• Journal of Conservation Science
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• v.26 no.4
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• pp.437-443
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• 2010

The influence of noxious corrosive gas, which is the product of fossil fuel, and the acidic descent material, which becomes the reason for such reaction, on wax which protects the cultural assets, and the habitat factor were researched. It could be viewed that corrosion occurred rapidly due to the acidic descent material, which have the long staying on the material, rather than harmful corrosive gas. Also, it could be figured out that such corrosion began from whitening phenomenon of coated wax. As the acidity increased, more whitening phenomenon occurred, and eventually, it could be found out that whitening effect began due to the acidic descent material, corrosive gas and various 0.1 M acid solution, which lead to the exposure of internal metal, and corrosion occurred. The wax with the greatest resistance to the acidity due to its least changing aspect seemed to be Renaissance wax, except sulfuric acid.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.650-658
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• 2010

We used green manure crops such as hairy vetch, crimson clover, rye, sorghum, and sudan grass by mixing with soils to assess the effects of green manure crops on nutrient supply and soil quality improvement. Temporal changes in soil inorganic nitrogen, carbohydrate, microbial biomass, and humus content were determined as soil quality indicators. Inorganic nitrogen content of the control maintained similar level during the whole period, but it had continually increased until 4 weeks after incorporation (WAI) of green manure crops. Especially, inorganic nitrogen content sharply increased in sudan grass. After incorporation of green manure crops, temporal change of soluble sugar in soils was as follows: it had gradually increased in legume green manure crops-incorporated soils until 7 WAI, which was the highest, and then showed the tendency to be reduced. Meanwhile, it in non-legume green manure crops-incorporated soils rapidly increased after the incorporation, and reached the maximum around 4 WAI. Humic acid by the decomposition of crop residues in green manure crops-incorporated soils was greatly enhanced with the elapsed time of 4 WAI, although it was low at the same level as the control until 2 weeks. In addition, there was a difference in fulvic acid by incorporated crops, fulvic acid in hairy vetch, sorghum and sudan grass showed a similar tendency with the change in humic acid. Our results suggest that soluble sugar, microbial activity and humic acid could be available indicators to evaluate the fertility of green manure crops-incorporated soils.

• Analytical Science and Technology
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• v.14 no.1
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• pp.80-87
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• 2001

This research was studied the action of the coupling ozone-hydrogen peroxide on aqueous humic acid. PEROXONE process is enhanced the generation of hydroxyl radicals which is effective for degradation of organic matters. Therefore the changes of $UV_{254}$ and TOC were investigated through the change of concentrations, injection time of $H_2O_2$, initial pH of aqueous humic acid and concentrations of radical savenger as $HCO_3{^-}$ in the PEROXONE processes. And the GC/ECD was used to detect the formaldehyde formed by ozonation of humic acid. From the experimental results, concentrations and injection time of $H_2O_2$ and initial pH in solution in the PEROXONE processes were very important for enhancing the efficiency of degradation in humic acid. The results indicated that removal efficiency of TOC was the highest when concentration of $H_2O_2$ was 5mg/L, injection time of $H_2O_2$ was 5 minutes and initial pH in solution was 10.5. And presence of alkalinity in solution was reduced the efficiency of treatment. The formaldehyde were formed less PEROXONE processes than only ozone. When initial pH in solution were changed from 3.5 to 10.5, the formaldehyde were formed highest concentration at pH 5.

• Korean Journal of Environmental Agriculture
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• v.12 no.2
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• pp.162-168
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• 1993

This research was conducted to assess the influence of humic or fulvic acid on Bentazone phytotoxicity using a bioassay with hydroponically grown cabbage (Brassica campestris subsp. napus var. pekinensis Makino). Concentrations of Bentazone in the water culture media were ranged from 0 to 32 ${\mu}M $ and those of the organic ligands were 1.0mM as a soluble carbon. Media were prepared in a complete factorial combination with pHs of 4.5, 6.5 and 8.5. The phytotoxicity indices on growth rate and dry weight decrement were employed to evaluate the effects of organic ligands on the Bentazone phytotoxicity. Humic or fulvic acid without Bentazone treatment enhanced the growth of cabbage and this effect was evident at low pH of 4.5. Bentazone led to chlorosis and necrosis on cabbage leaves resulting in the decreases of dry and fresh weights and growth rate. This phytotoxic effect was increased with Bentazone concentration and evident at low pH. At pH 4.5, dry weight was decreased about 63% with 8${\mu}$M of Bentazone treatment. Effective concentration of Bentazone causing 50% decreases in fresh weight as compared to the control was estimated to be 21${\mu}$M. Presence of organic ligand reduced the phytotoxicity of Bentazone to cabbage significantly by increasing yields and growth rates as compared to the treatment of Bentazone alone. At pH 4.5, fulvic acid reduced phytotoxicity of Bentazone upto 46%, and this efficiency of fulvic acid was better than that of humic acid under the same condition.

• Weed & Turfgrass Science
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• v.7 no.1
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• pp.62-71
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• 2018

This study was conducted to evaluate the effect of liquid fertilizer containing humate (LFH) on changes of turfgrass quality and growth by investigating visual quality, chlorophyll content, dry weight of clipping, and nutrient content in leaves tissue. Treatments were designed as follows; control fertilizer (CF), HF-1 ($CF+1.0mL\;m^{-2}\;LFH$), HF-2 ($CF+2.0mL\;m^{-2}\;LFH$), and HF-3 ($CF+4.0mL\;m^{-2}\;LFH$). As compared with CF, soil chemical properties of LFH treatments were not significantly. Visual quality and root dry weight of LFH treatments were higher than that of CF. Chlorophyll content, clipping yield and nitrogen uptake of HF-2 and HF-3 were increased 11.2-11.8%, 15.3-30.0%, 22-42% by application of LFH. The LFH level was positively correlated with visual quality, chlorophyll content, clipping yield or nutrient uptake amount. These results indicated that the application of LFH improved the growth and quality of creeping bentgrass by increasing nutrient uptake and by prompting root growth.

• Weed & Turfgrass Science
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• v.7 no.3
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• pp.259-268
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• 2018

This study was conducted to evaluate the effect of liquid fertilizer containing humic acid and Saccharomyces cerevisiae broth (LHS) on changes of turfgrass growth by investigating visual quality, chlorophyll content, dry weight of clipping, and nutrient content in leaf tissues. Treatments were designed as follows; control fertilizer (CF), HS-1 ($CF+1.0mL\;m^{-2}\;LHS$), HS-2 ($CF+2.0mL\;m^{-2}\;LHS$), and HS-3 ($CF+4.0mL\;m^{-2}\;LHS$). After treatment of LHS on creeping bentgrass, soil pH in the treated plots was decreased than that of CF. As compared to CF, visual quality, chlorophyll content and content of N, P and K were not significantly different in the LHS treatments. However, clipping yield and phosphorus uptake of HS-2 were significantly increased by 22% and 33%, respectively. These results showed that application of LHS improved the phosphorus uptake and growth of creeping bentgrass, which would be an alternative management tool for the cool season turfgrass under stress conditions.

• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.19-28
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• 2021

Corrosion is the degradation of metals by reaction with the environment. It is difficult to completely remove. Corrosion proceeds rapidly after the protective barrier is destroyed, and several reactions occur that alter the composition and properties of the metal surface and local environments, such as diffusion of metal cations into the matrix, the formation of oxides, and local pH changes. The study of corrosion of steel and iron is of theoretical and practical interest and is receiving considerable attention. Acid solutions, which are widely used in industrial pickling, acid descaling, cleaning and acidification of oil wells, require the use of corrosion inhibitors to suppress corrosion attacks on metallic materials. Physical removal of rust requires expensive special equipment, and chemical removal of it can cause corrosion or shorten the life of the metal. In this study, an eco-friendly rust cleaner was developed using cosmetics and food materials by applying the concept of perm reducing agent and chelate, and applied to remove rust from industrial and hot water pipes and various industrial devices. As a result, it was found that rust cleaners remove rust more effectively and safely compared to conventional treatment methods. At the same time, the rust removal efficiency was 1.75 to 2.5 times better for industrial piping and 1.56 to 2.2 times better for boiler hot water than conventional methods.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.6-6
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• 2018

본 연구에서는 고문헌에 기록된 도금 재료와 도금법 등을 확인하고 이를 기초자료로 활용하여 매실산을 사용한 금(Au)-수은(Hg) 아말감기법으로 고대 도금(鍍金)기술을 되살리고, 이를 토대로 경주 월지에서 출토된 금동삼존판불을 복원하였다. 먼저, 전통 도금법을 되살리기 위해서, "오주서종박물고변", "확지신편", 조선시대 각종 의궤 등에 공통적으로 기록되어 있는 매실에 주목하고, 매실을 3~4개월 발효 숙성 후 착즙한 뒤 그것을 농축하여 만든 매실산을 도금 실험에 적용하였다. 금아말감 도금을 위하여 월지 출토 금동삼존판불의 바탕소지금속인 청동삼존판불을 구리와 주석 89:11(Cu:6kg, Su:750g)로 합금하여 주물사 주조법으로 복원하였으며, 동일한 합금비로 제작된 $2.3cm{\times}3.5cm$(가로${\times}$세로)의 시편에 사전 실험을 실시하였다. 현대적 산처리 방식에 사용되는 질산과 전통방식으로 사용되는 매실산으로 시편에 산처리 한 후 각각 비교해 보고, 금분과 금박, 상온과 가온에 따른 아말감상태를 비교하는 실험을 진행하였는데, 실험에 사용된 매실산 70%는 pH가 1.94로, 오늘날 산처리에 사용하고 있는 질산 20%와는 차이가 있지만, 청동 시편 실험을 통해 매실산에 20분 정도 담근 뒤 금아말감을 도포 후 24시간 지나 가열($380{\sim}400^{\circ}C$) 했을 때 금도금이 잘 되어, 현대적 방법인 질산처리로 도금을 한 시편과 큰 차이가 없는 것으로 관찰되었다. 사전 실험을 통한 결과를 적용한 월지 출토 금동삼존판불 복원은 청동삼존판불 표면처리, 금-수은 합금 및 도금하기, 도금 후 표면처리의 순서로 진행되었는데, 금과 소지금속의 밀착력을 높이기 위해 표면을 숯을 이용해 탈지한 후 물로 씻어내고 매실산을 도포하여 20분 동안 두어 부식 및 세척을 시행하였다. 금도금을 위한 금-수은아말감은 가온할 때 수은이 증발하는 양을 고려하여 금1 : 수은10 비율로 합금하여 완성하였으며, 금아말감 도포 후 약 24시간 지난 다음, $380{\sim}400^{\circ}C$에 가열하여 수은을 기화시켜 도금작업을 완성하였다. 금아말감도금은 평균적으로 6~7차례 시행하여야 완벽히 도금되지만, 본 연구에서는 단 4차례의 도금만으로 금아말감도금을 완성시켰는데, 이것은 금아말감을 바탕소지인 청동에 도포한 후 24시간 동안 금아말감과 청동과의 반응 시간을 두게한 것이 큰 역할을 한 것으로 보이며, 이는 청동시편을 이용한 실험과 과학적 분석을 통하여 입증하였다. SEM으로 표면을 관찰한 결과 아말감 도포시간이 즉시인 경우 도금이 거의 되지 않은 것을 확인할 수 있었고 36시간이 넘어갈 경우 금 도금층이 불균일하게 관찰되었으므로 도금시간은 12시간~24시간 이내가 적절함을 확인할 수 있었다. EDS로 성분을 분석한 결과 산처리 시간이 20분인 시료의 경우 5 wt% 내외로 수은의 비율이 다른 시료에 비해 낮은 것을 확인할 수 있었다. 실험 및 분석결과 산처리 시간이 20분이고 아말감 도포시간이 24시간일 때 도금이 잘 이루어지므로 이 결과를 토대로 금동삼존판불을 복원하였다. 이번 연구를 통해 도금법에 표면을 세척하고 부식시키기 위해 사용한 물질이 매실산임을 찾아내어 확인할 수 있었는데, 이러한 점 에서 이 연구의 가장 큰 의미는 전통 소재와 기술을 복원한 것으로, 앞으로 매실산을 이용한 금 도금기술은 관련 학계에도 큰 기여를 할 것으로 기대된다.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.237-243
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• 2008

Chemical and microbial characteristics of bacterial populations were investigated in a quercus and pine humus forest soil. Soil pH was $5.3\pm0.4$ and $4.1\pm0.9$ from each sample of a quercus and pine humus forest soil; C/N ratio of humus forest soil was $17.84\pm4.6%$ and $21.76\pm8%$, respectively. Total organic acid was investigated as 69.57 mM/g dry soil and 53.72 mM/g dry soil in each humus forest soil. Glutamine, pyruvate, succinate, lactic acid and acetic acid of pine humus forest soil were $1.5\sim4.5$ times higher than those of quercus humus forest soil. As we evaluated phylogenetic characteristics of bacterial populations by 16S rRNA-ARDRA analysis with DNA extracted from each humus forest soil. Based on the 16S rRNA sequences, 44 clone from ARDRA groups of quercus humus forest soil were classified into 7 phyla: ${\alpha},{\beta},{\gamma},{\delta}$-Proteobacteria, Acidobacteria, Actinobacteria, and Firmicutes. Thirty-two clone from ARDRA groups of pine humus forest soil were classified into 8 phyla: ${\alpha},{\beta},{\gamma}$-Proteobacteria, Acidobacteria, Bacteroides, Verrucomicrobia, Planctomycetes, and Gemmatomonadetes. According to PCA (Principal Component Analysis) based on 16S rRNA base sequence, there were three main groups of bacteria. All clone of Cluster I were originated from quercus humus forest soil, while 67% clone of Cluster II and 63% clone of Clusters III were separated from pine humus forest soil.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.526-536
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• 2008

The purpose of this study was to compare the effect of various dentin bonding systems on microtensile bond strength of immediate dentin sealing (IDS) and delayed dentin sealing (DDS). Eighteen extracted permanent molars were used in this study. The teeth for DDS group were restored with a provisional restorations, and immersed in saline solution for 1 week, and divided into 3 subgroups according to various dentin bonding adhesives; SB subgroup (3 step total-etch adhesive), SE subgroup (2 step self-etch adhesive), XE subgroup (1 step self-etch adhesive). In IDS group, the teeth were divided into 3 subgroups, and applied with bonding adhesives as in DDS group. The teeth were restored with provisional restorations, and immersed in saline solution for 1 week. Indirect composite disc was cemented with resin cement, and all specimens were subjected to microtensile bond strength. The data were statistically analyzed with oneway ANOVA and Student t-test. The results were as follows: 1. The IDS group showed significantly higher ${\mu}TBS$ than DDS group in 3 step total-etch and 2 step selfetch adhesive (p < 0.05). 2. In IDS and DDS group, 3 step total-etch adhesive showed the highest ${\mu}TBS$ value, followed by 2 step self-etch, and 1 step self-etch adhesive. In IDS group, the ${\mu}TBS$ value for 1 step self-etch adhesive was significantly different from those of the other subgroups (p < 0.05), and in DDS group, there were statistical differences in all subgroup (p < 0.05). 3. Failure modes of tested dentin bonding adhesives were mostly mixed failure and only 1 step self-etch adhesive showed adhesive failure.