• Geophysics and Geophysical Exploration
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• v.23 no.4
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• pp.230-242
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• 2020

We performed a magnetotelluric (MT) survey to delineate the geological structures below the depth of 20 km in the Gyeongju area where an earthquake with a magnitude of 5.8 occurred in September 2016. The measured MT data were severely distorted by electrical noise caused by subways, power lines, factories, houses, and farmlands, and by vehicle noise from passing trains and large trucks. Using machine-learning methods, we classified the MT time series data obtained near the railway and highway into two groups according to the inclusion of traffic noise. We applied three schemes, stochastic gradient descent, support vector machine, and random forest, to the time series data for the highspeed train noise. We formulated three datasets, Hx, Hy, and Hx & Hy, for the time series data of the large truck noise and applied the random forest method to each dataset. To evaluate the effect of removing the traffic noise, we compared the time series data, amplitude spectra, and apparent resistivity curves before and after removing the traffic noise from the time series data. We also examined the frequency range affected by traffic noise and whether artifact noise occurred during the traffic noise removal process as a result of the residual difference.

• Animal Bioscience
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• v.34 no.4
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• pp.701-713
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• 2021

Objective: The present work was undertaken to evaluate the effects of storage time, choline chloride, and high concentrations of Cu and Zn on the kinetic behavior of vitamin degradation during storage in two vitamin premixes and four vitamin-trace mineral (VTM) premixes. Methods: Two vitamin premixes (with or without 160,000 mg/kg of choline) were stored at 25℃ and 60% humidity. Besides, four VTM premixes were used to evaluate the effects of choline (0 vs 40,000 mg/kg) and trace minerals (low CuSO4+ZnO vs high CuSO4+ZnO) on vitamin stability in VTM premixes stored in room, and the VTM premixes were stored in room temperature at 22℃. Subsamples from each vitamin and VTM premix were collected at 0, 1, 2, 3, 6, and 12 months. The retention of vitamin A (VA), vitamin D3 (VD3), vitamin E (VE), vitamin K3 (VK3), vitamin B1 (VB1), vitamin B2 (VB2), vitamin B3 (VB3), vitamin B5 (VB5), and vitamin B6 (VB6) in vitamin premixes and VTM premixes during storage was determined. The stability of vitamins in vitamin premixes and VTM premixes was determined and reported as the residual vitamin activity (% of initial) at each sampling point. Results: The effect of choline on VK3 retention was significant in vitamin premixes (p<0.05). The negative effect of storage time was significant for the retentions of VD3, VK3, VB1, VB2, VB5, and VB6 in vitamin premix (p<0.05). For VTM premixes, negative effect of storage time was significant (p<0.05) for the losses of vitamin in VTM premixes. Choline and high concentrations of Cu and Zn significantly increased VA, VK3, VB1, and VB2 loss during storage (p<0.05). The supplementation of high concentrations of Cu and Zn significantly decreased the concentrations of VD3 and VB6 (p<0.05) in VTM premixes at extended storage time. Conclusion: The maximum vitamin stability was detected in vitamin and VTM premixes containing no choline or excess Cu and Zn. The results indicated that extended storage time increased degradation of vitamin in vitamin or VTM premixes. These results may provide useful information for vitamin and VTM premixes to improve the knowledge of vitamin in terms of its stability.

• Korean Journal of Poultry Science
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• v.15 no.3
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• pp.211-218
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• 1988

Data on egg number from time of first lay to 71 week of age were obtained from samples of single comb white leghorn breeder and brown layer breeder populations which were raised at manny breeding Co. These data were used to estimate the heritabilities of age at sexual maturity, early egg number, residual egg number and annual egg number. Also, the genetic correlation coefficients between these traits were estimated and selection efficiencies of each segment in early part record were estimated by use of the heritabilities and generic correlations. The estimated heritabilities and standard errors in two lines(W and B) were $0.30\pm0.07$ and $0.33\pm0.08$ at early records, $0.19\pm0.06$ and $0.18\pm$0.05 at residual records and $0.37\pm0.09$ and $0.49\pm0.10$ at time of first lay. Those at annual records were $0.24\pm0.06$ equally. The estimated correlation coefficients and standard errors between early record and annual record were $0.76\pm0.08$ and $0.77\pm0.07$. Those between early record and residual record were $0.46\pm0.15$ and $0.39\pm0.16$ respectively. At improving annual egg production per year, selection based on early part record(SM to 40 week of age) would be 69% more efficient than on annual record in line W and 80% more efficient than on annual record in line B. But, if it were considered that egg weight decreased due to sexual maturity and cost for data collection, use of selected segment from 35~40week of age in line W and from 31~40 week of age in line B would be desired in spite of a. small loss in relative selection efficiency. The generation interval would not be shortened.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.401-404
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• 2007

Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint face, and energy required for welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy, amount of upset, working time, and residual stresses in the joint. Inertia welding was conducted to make the large rotor shaft for low speed marine diesel engine, alloy steel for shaft of 140mm. Due to different material characteristics, such as, thermal conductivity and flow stress, on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.191-194
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• 2007

In hot embossing lithography which has shown to be a good method to fabricate polymeric patterns for IT and bio components, it is very important to determine the proper process conditions of pressure, temperature, and time. It is also a key factor for predicting the optical properties of final product to calculate residual stress distribution after the embossing process. Therefore, to design the optimum process with right conditions, the ability to predict viscoelastic behavior of polymer during and after the hot embossing process is required. The objective of the present investigation is to establish simulation technique based on constitutive modeling of polymer with experiments. To analyze deformation behavior of viscoelastic polymer, the large strain material properties were obtained from quasi-static compression tests at different strain rates and temperatures and also stress relaxation tests were executed. With this viscoelastic material model, finite element simulation of hot embossing was executed and stress distribution is obtained. Proper process pressure is very important to predict the defect and incomplete filling.

• Fibers and Polymers
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• v.4 no.2
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• pp.89-96
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• 2003

A vertebral cage is a hollow medical device which is used in spine forgery. By implanting the cage into the spine column, it is possible to restore disc and relieve pressure on the nerve roots. Most cages have been made of titanium alloys but they detract the biocompatibility. Currently PEEK (polyether ether ketone) if applied to various implants because it has good properties like heat resistance, chemical resistance, strength, and especially biocompatibility. A new shape of vertebral cage is designed and injection molding of PEEK is considered for production. Before injection molding of the cage, it is needed to evaluate process conditions and properties of the final product. Variables affecting the shrinkage of the cage are considered, e.g., injection time, packing pressure, mold temperature, and melt temperature. By using the numerical simula-tion program, MOLDFLOW, several cases are studied. Data files obtained by MOLDFLOW analysis are used for stress anal-ysis with ABAQUS, and shrinkage and residual stress fields are predicted. With these results, optimum process conditions are determined.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1762-1764
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• 1999

We investigated the annealing effect on generating pretilt angle and aligning liquid crystal (LC) using the photo-depolymerization reaction in this study. In case of rubbing polyimide (PI) surface with the side chain, pretilt angle tends to increase with increasing the annealing time. It is considered because the steric interaction is increased by annealing which cause the side chain to come back to original position. For obliquely irradiating ultraviolet (UV) light on PI surface, pretilt angle shows to $0^{\circ}$ and is increased by annealing. The pretilt angle in rubbed PI surface is much higher than in photo-aligned PI surface. It is attributed to the steric interaction and the number of LC molecular arrangement on azimuthal direction. In addition. in case of obliquely irradiating UV light on PI surface. it showed LC alignment to increase by annealing. It can be regarded due to the fact that the re-alignment of LC molecule is improved to residual polymer direction by annealing.

• Journal of Positioning, Navigation, and Timing
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• v.2 no.1
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• pp.59-65
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• 2013

The signal broadcast from a GPS satellite experiences code delay and carrier phase advance while passing through the ionosphere, which causes a signal error. Many ionosphere models have been studied to correct this ionospheric delay error. In this paper, the ionosphere modeling for the Korean Peninsula was carried out using a spherical harmonics based model. In contrast to the previous studies, we considered a real-time ionospheric delay correction model using fewer number of basis functions. The modeling performance was evaluated by comparing with a grid model. Total number of basis functions was set to be identical to the number of grid points in the grid model. The performance test was conducted using the GPS measurements collected from 5 reference stations during 24 hours. In the test result, the modeling residual error was smaller than that of the existing grid model. However, when the number of measurements was small and the measurements were not evenly distributed, the overall trend was found to be problematic. For improving this problem, we implemented the modeling with additional virtual measurements.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.752-757
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• 1999

Studies were made of digestion of timothy (Pheleum pretense) hay, tall fescue (Festuca elatior) hay, and rice (Oryza sativa) straw in pure cultures of rumen anaerobic fungus, Neocallimastix frontails MCH3. The fungus was inoculated on ground forages (1%, w/v) in an anaerobic medium and incubated at $39^{\circ}C$. Incubation was continued for 24, 48, 72 and 96 h. The losses of dry matter, xylose and glucose of forage during incubation were determined at the end of these incubation periods. Xylose and glucose were considered to be released from xylan and cellulose, respectively. The digested xylan to digested cellulose (X/C) ratios of the substrate were calculated. Xylanase and carboxymethyl cellulose (CMCase) of culture supernatant and residual substrate was measured at the same time. The X/C ratios in the cultures on timothy hay and rice straw were greater than 0.5 in the first 24-h incubation period. The values were smaller than 0.3 in tall fesque. The ratio of xylanase activity to that of CMCase in the first 24-h incubation period correlated well with the traits in X/C ratio. However xylanase activity was still superior to CMCase in the following incubation period (48 to 96 h), although the glucose (designated as cellulose) was more intensively digested than xylose (designated as xylan). The production of these polysaccharidases appeared to correlate with substrate cell-wall sugar composition, xylose to glucose ratios, at the beginning of fast growing period.

• Steel and Composite Structures
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• v.15 no.3
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• pp.343-355
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• 2013

Shear failure and core concrete crushing at plastic hinge region are the two main failure modes of bridge piers, which can make repair impossible and cause the collapse of bridge. To avoid the two types of failure of pier, a composite pier was proposed, which was formed by embedding high strength concrete filled steel tubular (CFT) column in reinforced concrete (RC) pier. Through cyclic loading tests, the seismic performances of the composite pier were studied. The experimental results show that the CFT column embedded in composite pier can increase the flexural strength, displacement ductility and energy dissipation capacity, and decrease the residual displacement after undergoing large deformation. The analytical analysis is performed to simulate the hysteretic behavior of the composite pier subjected to cyclic loading, and the numerical results agree well with the experimental results. Using the analytical model and time-history analysis method, seismic responses of a continuous girder bridge using composite piers is investigated, and the results show that the bridge using composite piers can resist much stronger earthquake than the bridge using RC piers.