• 한국수소및신에너지학회논문집
• /
• 제16권4호
• /
• pp.391-399
• /
• 2005

This paper deals with the survey of domestic hydrogen production, consumption, and distribution. The amount of domestic hydrogen production and consumption has not been identified, and we survey the amount of domestic hydrogen production and consumption by industries. The hydrogen production industries are classified into the oil industry, the petrochemical industry, the chemical industry, and the other industry. In 2004, the amount of domestic hydrogen production was 972,601 ton, which corresponded to 1.9% of the global hydrogen production. The oil industry produced 635,683 ton(65.4%), the petrochemical industry produced 241,970 ton(24.9%), the chemical industry produced 66,250 ton(6.8%), the other industry produced 28,698 ton(2.9%). The hydrogen consumptions of corresponding industries were close to the hydrogen productions of industries except that of the other industry. Most hydrogen was used as non-energy for raw materials and hydrogen additions to the process. Only 122,743 ton(12.6%) of domestic hydrogen was used as energy for heating boilers. In 2004, 47,948 ton of domestic hydrogen was distributed. The market shares of pipeline, tube trailers and cylinders were 84.4% and 15.6%, respectively. The purity of 31,848 ton(66.4%) of the distributed hydrogen was 99.99%, and 16,100 ton(33.6%) was greater than or equal to 99.999%. Besides domestic hydrogen, we also identify the byproduct gases which contain hydrogen. The iron industry produces COG( coke oven gas), BFG(blast furnace gas), and LDG(Lintz Donawitz converter gas) that contain hydrogen. In 2004, byproduct gases of the iron industry contained 355,000 ton of hydrogen.

• Journal of Plant Biology
• /
• 제25권3호
• /
• pp.123-133
• /
• 1982

The tropic structure and the function of a small pone ecosystem under the tree stand were studied in terms of energy flow. About 28% of total solar radiation was intercepted by the tree canopy over the pond. Primary producers converted 1.1%(3,382 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$) of solar radiation (320,000 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$) into gross primary production. The amount of energy availble to the pond snail was 1,683 kcal.m-2.y-1 of the net production by primary producers and 1,033 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$ of the litter fallen into the pond. The amount of gross secondary production by the pond snail was 245 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$. Judging from these, supply of both net primary production and the litter was indispensable for the maintenance of the pond ecosystem. The total amont of energy as gross primary production plus litter was 4,415 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$(100%). Since the total respiration loss was calculated to be 1,917 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$(43.4%), the rate of energy accumulation in the pond estimated to 56.6%.

• 한국지열·수열에너지학회논문집
• /
• 제15권2호
• /
• pp.10-16
• /
• 2019

In this study, the present regulation of heat metering for the ground source heat pump was investigated. The ground source heat pump has been adopting the heat metering system used in the district heating system for estimating the heating and cooling energy production amount. The accuracy of the present heat metering systems for a water to water ground source heat pump is low, because the system for district heating has a relatively high temperature range comparing with the ground source heat pump operating conditions. Even though the heat amount for the building side should be measured, the heat absorption and extraction amount from or to the ground was measured for the water to air ground source heat pump due to the difficulty of estimating the air side heating and cooling capacity in the present regulation. It is highly recommended to validate the heat metering system to have reliability for the ground source heat pump and develop the system to be applicable water to air ground source heat pump.

• Asian-Australasian Journal of Animal Sciences
• /
• 제17권2호
• /
• pp.263-270
• /
• 2004

A repeated $4{\times}4$ Latin square design was conducted with eight ileal cannulated castrates to examine the effect of source of starch and fiber on nutrient balance and energy metabolism. Pigs were fed on one of the four experimental diets: Control diet (C) mainly based on cooked rice; and diets P, S and W with the inclusion of either raw potato starch, sugar beet pulp or wheat bran supplementation, respectively. With the exception of an increased (p<0.05) energy loss from methane production with diet S observed, no significant differences (p>0.05) in the ratio of metabolizable energy (ME)/digestible energy, the utilization of ME for fat deposition and for protein deposition, energy loss as hydrogen and urinary energy were found between diets. The efficiency of utilization of ME for maintenance was lower (p<0.05) with diets P and S than with diet C. The inclusion of fiber sources (sugar beet pulp or wheat bran) or potato starch reduced the maintenance energy requirement. The fecal energy excretion was increased (p<0.05) with either sugar beet pulp or wheat bran supplementation, while it was unaffected (p>0.05) by addition of potato starch. In comparison with diets C and P, a lowered ileal or fecal digestibility of energy with diets S and W was observed (p<0.05). Feeding sugar beet pulp caused increased (p<0.05) daily production of methane and carbon dioxide and consequently increased energy losses from methane and carbon dioxide production, while it did not influence the daily hydrogen production (p>0.05). An increased (p<0.05) proportion of NSP excreted in feces was seen by the supplementation of wheat bran. Higher NSP intake caused an increased daily amount of NSP in the ileum, but the ileal NSP proportion as a percentage of NSP intake was unaffected by diets. Feeding potato starch resulted in increased daily amount of starch measured in the ileum and the proportion of ileal starch as a percentage of starch intake, while no significant influence on fecal starch was found. Higher (p<0.05) daily amount of fecal starch and the proportion of fecal starch as a percentage of starch intake were found with fiber sources supplementation compared with diets C and P. By increasing the dietary NSP content the fecal amount of starch increased (p<0.01).

• 한국수소및신에너지학회논문집
• /
• 제11권4호
• /
• pp.149-159
• /
• 2000

This paper is concerned with the performence of a steam reformer for 25kW class MCFC, which is compared with the theoretically calculated results at various operating conditions. The theoretical $H_2$ production amount and $CH_4$ conversion rate are calculated with variations of temperature and steam/carbon (S/C) ratio using fortran program, and the actual values are measured from flowmeter and gas chromatography. As a result of the comparison of theoretical and actual values, the theoretical $H_2$ production amount is calculated by $24.4m^3/hr$ at the normal operating condition(LNG $9m^3/hr$, S/C ratio 5, absolute pressure $2.77kg/cm^2$, $610^{\circ}C$), but the actual production amount is only $19.4m^3/hr$, which is 79.5% of the theoretical value. Nevertheless, at the normal operating condition, the reformer for 25kW class MCFC performed well for a 2,100 hr long run operation, constantly producing $H_2$.

• 한국인터넷방송통신학회논문지
• /
• 제23권1호
• /
• pp.139-144
• /
• 2023

최근 많은 제조 기업들이 에너지 비용과 환경 인식의 증가로 인해 에너지 효율에 더 많은 관심을 기울이고 있다. 생산 시스템의 에너지 효율적인 생산스케줄링은 생산에 필요한 에너지 효율을 개선하고 비용을 절감하는 효과적인 방법이다. 본 논문에서는 타이어 생산 문제를 상정하고, 일정한 종류와 형상 모듈 종류 및 각 타이어별 주문량, 생산 모듈의 개수 및 각 종류별 생산시간을 고려하여 생산스케줄링을 구축하는 것을 목표로 하였다. 효과적인 생산스케줄링에 용이하도록 현 상태에서 이용가능한 형상 모듈 종류 및 개수를 고려하여, 다음 단계에서 생산하기로 선택이 가능한 타이어 종류를 부가적인 입력으로 이용하였고, 주문량 이상의 추가 생산이 가능하도록 하였다. 그리하여 평균 62퍼센트 가량의 생산모듈 가동률을 얻었다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제24권4호
• /
• pp.540-572
• /
• 2011

The present review focuses on the effects of energy intake on performance, changes in body tissue during lactation, and metabolic parameters in dairy cows. Especially, pre-partum nutrition and its influence on lactation are emphasized. In recent decades the increase in genetic potential of dairy cows has increased milk yield. This fact sharpens the problem of a negative energy balance in early lactation because the amount of energy required for maintenance and milk production exceeds the amount of energy cows can consume. Around parturition, reduced feed intake reinforces the situation. Continuing negative energy balance causes decreasing milk yield, fertility problems, and incidence of metabolic diseases. Hence, the cow has to rely on body reserves that were stored in late lactation and the dry period. It is evident that the nutritional status pre-partum acts as the key factor for milk yield and fertility parameters in the following lactation. Cows overfed during the foregoing gestation and which have gained large quantities of body fat have lower dry matter intake along with the need to mobilize larger quantities of body reserves in lactation. The milk yield in the following lactation is lower than in cows fed according to their requirements. Cows restrictively fed in late gestation have a higher feed intake in lactation and a lower mobilization of body reserves. The effect of energy intake post-partum plays only a minor role for performance parameters in lactation. Lipid mobilized from body reserves makes a substantial contribution to the energetic cost of milk production in early lactation and adipose tissue undergoes specific metabolic alterations. Adipose tissue is degraded to free fatty acids, which are used in liver for energy purposes. High lipid mobilisation promotes the development of a fatty liver and therefore a reduced gluconeogenesis.

• 한국수소및신에너지학회논문집
• /
• 제27권4호
• /
• pp.447-461
• /
• 2016

Recently, the Renewable Fuel Standard(RFS) has been commenced from July 31, 2015 in the New and Renewable Energy Act for expanding the supply of renewable energy and reduction of national GHG target in Korea. The biodiesel is only a means of implementation for the RFS, therefore the biodiesel supply expansion is important for fulfilling the RFS obligation policy. The major key points of the biodiesl supply are expanding domestic feedstocks due to the over 60% dependence on foreign feedstock and reducing the price of feedstock because of the over 70% occupation of feed stock price in the biodiesl production cost. Therefore, we estimated actual amount of potential feedstocks which are possible to use for biodiesl production in Korea and investigated technical and political improvements for expanding biodiesl. For estimating a potential feedstocks, first selected the potential biodiesl feedstocks by investigating the status of global biodiesl feedstocks and then analyzed the possible potential amount of each feedstock by surveying the generation situations, the distribution structures and the technical level.

• 한국전자통신학회논문지
• /
• 제18권1호
• /
• pp.39-44
• /
• 2023

태양광, 풍력 등의 신재생 에너지는 기상조건 및 환경변화에 민감한 자원이다. 설치위치 및 구조에 따른 설비의 발전량이 달라질 수 있기 때문에 정확한 발전량 예측은 중요하다. 기상 빅데이터를 활용하여 주성분 분석을 기반으로 데이터 전처리 과정을 진행하여 신재생 에너지 발전량 예측 시 영향을 미치는 피처간의 관계를 모니터링하였다. 또한, 본 연구에서는 영향을 미치는 민감도에 따라 데이터셋을 재구성하여 머신러닝 모델에 적용하여 예측도를 테스트하였다. 제안한 모형을 사용하여 신재생 에너지를 대상으로 기상환경에 따라 에너지 발전량을 예측하고 해당 시점의 실제 생산 값과 비교함으로써 랜덤 포레스트 회귀 분석을 적용한 에너지 발전량 예측에 대한 성능을 확인하였다.

• 한국수소및신에너지학회논문집
• /
• 제35권3호
• /
• pp.249-256
• /
• 2024

The cement industry emits a large amount of greenhouse gases compared to other industries, with about 60% of CO₂ emissions from the decarbonation of limestone and about 40% from the combustion of fossil fuels. Therefore, the cement industry needs to reduce greenhouse gases through carbon capture, utilization, and storage technology. Capturing CO₂ and synthesizing it into methanol is feasible and also useful as raw material for the chemical industry and as marine fuel. In this study, We aimed to produce methanol from syngas produced by capturing CO₂ emissions. Process simulations were performed under various conditions such as syngas ratio, temperature, and pressure for the production of synthesis gas and methanol, and the results showed that the optimal amount of methanol production at a synthesis gas ratio of 2.03.