• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.795-799
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• 1995

The magnetostriction versus field (${\lambda}-H$) curves for the melt-spun ribbons of $Dy_{x}{(Fe_{1-y}B_{y})}_{1-x}$ (x=0.2, 0.25, 0.3; y=0, 0.05, 0.1, 0.15, 0.2) alloys are measured systematically at various wheel speeds ranging from 10 to 50 m/sec. The ${\lambda}-H$ curves in most cases vary sensitively with the wheel speed and, in the wheel speed range where no amorphous phase is formed, the magnetic softness improves rather continuously with the wheel speed. This result is considered to be due to the reduced grain size with increasing wheel speed, which was confirmed by X-ray diffraction and transmission electron microscopy. In particular, homogeneous and ultrafine grains with size of about 10 nm are formed even in the as-spun state when the $Dy_{0.3}{(Fe_{1-y}B_{y})}_{0.7}$ alloys are quenched at the wheel speed of 30 m/sec (for the alloy with y=0.2) or 40 m/sec (for the alloys with $y{\leq}0.15$) and the ribbons having the nanocrystalline grain structure exhibit good magnetostrictive characteristics.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.4
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• pp.201-207
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• 1979

The stow net now used in the Yellow Sea, are traditional bag net with the opening held by a lighter upper and a weighted lower beams standing against the current. Such bag net anchored at the bottom are known in many countries, particularly in the estuaries of large rivers, but more rarely in sea fisheries, because they are too much affected by the weather, moreover a permanent strong current is necessary. Some scientists intended to improve this fishing gear, using the shearing devices instead of a lighter upper and a weighted lower beams in order to widen mouth of the stow net however they are unsuccessful. One-fortieth scale model net of the stow net was tested in a circular water tank with an effective volume of $5.67m\times1.76m\times1.00m$ of observing the configuration and tension of the net. Experiments were carried out under the various combination including water velocity, spherical floats and elevating floats with the shearing hoods instead of the upper beam. We found those devices offered a very low resistance per net area to current compared with the spherical floats or upper beam, and had a fairly good shearing power at any velocity and direction of the current. The total resistance (R) of the model net to which shearing hoods and floats are attached can be induced by the following formula under the condition of 0.25m/sec to 0.5m/sec, $$R(kg)=3.11V^{1.54}$$ The height (h) of the improved model net (m-B) is higher than traditional model net(m-A) with upper and lower beams, m-A: h(cm)=89.22-2.42(V-15). $V\geqq15,\;cm/sec$ m-B: h(cm)=89.20-0.78V (V:cm/sec) The catch efficiency of improved model net is 1.5 times traditional model net.

• Korean Journal of Veterinary Research
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• v.41 no.2
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• pp.177-188
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• 2001

Mastitis is one of the most significant cause of economic loss to the dairy industry. Especially, Staphylococcus aureus is a major contagious mastitis-causing pathogen in dairy cattle. Because of its high transmission rate and resistance to antibiotic therapy, staphylococcal mastitis presents a constant threat to the dairy industry. Staphylococcal enterotoxin C(SEC) produced by S aureus has been known as one of superantigens which are able to stimulate a large proportion of T lymphocytes independently of their antigenic specificity. In this experiment, we have conducted preliminary studies with mice and lactating cows to evaluate the immunogenicity and safety of the experimental vaccine consists of SEC mutant antigen on controlling the bovine mastitis associated with S aureus infections. The average value of somatic cell counts in quarter milk, isolation rate of S aureus were consistently decreased in SEC-SER vaccinated groups, whereas antibody titers were highly increased in SEC-SER vaccinated groups. Peripheral blood were also collected from the lactating cows to determine the proportion of leukocyte subpopulation associated with humoral immunity(HI) and cell mediated immunity(CMI). Proportion of leukocyte subpopulation expressing $BoCD2^+$(total T lymphocyte), $BoCD4^+$(T helper cell), $BoCD8^+$(T cytotoxic/suppressor cell) and NonT/NonB lymphocyte which are involved in CMI in SEC-SER vaccinated groups were decreased for the initial stage after first vaccination and then increased from ten weeks after first vaccination maintaining elevated level till 14 weeks after vaccination. In contrast, proportion of monocyte, MHC class II and B lymphocyte which are associated with the production of primary immune response in SEC-SER vaccinated groups were increased for the initial period and then decreased from ten weeks after first vaccination. We present evidence that vaccination of SEC-SER mutant antigen in lactating cows induced a significant proliferation of bovine T lymphocytes. These results suggest that SEC-SER mutant antigen used in this experiment might be one of potential immunogen in developing innovative vaccine against bovine IMI associated with S aureus. Additional challenge trials should be carried out to evaluate substantial protection against S aureus under the commercial farm conditions.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.203-212
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• 2010

The aim in this study is used to develop the remediation technologies for contaminated ground water. Slug, single well pumping and step-drawdown tests have been used to obtain hydraulic parameter estimates in the field. Slug tests yield hydraulic conductivity values using the Bouwer and Rice and C-B-P analysis methods. The mean and median hydraulic conductivity values of Bouwer and Rice method are $4.48{\times}10^{-3}$ and $1.16{\times}10^{-3}cm/sec$, respectively. On the other hand, C-B-P method gave mean and median hydraulic conductivity values of $2.37{\times}10^{-3}$ and $7.09{\times}10^{-4}cm/sec$, respectively. These analyses show a trend for the Bouwer and Rice method to yield lower hydraulic conductivity values in low permeability zones of granite in the study area. Sing well pumping test data were calculated through type curve in GW7, GW12 and MW9 wells. It could be interpreted that the differences of hydraulic conductivity and transmissivity values between GW7 and GW12, MW9 is related with fault clays and fractures in the bedrock among the wells. Step-drawdown tests were carried out in the KDPW1 and KDPW2 wells. The hydraulic parameter of KDPW1 and KDPW2 showed very litter difference between the values. The study of hydraulic parameter estimates can be used to purify in contaminated groundwater.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.267-273
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• 2006

This paper improves the effects of clustered OFCDM scheme considering the frequency diversity effect over a frequency selective fading channel. In OFCDM with frequency domain spreading compared to OFDM, we can increase uncorrelated symbols by frequency allocation method of correspondent symbols over the same antenna and different antenna after spreading. The simulation results show that the performance of proposed system is improved by approximately 4 dB in ${\sigma}=0.02{\mu}sec$, the performance is improved by approximately 2.5dB in large delay spread in a 12-path Rayleigh fading channel with overall the root mean squared delay spread and the maximum Doppler frequency of 20 Hz. Also, the required average received Eb/No at the average BER of $10^{-3}$ by optimum method is improved by approximately 2.0 dB, compared to that of STA-OFCDM with frequency rearrange. The new method does not require any bandwidth expansion any feedback from the receiver to the transmitter and its computation complexity is similar to clustered OFCDM.

• Food Science and Preservation
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• v.4 no.2
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• pp.189-196
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• 1997

Blanching conditions for immatured soybeans were optimized by analyzing the effects of various time/temperature blanch treatment on the activities of peroxidase and lipoxygenase, the stability of vitamin C and color, and moisture content in immatured soybeans for the purpose of minimizing quality deterioration during frozen storage. Blanching at 96$^{\circ}C$ for 70 sec led to maximum inactivation of lipoxygenase in the immatured soybeans, while my blanching conditions tested in this study were not enough to inactivate peroxidase. Blanching at 82$^{\circ}C$ for 60 sec resulted in the highest amount of vitamin C remaining in the immatured soybeans after blanching. Hunter -a/b ratios of immatured soybeans blanched at 82$^{\circ}C$ for 60 sec and hue values (ΔE) of the immatured soybeans blanched at 76$^{\circ}C$ for 60 sec showed the closest values to those of fresh products. The changes in moisture content of immatures soybeans was not so significant after blanching. In conclusion, it was suggested that immatured soybeans be blanched at 96$^{\circ}C$ for 70 sec to minimize lipoxygenase activity and resulting quality deterioration, while blanching at 82$^{\circ}C$ for 60 sec was recommended to stabilize vitamin C and color.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.6
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• pp.593-601
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• 2021

Primary cilia on kidney tubular cells play crucial roles in maintaining structure and physiological function. Emerging evidence indicates that the absence of primary cilia, and their length, are associated with kidney diseases. The length of primary cilia in kidney tubular epithelial cells depends, at least in part, on oxidative stress and extracellular signal-regulated kinase 1/2 (ERK) activation. Hydrogen sulfide (H₂S) is involved in antioxidant systems and the ERK signaling pathway. Therefore, in this study, we investigated the role of H₂S in primary cilia elongation and the downstream pathway. In cultured Madin-Darby Canine Kidney cells, the length of primary cilia gradually increased up to 4 days after the cells were grown to confluent monolayers. In addition, the expression of H₂S-producing enzyme increased concomitantly with primary cilia length. Treatment with NaHS, an exogenous H₂S donor, accelerated the elongation of primary cilia whereas DL-propargylglycine (a cystathionine γ-lyase inhibitor) and hydroxylamine (a cystathionine-β-synthase inhibitor) delayed their elongation. NaHS treatment increased ERK activation and Sec10 and Arl13b protein expression, both of which are involved in cilia formation and elongation. Treatment with U0126, an ERK inhibitor, delayed elongation of primary cilia and blocked the effect of NaHS-mediated primary cilia elongation and Sec10 and Arl13b upregulation. Finally, we also found that H₂S accelerated primary cilia elongation after ischemic kidney injury. These results indicate that H₂S lengthens primary cilia through ERK activation and a consequent increase in Sec10 and Arl13b expression, suggesting that H₂S and its downstream targets could be novel molecular targets for regulating primary cilia.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.246-249
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• 2007

This study is concerned with deep drawability of magnesium sheets(AZ31B) at the warm conditions. Especially the dependency on forming speed has been investigated at the temperature of $200^{\circ}C$ and $300^{\circ}C$. Deep drawing test has been carried out at the temperature of $200^{\circ}C$ and $300^{\circ}C$. The die and blank holder are kept at test temperature by local heating and the punch is kept at room temperature by cooling technique. The magnesium sheets called AZ31B with the thickness of 0.5mm have been applied to deep drawing of circular cup. The drawability has been estimated at the conditions of forming speed (0.1, 1, 10 mm/sec). The results of deep drawing experiments show that the drawability is better at $300^{\circ}C$. Also the deep drawability is improved at the low speed(1mm/sec).

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.7-14
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• 1999

TiZrB2 solid solution was synthesized using fine powders of Ti, Zr and B by SHS microwave process. The characterization of the synthesized powder and sintered bodies ws investigated. The combustion temperature and rate were increased with increasing the mole ratio of Zr in temperature profile, and showed the maximum combustion temperature and velocity values of 285$0^{\circ}C$ and 14.6mm/sec in Ti0.2Zr0.8B2 composition. Phase separation has been occured into a composite with TiB2 and ZrB2 phases from TiZrB2 solid solution, which was hot pressed sintering at 30 MPa for an hour at 190$0^{\circ}C$. At the composition of Ti0.8Zr0.2B2 the best properties has been obtained in relative density, bending strength, fracture toughness and hardness, with 99%, 680 MPa, 7.3MPa.m1/2 and 2750 Kg/$\textrm{mm}^2$ respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.1
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• pp.1-10
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• 1982

Diffusion processes in tidal swinging coastal waters are studied by releasing one hundred liters of Rhodamine B four times. Dye patches were formed from instantaneous point sources. The patches were sampled with a pump on a tracking boat, and samples were analyzed with fluorospectro-photometer. The patterns of patches were reconstructed and their characteristics were analyzed in terms of variance of concentration, area estimation, and decrease rate of peak concentration. In all of the four experiments, the dye patches were mos시 elongated to the direction of current axis. the elongation rate was 0.34 on the average. Apparent diffusivities were 620 to 3,000 cm super(2) /sec during initial period of 90 minutes. The variance increased by exp(0.047t) on the average, and peak concentration deceased by exp(-0.044t) on the average.