• Journal of the Korean institute of surface engineering
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• v.17 no.2
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• pp.29-40
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• 1984

The structure of rapidly solidified Al-Si-based alloys and its relationship to subsequent anodic film growth in near neutral and acid solutions have been investigated. Solidification of the alloys proceeds via pre-dendritic nuclei, associated with rugosity of the casting surface, from which cellular-type growth, comprised of aluminium-rich material surrounded by silicon-containing material, emanates. Observation of ultramicrotomed sections of the alloys and their anodic films reveals the local oxidation of the silicon-rich phase and its incorporation into the anodic alumina film, formed in near neutral solutions. Such incorporation occurs but resultant isolation of the silicon-rich phase is not possible for anodizing in phosphoric acid, and a three-dimensional network of the oxidized silicon-containing phase, with continuing development of porous anodic alumina, is observed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1100-1103
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• 2004

The paper presents the results of using the fundamental and the low frequency harmonic components of leakage current to study aging of EPDM insulator for contaminated condition by kaolin. The largeer the leakage current during 200ms, the higher harmonic component at 60hz. The harmonic component at 60hz and the odd order harmonics is increase relation without Kaolin Conent. Arcing on the surface was always associated with distortion in the leakage current; hence the low frequency components of the leakage currnent can be used as a means to evaluate the surface degration. Both the fundamental and 3rd & 5th harmonics increase dry-band activity.

• Carbon letters
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• v.5 no.4
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• pp.191-196
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• 2004

The electrochemical removal (ECR) of water pollutants by activated carbon fiber (ACF) electrodes from wastewater was investigated over wide range of electrochemical reaction time. The ECR capacities of ACF electrodes were associated with their internal porosity and were related to physical properties and to reaction time. And, surface morphologies and elemental analysis for the ACFs after electrochemical reaction are investigated by SEM and EDX to explain the changes in adsorption properties. The FT-IR spectra of ACFs for the investigation of functional groups show that the electrochemical treatment is consequently associated with the homogeneous removal of pollutants with the increasing surface reactivity of the activated carbon fiber surfaces. The ACFs were electrochemically reacted to waste water to investigate the removal efficiency for the COD, T-N and T-P. From these removal results of pollutants using ACFs substrate, satisfactory removal performance was obtained. The outstanding removal effects of the ACFs substrate were determined by the properties of the material for adsorption and trapping of organics, and catalytic effects.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.417-422
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• 2009

The problems associated with the synthesis, characterization and application of $SnO_2$-Au nanocomposites for the optimization of conductometric gas sensors have been discussed in this report. Nanocomposites have been synthesized on the surface of $SnO_2$ films using successive ionic layer deposition(SILD) method. It has been shown that the proposed approach to surface modification of metal oxide films is an excellent method for the optimization of the operating characteristics of $SnO_2$-based gas sensors, being developed for the detection of reducing gases as well as ozone.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.452-452
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• 2008

Abstract Head-mounted displays(HMD) are being developed and marketed in growing numbers for a variety of applications. Though most commonly associated with entertainment applications other applications are also being developed. The field vision on the display screens is expanded by the optical system producing an imaginary screen that appears to be positioned several meters in front of the viewer. In this study, the mold core for the prism lens of HMD was processed by fly-cutting method, and the form accuracy of the mold core was measured.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.156-162
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• 1995

For a stimulating neural electrode, the charge density should be as large as possible to provide adequate stimulation of the nervous system while allowing for miniaturization of the electrode. Since iridium oxide is able to produce high charge densities while preventing undesirable reactions due to charge storage, it has become a promising material for neural prostheses. Successful production of stable Ir and Ir oxide films on various substrates now limits the use of this material. Ir was deposited on two differently prepared surface of (mirror finish, passivation) surgical Ti-6AI-4V with several methods. Ion beam mixing of sputter deposited Ir films on passivated Ti-6AI-4V produced stable and good adherent Ir films. It was found that the increase in charge density of pure Ir on continuous cyclingis due to the accumulation of the oxide phase ( associated with a large surface area) in which the valence state of iridium changes and the double-layer capacitance increases. This study also showed that the double layer capacitance is equally or even more responsible for the high charge density of anodically formed Ir oxide.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.345-348
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• 2012

The optical losses associated with the reflectance of incident radiation are among the most important factors limiting the efficiency of a solar cell. Therefore, photovoltaic cells normally require special surface structures or materials, which can reduce reflectance. In this study, nano-scale textured structures with anti-reflection properties were successfully formed on silicon. The surface of sicon wafer was etched by the inductively coupled plasma process using the gaseous mixture of $SF_6+O_2$. We demonstrate that the reflection characteristic has significantly reduced by ~0% compared with the flat surface. As a result, the power efficiency $P_{max}$ of the nano-scale textured silicon solar cell were enhanced up to 20%, which can be ascribed primarily to the improved light trapping in the proposed nano-scale texturing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.39-40
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• 2009

The patterned vertical alignment (PVA) display showed good electro-optic properties such as wide viewing angle, fast response time, high Contrast Ratio. However, the device has patterned electrode on both top and bottom electrodes which requires high accuracy of assembling of top and bottom substrates in order to exhibit a high performance. So, they have disadvantage about low yield. In order to resolve these problem, in this paper, we studied about top substrate pattern free vertical alignment device associated with surface polymer stabilization using the UV curable monomer. This method shows simple progress, low cost and good electro-optic properties such as high transmittance and fast response time.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.779-784
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• 2013

Increased efficiency and improved performance associated with light-weight materials were investigated in this study. Numerous studies have investigated surface treatments to improve the fatigue strength of metals. Laser heat treatment is a promising method because the power and spot size can be easily controlled, allowing a small heat affected zone (HAZ). However, changes in the material properties can result; in particular, the material can become more brittle. In this study, a combination of laser heat treatment and vibration peening was proposed to increase fatigue strength without changing the material characteristics. SCM440H was investigated experimentally, and specimens were tested using a giga-cycle ultrasonic fatigue tester. The results show that the combination of these two processes significantly increased the fatigue strength and, furthermore, different fracture types were observed after a small and large number of cycles.

• Korean Institute of Interior Design Journal
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• v.13 no.4
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• pp.83-91
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• 2004

This study focuses on defining the new meaning of immateriality in the present times expressed on space. The purposes of this study were to examine the characteristics of immateriality showed in commercial interior design in Korea, based on the definition of immateriality concept and the analysis of the way it is expressed. The result of this study is as follows; it categorized characteristic of material expression, space concept and media. Characteristic elements can be classified into 6: transparency, implication, off-gravitation, ambiguity of boundary, temporality, interactivity. Expression of immateriality in commercial interior space was obtained in many different ways, which are identified: new expression of material by reduction of materiality, leveling of transparency, expression of floating status, changeable image, illusion effect, blurring boundary. Immateriality is deeply associated with the elements such as surface, material, media, light, and movement. So it is being recognized as an important design concept in today's pluralist society and will play an important role within the design paradigms for the future.