• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.369-374
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• 2007

For a stability design of steel frames, AISC-LRFD specification recommend to use Alignment Chart and story-based methods in order to determine an effective budding length. Recently, elastic buckling analysis, which is the method that calculate the effective length of members using eigenvalue of the overall structure, has been widely used in practical design of steel frames because this method can be performed effectively and automatically by computers. However, it can in some cases lead to unexpectedly large effective length in column having small axial forces. Therefore, this paper propose a method using elastic buckling analysis, which estimate a proper effective buckling length for all members having a small axial force. For verification of proposed method, it is compared with system based approach and stiffness distribution factor method. As a result, proposed method can rationally solve a problem in some case of column having small axial force. Also, adoption range for proposed method is established.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.135-137
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• 2004

In this study we'll deal with the small-sized metalized film capacitors with large capacity which head have $5mm{\times}5mm{\times}2.5mm$ dimension. The lead wire is used to weld at both sides of capacitors. At that time the position gap between the welding machine and lead wire supplier would cause the welding error. Also, during the tapping processing of metalized film capacitors, the interval error among the capacitors, the length error of lead frame attached at the capacitors, and the straightness distortion of the lead frame could happen. As mentioned, four kinds of error parameters will be measured and analyzed by using the automatic visual inspection system that is implemented with CCD camera, optical parts, background lighting, and image processing algorithms. Finally we are able to achieve success rate above 99% to detect the welding faults of capacitors in the field test.

• Journal of Welding and Joining
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• v.16 no.4
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• pp.109-116
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• 1998

The three-dimensional profile of a solder fillet is predicted by minimizing the surface tension and gravity energies of the solder joint using finite element modeling. Geometric complexity stemming from the inclined plane of the gullwing lead is resolved by employing three element types. These element types are used to describe the joint profile formed on the vertical, inclined and interfacial planes. The predicted solder joint profiles show good agreements with the experimental data provided that the solder volume is adjusted considering the wicking effects. Effects of the pad length, inclined lead angle and solder volume on joint profiles are also investigated.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.06a
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• pp.129-134
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• 2003

In this paper, we determine optimal reduction in the lead time and setup cost for some stochastic inventory models. And we propose more general model that allow the backorder rate as a control variable. We first assume that the lead time demand follows a normal distribution. And we assume that the backorder rate is dependent on the length of lead time through the amount of shortages. The stochastic models analyzed in this paper are the classical continuous and periodic review policy models with a mixture of backorders and lost sales. For each of these models, we provide a sufficient conditions for the uniqueness of the optimal operating policy. We also develop algorithms for solving these models and provide illustrative numerical examples.

• Progress in Superconductivity and Cryogenics
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• v.2 no.2
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• pp.6-10
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• 2000

1.5 kA class HTS current leads for a SMES magnet, which are connected to a conventional vapor cooled copper leads, were designed. The HTS leads are composed of Bi-2223/Ag-Au tapes and a stainless stell tube. The estimated critical current of the lead is about 1.6 kA at 77.3 K and in a self magnetic field, and the heat input to the liquid helium from the cold end of the 35 cm lead is 0.4 W/lead. It has been made clear that the heat input decreases with increase of the lead length and decrease of the warm end temperature and Ag-Au/SC ratio.

• Asian Journal of Atmospheric Environment
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• v.7 no.1
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• pp.56-63
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• 2013

Children are particularly vulnerable to adverse health effects associated with heavy metal exposure. The goal of this study was to investigate the relationship between proximity to an industry complex and blood lead and urinary cadmium levels for children aged 7-13 who lived in Ulsan where a big petrochemical complex is located. We conducted a questionnaire survey to collect data including sociodemographics, daily habits, residential environment, etc. We also analyzed blood lead and urinary cadmium levels using Atomic Absorption Spectrometry (AAS). Data were analyzed using regression analysis. All statistical analyses were conducted with SAS software version 9.2. We calculated distance by using a Geographic Information System (ArcGIS version 10.0). The geometric mean blood lead level was 1.55 ${\mu}g/dL$ (boys: 1.59 ${\mu}g/dL$, girls: 1.51 ${\mu}g/dL$), and the geometric mean urinary cadmium level was 0.51 ${\mu}g/g$ creatinine (boys: 0.45 ${\mu}g/g$ creatinine, girls: 0.58 ${\mu}g/g$ creatinine). In the results of regression analyses, we found that urinary cadmium levels significantly decreased as distance between residence and industrial complex increased after adjusting for age, gender, income, passive smoking and the length of residence. This result was opposite to that for lead levels. Our observations support the hypothesis that urinary cadmium levels in children are related to their proximity to an industrial complex.

• Journal of Environmental Science International
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• v.11 no.4
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• pp.319-325
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• 2002

This experiment was carried out to investigate the effects of heavy metals (copper, cadmium, lead and chrome) on the growth of plant and seed germination of Arabidopsis thaliana treated with various concentrations of heavy metals. Cadmium and chrome among the 4 heavy metals had no effect on the growth of stem even in the concentration fifty times higher than the official standard concentration of pollutant exhaust notified by the Ministry of Environment. The official standard concentration of cadmium, however, stimulated the growth of stem in general, increasing leaf size and surface area, although it had no effect on the length of stem. But the growth of stem was decreased about 18% in the official standard concentration of pollutant exhaust of lead and copper. There was no growth of root in the concentration of lead and copper ten times higher than the official standard concentration. Cadmium and chrome had no effect on the seed germination, but lead and copper decreased the rate of seed germination. Seeds were not germinated in the concentration of copper ten times higher than the official standard concentration and in the concentration of lead fifty times higher than the official standard concentration. From this research three peculiar results were obtained. Chrome in the soil did not have much effect on the plant growth and seed germination of Arabidopsis thaliana. Cadmium stimulated the stem growth in an optimum concentration. But lead and copper reduced the plant growth and seed germination even in a small concentration, especially copper had the worse effect.

• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1207-1216
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• 2018

Discharge or water level predictions at tidally affected river reaches are currently still a great challenge in hydrological practices. This research aims to predict water level of the tide dominated site, Jamsu bridge in the Han River downstream. Physics-based hydrodynamic approaches are sometimes not applicable for water level prediction in such a tidal river due to uncertainty sources like rainfall forecasting data. In this study, TensorFlow deep learning framework was used to build a deep neural network based LSTM model and its applications. The LSTM model was trained based on 3 data sets having 10-min temporal resolution: Paldang dam release, Jamsu bridge water level, predicted tidal level for 6 years (2011~2016) and then predict the water level time series given the six lead times: 1, 3, 6, 9, 12, 24 hours. The optimal hyper-parameters of LSTM model were set up as follows: 6 hidden layers number, 0.01 learning rate, 3000 iterations. In addition, we changed the key parameter of LSTM model, sequence length, ranging from 1 to 6 hours to test its affect to prediction results. The LSTM model with the 1 hr sequence length led to the best performing prediction results for the all cases. In particular, it resulted in very accurate prediction: RMSE (0.065 cm) and NSE (0.99) for the 1 hr lead time prediction case. However, as the lead time became longer, the RMSE increased from 0.08 m (1 hr lead time) to 0.28 m (24 hrs lead time) and the NSE decreased from 0.99 (1 hr lead time) to 0.74 (24 hrs lead time), respectively.

• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.62-65
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• 2014

To minimize most heat loss of current lead for high-temperature superconducting (HTS) rotating machine, the choice of conductor properties and lead geometry - such as length, cross section, and cooling surface area - are one of the various significant factors must be selected. Therefore, an optimal lead for large scale of HTS rotating machine has presented before. Not let up with these trends, this paper continues to improve of diminishing heat loss for HTS part according to different model. It also determines the simplification conditions for an evaluation of the main flux flow loss and eddy current loss transient characteristics during charging and discharging period.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1783-1790
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• 2023

Barium Bismuth Oxide Borate (BBOB) has been synthesized for the first time using solution combustion technique. SEM analysis reveal flower shape of the nanoparticles. The formation of the nanoparticles has been confirmed through XRD & FTIR studies which gives the physical and chemical structure of the novel material. The UV light absorption is observed in the range 200-300 nm. The present study highlights the radiation shielding ability of BBOB for different radiations like X/Gamma rays, Bremsstrauhlung and neutrons. The gamma shielding efficiency is comparable to that of lead in lower energy range and lesser than lead in the higher energy range. The bremsstrauhlung exposure constant is comparably larger for BBOB NPs than that of concrete and steel however it is lesser than that of lead. The beauty of BBOB nanoparticles lies in, high absorption of radiations and low emission of secondary radiations when compared to lead. In addition, the neutron shielding parameters like scattering length, absorption and scattering cross sections of BBOB are found to be much better than lead, steel and concrete. Thus, BBOB nanoparticles are highly efficient in absorbing X/Gamma rays, neutrons and bremsstrauhlung radiations.