• Korean Journal of Plant Tissue Culture
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• v.24 no.5
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• pp.285-289
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• 1997

Leaf and stem explants of Sedum erythrostichum Miq. were cultured on MS medium supplemented with various combinations of growth regulators. After two weeks of culture, 100% of the leaf explants formed calli on medium containing 2.0 mg/L 2, 4-D and 1.0 mg/L BA. Callus proliferated when subcultured on medium containing 2.0 mg/L 2, 4-D and 1.0 mg/L BA. Numerous adventitious buds were regenerated from callus cultured on the medium containing 2.0 mg/L NAA and 1.0 mg/L BA. Root formation from shoot was occurred on the MS basal medium containing 1.0 mg/L IAA.

• Progress in Superconductivity and Cryogenics
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• v.22 no.4
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• pp.20-23
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• 2020

Among many variables in processing the high performance MgB2 bulk superconductors, simple and important approach is to optimize the size dependence of the Mg & B raw powders. The present study is dedicated towards the variation in superconducting properties of MgB2 depending upon the various combination of Mg & B powders with the two different particle sizes respectively. From morphological investigation of the MgB2 samples, narrow and long pores are observed when the larger Mg powders are used, whereas it is rather like the oval shapes with the smaller Mg powders. Also, it can be seen that the connectivity of the MgB2 samples is much enhanced with the smaller size of the B powders. Jc-H properties of the MgB2 samples also indicate that the highest Jc can be obtained when using the smaller size of the B powder with the combination of the smaller Mg powders than that of the larger Mg powders. If the cases with the larger B powers, it is more favorable to select the larger Mg powders with the better Jc-H properties considering shorter diffusion length of Mg and more homogeneous mixture between the Mg & B powders.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.144-149
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• 2000

Variables affecting the passivation capability of Cu(Mg) alloy films, which were sputter deposited from a Cu (4.5 at. %) target, have been investigated. The results show that the passivation capability of a Cu(Mg) alloy film is a function of annealing temperature, $O_2$ pressure, and Mg content in the film. Increasing the annealing temperature up to $500^{\circ}C$ favors formation of a dense MgO layer on the surface which has a growth limited thickness of 150 $\AA$. Decreasing the $O_2$ pressure enhances the preferential oxidation of Mg over Cu. Furthermore, increasing the Mg content in the Cu(Mg) film promotes formation of a dense MgO layer. Vacuum pre-annealing was found to be very effective in segregating Mg to the surface, facilitating the passivation capability of the Cu(Mg) alloy film even when the Mg content is low. In the current study, self-aligned MgO layers with low resistivity and an effective passivation capability over the Cu surface, have been obtained by manipulating these factors when Cu(Mg) thin films are annealed.

• Korean Journal of Weed Science
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• v.16 no.3
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• pp.221-229
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• 1996

This study was carried out to determine the effects of growth regulators, carbon sources and silver nitrate on callus formation and plant regeneration of turfgrass. The results were summarized as fallows : Callus from Korean lawngrass (Zoysia japonica Steud.) and pencross creeping bentgrass (Agrostis palustrir Huds.) induced better in MS medium than in N6 medium and by addition of 2,4-D than by that of NAA. Callus formation from Korean lawngrass and penncross creeping bentgrass was very effective at MS medium adding 1mg/L 2,4-D and at the medium adding 2mg/L 2,4-D, repectively. Growth of callus was good at MS medium containing 2mg/L 2,4-D+0.2mg/L NAA. Callus growth of Korean lawngrass and penncross creeping bentgrass was good when kinetin was added 0.2mg/L and 0.3mg/L, individually, to MS medium containg 2mg/L 2,4-D+0.2mg/L NAA. Regeneration rate from leaf and stock callus of Korean lawngrass was 44% at MS medium adding 2,4-D 2mg/L+NAA 0.2mg/L+kinetin 0.3mg/L and 32% at the medium containing 2,4-D 2mg/L+NAA 0.2mg/L+kinetin 0.3mg/L, each and that from leaf and stock callus of penncross creeping bentgrass was 80% and 67%, each, at the medium adding 2,4-D 2mg/l+NAA 0.2mg/L+kinetin 0.3mg/L. Regeneration rate of Korean lawngrass and penneross creeping bentgrass increased by 3 to 4% and by 10 to 16%, respectively, when added $AgNO_3$ 1~2mg/L to the above-mentioned regeneration medium.

• The Korean Journal of Nuclear Medicine
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• v.19 no.1
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• pp.127-136
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• 1985

To evaluate change of serum $beta_2-microglobulin$ concentration$(s\beta_2-MG)$ and the usefulness of $s\beta_2-MG$ and $s\beta_2-MG/serum$ creatinine concentration(sCr) ratio in various renal diseases, $s\beta_2-MG$ and sCr were measured in 25 normal controls and 90 patients of various renal diseases(16 cases of glomerulonephritis, 12 cases of acute renal failure, 8 cases of chronic renal failure, 24 cases of nephrotic syndrome, 15 cases of tubulointerstitial diseases and 15 cases of lupus nephritis) using $Phadebas^\circledR$ $Beta_2-Micro$ Test kits. The results were as follows; 1) In normal control, the mean value of $s\beta_2-MG$ was $1.65{\pm}0.41mg/l$ and the mean value of $s\beta_2-MG/sCr$ ratio was $0.14{\pm}0.05$. 2) In various renal diseases, the mean value of $s\beta_2-MG$ was $6.74{\pm}5.47mg/l$. The mean value of $s\beta_2-MG/sCr$ ratio was $0.24{\pm}0.11$ and significantly elevated than that of normal control. (p<0.05) 3) The correlation between $s\beta_2-MG$ and sCr in glomerular and tubulointerstitial disease was log $s\beta_2-MG-0.90$ log sCr-0.48 and its correlation coefficient was 0.78(p<0.05). 4) In glomerular disease, the correlation between $s\beta_2-MG$ and sCr was log $s\beta_2-MG-0.89$ log sCr-0.46(r - 0.76) and in tubulointerstitial disease, it was log, $s\beta2-MG-0.95$ log sCr-0.59 (r-0.87). There was no significant difference between the two groups(p<0.05). 5) Among 32 cases of glomerular and tubulointerstitial disease patients, whose sCr was within normal range, 17 cases showed elevated $s\beta_2-MG$. The mean values of $s\beta_2-MG/sCr$ ratio in these patients was $0.30{\pm}0.14$ and significantly elevated than that of normal control(p<0.05). 6) In 15 cases of lupus nephritis, 12 cases showed elevated $s\beta_2-MG$ with normal sCr and 12 cases showed elevated $s\beta_2-MG/sCr$ ratio. With above results, it was found that the $s\beta_2MG$ can be used as an index of glomerular filtration rate as in the case of sCr and that $s\beta_2-MG/sCr$ ratio can be used as a tool in early detection of slightly decreased glomerular filtration rate and in detection of the renal disease of increased $\beta_2-MG$ production.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.538-544
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• 1985

This study was carried cut to evaluate the water quality of spring waters in Pusan area(see Fig. 1). In this experiment, twenty-five water samples were collected from 5 stations from December 1983 to August 1984. Range and mean values of constituents of the samples are as follows: pH $5.80{\sim}7.25$, 6.60; water temperature $6.0{\sim}23.0^{\circ}C,\;12.9^{\circ}C$; total residue $33.0{\sim}325mg/l$, 121.2mg/l; alkalinity $4.75{\sim}51.6mg/l$, 24.1mg/l; hardness $9.47{\sim}85.0mg/l$, 30.3mg/l; electrical conductivity $0.495{\sim}2.750{\times}^2{mu}{\mho}/cm,\;1.239{\times}10^2{\mu}{\mho}/cm$;turbidity $0.54{\sim}7.80$NTU, 2.04NTU; $KMnO_4$ consumed $0.51{\sim}8.47mg/l$, 1.96mg/l; chloride ion $4.91{\sim}36.0mg/l$, 12.55mg/l; fluoride ion ND-0.30ppm, 0.08ppm; nitrate-nitrogen ND-8.94mg/l, 1.94m:g/l; nitrite-nirogen ND-0.10mg/l, 0.03mg/l; ammonia-nitrogen ND-0.16mg/l, 0.03mg/l: phosphate-phosphorus ND-0.09mg/l, 0.03mg/l; silicate-silicious $0.42{\sim}22.7ng/l$, 7.96mg/l; copper ND-10.5ppb, 2.46ppb; lead ND-22.7ppb, 3.54ppb; zinc ND-103ppb, 21.33ppb; iron $20.3{\sim}2,800ppb$, 801.72ppb, respectively. Arsenic, cyan, cadmium, manganese, mercury, chrome and phenol were not detected. Total residue, electrical conductivity, turbidity and chloride ion of station 1 (Milrakdong) were higher than others as 178.1mg/l, $2.127{\times}10^2{\mu}{\mho}/cm$, 3.16NTU and 16.32mg/l. The concentration of silicious had a great influence on precipitation. The concentration of fluoride ion of spring waters was lower as 0.08ppm than the criterion for drinking water as 1ppm, while iron was exceed 2.7 times as 801.72ppb.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.36-39
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• 2022

Since the MgB₂ superconductor is simply composed of two constituents of Mg and B, its performance can be monitored easily with the change of one ingredient compared to the other. With the powder size of B less than 100 nm, two different sizes of Mg powders are used to investigate the reaction temperature dependence of MgB₂ bulk samples. In the range of 630-700℃ for the duration of 30 min., the un-reacted Mg is seen only at 630℃ with Mg powder size of <5 ㎛, whereas Mg traces are detected at all the temperature range with Mg powder size of <45 ㎛. The reaction temperature dependence of MgB₂ superconducting transition temperature, T_c, shows little difference whether Mg powder size is large or small in this range except for the 630℃. It is worthy of notice that the critical current densities of MgB₂ show higher performance with the small size of Mg compared to the large one at all field ranges. With the Mg powder size of <45 ㎛, flux pinning is enhanced with decreasing the reaction temperature, whereas flux pinning properties is quite similar in the Mg powder size of <5 ㎛ except for the 630℃, where Mg is left behind after the reaction.

• Journal of Ceramic Processing Research
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• v.20 no.6
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• pp.609-616
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• 2019

The optimum powder to ball ratio was examined, which is one of the important conditions in reactive mechanical grinding processing. Yttria (Y2O3)-stabilized zirconia (ZrO2) (YSZ), Ni, and graphene were chosen as additives to enhance the hydriding and dehydriding rates of Mg. Samples with a composition of 92.5 wt% Mg + 2.5 wt% YSZ + 2.5 wt% Ni + 2.5 wt% graphene (designated as Mg-2.5YSZ-2.5Ni-2.5graphene) were prepared by grinding in hydrogen atmosphere. Mg-2.5YSZ-2.5Ni-2.5graphene had a high effective hydrogen-storage capacity of almost 7 wt% (6.85 wt%) at 623 K in 12 bar H2 at the second cycle (n = 2). Mg-2.5YSZ-2.5Ni-2.5graphene contained Mg2Ni phase after hydriding-dehydriding cycling. Mg-2.5YSZ-2.5Ni-2.5graphene had a larger quantity of hydrogen absorbed for 60 min, Ha (60 min), than Mg-2.5Ni-2.5graphene and Mg-2.5graphene. The addition of YSZ also increased the initial dehydriding rate and the quantity of hydrogen released for 60 min, Hd (60 min), compared with those of Mg-2.5Ni-2.5graphene. Y2O3-stabilized ZrO2, Ni, and graphene-added Mg had a higher initial hydriding rate and a larger Ha (60 min) than Fe2O3, MnO, or Ni and Fe2O3-added Mg at n = 1.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.939-944
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• 2012

The electrochemical behavior of magnesium ions was examined by cyclic voltammetry in a molten $MgCl_2-CaCl_2$-NaCl salt. The reduction potential of magnesium ions was measured and those values were estimated with the variation of the concentration of $MgCl_2$ and the temperature of molten salts. The diffusion coefficient of the $Mg^{2+}$ ions has been determined at 660, 680, 700, 720 and $740^{\circ}C$. The values were $8.79{\times}10^{-6}$, $9.56{\times}10^{-6}$, $1.17{\times}10^{-5}$, $1.4{\times}10^{-5}$ and $1.77{\times}10^{-5}\;cm^2\;s^{-1}$. The activation energy for the diffusion processes of $Mg^{2+}$ ions was found to be $70.28\;kJ\;mol^{-1}$ by using the Arrhenius equation.

• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.832-838
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• 1996

Thermite reaction products of MgO and Al were added to MgO-C refractory to improve the properties of corrosion against the attack of slag, oxidation and mechanical spalling. Corrosion rate of MgO-C-MgAl2O4 spinel refractory at the ratio of 3.3(CaO/SiO2) slag was smaller than that of MgO-C and MgO-C-Al refractory. The excellent corrosion resistance of the MgO-C-MgAl2O4 spinel refractory against the slag attack was appeared by Al and MgAl2O4 spinel with high melting point and corrosion resistance and the high thermal conductivity and low thermal expansion of AIN. Hot M.O.R at 140$0^{\circ}C$ and the resistance of oxidation weight loss at 90$0^{\circ}C$ were 210kg/cm2 and -12% respectively.