• 한국농공학회지
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• 제37권1호
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• pp.55-64
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• 1995

This paper presents analytic results of energy sequestered for the forcing cultural Cu- cumber and the others production system with the input-output tables method in the suthern parts of Korea. In this study an attempt is made to evaluate input of direct and indirect energy, output of yield energy and net energy in order to achieve increased energy productivity under P E greenhouse. Cultural practices were grouped soil and soilless with perlite for vegetable production. The results from this study are summarized as follows : 1. Total energy inputs in cucumber production were calculated to be 510 GJ/l0a(di- rect energy : 480 GJ/lOa, indirect energy : 30 GJ/lOa) from soil culture and 440 GJ/ 10a(direct energy : 420 GJ/lOa, indirect energy : 20 GJ/lOa) from soilless culture in perlite hydroponics. 2. Energy outputs from cucumber and biomass were 7 GJ/lOa and 120 GJ/lOa at a uniform rate respectively. 3. Heating fuel as diesel is a major energy inputs approaching 90% of the total energy requirements for cucumber production. 4. Net energy in cucumber production was calculated to be 503 GJ/lOa from soil cul- ture and 431 GJ/lOa from soilless culture. Net energy productivity was maintained costantly as 0.98. 5. Energy productivity in cucumber was calculated to be 0.029 kg/MJ from soil culture and 0.043kg/MJ from soilless culture, while energy efficiency was 0.012 and 0.015 respectively. It is expected that a soilless cultural production system seems to be reduc- tive in seguestered energy input by 13%.

• Advances in Energy Research
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• 제2권1호
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• pp.11-20
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• 2014

This paper examines the climatic and technical feasibilities of zero energy buildings in Seoul, Shanghai, Singapore and Riyadh. Annual and seasonal energy demands of office buildings of various scales in the above cities were compared. Using optimally tilted rooftop PV panels, solar energy production potentials of the buildings were estimated. Based on the estimates of onsite renewable energy production and building energy consumption, the energy self-sufficiencies of the test buildings were assessed. The economic feasibilities of the PV systems in the four locations were analyzed. Strategies for achieving zero energy buildings are suggested.

• Advances in Energy Research
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• 제3권2호
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• pp.97-115
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• 2015

Energy holds key to economic growth and prosperity of India. Currently, India has very high-energy import dependence, especially in the case of crude oil (80%) and natural gas (40%). Even coal import has been increasing over the years. Considering India's population growth, emphasis on manufacturing, production, and service industry, energy consumption is bound to increase. More fossil energy consumption means greater dependence on energy import leading to widening trade deficit and current account deficit. Therefore, exploitation of indigenous renewable energy production is necessary. The paper reviews the progress and growth of renewable energy production, distribution, and consumption in India. The paper highlights some of the enablers of renewable energy in India. The authors discuss the opportunities and challenges of increasing share of renewable energy to reduce energy import and address issues of energy security in India. The findings suggest that India is ready for a quantum leap in renewable production by 2022.

• 자원ㆍ환경경제연구
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• 제10권2호
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• pp.135-159
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• 2001

This study analyses the energy consumption increase by using a physical production index (PPI) based decomposition method. The energy efficiency of the Korean industry deteriorated to a large extent in the 1992 to 1997 period. This outcome, however, does not contradict the result of a previous study that the physical energy intensities (measured by energy use per production unit) decreased in four Korean energy intensive industries such as steel, cement, petrochemical and pulp and paper in the same period. Although the physical energy intensities in four industries considered decreased significantly, the energy efficiency of the Korean industry deteriorated because the increase in the value-added production was smaller than that in the physical production except for the steel industry. This outcome suggests that the reduction in the physical energy intensity alone will not result in reducing the economic energy intensity, thereby reducing the increase in the energy consumption of the Korean industry. Therefore, it necessitates to restructure the Korean industry towards a higher value-added production and to strengthen energy efficiency improvement efforts in the Korean industry. As the overinvestment in the energy intensive industries caused a deep price fall of Korean products and a reduction of the value added of the Korean industry and with it an increase in the economic energy intensity, a decrease in this intensity will highly depend on reducing the overcapacity in the energy intensive industries which was partly responsible for the currency and economic crisis of 1997.

• 한국태양에너지학회 논문집
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• 제27권1호
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• pp.1-9
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• 2007

This paper reveals both the operational situation and the cause of the error occurred in wind turbine generator system of Hangwon wind farm in Jeju island. The four wind turbines were selected for this work, and the monitored period was for six months. Wind resource in the wind farm was analyzed, and the estimated energy production was compared with the actual energy production. As a result, with a decrease of system error, the estimated energy production was in good agreement with the actual energy production. The errors occurring in components such as gearbox and hydraulic motor affected the Availability of the wind turbine. Also, poor external conditions such as a strong wind, lightning and gust caused a standstill of wind turbines.

• 한국산업융합학회 논문집
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• 제27권2_1호
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• pp.269-276
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• 2024

Many countries across the world are making efforts beyond reducing CO₂ levels and declaring 'net zero,' which aims to cut greenhouse gas emissions to zero by not emitting any carbon or capturing carbon, by 2050. Hydrogen is considered a key energy source to achieve carbon neutrality goals. Korean companies are also interested in building overseas green ammonia production plants and importing hydrogen into Korea in the form of ammonia. Green hydrogen production uses renewable energy sources such as solar and wind power, but the variability of power production poses challenges in plant design. Therefore, optimization of the configuration of a green ammonia production plant using renewable energy is expected to contribute as basic information for securing the economic feasibility of green ammonia production.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1288-1294
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• 2022

Hydrogen as an environmentally friendly energy carrier has received special attention to solving uncertainty about the presence of renewable energy and its dependence on time and weather conditions. This material can be prepared from different sources and in various ways. In previous studies, fossil fuels have been used in hydrogen production, but due to several limitations, especially the limitation of the access to this material in the not-too-distant future and the great problem of greenhouse gas emissions during hydrogen production methods. New methods based on renewable and green energy sources as energy drivers of hydrogen production have been considered. In these methods, water or biomass materials are used as the raw material for hydrogen production. In this article, after a brief review of different hydrogen production methods concerning the required raw material, these methods are examined and ranked from different aspects of economic, social, environmental, and energy and exergy analysis sustainability. In the following, the current position of hydrogen production is discussed. Finally, according to the introduced methods, their advantages, and disadvantages, solar electrolysis as a method of hydrogen production on a small scale and hydrogen production by thermochemical method on a large scale are introduced as the preferred methods.

• 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.

• Architectural research
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• 제18권2호
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• pp.59-64
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• 2016

Since the massive power outages that hit across the nation in September 2011, a growing imbalance between energy supply and demand has led to a severe backup power shortage. To overcome the energy crisis which is annually repeated, a policy change for deriving energy supply from renewable energy sources and a demand reduction strategy has become essential. Buildings account for 18% of total energy consumption and have great potential for energy efficiency improvements; it is an area considered to be a highly effective target for reducing energy demand by improving buildings' energy efficiency. In this regard, retrofitting buildings to promoting environmental conservation and energy reduction through the reuse of existing buildings can be very effective and essential for reducing maintenance costs and increasing economic output through energy savings. In this study, we compared the energy reduction efficiency of national power energy consumption by unit production volume based on thermal power generation, renewable energy power generation, and initial and operating costs for a building retrofit. The unit production was found to be 13,181GWh/trillion won for bituminous coal-fired power generation, and 5,395GWh/trillion won for LNG power generation, implying that LNG power generation seemed to be disadvantageous in terms of unit production compared to bituminous coal-fired power generation, which was attributable to a difference in unit production price. The unit production from green retrofitting increased to 38,121GWh/trillion won due to the reduced energy consumption and benefits of greenhouse gas reduction costs. Renewable energy producing no greenhouse gas emissions during power generation and showed the highest unit production of 75,638GWh/trillion won, about 5.74 times more effective than bituminous coal-fired power generation.

• 한국수소및신에너지학회논문집
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• 제7권2호
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• pp.193-206
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• 1996

The simplest and lightest element-hydrogen is an alternative fuel which provides a clean and renewable energy source. Hydrogen can be used to power gas-type appliance and modified automobiles with water vapor as the only byproduct of combustion. Historically, production of hydrogen from coal was one of the mass production technology of hydrogen. In this paper, the status of hydrogen production process from coal was investigated to review the current situation of hydrogen production and utilization.