• Journal of Applied Biological Chemistry
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• v.60 no.2
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• pp.173-178
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• 2017

This study was conducted to investigate the effect of pyroligneous acids on urea hydrolysis for the purpose of inhibiting ammonia volatilization during urea fertilizer application. Different types of synthetic urease inhibitors have been searched and developed, but their use is limited due to varying inhibition effects on soil urease, and environmental problems. In this study, the effect of pyroligneous acids, a natural substance, on urea hydrolysis in soil was evaluated by analyzing inhibition of urease activity. Pyroligneous acids inhibited plant urease and microbial urease activity, as well as soil urease with various urease complex. In addition, pyroligneous acids exhibited non-competitive urease inhibition effect through urease kinetics and inhibited urea hydrolysis in the soil. This study showed that pyroligneous acids treatment with urea fertilizer decreases the loss of urea fertilizer, improves the efficiency of nitrogen application on plant and reduces the amount of nitrogen fertilizers applied in soil.

• Journal of the Korea Convergence Society
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• v.11 no.7
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• pp.157-162
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• 2020

In recent years, laser induced graphene process have been intensively studied for eco-friendly electronic device such as flexible electronics or thin film based energy storage devices because of its simple and effective process. In order to increase the performance and efficiency of an electronic device using such a graphene patterned structure, it is essential to study an optimized laser patterning condition as small as possible linewidth while maintaining the graphene-specific 2-dimensional characteristics. In this study, we analyzed to find the optimal line pattern by using a Ti:sapphire femtosecond laser based photo-thermal reduction process. we tuned intensity and scanning speed of laser spot for generating effective graphene characteristic and minimum thermal effect. As a result, we demonstrated the reduced graphene pattern of 30㎛ in linewidth by using a focused laser beam of 18㎛ in diameter.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.38-45
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• 2007

Laboratory and greenhouse experiments were conducted to determine the herbicidal effect of two types of ${\delta}$-aminolevulinic acid (ALA), microbiologically-produced ALA (Bio-ALA) and synthetically produced ALA (Synthetic-ALA), on plant growth and chlorophyll content of Chinese cabbage. ALA effect on early plant growth was greatly concentration dependant, showing significant inhibition at higher concentrations. Both pre- and post-emergence application of ALA exhibited significant degree of photodynamic phytotoxicity. Older plants with many leaves were more tolerant to ALA than younger plants, showing less injury. No significant difference in herbicidal activity of two types of ALA, Bio-ALA and Synthetic-ALA, on plant height and chlorophyll content of Chinese cabbage was observed. However, residual biological activity and physico-chemical properties of Synthetic-ALA were more stable than those of Bio-ALA. Our results suggest that ALA had herbicidal potential with both pre- and post-emergence application, and that the chemical may be a valuable mean of eco-friendly weed control based on natural microbial substance.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.11a
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• pp.146-148
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• 2003

Bayer 공정은 가성소다를 이용하여 보오크사이트로부터 수산화알루미늄을 추출하는 공정이다. 그러나 보오크사이트 추출 후 1차 침전공정에서 반응한 보오크사이트 잔사는 침전시킴으로써 깨끗한 공정액을 분리하는 데 이때 침전되지 못한 다량의 분산성 고형물이 공정액 중에 존재하게 되는데 이를 분산성 보오크사이트(레드머드) 미립자라하며 보통 80-100mg/$\ell$의 농도를 나타낸다. 그러므로 이를 제거하기 위해 다음 공정인 입상여과필터 공정을 사용하는데 이때 필터링 효율증대를 위해 보조제로써 다량의 소석회(Ca(OH)$_2$)를 투여하여 공정액 중의 고형물을 농도를 8-100mg/$\ell$에서 5mg/$\ell$로 낮추는 공정을 사용하고 있다. 특히 국내 수산화알루미능 제조회사일 KC(주)의 경우 소석회 사용량이 일 10톤, 년간 약 3,600톤을 사용함으로써 소석회의 사용량에 따라 같은 량의 슬러지가 발생되게 된다. 따라서 여과후 발생되는 슬러지의 처리비용 문제(연간 9천만원)와 소석회의 미립자에 의한 공정액의 2차 오염과 제품 품질 저하(quality claim) 및 소석회 사용량에 따른 연간 원료비(연간 3억원) 등의 상당한 문제점을 나타내고 있는 실정이다. 아울러 최근 고품위 수산화알루미늄의 공급 요구에 따라 여과시 정제기준이 점차 낮아져 이제는 1mg/$\ell$ 이하를 유지하여야 하는 근본적인 문제에 봉착해있는 실정이다. 그러므로 본 연구에서는 소석회를 사용하는 입상여과법을 대체하기 위한 신공정개발을 추진하였으며, 그동안 카트리지여과법 등의 다양한 실험 결과로부터 최근 필터 보조제를 첨가하지 않는 물리적 여과방법인 세라믹 막 여과법의 적용 가능성을 확인하고 친환경공정인 세라믹 막 여과 실용화 공정 기술을 개발하였다. 세라믹 막 여과 법은 여과 보조제를 사용하지 않으므로 2차적인 슬러지 발생등의 환경문제를 발생하지 않으며, 공정액에 첨가제를 투입하지 않으므로 순환형 친환경공정으로 각광받을 수 있다. 본 연구에서는 고온, 고농도의 NaOH 수용액의 처리에 적합한 막소재와 발생될 수 있는 제반 문제점 등을 파악하였고, 장기간의 실험을 거쳐 최적 투과 압력(Trans membrane pressue), 세정 조건 및 주기, 막재질에 있어서 보강하여야 할 Point, 최적 운전 조건들을 토출해 내었고, 향후 실제 Plant에 적용할 계획이다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.100-103
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• 2012

The blending method that is an addition of small quantity of fuel was used to increase the performance of green propellant thruster. 90 wt.% hydrogen peroxide as a green propellant was selected, and ethanol was used as a blended fuel. The o/f ratio was chosen as 50 which has higher theoretical performance than 98 wt.% hydrogen peroxide. The chamber temperature of blended hydrogen peroxide was higher than adiabatic chamber temperature of hydrogen peroxide. Therefore, performance can be improved by ethanol blending. Several catalyst and its support were compared to find appropriate catalyst for decomposition and combustion of ethanol blended hydrogen peroxide. As a experimental results, Pt was suitable, but $MnO_2$ had a chamber instability when it was reused. The ${\alpha}-Al_2O_3$ which is high heat-resistant support showed very unstable performance in both Pt and $MnO_2$ catalyst since it has low decomposition performance.

• Journal of Convergence for Information Technology
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• v.11 no.2
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• pp.211-218
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• 2021

The purpose of this study is to develop how to extract essential oil from heartwood of chamaecyparis obtusa and commercialize eco-friendly products using essential oil. Manufacturing process consisted of 8 steps: pulverization, input, pretreatment, extraction(steam distillation), steam emission, cooling, separation, aging. Through the method developed in this study, chamaecyparis obtusa oil with excellent quality in antibacterial effect can be extracted with high productivity. Also, chamaecyparis obtusa spray using this oil had good antibacterial and deodorant effects, and got no irritation results in the clinical test. To commercialize spray, we built a commercial website and performed consumer survey on the site. The survey results showed that respondents had positive attitude toward the products and their messages in the site. When the production standardization through precise quality control and the optimization of composition ratio are accomplished, this study will contribute to commercialize various types of cosmetics and quasi-drugs.

• Journal of the Korean Chemical Society
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• v.65 no.4
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• pp.260-267
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• 2021

Increasing the needs for eco-friendly natural materials, much attention on natural dyes has been attracted. Curcumin, one of abundant natural dyes available in nature, is an eco-friendly molecule found in turmeric. In this study, the colorimetric sensing behavior characteristics of ammonia and hydrogen chloride gases was analyzed using curcumin ink-printed paper and cotton fabric by inkjet printing method. The fabricated paper and fabric were utilized as a colorimetric sensor that can track food spoilage. The color changes of the samples printed on the paper and cotton upon exposure to the toxic gases, the reversibility of the color changes, and the water resistance were investigated. Both samples showed reversible reactions with NH3 and HCl, and small amount of ammonia produced by food spoilage was successfully sensed with naked eyes, confirming its capability to warn food spoilage in our daily life.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.487-498
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• 2010

This article presents an effect of deicer such as $CaCl_2$(calcium chloride) and EFD(Eco-Friendly Deicer) composed by organic acids on the survival and growth of plant. Pine and bush clover which are main natural species on the road side, and young radish and kidney bean which are cultivation species used in this test that responses of survival and growth were analyzed as grade concentration of deicers. Bush clover showed the most sensitive survival response among 4 species to the deicer. Pine growth didn't have statistical significance as the kind of deicers and concentration variation, but growths of bush clover and kidney bean showed growth inhibition in concentration more than 3% of $CaCl_2$ and EFD1. The results of survival and growth for $CaCl_2$(calcium chloride) demonstrated that young radish and pine are tolerant species and bush clover and kidney bean are sensitive species. Although EFD1 manufactured by chemical showed the negative effect on the survival and growth of plants, EFD2 made with waste compost was confirmed that it has the positive influence to the survival and growth of the both sensitive and tolerant plant species for chloride.

• Journal of the Korean Electrochemical Society
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• v.26 no.4
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• pp.64-70
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• 2023

Global warming is getting worse since a dramatic increase in greenhouse gas emissions recently. As a result, the necessity and implementation of carbon neutrality is required more urgently. To do this, among various new and renewable energies, attention in hydrogen arises. Hydrogen as a carbon-free power source is an abundant resource on Earth and is eco-friendly. Eventually, perfectly eco-friendly hydrogen can be obtained through electrolysis of water. However, the catalyst used in the oxygen evolution reaction is rare and expensive, and has a durability issue. Consequently, the development of a non-precious metal catalyst is necessary. In this review paper, we summarize and introduce Co- and Mo- based catalysts among recently announced oxygen evolution catalysts. This will help understand the design of catalyst to increase the activity and durability of non-precious metal catalysts.

• Environmental and Resource Economics Review
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• v.31 no.1
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• pp.1-30
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• 2022

This study is to investigate consumers' acceptance and their willingness to pay for clothes made of materials with low microplastic emissions as an alternative to synthetic fibers made of plastics by applying the contingent valuation method. A nationwide web-based survey was conducted for 1,052 respondents proportional to region, age, and gender during February 2021. More than 75% of the sample expressed intentions to purchase microplastic emission-reducing clothing instead of synthetic fiber clothing, and more than 80% of them have stated their willingness to pay for additional prices. A variation of Heckman's sample selection model was adopted to estimate factors affecting respondents' intentions to pay for additional prices, in which the probit model of intentions to purchase the clothing with alternative materials was used as a sample selection equation. While respondents were sensitive to the amounts of price increases suggested in the CV scenario, they expressed high acceptance and preferences for eco-friendly materials regardless of the microplastic emission-reducing levels. Consumers in the circular economy were willing to pay for the range of 41,000 to 51,000 won for a pair of clothing made with microplastic emission-reducing materials. In addition, as the microplastic emission-reducing rate has increased from 50% to 80%, the willingness to pay estimates were also significantly increased, ranging from 41,000~50,500 to 42,000~51,700 won.