• Food Science and Industry
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• v.54 no.1
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• pp.29-33
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• 2021

Particulate matter (PM) is an air pollutant that causes serious environmental problems in Korea and other countries. The annual average PM10 concentration in Korea is around 40 ㎛/㎥, which is more than twice as high as the WHO recommended standard. When consumed with food, fine PM can pose a risk to humans. However, the risk of fine PM has been focused on the risk of fine PM introduced through the respiratory system. We investigated the quantitative measuring methods of PM10 on food surface to identify possible risk analysis of fine PM. The surfaces of food with artificially contaminated PM10 were observed with a scanning electron microscope(SEM). An automatic object-based image analysis was used to analyze the amount and size distribution of particulate matter contained in SEM micrographs.

• Journal of Species Research
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• v.11 no.4
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• pp.253-265
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• 2022

A study on silica-scaled chrysophytes(Chrysophyceae and Synurophyceae) from Mt. Sinbul alpine wetland, South Korea was performed from January 2018 to March 2020 using scanning electron microscopy (SEM). We found a total of 19 taxa of silica-scaled chrysophytes; Mallomonas(13); Synura (3); Chromophysomonas (1); Chrysosphaerella (1); and Paraphysomonas(1), of which six taxa, including two new species(Mallomonas dimorphus sp. nov. and Mallomonas alpestris sp. nov.), were reported for the first time in Korea. All the species are illustrated with SEM micrographs and briefly described with regard to their taxonomy. Two new species were described based on the cell shape, size and ultrastructure of the scales and bristles. Mallomonas dimorphus sp. nov. belongs to the Sectio Heterospinae in that its scales have a flat dome, a reticulated secondary layer and needle shaped bristles. However, this species is distinguished from other taxa in the Sectio by two different patterns of shield ornamentation and a dome ornamentation. Mallomonas alpestris sp. nov. belongs to Series Torquatae (Sectio Torquatae) characterized elongated domed collar scales, domeless body scales and rear scales with a short spine. However, it is different from all other taxa in the Sectio Torquatae as well as Series Torquatae by shield ornamentation of the body and rear scales with evenly spaced transverse ribs and papillae.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.919-927
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• 2002

In order to fabricate double-layered porous materials powders of different particle sizes were pressed stepwise. Ford＇s equation which predicts the fired density with the change in pressed density was employed in order to adjust the difference in sintering shrinkage of the green body with double-layered porous structure. Double-layered porous materials were characterized by investigating microstructures and permeability. SEM micrographs showed the distinct difference in pore sizes of double-layered porous material. Permeability of single-layered porous material increased by increasing the starting particle sizes and porosity as well. Permeability of the double-layered porous material depends largely on the layer of small pore diameter.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.37-43
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• 1998

The mechanism of interaction between low energy ions and biological organisms has been paid much attention recently. In order to clarify the microstructural response to low energy ion irradiation embryonic cells of Paeonia rockii L. implanted by $Fe^{1+}$ ions with the energy of 80KeV were investigated by Optical Microscopy (OM), Scanning electron Microscopy(SEM) and Transmission Electron Microscopy(TEM). At the dose of 1$\times$1015 ions/$\textrm{cm}^2$, apparent cellular damage was observed in the outer several layers of the radicle. The shape of the cells was obviously deformed from regular polygon to irregular. The cell walls became obscure. SEM micrographs showed that the surface of the radicle was etched severely. It was observed by TEM that nucleus of the implanted cell was elongated and tended to fracture. Nuclear envelope lost its integrity. The implanted $Fe^{1+}$ ions were detected by Energy Dispersive Spectroscopy (EDS). These observations showed that low energy ions could damage to the plant organisms with the thickness of about 30~50$\mu\textrm{m}$. The possible reasons for radiation damage in the biological organisms were discussed.

• Carbon letters
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• v.10 no.3
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• pp.181-189
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• 2009

Activated carbon spheres (ACS) were prepared at different heating rates by carbonization of the resole-type phenolic beads (PB) at $950^{\circ}C$ in $N_2$ atmosphere followed by activation of the resultant char at different temperatures for 5 h in $CO_2$ atmosphere. Influence of heating rate on porosity and temperature on carbon structure and porosity of ACS were investigated. Effect of heating rate and temperature on porosity of ACS was also studied from adsorption isotherms of nitrogen at 77 K using BET method. The results revealed that ACS have exhibited a BET surface area and pore volume greater than $2260\;m^2/g$ and $1.63\;cm^3/g$ respectively. The structural characteristics variation of ACS with different temperature was studied using Raman spectroscopy. The results exhibited that amount of disorganized carbon affects both the pore structure and adsorption properties of ACS. ACS were also evaluated for structural information using Fourier Transform Infrared (FTIR) Spectroscopy. ACS were evaluated for chemical composition using CHNS analysis. The ACS prepared different temperatures became more carbonaceous material compared to carbonized material. ACS have possessed well-developed pores structure which were verified by Scanning Electron Microscopy (SEM). SEM micrographs also exhibited that ACS have possessed well-developed micro- and meso-pores structure and the pore size of ACS increased with increasing activation temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.522-531
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• 2003

Samples with the nominal composition, B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+{\delta}}$ high- $T_{c}$ superconductors containing MgO as an additive were fabricated by a solid-state reaction method. Samples with MgO of 5~30 wt% each were sintered at 820~86$0^{\circ}C$ for 24 hours. The structural characteristics, critical temperature, grain size and image of mapping with respect to MgO contents were analyzed by XRD(X-Ray Diffraction), SEM(Scanning Electron Microscope) and EDS(Energy dispersive X-ray spectrometer) respectively. As MgO contents increased, intensity of MgO Peaks and ratio of Bi-2212 phase in superconductors intensified and the proportion of the phase transition from Bi-2223 to Bi-2212 was increased.

• Korean Journal of Materials Research
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• v.25 no.5
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• pp.247-252
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• 2015

The effect of precursor concentration on the structural, morphological, and optical properties of $TiO_2$nano-flowers was investigated in this study. An increase in crystallite size was observed with an increase in the concentration of the precursor (titanium butoxide). The FE-SEM micrographs of the as-prepared samples show a three-dimensional flower-like morphology. The flowers consist of several nanorods coming out of a single core and have very sharp edges. Also, the variation in the aspect ratio of the nanostructure was observed with the concentration of the precursor. The photocatalytic properties of the samples show that the sample that has a high aspect ratio (AR~9) has a much better photocatalytic activity compared to the nano-crystal with a low aspect ratio (AR~6.1). It is believed that the excellent photocatalytic performance and short time synthesis of $TiO_2$nano-flowers using the microwave hydrothermal method can have potential applications in the field of photocatalysis.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.572-576
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• 2002

This investigation was designed to estimate the biaxial flexure strength and fracture toughness of lithium disilicate glass-ceramics of IPS Empress 2 system pressed with as-received ingots and their sprue buttons. Two groups of the lithium disilicate glass-ceramics were prepared as follows: group 1 is ingot-pressed group; group 2 is sprue button-pressed group. A ball-on-three-ball test was used to determine biaxial flexure strength (BFS) of disks in wet environment. Scanning electron microscopy(SEM) analysis was conducted to observe the microstructure of the ceramics. Unpaired t-test showed that there were no differences in the mean biaxial Hem strength (BFS) and KIC values between group 1 and 2 (p > 0.05). Two groups showed similar values in the KIC and the strength at 5% failure probability. The SEM micrographs of the IPS Empress 2 glass-ceramic showed a closely packed, multi-directionally interlocking pattern of numerous lithium disilicate crystals protruding from the glass matrix. The lithium orthophosphate crystals could not be observed on the fracture surface etched. There was no a marked difference of the microstructure between group 1 and 2. Although there were no tests including color stability, casting accuracy, etc., the results of this study implied that we could reuse the sprue button of the pressed lithium disilicate glass-ceramic of IPS Empress 2 system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1255-1258
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• 2010

In this paper, the $CoSi_2$ thin films with thicknesses of about $5{\mu}m$ were deposited on n-type silicon (111) substrates by RF magnetron sputtering method using a $CoSi_2$ target (99.99%). The flow rate of argon of 50 sccm, substrate temperature of $100^{\circ}C$, RF power of 60 watts, deposition time of 30 minutes, and the vacuum of $1\times10^{-6}$ Torr. The annealing treatments of the $CoSi_2$ thin film were performed from 500, 700 and $900^{\circ}C$ for 1h in air ambient by an electric furnace. In order to investigate the $CoSi_2$ thin film X-ray diffraction patterns were measured using the X-ray diffractometer (XRD). The structure of the thin films were investigated by using scanning the electron microscope (SEM) were used for review. The surface morphology of the thin films was measured with a atomic force microscopy (AFM). Temperature dependence of sheet resistivity and property of Hall effect was measured in the $CoSi_2$ thin film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.231-237
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• 2003

RE(Nd, Sm) elements doped (RE/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(RE/Y)1.8] high $T_{c}$ superconductors were directionally grown by Top Seed Melt Growth(TSMG) process in air atmosphere. The (001)melt-textured N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$ $O_{7-X}$(Nd1.8) seed crystals were used for achieving the c-axis alignment large grains perpendicular to surface of the samples. The (RE/Y)1.8 SEM micrographs of the melt-textured (RE/Y)1.8 samples revealed that the nonsuperconducting (RE/Y)211 inclusions are uniformly distributed in the superconducting (RE/Y)123 matrix except the region very close to the Nd seed crystal. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The Melt-textured (RE/Y)1.8 samples showed an onset $T_{c}$=91K and sharp superconducting transition. Also, the magnetization value of the (RE/Y)1.8 samples were compared with those of Y1.8 sample at 77 K. 77 K. 77 K. 77 K.K.