• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.43-44
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• 2022

In this study, the optimum amount of chloride ions is used to collaborate with hybrid corrosion inhibitor for carbon steel rebar treatment in simulated pore concrete (SCP) solution is discovered. The corrosion inhibition performance of hybrid inhibitors is carried on by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP). The highest corrosion inhibition resistance is found in case of LP-C2 after 240 h exposure. Surface studies including scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to figure out the surface morphology of the steel rebar treated with hybrid inhibitors in order to collaborate well with electrochemical studies. Anodic type inhibition action was confirmed by potentiodynamic polarization study.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.409-411
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• 2017

미사일 추력기 체계에 적용되는 하이드라진[$N_2H_4$]추진제는 MSDS-OHS 유해성 분류상 급성독성 물질로서 사용이 제한되고 있는 바, 다양한 대체물질이 개발 중이다. 최근 해외에서 안전성과 취급이 우수한 질산 히드록실암모늄[$NH_3OHNO_3$]과 암모늄 디나이트라마이드[$NH_4N(NO_2)_2$] 기반 단일계 액상추진제가 개발중이며, 이 물질들을 이용한 추력기 시스템 적용 시험이 진행되고 있다. 그러나 저온에서의 연로물질 산성화 반응으로 인한 디나이트라마이드[$N(NO_2)_2{^-}$] 물질의 분해는 나이트레이트[$NO_3{^-}$] 이온 생성을 촉진시키며, 부수적으로 발생하는 침전물은 촉매 및 노즐의 막힘 현상을 유발하므로 추력기 성능의 저해요인으로 작용한다. 그러므로 저온분해 방지를 위한 첨가제 조성 개발 및 열분해 특성 연구가 최근의 관심사이다. 본 연구는 합성/정제/추출한 암모늄 디나이트라마이드 산화제를 주요 조성물로 적용하였으며, 염기성 안정화제를 질량비율 4~5% 첨가하여 산성화 반응을 억제시킨 단일계 액상추진제(KMP) 형태로 제조하였다. 합성한 추진제는 시차주사열량계(DSC)를 이용하여 분해온도를 측정하여 열안정성을 평가해보았다.

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.46-51
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• 2015

BACKGROUND: This study aimed at investigating the effects of sulfur-containing compounds widely used as environment-friendly organic fungicides against ginseng anthracnose, and determining the appropriate application concentration for lowering chemical injury to ginseng leaves. Ginseng anthracnose, caused by Colletotrichum gloeosporioides, is a destructive disease that significantly reduces the yield of ginseng. METHODS AND RESULTS: Ginseng anthracnose, caused by Colletotrichum gloeosporioides, is a destructive disease that significantly reduces the yield of ginseng. In a 2-year-old ginseng grown in a pot, treatment with loess-sulfur complex containing 0.06% sulfur and fermented loess-sulfur complex containing 0.13% sulfur did not show any chemical injuries. In order to measure the therapeutic effectiveness, various sulfur-containing compounds were applied to the plants after they were infected with ginseng anthracnose. Treatment with lime sulfur complex (400 dilution) showed the highest ginseng anthracnose control value, followed by fermented loess-sulfur complex (20 dilution), fermented loess-sulfur complex (40 dilution), and loess-sulfur complex (400 dilution) treatments. These compounds were applied before the outbreak of anthracnose disease in order to measure the preventive effectiveness, and in this case, treatment with fermented loess-sulfur complex (40 dilution) showed the highest control value and it was comparable to the value of the pesticide treatment used as the control in this experiment. CONCLUSION: Fermented loess-sulfur complex could be recommended as an environment-friendly organic material to control the occurrence of ginseng anthracnose.

• Research in Plant Disease
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• v.24 no.1
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• pp.41-51
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• 2018

Since fire blight disease on apple and pear was produced in Korea in 2015, there were no registered chemicals to control against this disease. Instead, several antibacterial chemicals that were registered for other bacterial diseases such as soft rot and bacterial spot have been authorized by Rural Development Administration (RDA). However, these chemicals are not tested efficacy for fire blight disease except damage by those treatments on apple and pear in Korea. Thus, we evaluated efficiency using in vitro and in planta assays of antibacterial chemicals such as antibiotics and copper compounds including kasugamycin, oxytetracycline, oxolinic acid and streptomycin, and copper hydroxide, copper sulfate, oxine copper and tribasic copper sulfate, respectively. We also tested two kinds of biological agents. As expected, significant antibacterial effect was observed in vitro test of both antibiotics and copper-based chemicals. In planta test based on disease severity including ooze and water-soaked formation on immature pears, bacterial populations on blooms, and blight lesion formation in artificially inoculated shoots, kasugamycin, oxytetracycline and streptomycin have been shown the most efficiency among tested antibiotics. Four copper-based chemicals tested in this study, control effects are little bit lower than agricultural antibiotics but they seem to be available to use in terms of winter season. Biocontrol agents were also shown possibility to treat in eco-friendly farms. In addition, there are no antibiotic resistance genes in Korean isolates against antibiotics, which were selected for suppression of fire blight in this study.

• Research in Plant Disease
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• v.18 no.4
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• pp.338-348
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• 2012

Potato late blight caused by Phytophthora infestans Cooke is one of the major diseases in the cultivation of potatoes in Korea. Effect of chitosan preparations (SH-1 and SH-2) was evaluated on the inhibition of mycelial growth of P. infestans, and protective activity using detached potato leaf assay both in vivo and in the field test. SH-1 and SH-2 were showed protective activity of young plant with control values more than 95% potato late blight by inoculation with pathogens under growth chamber conditions. Mycelial growth was inhibited the radial growth over 74% at a concentration of $300{\mu}g/ml$ of both SH-1 and SH-2. Spraying with SH-1 and SH-2 on the leaves for detached leaf assay reduced disease development. The content of total polyphenol in stem was significantly increased by SH-1 and SH-2 application in the field. In field experiments, foliar application with both SH-1 and SH-2 were significantly reduced the development of late blight on potato plants. Control of late blight disease was obtained with control values of 72% and 53% by application of 1% SH-1 and SH-2, respectively, with 4 times at 7 days interval, and reduced with similar disease control values by application with 3 times at 14 days interval compared with untreated control. SH-1 and SH-2 applications increased the fresh weight of potato, and higher grade potatoes were also increased. The results showed that SH-1 and SH-2 applications can be used as eco-friendly natural fungicide for organic farming for the increase of yields and control of late blight.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.481-481
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• 2023

제방은 홍수로부터 주변 주거지와 농경지를 보호하는 가장 전통적이고 기본적인 구조물이다. 개발된 제방보강기술은 파이오폴리머와 골재를 혼합하여 제방표면을 강화하여 월류 등으로 인한 제방붕괴를 대응할 수 있는 친환경 제방보강기술로 제방의 세굴 및 붕괴 등을 억제하는 목적이 있다. 개발 기술은 하천호안 사면 및 제방을 안전하게 보호하기 위한 기술로 치수방재사업과 자연재해 영향을 저감시키는 사업에 활용가능하며 시공성이 수월하여 월류파괴에 대한 대응 기술로 적용이 용이하다. 개발된 기술을 현장에 적용하기 위해서는 기술의 안전성을 확보해야 하므로 현장시범사업 등 실제 적용에 대한 연구가 필요하다. 하지만 월류 파괴는 현장에서 시범사업을 수행할 수 없으므로 본 연구에서는 실규모 실험을 통해 현장 적용성 연구를 수행하였다. 실규모 실험은 안동에 위치한 하천실험센터에서 수행하였으며, 인위적인 월류를 통하여 제방 세굴 및 붕괴 상황을 검토하였다. 실험결과 대조조건으로 식생 제방의 경우 25분경에 붕괴되었고, 개발 기술은 월류 발생 후 2시간 동안 제내지 경사면에서 균열이 발생하지 않았다. 개발기술이 월류파괴에 대해 대응 가능하고 붕괴를 억제할 수 있는 기술로의 실증 결과를 파악 할 수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.37-38
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• 2022

During the past decades, the corrosion of the steel rebar embedded in concrete structure surrounding marine environment is actually problematic and required the suitable preventive method. An eco-friendly corrosion inhibitor mix is investigated to stifle the active corrosion in comparison with other commercial corrosion inhibitors. The hybrid inhibitor enhances the corrosion resistance and the workability of concrete. However, it reduces the compressive strength slightly after 28-day-age. The electrochemical studies and mechanical studies are pointed out the corrosion resistance property, corrosion kinetics, and the mechanical properties of all concrete samples. H-3 is the optimum dose of hybrid inhbitor that meets the demand of both electrochemical property and mechanical property. It performs the noble features due to the formation of optimum amount of P-Zwitterions-(Cl)-Fe complex onto the steel rebar surface.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.104-104
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• 2017

유럽의 폐차 처리 지침, RoHs 및 국내 친환경 소재 부품의 개발이 날로 가속화 되면서 종래 사용해 오던 인산염 피막 등 중금속이 함유된 코팅 재료는 점차 친환경 코팅 용액으로 전환이 되었다. 최근 자동차 산업 등에서 종래 중금속인 $Cr^{+6}$을 함유하지 않는 다양한 코팅 용액이 상용화 되고 있다. 그 중 가장 효율적으로 적용되고 있는 용액이 아연 flake를 첨가하여 희생 양극효과를 가능하게 하여 내식용 코팅 용액으로 상용화 하고 있다. 이 용액에는 내식성을 확보하기 위하여 희생양극이 가능한 소재 인 아연 분말을 첨가하며, 이 분말의 분산성이 소재와 코팅 층의 밀착성, 내식성에 결정적인 영향을 미친다. 특히 산업 현장에서는 아연 분말의 효율적인 분산을 위하여 24시간 이상 교반해야하기 때문에 생산성을 감소시키는 결정적인 요인으로 작용을 한다. 아연 분말의 분산은 용액 내에 첨가하는 각종 첨가제의 종류와 첨가량에 따라 현저하게 분산성이 다르기 때문에 첨가 원소에 대한 연구가 매우 중요하다. 본 연구에서는 서로 다른 이종 합금을 첨가하여 각종 첨가제의 종류 및 첨가량이 분산에 미치는 영향을 조사하였고, 첨가량이 코팅 층의 밀착성 및 내식성에 미치는 영향에 대하여 연구하였다. 분산제 첨가량이 낮을 경우 용액은 두껍게 코팅이 되며 분산 거리가 짧아졌다. 이 경우 코팅 층의 박리가 쉽게 발생하며, 코팅 층이 불균일하였다. 1.7% 첨가량에서 최적분산효과를 얻을 수 있었으며, 1,000시간 이상의 내식성을 확보할 수 있었다. 분산성과 동시에 유동성 확보가 중요하며, 유동성 확보를 위하여 점증제의 첨가량에 대한 변화를 주었다. 최적의 첨가량은 1.5% 이상으로 이 경우 부식 발생시간을 억제할 수 있었다.

• Journal of Applied Biological Chemistry
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• v.55 no.4
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• pp.247-252
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• 2012

This study examined the control effects of amino acid biochemical agent extracted from chicken feathers on Meloidogyne incognita for the purpose of developing an environmentally friendly nematicidal agent that can replace chemical control of root-knot nematodes (RKN). We investigated the lethal effects of J2 juveniles for 19 types of commercial amino acids. As a result, five kinds of amino acids (L-asparagine, L-aspartic acid, L-methionine, L-tyrosine, L-cysteine) showed mortality rate of more than 50% at a concentration of 50 mM. L-asparagine showed the highest mortality rate at 94%. We also investigated the lethal effect of J2 juveniles and suppressive effects of egg hatching by feather amino acids (FAA) biochemical agent. It showed that the mortality rate of J2 juveniles was more than 80% and suppression rate of egg hatching was 74% at 1/50 concentrations of FAA. As a result of conducting a tomato pot culture experiment for 60 days after treating 1/50 concentrations of FAA biochemical agent in rhizosphere soil, it showed that the control effects were 63% of juveniles density in the soil, 59% of egg mass and 61% of root gall index, respectively. Based on the above results, it is considered that the FAA biochemical agent extracted from chicken feathers can be used as an environmentally friendly nematicidal agent of RKN.

• Research in Plant Disease
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• v.29 no.4
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• pp.405-413
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• 2023

Bacterial blight of carrot caused by Xanthomonas hortorum pv. carotae (Xhc) is one of the serious diseases of carrot, of which control measures has not been still established in the domestic farm. In this study, in order to select effective sterilizer for bacterial blight of carrots, three antibiotics such as streptomycin, oxolinic acid, kasugamycin, two copper compounds like copper hydroxide and copper sulfate basic and three rhizobacteria Burkholderia gladioli MRL408-3, Pseudomonas fluorescens TRH415-2 and Bacillus cereus KRY505-3 were selected to investigate their direct antibacterial effects using artificial media, aiming to identify effective pesticides against Xhc. Among them, treated medium with antibiotics such as streptomycin, oxolinic acid, and the antagonistic rhizobacteria MRL408-3 were formed inhibition zone. The agrochemicals and the rhizobacteria MRL408-3, which showed antibacterial effects on carrot leaves, pre-treated on the carrot leaves and then inoculated with Xhc. High control effects were shown on the carrot leaves pre-treated with both streptomycin and oxolinic acid. Scanning electron microscopy images of the carrot leaf surfaces showed that the population of bacteria decreased significantly on leaves pre-treated with streptomycin and oxolinic acid. From these results, it can be inferred that antibiotics like streptomycin and oxolinic acid exhibit superior control effects compared to other agents. This study provides valuable insights towards establishing an effective control system for bacterial blight of carrot.