• 한국전자통신학회논문지
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• 제6권5호
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• pp.689-696
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• 2011

급식산업은 경제발전상황과 사용자의 편의성 및 고객욕구에 따라 단순급식을 벗어나 고객의 욕구를 만족시킬 수 있는 프리미엄급 급식을 요구하기 시작하였다. 급식 시스템에 도입된 식기에 RFID을 도입 하였으나, 고온과 저온 및 염도에 RFID 칩이 오작동하여 급식시스템에 문제가 발생하였다. 본 논문에서는 IT융합기술이 접목된 스마트 급식을 위하여 Food Court 배식에 RFID 칩을 넣어서 실험을 하였다. Food court 급식 시스템에서 뜨거운 음식($125^{\circ}C$)과 차가운 음식($-40^{\circ}C$) 및 염분이 함유된 음식을 반영하여 고온, 저온 실험, 염수 분무 실험을 통하여 스마트 급식의 안정성을 확보 하였다. 또한 기존의 일자형 배식, 스크램블형 배식, Marketplace 배식, Food Court 배식을 비교 분석하고 장점을 연구하였다. 본 논문연구를 통하여 Food Court 배식에 IT융합 기술인(RFID, LCD, S/W, H/W)을 적용하는 스마트 Food Court 급식산업발전에 기여할 것이다.

• Corrosion Science and Technology
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• 제6권5호
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• pp.257-260
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• 2007

In order to further improve the corrosion resistance and wear resistance of the Ni-P coatings of electroless plating, electroless Ni-P/n-$Al_2O_3$ composite deposits were prepared by adding some nano $Al_2O_3$ Particles in Ni-P plating bath. The bath composition and proproties were studied in this paper. The orthogonal test was applied in order to get the new composite solution, taking the initial stable potential as evaluation standard and considering the elements correlation at the same time. The processing parameters have been optimized by single factor experiment in which the depositing speed was chosen as the evaluation standard. The results showed that the process is stable and the composite Ni-P/n-$Al_2O_3$ deposits werebright and smooth, whose hardness and corrosion resistance are much better than simple Ni-P coatings. Furthermore the surface appearance and structure of the composite Ni-P/n-$Al_2O_3$ coating were investigated by SEM and XRD method. It was proved that the coating surface is typical cystiform cells and its structure is amorphous. All test results ofcomposite coating showed that all various physical coating properties had been improved by adding nano-particles. The hardness of optimal coating is more than 600HV and increases to 1000HV after heat-treating, and its hardness is 20~50% higher than Ni-P coating. The rust points appeared in 200 hour by immersing the coating into the 10%HCl solution and the corrosive speed is $3{\times}10^{-3}mg/(cm^2{\cdot}h)$which was obtained after 300 hour. In the same condition Ni-P coating is $5.6{\times}10^{-3}mg/(cm^2{\cdot}h)$. The salt spray resistance of the layers can exceed 600h with the thickness $20{\mu}m$.

• 한국표면공학회지
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• 제49권2호
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• pp.202-210
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• 2016

This study was intended to investigate the effect of the amount of magnesium addition and heat treatment in the Al-Mg coating film in order to improve corrosion resistance of aluminum coating. Al-Mg alloy films were deposited on cold rolled steel by physical vapor deposition sputtering method. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of $400^{\circ}C$ for 10 min. The morphology was observed by SEM, component and phase of the deposited films were investigated by using GDLS and XRD, respectively. The corrosion behaviors of Al-Mg films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of magnesium content, the morphology of the deposited Al-Mg films changed from columnar to featureless structure and particle size was became fine. The x-ray diffraction data for deposited Al-Mg films showed only pure Al peaks. However, Al-Mg alloy peaks such as $Al_3Mg_2$ and $Al_{12}Mg_{17}$ were formed after heat treatment. All the sputtered Al-Mg films obviously showed good corrosion resistance compared with aluminum and zinc films. And corrosion resistance of Al-Mg film was increased after heat treatment.

• 한국표면공학회지
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• 제50권5호
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• pp.366-372
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• 2017

Plasma electrolytic oxidation(PEO) has attracted attention as a surface treatment which has high wear resistance and corrosion resistance. PEO is generally considered as cost-effective, environmentally friendly and superior in terms of coating performance. Most of studies about the PEO processes have been applied to light metals such as Al and Mg. Because the strength of Al and Mg is weaker than that of steel, there is a limit to the application. In this study, PEO process was used to form oxide coatings on Hot dipped aluminized(HDA) steel and the characteristics of the coating film according to the PEO current density were studied. The morphology was observed by SEM and component was analyzed by using EDS. The corrosion behaviors of PEO coating films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of PEO process current density, the pore size of the coating surface and the thickness of coating increased. It was confirmed that no Fe component was present on the coating surface. PEO coating films obviously showed good corrosion resistance compared with HDA. It is considered that the PEO coating acts as a barrier to protect the base material from external factors causing corrosion.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.32-32
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• 2015

Electrophoretic paint (E-paint) was investigated on four different magnesium substrates: as-extruded AZ61 (AZ61), heat-treated AZ61 (AZ61-H), as-extruded TZ61 (TZ61) and heat-treated TZ61 (TZ61-H), to elucidate the effect of heat treatment and alloying elements on the deposition and corrosion resistance of E-paint. It was found that, a rapid increase of voltage, indicating that the deposition of E-paint had started, was observed after an induction time of 0.39 min for AZ61-H, 0.43 min for AZ61, 0.51 min for TZ61-H and 0.58 min for TZ61. The amount of E-paint deposited on the four samples was approximately similar, but the electrical charge used for the deposition process on the heat-treated samples was smaller than that on the as-extruded samples. The current efficiencies of E-paint on AZ samples (AZ61 and AZ61-H) were higher than those of TZ samples (TZ61 and TZ61-H), and on the heat-treated samples were higher than on as-extruded samples. All E-paintings on the four magnesium substrates had an excellent adhesion without any paint detached by tape peel-test. However, many large blisters were formed on the surface of AZ samples, and none, or very small blisters were observed on TZ samples after immersion test in DI-water for 500 h at $40^{\circ}C$. Under salt spray test (SST) conditions, E-paint on AZ samples showed blistering adjacent to scribes, while blistering of E-paint occurred on intact areas of TZ samples. The E-paint on heat-treated samples showed much better corrosion resistance than that on as-extruded samples. The ranking of greater to lesser corrosion resistance of the E-paint on these four different magnesium substrates is indicated by the order: AZ61-H > AZ61 > TZ61-H > TZ61.

• 한국재료학회지
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• 제16권11호
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• pp.681-686
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• 2006

Plasma nitrocarburising and plasma post oxidation were performed to improve the wear and corrosion resistance of S45C and SCM440 steel by a plasma ion nitriding system. Plasma nitrocarburizing was conducted for 3h at $570^{\circ}C$ in the nitrogen, hydrogen and methane atmosphere to produce the ${\varepsilon}-Fe_{2-3}$(N, C) phase. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of $500^{\circ}C$ for 1 hour. The very thin magnetite ($Fe_3O_4$) layer $1-2{\mu}m$ in thickness on top of the $15{\sim}25{\mu}m$ ${\varepsilon}-Fe_{2-3}$(N, C) compound layer was obtained by plasma post oxidation. A salt spray test and electrochemical testing revealed that in the tested 5% NaCl solution, the corrosion characteristics of the nitrocarburized compound layer could be further improved by the application of the superficial magnetite layer. Throttle valve shafts were treated under optimum plasma processing conditions. Accelerated life time test results, using throttle body assembled with shaft treated by plasma nitrocarburising and post oxidation, showed that plasma nitrocarburizing and plasma post oxidation processes could be a viable technology in the very near future which can replace $Cr^{6+}$ plating.

• 공업화학
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• 제16권2호
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• pp.212-216
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• 2005

아연도금 강판의 부식을 방지하기 위하여, 방청제로서 사용하고 있는 벤조트리아졸을 유기화제로 사용하여 이를 Na-montmorillonite (Na-MMT)에 삽입시켰다. 이것을 XRD로 관찰한 결과 벤조트리아졸의 삽입으로 인하여 MMT의 층간 거리가 증가하였음을 보여주고 있다. 그리고 코팅액으로 사용하기 위하여 벤조트리아졸이 삽입된 MMT를 이용하여 수용성 poly(ethylene-co-acrylic acid) (PEA) 나노복합재료를 제조하였다. 나노복합재료는 PEA 매트릭스에 실리케이트가 단일층으로 잘분산되어 있는 박리형 나노복합재료임을 보여주고 있다. 이것을 인용하여 아연도금강판에 코팅하여 염소분무 시험한 결과 금속의 내식성을 현저히 증가시켰다. 이러한 결과는 PEA 매트릭스에 균일하게 분산되어 있는 실리케이트 층에 의한 산소투과도 감소와 방청제의 효과에 의한 것이다.

• 한국산학기술학회논문지
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• 제15권5호
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• pp.3251-3259
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• 2014

본 논문에서는 철근의 부식을 고려한 철근콘크리트(RC)보의 휨파괴거동을 규명하기 위하여 수행한 일련의 3점휨 파괴시험 및 해석적 연구 결과를 제시하였다. 실험적 연구를 위하여 총12개의 시편보를 제작하였으며, 염수분무시험 챔버를 이용하여 10개월간 촉진부식토록 하였다. 철근부식에 미치는 균열의 영향을 분석하기 위하여 일부 시험체를 공칭휨강도의 30% 와 60%에 해당하는 최대하중으로 미리 하중을 가한 후 염소분무 시험챔버에 보관하였다. 재령 5개월 및 10월에 각각 휨파괴시험을 실시하였으며 최대하중과 하중-처짐곡선을 측정하였다. 실험결과 철근의 부식정도에 따라 철근과 콘크리트간의 부착력 손실이 발생하고 그에 기인하여 휨강도는 최대 5.4%, 연성도는 최대 43%의 저하가 발생하여 철근의 부식이 최대 하중 보다 연성도에 미치는 영향이 큰 것으로 나타났다. 한편, Maaddawy의 해석적 모델을 이용한 수치해석결과 철근의 부식을 고려한 RC보의 휨파괴거동을 상당부분 잘 묘사할 수 있는 것으로 나타났다.

• 한국표면공학회지
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• 제45권3호
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• pp.111-116
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• 2012

Oblique angle deposition (OAD) is a physical vapor deposition method which utilizes non-normal angles between the substrate and the vaporizing source. It has been known that tilting the substrate changes the properties of the film deposited on it, which was thought to be a result of morphological change of the film. In this study, OAD has been applied to prepare single and multilayer Al films by magnetron sputtering. The magnetron sputtering source of 4 inch diameter was used to deposit the films. Al films have been deposited on Si wafers and cold-rolled steel sheets. The multilayer films were prepared by changing the tilting angle upside down at each layer interval, which means that when the first layer was deposited at an angle of $+45^{\circ}$, the second layer was deposited at an angle of $-45^{\circ}$, and vice versa. The microstructure, surface roughness and reflectance of the films were investigated using a scanning electron microscope, a surface profiler and a spectrophotometer, respectively. The corrosion resistance was measured and compared using the salt spray test. The single layer film prepared at an oblique angle of $60^{\circ}$ prepared at other angles. However, for the multilayer films, the film prepared at an oblique angle of $45^{\circ}$ showed the most compact and featureless structure. The multilayer films were found to exhibit higher corrosion resistance than the single layer films.

• 한국표면공학회지
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• 제51권4호
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• pp.224-230
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• 2018

In this study, Mg films were prepared on hot dip aluminized steel (HDA) by using a sputtering method as a high corrosion resistance coating. The corrosion resistance of the Mg films was improved by controlling the morphology and the crystal structure of films by adjusting the Ar gas pressure during the coating process. Anodic polarization measurement results confirm that the corrosion resistance of the Mg films was affected by surface morphology and crystal structure. The corrosion resistance of the Mg coated HDA specimen increased with decreasing crystal size of the Mg coating and it was also improved by forming a film with denser morphology. The crystal structure oriented at Mg(101) plane showed the best corrosion resistance among crystal planes of the Mg metals, which is attributed to its relatively low surface energy. Neutral salt spray test confirmed that corrosion resistance of HDA can be greatly improved by Mg coating, which is superior to that of HDG (hot dip galvanized steel). The reason for the improvement of the corrosion resistance of Mg films on hot dip aluminized steel was due to the barrier effect by the Mg corrosion products formed by the corrosion of the Mg coating layer.