• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.4
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• pp.106-113
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• 1997

Dynamic loading of structures often causes excursions of stresses well into the inelastic range, and the influence of the geometric changes on the dynamic response is also significant in many cases. Therefore, both material and geometric nonlinearity effects should be considered in case that a dynamic load acts on the structure. A structure in a nuclear power plant is a structure of importance which puts emphasis on safety. A nuclear container is a pressure vessel subject to internal pressure and this structure is constructed by a reinforced concrete or a pre-stressed concrete. In this study, the material nonlinearity effect on the dynamic response is formulated by the elasto-viscoplastic model highly corresponding to the real behavior of the material. Also, the geometrically nonlinear behavior is taken into account using a total Lagrangian coordinate system, and the equilibrium equation of motion is numerically solved by a central difference scheme. The constitutive relation of concrete is modeled according to a Drucker-Prager yield criterion in compression. The reinforcing bars are modeled by a smeared layer at the location of reinforcements, and the steel layer model under Von Mises yield criteria is adopted to represent an elastic-plastic behavior. To investigate the dynamic response of a nuclear reinforced concrete containment structure, the steel-ratios of 0, 3, 5 and 10 percent, are considered. The results obtained from the analysis of an example were summarized as follows 1. As the steel-ratio increases, the amplitude and the period of the vertical displacements in apex of dome decreased. The Dynamic Magnification Factor(DMF) was some larger than that of the structure without steel. However, the regular trend was not found in the values of DMF. 2. The dynamic response of the vertical displacement and the radial displacement in the dome-wall junction were shown that the period of displacement in initial step decreased with the steel-ratio increases. Especially, the effect of the steel on the dynamic response of radial displacement disapeared almost. The values of DMF were 1.94, 2.5, 2.62 and 2.66, and the values increased with the steel-ratio. 3. The characteristics of the dynamic response of radial displacement in the mid-wall were similar to that of dome-wall junction. The values of DMF were 1.91, 2.11, 2.13 and 2.18, and the values increased with the steel-ratio. 4. The amplitude and the period of the hoop-stresses in the dome, the dome-wall junction, and the mid-wall were shown the decreased trend with the steel-ratio. The values of DMF were some larger than those of the structure without steel. However, the regular trend was not found in the values of DMF.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.352-358
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• 2014

The feasibility of perchlorate reducing-bacteria isolated from the sludge of an anaerobic digester was determined using ammonium perchlorate in aqueous medium. Growth kinetics of the two perchlorate reducing bacteria including Rhodococcus sp. YSPW01 and YSPW02 were investigated using acetate as the electron donor in batch experiment. The growth of YSPW01 and YSPW02 reached a steady-state at 26 and 9 h, respectively. The initial perchlorate concentration was completely reduced within 8 and 7 h by YSPW01 and YSPW02, respectively. The reduction rates were 2.1 and $15mg\;L^{-1}h^{-1}$ for YSPW01, and 3.2 and $15.5mg\;L^{-1}h^{-1}$ for YSPW02, at 1:1 and 5:1 ratios of acetate:perchlorate (w:w), respectively. In this study, the bacteria Rhodococcus sp. YSPW01 and YSPW02 demonstrated a potential for the perchlorate reduction, which could be further investigated for development of an efficient strategy to treat the perchlorate contaminated waters.

• Journal of Animal Science and Technology
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• v.44 no.3
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• pp.341-350
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• 2002

Twenty four Hanwoo bulls(mean initial body weight 162$\pm$8.1kg) were employed to induce the regression equations on body weight gain and dry matter intake. The diets were fed in a 3${\times}$4 factorial arrangement; three roughage sources(rice straw, hay, corn silage) and four roughage ratios in ration(100, 60, 40, 20%). Bulls were alloted by incomplete turn over design with four replications. Daily body weight gain was greatest in bulls fed the corn silage as a roughage source and the 20% of roughage ratio, respectively. Bulls fed hay or corn silage only as feed kept in their body weight gain during the whole experimental period, however those fed rice straw only were in a negative body gain hereafter fatteningⅠperiod(350kg of body wt.). Dry matter intake per metabolizable body weight was decreased with increasing body weight. Dry matter intake was greatest in bulls fed the corn silage as a roughage source and the 20% of roughage ratio, respectively. The regression equations on daily body weight gain(DG, kg) and dry matter intake(DMI, kg/day) according to body weight(BW, kg) of Hanwoo bulls were derived as follows; DG = －0.842 + 17.5DMI/$BWkg^{0.75}$ DMI = 4.125 + 0.013BW + 1.075DG － 0.045NDF where, NDF is the percentage of neutral detergent fiber in ration.

• The Korean Journal of Pesticide Science
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• v.13 no.1
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• pp.13-20
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• 2009

Two insecticides, commonly used for Chinese cabbage, etofenprox and methoxyfenozide, were subjected to a field residue trial to evaluate safeties of the residues at harvest. The pesticides were sprayed onto the crop at recommended and double doses 10 days before the prearranged harvest and then sampling was done at 0, 1, 2, 3, 5, 7, 10, and 12 days after spraying. The amounts of pesticides residues in the crop were analyzed by chromatographic methods. Limits of detection (LODs) of both etofenprox and methoxyfenozide were $0.01mg\;kg^{-1}$ and mean recoveries were $96.76{\pm}2.67$ (CV=2.76%) and $95.84{\pm}2.57%$(CV=2.69%) in case of etofenprox and $103.26{\pm}3.21$ (CV=3.11%) and $94.50{\pm}1.35%$(CV=1.43%) in case of methoxyfenozide, respectively. Biological half-lives of etofenprox and methoxyfenozide were 3.2 and 3.5 days at the recommended dose and 2.7 and 3.5 days at the double dose, respectively. Initial residue levels of the pesticides at the recommended and double doses exceeded their MRLs, but final residue levels of the pesticides in the crop samples at harvest were less than their MRLs. The ratios of the EDI to ADI by intake the crop harvested 10 days after spraying were less than 4% of their ADIs, representing that residue levels of two pesticides at harvest were evaluated as safe.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.5
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• pp.436-445
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• 1986

As the second part of the studies on the utilization of polyunsaturated lipids in sardine oil as nutritional or medical supplement, the conditions of lipid extration and concentration, refining, and storage stability of EPA-condensed sardine oil were investigated. In extraction of lipids, solvent ratios of chloroform-methanol mixture(2:1 v/v) affected the final content of unsaturated lipid in extracted oil and recovery. Stepwise solvent fractionation method at various low temperatures was effective to concentrate polyenoic acids like EPA and DHA when acetone or acetone-methanol mixture, added in the ratio of 1:5 (v/v) was applied step by step to different temperatures at 0 to $-35^{\circ}C$. Addition of 1 to $5\%$ (v/v) of water to acetone was also benefit to raise EPA content but that resulted in reducing the yield of condensed oil from $65\%\;to\;28\%$. Concentration rate of polyenoic acids by solvent fractionation in lipid-actone solution (1:5, v/v) at 0 to $-30^{\circ}C$ seemed limited to $5{\sim}8\%$ in fatty acid composition depending on the initial content of those polyenoic acids in the sardine oil. During the extraction, concentration, and alkaline treatment, oxidation was rapidly induced but oxidation products could be thoroughly removed on the process of deceleration and peroxide elimination. To stabilize the reactive polyenoic acid condensed oil during the storage, stuffing nitrogen gas was essential to expel dissolved oxygen in oil or to seal the oil from open air, and the addition of antioxidative agents as BHA and tocopherols were greatly helpful to extend the storage life.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.723-730
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• 2011

In this experiment, persulfate, a strong oxidant for ISCO (In-Situ Chemical Oxidation) was used to degraded RDX in artificial ground water at ambient temperature. Results of RDX degradation by persulfate in a batch reactor showed that the oxidation reaction was pseudo first order with estimated Ea (activation energy) of $1.14{\times}10^2kJ/mol$ and the rate was increased with the increase of reaction temperature. The oxidation of RDX by persulfate increased slightly with the increase of initial solution pH from 4 to 8. The RDX oxidation rate increased 13 times at pH 10 compared with that at pH 4, however, alkaline hydrolysis was found to be the main reaction of RDX degradation rather than oxidation. The study also showed that the oxidation rate of RDX by persulfate was linearly dependent upon the molar ratios of persulfate to RDX from 5 : 1 up to 100 : 1, with a proportion constant of $4{\times}10^{-4}$ ($min^{-1}$/molar ratio) at $70^{\circ}C$. While NOM (Natural Organic Matter) exerted negative effects on the oxidation rate of RDX by persulfate, with a proportion constant of $1.21{\times}10^{-4}$ ($min^{-1}{\cdot}L/mg-NOM$) at $70^{\circ}C$ and persulfate/NOM molar ratio of 10/1. The decrease in RDX oxidation rate was linearly dependent upon the added NOM concentration. However, the estimated activation energy in the presence of 20 mg-NOM/L was within 3.3% error compared to that without NOM, which implies the addition of NOM does not alter intrinsic oxidation reaction.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.237-246
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• 2008

The cross-sections of continuous multi-span beams sometimes suddenly increase, or become stepped, at the interior supports of continuous beams to resist high negative moments. The three-dimensional finite-element program ABAQUS (2006) was used to analytically investigate the inelastic lateral-torsional buckling behavior of stepped beams subjected to pure bending moment and resulted in the development of design equations. The flanges of the smaller cross-section were fixed at 30.48 by 2.54 cm, whereas the width and/or thickness of the flanges of the larger cross-section varied. The web thickness and height of beam was kept at 1.65 cm and 88.9 cm, respectively. The ratios of the flange thickness, flange width, and stepped length of beams are considered analytical parameters. Two groups of 27 cases and 35 cases, respectively, were analyzed for double and single stepped beams. The combined effects of residual stresses and geometrical imperfection on inelastic lateral-torsional buckling of beams are considered. First, the distributions of residual stress of the cross-section is same as shown in Pi, etc (1995), and the initial geometric imperfection of the beam is set by central displacement equal to 0.1% of the unbraced length of beam. The new proposed equations definitely improve current design methods for the inelastic LTB problem and increase efficiency in building and bridge design. The proposed solutions can be easily used to develop new design equation for inelastic LTB resistance of stepped beams subjected to general loading condition such as a concentrated load, a series of concentrated loads or uniformly distributed load.

• Journal of the Korean Geotechnical Society
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• v.31 no.8
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• pp.17-28
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• 2015

The purpose of this study is to measure the volumetric water content of unsaturated soils during drying and wetting process by using volumetric pressure plate extractor (VPPE) incorporated with time domain reflectometry (TDR). The VPPE consists of a pressure cell, a pressure regulator, a burette system and a TDR probe. Two samples with different initial void ratios were prepared in the pressure cell, and the air pressure at the range of 0.1 kPa - 50 kPa was applied to adjust the matric suction by the pressure regulator. The burette system was used to measure the volumetric water content change of the sample according to the matric suction. In addition, the TDR probe, installed in the cell, was used to evaluate the dielectric constant from the reflected signal of the electromagnetic wave at the probe. The volumetric water content of specimen was estimated by the empirical equation between the volumetric water content and dielectric constant, which was calibrated with the Jumunjin sand. The test results show that the volumetric water content calculated by TDR probe is strongly correlated to the measured value by burette system. The hysteresis occurs during drying and wetting process. Furthermore, the degree of hysteresis reduces in the repeated process. This study suggests that TDR may be effectively used to evaluate the water content soil for the determination of water characteristic curve of unsaturated soils.

• Journal of Life Science
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• v.20 no.10
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• pp.1427-1432
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• 2010

This study was carried out to evaluate neutralization effects against WSSV using antiserum produced from recombinant envelop protein, rVP466 of WSSV. The VP466 gene of WSSV was cloned into pCold I expression vector and rVP466 was expressed in E. coli RIPL. The antiserum against rVP466 was produced in white rabbits (New Zealand white rabbit). The specific immunoreactivity to the antigen, rVP466, was confirmed by Western blot. The constant amounts of WSSV at $1{\times}10^4$ diluted stocks were mixed with various antiserum concentrations and then injected to the muscle of shrimp, Penaeus chinensis, for the neutralization challenge. The shrimps challenged with WSSV as a positive control and those with the mixture of WSSV and preimmune serum as a preimmune control showed 100% cumulative mortality at 17 days post challenge and 83% at 25 days post challenge, respectively. The shrimps challenged with 3 different mixtures of WSSV and rVP466 antiserum at ratios of 1:0.01, 1:0.1 and 1:1 showed 73%, 53% and 46% cumulative mortalities at 25 days post challenge, respectively. These results indicated that WSSV could be neutralized by the rVP466 antiserum. These results suggest that envelop protein VP466 is involved in the initial step of WSSV infection in shrimp.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.3
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• pp.434-442
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• 2008

The objective of this study was to determine the optimum ratio of methionine to methionine plus cystine for growing pigs. A nitrogen balance trial was conducted using a total of 21 barrows (Large WhiteLandrace) over two replicates. The initial body weight was $20.36{\pm}1.22kg$ (mean${\pm}$SD) in the first replicate and $23.54{\pm}1.02kg$ (mean${\pm}$SD) in the second. For each replicate, the 21 pigs were randomly assigned to one of seven dietary treatments with three observations per treatment. The diets included a methionine and cystine-deficient basal diet with all other essential nutrients meeting nutrient requirements and six diets formulated with graded levels of DL-methionine (0.00, 0.03, 0.06, 0.10, 0.13, 0.16%) and $L-Cystine{\cdot}HCl{\cdot}H_2O$ (0.19, 0.15, 0.11, 0.07, 0.04, 0.00%). This resulted in ratios of methionine to methionine plus cystine of 41.3, 29.6, 35.3, 41.2, 46.0, 51.6 and 57.5%. Each experimental period lasted 12 days consisting of a seven-day adaptation period followed by a five-day total collection of urine and feces. During the collection period, pigs were fed 900 g/day for the first replicate and 1,200 g/day for the second replicate. The feed was provided in three equal portions at 0800, 1500, and 2200 h daily. Pigs had ad libitum access to water after feeding. There was a linear (p<0.01) and quadratic (p<0.01) effect on daily gain and feed conversion as the ratio of methionine to methionine plus cystine increased. Pigs receiving the diets providing a methionine to methionine plus cystine ratio of 51.6% had the best daily gain and feed conversion. Plasma urea nitrogen was also lowest for this treatment. Nitrogen retention increased (p<0.01) as the relative proportion of methionine increased up to 51.6% and then a downward trend occurred at 57.5%. The quadratic regression model, as well as one- and two- slope regression line models, were used to determine the optimum ratio of methionine to methionine plus cystine. Eliminating the 35.3% methionine to methionine plus cystine treatment resulted in $R^2$ values in excess of 0.92. The optimal ratio of methionine to methionine plus cystine was estimated to be 54.15% for nitrogen retention and 56.72% for plasma urea nitrogen.