• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.332-335
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• 2011

As our interests in eco-friendly materials have been significantly increased, the utilization of porous zeolite concrete that has structural functionality and permeability has been increased. In this paper, the mixture of porous concrete and zeolite, which can be used as multirole boulders, was investigated for the suitability of an environment-friendly product by evaluating of the water purification ability. The contamination removal rates of BOD, TOC, T-N, and T-P in stagnant water tank were 70.6, 67.0, 57.7, and 50.6%, respectively. Also for the non-point source pollution with the inflow and the outflow, the removal rates of Zn, Pb, BOD, and COD were 99.9, 90.0, 69.2, and 33.5%, respectively. The performance of the heavy metal contamination removal for the porous zeolite showed better than that of stagnant system. Therefore, it is expected that the installation of the porous zeolite concrete can play a role as an eco-friendly products by its high contamination removal.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2006.05a
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• pp.241-245
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• 2006

본 연구는 유기농 채소와 돈지방, 올리브유를 각각 3%씩 첨가하여 저지방 햄버거 패티의 제조 및 포장방법을 달리하여 $7{\pm}1^{\circ}C$에서 25일간 저장하면서 물리화학적 및 미생물학적 성상을 조사하였다. 모든 처리구들의 pH는 저장기간이 경과함에 따라 증가하다가 저장 15일째를 중심으로 감소하였으며(p<0.05) 저 장기 간 동안 올리브유를 첨 가한 T2시료구가 대조구 및 다른 시료구에 비하여 높은 pH를 유지하였다(p<0.05). TBARS는 대조구에 비하여 각 시료구들이 비교적 낮은 값을 나타내었으며. 특히 식물성 저지방 햄버거 패티의 시료구가 저장기간 동안 가장 낮은 값을 나타내었다(p<0.05). 대조구와 모든 시료구들이 5일 이후부터 증가하는 경향을 보였고 대조구는 저장 15일, 각 시료구는 저장 20일 경과 후 가식권을 벗어났다. 하지만 올리 브유를 첨가한 식물성 저지방 T2시료구의 TBARS value는 저장 20일 이후 가식권을 넘었다. 총균수의 변화를 보면, 각 처리구 중 대조구는 저장 15일 이후부터 7 log CFU/g로 가식권을 넘어섰으며, 각 시료구의 경우에는 저장 20일 경과 후 가식권을 벗어난 것으로 보아 대조구에 비하여 다소 저장기간이 연장됨 을 알 수 있다.

• Journal of the Korean association of regional geographers
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• v.9 no.3
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• pp.329-348
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• 2003

This paper has examined the origin of organic fanning, its development stages, its certification program, and its distributional characteristics in South Korea. Organic agriculture in South Korea originated in the late 1970s as several organic farmers' associations started to be formed. However, the certification of organic farm products, based upon the Codex guideline on organic produce as well as the FAO/WHO find standards, was not institutionalized with the year 2001. A majority of organic products are currently certified as farm products grown with low chemical input. Vegetables grown without any chemical input occupy the largest proportion of the certified produce, while fruits take the smallest. The average size of farms practicing organic agriculture is 0.88 hectare, smaller than the scale of conventional farms being 1.39 hectare. These organic farms are concentrated in Gyeonggi, Chungcheongbuk, and Jeju Province, where organic farmers' associations were first founded. The roles of those associations not only in developing and extending organic farming techniques but also in promoting organic agriculture to consumers were most critical in the regional development of organic farming. It would be desirable for local governments to promote organic farming in tandem with a whole environmental movement.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.521-531
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• 2021

Vacuum Pressure Impregnation (VPI) is a process that enhances physical properties by coating some types of epoxy resins on windings of stator used in large rotators such as generators and motors. During vacuum and pressurization of the VPI process, resin gas is generated by vaporization of epoxy resin. When the tank is opened for curing after finishing impregnation, resin gas is leaked out of the tank. If the leaked resin gas spreads throughout the workplace, there are safety and environmental problems such as fire, explosion and respiratory problems. So, exhaust system for resin gas is required during the process. In this study, a case study of exhaust efficiency by location of vent was conducted using Computational Fluid Dynamics (CFD) in order to design a system for exhausting resin gas generated by the VPI process. The optimal exhaust system of this study allowed more than 90% of resin gas to be exhausted within 1,800 seconds and reduced the fraction of resin gas below the Low Explosive Limit (LEL).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.186-186
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• 2016

수소는 연료전지 등의 에너지원으로 사용될 경우 NOx, SOx, $CO_2$ 등의 한경오염물질, 온실가스를 발생시키지 않기 때문에 친환경 에너지원으로 각광을 받고 있다. 수전해는 수소를 생산하는 가장 간단하고 효율적인 방법 중의 하나로서, 잉여전력 또는 신재생에너지에 의한 전기에너지를 통해 환경오염물질 발생 없이 고순도의 수소를 얻을 수 있으며 분산/대량 생산이 용이하다. 수전해에서 환원전극에서는 수소발생반응이 일어나고, 산화전극에서는 산소발생반응이 일어난다. 이때 주로 산소발생전극 촉매로는 과전압이 작게 걸리고 활성이 우수한 귀금속 계열의 $IrO_2$와 $RuO_2$ 등의 촉매가 현재 사용되고 있다. 본 연구에서는 고분자 용액을 만들어 전기방사를 이용하여 공정변수에 따른 직경과 morphology를 확인하였고, 고가의 귀금속 산화물 대신 저렴한 전이금속산화물인 Cu와 Co를 이용하여 1D 나노섬유를 산소발생 촉매로 합성하였다. 합성된 나노섬유의 구조적, 물리화학적 특성을 분석하고 산소발생반응(OER)에 대한 전기화학적 활성 및 내구성을 평가하였다.

• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.159-165
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• 2009

The synthesis of 2-amino-5-substituted-1,3,4-oxadiazoles 4 were carried out from the electrooxidation of semicarbazone 3 at the platinum electrode under controlled potential electrolysis in an undivided cell. This is an environmentally benign method in the field of synthetic organic chemistry. The non-aqueous solvents acetic acid and acetonitrile and a supporting electrolyte lithium perchlorate were used for the electrolysis in the electrooxidation. The products were structurally charecterised by IR, $^1H$-NMR, $^{13}C$-NMR and elemental analysis.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.25-31
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• 2006

This paper studies the field applicability of the Special Chemical grouting Method (SCM) in reinforcing and reducing permeability of the back of an existing continuous wall. SCM uses double rod which imposes intermediate pressure ($981{\sim}9,810kPa$) to disturb, cut, discharge, and mix the ground. It is observed that a bulb is formed by using cement paste and environmentally friendly injection materials with minimal alkali leaching. Uniaxial compression tests, test for chemical properties and fish poison test are performed. Test results indicate that the method results in higher durability, less leaching through the use of the environmentally friendly injection material and faster mobilization of the strength. In addition, field tests confirm the formation of the bulb and the seepage cutoff wall.

• Journal of Hydrogen and New Energy
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• v.33 no.5
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• pp.515-524
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• 2022

In this study, the on-site hydrogen production process for refueling stations that were not energy-optimized was improved through exergy analysis and heat exchange network synthesis. Furthermore, the process was scaled up from 30 Nm3/h to 150 Nm3/h to improve hydrogen production capacity. Exergy analysis results show that exergy destruction in the SMR reactor and the heat exchanger accounts for 58.1 and 19.8%, respectively. Thus, the process is improved by modifying the heat exchange network to reduce the exergy loss in these units. As a result of the process simulation analysis, thermal and exergy efficiency is improved from 75.7 to 78.6% and 68.1 to 70.4%, respectively. In conclusion, it is expected to improve the process efficiency when installing on-site hydrogen refueling stations.

• Membrane Journal
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• v.27 no.5
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• pp.425-433
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• 2017

As the problems related to the environmental pollution such as carbon dioxide emission are emerging, the need for the renewable energy and environmentally friendly energy is getting intense. Fuel cells are eco-friendly energy generation devices that generate electrical energy and produce water as a sole by-product. Compared to the traditional proton exchange membrane fuel cell (PEMFC), anion exchange membrane alkaline fuel cell (AEMAFC) has a main advantage of possibility to use low cost metal catalysts due to its faster kinetics. The AEM, which conducts $OH^-$ ions, should possess high ion conductivity as well as high chemical stability at high pH conditions. We hereby introduce a crosslinked poly(2,6-dimethyl-1,4-phenylene oxide) having a spacer-type conducting group as novel AEM, and report a high ion conductivity ($67.9mScm^{-1}$ at $80^{\circ}C$) and mechanical properties (Young's modulus : 0.53 GPa) as well as chemical stability (6.8% IEC loss at $80^{\circ}C$ for 1,000 h,) for the developed membrane.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.695-701
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• 2016

Spacecraft propulsion system is a kind of rocket engine that has been developed from the end of 1950s for attitude control and orbit maintenance of satellite. Since the spacecraft propulsion system has to be used for a relatively long time, therefore, stability of propellant and life of thruster could be very important factor for propulsion system design. Recently, green propellant propulsion and all electrical propulsion system have became very important issue, and we also need a development according to well organized plan. In this paper, we will introduce the development status, key technologies and development prospect of spacecraft propulsion system.