• Journal of Bio-Environment Control
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• v.24 no.2
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• pp.100-105
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• 2015

The calculation method of infiltration loss in greenhouse has different ideas in each design standard, so there is a big difference in each method according to the size of greenhouses, it is necessary to establish a more accurate method that can be applied to the domestic. In order to provide basic data for the formulation of the calculation method of greenhouse heating load, we measured the infiltration rates using the tracer gas method in plastic greenhouses equipped with various thermal curtains. And then the calculation methods of infiltration loss in greenhouses were reviewed. Infiltration rates of the multi-span and single-span greenhouses were measured in the range of $0.042{\sim}0.245h^{-1}$ and $0.056{\sim}0.336h^{-1}$ respectively, single-span greenhouses appeared to be slightly larger. Infiltration rate of the greenhouse has been shown to significantly decrease depending on the number of thermal curtain layers without separation of single-span and multi-span. As the temperature differences between indoor and outdoor increase, the infiltration rates tended to increase. In the range of low wind speed during the experiments, changes of infiltration rate according to the outdoor wind speed could not find a consistent trend. Infiltration rates for the greenhouse heating design need to present the values at the appropriate temperature difference between indoor and outdoor. The change in the infiltration rate according to the wind speed does not need to be considered because the maximum heating load is calculated at a low wind speed range. However the correction factors to increase slightly the maximum heating load including the overall heat transfer coefficient should be applied at the strong wind regions. After reviewing the calculation method of infiltration loss, a method of using the infiltration heat transfer coefficient and the greenhouse covering area was found to have a problem, a method of using the infiltration rate and the greenhouse volume was determined to be reasonable.

• Journal of The Korean Society of Grassland and Forage Science
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• v.32 no.1
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• pp.39-48
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• 2012

This study was conducted to investigate effects of different levels of seleniferous whole crop barley (WCB) supplementation on performance, and blood characteristics as physiological responses in growing pigs. A total of 20 cross-bred pigs ((Landrace ${\times}$ Yorkshire) ${\times}$ Duroc) were divided into 4 treatments of 5 pigs each and experimental period lasted for 6 weeks. They were fed diets containing 0.1 (non-seleniferous WCB as controls), 0.2, 0.4, and 0.6 mg/kg levels of selenium (Se) by supplementing seleniferous WCB, and non-seleniferous or seleniferous WCB was formulated to 5% level in total ration. The diets were isonitrogenous (18% crude protein) and isocaloric (3,500 kcal/kg digestible energy) across treatments. Increasing levels of seleniferous WCB supplements did not affect feed intake and BW gain, and blood total protein concentration was (p<0.05) significantly higher for 0.2 mg/kg Se treatments than for controls. On d 14, blood albumin concentration was higher (p<0.05) for seleniferous WCB supplemented groups than for control group. Contrarily, blood glucose concentration was tended to be higher for controls than for seleniferous WCB groups. Blood total lipid concentration was significantly (p<0.05) lowered with increasing levels of seleniferous WCB. Serum glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase did not have any difference among treatments. It was tended that blood total cholesterol and triglyceride were lowered with increasing levels of seleniferous WCB. Blood Se concentration was significantly (p<0.05) increased with increasing levels of seleniferous WCB. The results indicate that Se present in seleniferous WCB had favorable effects on blood characteristics and blood Se increased by supplementing seleniferous WCB implies not only a good intestinal absorption of Se present in WCB but also the possibility of Se transfer into tissues.

• Korean Journal of Environmental Agriculture
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• v.15 no.1
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• pp.11-18
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• 1996

A greenhouse experiment on the Sr-90 uptake by peanut and sesame was conducted through pot cultures on a sandy loam soil of pH 6.35 treated with Sr-90 in 5.2 and 31.2Bq per gram. The rate of Sr-90 transfer from soil to each plant part, the ratio of Sr-90 concentration in the part to the concentration in soil, and the patterns of their temporal changes were not, on the whole, significantly different between the two treatments. About 0.7 and 0.5 % of Sr-90 in soil transferred to all the mature plants of peanut and sesame, respectively, with the radioactivities in their roots not counted. Only 4% and less than 15% of Sr-90 absorbed by peanut and sesame, respectively, translocated to their seeds. Both crops showed the highest Sr-90 concentration in the leaf and the lowest in the seed. At maturities, the concentration ratio in dry seed was 0.4 in peanut and 3.3 in sesame and that in dry leaf was 12.5 and 10.7, respectively. Sr-90 concentrations in the top 15 cm soil after harvests averaged about 80 % of the concentrations at starting. Sr-90 uptake resulted in neither growth inhibition nor yield decrease.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.375-375
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• 2012

Graphene is a sp2-hybridized carbon sheet with an atomic-level thickness and a wide range of graphene applications has been intensely investigated due to its unique electrical, optical, and mechanical properties. In particular, hybrid graphene structures combined with various nanomaterials have been studied in energy- and sensor-based applications due to the high conductivity, large surface area and enhanced reactivity of the nanostructures. Conventional metal-catalytic growth method, however, makes useful applications difficult since a transfer process, used to separate graphene from the metal substrate, should be required. Recently several papers have been published on direct graphene growth on the two dimensional planar substrates, but it is necessary to explore a direct growth of hierarchical nanostructures for the future graphene applications. In this study, uniform graphene layers were successfully synthesized on highly dense dielectric nanowires (NWs) without any external catalysts. We also demonstrated that the graphene morphology on NWs can be controlled by the growth parameters, such as temperature or partial pressure in chemical vapor deposition (CVD) system. This direct growth method can be readily applied to the fabrication of nanoscale graphene electrode with designed structures because a wide range of nanostructured template is available. In addition, we believe that the direct growth growth approach and morphological control of graphene are promising for the advanced graphene applications such as super capacitors or bio-sensors.

• Journal of the Korean Chemical Society
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• v.24 no.5
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• pp.380-392
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• 1980

Six coordinate low spin iron(Ⅱ) complexes of vicinal-dioximes, [Fe$(DH)_2B_2$] and [Fe$(DH)_2$B(CO)]($(DH)_2$=$(CHDH)_2$(bis(1,2-cyclohexadinedioximato) bivalent anion), $(DPGH)_2$-(bis(diphenylglyoximato) bivalent anion), $(F{\alpha}DH)_2(bis(furil-{\alpha}-dioximato)$ bivalent anion); B = monodentate neutral nitrogen base), have been prepared and their physical properties have been investigated with respect to the effects of the equatorial ligands, $(DH)_2$. The order of ${\pi}$-acceptor CO stretching frequency for [Fe$(DH)_2$B(CO)] is $(F{\alpha}DH)_2$ > $(DPGH)_2$> $(CHDH)_2$, while non-${\pi}$-acceptor $NH_3$ stretching frequencies for [Fe$(DH)_2(NH_3)_2$] show the opposite order to that of CO, i.e., $(CHDH)_2$ > $(DPGH)_2$ > $(F{\alpha}DH)_2$. These infrared spectral data together with Fe-N (oxime) and Fe-N (oxime) and Fe-N (B) stretching frequency data suggest that the nitrogen atoms of $(CHDH)_2$ are more basic and poorer ${\pi}$-acceptors than the corresponding nitrogen atoms of $(DPGH)_2$ and $(F{\alpha}DH)_2$, respectively. It has been found from the electronic spectral data of [Fe$(DH)_2$] and [Fe$(DH)_2$B(CO)] that the energy of the charge transfer band from iron(Ⅱ) to $(DH)_2$ increases as the basicity of $(DH)_2$ increases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.11
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• pp.745-753
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• 2016

Micro methanol-steam reformer for fuel cell can effectively produce hydrogen as reforming response to steam takes place in low temperature (less than $250^{\circ}C$). This study conducted numerical research on this reformer. First, study set wall temperature of the reformer at 100, 140, 180 and $220^{\circ}C$ while methanol conversion efficiency was set in 0, 0.072, 3.83 and 46.51% respectively. Then, porosity of catalyst was set in 0.1, 0.35, 0.6 and 0.85 and although there was no significant difference in methanol conversion efficiency, values of pressure drop were 4645.97, 59.50, 5.12 and 0.45 kPa respectively. This study verified that methanol-steam reformer rarely responds under the temperature of $180^{\circ}C$ and porosity does not have much effect on methanol conversion efficiency if the fluid flowing through reformer lowers activation energy by sufficiently contacting reformer.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.776-784
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• 2016

In this study, green Larix kaempferi lumber was heat-treated by using superheated steam (SHS) at a pilot scale and then various physico-mechanical properties of the heat-treated wood were evaluated and compared with the properties of conventional hot air (HA) heat-treated wood. Decay resistance of brown rot fungi and compressive strength parallel to the grain of the SHS heat-treated wood without occurrence of drying check from green lumber were increased. On the other hand, density, equilibrium moisture content, shrinkage, and bending strength of the SHS heat-treated wood were lower than those of the conventional HA heat-treated wood. Because heat transfer and thermal hydrolysis of SHS heat treatment was accelerated by a large amount of water, the effect of SHS heat treatment on the physico-mechanical properties was higher than that of HA heat treatment at the similar conditions of temperature and time. From the results of this study, because green lumber can be heat-treated without occurrence of cracks or checks by using SHS and similar heat treatment effect on the physico-mechanical properties of wood can be produced despite a low temperature or short time of heat treatment, it is expected that heat time and energy consumption could be reduced by using SHS.

• Economic and Environmental Geology
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• v.47 no.5
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• pp.489-496
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• 2014

The occurrence and mineralogical characteristics of asbestos in dolostone at Ungdo, Seosan were investigated by analyses of PLM, XRD, and SEM/EDS. Representative outcrops of dolostone at Ungdo were examined and four dolostone samples were collected according the occurrence type to identify the shape of asbestos in dolostone samples. The host rock of dolostone had been produced from the hydrothermal alteration and/or thermal metamorphism of which main source was assumed as the acidic granite. Tremolites were observed near the cracks or fractures of the dolostone as tamping or gob types. From the mineralogical analyses, main minerals of dolostone were dolomite with calcite, quartz, talc, amphibole, and pyroxene. From SEM/EDS analyses, tremolite-actinolite asbestoses were observed in dolostone and their shapes were prismatic and fibrous (less than $1{\mu}m$ in width). Non-asbestos prismatic forms were also found and they would transfer to asbestos particles resulting from the cleavage and fracture of the prismatic particles. Overall results suggest that asbestoses in Ungdo dolosotnes were mainly tremolite-actinolite and they were originated from the hydrothermal alteration of Ca-Mg rich dolostone.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.441-441
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• 2009

Dye-sensitized solar cells (DSSCs) have been widely investigated as a next-generation solar cell because of their simple fabrication process and low coats. The cells use a porous nanocrystalline TiO2 matrix coated with a sensitizer dye that acts as the light-harvesting element. The photo-exited dye injects electrons into the $TiO_2$ particles, and the oxide dye reacts with I- in the electrolyte in regenerative cycle that is completed by the reduction of $I_3^-$ at a platinum-coated counter electrode. Since $TiO_2$ porous film plays a key role in the enhancement of photoelectric conversion efficiency of DSSC, many scientists focus their researches on it. Especially, a high light-to-electricity conversion efficiency results from particle size and crystallographic phase, film porosity, surface structure, charge and surface area to volume ratio of porous $TiO_2$ electrodes, on which the dye can be sufficiently adsorbed. Effective treatment of the photoanode is important to improve DSSC performance. In this paper, to obtain properties of surface and dispersion as nitric acid treated $TiO_2$ photoelectrode was investigate. The photovoltaic characteristics of DSSCs based the electrode fabricated by nitric acid pre-treatment $TiO_2$ materials gave better performances on both of short circuit current density and open circuit voltage. We compare dispersion of $TiO_2$ nanoparticles before and after nitric acid treatment and measured Ti oxidized state from XPS. Low charge transfer resistance was obtained in nitric acid treated sample than that of untreated sample. The dye-sensitized solar cell based on the nitric acid treatment had open-circuit voltage of 0.71 V, a short-circuit current of 15.2 mAcm-2 and an energy conversion efficiency of 6.6 % under light intensity of $100\;mWcm^{-2}$. About 14 % increases in efficiency obtained when the $TiO_2$ electrode was treated by nitric acid.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1639-1645
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• 1991

Because of the important role LD converters play in the production of high quality steel, various dynamic models have been attempted in the past by many researchers not only to understand the complex chemical reactions that take place in the converter process but also to assist the converter operation itself using computers. And yet no single dynamic model was found to be completely satisfactory because of the complexity involved with the process. The process indeed involves dynamic energy and mass balances at high temperatures accompanied by complex chemical reactions and transport phenomena in the molten state. In the present study, a mathematical model describing the dynamic behavior of LD converter process has been developed. The dynamic model describes the time behavior of the temperature and the concentrations of chemical species in the hot metal bath and slag. The analysis was greatly facilitated by dividing the entire process into three zones according to the physical boundaries and reaction mechanisms. These three zones were hot metal (zone 1), slag (zone 2) and emulsion (zone 3) zones. The removal rate of Si, C, Mn and P and the rate of Fe oxidation in the hot metal bath, and the change of composition in the slag were obtained as functions of time, operating conditions and kinetic parameters. The temperature behavior in the metal bath and the slag was also obtained by considering the heat transfer between the mixing and the slag zones and the heat generated from chemical reactions involving oxygen blowing. To identify the unknown parameters in the equations and simulate the dynamic model, Hooke and Jeeves parttern search and Runge-Kutta integration algorithm were used. By testing and fitting the model with the data obtained from the operation of POSCO #2 steelmaking plant, the dynamic model was able to predict the characteristics of the main components in the LD converter. It was possible to predict the optimum CO gas recovery by computer simulation