• 신재생에너지
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• 제18권3호
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• pp.1-9
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• 2022

This study analyzed the anticipated supply-and-demand of forest biomass energy (through wood pellets) until 2050, in South Korea. Comparing the utilization rates of forest resources of five countries (United Kingdom, Germany, Finland, Japan, and S. Korea), it was found that S. Korea does not nearly utilize its forest resources for energy purposes. The total demand for wood pellets in S. Korea (based on a power generation efficiency of 38%) was predicted to be 3,629 and 4,371 thousand tons in 2034 and 2050, respectively. The anticipated total wood pellet power generation ratio to target power consumption is 1.13% (5,745 GWh), 1.17% (6,336 GWh), and 1.25% (7,631 GWh) in 2020, 2030, and 2050, respectively. Low value-added forest residues left unattended in forests are called "Unused Forest Biomass" in S. Korea. From the analysis, the total annual potential amount of raw material, sustainably collectible amount, and available amount of wood pellet in 2050 were estimated to be 6,877, 4,814, and 3,370 thousand tons, respectively. The rate of contribution to Nationally Determined Contributions was up to 0.64%. Through this study, the authors found that forest biomass energy will contribute to a carbon neutral society in the near future at the national level.

• 신재생에너지
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• 제18권3호
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• pp.10-22
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• 2022

Forest biomass energy is based on scientific evidence in response to carbon neutrality and the climate crisis, international consensus, and environmental-geographic characteristics of each nation. In this study, the authors aimed to analyze macroscopic forest biomass energy policies for ten major countries. They categorized them into six detailed categories (Sustainable utilization, Cascading Uutilization, Replacement of fossil fuel/Carbon intensive products, Utilization of forest by-products/residues as the source of energy, Contribution to carbon-neutral/climate change, and Biomass combined with CCS/CCUS ). In addition, the surveyed nations have developed a policy consensus on the active use of forest biomass with sustainable forest management except for the cascading utilization category. Furthermore, the authors evaluated the mid to long-term plans of the Korean government for improvements in the policy and legal aspects. As a result, the authors derived four major directions that South Korea should approach strategically in the future (1) secure financial resources for sustainable forest management and stimulating investment in the timber industry, (2) promote unified policies to establish a bio-economy, (3) enhancement of the forest biomass energy system, and (4) reorganization and promotion of strategy centered on the opinions of field experts in internal and external instability.

• Korean Chemical Engineering Research
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• 제60권3호
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• pp.433-438
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• 2022

탄소중립을 달성하기 위한 다양한 정책 및 프로젝트의 실효성을 평가하기 위하여 탄소순환 모델에 기반을 둔 방법을 제안한다. 제안된 모델은 산업혁명 이후 인류에 의한 탄소배출 및 삼림파괴 데이터로부터 대기 중 이산화탄소 농도 증가와 지구평균기온 상승을 적절히 재현함으로써 유효성이 검증되었다. 사례연구로는 삼림벌채, 재식림 및 추가식림에 대한 탄소순환 영향평가를 수행하였다. 대기 중 이산화탄소의 증가는 화석연료사용뿐 아니라 삼림벌채의 영향도 크며, 벌채 직후 재식림을 해도 초기농도로의 복귀는 매우 오래 걸린다는 것이 확인되었다. 제안된 방법은 궁극적으로 미래의 잠재적 기후제어 시뮬레이션에 활용됨으로써 다양한 기후공학 기술의 안전성 검증에 기여할 수 있을 것으로 예상된다.

• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.845-855
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• 2022

In response to climate change, the world is continuing efforts to reduce fossil fuels, expand renewable energy, and improve energy efficiency with the goal of achieving carbon neutrality. In particular, R&D is being made on the value chain covering the entire cycle of hydrogen production, storage, transportation, and utilization in order to shift the energy supply system to focus on hydrogen energy. Hydrogen-based energy sources can produce heat and electricity at the same time, so it is possible to utilize heat energy, which can increase overall efficiency. In this study, calculation of the optimal scale for hydrogen-based cogeneration and the composition of heat sources were reviewed. It refers to a method of the optimal heat source size according to the external heat supply and heat storage to be considered. The results of this study can be used as basic data for establishing a hydrogen-based energy supply model in the future.

• 자원환경지질
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• 제56권1호
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• pp.75-85
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• 2023

The potential sources and spatial distribution of heavy metals and polycyclic aromatic hydrocarbons (PAHs) were investigated in the leaf plants of Al-Zubair city. A total of 14 samples of conocarpus lancifolius plant leaf were collected and analyzed for their heavy metals and PAHs content using inductively coupled plasma mass spectrometry (ICP-MS) and a 7890 Agilent capillary gas chromatograph (GC) respectively. Bioaccumulation factor calculation revealed the highest pollution of heavy metals , due to the activity of a petrochemical in the area. The diagnostic ratio of Ant/(Phe+Ant), BaA/BaA+Chr), In/(In+BghiP), Flu/Pyr, FlA/FlA+Pyr), FlA/FlA+Pyr), ∑LMW/∑HMW are commonly used for determining the origin and source of PAHs in various environmental media. The diagnostic ratio indicated the anthropogenic origin. PAHs with five-to-six membered rings were dominant in the plant leaf, which likely results from anthropogenic activities. The leaves of C. lancifolius have a preponderance of high molecular weight PAHs compared to low molecular weight PAHs, indicating a combustion origin (car exhaust, petroleum emissions, and fossil fuel). C. lancifolius leaves are a reliable indication of atmospheric PAHs absorption. The background level of heavy metals in the city (or the near environment) is in the order of Fe > Cu > Ni > Cr. On the other hand, the bioaccumulation in plant leaves showed greater tendencies as follows: Co>Cd>Zn=As>Cu>Mn>Ni>Pb>Cr>Fe. Cobalt showed high bioaccumulation, indicating strong uptake of Co by plant leaves. These findings point to human activity and car emissions as the primary sources of roadside vegetation pollution in Al-Zubair city.

• Composites Research
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• 제22권1호
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• pp.22-31
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• 2009

최근 화석 연료가 고갈됨에 따라 대체 에너지 개발 연구가 활발히 진행되고 있다. 여러 대체 에너지들 중 풍력 발전기는 바람의 에너지를 전기적 에너지로 바꾸어 주는 시스템으로 매우 친환경적이기 때문에 다양하게 연구되고 있다. 따라서 본 연구의 목표는 500W급 소형 풍력 발전용 블레이드의 개발로서 외국에 비하여 상대적으로 풍속이 낮은 국내와 같은 지역에 적용할 수 있도록 설계 되어야 한다. 본 논문에서는 피로수명을 고려한 고효율 경량화 블레이드의 공력설계 및 구조설계 방법이 제안되었으며, 구조해석으로 선형 정적해석, 좌굴해석, 진동모드해석이 수행되었다. 또한 풍력 발전 시스템에 발생할 수 있는 유체충돌해석을 모사하였다. 해석결과들은 유압시험장비를 이용한 구조시험 빛 성능시험의 결과와 비교되었고, 비교적 잘 일치하여 설계결과의 안전성을 확인하였다.

• Communications for Statistical Applications and Methods
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• 제30권2호
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• pp.119-133
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• 2023

With the rapid growth of the economy and fossil fuel consumption, the concentration of air pollutants has increased significantly and the air pollution problem is no longer limited to small areas. We conduct statistical analysis with the actual data related to air quality that covers the entire of South Korea using R and Python. Some factors such as SO₂, CO, O₃, NO₂, PM₁₀, precipitation, wind speed, wind direction, vapor pressure, local pressure, sea level pressure, temperature, humidity, and others are used as covariates. The main goal of this paper is to predict air quality index (AQI) spatio-temporal data. The observations of spatio-temporal big datasets like AQI data are correlated both spatially and temporally, and computation of the prediction or forecasting with dependence structure is often infeasible. As such, the likelihood function based on the spatio-temporal model may be complicated and some special modelings are useful for statistically reliable predictions. In this paper, we propose several methods for this big spatio-temporal AQI data. First, random effects with spatio-temporal basis functions model, a classical statistical analysis, is proposed. Next, neural networks model, a deep learning method based on artificial neural networks, is applied. Finally, random forest model, a machine learning method that is closer to computational science, will be introduced. Then we compare the forecasting performance of each other in terms of predictive diagnostics. As a result of the analysis, all three methods predicted the normal level of PM_2.5 well, but the performance seems to be poor at the extreme value.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.8-18
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• 2022

With rapid industrialization and population growth, fossil fuel use has increased, which has a significant impact on the environment. Hydrogen does not cause contamination in the energy production process, so it seems to be a solution, but it is essential to find an appropriate storage method due to its low efficiency. In this study, Mg-based alloys capable of ensuring safety and high volume and hydrogen storage density per weight was studied, and Mg₂NiH_x synthesized with Ni capable of improving hydrogenation kinetics. In addition, in order to improve thermal stability, a hydrogen storage composite material synthesized with CaO was synthesized to analyze the change in hydrogenation reaction. In order to analyze the changes in the metallurgical properties of the materials through the process, XRD, SEM, BET, etc. were conducted, and hydrogenation behavior was confirmed by TGA and hydrogenation kinetics analysis. In addition, in order to evaluate the impact of the process on the environment, the environmental impact was evaluated through "Material Life Cycle Assessments" based on CML 2001 and EI99' methodologies, and compared and analyzed with previous studies. As a result, the synthesis of CaO caused additional power consumption, which had a significant impact on global warming, and further research is required to improve this.

• 한국수소및신에너지학회논문집
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• 제34권3호
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• pp.256-266
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• 2023

Hydrogen production can be classified based on the energy source, primary reactor type, and whether or not it emits carbon dioxide. Utilizing color representation proves to be an effective means of expressing these distinctive characteristics. Among the various clean hydrogen production techniques, there has been a growing interest in turquoise hydrogen production, which involves the decomposition of methane or other fossil fuels. This method offers advantages in terms of large-scale production and cost reduction through the sale of solid-carbon byproduct. In this study, an extensive literature review was conducted to select and analyze several promising candidates for turquoise hydrogen production processes. The efficiency and economics of these processes were evaluated using stream data reported in the literature sources. The findings indicate that the levelized cost of hydrogen production (LCOH) is significantly influenced by the sales of byproducts, specifically the solid-carbon and carbon monoxide byproducts.

• 한국수소및신에너지학회논문집
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• 제34권5호
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• pp.431-438
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• 2023

Recently, study on hydrogen is being conducted due to environmental pollution and fossil fuel depletion. High-pressure gas hydrogen commonly used is applied to vehicle and tube trailers. In particular, high-pressure hydrogen storage tank for vehicles must comply with the guidelines stipulated in SAE J2601. There is a charging temperature limitation condition for the safety of the storage tank material. In this study, numerical analysis method were verified based on previous studies and the nozzle angle was changed for thermal management to analyze the increase in forced convection effect and energy uniformity due to the promotion of circulation flow. The previously applied high-pressure hydrogen storage tank has a length/diameter ratio of about 2.4 and was analyzed by comparing the length/diameter ratio with 8. As a result, the circulation flow of hydrogen flowing into the high-pressure hydrogen storage tank is promoted at a nozzle angle of 30° than the straight nozzle and accordingly, the effect of suppressing temperature rise by energy uniformity and forced convection was confirmed.