Ki Bong Song

Field emission induced fabrication of nanostructures on Au thin films using a noncontact mode atomic force microscope

We report a reliable nanofabrication on Au cluster films using an atomic force microscope (AFM) without the occurrence of tip damage or serious mass transfer between tip and sample. Noncontact mode of AFM equipped with W2C coated tip is used, and the field emission current amounting to ∼500 pA is observed, indicating the noncontact nature of our nanofabrication method. We reproducibly create dots and lines having widths as small as 50 nm. The mechanism is explained by effective local heating due to the low thermal conductivity of granular Au films and by concurrent field induced diffusion of Au clusters.

In Situ Curing of Sliding SU-8 Droplet over a Microcontact Printed Pattern for Tunable Fabrication of a Polydimethylsiloxane Nanoslit

A tunable process for polydimethylsiloxane (PDMS) nanoslit fabrication is developed for nanofluidic applications. A microcontact printing (μCP) of a laterally spreading self-assembled hexadecanethiol (HDT) layer, combined with in situ curing of a sliding SU-8 droplet, enables precise and independent tuning of a nanoslit-mold width and height using a single μCP master mold. The SU-8 nanoslit-mold is replicated using a hard-soft composite PDMS to prevent channel collapse at low (<0.2) aspect ratio (height over width). The fluidic characteristics as well as dimensions of nanoslits fabricated with various conditions are analyzed using a fluorescein sample and AFM images. Finally, concentration polarization-based sample preconcentration is successfully demonstrated at the nanoslit boundary where an electric double-layer is overlapped.

A preemptible resource management scheme on multimedia processing cloud systems

In this paper, we propose the alternative resource allocation scheme to implement VM(virtual machine) manager for multimedia processing applications on the cloud system. The proposed scheme provides a selectively preemptible resource allocation approach to reduce the client service waiting time on the cloud based network systems. For the performance evaluation, various reference schemes are adopted to compare the multidimensional resource allocation problem. In comparison with the reference schemes, the proposed scheme with new constrains shows better performance results in reducing the client waiting time and the waiting queue length of client tasks on the cloud system.

Distributed sensor device resource-object connection based on service delivery platform

A system for providing a distributed device resource-object-connection service based on a service delivery platform (SDP) is described. The system includes an SDP and proxy. The SDP configures to define distributed service functions as enablers, generates a convergence service by combining the enablers, and provides the generated convergence service. The proxy configures to connect a distributed device and an SDP to allow the SDP to use the distributed device as a resource, and define and use the distributed device as an enabler. The system are capable of defining distributed service functions as well as distributed sensors as enablers, and thereby allowing the distributed sensors to be used in the same sense as service-function enablers.

Non-collapsible PDMS nanochannel fabrication with tunable width and height using single master mold

A tunable polydimethylsiloxane (PDMS) nanoslit fabrication process was developed for biological sample manipulation. A microcontact printing (µCP) of laterally spreading self-assembled hexadecanethiol (HDT) layer, combined with in-situ curing of a sliding SU-8 droplet, enabled precise and independent tuning of a nanoslit-mold width and height using single µCP master mold. The SU-8 nanoslit-mold was replicated using a hard-soft composite PDMS to prevent channel collapse at low ( &#60; 0.2) aspect ratio (height over width). The fluidic characteristics as well as dimensions of nanoslits fabricated with various conditions are analyzed using fluorescein sample and AFM images. Finally, concentration polarization-based sample preconcentration is successfully demonstrated at the nanoslit boundary where an electric double layer is overlapped.

A Simple Method for Quantification of Beta-Amyloid Using the Photo-Sensitive Thin Film Transistor

This paper reports a technique for quantification of beta-amyloid protein by the use of photo sensitive thin film transistor (p-TFT). In recent studies, a beta-amyloid protein has strongly related a central role of the pathogenesis of Alzheimer’s disease (AD) and AD-related olfactory sensory loss. In the p-TFT, we observed the difference of the photo-current according to the presence of the particles with beta-amyloid, RAW 264.7 cells, and olfactory receptor neuron cells. The p-TFT shows the drain current reduction of about 50μA is caused by the RAW 264.7 cells with magnetic beads and beta-amyloid. Therefore, we suggest a new method of detecting small quantity of A-beta for early diagnosis of AD by using photo-sensitive thin film transistor (p-TFT) devices.

Structural quality of CIGS absorber layers via powder evaporation and solution spray deposition

In this study, we have prepared the Cu(InGa)Se2 (CIGS) thin film absorber layers by evaporation of CIGS powders and solution spray deposition with different atomic ratio compositions. High quality and well faceted chalcopyrite thin films were obtained by these simple deposition processes. CIGS absorber thin films were grown with polycrystalline chalcopyrite structures with preferred orientation of (112) directions. Our results showed that CIGS powder evaporation and solution spray deposition processes are promising candidate for the solar cell grade CIGS thin film absorber layer depositions.