• Journal of Korean Society of Forest Science
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• v.97 no.3
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• pp.266-273
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• 2008

The effects of soil acidification on the seedling growth and nutrition of Pinus densiflora and Quercus acutissima were investigated. The relationship between the seedling growth and molar (Ca+Mg+K)/Al ratio of in soil solution was examined. The results suggested that growth inhibition of seedling Pinus densiflora and Quercus acutissima was due to the low pH of soil solution, which was followed by leach of Al into soil solution, and decrease of essential elements, such as Ca in aerial pant of the seeding caused by the increase of Al concentration in subterranean pant of the seedlings. The level of growth inhibition was determined not only by Al concentration, but also by the balance of inorganic elements, Al, Ca, Mg and K. The growths of two species in total dry weight were clearly inhibited when molar (Ca+Mg+K)/Al ratio of the soil was lower than 6.0. The growth in dry weight, in the condition of the molar ratio was 0.8, was decreased 60% or 50% for the seedling of Pinus densiflora or Quercus acutissima respectively. It was concluded that the molar (Ca+Mg+K)/ Al ratio could be an important index for evaluation of the effects of soil acidification, due to acid deposition such as acid rain, on growth of trees and nutrition. And it might be a more useful indicator for evaluation of critical load of acid deposition on forest ecosystems.

• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.611-619
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• 1998

This study was carried out to examine the effects of soil acidification on growth and nutrient status of 2 - year - old Pious densiflora Sieb. et Zucc. seedlings grown for 120 days in brown forest soils acidified with $H_2SO_4$ solution with or without leaching rations from the soil. The concentrations of A1 in the acidified soils increased with increasing amount of $H^+$ added to the soil. The total dry weight of the seedlings was decreased by the addition of the $H_2SO_4$ solution. The increase of Al concentration in the belowground part resulted from the decreased concentration of essential mineral elements such as Ca and Mg in the aboveground part. In addition, a strong positive correlation(r=0.96, p<0.001) was observed between the dry weight of the seedlings and the molar (Ca+Mg+K)/A1 ratio of the soil solution. When the molar (Ca+Mg+K)/Al ratio was approximately 7.0, the dry weight of the seedlings began to decrease compared with that of the seedlings in the control treatment. The seedlings with the molar (Ca+Mg+K)/Al ratio of 1.0 resulted from approximately 40% growth reduction compared with the control value. The results suggest that the molar (Ca+Mg+K)/Al ratio of the soil solution may be a useful indicator for assessing the critical load of acid deposition.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.298-302
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• 2012

Fe/$SiO_2$ core-shell type composite nanoparticles have been synthesized using a reverse micelle process combined with metal alkoxide hydrolysis and condensation. Nano-sized $SiO_2$ composite particles with a core-shell structure were prepared by arrested precipitation of Fe clusters in reverse micelles, followed by hydrolysis and condensation of organometallic precursors in micro-emulsion matrices. Microstructural and chemical analyses of Fe/$SiO_2$ core-shell type composite nanoparticles were carried out by TEM and EDS. The size of the particles and the thickness of the coating could be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of TEOS within the micro-emulsion. The water/surfactant molar ratio influenced the Fe particle distribution of the core-shell composite particles, and the distribution of Fe particles was broadened as R increased. The particle size of Fe increased linearly with increasing $FeNO_3$ solution concentration. The average size of the cluster was found to depend on the micelle size, the nature of the solvent, and the concentration of the reagent. The average size of synthesized Fe/$SiO_2$ core-shell type composite nanoparticles was in a range of 10-30 nm and Fe particles were 1.5-7 nm in size. The effects of synthesis parameters, such as the molar ratio of water to TEOS and the molar ratio of water to surfactant, are discussed.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.675-694
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• 2000

The purpose of this study was to investigate the displacement of and the stress distribution on the prosthesis, abutment, and its supporting tissues under functional load, and the effect of alteration in root length of 2nd abutment. The 3-dimensional finite element method was used and the finite element models were prepared in which the abutments of left mandibular 5 unit axed partial denture were canine, the 1st pre-molar and the 2nd molar, and the root lengths of canines were as follows. Model I : Root length of canine was 2mm longer than the 1st premolar Model II : Root length of canine was 2mm shorter than the 1st premolar Static compressive force of 300N was applied to connector between 2nd premolar & 1st molar, and then von Mises stress, displacement and reaction force were obtained. The results were as follows : 1. In fixed partial denture, prosthesis under load on pontic was rotated around mesio-distal long axis of it from longual side to buccal, and simultaneously bended in buccal and gingival direction with mesial end deformed in gingival direction and distolingual end in occlusal. 2. Clinical crowns of abutments were bended in the same directions with those in which prosthesis deforms. Due to that, roots of anterior abutments were twisted in counterclockwise with concentration of shear stress on distal or distobuccal sides of their cervices, and that of posterior was in clockwise with concentration of shear stress on mesiobuccal side of it in the same level with anterior abutments. 3. In case that root length of the 2nd abutment was longer than that of the 1st abutment, its displacement and reaction force which means the force tooth exerts on the surrounding periodontal tissues were smaller but shear stress on itself was larger than in the case root length of 2nd abutment was shorter.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.327-334
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• 2018

Water-repellent coating solutions were prepared by sol-gel method using tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as precursors. The solutions were spin-coated on a cold-rolled steel sheet and thermally cured to prepare a non-fluorine water-repellent coating films. The effects of molar ratios of MTMS/TEOS, water concentration and ammonia concentration on the hydrophobic properties of the coating films were studied. The contact angle of water on coating films prepared by varying the molar ratio of MTMS/TEOS to 1~20 showed a maximum value of $108^{\circ}$ when the MTMS/TEOS molar ratio was 10. With increasing water content, the coating films showed the larger contact angles and the better the water repellency. As the amount of ammonia added was increased, the contact angles of coating films were increased, showing the better the water repellency. It is considered that the larger the amount of ammonia added, the larger the size of the silica particles generated, which increases the surface roughness of the silica particles, thereby increasing the water repellency.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.589-593
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• 2002

The single crystalline thick fi1ms of Bi:Y$_3$Fe$_{5}$ $O_{12}$(Bi:YIG) were grown on (GdCa)$_3$(GaMgZr)$_{5}$ $O_{12}$(SGGG) by Liquid Phase Epitaxy (LPE). The changes of lattice mismatch and Bi concentration were investigated in the thick film growth as a function of PO/Bi$_2$ $O_3$ molar ratio, with keeping constant of substrate rotation speed, supercooling and growth time. It was grown that the lattice constant of the garnet single crystalline thick films and Bi content increased with decreasing of PO/Bi$_2$ $O_3$ molar ratio. Bi concentration decreased with increasing of the film thickness.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.8
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• pp.563-569
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• 1999

Boron doped CdS films were prepared by chemical bath deposition using boric acid$(H_3BO_3)$ as donor dopant source, and their electrical, optical properties were investigated as a function of doping concentration. In addition, effects of boron doping of CdS films on characteristics of CdS/CdTe solar cells were investigated. Boron doping highly decreased the resistivity and slightly increased optical band gap of CdS films. The lowest value of resistivity was $2 \Omega-cm \;at\; H_3BO_3/Cd(Ac)_2$ molar ratio of 0.1. For the molar ratio more than 0.1, however, the resistivity increased because of decreasing carrier concentration and mobility and showed similar value for undoped films. The photovoltaic characteristics of CdS/CdTe solar cells with boron doped CdS film improved due to the decrease of the conduction band-Fermi level energy gap of CdS films and the series resistance of solar cell.

• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1902-1909
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• 2005

A process for production of ethyl ester for use as biodiesel has been studied. The sodium hydroxide catalyzed transesterification of soybean oil with ethanol was carried out at different molar ratio of alcohol to oil, reaction temperature and catalyst amount for a constant agitation in two hours of reaction time. Central composite design and response surface methodology were used to determine optimum condition for producing biodiesel. It was found that ethanol to oil ratio and catalyst concentration have a positive influence on ester conversion as well as interaction effects between the three factors considered. An empirical model obtained was able to predict conversion as a function of ethanol to oil molar ratio, reaction temperature and catalyst concentration adequately. Optimum condition for soybean ethyl ester production was found to be moderate ethanol to oil ratio (10.5: 1), mild temperature range ($70^{\circ}C$) and high catalyst concentrations ($1.0\%$wt), with corresponding ester conversion of $93.0\%$.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.71-76
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• 2010

The densities and viscosities of 2-bromopropane-methanol binary mixtures had been determined using an digital vibrating U-tube densimeter and Ubbelohde capillary viscometer respectively from (298.15 to 318.15) K. The dependence of densities and viscosities on temperature and concentration had been correlated. The excess molar volume and the excess viscosity of the binary system were calculated from the experimental density and viscosity data. The excess molar volumes were related to compositions by polynomial regression and regression parameters and total RMSD deviations were obtained; the excess viscosities was related to compositions by Redlich-Kister equation and regression coefficients and total RMSD deviation of the excess viscosity for 2-bromopropane and methanol binary system were obtained. The results showed that the model agreed very well with the experimental data.

• Journal of Environmental Health Sciences
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• v.1 no.1
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• pp.21-27
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• 1974

This work was carried out to investigate the chemical properties of the chelate compounds which were produced with 2-methoxy-5-nitrophenol(MNG) and metal salt such as copper nitrate and manganese nitrate. And obtained results were as in the followings. 1) The binding ratio of the chelate compounds formation were determined by using the molar ratio concentration method and their chemical structures were identified by IR-spectrum. 2) In the absorbance measuring, 2-methoxy-5-nitrophenol coordinated with manganese and copper showed the maximum absorbance at $430 m\mu$ and $410 m\mu$ respectively. 3) The binding ratio of chelated compounds were measured by molar ratio method and continuous variation method with spectrophotometer, which was identified as 1:2. 4) The conditional formation constant(log Kn value) of manganese and copper chelate compounds were 6.70, 6.75, respectively according to the equation of $log\frac{A-AM\circ n MNG}{AMm MNG-A}=n log (M\circ)+log Kn$ 5) The dissociations degree of manganese and copper chelate compound were $2, 300{\times} 10^{-7}$, $2, 346{\times} 10^{-7}$ respectively according to the molar calculation method.