Interfacial Reactions and Microstructures of Sn-0.7Cu-<Emphasis Type="Italic">x</Emphasis>Zn Solders with Ni-P UBM During Thermal Aging

The effects of the addition of Zn to Sn-0.7Cu solders are investigated. The study is focused on the interfacial reactions, microstructures, and mechanical properties after reaction with Ni-P under bump metallurgies (UBMs). The Zn contents in Sn-0.7Cu-xZn are varied as 0.2, 0.4, and 0.8 (in wt.% unless otherwise specified). In the reaction with Ni-P UBM during thermal aging at 150°C for 1000 h, (Cu,Ni)₆Sn₅ intermetallic compounds (IMCs) are formed at the Sn-0.7Cu/UBM interface, whereas Zn is incorporated into IMCs to form (Cu,Ni,Zn)₆Sn₅ in the Zn-doped solders. As the Zn content increases, the interfacial IMC thickness is reduced. A total reduction of about 40% in IMC thickness was observed for the 0.8% Zn-doped Sn-Cu. The same IMC particles are also observed in the matrix of each solder. In Sn-0.7Cu, (Cu,Ni)₆Sn₅ particles are coarsened during aging, while (Cu,Ni,Zn)₆Sn₅ particles in the Zn-added solders are less coarsened and remain much smaller than (Cu,Ni)₆Sn₅. The growth rate of (Cu,Ni)₆Sn₅ during thermal aging is significantly suppressed by the addition of Zn. Consequently, after reaction with Ni-P UBM, the Zn-doped solders exhibit a thermally stable microstructure as measured by hardness and shear strength.     

Feature Detection and Simplification of 3D Face Data with Facial Expressions

We propose an efficient framework to realistically render 3D faces with a reduced set of points. First, a robust active appearance model is presented to detect facial features in the projected faces under different illumination conditions. Then, an adaptive simplification of 3D faces is proposed to reduce the number of points, yet preserve the detected facial features. Finally, the point model is rendered directly, without such additional processing as parameterization of skin texture. This fully automatic framework is very effective in rendering massive facial data on mobile devices.     

Welding strain analysis of friction stir-welded aluminum alloy structures using inherent strain-based equivalent loads

Friction stir welding is a solid-state welding method commonly used for aluminum alloy or lightweight metal. It has the advantages of low welding strain, high welding quality, and low residual welding stress while requiring no protection gas. Welding strain analysis of friction stir welding using finite element analysis has been the subject of many studies that focused on the substance fluid using threedimensional computational fluid dynamics; however, this approach is inefficient for large structures and requires much time for analysis. To address this drawback, this study proposes a faster method for analyzing extruded aluminum material that exploits the advantages of the inherent strain-based equivalent load.     

Rapid dye adsorption for dye-sensitized solar cells using a simple ultrasonication method

The dye adsorption process for dye-sensitized solar cells (DSSCs) is the most rate limiting step, usually consuming up to 24 h depending on the film thickness and particle size. In this study, we propose a simple and effective method to reduce the dye adsorption time using a general bath-type ultrasonic device. Applying the ultrasonication method, the dye adsorption time was much reduced compared to the conventional dipping method for the full uptake of dye molecules. For further studies, the sole effect of solution temperature on the dye adsorption was also investigated due to the solution temperature increase during the ultrasonication process. The UV and IR absorbance analyses were performed to detect the possible structural changes of dye molecules during the ultrasonication process.     

A computational strategy for doubly smoothed MLE exemplified in the normal mixture model

A typical problem for the parameter estimation in normal mixture models is an unbounded likelihood and the presence of many spurious local maxima. To resolve this problem, we apply the doubly smoothed maximum likelihood estimator (DS-MLE) proposed by Seo and Lindsay (in preparation). We discuss the computational issues of the DS-MLE and propose a simulation-based DS-MLE using Monte Carlo methods as a general computational tool. Simulation results show that the DS-MLE is virtually consistent for any bandwidth choice. Moreover, the parameter estimates in the DS-MLE are quite robust to the choice of bandwidths, as the theory indicates. A new method for the bandwidth selection is also proposed.     

Ontology-based fuzzy support agent for ship steering control

The important field of research on ship operation is related to the high efficiency of transportation, the convenience of maneuvering ships, and the safety of navigation. This paper proposes an ontology-based fuzzy support agent for ship steering control and desires to testify the validity of the proposal by applying the fuzzy control model to the steering control system based on linguistic instruction. The fuzzy support agent is presented to build the maneuvering models of steersman and the miniature model for steering control system. The proposed fuzzy agent contains three main mechanisms, including the interpretation mechanism of linguistic instruction, the self-regulation mechanism, and the task performance mechanism. Furthermore, the task performance mechanism includes the kinematics module and the performance ontology. The simulation results show that the proposed approach can work effectively for ship steering control.     

Aspergillus oryzae strains isolated from traditional Korean Nuruk: Fermentation properties and influence on rice wine quality

Forty-seven strains of Aspergillus oryzae isolates from Korean nuruks were compared for their brewing characteristics. A. oryzae YI-A6 and YI-A7 showed the highest acid α-amylase, glucoamylase, and carboxypeptidase activities, respectively. Sixteen isolates with high amylolytic or proteolytic enzyme activities were selected for investigation of their rice wine fermentation characteristics. After 12 days of brewing at 15°C, ethanol concentrations were 10.2–14.3% for A. oryzae strains. Fermentation rates were the highest for YI-A7. Most rice wine samples fermented with nuruk strains had lower concentrations of off-flavor compounds than the control did. All mean sensory attribute values significantly differed among samples. Pearson correlation coefficients showed that glucoamylase activity was positively correlated to both ethanol productivity and overall harmony (p<0.01). Thus, glucoamylase activity was identified as the best factor for screening Aspergillus strains for use in rice wine brewing.     

Correlation of Microstructure and Cracking Phenomenon Occurring during Hot Rolling of Lightweight Steel Plates

An investigation was conducted into the correlation of microstructure and the cracking phenomenon that often occurred in hot-rolled lightweight steel plates. Two kinds of steels were fabricated with varying Mn and Al contents, and their microstructures, tensile properties, and high-temperature transformation behavior were investigated. In the two steels, banded structures containing ferrite grains and κ-carbides were well developed along the rolling direction. Detailed microstructural analyses showed that cracks initiated at film-type κ-carbides continuously formed interfaces between bands, while the band populated with κ-carbides did not play an important role in initiating cracks. Thus, the formation of band structures and film-type interfacial κ-carbides must be minimized to prevent the cracking. The decreased content of hardenability elements, including aluminum, higher finish-rolling temperature, reduced central segregation during the slabmaking process, and decreased material variation during hot rolling, were suggested as practical methods for preventing the cracking.