• Resources Recycling
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• v.26 no.5
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• pp.54-60
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• 2017

In this study, we investigated the effect of $TiCl_4$ injection time on the Kroll reaction at a given weight ratio of $TiCl_4$ and Mg. The reduction reaction was investigated by measuring the temperature change according to $TiCl_4$ injection time and observing the cross section and appearance of the Ti sponge after the reaction. The temperature increment due to Kroll reaction heat generation was found to be linearly proportional to the $TiCl_4$ feed rate. In the graph of $TiCl_4$ injection time and reduction tank temperature, initial temperature peaks were observed irrespective of the injection conditions. This is interpreted to mean a temporary interruption of reaction due to $MgCl_2$ formation after the initial Kroll reaction. In addition, when the cross section of the sponge was observed, a large amount of spherical Mg particles was observed in $MgCl_2$. We can infer that this is the process of continuously feeding the unreacted Mg surface, so that a continuous Kroll reaction takes place. The sponge appearance showed that the coalescence or growth of the Kroll reacted Ti particles can be controlled by the cooling rate.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1353-1354
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• 2006

The dielectric properties of $Ba_{0.5}Sr_{0.5}TiO_3$(BST) and MgO-doped BST ceramics were investigated for tunable microwave applications by sol-gel method. The effects of MgO mixing with BST. It is observed that Mg substitution into BST causes a shift in the cubic-tetragonal BST Phase transition peak to a lower temperature. MgO-substituted BST and MgO-mixed phases exhibit homogeneous and broadened BST phase transition peaks. Mg substitution into BST has a significant effect on the grain sife reduction. Dielectric constant and loss is inhanced with decrease MgO dopant.

• Environmental Engineering Research
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• v.22 no.3
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• pp.281-287
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• 2017

The joint effect of different concentrations (0.05-0.375 mmol/L) of $Cd^{2+}$ and various concentrations (50-400 mg/L) of [$C_3mim$][OAc] on the growth and physiology of wheat seedlings were investigated. The toxicity of $Cd^{2+}$ could be significantly reduced by lower concentrations (50-200 mg/L) of [$C_3mim$][OAc]. With higher concentration (${\geq}300mg/L$) of [$C_3mim$][OAc], the reduction became less, and compared to $Cd^{2+}$ stress only, the toxicity of 400 mg/L [$C_3mim$][OAc] increased. As for different $Cd^{2+}$ concentrations, the optimal reduction depends on the balance between the exact concentration of $Cd^{2+}$ and [$C_3mim$][OAc]: With low $Cd^{2+}$ concentration (0.05-0.250 mmol/L) requiring 50 mg/L [$C_3mim$][OAc], it could reach a dynamic equilibrium, while high $Cd^{2+}$ concentration (0.375 mmol/L) requiring 100 mg/L [$C_3mim$][OAc]. The growth and physiological indexes of wheat seedlings show a decrease in toxicity compared to the Cd alone treatment, when the dynamic equilibrium is reached. The concentration of $Cd^{2+}$ in leaf tissues showed that low concentration (50-200 mg/L) of [$C_3mim$][OAc] can reduce the toxicity of $Cd^{2+}$ (0.05-0.375 mmol/L) by decreasing the level of $Cd^{2+}$ concentration in the tissues, whereas the higher concentration (${\geq}300mg/L$) of [$C_3mim$][OAc] can increase the concentration of $Cd^{2+}$.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.813-821
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• 2011

While various aspects affect river water quality, reduction of water flow rate during dry seasons is one of the most significant factors causing severe water pollution in river water environment. The aim of this study is to investigate the feasibility of applying a physicochemical method (sand filtration + ozonation) for improving river water quality within a short period. The parameters analyzed and assessed were $COD_{cr}$, BOD, SS and color. The source river water had a severe pollution level showing COD 8.8~17.2 mg/L (ave. 11.9 mg/L), BOD 4.8~13.3 mg/L (ave. 8.3 mg/L), SS 9.0~22.1 mg/L (ave. 12.8 mg/L) and color 34.4~77.1 degree (ave. 56.5 degree) during the experimental periods. The variation trends showed a relatively low correlation between BOD and COD and between color and COD, while SS showed very low correlation with other parameters. The combined process of sand filtration and ozonation showed averaged removal efficiency of COD 37.2%, BOD 48.4%, SS 60.1% and colority 45.1%, respectively. The marked change of BOD level from 8.3 mg/L to 4.3 mg/L under the experimental conditions in this study implied the improvement of class V to class III set by the river water quality standard in Korea.

• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.263-270
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• 2011

This study was performed to acquire processing and reducing factors of difenoconazole during ginseng processing, and to establish the maximum residue limits of ginseng and its commodities. Difenoconazole was used in two fields (Wonju and Icheon) containing 6 year old ginseng plants. The amount of residue at Wonju and Icheon were

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.232.1-232
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• 2003

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.19-22
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• 2014

The effects of Mg content on the pore formation, density and critical properties were investigated in in-situ reacted $MgB_2$ superconductors. The $Mg_{1+x}B_2$, (x=-0.2, 0.0, 0.05, 0.3, 1.0) bulk samples with different Mg contents were heat-treated at $900^{\circ}C$ for 1 h in an Ar atmosphere. The dimensional changes of a pellet's mass and volume after heat-treatment were measured. After heat-treatment process, the sample mass was decreased by Mg evaporation, but the sample volume was expanded by pore formation at the Mg site; therefore, the apparent density was decreased. Spherical pores the same as Mg particles were developed after heat-treatment in all samples, and the pore density was increased with increasing Mg content. As the x of Mg content was increased to 1.0, the apparent density of $Mg_{1+x}B_2$ samples was decreased due to a relatively larger reduction in a mass change. The critical current density of Mg excessive sample of x=0.05 showed the highest values over the applied magnetic fields because the excessive Mg may compensate Mg loss and enhance grain connectivity.

• Journal of Nutrition and Health
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• v.40 no.7
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• pp.630-638
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• 2007

This study was performed to examine the combined effects of L-carnitine and isoflavone supplementation on weight reduction and body fat distribution in overweight women. Overweight/obese women (body mass index > $23kg/m^2$) who were not diagnosed any type of diseases were included in this study and sixty subjects ($41.1{\pm}1.5$ years, $25.9{\pm}0.3kg/m^2)$ were randomly assigned to a placebo (n=30) or a supplement group (n=30, L-carnitine 300 mg+isoflavone 40 mg/day). We measured anthropometric parameters, abdominal fat distribution by computerizd tomography and blood components before and after the 12 week intervention period. After the 12 weeks of supplementation, subjects in L-carnitine and isoflavone supplement group showed a significant reduction of body weight (p < 0.001), body fat % (p < 0.05), and waist to hip ratio (p < 0.01) whereas placebo group did not show any changes. In a CT-scanned results, total fat area at L4 level was significantly reduced by 8.1% (p < 0.01) with the reduction of visceral fat area (-11.1%, p < 0.001) and subcutaneous fat area (-7.0%, p < 0.05) in the supplement group. The supplementation of L-carnitine and isoflavone showed the significant improvement of HDL-C (p < 0.01) and apoB (p < 0.05) concentrations, however, change values in those markers were not significant compared with those of the placebo group. In addition, a significant increase of adiponectin level (p<0.001) was observed in the supplement group after the intervention. The result of present study demonstrated that supplementation of 300 mg L-carnitine and 40 mg isoflavone per day fur 12 weeks can give beneficial effects on weight reduction and visceral fat accumulation. These potential antiobesity supplement can produce more favorable effects when combined with lifestyle modification.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.611-625
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• 2021

Mg crowns were manufactured using domestic dolomite (Ca·Mg(CO₃)₂) (20~30 mm). In order to manufacture the calcined dolomite (CaO·MgO), (a) electric furnace (950 ℃, 480 min) and (b) microwave furnace (950 ℃, 60 min) processes were used. As a result of XRD analysis, it was analyzed as (a) CaO 56.9 wt%, MgO 43.1 wt% by electric furnace process and (b) CaO 55 wt%, MgO 45 wt% by microwave furnace process. Even when the decarbonation reaction time of dolomite was shortened by 1/8 in microwave furnace process compare with electric furnace process, the calcined dolomite could be produced. The hydration reaction (ASTM C 110) is a standard for the hydration reactivity of calcined dolomite, and the calcined dolomite produced by electric furnace process showed a high hydration reactivity (max temp 79.8 ℃/1.5 minutes). Such hydration reactivity was occurred by only CaO hydration reaction and that was confirmed by XRD analysis. The calcined dolomite produced by microwave furnace process showed low hydration reactivity (max temp 81.7 ℃/19.5 minutes). Such low hydration reactivity was occurred by CaO and MgO hydration reaction due to the hydration reaction of CaO thereafter occurring of the hydration reaction of MgO, and that was confirmed by XRD analysis. The prepared Mg crown were 58.8 g and 74.6 g by electric furnace and microwave furnace processes, respectively, under the reaction conditions of 1,230 ℃, 60 min, 5 × 10^-2 torr by silicothermic reduction.

• Journal of Plant Biotechnology
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• v.40 no.4
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• pp.224-230
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• 2013

Lily is an important cut-flower in Korea and world as well due to it's a variety of flower colors and various sizes of flowers. To develop elite lily cultivars, conventional breeding techniques have been used so far. However, an introduction of tissue culture system in mass propagation of bulbs and regeneration of shoots with a high efficiency is prerequisite at this moment. Especially, growth of bulbs and shoots as well as reduction of browning is critical factor to proliferate bulbs with shoots of superior lines or cultivar in lily. For this purpose, we tried to test whether ascorbic acid, citric acid and silver nitrate in medium to facilitate growth of bulbs and shoots as well as reduction of browning of bulb scales in lily. As a result, ascorbic acid and silver nitrate showed no significant differences compared to control plants in the growth of bulbs and shoots. When bulb scales were treated with $150mg{\cdot}l^{-1}$ of citric acid, formations of shoots and bulbs showed best result. While, bulb scale treated with $100mg{\cdot}l^{-1}$ of citric acid showed the growth of shoot and root as well as increasing of fresh weight compared to other treatments. Regarding the reduction of browning, $150mg{\cdot}l^{-1}$ of ascorbic acid showed the best result with the less than 2%. Although more experiments with several commercial varieties are needed in the future to establish mass propagation of bulbs of lily, results obtained in this study are supposed to provide the basic knowledge and contribution in tissue culture system of lily.