Learning-to-export Effect as a Response to Export Opportunities: Micro-evidence from Korean Manufacturing

This paper aims to investigate whether there is empirical evidence supporting the learning-to-export hypothesis, which has received little attention in the literature. By taking full advantage of plant-product level data from Korea during 1990-1998, we find some evidence for the learning-to-export effect, especially for the innovated product varieties with delayed exporters: their productivity, together with research and development and investment activity, was superior to their matched sample. On the other hand, this learning-to-export effect was not significantly pronounced for industries protected by import tariffs. Thus, our empirical findings suggest that it would be desirable to implement certain policy tools to promote the learning-to-export effect, whereas tariff protection is not justifiable for that purpose

Deformation and fracture of silicon electrodes in lithium-ion batteries

We have performed a number of experiments to examine the mechanical behavior of amorphous silicon -electrodes of lithium-ion batteries. In particular, we have measured the fracture energy of lithiated silicon thin-film electrodes as a function of lithium concentration. The fracture energy is found to be similar to that of pure silicon and essentially independent of the concentration of lithium. Thus, although lithiated silicon can flow plastically, it appears to fracture in a brittle manner. We have also varied the rate of lithiation of amorphous silicon thin films while -simultaneously measuring stresses. Increasing the rate of lithiation resulted in a corresponding increase in the flow stress. These observations indicate that rate-sensitive plasticity occurs in a-Li × Si electrodes at room temperature and at charging rates typically used in lithium-ion batteries. Using a simple mechanical model, we have extracted material parameters from our experiments, finding a good fit to a power law relationship between the plastic strain rate and the stress. The observations of rate-sensitivity provide insight into the unusual ability of a-Li × Si to flow plastically while fracturing in a brittle manner. Moreover, the results have direct ramifications concerning the rate capabilities of silicon electrodes: faster charging rates (i.e., strain rates) result in larger stresses and hence larger driving forces for fracture

Graphene-enhanced raman spectroscopy reveals the controlled photoreduction of nitroaromatic compound on oxidized graphene surface

Although graphene-enhanced Raman spectroscopy has been investigated for several years, there have been no studies that have applied it to real-time observations of chemical catalytic reactions. Here, we report that UV/ozone-treated oxidized graphene was used to both control and monitor the photoreduction of an adsorbed nitroaromatic dye compound. Graphene-enhanced Raman spectroscopy studies show that more oxidized graphene surface leads to faster photoreduction. This is due to the lowering of the Fermi level in the oxidized graphene, which is in agreement with the highest occupied molecular orbital level of the adsorbed dye molecule, leading to a rapid electron transfer from graphene to the dye. Our findings will be useful in understanding and exploiting the photocatalytic properties of oxidized graphene on adsorbed molecular species.

Do Financial Analysts Facilitate Investors’ Assessment Of Earnings?: Evidence From The Korean Stock Market

This paper seeks to enhance our understanding of financial analysts in assisting market investors’ use of accounting earnings in the Korean stock market. We examine whether stock returns differentially reflect earnings information for firms with analyst coverage. We propose that the role of analysts as external monitors as well as information intermediaries enhances the market investors’ valuation of earnings. We find that market valuation of earnings is higher for firms with analyst following. Furthermore, market investors’ valuation of earnings increases (or decreases) with the number of analysts (or with the dispersion of analysts’ forecasts). This suggests that the beneficial effect of analysts arises through the quantity and quality of analysts’ information. This study contributes to the literature by investigating the important role of analysts in emerging market

β-Catenin binds to the downstream region and regulates the expression C-reactive protein gene

C-Reactive protein (CRP) is a major acute-phase response protein, which is activated by various cytokines. We investigated the mechanism of TNF-α-induced CRP expression and found that the p50 subunit of NF-κB was responsible for the transcriptional activation of CRP. Since the p50 protein acts as a positive regulator of CRP expression without an inherent transactivation domain, we looked for an interaction partner that could provide p50 with such a domain. We found that β-catenin enhanced the expression of a CRP mRNA in concert with p50 subunit. Protein–protein interaction between p50 and β-catenin was important for CRP expression and their interactions to CRP promoter were induced after TNF-a treatment. Since gene expression depends upon the proximity of promoters and distal regulatory sites, we explored the long-range genomic interaction at the CRP locus by chromosome conformation capture (3C). We identified a binding site for β-catenin in the downstream of CRP gene by 3C and confirmed TNF-α-induced association of β-catenin and p50 by chromatin immunoprecipitation and co-immunoprecipitation assays. Our findings provide evidence that transcription of the CRP gene depends upon p50 and β-catenin proteins, which is accompanied by close proximity between promoter and the downstream region of CRP gene

Time Delay Estimation Using LASSO (Least Absolute Selection and Shrinkage Operator)

In decades, many researchers have studied the time delay estimation (TDE) method for the signals in the two different receivers. The channel estimation based TDE is one of the typical TDE methods. The channel estimation based TDE models the time delay between two receiving signals as an impulse response in a channel between two receivers. In general the impulse response becomes sparse. However, most conventional TDE algorithms cannot have utilized the sparsity. In this paper, we propose a TDE method taking the sparsity into consideration. The performance comparison shows that the proposed algorithm improves the estimation accuracy by 10 dB in the white gaussian source. In addition, even in the colored source, the proposed algorithm doesn't show the estimation threshold effect

Natural durability of some hardwoods imported into korea for deck boards against decay fungi and subterranean termite in accelerated laboratory tests

This study evaluated the natural durability of seven imported hardwoods (bangkirai, burckella, ipe, jarrah, kempas, malas, and merbau) used for deck boards against decay fungi (Fomitopsis palustris, Gloeophyllum trabeum, Trametes versicolor, and Irpex lacteus) and the subterranean termite (Reticulitermes speratus kyushuensis) in accelerated laboratory tests. Ipe, jarrah, and merbau were very durable to fungal attack, with performance comparable to ACQ-treated wood. Bangkirai, burckella, kempas, and malas were classified as durable or moderately durable, depending on the fungal species tested. All wood species except for merbau were highly resistant to termite attack. Termite resistance was similar to ACQ-treated wood. Merbau showed somewhat less than all other species but still significant termite resistance. These results indicated that selected naturally durable hardwood species could inhibit fungal and termite attacks as effectively as ACQ treatment. The natural durability of wood species tested in this study is most likely due to the biocidal extractive content of the wood

Scanning AC Nanocalorimetry Study of Zr/B Reactive Multilayers

The reaction of Zr/B multilayers with a 50 nm modulation period has been studied using scanning AC nanocalorimetry at a heating rate of approximately $10^3 K/s$. We describe a data reduction algorithm to determine the rate of heat released from the multilayer. Two different exothermic peaks are identified in the nanocalorimetry signal: a shallow peak at low temperature (200–650°C) and a sharp peak at elevated temperature (650–800°C). TEM observation shows that the first peak corresponds to heterogeneous inter-diffusion and amorphization of Zr and B while the second peak is due to the crystallization of the amorphous Zr/B alloy to form $ZrB_2$.Engineering and Applied Science