• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1661-1663
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• 2000

This study was to measure the dielectric characteristics of 0.05Pb($Al_{0.5}Nb_{0.5}$)-0.95Pb($Zr_{0.52}Ti_{0.48})O_3$[PAN-PZT] system ceramics according to the variation of $Cr_{2}O_3$, $Fe_{2}O_3$ addition amount. 0.0$\sim$1.2[wt%] and according to sintering temperature after creating the specimens with a general sintering way. The results of this study were summarized as follows : the dielectric constant at 20[$^{\circ}C$] reduced dy increasing additive on the whole. The dielectric loss was minimum value of 12.77[%], sintered at 1200[$^{\circ}C$], dopped with $Cr_{2}O_3$ 0.3[wt%] and minimum value of 10.89[%], sintered at 1200[$^{\circ}C$], dopped with $Fe_{2}O_3$ 0.6[wt%]. The variation rate of dielectric constant according to the change of frequency was decreased slowly by increasing frequency. The temperature coefficient of capacitance turned out increasing the stability of the temperature, decreased $Cr_{2}O_3$ 0.3wt% showed its minimum value 0.59[%/$^{\circ}C$], the maximum value 0.9[%/$^{\circ}C$] with $Cr_{2}O_3$ 3wt%.

• KSBB Journal
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• v.10 no.4
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• pp.441-448
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• 1995

Optimized fermentation medium and cultural conditions for the production or exopolysaccharide KS-1 with Bacillus polymyxa KS-1 was following as; 30g g1ucose, 2.59g yeast extract, $2.5g KH_2PO_4, 0.5g NaCl, 0.3g MgSO_4.7H_20, 0.1g CaC0_3 0.05g, FeSO_4.7H_2O, and 0.05g MnS0_4 . 4H_20in 1 liter distilled water. The exopolysaccharide production was influenced by the by the temperature and pH, the optimal conditions for the production of exopolysaccharide KS-1 seemed to be $30^{\circ}C$ and pH 7.0, respectively. About $10.3g/\ell$ of maximum exopolysaccharide was obtained al the initial pH 7.0, $30^{\circ}C$, 2vvm of aeration rate and 400 rpm of impeller speed in a jar fermentor.

• The Korean Journal of Community Living Science
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• v.22 no.4
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• pp.509-518
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• 2011

This study was intended to investigate dietary behavior, health related behavior and the effects of nutrient intake of female college students. Dietary behavior, health related behavior and the perception of the body conditions were surveyed with anonymous questionnaires, and 24hrs recall method for nutrient intake was obtained from 161 female college students in Chungbuk area. The mean height and weight of the subjects were $161.4{\pm}5.0$cm and $53.8{\pm}7.4 $kg, respectively. The dietary behavior of female college students was generally inadequate. More specifically, irregularity of meals, indifference of dietary balance, and skipping breakfast, showing $4.77{\pm}2.20$for dietary behavior score, $11.76{\pm}3.89$ for DVS and $3.58{\pm}0.82$ for DDS, respectively. It was found that almost 63% of subjects did not anything for health care and the frequency of exercise of subjects was low. The perception of body conditions of the subjects seemed to be generally positive. However, satisfaction levels on body shape was very negative showing that only 12.4% of subjects answered as 'very satisfied' and 'satisfied'. When nutrient intake of the female college students was compared with Dietary Reference Intake for Korean, folate(45%), potassium(55%), vitamin C(59%), Ca(72%), fiber(72%), Fe(79%) and energy(80%) were found to be insufficient. But protein(138%), P(122%) and Na(179%) were found to be oversupplied. The nutrient intake of fiber, plant Ca, vitamin A, ${\beta}$-carotene, vitamin B6, vitamin C, folate and vitamin E were significantly higher, and those of Fe, Zn and protein were a little high in the high score group of dietary behavior. Also Food group intake, DDS and DVS were higher in the high score group of dietary behavior.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.59-64
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• 2013

Effects of weathering intensity on the adsorption of heavy metals such as lead(Pb) and copper(Cu) onto decomposed granite soils were investigated by a series of batch tests. The chemical components such as $SiO_2$, $K_2O$ and $Na_2O$ having relatively high solubility were reduced and the oxidized $Fe_2O_3$ content was increased with the increase of weathering intensity. Weathering of granite soils increased the ignition loss and specific surface area, while it decreased the permeability. The lead and copper adsorptions onto the decomposed granites were enhanced with the increase of weathering intensity, mainly due to the increase of specific surface area and clayed contents. Adsorption of lead and copper onto the weathered granites could be more adequately described by the pseudo-second-order kinetic model than the pseudo-first-order model.

• Clean Technology
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• v.29 no.4
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• pp.288-296
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• 2023

Coal is abundantly available compared to other energy sources and is used as a versatile energy resource worldwide. To address the environmental issues stemming from conventional coal utilization, efforts are underway to develop clean coal utilization technologies, with IGCC technology being a notable example. In IGCC plants, coal is subjected to a CMD process where both drying and pulverization are achieved by supplying hot air. However, if the temperature of the supplied hot air is excessively high, it can lead to devolatilization and spontaneous combustion, thereby compromising the stable operation of the CMD process. This study aimed to measure the devolatilization and spontaneous combustion temperatures of different types of bituminous coal, and to explore their correlations with the characteristics of the coals. Six coal types exhibited devolatilization between 350 and 400 ℃, while three coal types showed devolatilization at temperatures exceeding 400 ℃. Spontaneous combustion ℃curred in one coal type below 100 ℃, six coal types between 100 and 150 ℃, and two coal types above 150 ℃. The measured initiation temperatures were compared with the coal characteristics including the oxygen, moisture, Fe₂O₃, and CaO content, the H/C ratio, and the O/C ratio to establish correlations. Regression analysis was used to calculate the regression coefficients and determination coefficients for each ignition temperature. It was found that 52.44% of the FC/VM data significantly influenced the volatile matter ignition temperature, and 59.10% of the Fe₂O₃ data significantly affected the spontaneous combustionignition temperature.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.743-748
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• 2010

Boron nitride (BN) and carbon nitride (CN) films, which have relatively low work functions and commonly exhibit negative electron affinity behaviors, were coated on carbon nanotubes (CNTs) by magnetron sputtering. The CNTs were directly grown on metal-tip (tungsten, approximately 500nm in diameter at the summit part) substrates by inductively coupled plasma-chemical vapor deposition (ICP-CVD). The variations in the morphology and microstructure of CNTs due to coating of the BN and CN films were analyzed by field-emission scanning electron microscopy (FE-SEM). The energy dispersive x-ray (EDX) spectroscopy and Raman spectroscopy were used to identify the existence of the coated layers (CN and BN) on CNTs. The electron-emission properties of the BN-coated and CN-coated CNT-emitters were characterized using a high-vacuum field emission measurement system, in terms of their maximum emission currents ($I_{max}$) at 1kV and turn-on voltage ($V_{on}$) for approaching $1{\mu}A$. The results showed that the $I_{max}$ current was significantly increased and the $V_{on}$ voltage were remarkably reduced by the coating of CN or BN films. The measured values of $I_{max}-V_{on}$ were as follows; $176{\mu}A$-500V for the 5nm CN-coated emitter and $289{\mu}A$-540V for the 2nm BN-coated emitter, respectively, while the $I_{max}-V_{on}$ of the as-grown (i.e., uncoated) emitter was $134{\mu}A$-620V. In addition, the CNT emitters coated with thin CN or BN films also showed much better long-term (up to 25h) stability behaviors in electron emission, as compared with the conventional CNT emitter.

• The Korea Journal of Herbology
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• v.30 no.4
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• pp.1-9
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• 2015

Objectives : The present study was under taken to characterize chemical composition, antioxidant and cyto-protecting capacity of essential oil obtained from leaves of Liriodendron tulipifera L. Methods : Essential oil from the leafof L. tulipifera L. (EOLL) was extracted by hydro-distillation process and further its chemical composition was evaluated by GC-MS analysis. The in vitro antioxidant potential of the EOLL was determined by DPPH ^●, ABTS ^●+, superoxide and nitric oxide free radical scavenging activity using different concentrations in the range of 50-800 μg/mL. In addition, cyto-protecting property of the EOLLwas determined by MTT assay on Raw 264.7 macrophage cells challenged with hydrogen peroxide (H ₂ O ₂ ). Results : The result of GC-MS analysis showed presence of 34 volatile compounds, principally germacrene D, spathulenol, and α -cadinol in EOLL. The in vitro antioxidant assays of EOLL at the highest used concentration of 800 μg/mL showed 81.62, 84.29, 83.59 and 58.59% inhibition of DPPH ^●, ABTS ^●+, superoxide, and nitric oxide radicals, respectively. It also showed ferric reducing ability with 1310.04 mM Fe (II)/g of essential oil. The EOLL at three different concentrations (200, 400 and 800 μg/mL) protected the cells from H ₂ O ₂ -induced cell damage through scavenging intracellular ROS. Conclusion : The findings from the study suggest that essential oil isolated from leaves of L tulipifera L. is a potent sources of natural antioxidants, which could be used to treat the diseases associated with oxidative stress condition.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.44 no.2
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• pp.59-65
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• 2018

Objectives: This study aimed to optimize the thread depth and pitch of a recently designed dental implant to provide uniform stress distribution by means of a response surface optimization method available in finite element (FE) software. The sensitivity of simulation to different mechanical parameters was also evaluated. Materials and Methods: A three-dimensional model of a tapered dental implant with micro-threads in the upper area and V-shaped threads in the rest of the body was modeled and analyzed using finite element analysis (FEA). An axial load of 100 N was applied to the top of the implants. The model was optimized for thread depth and pitch to determine the optimal stress distribution. In this analysis, micro-threads had 0.25 to 0.3 mm depth and 0.27 to 0.33 mm pitch, and V-shaped threads had 0.405 to 0.495 mm depth and 0.66 to 0.8 mm pitch. Results: The optimized depth and pitch were 0.307 and 0.286 mm for micro-threads and 0.405 and 0.808 mm for V-shaped threads, respectively. In this design, the most effective parameters on stress distribution were the depth and pitch of the micro-threads based on sensitivity analysis results. Conclusion: Based on the results of this study, the optimal implant design has micro-threads with 0.307 and 0.286 mm depth and pitch, respectively, in the upper area and V-shaped threads with 0.405 and 0.808 mm depth and pitch in the rest of the body. These results indicate that micro-thread parameters have a greater effect on stress and strain values.

• Journal of the Korean Home Economics Association
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• v.38 no.12
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• pp.59-71
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• 2000

The purpose of this study was to assess the iron nutritional status and dietary iron availability of postmenopausal women residing in Jeonju area. The anthropometric parameters, nutrient intake and biochemical status of iron were measured from 57 postmenopausal women aged 50∼74 years old. Mean values of hemoglobin(Hb), hematocrit(Hct), serum iron(Fe), total iron binding capacity(TIBC) and serum ferritin(Ferritin) concentration were 12.82${\pm}$1.03g/dl, 37.68${\pm}$2.99%, 92.60${\pm}$46.66ug/dl, 353.0${\pm}$54.48ug/dl, 86.86${\pm}$100.7ug/ιrespectively. Prevalence of iron deficiency greatly varied by indices from 14.04% when judged by Ferritin(<20ug/ι) to 40.4% by TIBC(>360${\mu}$g/dl. The anemic subjects assessed with Hct percent(36%) represented 22.8%, whereas 21.1% of the subjects possessed less than 12g/dl of Hb. Ferritin concentration showed a significantly negative correlation with TIBC(r=-0.343, p<0.01) and a positive correlation with MCHC(r=0.361, p<0.01). The mean daily intake of iron was 10.62mg and intake of heme iron was 5.3%(0.56mg) of total iron intake. Total absorbable iron caculated by the method of Monsen was 0.49mg anti bioavailability of dietary iron was 4.61%. Ferritin Concentration was positively associated with total iron intake(r=0.264, p<0.05), dietary nonheme iron(r=0.286, p<0.05) and iron of animal food (r=0.364, p<0.01). But Ferritin concentration was not correlated dietary heme iron(r=-0.137, p>0.05). Major food groups of iron intake were vegetables(20.15%), cereals(19.59%) and fishes(12.34%) in postmenopausal women. Intake of eggs was positively associated with Ferritin(r=0.473, p<0.01).

• Resources Recycling
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• v.28 no.3
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• pp.59-67
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• 2019

This study was conducted to fabrication pig iron containing copper and to reduce sulfur content pig iron. Roasting test was conducted for 1 ~ 9 hours at each temperature of $500^{\circ}C$, $700^{\circ}C$, and $900^{\circ}C$. In addition, the effect of oxygen partial pressure with 0.5, 0.8, and 1 atm was carried out for 30 minutes at $900^{\circ}C$. It was found that there is no effect to reduce sulfure in pig iron through roasting and oxygen partial pressures. The addition of CaO with 15 wt.% was found to reduce sulfur content up to 0.001 wt.%. The suitable temperature and reactive time for carbothermic reduction were $1600^{\circ}C$ and 30 minutes which shows the highest recovery rate of iron from the copper slag.