ash in landfills. To estimate the trend of various trace elements, long-term monitoring and additional analysis need to be performed while considering the site conditions, because they readily adsorb on soil and aquifer substances.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.106-110
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• 2023

Lignin is compatible with various polymeric materials and useful as a carbon precursor. In this work, carbon monolith films were produced from polyacrylonitrile (PAN)@lignin precursor films by a controlled carbonization cycle. In addition, their morphological features, electrical properties, and adsorption behavior were analyzed and compared with those of carbonized PAN films. The successful formation of PAN@lignin precursor was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. SEM was used to examine the morphology of precursor and carbonized films, revealing that both precursor and carbonized films retained structural stability following carbonization. A trace of lignin in the carbonized films was also found. The pore structure of the carbonized PAN@lignin film was measured using the BET method, indicating the formation of fairly uniform pores. The electrical properties were also analyzed to obtain the Ohmic relation, which demonstrated that the electrical signal was influenced by incoming materials. Finally, the carbonized PAN@lignin films were useful as adsorbents to remove metal ions. This study provides important information for future initiatives in relevant research fields.

• Advances in nano research
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• v.14 no.4
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• pp.313-327
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• 2023

Zinc metal organic framework (MOF_Zn)-loaded goad nanoparticles (AuNPs) sol (Au@MOF_Zn), which was characterized by TEM, Mapping, FTIR, XRD, and molecular spectrum, was prepared conveniently by solvothermal method. The results indicated that Au@MOF_Zn had a very strong catalytic effect with the nanoreaction of AuNPs formation between sodium oxalate (SO) and HAuCl4. AuNPs in the new indicator reaction had a strong resonance Rayleigh scattering (RRS) signal at 370 nm. The indicator AuNPs generated by this reaction, which had the most intense surface enhanced Raman scattering (SERS) peak at 1621 cm -1. The new SERS/RRS indicator reaction in combination with specific aptamer (Apt) to fabricate a sensitive and selective Au@MOF_Zn catalytic amplification-aptamer SERS/RRS assay platform for carbendazim (CBZ), with SERS/RRS linear range of 0.025-0.5 ng/mL. The detection limit was 0.02 ng/mL. Similarly, this assay platform has been also utilized to detect oxytetracycline (OTC) and profenofos (PF).

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.1
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• pp.36-44
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• 2015

The spatial and temporal distribution of dissolved trace metals has been studied to identify trends in space and time and to evaluate the pollution status in a semi-closed bay (Gohyun bay), Korea. Surface seawater samples were collected over four seasons at 18 stations in the bay between 2003 and 2004 and once at 7 stations around a large shipyard in May 2004. The concentration of Cd, Co, Cu, Ni, Pb, and Zn in seawater in February and May were highly variable in space, showing the higher value relative to other season. Those metals concentrations were decreased from inner-to outer-stations. In around the shipyard, Cu, Pb and Zn showed the higher variability depending on time. Cu and Zn concentrations at the sites around the shipyard had 2 times higher values compared with the average of inner stations in Gohyun bay. The very high correlations between salinity and either Cu and Zn has been showed. Especially, there was a significant relationship between Cu and Zn. We recognize that the shipyard is major source of Cu and Zn in seawater. Therefore, marine environment management policy such as the prevention and control of heavy metal input from a shipyard is required.