• Journal of Radiation Protection and Research
• /
• v.41 no.3
• /
• pp.260-267
• /
• 2016

Background: This study analyzes the differences in the annual averaged atmospheric dispersion factor and ground deposition factor produced using two classification methods of atmospheric stability, which are based on a vertical temperature difference and the standard deviation of horizontal wind direction fluctuation. Materials and Methods: Daedeok and Wolsong nuclear sites were chosen for an assessment, and the meteorological data at 10 m were applied to the evaluation of atmospheric stability. The XOQDOQ software program was used to calculate atmospheric dispersion factors and ground deposition factors. The calculated distances were chosen at 400 m, 800 m, 1,200 m, 1,600 m, 2,400 m, and 3,200 m away from the radioactive material release points. Results and Discussion: All of the atmospheric dispersion factors generated using the atmospheric stability based on the vertical temperature difference were shown to be higher than those from the standard deviation of horizontal wind direction fluctuation. On the other hand, the ground deposition factors were shown to be same regardless of the classification method, as they were based on the graph obtained from empirical data presented in the Nuclear Regulatory Commission's Regulatory Guide 1.111, which is unrelated to the atmospheric stability for the ground level release. Conclusion: These results are based on the meteorological data collected over the course of one year at the specified sites; however, the classification method of atmospheric stability using the vertical temperature difference is expected to be more conservative.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.450-452
• /
• 2004

Using factor analysis and bivariate comparisons of major components in ground water, three geochemical processes were identified as controlling factors of ground water chemistry; 1) natural mineralization by water rock interactions, 2) effect of seawater which includes salinization by seawater near seashores and deposition of sea salt, and 3) nitrate contamination by N fertilization. Contribution of rainfall was also estimated from the measured composition of wet deposition. The geochemical processes were separated using total alkalinity as an indicator for natural mineralization, Cl for effect of seawater, and nitrate for N fertilization. Relatively high correlation of major components with nitrate suggests that nitrification of nitrogenous fertilizers significantly affects ground water chemistry. Total cations derived from nitrate sources have good linearity for nitrate in equivalent basis with a slope of 1.8, which is a mean of proton production coefficients in nitrification of two major compounds in nitrogenous fertilizers, ammonium and urea. Contribution of nitrate sources to base cations, Cl, and SO$_4$ in ground water was determined considering maximum contribution of natural mineralization to estimate a threshold of the effect of N fertilization for ground water chemistry, which shows W fertilization has a greatest effect than any other processes in ground water with nitrate concentration greater than 50 mg/L for Ca, Mg, Na and with concentration greater than 30 mg/L for Cl and SO$_4$.

• Steel and Composite Structures
• /
• v.33 no.6
• /
• pp.767-776
• /
• 2019

In this article, a simple and robust multi-objective assessment method to control design angles and node positions connected among steel outrigger truss members is proposed to approve both structural safety and economical cost. For given outrigger member layouts, the present method utilizes general-purpose prototypes of outrigger members, having resistance to withstand lateral load effects directly applied to tall buildings, which conform to variable connecting node and design space deposition. Outrigger layouts are set into several initial design conditions of height to width of an arbitrary given design space, i.e., variable design space. And then they are assessed in terms of a proposed multi-objective function optimizing both minimal total displacement and material quantity subjected to design impact factor indicating the importance of objectives. To evaluate the proposed multi-objective function, an analysis model uses a modified Maxwell-Mohr method, and an optimization model is defined by a ground structure assuming arbitrary discrete straight members. It provides a new robust assessment model from a local design point of view, as it may produce specific optimal prototypes of outrigger layouts corresponding to arbitrary height and width ratio of design space. Numerical examples verify the validity and robustness of the present assessment method for controlling prototypes of outrigger truss members considering a multi-objective optimization achieving structural safety and material cost.

• Journal of Radiation Protection and Research
• /
• v.29 no.2
• /
• pp.91-96
• /
• 2004

A practical methodology for the determination of derived intervention levels (DILs) on relocation following an accidental release of radionuclides was designed based on dose rate on the ground. The influence of DILs was investigated with respect to the change of parameter values, which are dependent on socio-environmental characteristics in distinction from temporary and permanent relocations. The DILs on relocation showed a distinct difference depending on effective removal half-life of radionuclides following a deposition, delay time in measurement and residential characteristics. In particular, the delay time. In measurement was an important factor in determination of DILs in the case of an assumption that dose rate on the ground declines in a power function, not in an exponential function. The DILs showed lower numerical values as longer effective half-life, longer delay time In measurement and longer exposure time.

• Advances in environmental research
• /
• v.3 no.1
• /
• pp.71-86
• /
• 2014

Macronutrients ($Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$), yield and yield components, bioaccumulation and translocation of metal in plant parts of three Vigna species (V. cylindrica, V. mungo, V. radiata) were evaluated at 0, 50, 100 and $150mgkg^{-1}$ soil of Nickel (Ni). A marked inhibition (p < 0.001) in the distribution of various macronutrients was noticed in these Vigna species except for $Mg^{2+}$ content of the shoot and leaves. Similarly, all species retained more $Ca^{2+}$ in their roots (p < 0.05) as compared to the aerial tissues. Ni induced a drastic decline (p < 0.001) for various yield and yield attributes except for 100 seed weight. Toxicity and accumulation of Ni in plant tissues considerably increased in a concentration dependent manner. Vigna species signify an exclusion approach for Ni tolerance as both bioaccumulation factor (BF) and translocation factor (TF) were less than 1.0. The Ni content of plants being root > shoot > leaves > seeds. Scoring for percentage stimulation and inhibition (respective to control) at varying levels of Ni revealed tolerance of the species in an order of V. radiata > V. cylindrica > V. mungo. The acquisition of Ni tolerance in V. radiata seems to occur through an integrated mechanism of metal tolerance that includes sustainable macronutrients uptake, stronger roots due to greater deposition of $Ca^{2+}$in the roots, restricted transfer of Ni to above ground tissues and seeds as well as exclusion capacity of the roots to bind appreciable amount of metal to them. Thus, metal tolerant potential of V. radiata could be of great significance to remediate metal contaminated soil owing lesser impact of Ni on macro-nutrients, hence the yield.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.6
• /
• pp.95-107
• /
• 2004

In this paper, the rheological characteristics of slurry used fur slurry-shield tunnels were studied with emphasis on penetration characteristics. The slurry penetration was modeled by soil-filter clogging theory. The coefficient of particle deposition was suggested as an indicator of sin clogging during tunnel construction and calculated through model tests. The measured slurry weight, clogged in the base soil, was compared with the value obtained from clogging theory. Based on the testing results, a stability analysis of a tunnel face was performed to pinpoint the most influential factor affecting stability of slurry-shield tunnels. It was found that the stability of tunnel face is dependent on the ratio of infiltration velocity to the coefficient of particle deposition, and the penetration distance of slurry increases with the ratio of infiltration velocity to the coefficient of particle deposition. Since the stability of tunnel face decreases with the slurry penetration distance, it was necessary to add some additives in order to reduce the slurry penetration distance. It was found that the ground condition needs additives when the soil has the effective particle diameter$(D_{10})$ larger than 0.75mm. It was also found that the tunnel face stability due to slurry penetration is significantly affected by the tunnel advance rate.

• Korean Journal of Materials Research
• /
• v.10 no.8
• /
• pp.575-580
• /
• 2000

Diamond thin films were deposited on $Si_3N_4$, SiC, TiC and $Al_2O_3$, substrates by the CVD method using Ta(TaC)Filament, and the appearance of the diamond films and their adhesion properties were examined by SEM, optical microscopy, indentation test and compression topple test. Diamond films were deposited at lower $CH_4$ concentration than 5%$CH_4$ for all kinds of the substrate material, but graphitic(amorphous)carbon was observed at 10%$CH_4$. The diamond film of about $12\mu\textrm{m}$ thickness on WC substrate partly peeled off, but the film on $Si_3N_4$ substrate held good adhesion. The indentation test showed that roughly ground surface was very effective for adhesion of diamond films to substrate. The topple test revealed that film thickness was an important factor governing the adhesion of the diamond film.

• Journal of Radiation Protection and Research
• /
• v.28 no.4
• /
• pp.299-309
• /
• 2003

In an accidental release of radioactive materials to the environment the contaminative influence of animal products due to the inhalation of air and the ingestion of soil of livestock, both of which are dealt with as minor contaminative pathways in most radioecological models but may not be neglected, was investigated with the improvement of the Korean dynamic food chain model DYNACON Although mathematical models for both contaminative pathways have been established for considering all animal products and incorporated into the model, investigation was limited to milk. As a result, it was found that both pathways are influential in the contamination of milk in the case of an accidental release during the non-grazing period of dairy cows. In the case of an accidental release during the non-grazing period, the inhalation of air was more influential than the ingestion of soil in the early days following an accidental release. While, it was the opposite with the lapse of time. If precipitation is encountered during an accidental release, contaminative influence due to the ingestion of soil was greater compared with the cases of no precipitation, in general, because of a stealer deposition of radionuclides onto the ground. Precipitation during an accidental release was a less influential factor in $^{131}I$ (elemental iodine) contamination compared with the $^{137}Cs\;and\;^{90}Sr$ contaminations. In the case of an accidental release during the grazing period of dairy cows, the contaminative influence due to the inhalation of air was negligible.