• Journal of Electrochemical Science and Technology
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• v.8 no.3
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• pp.197-205
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• 2017

Lead dioxide thin films were electrodeposited on nickel substrate from acidic lead nitrate solution. Current efficiency and thickness measurements, cyclic voltammetry, AFM, SEM, and X-ray diffraction experiments were conducted on $PbO_2$ surface to elucidate the effect of lead nitrate concentration, current density, temperature on the morphology, chemical behavior, and crystal structure. Experimental results showed that deposition efficiency was affected by the current density and solution concentration. The film thickness was independent of current density when deposition from high $Pb(NO_3)_2$ concentration, while it decreased for low concentration and high current density deposition. On the other hand, deposition temperature had negative effect on current efficiency more for lower current density deposition. Cyclic voltammetric study revealed that comparatively more ${\beta}-PbO_2$ produced compact deposits when deposition was carried out from high $Pb(NO_3)_2$ concentration. Such compact films gave lower charge discharge current density during cycling. SEM and AFM studies showed that deposition of regular-size sharp-edge grains occurred for all deposition conditions. The grain size for high temperature and low concentration $Pb(NO_3)_2$ deposition was bigger than from low temperature and high concentration deposition conditions. While cycling converted all grains into loosely adhered flappy deposit with numerous pores. X-ray diffraction measurement indicates that high concentration, high temperature, and high current density favored ${\beta}-PbO_2$ deposition while ${\alpha}-PbO_2$ converted to ${\beta}-PbO_2$ together with some unconverted $PbSO_4$ during cycling in $H_2SO_4$.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.1
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• pp.49-54
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• 1998

This experiment was carried out to investigate effect of plant density on yield and quality of corn at the forage experimental field, grassland and forage division, National Livestock Research Institute, RDA, Suwon eom 1996 to 1997. The two corn hybrids, P 3352 and G 4743, were grow at plant density of 67,000; 71,000; 83,000 ; 89,000 and 95,000 plantha in 60,70 and 75-an spaced rows. At the low density, plant and ear height were decreased but ear length and weight were increased. Plant density had little effect on the tasseling date, silking date and ear ratio to total dry matter. The total dry matter yield of two hybrids was increased kom 15,294 to 18,996 in P 3352 hybrid and 15,881 to 21,386kglha in G 4743, respectively, by decreasing plant density. Plant density had little effect on the ADF(acid detergent fiber), NDF (neutral detergent fiber) and CP(crude protein) concentrations, but the quality of late maturity hybrid, G 4743, was higher than that of early maturity hybrid, P 3352. The result of this study indicate that 67,000 plantlha plant density was recommendable for machanization and maximum DM yield of corn.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.181-181
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• 2012

The microwave probe for measuring plasma density is widely used for its advantages: First, it is not affected by the reactive gas. Second, it can measure local plasma parameters such as plasma density, plasma potential and plasma temperature. Third, it is simple and robust. A cut-off probe is the one of the most promising microwave probe. Recently, Kim et al. reveals the physics of the cut-off probe but the effect of the sheath on the determination of the plasma density is not explained. In this presentation, for taking account of sheath effects on determination of plasma density from the cut-off peak, a simplified circuit modeling and an E/M simulation are conducted. The results show that occupation ratio of sheath volume between two tips of the cut-off probe and subsequence pressure condition mainly change position of the cut-off peak with respect to plasma frequency. Magnitude of relative voltage taken on the impedance of sheath and the impedance of bulk plasma can explain this effect. Furthermore, effects of gap size, tip radius, and tip length ware revealed based on above analysis.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.42-47
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• 2009

The propagation of an intense laser pulse through an upward density-gradient plasma in a self-modulated laser wakefield acceleration (SM-LWFA) is investigated by using particle-in-cell (PIC) simulations. In the fully relativistic and kinetic PIC simulations, the relativistic and kinetic effects including Landau damping enhance the electron dephasing. This electron dephasing is the most important factor for limiting the energy of accelerated electrons. However, the electron dephasing, which is enhanced by relativistic and kinetic effects in the homogeneous plasma, can be forestalled through the detuning process arising from the longitudinal density gradient. Simulation results show that the detuning process can effectively maintain the coherence of the laser wake wave in the spatiotemporal wakefield pattern, hence considerable energy enhancement is achievable. The spatiotemporal profiles are analyzed for the detailed study on the relativistic and kinetic effects. In this paper, the optimum slope of the density gradient for increasing electron energy is presented for various laser intensities.

• Proceedings of the Korean Nutrition Society Conference
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• 1994.05a
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• pp.45-45
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• 1994

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5229-5232
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• 2014

Background: While many studies have concluded that local traffic density is positively associated with childhood leukemia, the results are inconsistent. We therefore performed a meta-analysis to assess the relationship between traffic density and the risk of childhood leukemia. Methods: A systematic literature review was carried out using PubMed, EMBASE, and the Cochrane Library from January 1979 to December 2013. We selected and assessed journal articles evaluating the relationship between local traffic density and the risk of leukemia in children. The analysis was carried out using STATA version 12.0. Results: A total of 11 articles, including 12 estimates of effect, were included in our meta-analysis. The summary effect size from the random-effects model, expressed as an odds ratio, was 1.03 (95% CI: 0.98-1.09, p=0.002). No significant association between traffic density and the risk of childhood leukemia was found. Similar conclusions were found on subgroup analysis. Conclusions: The results of our meta-analysis suggested no association between traffic density and the risk of childhood leukemia. This implies that living in close proximity to roads with heavy traffic may not increase the risk of childhood leukemia. However, further high-quality prospective trials are needed to support these results.

• Journal of Korea Foundry Society
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• v.22 no.6
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• pp.309-314
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• 2002

The effect of mold density and evacuation on surface defect of high chromium cast iron upon EPC process was investigated. Under evacuation of $0.1{\sim}0.3$ atm, surface defects were carbon defect, burn on and misrun. Carbon defect was augmented by increasing mold density from 0.011 g/$cm^3$ to 0.03 g/$cm^3$ under evacuation of $0.1{\sim}0.3$ atm, but carbon defect was decreased by increasing evacuation from 0.1 to 0.3 atm. Burn-on wasn't found under evacuation of 0.1 atm regardless of mold density, but burn-on was augmented by increasing evacuation from 0.2 to 0.3 atm and decreased by reducing mold density. Misrun was only found under 0.1 atm evacuation and 0.011 g/$cm^3$ mold density.

• Corrosion Science and Technology
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• v.21 no.5
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• pp.348-359
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• 2022

Interest in electric vehicle is on the rise due to global eco-friendly policies. To improve the efficiency of electric vehicles, it is essential to reduce weights of components. Since electric vehicles have various electronic equipment, the research on stray current corrosion is required. In this research, a galvanostatic corrosion experiment was performed on 6061-T6 Al alloy for electric vehicle battery housing using chloride concentration and applied current density as variables in a solution simulating an acid rain environment. As a result of the experiment, when chloride concentration and applied current density were increased, corrosion damage became larger. In particular, pitting damage was dominant at an applied current density of 0.1 mA/cm². Pitting damage over the entire surface was found at a current density of 1.0 mA/cm². In conclusion, chloride concentration had a relatively large effect on localized corrosion. The applied current density had a great effect on uniform corrosion. However, in the case of applied current density, localized corrosion was also greatly affected by interaction with chloride.

• 전기의세계
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• v.23 no.4
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• pp.39-45
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• 1974

In most previous research work, the transverse edge effect has been allowed for only by use of a relativity-increase factor. This paper gives a more exact treatment. A two-dimensional-field analysis is presented for the problem of sheet rotor linear induction motor with finite width the method used takes account of flux leakage in the space between the stator and secondary sheet rotor as well as in the secondary itself. Equations are derived for the flux density distribution in the air gap and for the starting face, in each case as a function of stator current. The cross gap flux density peaks towards athe edge of the stator. This phenomena is known as the transverse edge effect. Measurements of the flux density in the air gap and starting force on a linear induction motor with sheet rotor of different width showed a reasonable agreement,suggest that it would be desirable to take into account also, at least for this motor in which severe redistribution occurs.

• Journal of Preventive Medicine and Public Health
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• v.49 no.6
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• pp.367-375
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• 2016

Objectives: The established theory that breast density is an independent predictor of breast cancer risk is based on studies targeting white women in the West. More Asian women than Western women have dense breasts, but the incidence of breast cancer is lower among Asian women. This meta-analysis investigated the association between breast density in mammography and breast cancer risk in Asian women. Methods: PubMed and Scopus were searched, and the final date of publication was set as December 31, 2015. The effect size in each article was calculated using the interval-collapse method. Summary effect sizes (sESs) and 95% confidence intervals (CIs) were calculated by conducting a meta-analysis applying a random effect model. To investigate the dose-response relationship, random effect dose-response meta-regression (RE-DRMR) was conducted. Results: Six analytical epidemiology studies in total were selected, including one cohort study and five case-control studies. A total of 17 datasets were constructed by type of breast density index and menopausal status. In analyzing the subgroups of premenopausal vs. postmenopausal women, the percent density (PD) index was confirmed to be associated with a significantly elevated risk for breast cancer (sES, 2.21; 95% CI, 1.52 to 3.21; $I^2=50.0%$). The RE-DRMR results showed that the risk of breast cancer increased 1.73 times for each 25% increase in PD in postmenopausal women (95% CI, 1.20 to 2.47). Conclusions: In Asian women, breast cancer risk increased with breast density measured using the PD index, regardless of menopausal status. We propose the further development of a breast cancer risk prediction model based on the application of PD in Asian women.