• Resources Recycling
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• v.22 no.1
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• pp.42-47
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• 2013

Ferro-Nickel slag is a byproduct of Ferro-Nickel manufacturing process. Ferro-Nickel slag mostly discarded or used as aggregates despite having useful ingredients such as magnesium oxide and silicon oxide. This study tried to extract process for Mg ion using $H_2SO_4$ solution. And remove impurities and get high purity $Mg(OH)_2$ using NaOH. Mg ion was extracted with the Fe ion and other Ferro-Nickel slag composition by $H_2SO_4$ solution. It is important to control the pH because remove impurities and obtain high-purity $Mg(OH)_2$. The impurities were removed by precipitation of the hydroxides. After this process, we added NaOH and high-purity $Mg(OH)_2$ was obtained.

• Progress in Superconductivity and Cryogenics
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• v.19 no.2
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• pp.19-24
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• 2017

Cryogenic milling which is a combined process of low-temperature treatment and mechanical milling was applied to fabricate high critical current density $(J_c)MgB_2$ bulk superconductors. Liquid nitrogen was used as a coolant, and no solvent or lubricant was used. Spherical Mg ($6-12{\mu}m$, 99.9 % purity) and plate-like B powder (${\sim}1{\mu}m$, 97 % purity) were milled simultaneously for various time periods (0, 2, 4, 6 h) at a rotating speed of 500 rpm using $ZrO_2$ balls. The (Mg+2B) powders milled were pressed into pellets and heat-treated at $700^{\circ}C$ for 1 h in flowing argon. The use of cryomilled powders as raw materials promoted the formation reaction of superconducting $MgB_2$, reduced the grain size of $MgB_2$, and suppressed the formation of impurity MgO. The superconducting critical temperature ($T_c$) of $MgB_2$ was not influenced as the milling time (t) increased up to 6 h. Meanwhile, the critical current density ($J_c$) of $MgB_2$ increased significantly when t increased to 4 h. When t increased further to 6 h, however, $J_c$ decreased. The $J_c$ enhancement of $MgB_2$ by cryogenic milling is attributed to the formation of the fine grain $MgB_2$ and a suppression of the MgO formation.

• Horticultural Science & Technology
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• v.16 no.2
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• pp.239-241
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• 1998

The experiments were carried out to improve culture efficiency of rhizome and mericlone propagation through settlement of problems occurring during culture period of temperate Cymbidium species. Shooting efficiency from rhizome of C. forrestii 'Nokwoon' was improved, when cultured in $H_3P_4$ medium (Hyponex 3+peptone 4g/L) supplemented with 170mg/L $NaH_2PO_4{\cdot}H_2O$ and 0.4mg/L Thiamin e HCl, but the other varieties were not influenced to shooting efficiency by additives. Medium in which rhizome of C. nishiuchianum 'Hodukjiwha' was cultured became less browned in $H_3P_4$ medium added with 150mg/L PVP, but the other treatments of antioxidants was failed to prevent the medium browning. Re-formation of rhizome from young shoots of C. forrestii 'Sojub', 5.5cm in length occured in $H_3P_4$ enriched with 2.0 mg/L NAA and 1.0 mg/L BA under darkness, but axillary buds were elongated in the medium with 1.0 mg/L NAA and 3.0 mg/L BA under light condition. On the other hand, rhizomes from young shoot of C. forrestii 'Seosinmae' and 'Songmae', 5.5cm and 2.5cm in length respectively were reformed in 2.0 mg/L NAA and 5.0mg/L kinetin under darkness, but multishoot from young shoot were emerged in 2.0mg/L NAA and 3.0mg/L BA.

• Journal of the Korean Ceramic Society
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• v.33 no.3
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• pp.299-306
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• 1996

We invesgated the fesibility of thin films deposition by pyrolysis of metalorganic precursors using chemical beam deposition (CBD) process. We attempted to understand the effects of deposition variables such as substrate temperature operating pressure effusion cell temperature and H2 partial pressure on the properties of MgF2 grown by CBD. Mg(tfac)2 was used as a precursor. MgF2 thin films were always grown in an amorphous state and crystallized bypost-annealing. he higher the substrate temperature and the lower the operating pressure the less the impurities I the deposited MgF2 thin films. H2 gas has to be supplied for the pyrolitic reaction of Mg(tfac)2 decomposition. MgF2 films annealed in H2 have lower C impurity than those annealed in O2. But their crysatllinity was independent of annealing atmosphere. The optimum conditions for the prepara-tion of MgF2 films by CBD process were as following : The substrate temperature 55$0^{\circ}C$ the operating pressure 10-4 torr; effusion cell temperature 21$0^{\circ}C$ the percentage of H2 100% Post-annealing in H2 gas was required to remove residual carbon and to form MgF2 crystalline phase.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.556-562
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• 2005

This study was performed to evaluate effects of pH and heavy metals on soil pollution in 167 sites of Gangwon-do. The overall pH range of soils was 4.3~8.4 The average soil pollution of Cd was 0.089 mg/kg (0.000~3.493 mg/kg), Cu 3.093 mg/kg (0.078~60.263 mg/kg), Pb 4.74 mg/kg (0.01~38.08 mg/kg), Hg 0.054 mg/kg (0.002~1.050 mg/kg), and As 0.971 mg/kg (0.031~77.051 mg/kg), but $Cr^{6+}$ was not detected in these soils. The average concentration of heavy metals in these soils was acceptable under the preliminary standard of soil preservation acts in Korea.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.929-932
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• 2004

It is known that small amount of MgO in excess is often added to develop pure perovskite single phase of PMN-based composite, however, extra MgO precipitates in grains and inhibits densification of PMN. In this study PMN-PT-BT (PBT) powder was prepared by a conventional mixed oxide method using $(MgCO_3)_4{\cdot}Mg(OH)_2{\cdot}5H_{2}O$ instead of MgO. The precursor was heated at $500^{\circ}C/1h$ and its surface was modified with MgO sol. This effect was investigated in the aspects of sintering and dielectric properties. Small amount of added MgO sol ($0.5{\sim}1.0wt\%$) enhanced sintering substantially below $1000^{\circ}C$. The PBT with $0.5wt\%$ MgO sol sintered at $900^{\circ}C/2h$ had density of $7.62\;g/cm^3$, room temperature dielectric constant of 14800, loss of dielectric constant of $1.1\%$, which were comparable to those of the PBT sintered at $1000^{\circ}C/2h$. It was noticeable that the extra MgO precipitated mostly on triple points and grain boundaries and resulted in inhibition of grain growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.2
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• pp.111-116
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• 1991

The effective p.eduction of 5'-GMP(5'-Guanylic acid) by enzymatic conversion of 5'-XMP(5'-Xanthyic acid) was investigated. The Iyophilized Brevibacterium ammoniagenes ATCC 19216 which were used as the XHP aminase source, was immobilized by entrapping in K-carrageenan, agar, polyacrylamide or Ca-alginate. $3\%$ K-carrageenan was selected as the most suitable matrix. In the production of 5'-GMP using the free cells of 3. ammoniagenes ATCC 19216, the optimum conditions were $42^{\circ}C$, PH 7.0, 100mg/ml glucose, 120mg/ml cell ,8mg/ml $MgSO_4\cdot7H_2O$, 5mg/ml POESA, 5mg/ml phytic acid. Under the conditions, $94.5\%$ of 5'-GMP was converted within 8 hours. In the production of 5'-GMP using the immobilized whole cells of B. ammoniagenes ATCC 19216, the optimum conditions were $37^{\circ}C$, pH 7.5, 50mg/ml glucose, 1mg/ml $KH_2PO_4$, 10mg/ml phytic acid, 60mg/ml cell, 8mg/ml $MgSO_4\;\cdot\;7H_2O$, 5mg/ml POESA. Under the conditions, $64.7\%$ of 5'-GMP was converted within 40 hours.

• Applied Biological Chemistry
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• v.44 no.2
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• pp.67-72
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• 2001

$H^+-ATPase$ located on plasma and vacuolar membranes play major roles in various cellular physiological processes. In order to investigate the physiological roles of $H^+-ATPase$, microsomes were prepared from tomato roots and the effects of various anions were measured on the activities of $H^+-ATPase$. $H^+-ATPase$ was inhibited by various anions. Citrate and phosphate were chosen to investigate detailed inhibitory mechanisms on $H^+-ATPase$ since they showed different levels of inhibition. Inhibitory effect of citrate was observed at the concentrations above 3 mM. When 20 mM citrate was added, the ATPase activity was decreased by 50-60%. However, the inhibitory effect of citrate was decreased by increasing the concentration of$Mg^{2+}$ The citrate-induced inhibited activity was recovered by the addition of $Mg^{2+}$ Addition of 7 mM $Mg^{2+}$ completely removed the inhibitory effect of citrate and the activity recovered to the level of the control experiment. These results imply that citrate chelates $Mg^{2+}$ and thus inhibits $H^+-ATPase$. Meanwhile, the inhibitory effect of phosphate was observed at the concentration above 3 mM and the activity was decreased by 50% in the presence of 30 mM phosphate. Further addition of $Mg^{2+}$ showed no recovery on the activity. These results imply that the inhibitory effect of phosphate is not dependent upon the concentration of $Mg^{2+}$.

• Resources Recycling
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• v.10 no.5
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• pp.16-21
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• 2001

Ultrafine $Mg(OH)l_2$and MgO powders were recovered from the waste solution containing $Mg^{++}$ which was a by-product of SHS (Self-propagating High temperature Synthesis)process. The optimum experimental conditions to prepare $Mg(OH)_2$were 13.0 of pH and 0.7M of $Mg^{++}$ content with addition of 9M of KOH as a pH regulator in acid leaching solution. Complete pre-cipitation of Mg(OH)$_2$from $Mg^{++}$ was realized at that condition. The dehydration reaction of the prepared Mg(OH)$_2$was studied by DSC, and the result was used for calcination process. In order to obtain MgO powder, dried Mg(OH)2 powder was calcined at $400~450^{\circ}C$. Particle size and shape of the prepared $Mg(OH)_2$and MgO powder was similar to those of the commercial powders.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.80-80
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• 2018

Hosta is a genus of the family Asparagaceae and distributed in East Asia. There are six Hosta species (Hosta capitata (Koidz.) Nakai, H. clausa Nakai, H. jonesii M.G.Chung, H. minor (Baker) Nakai, H. venusta F.Maek., and H. yingeri S.B.Jones) native to Korea and among them, four species (H. minor, H. jonesii, H. venusta and H. yingeri) are endemic to the Korea peninsula. Hosta is generally propagated by seed, crown division or tissue culture. However, tissue culture is a more efficient method to mass proliferation, a new cultivar development and disease-free plantlet production in a limit time. Hence, we conducted this study to evaluate the influence of various plant growth regulators (PGRs) treatments on the induction of callus and somatic embryo of the six Hosta species. Leaf, petiole and root were used to select optimum tissue culture explants. Petiole explants thus only were used for callus induction and somatic embryogenesis with TDZ (0.1, 0.5 or 1.0mg/L) and NAA (0.1 or 0.5 mg/L) combinations. After 12 weeks of culture, the highest rate of somatic embryogenesis was achieved on modificated MS medium containing 1.0 mg/L TDZ and 0.1 mg/L NAA in H. capitata and H. minor (15.5%, respectively), 0.1 or 0.5 mg/L TDZ and 0.1 mg/L NAA in H. jonesii (22.2%), 1.0 mg/L TDZ and 0.5 mg/L NAA in H. yingeri (26.7%), and 0.1 mg/L TDZ and 0.5 mg/L NAA in H. venusta (53.3%). H. clausa showed very low effect on somatic embryogenesis by PGRs; 2.2%. There was interspecies difference to PGRs respond for callus and somatic embryo induction. Regenerated multiple shoots and plantlet of H. minor, H. jonesii, H. venusta and H. yingeri were obtained via somatic embryogenesis.