• Journal of Conservation Science
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• v.26 no.4
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• pp.349-360
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• 2010

The Yeongsheon Sinwoldong three-storied stone pagoda (Treasure No. 465) composed mainly of drusy alkali-granite. The major rock-forming minerals are biotite, quartz, amphiboles, orthoclase and plagioclase. Yellowish brown and black discoloration are formed at the eight sculpture Buddha of the stylobate. A broken rock fragments in the roof material were repaired using epoxy resin and cement mortar in the past. As a result of the infrared thermography analysis from the pagoda, cracks and exfoliation were not serious. Also, P-XRF analysis showed that concentration of Fe (mean 5,599ppm) and S (mean 3,270ppm) were so high in yellowish discoloration parts. Black discoloration area was detected highly Mn (mean 2,155ppm) concentration around the eight sculpture Buddha of the stylobate. The main reason for these are inorganic contaminants from disengaged rock ingredient and organic contaminants from withered plant body. Degree of physical weathering is relatively high in the southern and northern side. The eastern and western side had similar with weathering condition. The northern and eastern side were serious discoloration and biological weathering relatively. Therefore, we suggest that the pagoda need to do cleaning of biological contaminant and conservation treatment to weakened materials of rock and long term monitoring.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.161-166
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• 2000

Classified handmade Korean paper which has been commonly used as the material for the paper cultural assets divide into four classes. We irradiated xenon arc lamp, which has almost the same spectrum distribution as natural sunlight, to test photo-induced of discoloration according to PEG molecular weight and concentration. So, we reach the followings. 1) Unbleached handmade Korean paper with PEG showed rapid decrease of brightness for 10 hours after photo-irradiation, regardless of molecular weight of PEG, but, after 10 hours, it showed gradual increase of brightness. From this, it proved that there was an effect of preventing discoloration of photo-irradiation. 2) Chemical bleached handmade Korean paper showed increase of brightness after 20 hours. Though time was delayed in increase of brightness, there was also an effect of preventing discoloration of photo-irradiation in chemical bleached paper. 3) Handmade Korean paper made with abet-mosk showed the lowest of brightness when it was tested on 400-20% PEG. Before photo-irradiation, the brightness of paper, applied it, was the lowest, but it showed the least difference of brightness after photo-irradiation. From this, it proved that there was the greatest effect of preventing discoloration in this paper. 4) Preventing yellowish, the first phenomena by photo-irradiation ageing with applying PEG was proved that there was the decrease of value of $b^*$ +, and increase value of $L^*$, which could fairly prevent decrease of brightness.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.191-198
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• 2010

This research was performed to investigate the effect of hydrogen peroxide on the stain removal in japanese hackberry. Response surface method (RSM) was used to optimize the bleaching conditions such as reaction temperature, reaction time and the concentration of hydrogen peroxide. Fifteen different bleaching conditions were selected according to $2^3$ factorial central composite design (CCD). The bleaching effect were evaluated by lightness differences of wood surface before and after the bleaching. The RSM model was determined and its $R^2$ values were 0.93, showing it well represented the bleaching effect. The most affecting factor on the stain removal was the concentration of hydrogen peroxide, followed by reaction time and reaction temperature. Second degree of concentration was proved to have an effect on the bleaching. Bleaching rates above 3% concentrations of hydrogen peroxide were tended to be slightly decreased, and low bleaching effect was found at $20^{\circ}C$. The determined RSM model may offer very practical ways to obtain the desired levels of bleaching because it offers multiple solutions.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.165.2-165.2
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• 2016

현재, 솔더범프용 주석계 도금액의 필수성분인 산화방지제의 경우, 국내외 경쟁사에서는 가격 및 성능이 우수한 벤젠/페놀 계열을 적용 중이다. 그러나, 최근 대형 고객사에서 페놀류 산화방지지제를 환경규제물질로 규정함에 따라, 자사에서는, 특허 이슈 해소 가능한 친환경 대체 산화방지제 개발을 해오고 있다. 본 연구에서는, 반도체 패키지용 주석계 도금액의 산화방지제 종류와 농도에 따른 주요 특성 (Particle, 전류 효율, 안정성 (변색, 침전 외), 범프 두께의 편차, 감광제의 침해, Reflow 후 빈공간 등)에 대하여 살펴보았다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.46-46
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• 2014

알칼리 수전해는 신재생에너지를 이용하여 오염물질 없이 효율적으로 수소를 생산할 수 있는 방법 중의 하나이다. 알칼리 수전해 시스템의 산화전극으로 불용성전극이 많이 사용되고 있으나 높은 과전압과 제조 공정이 복잡한 문제점을 가지고 있다. 본 연구에서는 전기변색을 이용해 짙은 파란색의 $TiO_2$ 나노튜브를 알칼리 수전해 시스템의 산화전극으로 이용하고자 하였다. 양극산화법을 이용해 $TiO_2$ 나노튜브를 만드는 과정에서 양극산화 시간과 인가전압에 따라 Blue $TiO_2$의 산소발생반응(Oxygen evolution reaction, OER) 활성 변화를 측정하였고 나노튜브 길이가 길고 직경이 클수록 OER활성과 내구성이 향상되는 것을 확인하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.83-83
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• 2014

선박건조에 사용되는 도료 중 SPC(self-polishing copolymer) A/F(anti-fouling) 도료의 주된 기능은 해양생물의 부착 등 해양생물에 의한 오염을 방지하는 방오성능으로 인식되어 왔으나, 최근 방오성능 뿐 아니라 선박의 운항 시 선체저항을 줄임으로써 발생되는 연료절감효과와 선박의 미관을 위한 변색지연 등 SPC A/F 도료의 다른 기능에 많은 관심을 가지게 되었다. 이러한 관심과 사용자의 요구에 따라 도료사에서는 항력의 감소를 가져 올 수 있는 Silyl acrylate copolymer로 디자인 된 Silyl acrylate SPC A/F 도료를 개발하였으나 SPC A/F 도료의 방오제(biocides) 종류에 따른 방오성능 차이를 비교 평가 할 수 있는 객관적 자료가 부족하여, 본 연구를 통해 SPC A/F 도료의 종류 별 방오성능을 평가하고자 한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.93-93
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• 2008

니켈도금은 각종 소지 상에 직접적이고 밀착성이 양호하고, 변색이 적고 방청력이 크며, 경도, 내식성, 내마모성 및 유연성이 우수하다. 또한 최근 활발히 진행되고 있는 광촉매 연구에 $TiO_2$는 우수한 광화학적 안정성, 효과적인 전하분리, 높은 산화 환원력 및 상업적 적용성을 갖기 때문에 니켈도금용액에 $TiO_2$를 첨가하며 복합도금을 행함으로써 니켈이 가지고 있는 기존의 우수한 특성에 $TiO_2$의 광분해 효과를 부과시킴 으로써 그 특성이 한층 더 향상되는 것을 알수있다. 본 연구에서는 수용액전해질과 비수용액 전해질에서의 Ni-$TiO_2$ 복합도금의 특성을 비교 분석해보았다. 동전위(Potentiodynamic)실험 및 순환전위(Cyclic Voltammetry)실험을 하였으며, 도금층의 특성 및 두께는 OM,SEM을 이용하여 분석하였다. 또한 복합도금 촉매 전극에 의한 광분해 효과를 보기 위해서 UV램프를 이용하여 분석하였다.

• Journal of the Korean Wood Science and Technology
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• v.46 no.3
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• pp.221-230
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• 2018

The purpose of this study was to evaluate the effect of several chemical treatments to prevent photodegradation of wood veneer by external UV (Ultraviolet) light. Of woods, walnut veneer is selected as a raw material for this study since it is known as a luxurious wood with dark color giving an esthetic effect. Alcohol-benzene, hydrogen peroxide ($H_2O_2$) and sodium hypochlorite (NaClO) solution were used for investigate the effect on color stabilization. Despite the removal of the extractive compounds, which is known as a discoloration component, a significant color change of walnut wood veneer was observed. Meanwhile, the veneers treated by 20 and 30% $H_2O_2$ solution at $75^{\circ}C$ for 1 h also showed the no positive effect of color stability exposed to UV light although they have a bleaching effect on wood veneer. Besides, it was difficult to maintain the original color of walnut veneer due to the elution of the extractive compounds. On the other hands, the veneer treated by NaClO solution indicated the good performance on color stability despite of the intensive UV light test. However, when the concentration exceeds 3%, surface roughness and fiber damage occurred simultaneously. Therefore, the walnut species should be treated with proper concentration when sodium hypochlorite is applied to the veneer.

• Journal of Conservation Science
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• v.28 no.3
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• pp.235-245
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• 2012

Nondestructive deterioration diagnosis has been carried out for the former ore dressing plant of the Yongwha mine in Yeongyang (Registered Cultural Property No. 255). Deterioration rates about organic contaminant and soil of the upper part (7 to 13 layer) indicate higher than the lower part (1 to 6 layer) of the ore dressing plants. By contrast, deterioration rates such as crack, break out and discoloration of the lower part indicate very higher than the upper part. It is estimated that the plants of the lower part that mechanical and chemical process had been done for flotation were damaged severely by physicochemical weathering with reaction of concrete and chemical solution. As results of ultrasonic velocity measurement, average p-wave velocity of plants were measured 2,462m/s (compressive strength $529kgf/cm^2$). As for the analytical results of surface contaminants and soil compositions using P-XRF, they were identical with major elements (Cu, Zn, Pb, Fe and As) of ore minerals from the Yongwha mine. Therefore, the ore dressing plant should be treated by phytoremediation with conservation because heavy metals could impinged upon plants and natural environment.

• Journal of the Korean institute of surface engineering
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• v.54 no.1
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• pp.12-17
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• 2021

Among the various precious metals, silver is used in various fields because of its low price than other precious metals. However, the surface of silver remains after rain in the atmosphere containing sulfur ions and chlorine ions, causing silver corrosion and discoloration. Existing documents have developed a anode to prevent corrosion but that are concentrated on secondary batteries. This study tried to prevent corrosion and discoloration of silver by using an Al sacrificial anode. Sulfuric acid decreased the potential of silver and increased the current density at active polarization and OCP. The amount of corrosion of silver with the Al sacrificial anode was reduced from 0.5 % to 6.5%. When silver is used for decoration outside, corrosion and discoloration of silver can be suppressed by installing an Al anode.