• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1988.11a
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• pp.35-48
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• 1988

상대 접촉하고 있는 물체에 미끄럼 운동이 가해질 경우 마찰에 의해 발생되는 거의 모든 에너지는 열로써 나타나게 된다. 이러한 마찰열은 주로 adhered junctions의 파괴 및 표면돌기(surface asperities)들의 소성 변형에 의한 열역할적 비가역 반응의 결과로 발생된다. 접촉부위의 발생열은 양 접촉제의 접촉면에 전달되어 접촉표면 온도의 급격한 증가를 초래하며 그 결과로 여러가지 surface phenomena, 즉 마찰, 마모, 산화(oxidation), 부식 및 구조적 열화(structural degradation) 금속학적 상변화등에 큰 영향을 미치게 된다. 딸서 볼 및 로울링 엘레먼트 베어링, 기어, 캠과 태핏, 브레이크 등 기계요소의 설계를 위한 주인자로서 근래에 들어 접촉표면의 온도가 주목받고 있다. 표면에 존재하는 layer로서는 금속표면에 응착시킨 coating layers, contaminant films, physisorbed 또는 chemisorbed films, oxide layers 또는 마찰열에 의해 형성되는 경도가 아주 높은 내마모층(hard wear-resistant layers) 등이 고려될수 있다. 낮은 열전도성을 가진 oxide film이 접촉 표면이 온도를 증가시킨다는 것이 Jaeger에 의해 지적되었으며 Ling과 Lai는 moving heat sjource가 가해지는 layered surface의 표면온도분포를 구하면서 substrate와 thermal property가 다른 layer가 존재하게 되면 그 두께가 아주 얇더라도 (1 마이크론 정도) 표면온도는 크게 변화됨을 보였다.

• Corrosion Science and Technology
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• v.5 no.1
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• pp.15-22
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• 2006

The introduction of two-grid inside a conventional process system produces a reactive coating deposition and increases metal ion ratio in the plasma, resulting in denser and smoother films. The corrosion behaviors of TiN coatings were investigated by electrochemical methods, such as potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in deaerated 3.5% NaCl solution. Electrochemical tests were used to evaluate the effect of microstructure on the corrosion behavior of TiN coatings exposed to a corrosive environment. The crystal structure of the coatings was examined by X-ray diffractometry (XRD) and the microstructure of the coatings was investigated by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). In the potentiodynamic polarization test and EIS measurement, the corrosion current density of TiN deposited by two grid-attached magnetron sputtering was lower than TiN deposited by conventional magnetron type and also presented higher Rct values during 240 h immersion time. It is attributed to the formation of a dense microstructure, which promotes the compactness of coatings and yields lower porosity.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.229-234
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• 1997

Recently many concrete structures have been deteriorated due to the corrosion of reinforcing steel caused by chloride attack. The chloride attack causes very rapid and serious deterioration. Therefore, It is necessary for highly reliable method to stop the corrosion. Especially, on damaged concrete, it is difficult to stop the progress of steel corrosion that has already occured in concrete. The indirect method of corrosion protection such as eliminating corrosion factors by coating would be hard to be expected for complete stop of corrosion. In this paper, we applied the cathodic protection to chloride attacked marine concrete structures and verified the effect in addition to application of cathodic protection.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.267.1-267.1
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• 2013

In modern science and technology, the organization of building blocks, such as spherical particles and zeolite, is important to form a nanostructure. So, it is essential to develop methods for organizing them into large scale for many precise applications. Up to now, reflux and stirring is widely used method for organization of colloidal particles. However, because this method is hard to organize building block with high coverage and uniform orientation, it is necessary to research another method. In this work, we synthesized spherical silica particles using St$\"{o}$ber method and organized them on the glass which is coated with 3-chloropropyltrimethoxysilane (CP-TMS) and polyethyleneimine (PEI) using Sonication method. Although spherical silica particles are difficult to attach on the glass due to their small attachment site, we improved this problem by coating PEI. We introduced two mode of reaction promotion, sonication (SO) and sonication with stacking between the bare glass (SS), and investigated degree of coverage (DOC) and degree of close packing (DCP).

• Current Optics and Photonics
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• v.1 no.1
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• pp.45-50
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• 2017

Optical instruments based on polymer-dispersed liquid crystal (PDLC) have been used to inspect transparent electrodes. Generally the operating voltage of an inspection instrument using PDLC is very high, over 300 V, reducing its lifetime and reliability. The operating-voltage issue becomes more serious in the inspection of touch-screen panel (TSP) electrodes, due to the bezel structure protruding over the electrodes. We have theoretically calculated the parameters affecting the operating voltage as a function of the distance between the TSP and the PDLC, the thickness, and the dielectric constant of the sublayers when the inspection module was away from the TSP electrodes. We have experimentally verified the results, and have proposed a way to reduce the operating voltage by substituting a plastic substrate film with a hard coating layer of smaller thickness and higher dielectric constant.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.417-424
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• 2022

This research develops an easy-to-use, environmentally friendly method for fabricating functional 1050 aluminum alloy surfaces with excellent corrosion resistance. Functional aluminum surfaces with various nanostructures are fabricated by controlling the experimental conditions of anodizing process. The experiment used a multi-step anodizing process that alternates between two different anodizing modes, mild anodizing (MA) and hard anodizing (HA), together with a pore-widening (PW) process. Among them, the nanostructured surface with a small solid fraction shows superhydrophobicity with a contact angle of more than 170° after water-repellent coating. In addition, the surface with superhydrophobicity is difficult for corrosive substances to penetrate, so the corrosion resistance is greatly improved.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.2
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• pp.66-73
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• 2022

Partial-hardened hot stamping has been well known to be very effective to absorb more energy in automotive lateral crash. Hardness distribution and dimensional change after partial-hardened hot stamping have been studied to find out effect of thermal deformation of the heated hot stamping die on dimensional accuracy of automotive center pillar. Soft zone of commercial center pillar showed 275~345 in Vickers hardness, indicating bigger non-uniformity which resulted from thermal deformation of heated die. Dimensional changes in soft zone of the commercial center pillar measured by three dimensional scanner were much bigger than that in hard zone. It has been found that hot stamping die compensation considering thermal deformation in soft zone causes a significant decrease in hardness deviation in the soft zone, corresponding to 20 percent of commercial center pillar and subsequently leads to much higher dimensional accuracy.

• Journal of the Korean institute of surface engineering
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• v.31 no.6
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• pp.334-344
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• 1998

Yew coating pmccss t.o form a surface layer ol CrN phasc on mild steel (A81 1020!, AlSI Hi3, 1Cr-0.5Mo steel (ASTM A213 and Nickrl-base superalloy (Inconel 718) was developed. Surlaces of various alloys t,n.ateii by chromizing for the formation ol Cr diffusion layer was subsequently trcaled by plasma nitriding in order t.o form the hard CrS coating layer on the surfaces. This duplex plasma surface tri-atments of chromizing and plasma nitriding have induced a lormation of a duplex-lrcated surfacr hyer of approximat~ls 70-80 $\mu\textrm{m}$thickncss with a iargcly improved microiiardnrss up to approxiniateW 1500Hv(50gf). The main cause for the lage improvment in the surface hardncss is altribilted to [.he fact that CrN and $Fe_xN$ phases are created successfully by ccliromizins and plasma nilriding treatment. High tenipera1,urc wear resislance of the duplex-treated mild steel and HI3 steels at $600^{\circ}C$ was examined. Comparing the duplex-treated specimens with the specimens treated only by chromizing, the rcsults shovmi that, thc wear volume of the duplex-treated mild skcl and 1113 stcel aSt.er a wear test, at $600^{\circ}C$ were reduced hy a Iactor of 8 and 3, respectively. Characteristics of the CrS phase by duplrx treatment were compared with $CrN_x$,/TEX> film by ion plating and the wear behaviors of CrN film lormed by two different nroccsses arc nea.riy identical.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.93-98
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• 2018

This study was wanted to confirm ability for UV blocking according to its material. The lenses materials were Acryl, CR-39, NK-55, and MR-8. It was grouped: Group A consisting of anti-scratch hard coated lenses and anti-refractive multi coated lenses, Group B added UV blocking coating on the group A, and Group C consisting of only UV blocking lenses. The results measured UV transmittance, On the UV-A wavelength, Group A showed the UV transmittance of 7.726%, 0.043%, 0.007%, and 0.007% respectively. Group B showed 0.038%, 0.037%, 0.007%, and 0.007%, respectively. The UV-blocking performance of CR-39 has been greatly improved. Group C has shown the best UV blocking function; only 0.005% and 0.004% of UV transmittances.(1.60 and 1.67 index of refraction respectively). For the low power of lenses and sunglasses, the CR-39 lens is the most used. Therefore, to UV blocking from the lens, new materials or UV absorbers or UV coating technology and development of Converged Technologies are required.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.158-158
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• 2017

Titanium and its alloys have been used in the field dental and orthopedic implants because of their excellent mechanical properties and biocompatibility. Despite these attractive properties, their passive films were somewhat bioinert in nature so that sufficient adhesion of bone cells to implant surface was delayed after surgical treatment. Recently, plasma electrolyte oxidation (PEO) of titanium metal has attracted a great deal of attention is a comparatively convenient and effective technique and good adhesion to substrates and it enhances wear and corrosion resistances and produces thick, hard, and strong oxide coatings. Silicon(Si), Zinc(Zn), and Manganese(Mn) have a beneficial effect on bone. Si in particular has been found to be essential for normal bone and cartilage growth and development. And, Zn has been shown to be responsible for variations in body weight, bone length and bone biomechanical properties. Also, Mn influences regulation of bone remodeling because its low content in body is connected with the rise of the concentration of calcium, phosphates and phosphatase out of cells. The objective of this work was research on bone-like apatite morphology on Si-Zn-Mn-hydroxyapatite coating on Ti-6Al-4V alloy by plasma electrolytic oxidation. Anodized alloys were prepared at 280V voltage in the solution containing Si, Zn, and Mn ions. The surface characteristics of PEO treated Ti-6Al-4V alloy were investigated using XRD, FE-SEM, and EDS.