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We perform an event study on 2824 cases of domestic mergers and acquisitions (M&A) that were disclosed in the Korean domestic stock exchange and took effect between 2002 and 2015. We focus on Korean capital markets to define the factor variables affecting the disclosure effect of M&A in high-tech industries and the effect of disclosure on long-term performance. We find the following. First, the disclosure effect of M&A benefits acquirers’ shareholder wealth; this effect is more pronounced for high-tech firms than for non-high-tech firms. Second, M&A of high- and non-high-tech firms harm acquirers’ shareholder wealth via the disclosure effect. Finally, M&A between high- and non-high-tech firms negatively affect long-term firm performance. However, acquirers that are mature high-tech firms have a positive effect on long-term performance. This result affirms that organizationally mature firms adapt better to highly specialized technologies and knowledge that are not yet internalized as corporate routines owing to their learned capabilities and breadth of experience. This study provides a significant novel perspective on high-tech M&A by emphasizing the financial performance of firms involved in them.

Microstructural evolution during injection casting Cu50Zr50−xTix (x = 0–8) alloys has been investigated using X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. Cubic CuZr(Ti) B2 phase is competing against the glass transition during solidification for all the alloys and the primary B2 phase has transformed into the martensitic phase for x

For future exascale computing systems, ultra-high-density memories would be required that consume low power to process massive data. Of the various memory devices, 3D-stacked DRAMs using TSVs are a perfect solution for this purposes. In addition to providing high capacity, these provide functional flexibility to the computing system by attaching a logic die in each 3D-stacked DRAM chip. However, the high capacity 3D-stacked DRAMs suffer from a significant loss of refresh power, which is solely required to maintain data. Although various schemes have been proposed to mitigate this issue, they cannot be adopted by commercial products due to compatibility issues. To tackle this issue, we propose EXTREME, which effectively reduces the refresh power of 3D-Stacked DRAMs. In order to retain the compatibility with OS, a simple page table manager is implemented at the logic die of 3D-stacked DRAM devices, which pins the page table to a specific memory space. The experiment results demonstrate that this reduces the refresh power at idle time by up to 98 percent with 16 KB of SRAM (static RAM) and 64 KB of DRAM register overhead for a 2 GB 3D-stacked DRAM device.

Molecular dynamics simulations were performed to investigate the effect of the enthalpy of mixing on the atomic level structure and plasticity of binary metallic glasses by using an ideal model potential. Whereas some model alloys with a strong positive enthalpy of mixing solidified into mixtures of microcrystalline domains of face-centered cubic or hexagonal close-packed crystal structures, the other alloys solidified into amorphous structures. Various structural properties of the amorphous alloys were analyzed as a function of the enthalpy of mixing interaction parameter. The deformation behavior of the amorphous samples was discussed in terms of atomic-level structural features such as the fraction of icosahedral clusters, the degree of short-range ordering and potential energies of atomic clusters in order to find a clue on the relationship between the mechanical properties and atomic structure of the amorphous alloys.

This study analyzes Korean firms’ motives for cross-border M&As, Asia’s representative emerging capital market, from the perspective of financial attributes, and defines the effects of group attributes of cross-border M&As on the wealth of acquiring firms’ shareholders. As for the group attributes of cross-border M&As, shareholders of small firms with high ROA do not like cross-border M&As, because the shareholders of small acquiring firms with sufficient internal growth factors are reluctant to transfer their present wealth to shareholders of foreign target firms. We also verify that the diversification effect with regard to cross-border M&As is accompanied by the diversification discount, but that firms with ample internal funds due to their high ROA like entering into new industries through cross-border M&As. Lastly, when target companies are listed in countries with highly uncertain GDP growth rates, acquiring firms’ value decreased.

The effect of the type of the crystalline phase and its volume fraction on the mechanical property of Cu50Zr50-xTix alloys (x = 0-10) bulk metallic glass composites has been investigated in this study. Up to 6 at% of Ti, B19’ phase particles distributed in the glassy matrix, while at 8 and 10% of Ti, B2 phase particles are retained in the glass matrix due to suppression of the eutectoid transformation of B2 phase and by avoidance of martensitic transformation of B2 into B19’. The volume fraction of crystalline phase is strongly dependent on the cooling rate. The larger volume fraction of the crystalline phases results in the lower yield stress, the higher plastic strain, and the more pronounced work hardening behavior. At the crystalline volume fraction below ~30%, the variation of the yield strength can be described by the rule of mixture model (ROM), while at the crystalline volume fraction higher than ~50% by the load-bearing model (LBM). At the crystal fractions between 30 and 50%, there is a yield strength drop and a transition from the ROM to the LBM. This transition is due to the formation of the crystalline structural framework at higher crystal fraction.

The deposition techniques of quantum dots (QDs) have great influence on the photovoltaic performances of quantum dot sensitised solar cells (QDSSCs). In this study, we report CdS/CdSe sensitised TiO2 solar cells focussing on the influence of two commonly used in situ QD deposition techniques (SILAR: successive ionic layer adsorption and reaction and CBD: chemical bath deposition). In addition to this, the QDSSC performance is enhanced due to better light harvesting capability of PbS quantum dots and makes large accumulation of photo-injected electrons in the conduction band of TiO2. When compared to power conversion efficiency (PCE) of 4.58% was obtained for PbS/CBD-CdS/CBD-CdSe cells when compared to PbS/SILAR-CdS/SILAR-CdSe. With chemical bath deposition, we achieved high surface coverage of QDs, which contributes to the increase in photocurrent,open circuit voltage and fill factor. Impedance spectroscopy revealed that the PbS/CBD-CdS/CBD-CdSe reduces recombination and increases charge collection efficiency and a long electron lifetime was achieved. To associate the assembling of QDs with the performance of QDSSCs a methodical characterization of morphology, optical and electro-chemical properties and its stability has been studied. We achieved PbS seeded CBD highlighting its robust consequences for the performance of QDSSCs.

In order to investigate the mechanical relaxation behaviors of a Zr28Y28Al22Co22 phase separating metallic glass, dynamic mechanical measurements of the tensile storage and loss moduli were performed for broad temperature and frequency ranges. The glass transition of each separated phase in the as-spun ribbon was manifested by the double decreasing of the storage modulus and two loss modulus peaks. The master curves for tanδ of the as-spun and heat-treated specimens were constructed according to the time-temperature superposition principle. From the temperature dependence of the shift factor, the activation energies for the primary and secondary relaxation of both specimens were calculated and the effects of the interconnected structure of the dual-phase as-spun ribbon and partially crystallized ribbon on the mechanical relaxation behaviors were studied.

Perfusion cultures of recombinant Chinese hamster ovary cells, producing recombinant antibody against the S surface antigen of Hepatitis B virus, were carried out in continuous and intermittent mode using a Centritech Lab II Centrifuge. In the continuous perfusion process, despite the absence of shear stress from the pump head, long-term operation was not possible because of continuously repeated exposure to oxygen limitation and low temperature, as well as shear stress from centrifugal force. In the intermittent perfusion processes, the frequency of cell-passage through the centrifuge was substantially reduced, compared with the continuous perfusion mode; however, the degree of reduction could not guarantee stable long-term operation. Although various operating parameters were applied in the intermittent perfusion cultures, high cell densities could not be maintained stably. In a single bioreactor culture system, a specific cell that is returned from the centrifuge to the bioreactor could be transferred from the bioreactor to the centrifuge again in the next cycle. These repetitive damages, caused by shear stress from the pump head and centrifugal force, as well as exposure to suboptimal conditions such as oxygen limitation and low temperature below 37 degrees C, were more serious at higher perfusion rates. Subsequently, damaged cells and dead cells were continuously accumulated in the bioreactor. Culture temperature shift from 37 to 33 degrees C increased antibody concentrations but showed inhibitory effects on cell growth. The negative effects of lowering culture temperature on cell growth overwhelmed the positive effects on antibody production. To protect cells from shear stress, Pluronic F-68 was 2-fold concentrated in the culture medium; nevertheless, a significantly higher concentration of Pluronic F-68 (2 g/L) may have inhibitory effects on cell growth.

To describe prominent premalar and cheek swelling as a previously undescribed clinical feature of thyroid-associated orbitopathy (TAO).Retrospective interventional case series.A retrospective case review of patients with prominent premalar and/or cheek swelling and TAO was undertaken. All patients who presented from March 2002 to February 2005 with complaints of premalar and/or cheek swelling in TAO were analyzed.Six female patients between the ages of 28 and 66 years (average, 44.2 years) who had complaints of prominent premalar and/or cheek swelling and TAO were included in the study, among 326 new patients with TAO (incidence: 1.84%). Five of the 6 patients had Graves hyperthyroidism. One initially had Hashimoto thyroiditis, which converted to Graves hyperthyroidism. In all cases, TAO preceded the thyroid disease or developed simultaneously (average time from TAO to thyroid disease was 3.0 months). No patient had received corticosteroids before premalar and/or cheek swelling. The premalar and/or cheek swelling was bilateral in all cases, but 2 of 6 were asymmetric. No diurnal fluctuation or tenderness in premalar and/or cheek swelling was noted. All improved incompletely over several months. Brow, eyelid swelling, and orbital-fat hypertrophy on radiologic examination was coincidentally noted in 5 of 6 cases. Pretibial myxedema was noted in one case. One case was associated with another autoimmune disease (rheumatoid arthritis).Prominent premalar and cheek swelling should be considered among the clinical features of TAO. The true incidence will become apparent as we question and examine patients more carefully regarding this entity and as we review premorbid photographs.

Estrogen-dependent transcriptional activation by estrogen receptor alpha (ERalpha) depends on the conformation of helices 3 and 12 in the ligand-binding domain. To better understand the function of helix 3 in ERalpha, we examined the role of charged residues, which are conserved in most steroid receptors in helix 3, in estrogen-dependent transactivation. The replacement of Asp-351 with lysine (D351K) or leucine (D351 L) completely abolished estrogen-dependent transactivation without affecting estrogen-binding, DNA-binding and homodimerization activities in ERalpha. The mutations dramatically reduced the ligand-dependent activation function 2 activity and impaired the ability of ERalpha to bind p160 coactivators. In addition, the D351K mutant effectively inhibited the transcriptional activation activity of wild-type ERalpha. Furthermore Asp-351 was required not only for the estrogen-dependent conformational change of wild-type ERalpha but also for the constitutive transcriptional activity and ligand-independent active conformation of ERalpha mutant Y537N. Similarly, in the orphan nuclear receptor called estrogen-related receptor 3 (ERR3), the replacement of Asp-273 (the corresponding amino acid to Asp-351 in ERalpha) with lysine abolished constitutive transcriptional activity of ERR3 without affecting DNA-binding activity and impaired the ability of the receptor to interact with p160 coactivators. These data suggest a role of Asp-351 in inducing and stabilizing the active conformation of ERalpha, and our results experimentally confirm the concept that Asp-351 in helix 3 interacts with the amide hydrogen of L540 in helix 12 to form a transcriptionally competent surface for binding p160 coactivators.

The Mokpo cable-stayed bridge has become a new landmark in Mokpo city, Korea. This bridge has a unique feature from an aesthetic and structural point of view and will be the second longest cable-st...

A design procedure for a structure's monitoring system using sensitivity analysis and a neural network is developed. The monitoring system is to be used to monitor damage to members critically affecting the overall safety of structures. Recently, many techniques for evaluating the damage of isolated members and models of simple structures have been investigated. However, actual structures are large, and their complex behavior may not be based on damage of isolated members or their simple models. To monitor large structures realistically, structures' data on behavior at many points need to be monitored. Identifying the optimal locations and numbers of these monitoring points and assessing the safety of the entire structure from the limited data are the monitoring system design problem. The procedure presented for this design problem is a two-step process. In the first step, using sensitivity analysis and damage-assessment techniques, individual members are ranked according to their influence on the failure probability of the entire structure or according to their effect on the abnormal behavior of the structure. Based on the rank, critical members are identified. In the second step, sensitivity analysis and a neural network are used to determine the optimal locations. In addition, the optimal number of sensors for monitoring damage to the critical members selected in step 1 is also suggested. Truss and frame examples are used to show the validity and applicability of the monitoring system design procedure.

Choristoma is a benign tumour defined as normal tissue in an ectopic location. Osseous choristoma, one subtype of this entity, occurring within the orbit has rarely been reported in the world literature. We report a 6-year-old girl with bilateral ocular osseous choristomas who presented with palpable nodules protruding from both upper lids. The radiological and clinical findings are described and previous reports are reviewed.

The imputation of missing values is necessary for the efficient use of DNA microarray data, because many clustering algorithms and some statistical analysis require a complete data set. A few imputation methods for DNA microarray data have been introduced, but the efficiency of the methods was low and the validity of imputed values in these methods had not been fully checked. We developed a new cluster-based imputation method called sequential K-nearest neighbor (SKNN) method. This imputes the missing values sequentially from the gene having least missing values, and uses the imputed values for the later imputation. Although it uses the imputed values, the efficiency of this new method is greatly improved in its accuracy and computational complexity over the conventional KNN-based method and other methods based on maximum likelihood estimation. The performance of SKNN was in particular higher than other imputation methods for the data with high missing rates and large number of experiments. Application of Expectation Maximization (EM) to the SKNN method improved the accuracy, but increased computational time proportional to the number of iterations. The Multiple Imputation (MI) method, which is well known but not applied previously to microarray data, showed a similarly high accuracy as the SKNN method, with slightly higher dependency on the types of data sets. Sequential reuse of imputed data in KNN-based imputation greatly increases the efficiency of imputation. The SKNN method should be practically useful to save the data of some microarray experiments which have high amounts of missing entries. The SKNN method generates reliable imputed values which can be used for further cluster-based analysis of microarray data.