• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.354.1-354.1
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• 2016

Nanoporous gold (NPG) is a very promising material in various fields such as sensor, actuator, and catalysis because of its high surface to volume ratio and conducting nature. In this study, we fabricated a NPG based amperometric sensor on a glass substrate by means of co-sputtering of Au and Si. During the sputtering process, we found the optimum conditions for heat treatment to reduce the residual stress and to improve adhesion between NPG films and the glass substrate. Subsequently, Si was selectively etched from Au-Si alloy by KOH solution, which forms nanoporous structures. Scanning electron microscopy (SEM) and auger electron spectroscopy (AES) were used to estimate the structure of NPG films and their composition. By employing appropriate heat treatments, we could make very stable NPG films. We tested the performance of NPG sensor with aniline molecules, which shows high sensitivity for sensing low concentration of aniline.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.87-90
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• 1991

In the field of structural analysis so-called substructure methods have been applied extensively to solve large and complex structures by splitting them up in substructures. This substructure method is applicable to electromagnetic field analysis and highly parallel in nature. In this paper substructure FEM is implemented for magnetostatic field computation using parallel computer consists of many transputers. Parallel substructure method is a promising tool as a solution of not only compuation speed problem but also memory problem.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.331-336
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• 2002

Recently the critical nozzles with small diameter are being extensively used to measure mass flow in a variety of industrial fields and these have different configurations depending on operation condition and working gas. The curvature radius of the critical nozzle throat is one of the most important configuration factors promising a high reliability of the critical nozzle. In the present study, computations using the axisymmetric, compressible, Navier-Stokes equations are carried out to investigate the effect of the nozzle curvature on critical flows. The diameter of the critical nozzle employed is D=0.3mm and the radius of curvature of the critical nozzle throat is varied in the range from 1D to 3D. It is found that the discharge coefficient is very sensitive to the curvature radius(R) of critical nozzle, leading to the peak discharge coefficient at R = 2.0D and 2.5D, and that the critical pressure ratio increases with the curvature radius.

• Journal of the Korean Electrochemical Society
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• v.13 no.1
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• pp.10-18
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• 2010

Nanostructured metal oxides have been widely used in the research fields of photoelectrochemistry, photochemistry and opto-electronics. Dye-sensitized solar cell is a typical example because it is based on nanostructured $TiO_2$. Since the discovery of dye-sensitized solar cell in 1991, it has been considered as a promising photovoltaic solar cell because of low-cost, colorful and semitransparent characteristics. Unlike p-n junction type solar cell, dye-sensitized solar cell is photoelectrochemical type and is usually composed of the dye-adsorbed nanocrystalline metal oxide, the iodide/tri-iodide redox electrolyte and the Pt and/or carbon counter electrode. Among the studied issues to improve efficiency of dye-sensitized solar cell, nanoengineering technologies of metal oxide particle and film have been reviewed in terms of improving optical property, electron transport and electron life time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.142-148
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• 2015

3D printing technology is a promising technique for fabricating complex 3D architectures based on the CAD/CAM system, and it has been extensively investigated to manufacture structures in the fields of mechanical engineering, space technology, automobiles, and biomedical and electrical applications. Recent advances in the 3D printing of soft structures have received attention for the application of the construction of flexible sensors of soft robotics or the recreation of tissue/organ-specific microenvironments. In this review paper, we would like to focus on delivering state-of-the-art fabrication of soft structures with 3D printing technology and its various applications.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.5
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• pp.523-529
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• 2009

Smart sensor is known as intelligent sensor, it is different with other conventional sensors in the case of intelligent system embedded on it. Smart sensor has many benefits e.g. low-cost in usage, self-decision and self-diagnosis abilities. This sensor consists of perception element(sensing element), signal processing and technology of communication. In this work, a bridge and structure of smart sensor has been investigated to be capable to condition monitoring routine. This investigation involves low power consumption, software programming, fast data acquisition ability, and authoritativeness warranty. Moreover, this work also develops smart sensor to be capable to perform high sampling rate, high resolution of ADC, high memory capacity, and good communication for data transfer. The result shows that the developed smart sensor is promising to be applied to various industrial fields.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.62-62
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• 2011

Intramolecular charge transfer (ICT) system has received great attentions due to their promising optoelectronic properties For the efficient ICT of the chromophore, their organic compound mainly consists of strong electron donors (e.g. $NR_2$ or OR groups) and acceptors (e.g. CN or $NO_2$ groups). According to the molecular design and synthesis, the ICT compounds can be extended in many application fields. In this study, we have synthesized ICT compounds having a strong electron acceptor and donor. These novel ICT compounds were easily synthesized by a previously described method with some modifications. Their single crystals were grown and their structures were solved and described in this presentation.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.1
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• pp.1-9
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• 1998

In a competitive environment, systems design should be agile to accomplish business goal. However, there are often significant problems with systems design that is manifested in the fact that there are no current techniques to apply rigorous mathematics to semantic conveyance in the design framework. As a promising solution, this paper introduces situation theory (ST) and provides an application of ST for information flow in manufacturing systems design (IDEF0). The described work in this paper addresses the procedure of creation of IAST Model (Inf-Act On in Situation Theory) which is the first application of ST in engineering fields. Finally, we show that IAST Model is very helpful for effective information capturing in systems by comparison existing methodology with developed methodology as a practical application of ST.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.502-505
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• 2007

PMMA has been extensively adopted in Nano Imprint Lithography(NIL). PMMA nano-structures experience severe mechanical load and deformation during NIL process, and understanding its mechanical behavior is very important in designing and optimizing NIL process. One of the most promising techniques for characterizing the mechanical behavior of nano structures is nano pillar compression test. In this study, the mechanical behaviors of PMMA pillars during compression test are analyzed using Molecular Dynamics. Two methods for simulation of PMMA nano pillars are proposed. The stress-strain relationship of nano-scale PMMA structure is obtained based on CVFF(Covalent Valence Force Fields) potential and the dependency of the applied strain rate on the stress-strain relationship is analyzed. The obtained stress-strain relationships can be useful in simulating nano-scale PMMA structures using Finite Element Method(FEM) and understanding the experimental results obtained by compression test of PMMA nano pillars.

• Environmental Engineering Research
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• v.19 no.4
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• pp.299-308
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• 2014

This study presents a review on Chemical looping combustion (CLC) development, design aspects and modeling. The CLC is in fact an unmixed combustion based on the transfer of oxygen to the fuel by a solid oxygen carrier material avoiding the direct contact between air and fuel. The CLC process is considered as a very promising combustion technology for power plants and chemical industries due to its inherent capability of $CO_2$ capturing, which avoids extra separation costs of the of $CO_2$ from the rest of flue gases. This review covers the issues related to oxygen carrier materials. The modeling works are reviewed and different aspects of modeling are considered, as well. The main drawbacks and future research and prospects are remarked.