• Title/Summary/Keyword: Stress gradient

Search Result 515, Processing Time 0.022 seconds

A Hydro-Mechanical Basic Study on the Effect of Shut-in on Injection-Induced Seismic Magnitude (유체 주입 중단이 유발 지진 규모에 미치는 영향에 대한 수리역학적 기초 연구)

  • Yim, Juhyi;Min, Ki-Bok
    • Tunnel and Underground Space
    • /
    • v.32 no.3
    • /
    • pp.203-218
    • /
    • 2022
  • A hydro-mechanical study was performed to analyze the relationship between the magnitude of injection-induced seismicity and shut-in. In hydraulic analysis, the suspension of fluid injection makes the pore pressure gradient smaller while the pore pressure at the pressure front can reach the critical value for several hours after shut-in, which leads to the additional slip with wider area than during injection. The hydro-mechanical numerical analysis was performed to model the simplified fault system, and simulated the largest magnitude earthquake during shut-in stage. The effect of the abrupt suspension of fluid injection on the large magnitude earthquake was investigated in comparison with the continuous injection. In addition to the pore pressure distribution, it was found that the geometry of multiple faults and the stress redistribution are also important in evaluating the magnitude of the induced seismicity.

Stabilization of High Nickel Cathode Materials with Core-Shell Structure via Co-precipitation Method (공침법을 통하여 합성된 코어-쉘 구조를 가지는 하이 니켈 양극 소재 안정화)

  • Kim, Minjeong;Hong, Soonhyun;Jeon, Heongkwon;Koo, Jahun;Lee, Heesang;Choi, Gyuseok;Kim, Chunjoong
    • Korean Journal of Materials Research
    • /
    • v.32 no.4
    • /
    • pp.216-222
    • /
    • 2022
  • The capacity of high nickel Li(NixCoyMn1-x-y)O2 (NCM, x ≥ 0.8) cathodes is known to rapidly decline, a serious problem that needs to be solved in a timely manner. It was reported that cathode materials with the {010} plane exposed toward the outside, i.e., a radial structure, can provide facile Li+ diffusion paths and stress buffer during repeated cycles. In addition, cathodes with a core-shell composition gradient are of great interest. For example, a stable surface structure can be achieved using relatively low nickel content on the surface. In this study, precursors of the high-nickel NCM were synthesized by coprecipitation in ambient atmosphere. Then, a transition metal solution for coprecipitation was replaced with a low nickel content and the coprecipitation reaction proceeded for the desired time. The electrochemical analysis of the core-shell cathode showed a capacity retention of 94 % after 100 cycles, compared to the initial discharge capacity of 184.74 mA h/g. The rate capability test also confirmed that the core-shell cathode had enhanced kinetics during charging and discharging at 1 A/g.

Growth and Quality Characteristics in Response to Elevated Temperature during the Growing Season of Korean Bread Wheat

  • Chuloh Cho;Han-Yong Jeong;Yulim Kim;Jinhee Park;Chon-Sik Kang;Jong-Min Ko;Ji-Young Shon
    • Proceedings of the Korean Society of Crop Science Conference
    • /
    • 2022.10a
    • /
    • pp.124-124
    • /
    • 2022
  • Wheat (Triticum aestivum L.) is the major staple foods and is in increasing demand in the world. The elevated temperature due to changes in climate and environmental conditions is a major factor affecting wheat development and grain quality. The optimal temperature range for winter wheat is between 15~25℃, it is necessary to study the physiological characteristic of wheat according to the elevated temperature. This study presents the effect of elevated temperature on the yield and quality of two Korean bread wheat (Baekkang and Jokyoung) in a temperature gradient tunnel (TGT). Two bread wheat cultivars were grown in TGT at four different temperature conditions, i.e. TO control (near ambient temperature), T1 control+1℃, T2 control+2℃, T3 control+3℃. The period from sowing to heading stage has accelerated, while the growth properties including culm length, spike length and number of spike, have not changed by elevated temperature. On the contrary, the number of grains per spike and grain yield was reduced under T3 condition compared with that of control condition. In addition, the. The grain filling rate and grain maturity also accelerated by elevated temperature (T3). The elevating temperature has led to increasing protein and gluten contents, whereas causing reduction of total starch contents. These results are consistent with reduced expression of starch synthesis genes and increased gliadin synthesis or gluten metabolism genes during late grain filling period. Taken together, our results suggest that the elevated temperature (T3) leads to reduction in grain yield regulating number of grains/spike, whereas increasing the gluten content by regulating the expression of starch and gliadin-related genes or gluten metabolism process genes expression. Our results should be provide a useful physiological information for the heat stress response of wheat.

  • PDF

Geometric Thermoelectric Generator Leg Shape Design for Efficient Waste Heat Recovery (효율적인 폐열 회수를 위한 기하학적 열전소자 다리 설계)

  • Hyeon-Woo Kang;Jung-Hoe Kim;Young-Ki Cho;Won-Seok Choi;Hyun-Ji Lee;Hun-Kee Kim
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.19 no.3
    • /
    • pp.589-602
    • /
    • 2024
  • Thermoelectric generator (TEG) generally do not have high heat conversion efficiencies. The performance of a thermoelectric generator module depends on the shape of the legs as well as the properties of the material and the number of legs. In this study, the leg shapes of thermoelectric elements are modeled into various geometric structures such as cylinder and cube shaped to efficiently harvest waste heat, and the electrical characteristics are compared numerically. The temperature gradient and power generation according to the bridge shape are found to be highest at the existing Cube shape. As a result of comparing the power generation using the cooling effect, the Cone shape was the highest in natural convection and the Hourglass shape was highest in forced convection. Research results confirm that geometry can affect the efficiency of thermoelectric generators.

Free vibration analysis of Bi-Directional Functionally Graded Beams using a simple and efficient finite element model

  • Zakaria Belabed;Abdeldjebbar Tounsi;Abdelmoumen Anis Bousahla;Abdelouahed Tounsi;Mohamed Bourada;Mohammed A. Al-Osta
    • Structural Engineering and Mechanics
    • /
    • v.90 no.3
    • /
    • pp.233-252
    • /
    • 2024
  • This research explores a new finite element model for the free vibration analysis of bi-directional functionally graded (BDFG) beams. The model is based on an efficient higher-order shear deformation beam theory that incorporates a trigonometric warping function for both transverse shear deformation and stress to guarantee traction-free boundary conditions without the necessity of shear correction factors. The proposed two-node beam element has three degrees of freedom per node, and the inter-element continuity is retained using both C1 and C0 continuities for kinematics variables. In addition, the mechanical properties of the (BDFG) beam vary gradually and smoothly in both the in-plane and out-of-plane beam's directions according to an exponential power-law distribution. The highly elevated performance of the developed model is shown by comparing it to conceptual frameworks and solution procedures. Detailed numerical investigations are also conducted to examine the impact of boundary conditions, the bi-directional gradient indices, and the slenderness ratio on the free vibration response of BDFG beams. The suggested finite element beam model is an excellent potential tool for the design and the mechanical behavior estimation of BDFG structures.

Structural RC computer aided intelligent analysis and computational performance via experimental investigations

  • Y.C. Huang;M.D. TuMuli Lulios;Chu-Ho Chang;M. Nasir Noor;Jen-Chung Shao;Chien-Liang Chiu;Tsair-Fwu Lee;Renata Wang
    • Structural Engineering and Mechanics
    • /
    • v.90 no.3
    • /
    • pp.253-261
    • /
    • 2024
  • This research explores a new finite element model for the free vibration analysis of bi-directional functionally graded (BDFG) beams. The model is based on an efficient higher-order shear deformation beam theory that incorporates a trigonometric warping function for both transverse shear deformation and stress to guarantee traction-free boundary conditions without the necessity of shear correction factors. The proposed two-node beam element has three degrees of freedom per node, and the inter-element continuity is retained using both C1 and C0 continuities for kinematics variables. In addition, the mechanical properties of the (BDFG) beam vary gradually and smoothly in both the in-plane and out-of-plane beam's directions according to an exponential power-law distribution. The highly elevated performance of the developed model is shown by comparing it to conceptual frameworks and solution procedures. Detailed numerical investigations are also conducted to examine the impact of boundary conditions, the bi-directional gradient indices, and the slenderness ratio on the free vibration response of BDFG beams. The suggested finite element beam model is an excellent potential tool for the design and the mechanical behavior estimation of BDFG structures.

Impacts of Ocean Currents on the South Indian Ocean Extratropical Storm Track through the Relative Wind Effect

  • Hyodae Seo;Hajoon Song;Larry W. O'Neill;Matthew R. Mazloff;Bruce D. Cornuelle
    • Journal of Climate Change Research
    • /
    • v.34 no.22
    • /
    • pp.9093-9113
    • /
    • 2021
  • This study examines the role of the relative wind (RW) effect (wind relative to ocean current) in the regional ocean circulation and extratropical storm track in the south Indian Ocean. Comparison of two high-resolution regional coupled model simulations with and without the RW effect reveals that the most conspicuous ocean circulation response is the significant weakening of the overly energetic anticyclonic standing eddy off Port Elizabeth, South Africa, a biased feature ascribed to upstream retroflection of the Agulhas Current (AC). This opens a pathway through which the AC transports the warm and salty water mass from the subtropics, yielding marked increases in sea surface temperature (SST), upward turbulent heat flux (THF), and meridional SST gradient in the Agulhas retroflection region. These thermodynamic and dynamic changes are accompanied by the robust strengthening of the local low-tropospheric baroclinicity and the baroclinic wave activity in the atmosphere. Examination of the composite life cycle of synoptic-scale storms subjected to the high-THF events indicates a robust strengthening of the extratropical storms far downstream. Energetics calculations for the atmosphere suggest that the baroclinic energy conversion from the basic flow is the chief source of increased eddy available potential energy, which is subsequently converted to eddy kinetic energy, providing for the growth of transient baroclinic waves. Overall, the results suggest that the mechanical and thermal air-sea interactions are inherently and inextricably linked together to substantially influence the extratropical storm tracks in the south Indian Ocean.

Growth characteristics and distribution pattern of a brackish water clam, Corbicula japonica along an estuarine salinity gradient in Seomjin River (섬진강 하구역에서 염분구배에 따른 일본재첩의 분포와 성장특성)

  • Baek, Seung Ho;Seo, JIn-Young;Choi, Jin-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.16 no.10
    • /
    • pp.6852-6859
    • /
    • 2015
  • The purpose of this study was to determine the growth characteristics and distribution pattern of a brackish water clam Corbicula japonica in Seomjin River. Field samples were taken from 14 stations with salinity gradients during spring. Salinity at the bottom layer ranged from 1.0 psu to 32.9 psu, with low salinities in the upper area of the river. In particular, salinity at St.11 was decreased drastically to be ca. 15.0 psu, indicating an intermediate salinity zone. The distribution pattern of C. japonica was related to the salinity gradient, with the highest densities of $2,102ind.m^{-2}$ at Station 13, followed by $1,507ind.m^{-2}$ at Station 11. Here, we focused on the growth characteristics of collected C. japonica collected at two stations with different salinity values. The relationship between shell length and total weight was highly correlated ($R^2=0.91$, P<0.001) at Station 13 compared to that at Station 11 ($R^2=0.72$, P<0.001). On the other hands, the degree of correlation between shell length and shell height (SH) or shell width (SW) at Station 11 (SH: $R^2=0.91$, P<0.001; SW: $R^2=0.69$, P<0.001) was higher than that at Station 13 (SH: $R^2=0.64$, P<0.001; SW: $R^2=0.48$, P<0.001). In addition, fatness index of C. japonica at Station 13 was significantly (P < 0.001) higher than that at St. 11 (t-test value=-22.8, p<0.001). This implies that C. japonica at Station 13 might have enhanced their somatic growth, whereas C. japonica at Station 11 might have this kind of defense mechanism their internal organization against the salinity stress. Ecologically, this kind of defense mechanism of C. japonica against salinity flucuation may play an important role in their survival strategy.

Photosynthesis and Growth of Southern-type Garlic (Allium sativum L.) in Response to Elevated Temperatures in a Temperature Gradient Tunnel (온도구배터널 내 상승온도에 의한 난지형 마늘(Allium sativum L.)의 광합성 및 생육 특성의 변화)

  • Oh, Seo-Young;Moon, Kyung Hwan;Song, Eun Young;Shin, Minji;Koh, Seok Chan
    • Korean Journal of Agricultural and Forest Meteorology
    • /
    • v.21 no.4
    • /
    • pp.250-260
    • /
    • 2019
  • This study assessed clove germination, shoot growth, photosynthesis and bulb development of southern-type garlic (Allium sativum L.) in a temperature gradient tunnel (TGT), to examine the impacts of increases in temperature on the growth of garlic and find a way to minimize them. The temperatures in the middle and outlet of the TGT were 3.2℃ and 5.8℃ higher, respectively, than the ambient temperature at the tunnel inlet. The germination of garlic cloves was late at temperatures of ambient+3℃ (in the middle of the TGT) and ambient+6℃ (at the outlet) than at ambient temperature (at the inlet). However, bolting and the timing of maximum leaf number per plant were faster at ambient+3℃ or +6℃ than at ambient temperature. Shoot growth was generally greater at ambient temperature. Bulb growth did not significantly differ according to cultivation temperatures, but fresh and dry weights were slightly higher at ambient temperature and ambient+3℃ in the late growth stage. The photosynthesis rate (A), stomatal conductance (gs), and transpiration rate (E) were higher at ambient+3℃ than at ambient temperature. Furthermore, at ambient+3℃, the net photosynthetic rate (Amax) was high, while the dark respiration rate (Rd) was low. At ambient temperature and ambient+3℃, bulb development was healthier, resulting in better productivity and more commercial bulbs, while at ambient+6℃, the bulbs were small and secondary cloves developed, resulting in low commercial value. Therefore, at elevated temperatures caused by global warming, it is necessary to meet the low-temperature requirements before clove sowing, or to delay the sowing time, to improve germination rate and increase yield. The harvest should also be advanced to escape high-temperature stress in the bulb development stage.

Interfacial Evaluation of Single-Carbon Fiber/Phenolic and Carbon Nanotube-Phenolic Composites Using Micromechanical Tests and Electrical Resistance Measurements (미세역학시험법과 전기저항 측정을 이용한 탄소섬유/페놀수지 및 탄소나노튜브-페놀수지 복합재료의 계면특성 평가)

  • Wang, Zuo-Jia;Kwon, Dong-Jun;Gu, Ga-Young;Park, Jong-Kyoo;Lee, Woo-Il;Park, Joung-Man
    • Journal of Adhesion and Interface
    • /
    • v.11 no.4
    • /
    • pp.149-154
    • /
    • 2010
  • Interfacial evaluation was investigated for single-carbon fiber/phenolic and carbon nanotube (CNT)-phenolic composites by micromechanical technique and electrical resistance measurement combined with wettability test. Compressive strength of pure phenol and CNT-phenolic composites were compared using Broutman specimen. The contact resistance of CNT-phenolic composites was obtained using a gradient specimen by two and four-point methods. Surface energies and wettability by dynamic contact angle measurement were measured using Wilhelmy plate technique. Since hydrophobic domains are formed as heterogeneous microstructure of CNT in the surface, the dynamic contact angle exhibited more than $90^{\circ}$. CNT-phenolic composites exhibited a higher apparent modulus than neat phenolic case due to better stress transferring effect. Work of adhesion, $W_a$ between single-carbon fiber and CNT-phenolic composites exhibited higher than neat phenolic resin due to the enhanced viscosity by CNT addition. It was consistent with micro-failure patterns in microdroplet test.