• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.79-84
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• 2003

The main objective of this study was to investigate the chemical characteristics of post-harvest biomass burning aerosols from field burning of barley straw in late spring and rice straw in late fall in rural area in Korea. 12-hr integrated intensive sampling of $PM_{10}$ and $PM_{2.5}$ biomass burning aerosols had been conducted continuously at Gwangju, Korea 4-15 June 2001 and 8 October-14 November 2002. The fine and coarse particles of biomass burning aerosols were collected for mass, ionic, elemental, and carbonaceous species analysis. Average fine and coarse mass concentrations of biomass burning aerosols were measured to be 129.6, 24.2 ${{\mu}gm}^{-3}$ in June 2001 and 47.1, 33.2 ${{\mu}gm}^{-3}$ in October to November 2002, respectively. Exceptionally high level of $PM_{2.5}$ concentration up to 157.8 ${{\mu}gm}^{-3}$ well above 24-hour standard was observed during the biomass burning event days under stagnant atmosphere condition. During biomass burning periods dominant ionic species were $Cl^{-}$, ${NO_3}^{-}$, ${SO_4}^{2-}$, and ${NH_4}^{+}$ in fine and coarse mode. In the fine mode $Cl^{-}$ and ${KCl}^{+}$ were unusually rich due to the high content of the semiarid vegetation. High OC values and OC/EC ratios were also measured during the biomass burning periods. Increased amount of fine aerosols with high enrichment, which were originated from biomass burning of post-harvest agricultural waste, resulted in extremely severe particulate air pollution and visibility degradation in the region. Particulate matters from open field burning of agricultural wastes cause great adverse impact on local air quality and regional climate.

• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.48-55
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• 2015

IMO to issue some restricted maritime legislation for reducing the adverse environmental impacts arising from such ship exhaust emissions. According to the IMO policy, every ship entering the Baltic SECAs has to equip the gas cleaning scrubber. The discharged waste solution by gas cleaning scrubber contains many types of salts, which to recover some valuable materials before disposal. This study try to achieve valuable salts including AN and AS throughout a few process such as selective organic solvents salting out, low temperature extraction and thermal evaporation. Amongst them, Thermal evaporation with repetition extraction using inorganic solvent was the most optimum to purify the extracted AN. This valuable salt was evaluated by Elemental analysis and Differential scanning calorimetry.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.3.1-3.10
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• 2020

Objectives: This study investigated the indirect effect of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA), as 2 calcium silicate-based hydraulic cements, on human dental pulp stem cells (hDPSCs) through different dentin thicknesses. Materials and Methods: Two-chamber setups were designed to simulate indirect pulp capping (IPC). Human molars were sectioned to obtain 0.1-, 0.3-, and 0.5-mm-thick dentin discs, which were placed between the 2 chambers to simulate an IPC procedure. Then, MTA and CEM were applied on one side of the discs, while hDPSCs were cultured on the other side. After 2 weeks of incubation, the cells were removed, and cell proliferation, morphology, and attachment to the discs were evaluated under scanning electron microscopy (SEM). Energy-dispersive X-ray (EDXA) spectroscopy was performed for elemental analysis. Alkaline phosphatase (ALP) activity was assessed quantitatively. The data were analyzed using the Kruskal-Wallis and Mann-Whitney tests. Results: SEM micrographs revealed elongated cells, collagen fibers, and calcified nucleations in all samples. EDXA verified that the calcified nucleations consisted of calcium phosphate. The largest calcifications were seen in the 0.1-mm-thick dentin subgroups. There was no significant difference in ALP activity across the CEM subgroups; however, ALP activity was significantly lower in the 0.1-mm-thick dentin subgroup than in the other MTA subgroups (p < 0.05). Conclusions: The employed capping biomaterials exerted biological activity on hDPSCs, as shown by cell proliferation, morphology, and attachment and calcific precipitations, through 0.1- to 0.5-mm-thick layers of dentin. In IPC, the bioactivity of these endodontic biomaterials is probably beneficial.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.60-69
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• 2013

Purified melanin pigment from Klebsiella sp. GSK was characterized by thermogravimetric, differential thermal, X-ray diffraction and elemental analysis. This melanin pigment is structurally amorphous in nature. It is thermally stable up to $300^{\circ}C$ and emits a strong exothermic peak at $700^{\circ}C$. Its carbon, hydrogen and nitrogen composition is 47.9%, 6.9% and 12.0%, respectively. It was used to scavenge metal ions and free radicals. After immobilizing the pigment and using it to adsorb copper and lead ions, the metal ion adsorption capacity was evaluated by atomic absorption spectroscopy (AAS) and the identity of melanin functional groups involved in the binding of metal ions was determined by Fourier transform infrared (FT-IR) spectroscopy. Batch adsorption studies showed that 169 mg/g of copper and 280 mg/g of lead were adsorbed onto melanin-alginate beads. The metal ion adsorption capacity of the melanin-alginate beads was relatively significant compared to alginate beads. The metal ion desorption capacity of HCl was greater (81.5% and 99% for copper and lead, respectively) than that of EDTA (80% and 71% for copper and lead, respectively). The ability of the melanin pigment to scavenge free radicals was evaluated by inhibition of the oxidation of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and was shown to be about 74% and 98%, respectively, compared with standard antioxidants.

• Analytical Science and Technology
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• v.23 no.3
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• pp.322-329
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• 2010

Primer gunsot residues (GSR) obtained from K1A and K2 rifles, and K5 pistol were analysed with scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDX) as basic data in firearm accidents. Ammunition of 5.56 mm is employed for K1A and K2 rifles and 9.0 mm for a K5 pistol. The analyses of morphology, size, particle number, elemental ratio were performed for primer GSR prepared after shooting 3 times. The detected content was Ba>Pb>Sb in most GSR particles but Sb>Pb>Ba or Pb>Sb>Ba in some particles. In the statistical result of composition ratio of elements, the particles with more Sb than Ba were detected in most primer GSR from a K5 pistol, 3~8 times more than K1A and K2 rifles. This results can be employed to discriminate gun type between rifles and pistols. Furthermore, the size and the number of particles can be applied to access the type of guns.

• Asian Journal of Atmospheric Environment
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• v.7 no.4
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• pp.217-226
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• 2013

The collection of TSP and $PM_{2.5}$ aerosols has been made at the Gosan Site of Jeju Island during 2008-2011, and their ionic and elemental species were analyzed, in order to examine the seasonal variation and characteristics of aerosol compositions. The anthropogenic components ($NH_4{^+}$, $nss-SO_4{^{2-}}$, $NO_3{^-}$, S, Zn, Pb) and the soil components ($nss-Ca^{2+}$, Al, Fe, Ca) showed high concentrations in spring as the prevailing westerly wind, but the concentrations of the sea-salt components ($Na^+$, $Cl^-$) were high in winter. In TSP, the neutralization by $NH_3$ increased in summer, but the neutralization by $CaCO_3$ increased in spring and fall seasons. The organic acids ($HCOO^-$, $CH_3COO^-$) contributed to the acidification of the aerosols by only 5.0%, so the acidification could be mostly contributed by the inorganic acids ($SO_4{^{2-}}$, $NO_3{^-}$). From the examination of the source origins by factor analysis, the compositions of TSP were influenced by the order of soil > anthropogenic > marine, on the other hand, those of $PM_{2.5}$ were by the order of anthropogenic > marine > soil. The backward trajectory analyses showed that the concentrations of $NH_4{^+}$, $nss-SO_4{^{2-}}$, $NO_3{^-}$ and $nss-Ca^{2+}$ increased highly when the air masses had moved from China continent into Gosan area of Jeju Island.

• Journal of Conservation Science
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• v.36 no.4
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• pp.296-305
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• 2020

Konbaung Dynasty was the last unified dynasty that ruled Myanmar from 18^th to 19^th century. During this time Buddhist art flourished in Myanmar due to the interest of the rulers toward their traditional culture. Metal decorative artifacts in the 18^th century are classified into structures and Buddha statues. They are further subdivided into gilt-bronze and bronze objects, depending on their material component. Three-dimensional gilt-bronze decorative artifacts were cast with a brass alloy of Cu-Zn-Sn-Pb and their surfaces were gilded with extremely thin gold leaves (less than 1 ㎛ in thickness). The gilded layer approximately comprised 10 wt% silver in addition to the main element, gold. The lack of Hg in the gilded layer, indicated that the amalgam gilding technique was not applied. The analysis results indicated that the lacquered gilding technique was applied to the objects. Bronze decorative artifacts without gilding were cast with materials containing Cu-Sn-Pb. The bronze pavilions and bronze Buddha staues were crafted using the same alloy of high-tin bronze, which approximately contained 20 wt% Sn. No heat treatment was applied to reduce the brittleness of the objects after they were cast with a large amount of Sn. The most significant difference between the gilt-bronze and bronze decorative artifacts lie in their elemental compositions. The gilt-bronze decorative artifacts with their gilded surface were manufactured using brass containing zinc, while the unplated bronze decorative artifacts were composed of bronze containing tin. Artifacts of the same type and size are classified differently depending on the materials utilized in the surface treatment such as gilding.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.403-408
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• 1993

Hydroxypropyl chitin(HPCH) was prepared from chitin by reacting it with propylene oxide. The formation of liquid crystalline character of HPCH was investigated using halogenated organic solvents. Solid state $^{13}C$ NMR spectra for chitin and HPCH confirmed the incorporation of hydroxypropyl moiety. The degree of substitution of HPCH was around 0.8 as detected by elemental analysis. WAXD patterns of chitin and HPCH showed that an incorporation of hydroxypropyl unit in chitin contributed to reducing the crystallinity and enhancing the solubility in organic solvents. Polarized light microscopic pictures of concentrated HPCH solution showed that HPCH formed cholesteric liquid crystalline character at about 25w/v% solution in dichloroacetic acid and 1, 2-dichloroethane. Inherent viscosity of HPCH solution in a mixed solvent showed a transient decrease.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.381-392
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• 1993

Anionic oligomer surfactants, dodecyl polyoxyethylene ${\alpha}-sulfa$ alkanoates, had been synthesized through the esterification of dodecyl polyoxyethylene glycol and ${\alpha}-sulfa$ alkanoic acid with straight chain alkyl group having from 10 to 18 carbon atoms to good yield. ${\alpha}-sulfa$ alkanoic acids were obtained by reaction with long chain alkanoic acids and sulfur trioxide-dioxane complex, and dodecyl polyoxyethylene glycols, by addition reaction with dodecyl alcohol and ethylene oxide(addition, 5, 10, 20mol) respectively. All the synthetic products could be separated by means of the thin layer and column chromatography, and their structure has characterized with IR, $^1HNMR$ and elemental analysis, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.167-167
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• 2000

전지 재료의 충방전 과정 연구에는 X-선 분말회절(x-ray powder diffraction techniques)과 중성자회절을 많이 사용하였다. 하지만 이러한 분석기술은 long-range order의 구조에 관한 정보를 제공하는데 유용하지만 atomic scale의 구조에 관한 정보를 얻기에는 한계가 있다. Li 전지에서의 전기화학적 반응에서는 cathode 물질에 포함된 전이금속의 산화, 환원 반응에 의한 Li 이온의 intercalation (charge process)과 deintercalation (discharge process) 현상이 일어난다. 이러한 충방전 과정은 알려지지 않은 다양한 형태의 위상 변화를 동반하게 되는데 x-선 이나 중성자를 이용한 powder diffraction techniques 로는 단지 정성적인 결정학적 정보를 얻을 수 있다. 따라서 최근에 원자 단위의 local structure에 관한 정보와 electrochemical state에 관한 정보를 동시에 얻을 수 있는 X-ray Absorption Fine Structure (XAFS) 분석기술을 Li 전지분석에 활용하기 시작하였다. XAFS는 하나의 x-ray 흡수원자에 대해서 주변원자들의 원자구조에 관한 정보와 구성 원소의 electrochemical state에 관한 정보를 얻을 수 있는 분석방법이다. X-ray Induced Electron Emission Spectroscopy (XIEES)는 x-ray에 의해서 방출된 전자를 검출하여 스펙트럼을 얻는 기능을 함축적으로 나타낸 것으로, x-ray를 물질 표면에 조사하여 발생하는 광전자, Auger 전자, 이차전자 등을 전자검출기(Channel Electron Multiplier: CEM)로 검출하는 기능과, 시료를 투과한 x-ray와 시료에서 발생하는 형광 x-ray를 비례계수기로 검출하는 기능을 가지고 있다. 이러한 검출 능력을 바탕으로 EXAFS, XANES, Standing Wave Technique, Elemental Composition Analysis, DXRD, Total Reflection Technique 등을 이용하여 물질을 구성하고 있는 원소의 성분, 미세원자구조, 전자구조에 관한 정보를 얻을 수 있는 새로운 spectrometer이다. 본 연구에서는 자체 개발한 XIEES의 XAFS 기능을 이용하여 여러 가지 방법으로 제조한 LiMn2-xO4와 LiMnO2, MnO2에서 Mn K-absorption edge에 대한 chemical state 변화를 측정하였다. Absorption edge에서 chemical shift를 측정하기 위해서는 방사광 가속기 수준의 에너지 분해능(~0.3eV)이 필요하다. 이번 연구에서는 SiO2(3140) monochromator를 사용하고 여기에 맞는 적절한 parameter를 적용하여 x-ray 에너지 분해능을 포항방사광가속기 수준으로 개선하였다. XIEES에서 얻은 스펙트럼과 포항방사광가속기에서 얻은 스펙트럼을 비교하였다. Chemical shift가 일어나는 경향은 두 실험 결과가 잘 일치하였다.