• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.97-105
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• 2007

This study was conducted to compare the performances of acidogenic fermentation and hydrogen fermentation using bench-scale leaching-bed reactors for organic solid waste. Acidogenic fermenters were operated with dilution rates (D) of 2.0, 3.0 and $4.0d^{-1}$ after employing anaerobic sludge and hydrogen fermenters were operated with D of 2.0, 4.0 and $6.0d^{-1}$ after employing heat-treated anaerobic sludge. The highest chemical oxygen demand (COD) conversion efficiency (56.2%) was obtained in acidogenic fermentation with D of $3.0d^{-1}$. Only volatile fatty acid (VFA) was produced as a metabolite. On the other hand, hydrogen fermentation did not show higher COD conversion efficiency (49.3%) than acidogenic fermentation, but it produced hydrogen gas (5.1% of total COD) which was a clean and environmentally friendly fuel with a high energy yield. Therefore, either acidogenic fermentation or hydrogen fermentation could be applied to organic solid waste depending on the purpose of treatment, which could maximize the economics of anaerobic treatment.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.276-280
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• 2017

In this study, we investigated the effect of sterilization and the neutralization of treated ballast water using seawater electrolysis. The electrolysis apparatus has a cation-selective membrane for passing the cation and a titanium electrode in each cell. We examined the sterilization effect after an incubation period of 24 hr. The oxidation reaction during electrolysis caused, the solution to become strongly acidic due to the generation of a hydroxyl group, and the oxidation reduction potentials(ORP) was increased to 800 - 1200mV. After the reduction reaction, the solution became alkaline(pH 9 - 12), and ORP was decreased to - 900 - - 750 mV. It might be possible to control the pH of ballast water through electrolysis. In addition, we demonstrated the effects of sterilization of ballast water containing generated hypochlorous acid using electrolysis under high ORP condition.

• Journal of the Korean Electrochemical Society
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• v.23 no.4
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• pp.90-96
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• 2020

Polymer electrolyte membrane fuel cells, which convert the chemical reaction energy of hydrogen into electric power directly, are a type of eco-friendly power for future vehicles. Due to the sluggish oxygen reduction reaction and costly Pt catalyst in the cathode, the research related to the replacement of Pt-based catalysts has been vitally carried out. In this case, however, the performance is significantly different from each other and a variety of factors have existed. In this review paper, we rearrange and summarize relevant papers published within 5 years approximately. The selection of precursors, synthesis method, and co-catalyst are represented as a core factor, while the necessity of research for the further enhancement of activity may be raised. It can be anticipated to contribute to the replacement of precious metal catalysts in the various fields of study. The final objective of the future research is depicted in detail.

• Journal of the Korean Institute of Gas
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• v.13 no.5
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• pp.33-38
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• 2009

Synthetic natural gas was producd by the reaction of carbon monoxide and hydrogen via methanation. Ni-Co bimetallic catalyst supported on $Al_2O_3$ for methanation was prepared using deposition-precipitation method. For the comparison, Ni, Co monometallic catalyst was prepared using the same method. The prepared catalysts were characterized by TEM, XRD and TPR and applied to methanation reaction. The catalysts prepared using deposition-precipitation method showed the high metal dispersion. The activity of Ni-Co bimetallic catalyst was higher than that of Ni, Co monometallic catalyst. TPR measurements indicated that Ni-Co bimetallic catalyst had more active hydrogen species than Ni, Co monometallic catalyst due to the synergetic effect in the presence of Ni and Co.

• Membrane Journal
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• v.33 no.4
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• pp.168-180
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• 2023

H₂ generation from renewable sources is crucial for ensuring sustainable production of energy. One approach to achieve this goal is biohydrogen production by utilizing renewable resources such as biomass and microorganisms. In contrast to commercial methods, biohydrogen production needs ambient temperature and pressure, thereby requiring less energy and cost. Biohydrogen production can reduce greenhouse gas emissions, particularly the emission of carbon dioxide (CO₂). However, it is also associated with significant challenges, including low hydrogen yields, hydrodynamic issues in bioreactors, and the need for H₂ separation and purification methods to obtain high-purity H₂. Various technologies have been developed for hydrogen separation and purification, including cryogenic distillation, pressure-swing adsorption, absorption, and membrane technology. This review addresses important experimental developments in dense polymeric membranes for biohydrogen purification.

• Air Cleaning Technology
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• v.28 no.1
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• pp.29-40
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• 2015

중국의 급속한 산업화로 대기, 수질, 폐기물 등 환경오염문제가 심화, 고착화되면서 이를 개선하기 위해 중국 정부는 환경규제를 지속적으로 강화하고 있다. 또한 외국인 투자유치로 제조업 육성에 어느 정도 성공을 거둠에 따라 외국인 투자 유치와 제조업 경영활동에 있어 환경 이슈를 매우 중요시하고 있어 신규 및 사업확장에 제동이 걸리고 있다. 중국은 신규법인수 기준으로 우리나라의 최대 해외직접투자국이며, 제조업종에 대한 투자금액이 전체 투자금액의 88.3%를 차지하고 있다. 중국에 진출한 기업들은 중소기업이 전체 진출기업의 약 90%로 중국의 환경규제 강화는 중국에 진출한 우리 중소기업들에게 직접적인 영향을 미치고 있다. 중국 정부는 분야별 환경목표를 강화하고 오염물질배출 업체를 퇴출시키는 등 강력한 조치를 전개하고 있으며, 중앙 정부의 환경목표 강화 기조와 더불어 해당 지역민의 친환경에 대한 요구가 점차 커짐에 따라, 각 지방정부는 환경 관련 지역 목표 달성을 위해 업체 관리감독을 대폭 강화하고 있는 추세이다. 이러한 중국의 환경규제 강화는 진출 기업이나 진출을 준비하는 기업들의 설비투자비나 오염배출비용 부담 증가 등 상당한 리스크로 작용하고 있으며 향후에도 중국의 환경규제 강화 기조는 지속될 것으로 전망된다. 실제 중국에 진출한 기업들은 환경규제를 직접적으로 체감하고 있다. 규제집행의 강도가 눈에 띄게 높아져 엄격한 기준을 적용받고 처벌수위 역시 높아졌으며, 과거 관시를 통해 원만한 해결이 가능했다면 이제는 환경규제에 대해 원칙적이고 보수적인 공무원의 태도로 인해 관시로도 해결이 어려운 경우가 다반사이다. 또한, 주민들도 환경규제에 대한 인식수준이 높아짐에 따라 미미한 사안에도 즉각적인 반응을 보여 민원제기 사례가 빈번히 발생하고 환경안전 기준이 점점 높아짐에 따라 이에 대응하기 위해 환경안전 설비추가, 친환경연료 사용 등 추가적인 비용이 발생하고 있다. 이에 이미 진출한 기업들은 소재지 환경규제의 강화 전망 및 이로 인한 손실정도를 사전에 파악하고 다양한 옵션에서 대응전략을 마련해야 하며, 향후 중국 진출계획을 가지고 있는 기업들은 진출에 앞서 지역별로 차별화된 시장기회와 환경규제 강도 등 현지 실사를 통한 현장중심 리스크 분석을 실시해야 한다. 또한 이미 진출한 기업 및 진출예정 기업 모두 환경규제가 강화되고 있는 중국에서 사업을 하기 위해서는 법규와 기본원칙을 반드시 준수하고 규제가 더 강화될 것 이라는 기조를 인식할 필요가 있다.

• Journal of Adhesion and Interface
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• v.20 no.4
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• pp.140-145
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• 2019

In view of environmental considerations, the control of carbon dioxide (CO₂) and volatile organic compounds (VOCs) is one of important issues in the film and coating industries. Therefore, UV-curable system has been developed due to minimize emissions of VOCs and reduce CO₂ emission due to low energy consumption from fast curing. Also, biodegradable polymers economically are attractive because of environmental and economic concerns associated with huge waste plastics. In this study, UV-curable polyurethane acrylates with different compositions of biodegradable polylactide (PLA) diol and poly(ethylene glycol) as diols were synthesized and curing reaction of their end-capped acrylates was performed by UV exposure. Tensile strength, elongation, and Tg of the UV-cured polyurethane acrylates increased with PLA diol content in the diol while their hydrophilicity and thermal stability increased with the PEG content. These results indicated a property of UV-cured polyurethane acrylates could be controlled by environment-friendly diols.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4015-4021
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• 2011

The purpose of this study is to investigate the effect of compositional ratio of additives, such as potassium ferrocyanide, aminoacetic acid (=glycine) and 2,2'-dipyridyl, on the physical properties of copper layer deposited by environment-friendly electroless plating reaction. The highest plating rate of copper layer, $9.5mg{\cdot}cm^{-2}{\cdot}hr^{-1}$, was obtained at 20 mg/L of potassium ferrocyanide and 0.01 mol/L of aminoacetic acid, which coincided with the change in the hardness of the copper layer. In the additives used in this study, potassium ferrocyanide was considered to improve the plating rate, aminoacetic acid increased the hardness value of deposited films and 2,2'-dipyridyl enhanced the brightness of copper deposited films.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.63-71
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• 2017

Liquid methane ($CH_4$)/oxygen ($O_2$) bipropellants have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance. In this study, the combustion characteristics of gaseous $CH_4/O_2$ nonpremixed coflow flames in a model combustor with variation of internal pressure are investigated through measuring the combustion stability limits and visualizing flames. Results show that the combustion stability limits are extended and the reaction region is widened with increasing internal pressure of the combustion chamber for fuel-rich condition.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.433-438
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• 2021

Polyethylene is widely used as an agricultural film, but eco-friendly technology is lacking for its decomposition. Thus, recently, much attention has been paid to develop a technology for biological polyethylene decomposition. It has been expected that several oxidation steps will be required in the biological degradation of polyethylene. First, secondary alcohol is formed on the polyethylene chain, and then the alcohol is oxidized to a carbonyl group. In the subsequent process, the carbonyl group is converted to an ester by Baeyer-Villiger monooxygenase (BVMO), and this ester bond is expected to be cleaved by lipase and esterase in the final step. In this work, we reviewed BVMO as one of the promising enzymes for polyethylene decomposition, in terms of its reaction mechanism, classification, and engineering. In addition, we also give a brief perspective on polyethylene decomposition using BVMO.