• 한국환경과학회지
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• 제31권12호
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• pp.1089-1102
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• 2022

Recently, urbanization has become a serious issue, as there is imbalance between regions and various environmental problems occur intensively in cities. Therefore, cities all over the world are promoting the Green New Deal and trying to realize carbon neutrality. Accordingly, the European Union is leading the creation of carbon-neutral cities by promoting policies aimed at rapidly realizing carbon neutrality. In Korea, projects such as U-City and Smart City have also been promoted continuously for many years, and recently, the projects Smart Green City and Carbon Neutral Green City have been introduced. Therefore, this study aimed to derive directions and implications for future projects based on policies to address climate change by analyzing the guidelines for the Smart Green City project and the project plans of Gimhae-si and Gangjin-gun, which are the leading projects in the Smart Green City business model and are equipped with an extensive budget.

• 한국공간구조학회논문집
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• 제23권3호
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• pp.105-113
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• 2023

The study used the whole-life carbon assessment method to conduct a thorough carbon-neutral evaluation of a standard steel structure. To further assess carbon emissions, 11 design-changed models were evaluated, with changes made to the span between beams and columns. The results of the carbon emission assessment showed savings of approximately 13.1% by implementing the stage of the beyond life cycle. Additionally, the evaluation of carbon emissions through design changes revealed a difference of up to 42.2%. These findings confirmed that recycling and structural design changes can significantly reduce carbon emissions by up to 48.6%, making it an effective means of achieving carbon neutrality. It is therefore necessary to apply the stage of beyond life cycle and structural change to reduce carbon emissions.

• 청정기술
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• 제27권4호
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• pp.325-331
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• 2021

본 연구에서는 미이용 바이오매스인 3급 목재펠렛 및 커피박을 이용하여 바이오카본을 생산하고 이를 통하여 저분자 극성 휘발성 유기화합물인 포름알데하이드 및 아세트알데하이드 제거 성능 실험을 수행하였다. 바이오카본 생산 실험은 이산화탄소를 활성화제로 사용하여 고정층 반응기에서 수행하였다. 활성화 실험 시 반응온도 900 ℃ 및 이산화탄소 1 L min^-1으로 반응조건을 고정하여 진행하였다. 활성화 실험 결과 1급 목재펠렛으로부터 생산한 바이오카본의 BET 비표면적이 약 788 m² g^-1으로 가장 높음을 알 수 있었고 커피박으로부터 생산한 바이오카본이 약 544 m² g^-1으로 가장 낮게 나타났다. 본 실험을 통해 생산된 바이오카본은 대부분 마이크로 기공을 가진 것으로 나타났다. 바이오매스 원료 내 회분의 함량이 낮을수록 바이오카본의 비표면적이 높아지는 것으로 나타났다. 포름알데하이드 및 아세트알데하이드 제거 실험 결과 1급 및 3급 목재펠렛으로 부터 생산한 바이오카본에 비해 커피박으로부터 생산한 바이오카본이 더욱 우수한 흡착 성능을 보여주었다. 추가적으로 상용 첨착 활성탄과 커피박으로부터 생산한 바이오카본의 비교 실험을 진행하였다. 포름알데하이드 제거 성능은 상용 첨착 활성탄이 우수한 반면 아세트알데하이드 제거에는 커피박으로부터 생산한 바이오카본이 우수한 것으로 나타났다.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.240-248
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• 2024

The purpose of this study is to investigate the freezing phenomena in printed circuit heat exchanger (PCHE) for cryogenic liquid hydrogen vaporizer. Local freezing phenomena in hot channels should be avoided in designing PCHE for cryogenic liquid hydrogen vaporizer. Hence, the flow and thermal characteristics of PCHE is experimentally investigated to figure out the conditions under when freezing occurs. To conduct lab-scale PCHE experiment, liquid nitrogen is used as a working fluid in cold channels instead of using liquid hydrogen. Glycol water is used as a working fluid in hot channels. Based on the experimental data, ratio between mass flow rates of cold channels and that of hot channels is proposed as contour map to avoid the freezing phenomena in PCHE.

• KIEAE Journal
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• 제9권3호
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• pp.61-68
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• 2009

Gwangju Metropolitan Government & Ministry of Environment have signed a model city in response to Climate Change agreement. The agreement calls for Gwangju to cut greenhouse gas emissions 10% below 2005 levels by 2015. Gwangju has seen this agreement as an opportunity to cut pollution and conserve the environment as well as to reinvigorate local economy. According to policy of Gwangju, Gwangju held design competition for Gwangju City Arboretum on march, 2009. The purpose of design competition was to give a wide publicity to Gwangju as Hub City of Asian Culture and construct carbon-neutral arboretum in accordance with the policy of 'Low-Carbon and Green Growth'. First of all, a design concept of arboretum is 'winding, round, overlay 'to reflect the landscape of Nam-do which is surrounded by mountains and river flows through the village. Second, the arboretum has five different places with these themes - Forest of Festivals, Health, Nature, Nostalgia, Education and Future. Each place has a symbolic theme park and different flow planning respectively. Third, the most critical point is that the arboretum is a carbon-neutral park. Gwangju arboretum will soon be developed in metropolitan sanitary landfill and constructed as the O2 arboretum based on low carbon strategy. Fourth, the O2 arboretum suggests specialized issue : 'Energy Saving', 'Recycling System', 'Green Network', 'Water System(rainwater maintenance and wetland development)'. Besides, main buildings(greenhouse, visitor center, Nam-do experience exhibition hall, and forest museum) is designed in consideration of harmony with topography character, surroundings. Also, planting will be a multilayer plant based on native landscape trees in consideration of function and the growth characteristics.

• Asian-Australasian Journal of Animal Sciences
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• 제32권1호
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• pp.82-91
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• 2019

Objective: This experiment was conducted to compare the structure and composition of ruminal microorganisms in goats with high and low neutral detergent fibre (NDF) digestibility. Methods: Nineteen crossbred goats were used as experimental animals and fed the same total mixed rations during the 30-day pre-treatment and 6-day digestion trialperiods. All faeces were collected during the digestion period for measuring the NDF digestibility. Then, high and the low NDF digestibility individuals were chosen for the high NDF digestibility group (HFD) and low NDF digestibility group (LFD), respectively. Rumen contents were collected for total microbial DNA extraction. The V4 region of the bacterial 16S rRNA gene was amplified using universal primers of bacteria and sequenced using high-throughput sequencer. The sequences were mainly analysed by QIIME 1.8.0. Results: A total of 18,694 operational taxonomic units were obtained, within 81.98% belonged to bacteria, 6.64% belonged to archaea and 11.38% was unassigned microorganisms. Bacteroidetes, Firmicutes, and Proteobacteria were the predominant microbial phyla in both groups. At the genus level, the relative abundance of fifteen microorganisms were significantly higher (p<0.05) and six microorganisms were extremely significantly higher (p<0.01) in LFD than HFD. Overall, 176 core shared genera were identified in the two groups. The relative abundance of 2 phyla, 5 classes, 10 orders, 13 families and 15 genera had a negative correlation with NDF digestibility, but only the relative abundance of Pyramidobacter had a positive correlation with NDF digestibility. Conclusion: There were substantial differences in NDF digestibility among the individual goats, and the NDF digestibility had significant correlation with the relative abundance of some ruminal microorganisms.

• 분석과 대안
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• 제7권2호
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• pp.179-207
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• 2023

기후변화에 대응한 국제사회의 실천과제인 탄소중립이 각국의 국가 미래 발전을 좌우하는 핵심 산업전략으로 옮겨가고 있다. G2의 경제 대국으로 성장한 중국이지만 고탄소 배출의 산업구조로 인해 이 같은 기후변화 글로벌 이슈를 선도하기 어려울 것이라는 일부 관측이 무색하게도, 중국은 탄소중립을 자국 산업경쟁력 강화를 위한 수단으로 활용하고 있다. 중국정부는 탄소중립 달성을 위한 국정 방침과 이를 이행하기 위한 분야별 세부 계획을 수립, 특히 탄소중립 산업전략을 통해 외부로부터의 기후대응 국제규범 외압을 자국 산업구조의 조정과 신산업 육성을 위한 지렛대로 삼고자 한다. 그러나 이 같은 탄소중립 산업전략은 지역별 경제·산업 수준 등 여건에 따라 중점분야 및 집행력에서 차이가 있을 것으로 예상된다. 이 글에서는 중국 지역별 탄소중립 이행여건과 주요 산업정책의 내용 및 특징을 분석한다. 상이한 경제발전 수준과 산업구조 등에 따라 지역별 탄소배출 규모, 배출원, 효율성에 상당한 차이가 있을 수밖에 없다. 이는 중앙으로부터 주어진 탄소중립 목표를 이행하는 데 있어 상이한 초기 조건과 내생적 요소를 부여하게 되며, 이 같은 주어진 구조적 요인들은 각 지역에 유리한 탄소중립 산업전략의 방향과 중점정책의 조성 및 추진을 제약하게 된다. 특히 탄소중립 이행 관련 지방정부의 정책 자율성 정도를 제약함으로써, 중앙-지방 환경거버넌스의 지역별 특징이 나타날 것이다. 이 같은 점은 보다 정확한 중국 탄소중립 향방을 탐색하기 위해서 국가를 단위로 한 총괄적 연구와 더불어 지역별 모니터링이 긴요함을 시사한다.

• KIEAE Journal
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• 제15권2호
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• pp.5-17
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• 2015

Purpose: The goal of this research is to identify the planning techniques of Smart Green City with Ubiquitous method and carbon-neutral city planning techniques and to induce the main planning techniques through the analysis of relative importance and practical adaptation. Method: First of all, eighteen planning techniques were derived and categorized into three organization systems and six sectors through literature review and FGI analysis considering the applicability of Ubiquitous service for carbon-neutral city planning techniques. Secondly, based on expert surveys and AHP analysis, the importance of Smart Green City planning techniques was evaluated. Thirdly, using case study, six cases related to Smart Green City were analyzed for the current status of application of planning techniques. Lastly, considering the importance of planning techniques and practical aspects, the characteristics of Smart Green City and its implication were estimated. Result: Energy, Resource and Waste and Transportation sector were identified as important sectors for Smart Green City. In addition, 'Construction of Smart Grid', 'System for Utilization of New & Renewable Energy', 'Smart Resource Circulation Management System', 'Establishment of Public Transportation Information System basis', 'Construction of Pedestrian / Bicycle oriented Road Environment' are essential planning techniques to create Smart Green City.

• 한국수소및신에너지학회논문집
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• 제32권4호
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• pp.277-284
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• 2021

This paper deals with multi-objective optimization using response surface method to improve the hydraulic performances of a 2 vane pump for wastewater treatment. For analyzing the internal flow field in the pump, steady Reynolds-averaged Navier-Stokes equations were solved with the shear stress transport turbulence model as a turbulence closure model. The impeller and volute variables were defined in the shape of the 2 vane pump. The objective functions were set to satisfy the total head at the design flow rate as well as to improve the efficiency. The hydraulic performance of the optimally designed shape was verified by numerical analysis results.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.144-149
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• 2022

A cryogenic Mixed Refrigerant Joule-Thomson refrigeration cycle was designed to be applied to the semiconductor etching process with non-flammable constituents. 3-stage cascade refrigerator, single mixed refrigerant Joule-Thomson refrigerator, and 2-stage cascade type mixed refrigerant Joule-Thomson refrigerator are analyzed to figure out the coefficient of performance. Non-flammable mixture of argon(Ar), tetrafluoromethane(R14), trifluoromethane (R23) and octafluoropropane(R218) were utilized to analyze the refrigeration cycle efficiency. The designed refrigeration cycle was adapted to cool down the coolant of HFE7200(Ethoxy-nonafluorobutane, C₄F₉OC₂H₅) with certain constraints. Maximum coefficient of performance of the refrigeration system is obtained as 0.289 for the cooling temperature lower than -100℃. The detailed result of the coefficient of performance according to the mixture composition is discussed in this study.