• 청정기술
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• 제16권3호
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• pp.162-171
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• 2010

본 연구에서는 유기산, 무기산, 여러 첨가제들을 이용하여 옥내급수관의 스케일 제거에 적합한 환경친화적인 세정제를 개발하고자 연구를 수행하였다. 여러 유기산 중에서 oxalic acid, citric acid, malic acid 등의 경우 산화철 제거에 비교적 좋은 효율을 보였다. 이들 유기산들을 주축으로 하여 보조제를 첨가하여 옥내급수관 스케일의 주성분인 산화철 제거 평가실험을 하였다. 여러 첨가제 중에 비이온 계면활성제가 산화철 제거력 향상에 매우 뛰어남을 확인할 수 있었다. 그리고 산화철에 대해 높은 용해력을 보인 두 종류의 배합세정제 $F_1$과 $F_2$를 제조하였는데 배합세정제 $F_1$의 경우 유기산과 첨가제로만 이루어져 있어 기존의 화학세척제에 비하여 안전하고 환경친화적이지만 비교적 산화철 용해력이 조금 떨어졌고, $F_2$의 경우는 $F_1$에 무기산을 소량 첨가함으로 산화철 용해력을 보완해 줌으로써 보다 높은 산화철 세정력을 필요로 할 때 사용하는 것이 좋을 것으로 판단된다. 따라서 옥내급수관 세정 시 스케일의 정도에 따라 배합후보 세정제를 선택하는 것이 바람직하다고 판단된다.

• Clinical and Experimental Pediatrics
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• 제57권5호
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• pp.211-216
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• 2014

Asthma comprises a heterogeneous group of disorders characterized by airway inflammation, airway obstruction, and airway hyperresponsiveness (AHR). Airway inflammation, which induces AHR and recurrence of asthma, is the main pathophysiology of asthma. The fractional exhaled nitric oxide (FeNO) level is a noninvasive, reproducible measurement of eosinophilic airway inflammation that is easy to perform in young children. As airway inflammation precedes asthma attacks and airway obstruction, elevated FeNO levels may be useful as predictive markers for risk of recurrence of asthma. This review discusses FeNO measurements among early-childhood wheezing phenotypes that have been identified in large-scale longitudinal studies. These wheezing phenotypes are classified into three to six categories based on the onset and persistence of wheezing from birth to later childhood. Each phenotype has characteristic findings for atopic sensitization, lung function, AHR, or FeNO. For example, in one birth cohort study, children with asthma and persistent wheezing at 7 years had higher FeNO levels at 4 years compared to children without wheezing, which suggested that FeNO could be a predictive marker for later development of asthma. Preschool-aged children with recurrent wheezing and stringent asthma predictive indices also had higher FeNO levels in the first 4 years of life compared to children with wheezing and loose indices or children with no wheeze, suggesting that FeNO measurements may provide an additional parameter for predicting persistent wheezing in preschool children. Additional large-scale longitudinal studies are required to establish cutoff levels for FeNO as a risk factor for persistent asthma.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.211-211
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• 2011

Nanostructures, with a diversity of shapes, built on substrates have been developed within many research areas. Lithography is one powerful, but complex, technique to make structures at the nanometer scale, such as platinum nanowires for studying CO catalytic reactions [1], or aluminum nanodisks for studying the plasmon effect [2]. In this work, we approach a facile method to construct nanostructures using noble metals on a titania thin film by using self-assembled structures as a pattern. Here, a large-scale silica monolayer is transferred to the titania thin film substrates using a Langmuir-Blodgett trough, followed by the deposition of a thin transition metal layer. Owing to the hexagonal close-packed structure of the silica monolayer, we would obtain a metal nanostructure that includes separated metallic triangles (islands) after removing the patterning silica beads. This nanostructure can be employed to investigate the role of metal-oxide interfaces in CO catalytic reactions by changing the patterning silica particles with different sizes or by replacing the oxide support. The morphology and chemical composition of the structure can be characterized by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. In addition, we modify these islands to a connected island structure by reducing the silica size of the patterning monolayer, which is utilized to generating hot electron flow based on the localized surface plasmon resonance effect of the metal nanostructures.

• 한국표면공학회지
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• 제33권1호
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• pp.3-9
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• 2000

Arc-melted alloys of TiAl-(o.25, 0.5, 1.0at%) Si were isothermally oxidized at 800, 900 and $1000^{\circ}C$ in air for 60hr. It was found that the oxidation resistance of the prepared TiAl-Si alloys was much better than that of pure TiAl, being progressively increasing with an increase in the Si content. This was attributed to the formation of $SiO_2$in addition to ($TiO_2$+$Al_2$$O_3$) oxides which formed in TiAl alloys with and without silicon additions. However, the silica formation within the oxide layer unfortunately accelerated the oxide scale spallations. During oxidation, all the elements in the base alloy diffused outward, whereas oxygen from the atmosphere diffused inward. The oxides were primarily composed of an outer thick $TiO_2$layer, an intermediate diffuse $Al_2$$O_3$layer and an inner $TiO_2$layer. A small amount of $SiO_2$was present all over the oxide scale and some voids were found around the intermediate layer.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.131-132
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• 2015

$Ti_{0.26}Al_{0.16}Si_{0.01}N_{0.57}$ (at%) coatings were synthesized on stainless steel 304 by using arc ion plating systems (AIPS). Targets employed for the deposition were Ti, AlSi(67:33at%) and AlSi(82:18at%). The thickness of TiAlSiN coatings is $4{\mu}m$. The oxidation characteristics of the deposited coatings were studied by thermogravimetric analysis (TGA) in air between 800 and $900^{\circ}C$ for 75 hr. The oxide scale formed on the TiAlSiN coatings consisted of $rutile-TiO_2$ layer and ${\alpha}-Al_2O_3$. At $800^{\circ}C$, the coatings oxidized relatively slowly, and the scales were thin and adherent. When oxidized above $900^{\circ}C$, $TiO_2$ grew fast over the mixed oxide layer, and the oxide scale formed on TiAlSiN coatings was prone to spallation. Microstructural changes of the TiAlSiN coatings that occurred during high temperature oxidation were investigated by EPMA, XRD, SEM and TEM.

• 열처리공학회지
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• 제14권5호
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• pp.282-285
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• 2001

Based on the mass balance of anion and cation fluxes, the parabolic rate constant ($K_p$) of oxide grown during the high-temperature oxidation of metal is theoretically calculated. It is assumed that the diffusion of oxygen anion and metal cation through oxide scale obeys the Fick's 1st law, the growth of oxide is controlled by the diffusion of ions, electrical potential gradient as driving force for diffusion of ions is ignored, and oxidation occurs within an existing oxide layer. Then, the parabolic rate constant can be expressed by $K_p=[2{\rho}_{MmOn}{M^2}_{MmOn}(mD_oC_o{^e}+nD_MC_M{^e})/nm]$.

• 한국재료학회지
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• 제14권4호
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• pp.281-286
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• 2004

The oxide scales formed on Ni-18W(at.%) coating that was electrodeposited on steel were investigated using XRD, SEM and TEM. The oxide scales consisted mainly of an outer NiO layer, and an inner thick ($NiWO_4$+NiO) mixed layer. The unoxidized coating below the oxide scale was rich in Ni and depleted in W, owing to the consumption of Wand the resultant Ni enrichment. The oxidation resistance of Ni-18W coating was poorer than that of the TiN coating, due to the formation of nonprotective NiWO$_4$. During oxidation, Ni and the substrate element of Fe diffused outward, while oxygen inward, according to the concentration gradients.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.150-151
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• 2013

Recently, the internal space organization of the building changes to the frame construction and flat slab construction in the wall type structure. And the use of light weight panel changing the internal joint use easily is increased. Therefore, in this research, the length change characteristic that the magnesium chloride addition rate reaches to the magnesium curing body tries to be studied. It could confirm according to the length change specific result that the magnesium chloride amount of addition reaches to the magnesium oxide curing body to expand. And the thing described below was the large-scale expansion the magnesium oxide addition rate 60%. And it showed up as 50, 40, 30, 20, and order of 10s (%). It could look at to form the hydrate of the SEM picture result needle-shaped of the Hardened.

• Corrosion Science and Technology
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• 제14권3호
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• pp.127-131
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• 2015

Model alloys Fe-9Cr, Fe-20Cr and Fe-20Cr-20Ni (wt. %) with 0.1 and 0.2 % Si were exposed to $Ar-20CO_2-20H_2O$ gas at $818^{\circ}C$. The undoped alloys formed a thick iron-rich oxide scale. The additions of Si reduced scaling rates of Fe-9Cr to some extent but significantly suppressed the formation of iron oxide scales on Fe-20Cr and Fe-20Cr-20Ni. Carburisation also occurred in all undoped alloys, but not in Si-containing Fe-20Cr and Fe-20Cr-20Ni. Protection against carburisation was a result of the formation of an inner scale layer of silica.

• 한국재료학회지
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• 제14권7호
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• pp.457-461
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• 2004

The thermomechanically treated $Ti-45.4\%Al-4.8\%Nb(at\%)$ alloy was oxidized between 800 and $1000^{\circ}C$ in air, and the oxidation characteristics were studied. The dissolution of Nb in the oxide scale was observed from the TEM study. The Pt marker test revealed that the oxidation process was controlled by the outward diffusion of Ti ions and the inward diffusion of oxygen ions. During oxidation, the evaporation of Nb-oxides was found to occur to a small amount. Niobium tended to pile-up at the lower part of the oxide scale, which consisted primarily of an outer $TiO_2$ layer, and an intermediate $Al_{2}O_{3}-rich$ layer, and an inner mixed layer of ($TiO_{2}+Al_{2}O_{3}$).