• 한국농공학회논문집
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• 제56권1호
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• pp.89-99
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• 2014

The cultivation of biomass crops is now global demand for decreasing emissions of carbon dioxide ($CO_2$) from fossil fuel. Miscanthus species have been studied as a suitable crop for biomass production, due to its characteristics of fast growth and high biomass. In Korea, Miscanthus species have gained wide attention as an option for biomass production alternative to fossil fuels, recently. New strain of giant Miscanthus has been developed and two large trial sites for the giant Miscanthus production were built in the lower reaches of the Geum River. To evaluate the ecological influence of the giant Miscanthus as an bioenergy crop for the future, we investigated the impact of the construction of the giant Miscanthus production fields on the biota and also compared it with biota in paddy fields near the study sites. The biota including plants, amphibians, reptiles, mammals, avifauna, insects, and bugs was investigated. The plant diversity of the giant Miscanthus production fields was poorer than the paddy fields because the high height of the giant Miscanthus might hinder the growth of other plants. However, the giant Miscanthus production fields serves habitat to animals, leading to rich diversity of animals including avifauna, insects, and bugs. The rich diversity of the animals in the giant Miscanthus production fields coincides with the fact that the giant Miscanthus was grown without any pesticide, herbicide, and fertilizer. This study showed that the giant Miscanthus can influence on biota and further long term study is needed to elucidate the interaction between the diversity of biota and the giant Miscanthus.

• 한국산학기술학회논문지
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• 제10권1호
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• pp.32-38
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• 2009

R744용 초임계 증기압축식 냉동시스템의 작동변수에 대한 기초설계자료를 제공하고자 냉동능력, 압축일량, 성적계수에 대한 사이클 성능분석을 실시하였다. 본 연구에서 고려된 작동변수는 R744 증기압축식 사이클의 과열도, 가스냉각기 출구온도, 증발온도이다. R744의 냉동능력은 과열도가 증가할수록 증가하는 반면, 증발온도와 가스냉각기 출구온도가 증가할수록 감소한다. 압축일량은 R744의 과열도와 냉각압력과 함께 증가하나 증발온도는 증가할수록 감소한다. 그리고 성적계수는 가스냉각기의 출구온도와 증발온도가 증가할수록 증가하는 반면, 과열도는 감소한다. 그러므로, R744용 초임계 증기압축식 냉동시스템의 냉동능력, 압축일량, 성적계수는 과열도, 가스냉각기 출구온도, 증발온도에 영향을 받는 것을 알 수 있었다. 따라서, R744용 초임계 증기압축식 냉동시스템을 설계할 경우에는 이러한 영향을 면밀하게 파악하여야 한다.

• 컴퓨터교육학회논문지
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• 제13권3호
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• pp.77-90
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• 2010

이러닝 표준은 국가 주도의 정책 사업(사이버가정학습 & 디지털교과서)에 적용함으로써 엄청난 예산 절감 효과를 거둔 바 있으며, 중복 개발 방지를 통한 CO2 발생 감소에도 기여할 수 있어 최근 주목받고 있는 그린 패러다임에도 부합하는 분야이다. 특히, 21세기로 접어들어 융합 즉, 컨버전스가 화두로 떠오르며, 그 자체로써 교육과 기술의 융합인 이러닝 표준화 분야는 지속적인 성장이 이루어질 것으로 전망되고 있다. 따라서 본 연구는 이러닝 표준화 분야의 전문가들을 대상으로 델파이 조사를 실시하여 중장기(5개년) 로드맵을 개발함으로써, 향후 표준화 정책 추진을 위한 방향성 도출과 더불어 국제 표준에 대한 전략적인 대응 방안을 마련하고자 하는 목적으로 추진하였다. 아울러, 표준화에 대한 인식 제고를 통해 저변 확대 및 보급 활성화 기반을 조성하는데 기여하고자 하였다.

• 공업화학
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• 제3권1호
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• pp.1-6
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• 1992

메탄올은 저급(低級) 탄소원(炭素源)의 활용(活用)이란 측면(側面)에서, 에너지 저장(貯藏) 운송(運送)이란 관점(觀點)에서 점점 관심(關心)을 끌고 있다. 특히 저급탄소원(低級炭素源)으로부터의 메탄올 합성기술(合成技術)은 이미 상업화(商業化)되어 있는 기술(技術)이기 때문에 더욱 현실적(現實的)인 기술(技術)로 대두되고 있다. 메탄올은 발전(發電), 도시(都市)가스, 화학원료(化學原料) 및 운송연료(運送燃料)로 저급(低級) 탄소원(炭素源)을 활용(活用)할 경우(境遇), 상호(相互) 연계(連繫)하는 매개체(媒介體)로 사용(使用)할 수 있으므로 이를 국익(國益) 차원(次元)에서 C1화학(化學) 기술(技術)을 통한 연계방안(連繫方案)을 기술(技術)하려고 시도하였다. 특히 이산화탄소(二酸化炭素)를 자연계(自然界)에서처럼 일종(一種)의 수소저장(水素貯藏) 수단(手段)으로 메탄올 합성(合成)에 이용(利用)함으로 지구온난화(地球溫暖化) 같은 환경문제(環境問題)를 줄이는 방안(方案)으로 제시(提示)했다.

• 한국환경보건학회지
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• 제32권5호
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• pp.499-505
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• 2006

Bioventing efficiency was compared in a continuous and an intermittent(6hr injection and 6hr rest) air injection mode. Two lab-scale columns which packed with 5 kg of soil artificially contaminated by diesel oil were operated. The columns were maintained at the $25^{\circ}C{\pm}2.5$ in order to minimize the effect of exterior temperature variation. The flow rate of air injection mode were maintained constantly at the flow rate of 10 ml/min. The moisture of the columns was stably maintained at $60{\sim}80%$ of field capacity. The nutrient compounds were added to make C:N:P ratio as 100:10:l. The continuous and intermittent injection modes showed 67.56% and 69.63% reduction of initial TPH concentration during 90 days, respectively. Two venting modes showed similar results in the analysis of the trends of the hydrocarbon utilizing bacterial counts for operating periods. The carbon dioxide production rate of the continuous injection mode was higher than that of intermittent injection mode. The loss of diesel oil by volatilization in the continuous and intermittent injection modes were about 5% and 1%, respectively. The lower volatilization loss in the intermittent injection mode suggested that the biodegradation of TPH in the intermittent injection mode was greater than that of the continuous mode. These results suggested that the intermittent injection mode is more efficient than the continuous venting mode.

• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.90-100
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• 2015

Green technologies such as renewable energy resources, Electric Vehicles and Plug-in Hybrid Electric Vehicles (EVs/PHEVs), electric locomotives, etc. are continually increasing at the existing power network especially distribution levels, which are Medium Voltage (MV) and Low Voltage (LV). It can be noted that the increasing level of green technologies is driven by the reduction emission policies of carbon dioxide ($CO_2$). The green technologies can affect the quality of power, and hence its impacts of are analysed. In practical, the environment such as wind, solar irradiation, temperature etc. are uncontrollable, and therefore the output power of renewable energy in that area can be varied. Moreover, the technology of the EVs/PHEVs is still developed in order to improve the performance of supply and driving systems. This means that these developed can cause harmonic distortion as the control system is mostly used power electronics. Therefore, this paper aims to analyse the voltage variation and harmonic distortion in distribution power network in urban area in Europe due to the combination between wind turbine, hydro turbine, photovoltaic (PV) system and EVs/PHEVs. More realistic penetration levels of SSDGs and EVs/PHEVs as forecasted for 2020 is used to analyse. The dynamic load demands are also taken into account. In order to ensure the accurate of simulation results, the practical parameters of distribution system are used and the international standards such as Institute of Electrical and Electronics Engineers (IEEE) standards are also complied. The suggestion solutions are also presented. The MATLAB/Simulink software is chosen as it can support complicate modelling and analysis.

• Animal cells and systems
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• 제16권6호
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• pp.469-478
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• 2012

Sex hormones have long been considered to play an important role in bone turnover rate, periodontal diseases, and wound healing. We have studied the effect of porcine testis steroid extract (PTSE), an extract of porcine testes, which holds a good ratio of 19-nortestosterone (nandrolone), testosterone, androstenedione, $17{\beta}$-estradiol, and estrone, on the healing rate of a standardized full-thickness linear wound on the back of the rat. Skin punch or carbon dioxide ($CO_2$) laser methods were used to create the deep skin injury in two groups of animals. The animals were treated with the PTSE cream, control cream and Vaseline (control) to find out the effect in re-epithelialization, contraction, and formation of granulation and scar tissues. Histological examination after 21 days showed 100, 87.4, and 80.5% recovery of epidermis, dermis, and hypodermis, respectively in the PTSE-treated animals. Similarly, on the 15th day of treatment, complete healing of intact skin was observed in the PTSE cream-treated animals among the laser radiation group. Even though the beginning of re-epithelialization phase and completion of serum crust formation was also observed in the base cream- and Vaseline-treated animals respectively, the complete healing cycle was observed only in the PTSE-treated group. The white blood cell count in the PTSE-treated group showed that PTSE cream is nontoxic to animals.

• Smart Structures and Systems
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• 제24권4호
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• pp.541-552
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• 2019

Construction development and greenhouse gas emissions have globally required a strategic management to take some steps to stain and maintain the environment. Nowadays, recycled aggregates, in particular ceramic waste, have been widely used in concrete structures due to the economic and environmentally friendly solution, requiring the knowledge of recycled concrete. Also, one of the materials used as a substitute for concrete cement is wollastonite mineral to decrease carbon dioxide (CO2) from the cement production process by reducing the concrete consumption in concrete. The purpose of this study is to investigate the effect of wollastonite on the mechanical properties and durability of conventional composite concrete, containing recycled aggregates such as compressive strength, tensile strength (Brazilian test), and durability to acidic environment. On the other hand, in order to determine the strength and durability of the concrete, 5 mixing designs including different wollastonite values and recovered aggregates including constant values have been compared to the water - cement ratio (w/c) constant in all designs. The experimental results have shown that design 5 (containing 40% wollastonite) shows only 6.1% decrease in compressive strength and 4.9% decrease in tensile strength compared to the control plane. Consequently, the use of wollastonite powder to the manufacturing of conventional structural concrete containing recycled ceramic aggregates, in addition to improving some of the properties of concrete are environmentally friendly solutions, providing natural recycling of materials.

• 인간식물환경학회지
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• 제21권6호
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• pp.445-460
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• 2018

Exposure to indoor air pollution is an emerging world-wide problem, with growing evidence that it is a major cause of morbidity worldwide. Whilst most indoor air pollutants are of outdoor origin, these combine with a range of indoor sourced pollutants that may lead to high pollutant levels indoors. The pollutants of greatest concern are volatile organic compounds (VOCs) and particulate matter (PM), both of which are associated with a range of serious health problems. Whilst current buildings usually use ventilation with outdoor air to remove these pollutants, botanical systems are gaining recognition as an effective alternative. Whilst many years research has shown that traditional potted plants and their substrates are capable of removing VOCs effectively, they are inefficient at removing PM, and are limited in their pollutant removal rates by the need for pollutants to diffuse to the active pollutant removal components of these systems. Active botanical biofiltration, using green wall systems combined with mechanical fans to increase pollutant exposure to the plants and substrate, show greatly increased rates of pollutant removal for both VOCs, PM and also carbon dioxide ($CO_2$). A developing body of research indicates that these systems can outperform existing technologies for indoor air pollutant removal, although further research is required before their use will become widespread. Whilst it is known that plant species selection and substrate characteristics can affect the performance of active botanical systems, optimal characteristics are yet to be identified. Once this research has been completed, it is proposed that active botanical biofiltration will provide a cheap and low energy use alternative to mechanical ventilations systems for the maintenance of indoor environmental quality.

• 유기물자원화
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• 제26권4호
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• pp.5-10
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• 2018

본 연구에서는 압력, 전해질, 유기물 등 가스하이드레이트 부존 지역의 물리화학적 인자가 치환반응에 미치는 영향을 실험적으로 규명하였다. 가스 주입 시 초기 압력이 높을수록 초반 반응속도는 향상되었으나 시간이 지남에 따라 치환효율이 일정한 값으로 수렴하였다. 전해질과 유기물 등의 경우 가스하이드레이트 해리 후 재생성 과정에서 일부 영향을 미치는 것으로 밝혀졌다. 향후 실제 유기성 메탄 하이드레이트가 부존된 퇴적토를 활용한 추가 연구를 통해 국내 해저 지질특성에 적용 가능한 기술 개발이 가능할 것으로 기대된다. 궁극적으로 향후 동해 울릉 분지의 가스하이드레이트 매장 지역 현장 적용을 통해서 유기성 자원인 메탄을 회수하고 활용할 수 있을 것으로 예상된다.