• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.06a
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• pp.102-103
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• 2005

Using THz time-domain spectroscopy, we study plasmonic band gaps in periodic metal arrays of slits. Femtosecnd machining system guarantees good quality sub millimeter structures for THz spectroscopy. Fabry-Perot effect enhances the transmission when the two resonances cross but does not alter the surface plasmon peak positions.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1081-1083
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• 2007

The study in river basin has been performed for the identify water quality impaired stream segments, to create a priority ranking of those segments, and to calculate the heavy metal ion distribution for each impaired segment based on chemical and physical water quality standards. Two methods for modeling the potential area-specific heavy metal distribution are pursued in this study. First, a novel approach focuses on distance. Heavy metal distribution can be associated with a particular small geographic area. Based on the derived estimates an distribution map can be generated. Second, the approach is used the near watershed by means of kriging interpolation algorithm. These approaches provide an alternative distribution mapping of the area. The exposure estimates from both of these modeling methods are then compared with other environmental monitoring data. A GIS-based model will be used to mimic the hierarchical stream structure and processes found in natural watershed. Specifically, the relationship between landscape variables and reach scale habitat conditions most influential found in the Abandoned mine will be explored.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.925-929
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• 2005

Some new metal(II) complexes, $M^{II}L_2$ [M = Mn (1), Co (2), Ni (3), Cu (4), and Zn (5)] of 2-acetylpyridine benzoylhydrazone ligand (HL) containing trifunctional NNO-donor system have been synthesized and crystallographically characterized for the complex 1 and 5. The complexes consist of two ligands to give sixcoordinate, which are bonded to the metal atom on a meridional plane through acetylpyridine ring nitrogen, azomethine nitrogen, and benzoyl oxygen atoms, respectively. The coordination geometry for other complexes was identified on the basis of the physicochemical data by elemental analyses, FAB -MS, IR, $^1H$ NMR, and electronic spectral measurements. The resulting data indicated that the complexes are accordance with the above formulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.689-693
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• 1996

This paper was performed on the automatic selection of cutting condition on multispindle machine. the several mathematical relationships were formulated for simulataneous selection of machining parameters and tool changing scheme. In this research we used two step generative approach; step 1 is mathematical modeling for the selection of optimal cutting conditions and the other is GMDH-TYPE modeling to find prediction equation of system performance. thus in this paper, mathematical machining models combined with a heuristic GMDH-TYPE modeling to estimate the system performance, these models are developed computer programs for practical application and it was shown that the proposed approach has a good potential and offers a valuable tools to performance evaluation for metal cutting system.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.185-191
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• 2016

Purpose: The purpose of this study were to evaluate the quality of dental prostheses printed by 3-dimensional printing system. Methods: Mater model was prepared and ten study models were fabricated. Ten single crowns were printed by 3D-printing system(Resin group) and another ten single crowns using casting method were manufactured(Metal group). The marginal adaptation of single crowns were measured using by silicone replica technique. Silicone replicas were sectioned four times. The marginal adaptations were evaluated using by digital microscope. Statistical analyses were performed with Mann-Whitney test(${\alpha}=0.05$). Results: $Mean{\pm}standard$ deviations of all marginal adaptations were $92.1(20.0){\mu}m$ for Metal group and $69.7(12.3){\mu}m$ for Resin group. Two groups were no statistically significant differences(p>0.05). Conclusion: Marginal adaptation of single crowns printed by 3D-printing system were ranged within the clinical recommendation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.2
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• pp.213-220
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• 1999

The purpose of this study is to apply cathodic protection to reinforced concrete structure and provide fundamental data to prevent the corrosion. The theory of cathodic protection of steel in concrete is to apply sufficient direct current so that corroding anodes on the steel are prevented from discharging ions. Two methods are used to supply the external current. In one, the protected metal is the cathode by connecting it to a more active metal. In the second, an external direct current power source supplies the current. The first is the sacrificial-anode system and the second the impressed-current system. The study results showed that the corrosion of the reinforcing steel in concrete could be enormously decreased by using protective current. The sacrificial anode and concrete nave to be adhered closely each in order to prevent the corrosion of reinforcing steel.

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.96-101
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• 2005

A theory for the material transports through ion exchange membrane has been developed on the basis of nonequilibrium thermodynamics by removing the assumption of solvent flow in the previous paper and applied to a detailed study of the ionic transport properties of new charged mosaic membrane(CMM) system. The CMM having two different fixed charges in the polymer membrane indicated unique selective transport behavior then ion-exchange membrane. The separation behavior of ion transport across the CMM with a parallel array of positive and negative functional charges were investigated. It was well-known the analysis of the volume flux and solute flux based on nonequilibrium thermodynamics. Our suggests preferential salt transport across the charged mosaic membranes. Transport properties of heavy metal ions, $Mg^{2+}$, $Mn^{2+}$and sucrose system across the charged mosaic membrane were estimated. As a result, we were known metal salts transport depended largely on the CMM. The reflection coefficient indicated the negative value that suggested preferential material transport and was independent of charged mosaic membrane thickness.

• Advances in materials Research
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• v.2 no.4
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• pp.181-193
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• 2013

Description and theory of spin coating technique has been elaborately outlined and a spin coating machine designed and fabricated using affordable components. The system was easily built with interdisciplinary knowledge of mechanics, fluid mechanics and electronics. This equipment employs majorly three basic components and two circuit units in its operation. These include a high speed dc motor, a proximity sensor mounted at a distance of about 15 mm from a reflective metal attached to the spindle of the motor to detect every passage of the reflective metal at its front and generate pulses. The pulses are transmitted to a micro-controller which process them into rotational speed (revolution per minute) and displays it on a lead crystal display (LCD) which is also a component of the micro-controller. The circuit units are a dc power supply unit and a PWM motor speed controlling unit. The various components and circuit units of this equipment are housed in a metal casing made of an 18 gauge black metal sheet designed with a total area of 1, $529.2cm^2$. To illustrate the use of the spin-coating system, ZnO sol-gel films were prepared and characterized using SEM, XRD, UV-vis, FT-IR and RBS and the result agrees well with that obtained from standard equipment and a speed of up to 9000 RPM has been achieved.

• Transactions on Electrical and Electronic Materials
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• v.12 no.4
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• pp.131-134
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• 2011

Back-end-of-line using ultra low-k (ULK; k < 2.5) has been required to reduce resistive capacitance beyond 45 nmtechnologies, because micro-processing units need higher speed and density. There are two strategies to manufacture ULK inter-layer dielectric (ILD) materials using an air-gap (k = 1). The former ULK and calcinations of ILD degrade the mechanical strength and induce a high cost due to the complication of following process, such as chemical mechanical polishing and deposition of the barrier metal. In contrast, the air-gap based low-k ILD with a relatively higher density has been researched on the trench-type with activity, but it has limited application to high density devices due to its high air-gap into the next metal layer. The height of air-gap into the next metal layer was reduced by changing to the via-typed air-gap, up to about 50% compared to that of the trench-typed air-gap. The controllable ULK was easily fabricated using the via-typed air-gap. It is thought that the via-type air-gap made the better design margin like via-patterning in the area with the dense and narrow lines.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.47-76
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• 1994

This study was carried out to evaluate the effect of the crack propagation characteristics and bond stress of ceramo-metal system. In order to characterize the crack propagation, the static crack propagation stored in $37^{\circ}C$ distilled water of two commerical porcelains and the dynamic crack propagation under cyclic flexure load of ceramo-metal system were examined. In order to characterize the bond stress, the shear bond test, the 3-point flexure bond test, and the finite element stress analysis of ceramo-metal system were conducted. The results obtained were as follows : 1. Bulk densities and Young's moduli of opaque porcelains increased with repeated firing. 2. Maximum fracture toughness during 4 firing cycles showed at the group of 4 firing cycles in Ceramco porcelain and 2 firing cycles in Vita porcelain. 3. Shear bond strength and flexure bond strength of Ceramco-Verabond specimen were larger than those of Ceramco-Degudent G specimen (p<0.05). 4. Interfacial stresses under three point flexure bond test were concentrated at the edges of ceramometal system. 5. When a cyclic flexure load was applied, the crack growth rate of porcelain surface of ceramometal specimens was decreased as load cycles increased.