• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.751-755
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• 2005

Carbon dioxide, included in the flue gas from the combustion of fossil fuel, was known as a representative green house gas and various removal and utilization technologies of it has been studied for the prevention of global warming. This study was performed as an effort to find out a method to reuse carbon dioxide separated from flue gas by magnetite powder. Magnetite powder was synthesized using various oxidizers and alkalinity controlled aqueous solutions of $FeSO_4{\cdot}7H_2O$ and NaOH at 50, 80, 90, $100^{\circ}C$ and analyzed by XRD and SEM. The analysis results showed that magnetite powder synthesized at higher alkalinity and temperature had crystalline spinel and cubic structure. The reduction by hydrogen and the oxidation by carbon dioxide of synthesized powder were studied by TGA. The results showed that magnetite powder synthesized at low alkalinity and temperature was non-cubical amorphous but crystalline and cubical at high alkalinity and temperature. Comparing magnetite powders synthesized using oxidants(air and oxygen) and nitrogen, magnetite powder using more oxygen containing oxidant synthesized more crystalline magnetite powder. The experimental results of redox reaction of the synthesized magnetite powder showed that the reduction by hydrogen and the oxidation by carbon dioxide were seldom observed below $400^{\circ}C$ and observed well at $500^{\circ}C$. Magnetite powder synthesized at $100^{\circ}C$ and alkalinity(molal concentration ratio of $FeSO_4{\cdot}7H_2O$ to NaOH) of 2.0 using $O_2$ showed the highest reduction of 27.15 wt％ and oxidation of 26.73 wt％, especially at reaction temperature of $500^{\circ}C$.

• Economic and Environmental Geology
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• v.8 no.1
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• pp.1-23
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• 1975

The subject of this study deals with phase relations between stannite ($Cu_2FeSnS_4$) and sphalerite (${\beta}-ZnS$)/wurtzite (${\alpha}-ZnS$). The phase relations were systematically investigated from liquidus temperature to $400^{\circ}C$ under controlled conditions. ${\beta}-stannite$ (tetragonal) is stable up to $706{\pm}5^{\circ}C$, where it inverts to a high-temperature polymorph ${\alpha}-stannite$ (cubic) melting congruently at $867{\pm}5^{\circ}C$. Sphalerite (cubic, ${\beta}-ZnS$) inverts at $1013{\pm}3^{\circ}C$ to wurtzite, which is the hexagonal hightemperature polymorph of ZnS. Between ${\alpha}-stannite$ and sphalerite a complete solid solution series exists above approximately $870^{\circ}C$ up to solidus temperature. The melting temperature of ${\alpha}-stannite$ rises towards sphalerite and reaches a maximum at $1074{\pm}3^{\circ}C$, which is the peritectic with the composition of 91 wt. % sphalerite and 9 wt. % ${\alpha}-stannite$. At this temperature, wurtzite takes only 5wt. % ${\alpha}-stannite$ in solid solution which decreases with increasing temperature. The inverson temperature of ${\alpha}/{\beta}-stannite$ is lowered with increasing amounts of sphalerite in solid solution down to $614{\pm}7^{\circ}C$, which is the eutectoid with the composition of 13 wt. % sphalerite and 87 wt. % ${\alpha}-stannite$. Here, ${\beta}-stannite$ contains only 10wt. % sphalerite in solid solution. With decreasing temperature, the ranges of the solid solution on both sides of the system narrow. The phase relations in the above pure system changed due to the FeS impurities in the sphalerite solid solution. The eutectoid increased from $614{\pm}7^{\circ}C$ up to $695{\pm}5^{\circ}C$ (5 wt. % FeS) and $700{\pm}5^{\circ}C$ (10wt. % FeS), while the peritectic decreased from $1074{\pm}3^{\circ}C$ down to $1036{\pm}3^{\circ}C$ (wt. %FeS) and $987{\pm}3^{\circ}C$ (10wt. %FeS). A most notable change is the appearance of non-binary regions. An important feature is the combination of this study system with the experimental results reported by Sprinfer (1972). If a stannite-kesterite solid solution is used in the place of stannite as a bulk composition, the inversion temperature is lowered to less than $400^{\circ}C$ which belongs to temperatures of the hydrothermal region.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.6
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• pp.797-803
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• 2017

Objective: Effects of nitrogen supplementation associated with different levels of starch on voluntary intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage (Brachiaria decumbens hay, 7.4% crude protein, CP) were evaluated using ruminal and abomasal cannulated steers. Methods: Five European${\times}$Zebu young bulls (186 kg body weight, BW) were distributed according to a $5{\times}5$ Latin square. The following treatments were evaluated: control, supplementation with 300 g CP/d (0:1), supplementation with 300 g starch/d and 300 g CP/d (1:1), supplementation with 600 g starch/d and 300 g CP/d (2:1), and supplementation with 900 g starch/d and 300 g CP/d (3:1). A mixture of nitrogenous compounds provided 1/3 from true protein (casein) and 2/3 from non-protein nitrogen (mixture of urea and ammonium sulphate, 9:1) was used as the nitrogen supplement. In order to supply energy a unique source of corn starch was used. Results: Supplements increased (p<0.05) dry matter intake, but did not affect (p>0.05) forage intake. There was a cubic effect (p<0.05) of starch on voluntary intake. This was attributed to the highest forage intake (g/kg BW) when using the 2:1 starch:CP ratio. Supplements increased (p<0.05) organic matter (OM) digestibility, but did not affect (p>0.05) neutral detergent fibre corrected for ash and protein (NDFap) digestibility. There was a positive linear effect (p<0.05) of the amount of starch supplemented on OM digestibility. Total NDFap digestibility was not affected (p>0.05) by the amount of supplemental starch. Ruminal ammonia nitrogen concentrations were higher (p<0.05) in supplemented animals, however, a negative linear effect (p<0.05) of amount of starch was observed. Supplements increased (p<0.05) the nitrogen balance (NB) and efficiency of nitrogen utilization. These effects were attributed to increased body anabolism, supported by higher (p<0.05) serum concentration of insulin-like growth factor 1. Increasing the amount of starch tended (p<0.06) to linearly increase the NB. In spite of this, there was a highest NB value for the 2:1 starch:CP ratio amongst the treatments with supplementation. Conclusion: Nitrogen supplementation in cattle fed low-quality tropical forage increases nitrogen retention in the animal's body. An additional supply of starch increases nitrogen retention by increasing energy availability for both rumen and animal metabolism.

• Progress in Medical Physics
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• v.10 no.2
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• pp.103-114
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• 1999

In this study, as a preliminary study for developing a full 3D photon dose calculation algorithm, We developed 2.5D photon dose calculation algorithm by extending 2D calculation algorithm to allow non-coplanar configurations of photon beams. For this purpose, we defined the 3d patient coordinate system and the 3d beam coordinate system, which are appropriate to 3d treatment planning and dose calculation. and then, calculate a transformation matrix between them. For dose calculation, we extended 2d "Clarkson-Cunningham" model to 3d one, which can calculate wedge fields as well as regular and irregular fields on arbitrary plane. The simple Batho's power-law method was implemented as an inhomogeneity correction. We evaluated the accuracy of our dose model following procedures of AAPM TG#23; radiation treatment planning dosimetry verifications for 4MV of Varian Clinac-4. As results, PDDs (percent depth dose) of cubic fields, the accuracy of calculation are within 1% except buildup region, and $\pm$3% for irregular fields and wedge fields. And for 45$^{\circ}$ oblique incident beam, the deviations between measurements and calculations are within $\pm$4%. In the case of inhomogeneity correction, the calculation underestimate 7% at the lung/water boundary and overestimate 3% at the bone/water boundary. At the conclusions, we found out our model can predict dose with 5% accuracy at the general condition. we expect our model can be used as a tool for educational and research purpose.. purpose..

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.447-455
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• 2013

A micro-mechanical pipe network model with the shape of a cube was developed to simulate the behavior of fluid flow through a porous medium. The fluid-flow mechanism through the cubic pipe network channels was defined mainly by introducing a well-known percolation theory (Stauffer and Aharony, 1994). A non-uniform flow generally appeared because all of the pipe diameters were allocated individually in a stochastic manner based on a given pore-size distribution curve and porosity. Fluid was supplied to one surface of the pipe network under a certain driving pressure head and allowed to percolate through the pipe networks. A percolation condition defined by capillary pressure with respect to each pipe diameter was applied first to all of the network pipes. That is, depending on pipe diameter, the fluid may or may not penetrate a specific pipe. Once pore pressures had reached equilibrium and steady-state flow had been attained throughout the network system, Darcy's law was used to compute the resultant permeability. This study investigated the sensitivity of network size to permeability calculations in order to find out the optimum network size which would be used for all the network modelling in this study. Mean pore size and pore size distribution curve obtained from field are used to define each of pipe sizes as being representative of actual oil sites. The calculated and measured permeabilities are in good agreement.

• Journal of the Korean Society of Costume
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• v.18
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• pp.291-306
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• 1992

From the mid-1980s '91s, remarkable Ethnicism and Primitivism in the Europe fashion trend could be represented as an exotic taste longing for secenery and emotion of non-europe area in the West. These phenomenon could be found out in connection with Acculturation, which means when two different cultures or more were contacted they were identified or merged in process of diffusion and change of them. This point of view was the culture anthropologic one that make a comparison and analysis of sameness and difference between cultures. The purpose of this study was to illuminate exotic taste represented in costume in the cluture-anthroplogic aspect, to compare with beauty of costume that each culture of costume and the meaning of the times due to those differences. an aspect of the exotic taste and character in the western costume that was inspected by dividing into 'Primitivism', 'Oriental element' and 'the element of a national costume in the East European bloc ' were as follows; First, Primitivism had something in common with what was pursued in the trend of Modern Art, through the late 19th century to the early 20th century. In fashion fettered by technique, the creation expressed in a free was and showed simple beauty of costume. At the same time, pure emotion expression, creative power and witty strong expression give the cognition of transcendency breaking the routine and the cognition of complexity of an included conception. Those are garments showing not only the primitive thought and mysticism but a fancy, an abstraction, and a life. Colors and accessaries which described nature and matched simple costume composition to the expression of various material or patterns transmitted the image of the primitive strongly. Second, "Drental element" which had an effect on western custome historically in a long time had outstanding luxurios adornmental beauty of custome. Extending from the Arab stated India, China, Korea, Japan, each national costume with a gay national culture became one of motif. Various ornamental factors expressed on Trapez Line, Sime Line and Drape, or Raied style, which did not restrict the body. Those were not only functional Easy Look, but were also satisfying human's ornamental desire. Third, national factors in the East European bloc are theme that begins to be embossed in the late 80's. In view of a political change and cultural situation with a double character of Europe and Orient, it was estimated that national factors have great importance in fashion. Item concerned with new concern appeared at Autumn & Winter collection. It shows elegant and graceful beauty of costume by adding a fur or jewel to simple form. These national factors in the East European bloc are simple form, but shows the difference in more cubic formation than form expressed in Primitivism or Oriental factors Exotic taste appeared form 80's to 91's, is thought to create an forgotten romantic emotion and traditional fashion

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.707-711
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• 2014

The $0.99Bi_{0.5}(Na_{0.78}K_{0.22})_{0.5}TiO_3-0.01LaAlO_3$, $0.01LaMnO_3$ or $0.01LaFeO_3$ (0.99BNKT-0.01LA, 0.01LM or 0.01LF) ceramics were prepared by a conventional mixed mothod. The structure and morphology of the lead free ceramics were characterized by XRD (X-ray diffraction) and FE-SEM (field emission scanning electron microscopy). XRD results indicated that the BNKT ceramics modified by LA, LM or LF induced a transition from a ferroelectric tetragonal to a non-polar pseudo-cubic phase, leading to decrease in the remnant polarization ($P_r$) and coercive field ($E_c$) in the P-E hysterisis loops. The effects of the BNKT ceramics modified by La-based $ABO_3$ pervskite structure on the electric-field induced strain were investigated, and the largest normalized unipolar strain ($S_{max}/E_{max}$) was found in BNKT-0.01LF ceramic.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.1-11
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• 2003

In order to measure aperture variation dependent on normal stress and to characterize on relationship between aperture variation and hydraulic conductivity this study measured apertures of rock fractures under a high resolution confocal laser scanning microscope (CLSM) with application of five stages of uniaxial normal stresses. From this method the response of aperture can be continuously characterized on one specimen by different loads of normal stress. The results of measurements showed a rough geometry of fracture bearing non-uniform aperture. They also revealed different values of aperture variations according to the load stages on each position along a fracture due to the fracture roughness. Laboratory permeability tests were also conducted to evaluate the changes of permeability coefficients related to the aperture variations by different loads. The results of permeability tests revealed that the hydraulic conductivity was not reduced at a fixed rate with increase of normal load. Moreover, the rates of aperture variations did not match to those of hydraulic conductivity. The hydraulic conductivity calculated in this study did not follow the cubic law, representing that the parallel plate model is not suitable to express the fracture geometry corresponding to the results of aperture measurements under the CLSM.

• Journal of the Mineralogical Society of Korea
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• v.24 no.1
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• pp.37-42
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• 2011

Magnetic properties at low-temperatures can diagnose the presence of certain magnetic minerals in rocks. At the Verwey transition temperature ($T_v$, ~105~120 K), magnetite transforms from monoclinic to cubic structure as the temperature increases. At the isotropic point ($T_i$, ~135 K), magnetocrystalline anisotropic constant of magnetite passes through zero (from negative to positive) as the temperature decreases so that its optimal remanence acquisition axis changes from [111] to [001]. A sharp remanence drop was observed at $T_v$ during warming of LTSIRM (low-temperature saturation isothermal remanent magnetization). For cooling of RTSIRM (room-temperature saturation isothermal remanent magnetization), the remanence decreased on passing $T_i$ and $T_v$. On warming of RTSIRM, remanence recovery becomes more prominent as the average grain size of magnetite increases. In summary, the SIRM memory decreases with increasing grain size of magnetite. A similar, but rather gradual, remanence transition occurs for natural samples due to contribution of cations other than Fe. As a non-destructive tool, low-temperature magnetic behavior is sensitive to unravel the magnetic remanence carriers in terrestrial rocks or meteorites.

• Journal of Korean Society of Forest Science
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• v.70 no.1
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• pp.84-90
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• 1985

The objective of this study is to analyze the market structure and price formation status of imported log from overseas which has leadership of timber price decision mechanism in Korea. The results obtained are as follows; 1) The 53 percents of the total 134 log importing companies are the small scale companies which import less than ten thousand cubic meters per year, and are mainly aimed to do agent task of importing log. 2) The market structure of imported log formed high level 01 oligopolistic structure, but did not make excess profit of oligopoly because of excess import. 3) The bargaining power of Korea on the price decision process in the overseas log exporting market is very weak, because the market has the bilateral oligopoly structure, and the non-systematic importing behavior of Korean log importing companies make the bargaining power of Korea more weak. 4) It is analyzed that Korean domestic marketing system is comperatively simple, but reasonable marketing system is not established because of the disorder of the marketing behavior. From the results obtained above, it is proposed that the government has to establish the general institutional system to control the supply-demand and marketing problems of imported log, in order to establish the rational structure of market and price decision system of imported log.