• Journal of the Korean Magnetics Society
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• v.19 no.6
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• pp.209-215
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• 2009

M-type barium ferrite (BaFe12O19) powders were synthesized through the co-precipitation method. Starting material composition $Fe^{3+}:\;Ba^{2+}$ mole ratio was fixed as 8 and the relative amount of $Fe^{3+}$ and $Ba^{2+}$ was controlled. Structure and magnetic properties and powder morphology were investigated using XRD, SEM, VSM. Powder showing high coercivity and small magnetization was obtained at pH8 and $Fe_{3+}:\;Ba_{2+}$ of 12 : 1.5. Small magnetization value was originated from the existence of ${\alpha}-Fe_2O_3$. Single-phase Mtype barium ferrite were obtained regardless of the heat treatment condition and the amount of $Fe_{3+}\;and\;Ba_{2+}$ at pH$\approx$10. The largest value of magnetization (55.7 emu/g) under investigation were obtained when $Fe_{3+}:\;Ba_{2+}$ of 13.6 : 1.7 and furnace cooled powder in $O_2$. Particle size of powder was in the range of 50~200 nm.

• Applied Microscopy
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• v.37 no.2
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• pp.73-82
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• 2007

The antennae of millipedes have a prominent function in detecting various types of environmental stimuli. The structural modification of the antennae is closely associated with the degree of sense recognition. Here we study functional morphology of the antennae of the millipede Cawjeekelia pyongana using field emission scanning electron microscope (FESEM). The antennae generally include eight segments, called articles. On the surface of the antennae, there are a variety of sensory receptors which include olfactory and mechanical receptors. We could identify four different types of antennal sensory organs in C. pyongana as follows: apical cone (Ac), trichoid sensilla (Ts), chaetiform sensilla (Cs) and basiconic sensilla (Bs). The most prominent of which is four APs at the 8th article. Both of the Is and the Cs are abundantly observed almost all of the antennal segments. They are long and strong bristles with longitudinal grooves acuminating toward the tip. The Bs is further divided into three subtypes: large basiconic sensilla $(Bs_1)$, small basiconic sensilla $(Bs_2)$ and spiniform basiconic sensilla $(Bs_3)$. The $Bs_1$ is located at the 5th and 6th articles, while the $Bs_2$ and $Bs_3$ can be seen at the 5th and at the 7th article, respectively.

• Applied Microscopy
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• v.39 no.2
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• pp.149-156
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• 2009

Fine structure of the dry adhesion system in the tarsal appendages of the jumping spider Plexippus setipes (Araneae: Salticidae) with examined using field emission scanning electron microscope (FESEM). The jumping spiders have the distinctive attachment apparatus for adhesion on smooth dry surface without sticky fluids. They attach to rough substrates using tarsal claws, however attachment on smooth surfaces is achieved by means of a tuft-like hair called a scopula. All eight legs have the scopulae with a pair of claws on the tip of feet, and each scopula is composed of two groups of setae that are capable of dry adhesion on smooth surface. The apex of each seta is flattened pad bearing many specialized adhesive setules on one side. The cuticular sensillae are interspersed at the dorsal surface of the seta. It has been revealed by this research that the contact area of the setule is always a triangular shape, and these cuticular surfaces are connected by the elongated stalks from the underlying setae. Moreover, adhesion between the numerous setules and the setae was prevented by the microscopic hairs, since these were interspersed on the upper side of the setae.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.106-115
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• 2010

The purpose of this study was to evaluate the microtensile bond strength (${\mu}TBS$), failure modes and bonding interfaces of self-etching and three self-adhesive resin cements to dentin and indirect composite resin. Cylindrical composite blocks (Tescera, Bisco Inc.) were luted with resin cements (PA: Panavia F 2.0, Kuraray Medical Inc., RE: RelyX Unicem Clicker, 3M ESPE., MA: Maxem, Kerr Co., BI: BisCem, Bisco Inc.) on the prepared occlusal dentin surfaces of 20 extracted molars. After storage in distilled water for 24 h, $1.0\;mm\;{\times}\;1.0\;mm$ composite-dentin beams were prepared. ${\mu}TBS$ was tested at a cross-head speed of 0.5 mm/min. Data were analyzed with one-way ANOVA and Tukey's HSD test. Dentin sides of all fractured specimens and interfaces of resin cements-dentin or resin cements-composite were examined at FESEM (Field Emission-Scanning Electron Microscope). In conclusion, PA and RE showed higher bond strength and closer adaptation than MA and BI when indirect composite blocks were luted to dentin using a self-etching and three self-adhesive resin cements.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.6
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• pp.888-895
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• 2015

For effective utilization of butter clam shell as a natural calcium resource, the optimal conditions for preparation of calcium acetate (BCCA) with high solubility were determined using response surface methodology (RSM). The polynomial models developed by RSM for pH, solubility, and yield were highly effective in describing the relationships between factors (P<0.05). Increased molar ratio of calcined powder (BCCP) from butter clam shell led to reduction of solubility, yield, color values, and overall quality. Critical values of multiple response optimization to independent variables were 2.70 M and 1.05 M for acetic acid and BCCP, respectively. The actual values (pH 7.04, 93.0% for solubility and 267.5% for yield) under optimization conditions were similar to predicted values. White indices of BCCAs were in the range of 89.7~93.3. Therefore, color value was improved by calcination and organic acid treatment. Buffering capacity of BCCAs was strong at pH 4.88 to 4.92 upon addition of ~2 mL of 1 N HCl. Calcium content and solubility of BCCAs were 20.7~22.8 g/100 g and 97.2~99.6%, respectively. The patterns of fourier transform infrared spectrometer and X-ray diffractometer analyses from BCCA were identified as calcium acetate monohydrate, and microstructure by field emission scanning electron microscope showed an irregular form.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.332-339
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• 2015

The objective of this study was to evaluate the effectiveness of different biochars on the removal of heavy metals from aqueous media. The experiment was carried out in aqueous solutions containing $200mg\;CdL^{-1}$ or $200mg\;PbL^{-1}$ using two different biochars derived from soybean stover and orange peel (20 mg Cd or $Pbg^{-1}$ biochar). After shaking for 24 hours, biochars were filtered out, and Cd and Pb in the filtrate were analyzed by flame atomic absorption spectrophotometer (FAAS). In order to provide information regarding metal binding strength on biochars, sequential extraction was performed by modified SM&T (formerly BCR). The results showed that 70~100% of initially added Cd and Pb was adsorbed on biochars and removed from aqueous solution. The removal rate of Pb (95%, 100%) was higher than that of Cd (70%, 91%). In the case of Cd, orange peel derived biochar (91%) showed higher adsorption rate than soybean stover derived biochar (70%). Cd was adsorbed on the biochar mainly in exchangeable and carbonates fraction (1st phase). In contrast, Pb was adsorbed on it mainly in the form of Fe-Mn oxides and residual fraction (2nd and 4th phase). The existence of Cd and Pb as a form of surface-precipitated complex was also observed on the surfaces of biochars detected by field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectrometer (EDAX).