• Journal of the Korean Mathematical Society
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• v.44 no.4
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• pp.845-854
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• 2007

In this paper we investigate relationships between closure-type and convergence-type properties of hyperspaces over a space X and covering properties of X.

• Journal of Radiation Protection and Research
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• v.28 no.1
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• pp.19-24
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• 2003

The self-attenuation factor for an $^{198}Au$ sample and the 0.412 MeV gamma-ray penetration ratio in the circular Al-cover of the radiation detector have been determined using an analytical solution and MCNP code. The results show that the self-attenuation factors obtained from the analytical solution coincide with those of MCNP code for all but the Au sample with the relatively larger radius. Then the maximum difference between the two methods appears to be 9 % in the Au sample of 1.5 mm radius. It also is revealed that the analytical solutions of the 0.412 MeV gamma-ray penetration ratio in the Al-cover of 7.62 cm radius are consistent with those of the MCNP code within the standard deviation.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.319-336
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• 2015

Life cycle performance of corrosion affected RC structures is an important and challenging issue for effective infrastructure management. The accurate condition assessment of corroded RC structures mainly depends on the effective evaluation of deterioration occurring in the structures. Structural performance deterioration caused by reinforcement corrosion is a complex phenomenon which is generally uncertain and non-decreasing. Therefore, a stochastic modelling such as the gamma process can be an effective tool to consider the temporal uncertainty associated with performance deterioration. This paper presents a time-dependent reliability analysis of corrosion affected RC structures associated bond strength degradation. Initially, an analytical model to evaluate cracking in the concrete cover and the associated loss of bond between the corroded steel and the surrounding cracked concrete is developed. The analytical results of cover surface cracking and bond strength deterioration are examined by experimental data available. Then the verified analytical results are used for the stochastic deterioration modelling, presented here as gamma process. The application of the proposed approach is illustrated with a numerical example. The results from the illustrative example show that the proposed approach is capable of assessing performance of the bond strength of concrete structures affected by reinforcement corrosion during their lifecycle.

• Korean Journal of Agricultural Science
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• v.12 no.1
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• pp.108-117
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• 1985

The process of conveying of soil with the open auger to cover the seed completly with less power was reviewed by theoretical analysis. The power efficiency, the reasonable range of RPM of the open auger and the velocity of soil conveying to the direction of the shaft are examined to establish the extent of characteristics of the open auger performance. The results of theoretical analysis and application of similitude are as follows: 1. It is possible to predict the power efficiency by the following equation; ${\eta}_p={\frac{P_n}{P_g}}=({\frac{{\omega}_s}{{\omega}_a}}){\cdot}tan{\gamma}{\frac{mg}{(F_mcos{\alpha}+F_scos{\gamma})}}$ 2. The reasonable range of the revolutions per minute of the open auger was presented as follow to cover completely with less power ; $$\frac{4d(L_a-L_i){\cdot}V_w}{{\pi}(D_o^2-D_s^2){\cdot}r{\cdot}{\frac{{\omega}_s}{{\omega}_a}}{\cdot}tan{\gamma}}{{\leq_-}}{\omega}_a{{\leq_-}}({\frac{{\omega}_a}{{\omega}_s}}){\sqrt{\frac{g}{r}}}$$ 3. The velocity of soil conveying to the direction of the auger shaft may be calculated by the equation; $V_h=({\frac{{\omega}_s}{{\omega}_s}})V_a{\cdot}tan{\gamma}$ 4. The factor of RPM was more important than other factors on the power efficiency.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.2
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• pp.57-65
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• 2009

In continuous review inventory model, (${\varrho}$, ${\gamma}$) system, order quantity(${\varrho}$) and reorder point(${\gamma}$) should be determined to calculate inventory-related cost that consists of setup, holding, and penalty costs. The procedure to obtain the exact value of ${\varrho}$ and ${\gamma}$ is complex. In this paper, a regression analysis is proposed to get the approximate inventory-related cost without the determination of ${\varrho}$ and ${\gamma}$ in the case that the standard deviation(${\sigma}$) of the lead time demand is small or that the mean(${\mu}$) of the lead time demand is proportional to ${\sigma}$. To save inventory-related cost, central warehouses with (${\varrho}$, ${\gamma}$) system can be built. Central warehouse can provide some stores with products with the consideration of the tradeoff between inventory-related cost and transportation cost. The number and the location of central warehouses to cover all the stores are determined by a regression-based approach. The performance of the proposed approach is tested by using some computational experiments.

• The Journal of the Petrological Society of Korea
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• v.24 no.1
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• pp.11-24
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• 2015

In this study, the stone used for three storied pagoda of Bulguksa Temple, which is easy to access due to works for dismantle and restore will be analyzed on the basis of petrographic study, magnetic susceptibility, and ${\gamma}$-ray spectrometer, and identify petrographic characteristics. Also we will select candidate areas of fresh rock to change the stone used for three storied stone pagoda as from its provenance is presumed. According to the results of visual inspection, the stones used for the three storied stone pagoda are similar to the features of Namsan granite, which is distributed around Gyeongju-si, and when it comes to the section of the stupa finial, the features of all the parts from the stupa finial is similar to Namsan granite except for the section of Jeweled cover. On the other hand, the color, the composition, and the mineral size of the stones in the section from the part of jeweled cover are similar to Tohamsan granite. As a result of none-destruction inspection, it seems that the stones used for the three stories stone pagoda except for the section of jeweled cover are similar to the values for the magnetic susceptibility and the ${\gamma}$-ray spectrometer. On the other hand, Jeweled cover and the values of Tohamsan granite are alike. Namsan granite is appropriate in case that the stone used for three storied stone pagoda must be replaced to fresh rock because of damage by weathering. Meanwhile, Namsan granite is seperated from Yangsan fault. Due to this fact, Namsan granite appears to not only Mt. Namsan in Gyeongju, but also Dongcheon-dong, Gyeongju, and Huenggok-ri, Pohang. As a result, these two areas are suitable to the candidate area to change the stone used for three storied stone pagoda.

• Journal of the Korean Mathematical Society
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• v.44 no.6
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• pp.1339-1350
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• 2007

Here we consider bihyperelliptic curves, i.e., double covers of hyperelliptic curves. By applying the theory of quadruple covers, among other things we prove that the bihyperelliptic locus in the moduli space of smooth curves is irreducible and unirational $g{\geq}4{\gamma}+2{\geq}10$.

• Journal of Radiation Protection and Research
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• v.39 no.1
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• pp.21-29
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• 2014

A new cold neutron triple-axis spectrometer (Cold-TAS) was recently constructed at the 30 MWth research reactor, HANARO. The spectrometer, which is composed of neutron optical components and radiation shield, required a redesign of the segmented monochromator shield due to the lack of adequate support of its weight. To shed some weight, lowering the height of the segmented shield was suggested while adding more radiation shield to the top cover of the monochromator chamber. To investigate the radiological effect of such change, we performed MCNPX simulations of a few different configurations of the Cold-TAS monochromator shield and obtained neutron and photon intensities at 5 reference points just outside the shield. Reducing the 35% of the height of the segmented shield and locating lead 10 cm from the bottom of the top cover made of polyethylene was shown to perform just as well as the original configuration as radiation shield excepting gamma flux at two points. Using gamma map by MCNPX, it was checked that is distribution of gamma. Increased flux had direction to the top and it had longer distance from top of segmented shield. However, because of reducing the 35% of the height, height of dissipated gamma was lower than original geometry. Reducing the 35% of the height of the segmented shield and locating lead 10cm from the bottom of the top cover was selected. After changing geometry, radiation dose was measured by TLD for confirming tester's safety at any condition. Neutron(0.21 ${\mu}Svhr^{-1}$) and gamma(3.69 ${\mu}Svhr^{-1}$) radiation dose were satisfied standard(6.25 ${\mu}Svhr^{-1}$).

• Journal of Korean Society of Rural Planning
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• v.30 no.1
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• pp.57-66
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• 2024

This study aimed to develop a precise vegetation cover classification model for small streams using the combination of drone remote sensing and support vector machine (SVM) techniques. The chosen study area was the Idong stream, nestled within Geosan-gun, Chunbuk, South Korea. The initial stage involved image acquisition through a fixed-wing drone named ebee. This drone carried two sensors: the S.O.D.A visible camera for capturing detailed visuals and the Sequoia+ multispectral sensor for gathering rich spectral data. The survey meticulously captured the stream's features on August 18, 2023. Leveraging the multispectral images, a range of vegetation indices were calculated. These included the widely used normalized difference vegetation index (NDVI), the soil-adjusted vegetation index (SAVI) that factors in soil background, and the normalized difference water index (NDWI) for identifying water bodies. The third stage saw the development of an SVM model based on the calculated vegetation indices. The RBF kernel was chosen as the SVM algorithm, and optimal values for the cost (C) and gamma hyperparameters were determined. The results are as follows: (a) High-Resolution Imaging: The drone-based image acquisition delivered results, providing high-resolution images (1 cm/pixel) of the Idong stream. These detailed visuals effectively captured the stream's morphology, including its width, variations in the streambed, and the intricate vegetation cover patterns adorning the stream banks and bed. (b) Vegetation Insights through Indices: The calculated vegetation indices revealed distinct spatial patterns in vegetation cover and moisture content. NDVI emerged as the strongest indicator of vegetation cover, while SAVI and NDWI provided insights into moisture variations. (c) Accurate Classification with SVM: The SVM model, fueled by the combination of NDVI, SAVI, and NDWI, achieved an outstanding accuracy of 0.903, which was calculated based on the confusion matrix. This performance translated to precise classification of vegetation, soil, and water within the stream area. The study's findings demonstrate the effectiveness of drone remote sensing and SVM techniques in developing accurate vegetation cover classification models for small streams. These models hold immense potential for various applications, including stream monitoring, informed management practices, and effective stream restoration efforts. By incorporating images and additional details about the specific drone and sensors technology, we can gain a deeper understanding of small streams and develop effective strategies for stream protection and management.

• Journal of Korea Water Resources Association
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• v.52 no.9
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• pp.603-613
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• 2019

This study proposes a method to generate runoff ensemble members using a rainfall-runoff model based on the shot noise process (hereafter the rainfall-runoff model). The proposed method was applied to generate runoff ensemble members for three drainage basins of Daerim 2, Guro 1 and the Jungdong, whose results were then compared with the observed. The parameters of the rainfall-runoff model were estimated using the empirical formulas like the Kerby, Kraven II and Russel, also the concept of modified rational formula. Gamma and exponential distributions were used to generate random numbers of the parameters of the rainfall-runoff model. Especially, the gamma distribution is found to be useful to generate various random numbers depending on the pre-assigned relationship between mean and standard deviation. Comparison between the generated runoff ensemble members and the observed shows that those runoff ensemble members generated using the gamma distribution with its standard deviation twice of the mean properly cover the observed runoff.