• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.141-146
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• 2007

A new class of LC-resonator for micro magnetic sensor device was invented and fabricated by means of MEMS technique. The micro LC-resonator consists of a solenoidal micro-inductor with a bundle of soft magnetic microwire cores and a capacitor connected in parallel to the micro-inductor. The core magnetic material is a tiny glass coated $Co_{83.2}B_{3.3}Si_{5.9}Mn_{7.6}$ microwire fabricated by a glasscoated melt spinning technique. The core materials were annealed at various temperatures $150^{\circ}C,\;200^{\circ}C\;,250^{\circ}C\;,$ and $300^{\circ}C$ for 1 hour in a vacuum to improve soft magnetic properties. The solenoidal micro-inductors fabricated by MEMS technique were $500{\sim}1,000{\mu}m$ in length with $10{\sim}20$ turns. The changes of inductance as a function of external magnetic field in micro-inductors with properly annealed microwire cores were varied as much as 370%. Since the permeability of ultra soft magnetic microwire is changing rapidly as a function of external magnetic field. The inductance ratio as well as magnetoimpedance ratio (MIR) in a LC-resonator was varied drastically as a function of external magnetic field. The MIR curves can be tuned very precisely to obtain maximum sensitivity. A prototype magnetic sensor device consisting of the developed microinductors with a multivibrator circuit was test successfully.

• Food Science and Preservation
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• v.14 no.2
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• pp.207-212
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• 2007

The antimicrobial activity of Curcuma aromatica Salab. was investigated. The Curcuma aromatica Salab. extract showed antimicrobial activity against six pathogens tested. These were Listeria monocytogenes ATCC 19115, Pseudomonas fluorescens ATCC 21541,Staphylococcus aureus ATCC 29273, Salmonella typhimurium ATCC 21541, vibrio parahaemolyticus ATCC 17802, and Aeromonas hydrophila KCTC 2358. Antimicrobial activity was alsonoted when the extract was tested against four isolates of Bacillus sp. purified from spoiled tofu. The growth of various pathogens was significantly inhibited (100 10,000-fold) upon growth in tryptic soy broth containing 0.05 0.2%(w/v) Curcuma aromatica Salab. extract(CE), after incubation for 12hr at $37^{\circ}C$. The growth of the four Bacillus isolates was also significantly inhibited in nutrient broth containing 0.05 0.2% CE after incubation for 24hr at $37^{\circ}C$. Although the antimicrobial activity of CE was decreased by heat treatment at temperatures above $80^{\circ}C$, the activity remained relatively high after heat treatment at $121^{\circ}C$ for 15min. The minimum inhibitory concentrations of CE were 0.1 0.3%(v/v culture) for the six pathogens, and 0.2 0.25% for the Bacillus isolates, respectively.

• Food Science and Preservation
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• v.25 no.1
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• pp.155-163
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• 2018

The present study was carried out to investigate the physicochemical properties of hot water extracts of red ginseng powder prepared by two-stage hot air drying method using steamed ginseng and steaming liquid for 2.5 h under high-temperature and high-pressure autoclave condition. The total polyphenols, total flavonoids, total sugar, acid polysaccharides and crude saponin in hot water extracts from red ginseng powder were analyzed and determined, and the flavor components of ginseng were measured using color difference meter and an electronic tongue. The total polyphenol, total flavonoid, total polysaccharide, and acid polysaccharide of the red ginseng hot water extract obtained by autoclaving (ARG) were 9.06 mg GAE/g, 3.38 mg NE/g, 35.22 g/100 g, and 10.90 g/100 g, respectively. The final contents of the total polyphenols, total flavonoids, crude saponin were higher than those determined using other red ginseng methods; the time required for steamed red ginseng production reduced. The total ginsenoside content of ginseng including Rb1 was 10.69 mg/g, which is the lowest ARG. The processing conditions affected the conversion to ginsenosides unique to red ginseng. Red ginseng and steaming liquid obtained from the autoclave are expected to be in need for non-food materials and products as well as foods by improving the flavor components through conversion of red ginseng components into low molecular weight.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.652-656
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• 2018

In this study, effects of the reaction pressure were studied for petroleum-based pitch synthesis. A two-stage reaction process was performed based on different reaction pressure conditions. Each stage experiments for the two-stage reaction were consecutively carried out. The first stage was consisted of three different pressure conditions; high (10 bar), normal and low (0.1 bar). And the second stage was carried out at the normal and low (0.1 bar) pressure. The pitch synthesis was realized at $400^{\circ}C$ for 2 h. Thermal properties and molecular weight distributions of each samples were investigated by analyzing the softening point and MALDI-TOF data. Volatilized components during the pith synthesis were measured by GC-SIMDIS. In case of the first-step reaction with the high pressure condition, the low molecular weight component participated to the pitch formation more effectively and the pitch with the low softening point was obtained. However, for the case of the first-step with the low pressure, the low molecular weight component was vent outside and the partial coke formation occurred. Eventually, pitch properties such as the softening point and yield were controlled effectively by changing the pressure in the pitch synthesis reaction.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.553-558
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• 2019

In present study, the cylindrical susceptor by the slip casting method was designed to apply high-temperature induction heating by using $(Mo,W)Si_2$ ceramics. $MoSi_2$-based materials were synthesized by SHS (Self-propagating High-temperature Synthesis) method. The phase and crystal structure of $MoSi_2$-based materials were confirmed by XRD analysis. The shape of cylindrical mold was synthesized for various thickness by using the slip casting method. Finally, the susceptor for induction heating was processed by sintering and heat treatment to form $SiO_2$ layer, which was confirmed on the surface of susceptor by SEM/EDS analysis. To evaluate the heating performance of $(Mo,W)Si_2$ cylinder susceptor, we measured the maximum surface temperature and heating rate in comparison with the rod heating element under constantly applied power. The induction heating of the $(Mo,W)Si_2$ cylinder showed excellent heating performance, reaches the maximum temperature of $1457^{\circ}C$, with the average heating rate of $19^{\circ}C/s$ at 2 kW

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.14-18
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• 2019

The conductivity of a semiconductor is primarily determined by the carriers. To achieve higher conductivity, the number of carriers should be high, and an energy trap level is created so that the carriers can cross the forbidden zone with low energy. Carriers have a crystalline binding structure, and interfacial mismatching tends to make them less conductive. In general, high-concentration doping is typically used to increase mobility. However, higher conductivity is also observed in non-orthogonal conjugation structures. In this study, the phenomena of higher conductivity and higher mobility were observed with space charge limiting current due to tunneling phenomena, which are different from trapping phenomena. In an atypical structure, the number of carriers is low, the resistance is high, and the on/off characteristics of capacitances are improved, thus increasing the mobility. ZTO thin film improved the on/off characteristics of capacitances after heat treating at $150^{\circ}C$. In charging and discharging tests, there was a time difference in the charge and discharging shapes, there was no distinction between n and p type, and the bonding structure was amorphous, such as in the depletion layer. The amorphous bonding structure can be seen as a potential barrier, which is also a source of space charge limiting current and causes conduction as a result of tunneling. Thus, increased mobility was observed in the non-structured configuration, and the conductivity increased despite the reduction of carriers.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.1
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• pp.18-24
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• 2019

Isoflavones, a group of secondary metabolites present in plants and especially abundant in soybeans, are garnering increasing interest because of their medicinal properties. Numerous environmental factors influence isoflavone accumulation in plants. Successful attempts to increase isoflavone contents in soybean seeds have not been widely reported. In this report, we examined an effective method for producing a high amount of isoflavones during soybean seed germination, by treating the seed with 4 abiotic factors. Soybean seeds were exposed to ultrasound (50 Hz) and heat ($40^{\circ}C$) for 30minutes, then germinated for 5 days in darkness. Another sample was subjected to water deficit during germination in darkness, and the other sample was subjected to light conditions during the germination period. The results showed that the ultrasound treatment increased isoflavone content during soybean germination. Three days after germination, the ultrasound-treated seeds presented the highest isoflavone content (6,042.1 ug/g dry weight) compared to the other treatments, which was also 1.3-fold increases over the content of the raw seed's before germination. With respect to each type of isoflavone group, aglycone (partially genistein) content was markedly higher, whereas glucoside was lower than that of the untreated samples. In other experiment, total isoflavone content after heat, water deficit, and light treatments was 5,600.0, 4,740.1, and 5,631.4 ug/g, respectively. These present work suggests that ultrasound treatment is a novel approach for improving the production of isoflavones in soybean seeds during germination.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.485-492
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• 2018

About 300 thousand tones of oyster shells are produced annually and, thus, their massive recycling methods are required. Recently, a method, utilizing them as wet desulfurization materials after removal of organic matters and changing $CaCO_3$ phase into CaO through calcination, is under consideration. This study investigates the mineralogical changes (specific surface area, phase changes, surface state, etc.) of oyster shells by calcination and their characteristics were compared with those of limestone. Uncalcined oyster shells showed the higher specific surface area than limestone because the former are composed of platy and columnar structures. In contrast, investigated limestone showed a dense structure. The phase change of oyster shells occurred at lower temperature than that of limestone. The specific surface area of oyster shell decreased significantly after calcination while limestone depicted a drastic increase. Small amount of Na contained in oyster shell was suggested as the cause of this phenomenon; in that, it acted as a flux causing melting and sintering of oyster materials at lower temperature. Because of this, an additional phenomenon was observed that a part of shell materials remained untransformed even at higher calcination temperature and after longer treatment period due to the sintered surface, which covers the rest parts. Further studies investigating the effect of this phenomena from the perspective of desulfurization is required.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.668-675
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• 2019

Fine dust in air pollutants is recognized as one of the most serious social environmental problems. Most of the NOx is generated in a combustion process such as that of a coal-fired power plant, and therefore efficient elimination of the NOx from the coal-fired power plants is needed. This study investigates the removal efficiency of using $TiO_2$, a photocatalyst, to remove NOx by Selective Catalytic Reduction (SCR). To evaluate the NOx removal efficiency, $TiO_2$ catalyst and phosphate binder were mixed on the surface of the $Al_2O_3$ substrate with the exothermic agent, and the substrate was heat-treated. The NOx removal efficiency of the catalysts was evaluated according to the temperature, and XRD, SEM, TG-DTA and BET analyzes were performed to investigate the physicochemical properties of the catalysts. NOx removal efficiency was 58.7%~65.9% at 20min, 63.7~66.0% at 30min with temperature change according to time($250^{\circ}C{\sim}500^{\circ}C$). The $TiO_2$ used in the SCR for NOx removal is judged to have the most efficient removal efficiency at $300^{\circ}C$.

• Journal of Life Science
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• v.29 no.2
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• pp.158-163
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• 2019

The purpose of this study was to isolate a new marine agarase-producing bacterium. Agarase can hydrolyze agar and agarose to produce agarooligosaccharides or neoagarooligosaccharides, which possess many physiological functions. Strain DH-3 was isolated from seawater collected from the coast of Yeosu at Jeollanam province, Korea. A 16S rDNA sequence analysis showed this strain to be Persicobacter sp. DH-3. Extracellular agarase was prepared from culture media of Persicobacter sp. DH-3 and used for characterization. Relative activities at 20, 30, 40, 50, 60, and $70^{\circ}C$ were 50, 55, 70, 100, 90, and 50%, respectively. Relative activities at pH 5, 6, 7, and 8 were 75, 100, 90, and 75%, respectively. The enzyme showed maximum activity at $50^{\circ}C$ in a 20 mM Tris-HCl buffer at pH 6. This enzyme could be useful, as agar is in liquid state at $50^{\circ}C$. Agarase activities were maintained at 80% or more for 2 hr at 20, 30, and $40^{\circ}C$. Thin layer chromatography analysis suggested that Persicobacter sp. DH-3 produced extracellular ${\beta}$-agarases as it hydrolyzed agarose to produce neoagarohexaose and neoagarotetraose. In addition, zymogram analysis confirmed that Persicobacter sp. DH-3 produces at least three agar-degrading enzymes with molecular weights of 45, 70, and 140 kDa. Therefore, it is expected that agarases from Persicobacter sp. DH-3 could be used to produce functional neoagarooligosaccharides.