• Korean Journal of Soil Science and Fertilizer
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• v.49 no.2
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• pp.132-137
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• 2016

Field monitoring was performed to evaluate the chemical properties of 260 paddy soils every 4 years from 1999 to 2015 in Gyeongnam province. Soil chemical properties, including soil pH, electrical conductivity, amount of organic matter (OM), available phosphate ($P_2O_5$), exchangeable potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na), and available silicate ($SiO_2$) were analyzed. In 2015, the average values of pH, OM, available $P_2O_5$, exchangeable K, Ca, and Mg, and available $SiO_2$ was 5.8, $30g\;kg^{-1}$, $222mg\;kg^{-1}$, $0.37cmol_c\;kg^{-1}$, $6.5cmol_c\;kg^{-1}$, and $1.4cmol_c\;kg^{-1}$, $252mg\;kg^{-1}$, respectively. The frequency distribution within optimum range of paddy soils was 49.2%, 20.8%, 18.5%, and 5.8% for soil pH, OM, available $P_2O_5$, and available $SiO_2$, respectively. The available $P_2O_5$ concentrations in 2015 was excess level with portion of 58% and did not alter significantly during the experimental period. Although the average of available $SiO_2$ concentration has tended to increase with every year, the insufficient proportion of available $SiO_2$ concentration in 2015 was 48%. These results indicated that a balanced management of soil chemical properties can properly control the amount of fertilizer applied for sustainable agriculture in paddy field.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.723-727
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• 2003

Recently the ab initio effective valence shell Hamiltonian method $H^v$ has been extended to treat spin-orbit coupling in atoms or molecules. The quasidegenerate many-body perturbation theory based $H^v$ method has an advantage of determining the spin-orbit coupling energies of all valence states for both the neutral species and its ions with a similar accuracy from a single computation of the effective spin-orbit coupling operator. The new spin-orbit $H^v$ method is applied to calculating the fine structure splittings of the valence states of SiH, $SiH^+$, and $SiH^{2+}$ not only to assess the accuracy of the method but also to investigate the spin-orbit interaction of highly excited states of SiH species. The computed spin-orbit splittings for ground states are in good agreement with experiment and the few available ab initio computations. The ordering of fine structure levels of the bound and quasi-bound spin-orbit coupled valence states of SiH and its ions, for which neither experiment nor theory is available, is predicted.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.407-416
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• 2003

Although the requirement and optimum soil level of Si for oriental melon are still not well understood, silicate fertilizer is commonly applied to the oriental melon in plastic film houses where soil silicate level is relatively high. In this research the effects of silicate fertilizer on growth, fruit yield and fruit quality of oriental melon, and soil properties were investigated in plastic film house where the soil available silicate was $212mg\;SiO_2\;kg^{-1}$. Silicate fertilizer was applied in the rates of 100, 200, and $300kg\;10a^{-1}$. The application of silicate fertilizer could not increase the early growth of oriental melon, and also the fruit yield and quality were not different among the treatments. Available Si and P contents in soils and also Si and P contents in leaf of oriental melon of the different treatments were not significantly different. In the relationship between total Si in oriental melon leaf and soil silicate extracted by 1 N sodium acetate, optimum soil available silicate level for oriental melon was found to be around $100mg\;SiO_2\;kg^{-1}$. These results indicate that the additional silicate fertilization in soils of available silicate higher than $100mg\;SiO_2\;kg^{-1}$ is unnecessary, and such application of silicate can not have any beneficial effect on the growth and fruit yield of oriental melon.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.129-132
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• 2000

In this paper, a 1.8㎓ low noise amplifier was designed and simulated using 0.2$\mu\textrm{m}$ Si CMOS process. Noise characteristics and s parameters were extracted for the 300$\mu\textrm{m}$ gate width and 0.25$\mu\textrm{m}$ gate length NMOS transistors. For high available power gain, each stage was designed cascode type. It revealed available power gain of 23.5dB, noise figure of 2.0dB, power consumption of 15㎽ at 2.5V. It was shown that designed low noise amplifier had good RF performance. Designed Si CMOS LNA is expected to be used for RF front-end in transceiver.

• Journal of Welding and Joining
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• v.17 no.6
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• pp.62-69
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• 1999

The advantages of Thermal sprayed coatings as a replacement for cast iron liners are reduced weight, better heat transfer and reduced cost. One of the most important performance attributes of a cylinder bore coating is its wear resistance, since it must survive the abrasive sliding of both the piston rings and the piston skirt. In this study, composite powders were prepared by ball milling of Al-13Si-3Mg(wt%) alloy with SiC particles. The concentrations of SiC were 40 and 60wt%. The composite powders were sprayed using Metco-9MB plasma torch. Plasma sprayed coatings were heat-treated at 500℃ for 3 hours. The wear resistances of the plasma sprayed coatings were found to improve with heat treatment and superior to the commercially available G.C.I.(gray cast iron). AlSiMg-40SiC heat-treated coatings showed the best wear resistance in this study.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.61-65
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• 2015

The effect of Sr addition on the flexural strength of bulk SiOC ceramics was investigated in polymer-derived SiOC ceramics prepared by conventional hot pressing. Crack-free, dense SiOC discs with a 30 mm diameter were successfully fabricated from commercially available polysiloxane with 1 mol% strontium isopropoxide derived Sr as an additive. Agglomerates formed after the pyrolysis of polysiloxane led to the formation of domain-like structures. The flexural strength of bulk SiOC was strongly dependent on the domain size formed and Sr addition. Both the minimization of the agglomerate size in the starting powders by milling after pyrolysis and the addition of Sr, which reinforces the SiOC structure, are efficient ways to improve the flexural strength of bulk SiOC ceramics. The typical flexural strength of bulk Sr-doped SiOC ceramics fabricated from submicron-sized SiOC powders was ~209 MPa.

• Korean Journal of Environmental Agriculture
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• v.23 no.2
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• pp.104-110
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• 2004

Although silicon (Si) has been Down to be an essential element fer rice growth, the optimum soil level of Si for upland crops remains unestablished. This study was conducted to estimate the availability of Si fertilizer in upland soils, and also effect of the Si fertilizer on soil pH was examined. Different application rates of Si fertilizer were tested using faur soils of different available Si levels and pHs in a series of laboratory incubation study. The treatments included Si fertilizer levels of 100, 200, and 300 kg/10a. Also to examine the effects of compost and lime on the availability of Si fertilizer in upland soil, treatment of silicate fertilizer 200 kg/10a + compost 1,000 kg/10a and lime alone treatment were included. Changes of Si availability in the soils during the incubation period were measured by 1 N NaOAc extraction procedure. Availability of Si fertilizer was different among the tested soils, and about $9.1{\sim}19.2%$ of the applied Si fertilizer was extracted after 60 days laboratory incubation. Application rate could not influence the availability of Si fertilizer. Application of compost with Si fertilizer could not increase Si availability in upland soils, but lime treatment could increase Si availability. Soil pH increased by application of Si fertilizer, but the effect of Si fertilizer on soil pH was minimal. When Si fertilizer is applied on the purpose of Si nutrition in acid upland soils, lime treatment should be coupled with the Si fertilizer for remediation of soil acidity.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1527-1533
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• 2011

The reaction of gas-phase atomic hydrogen with oxygen atoms chemisorbed on a silicon surface is studied by use of the classical trajectory approach. We have calculated the probability of the OH formation and energy deposit of the reaction exothermicity in the newly formed OH in the gas-surface reaction H(g) + O(ad)/Si${\rightarrow}$ OH(g) + Si. All reactive events occur in a single impact collision on a subpicosecond scale, following the Eley-Rideal mechanism. These events occur in a localized region around the adatom site on the surface. The reaction probability is dependent upon the gas temperature and shows the maximum near 1000 K, but it is essentially independent of the surface temperature. The reaction probability is also independent upon the initial excitation of the O-Si vibration. The reaction energy available for the product state is carried away by the desorbing OH in its translational and vibrational motions. When the initial excitation of the O-Si vibration increases, translational and vibrational energies of OH rise accordingly, while the energy shared by rotational motion varies only slightly. Flow of energy between the reaction zone and the solid has been incorporated in trajectory calculations, but the amount of energy propagated into the solid is only a few percent of the available energy released in the OH formation.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1169-1175
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• 1994

Five Al2O3/SiC/metal composites with four different particle sizes of green SiC abrasive grains are grown by the directed oxidation of an commercially available Al-alloy. Oxidation was conducted in air at 100$0^{\circ}C$, 96 hours long. Slip casted SiC-fillers were placed on the alloy or SiC powder deposited up to the required layer thickness. Their microstructures are described and measurements of density, elastic constants, frexural strength, fracture toughness and work of fracture are reported. The results are compared with those of commercial dense sintered Al2O3. The properties of produced materials have a strong relationship to not only the properties of Al2O3, SiC, Al and Si but also to the phase share and phase distribution. The composite materials are dense (0.5% porosity), tough (KIC = 3.4~6.4 MPa{{{{ SQRT { m} }}), strong ({{{{ sigma }}B = 170~345 MPa) and reasonably shrinkage free producible. The reinforcements is attained mainly through the plastic deformation of ductile metal phase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.650-656
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• 2003

In 1995, a group of representatives from the integrated circuits and computer-aided design industries presented a industry standard bipolar model called the VBIC model. The VBIC model includes the improved Early effect, quasi-saturation, substrate parasitic, avalanche multiplication, and self-heating which are not available in the conventional SGP model. This paper applies VBIC model for SiGe HBT device and develops an accurate and efficient methodology to extract all the DC and AC parameters of the VBIC model for SiGe HBT device at room temperature. Simulated results by the extracted VBIC model parameter are compared with the measurement data and show very good agreement in both DC and s-parameters prediction.