Elastic strain energy induced by epsilon martensitic transformation and its contribution to the stacking-fault energy of austenite in Fe-15Mn-xC alloys

Lee, S.J.,Han, J.,Lee, C.Y.,Park, I.J.,Lee, Y.K. Elsevier Sequoia 2014 Journal of alloys and compounds Vol.617 No.-

The elastic strain energy and its contribution to the stacking-fault energy (SFE) of γ austenite were quantitatively investigated as a function of the C concentration in Fe-15Mn-(zero to 0.37)C (wt.%) alloys. The elastic strain energy was evaluated in both the homogeneous and inhomogeneous states using measured values for molar volume change, strain, and the elastic properties, which are affected by the γ to ε martensitic transformation. Both the molar volume change and the strain decreased with increasing C concentration, primarily due to the reduction in lattice contraction along the c-axis of the ε phase. The addition of C decreased the room-temperature elastic moduli of the alloys with a dual-phase microstructure of γ and ε. The elastic moduli of the ε phase decreased more rapidly with increasing C concentration than did the elastic moduli of the γ phase. Both the homogeneous and inhomogeneous strain energy values exponentially decreased with increasing C concentration. These values were similar because of the insignificant difference in the shear modulus between the γ and ε phases. The contribution of each energy term to the SFE decreased in the following order: chemical, interfacial, elastic strain, and magnetic energies. Whereas the magnetic energy has been considered for calculating the SFE, the elastic strain energy has been neglected until now. Accordingly, we realized that the elastic strain energy should be considered for more accurate SFE calculation, particularly for Fe-high Mn alloys with C concentrations less than 0.4wt.%.

생산 프론티어 접근을 통한 에너지효율 비교: OECD 국가를 중심으로

강상목 ( Sang Mok Kang ),김해창 ( Hae Chang Kim ) 한국환경경제학회·한국자원경제학회(구 한국환경경제학회) 2011 자원·환경경제연구 Vol.20 No.1

본 연구의 목적은 생산 프론티어 접근을 통하여 OECD 국가의 에너지효율과 경제성장이 에너지수요에 미치는 영향을 비교하는 것이다. 본 연구는 OECD 국가를 대상으로 전통적 에너지 원단위와 생산 프론티어 접근에 의한 에너지효율, 생산 프론티어 상의 효율점에서 에너지 과다 여유분의 존재, 생산의 기술구조 하에서 GDP 증가에 따른 에너지수요 탄력성을 살펴보았다. 첫째, 전통적 에너지 원단위는 방사선 에너지효율과는 상관성이 낮고 여유분 에너지효율, 비방사선 에너지효율과 에너지 최소화 방향의 수평선 에너지효율 등과는 일정한 상관성을 보인다. 에너지 원단위만으로 에너지효율 여부를 판단하는 것은 오류가 있을 수 있다. 특히 방사선 효율에 의한 에너지효율은 대부분의 국가의 에너지효율을 과대평가하는 경향이 있다. 둘째, OECD 국가들이 프론티어 상의 효율적인 생산점에서도 불필요하게 에너지를 소비하는 것이 연평균 17.3%이므로 에너지의 추가 저감이 필요하다. 셋째, OECD 국가의 경제성장에 대한 에너지 탄력성의 평균은 1.1로서 거의 단위 탄력성에 가깝다. 탄력성의 국가별 차이는 존재하고 탄력성이 높은 국가의 에너지수요는 높다. The purpose of the article is to compare the impacts of energy efficiency and economic growth for energy demand through production frontier approach in OECD countries. We compared the traditional energy intensity with energy efficiencies of production frontier approach, slack efficiency on the frontier, and estimated elasticity of energy demand for GDP growth. First, the energy intensity has a low relationship with energy efficiency by radial approach, but has constant correlations with slack energy efficiency, slack-adjusted efficiency by non-radial approach, and energy efficiency by horizon approach. If we measure energy efficiency only with energy elasticity, it may make a mistake. Especially the energy efficiency by radial approach has a tendency to overestimate most OECD countries. Second, as many countries have excess energy consumption of 17.3% even on the points of the frontier, reduction of energy consumption is necessary in addition. Third, the average energy elasticity of OECD countries is 1.1 close to elasticity 1. There exists the difference of elasticity among countries and the energy demands are also high in countries with high elasticity.

가구단위 에너지 수요함수 추정에 관한 연구

김태우,김원년,전재완 한국자료분석학회 2019 Journal of the Korean Data Analysis Society Vol.21 No.5

세계 에너지 수요는 꾸준히 증가하고 있으며, 이에 따라 이산화탄소 배출량 또한 증가하고 있다. 에너지 수요 증가에 따른 에너지 관련 정책을 수립하기 위해서는 에너지 소비구조에 대한 정확한 파악이 선행되어야 한다. 본 연구에서는 통계청의 가계동향조사 자료로 가구단위의 주거용 에너지, 수송용 에너지, 대중교통 수요방정식을 LA/AIDS 모형을 이용하여 SUR 방법으로 추정하였다. 추정결과, 자동차 보유수가 많을수록 주거용과 수송용 에너지 수요는 증가, 대중교통의 수요는 감소했으며, 가구원수가 많을수록 주거용 에너지와 대중교통 수요는 증가하는 것으로 도출되었다. 소득탄력성은 모두 양(+)의 부호로 도출되어 일반적 경제학 이론에 부합하는 결과가 나왔는데, 이전의 연구들에서 사치재의 성격을 보였던 수송용 에너지도 주거용 에너지, 대중교통과 같이 소득탄력성이 1보다 작은 결과가 도출되어 필수재의 성격을 보였다. 자기가격탄력성은 모두 음(-)의 부호로 도출되었으며, 교차가격탄력성을 도출하여 대중교통은 수송용 에너지를 사용하는 개인교통수단과 대체관계임을 밝혔다. Global energy demand is steadily increasing, and CO2 emissions are increasing accordingly. In order to establish energy-related policies in response to the increasing demand for energy, an accurate analysis of the energy consumption structure must be preceded. In this study, the residential energy, transportation energy, and public transport demand equations of household units were estimated by the SUR method using the household trend survey data and the LA/AIDS model. The estimation result showed that the more the number of automobiles, the higher the demand for residential transport energy and the lower the demand for public transport. And also it shows that the higher the number of households, the higher the demand for residential energy and public transport. Income elasticities are all derived with a positive sign, which is consistent with general economic theory. In the previous studies, transport energy, which had the characteristics of luxury goods, also showed the characteristics of necessary goods with results of less than 1 income elasticity such as residential energy and public transportation. All self-price elasticities were derived with a negative sign, and cross-price elasticities were derived to show that public transportation was an alternative to personal transportation using energy for transportation.

A Study on the Effect of Young’s Modulus Modeling on the Energy Conservation in Elastic–Plastic Material Computation

Eun-Ho Lee 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.10

Young’s modulus has a strong effect on the mechanical behavior of elastic–plastic materials, such as elastic stiff ness, elastic recovery, and potential energy. Since springback prediction is important in the sheet metal forming process, many of Young’s modulus studies have been focused on capturing the amount of springback. This work investigated the effect of Young’s modulus modeling focusing on energy conservation point. For this study, three representative concepts of Young’s modulus modeling (fixed modulus, chord modulus, and nonlinear modulus models) were employed. The three modulus models were coupled with the Chaboche kinematic hardening, and implemented into the ABAQUS User-defined material subroutine. The models were used to simulate cyclic loading, monotonic loading conditions, and 2D-draw bending process including the springback prediction. The models showed good agreement with the measured data in the numerical studies. However, in the chord modulus model, a negative potential energy phenomenon was detected during the elastic recovery path, which is unrealistic, while the fixed and nonlinear modulus models keep the energy conservation law. This work discusses the reason for the negative potential energy computation based on the energy dissipation, and presents a numerical method to compensate the negative potential energy.

Sudden Slide Mechanism of a Rock Block in Road Cutting Slope with Soft and Hard Interlayered Bedding Structure Based on Energy Balance Theory

Fuchuan Zhou,Hongmei Tang,Linfeng Wang,Ning Yan 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.10

After the road excavation of the hard and soft interlayered bedding slope in the mountainous region's valley area, the bedding slope often results in a catastrophic phenomenon, especially in the project's construction and operation where existed severe safety hazards. A geo-mechanical two-component model consisting of the slider and the underlying layer is proposed to analyze the rock block instability under the fissure water pressure, the shear deformation, and the compression deformation. The slider's complex stress field is derived by using elastic mechanics. The incremental energy equilibrium Equation is established based on the energy balance theory, and the generalized sliding force relative function of the slider and the generalized shear force relative function of the underlying soft rock are obtained. The deformation energy accumulation, transfer, and energy dissipation characteristics are analyzed. Put a rock slide in the bedding rock cutting slope happened at Jiaojiatan, Pengshui County, Chongqing municipality, China as a case. Results indicate that considering both the compression deformation and the shear deformation of the slider, the kinetic energy, the rapid launch speed of the projectile, the average projectile acceleration, and the failure stroke increase about 15.7 times, 4.0 times, 1.8 times, and 8.9 times respectively than that of only considering the shear deformation, and the dynamic disaster intensity is more severe and worthy of attention. The results that ignored the fissure water pressure and the compressive deformation energy coincide with the existing literature, which verifies the reasonable applied method in this paper. Considering the slider's different displacements and the height-length ratios, when the energy ratio function that represents the ratio of the incremental compression energy to the incremental shear energy concludes that when the range of the height-length ratio is between 0 to 0.95(flat and narrow sliders), the compression energy's contribution to the system’s elastic energy should be taken into consideration. The advantage of the energy balance method applied in the stability analysis of the bedding rock slope is that the potential unstable rock block's status can be predicted dynamically according to the variation of the underlying soft rock's deformation and that the elastic impact dynamic parameters can also be obtained compared with other instability analysis approach.

Mid-Term Energy Demand Forecasting for Manufacturing Sector in Korea

Jeon, Byung Mok 에너지경제연구원 1997 WORKING PAPER Vol.1997 No.1

First of all, this paper analyzes the effects of structural changes and improvements in energy intensities for the energy consumption of the manufacturing sector in Korea using energy elasticity method. Then, we forecasted mid-term energy demand with the 8 scenarios. Major findings are that the rapid increase of energy consumption in the manufacturing sector is mainly due to production increase and structural change to the energy intensive one. This trend intensified from the last of the 1980's, because of expansion of petrochemical and cement industries. The forecasting estimate from the past 24 year tends and intensity improvement assumption shows similar figures to the actual ones. In can be said that the manufacturing sector in Korea is changing to the energy-efficient structure from the mid 1990's. According to the forecasting, energy demand in year 2001 will be 1.4 times larger than that in 1995. This method could be used for a good standard in verifying the validity of other prospects.

Explaining National R&D Effects on Renewable Energy: Evidence from 33 OECD Countries

( Yonghun Jung ),( Seong-hoon Lee ) 한국환경경제학회·한국자원경제학회(구 한국환경경제학회) 2018 한국환경경제학회 학술발표논문집 Vol.2018 No.하계

The purpose of this paper is two-fold: to measure national R&D elasticity of renewable energy and to identify various factors that enhance the national R&D effects on renewable energy. The R&D elasticity of renewable energy for each country and year is empirically estimated from the input demand function of renewable energy theoretically derived from the production function. The national R&D elasticity of renewable energy is estimated using data from 33 OECD countries between 1996-2012. We find that various determinants such as trade openness, Gross Domestic Production (GDP), energy source and portfolio significantly affect the national R&D elasticity of renewable energy. Regression analysis on the relationship between the national R&D elasticity of renewable energy and its determinants are new to the literature, and yield implications for establishing an effective strategy for renewable energy.

Explaining National R&D Effects on Renewable Energy: Evidence from 33 OECD Countries

( Yonghun Jung ),( Seong-hoon Lee ) 한국환경경제학회·한국자원경제학회(구 한국환경경제학회) 2018 한국환경경제학회 학술발표논문집 Vol.2018 No.경제학 공동

The purpose of this paper is two-fold: to measure national R&D elasticity of renewable energy and to identify various factors that enhance the national R&D effects on renewable energy. The R&D elasticity of renewable energy for each country and year is empirically estimated from the input demand function of renewable energy theoretically derived from the production function. The national R&D elasticity of renewable energy is estimated using data from 33 OECD countries between 1996-2012. We find that various determinants such as trade openness, Gross Domestic Production (GDP), energy source and portfolio significantly affect the national R&D elasticity of renewable energy. Regression analysis on the relationship between the national R&D elasticity of renewable energy and its determinants are new to the literature, and yield implications for establishing an effective strategy for renewable energy.

Two-dimensional octagonal phononic crystals for highly dense piezoelectric energy harvesting

Park, Choon-Su,Shin, Yong Chang,Jo, Soo-Ho,Yoon, Heonjun,Choi, Wonjae,Youn, Byeng D.,Kim, Miso Elsevier 2019 Nano energy Vol.57 No.-

<P><B>Abstract</B></P> <P>Piezoelectric energy harvesting at multi-scales has received considerable attention as an attractive powering technology which enables sustainable self-powered operation of small electronics such as wireless sensors. Self-powered wireless sensors for structural health monitoring, biomedical and wearable applications would be great potential applications with high market demand. A key challenge has been insufficient power generation for practical applications, which necessitates a new paradigm in the design of energy harvesting systems. In this work, drastic enhancement of harvesting performance along with energy focusing is demonstrated both analytically and experimentally by introducing metamaterial-based energy harvesting (MEH) systems. Metamaterials, artificially engineered structures, exhibit unique properties including band gap and negative refractive index and thus enable us to manipulate mechanical wave propagations. Wave guide and localization toward a desired position can lead to amplification of harvestable input mechanical energy. In this work, systematic design of two-dimensional octagonal phononic crystals (PnCs) through geometric and band gap optimization process is proposed and followed by experimental demonstration. Energy confinement and localization at the defect of proposed PnCs leads to successful enhancement of harvesting power up to 22.8 times compare to the case without the presence of metamaterial.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Design of two-dimensional octagonal phononic crystals with a defect for highly dense piezoelectric energy harvesting. </LI> <LI> Theoretical analysis of elastic wave propagation behavior to confirm band gap effects as well as energy localization. </LI> <LI> Experimental demonstration of elastic wave generation and visualization and also harvesting performance characterization. </LI> <LI> Drastic enhancement of energy harvesting capability more than 20 times of output power amplification at the level of µWs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

환원분철을 이용한 마찰식 완충기 개발

김병삼 ( Kim Byoung-sam ),박성순 ( Park Seong-soon ),김향우 ( Kim Hyang-woo ) 한국환경기술학회 2004 한국환경기술학회지 Vol.5 No.1

충격이나 진동 등의 충격에너지를 기계 마찰에 따른 열에너지로 변환하여 대기 중에 방출함과 아울러 탄성에너지로 축적한 후 마찰에 따른 열에너지로 점진적으로 방출하여 충격을 감쇠시키는 마찰식 완충기를 개발하는 데 있다. 동하중의 운동에너지를 흡수하여 감쇠시키는 완충기는 그 구동방식에 따라 마찰식 완충기와 유압식 완충기가 많이 사용되었으나, 유압식 완충기는 설치되는 주변의 환경, 즉 온도, 습도, 방사능, 유압유의 점도 등에 의해 사용할 때 많은 제약을 받는다. 유압식 완충기는 내부에 유압유가 충전되므로 내부구조가 복잡하고 사후 관리비용이 증가되며, 상대적으로 중량체로서 설치하기가 힘들다는 문제점이 있다. 또한, 유압유가 누설되는 경우에 동하중이 가해질 때 완충기능을 수행할 수 없게 되어, 배관의 움직임 속도에 따라 완충력이 상이하게 되므로 사용용도가 한정되는 문제점도 있다. 따라서 이러한 문제점 해소를 위해 구조가 간단하면서 유압유가 사용되지 않는 마찰식 완충기의 개발하고자 한다. 본 연구의 결과는 완충기를 사용하고 있는 현장에서 실험적으로 검증할 수 있고, 효율적인 마찰식 완충기 개발을 위한 마찰재 원료배합 및 제조조건을 데이터 베이스화 할 수 있다. The object of this research is developing of the frictional damper(snubber) that converts impulse energy(shock, vibration) into heat energy and elastic energy and gradually emits heat energy into the atmosphere. The development of the frictional damper has the following distinctive feature. It has simple structure, light weight and good response to the vibration. After the frictional damper is set it has no need post control, has to control various damping force, preserves fixed pressure, converts vibration energy into heat energy. Consequently we select following contents of research. A. Inquiry within the framework of the frictional damper B. Development of the friction damper using reduction powder steel. C. Appraisal of an efficiency test of frictional damper As a result, the development of the frictional damper is possible to improve the point at issue; exactly an post control, easiness of the installation, the expected life span. So we are supposed to apply in petro-chemistry factory and a steel mill. We research the combination of raw material and the condition of the production for development of the friction damper systematically. We rejuvenate waste matter in steel mill as the sludge generating steel mill makes into reduction powder steel.