• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.621-631
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• 2018

In this paper, an exact analytical solution is developed for the analysis of the post-buckling non-linear response of simply supported deformable symmetric composite beams. For this, a new theory of higher order shear deformation is used for the analysis of composite beams in post-buckling. Unlike any other shear deformation beam theories, the number of functions unknown in the present theory is only two as the Euler-Bernoulli beam theory, while three unknowns are needed in the case of the other beam theories. The theory presents a parabolic distribution of transverse shear stresses, which satisfies the nullity conditions on both sides of the beam without a shear correction factor. The shear effect has a significant contribution to buckling and post-buckling behaviour. The results of this analysis show that classical and first-order theories underestimate the amplitude of the buckling whereas all the theories considered in this study give results very close to the static response of post-buckling. The numerical results obtained with the novel theory are not only much more accurate than those obtained using the Euler-Bernoulli theory but are almost comparable to those obtained using higher order theories, Accuracy and effectiveness of the current theory.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.7
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• pp.1019-1023
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• 2001

An on-farm trial was conducted in temperature-controlled lactation rooms at a commercial pig farm to investigate the efficacy of broadcasting sow suckling grunts from day 4 of lactation, on increasing piglet growth to weaning. In the Broadcast treatment, sows and litters were exposed to a 3-min broadcast from loud-speakers every 42 min. The Control treatment was not exposed to the broadcast. All sows and litters had similar husbandry and piglets were provided with creep feed on the floor twice daily. In each of the three replicates in time, the Broadcast and Control treatments were allocated to different lactation rooms at random and there were 12 sows and litters per treatment per replicate. A total of four identical lactation rooms were available for the trial, each containing 28 conventional sow and litter crates with piglet heater in the creep area. A non-trial room separated the two treatment rooms in each replicate to minimise the chance that the broadcast grunt stimulation was audible to the Control treatment litters. Five "normal and average-looking" piglets from the trial litters were weighed twice, 7 d apart. The cohort of five piglets was identified by ear-tags and formed the experimental unit for the statistical analysis. The average (${\pm}SD$) age of piglets at initial weighing was 7.7(${\pm}2.22$) days. For each litter, mean piglet live weight at day 14 of lactation was estimated by linear regression of the two weights recorded seven days apart, when on average, the Broadcast treatment had been exposed to the stimulation for 10 days. Piglets in the Broadcast treatment were heavier (p<0.01) at day 14 of lactation compared to Control treatment (4.24 and 3.92 kg, respectively) and tended to have a greater average daily weight gain over the 7-d period (245 and 228 g/day, respectively; p<0.08). The results suggest piglet growth was improved by about 8% in response to the regular, timed broadcast of sow suckling grunts in the lactation shed. The independent contributions of milk and creep feed to the improved growth remain to be determined.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.37-52
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• 2017

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

• KDI Journal of Economic Policy
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• v.28 no.2
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• pp.179-198
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• 2006

This paper estimates relationships between the supply of national highways, measured in lane-km, and the quantity of traffic, measured in vehicle-km traveled. The analysis uses a panel data set of annual observations for the years 1984 to 2003. By using a log-linear lag effect model designed to capture short and long term effects, the paper estimates that national highway vehicle-km traveled has a lane-km elasticity of 0.268 at the country level (Non-Seoul Metropolitan area) and 0.41 at the Seoul metropolitan area for the short term. For the long term, the paper estimates 0.8 for the country level and 1.23 for the Seoul metropolitan area. This paper finds conclusive evidence that increases in highway lane-miles have generated traffic over the period of study, however the increasing ratio of the generated traffic decreases gradually, particularly during the late 1980s.

• Environmental and Resource Economics Review
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• v.24 no.2
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• pp.365-410
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• 2015

Block-rate structures are widely used in utility-pricing, including the Korean residential electricity sector. In the case of the current pricing structure, Korean citizens are highly concerned about incurring excessive electricity costs. For these reasons, there have been many discussions concerning mitigation of the strict pricing structure. Existing studies on the residential electricity demand function under block-rate structure have the following three issues - the consumer's budget constraint is non-linear, perceived price under block-rate structure is uncertain, block-rate structure has endogeneity in the price variable. In this context, this paper estimates the residential electricity demand function using micro-level household expenditure data and simulates the impact of alternative block-pricing schedules.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.2 s.314
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• pp.82-92
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• 2007

This paper describes a novel global shape (GS) feature based on radial basis function network (RBFN) and the extraction method of the proposed feature for 3D face recognition. RBFN is the weighted sum of RBfs, it well present the non-linearity of a facial shape using the linear combination of RBFs. It is the proposed facial feature that the weights of RBFN learned by the horizontal profiles of a face. RBFN based feature expresses the locality of the facial shape even if it is GS feature, and it reduces the feature complexity like existing global methods. And it also get the smoothing effect of the facial shape. Through the experiments, we get 94.7% using the proposed feature and hidden markov model (HMM) to match the features for 100 gallery set with those for 300 test set.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.205-216
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• 2009

As a subsequent study, this paper presents a comparative evaluation of structural responses in asphalt pavements with stabilized foundations. The approach based on a finite element analysis which incorporates non-linear behaviors of pavement geomaterials is used to estimate each performance indicator under standard single axle loading condition. In addition, results from laboratory tests are used to provide physical and mechanical properties of stabilized geomaterials for analyzing various pavement structures. Changes in pavement responses with varying layer thickness and stabilizer contents were investigated. It is found that the effect of layer thickness and stabilizer content is a critical factor in structural response of stabilized pavements. Moreover, a design criterion is proposed for selecting minimum contents of stabilizer of coarse-grained geomaterials based on a result of unconfined compressive strength and proper layer thickness of foundations.

• Tribology and Lubricants
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• v.36 no.1
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• pp.39-46
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• 2020

Air stages are usually applied to precision engineering in sectors such as the semiconductor industry owing to their excellent performance and extremely low friction. Since the productivity of a semiconductor depends on the acceleration and deceleration performance of the air stage, many attempts have been made to improve the speed of the stage. Even during sudden start or stop sequences, the stage should maintain an air film to avoid direct contact between pad and the rail. The purpose of this study is to quantitatively predict the dynamic behavior of the air stage when acceleration and deceleration occur. The air stage is composed of two parts; the stage and the guide-way. The stage transports objects to the guideway, which is supported by an externally pressurized gas bearing. In this study, we use COMSOL Multiphysics to calculate the pressure of the air film between the stage and the guide-way and solve the two-degree-of-freedom equations of motion of the stage. Based on the specified velocity conditions such as the acceleration time and the maximum velocity of stage, we calculate the eccentricity and tilting angle of the stage. The result shows that the stiffness and damping of the gas bearing have non-linear characteristics. Hence, we should consider the operating conditions in the design process of an air stage system because the dynamic behavior of the stage becomes unstable depending on the maximum velocity and the acceleration time.

• International Journal of Korean Welding Society
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• v.5 no.1
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• pp.15-28
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• 2005

The ball shear test was investigated in terms of the effects of test parameters, i.e., shear height and shear speed, with an experimental and non-linear finite element analysis for evaluating the solder joint integrity of area array packages. Two representative Pb-free solder compositions were examined in this work: Sn-3.5Ag-0.75Cu and In-48Sn. The substrate was a common SMD type with solder bond pad openings of 460 $\mu$m in diameter. The microstructural investigations were carried out using SEM, and the IMCs were identified with EDS. Shear tests were conducted with the two varying test parameters. It could be observed that increasing shear height, at fixed shear speed, has the effect of decreasing shear force for both Sn-3.5Ag-0.75Cu and In-48Sn solder joints, while the shear force increased with increasing shear speed at fixed shear height. Too high shear height could cause some undesirable effects on the test results such as unexpected high standard deviation values or shear tip sliding from the solder ball. The low shear height conditions were favorable for screening the type of brittle interfacial fractures or the degraded layers in the interfaces. The shear speed conditions were discussed with the stress analyses of the solder ball, and we cannot find any conspicuous finding which is related to optimum shear speed from the stress analyses.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1133-1133
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• 2001

Fruit sweetness, as indexed by total soluble solids (TSS), and fruit acidity are key factors in the description of the fruit eating quality. Our group has been using short wave NIR spectroscopy (SW-NIR; 700-1100 nm) in combination with chemometric methods (PLS and MLR) for the non-invasive determination of the fruit eating quality (1,2). In order to further improve calibration performance, we have investigated SW-NIR spectra of sucrose and D-glucose. In previous reports on the band assignment for these sugars in the 1100-2500 nm spectral region (3-7), it has been established that change in concentration, temperature and physical state of sugars reflects on the shape and position of the spectral bands in the whole NIR region(5-7). The effect of change in concentration and temperature of individual sugar solutions and sugar spiked Juice samples was analysed using combined spectroscopic (derivative, difference, 2D spectroscopy) and linear regression chemometric (PLS, MLR) techniques. The results have been compared with the spectral data of a range of fruit types, varying in TSS content and temperature. In the 800-950 nm spectral region, the B-coefficients for apples, peaches and nectarines resemble those generated in a calibration of pure sucrose in water (Fig. 1). As expected, these fruits exhibit better calibration and prediction results than those in which the B-coefficients were poorly related to those for sugar.(Figure omitted).