약간 과압밀된 점성토에서 발생하는 피에조콘 지연소산 메커니즘

하태균,정종홍,김홍종,박래선,정충기 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.10

For standard piezocones with shoulder filter elements immediately behind the cone tip, general dissipation curves show monotonically decreasing pore pressure from the initial value. However, dilatory dissipation behavior, showing a temporary increase in pore pressure followed by a decrease in the hydrostatic pressure, has been observed in lightly overconsolidated cohesive soils (1<OCR≤4). This unusual dissipation behavior was reported mostly in heavily overconsolidated ground and previous researches were limited to such cases. In this study, the mechanism of dilatory dissipation in lightly overconsolidated cohesive soils was investigated. The relativities of the ground properties evaluated from the CPTu data to the dilatory dissipation were analyzed. And, finite difference analyses on dissipation after cone penetration were performed. It was found that dilatory dissipation occurs in lightly overconsolidated soils since the higher excess pore pressure at the cone face propagates upward to the shoulder filter. Also, it was shown that the ratio of initial excess pore pressure at the cone face to that of the shoulder filter (u1i/u2i), which is related to overconsolidation ratio (OCR) and hydrostatic pressure (u0), affects the dilatory dissipation.

Effect of the sagittal ankle angle at initial contact on energy dissipation in the lower extremity joints during a single-leg landing

Lee, Jinkyu,Song, Yongnam,Shin, Choongsoo S. Elsevier 2018 GAIT AND POSTURE Vol.62 No.-

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>During landing, the ankle angle at initial contact (IC) exhibits relatively wide individual variation compared to the knee and hip angles. However, little is known about the effect of different IC ankle angles on energy dissipation.</P> <P><B>Research question</B></P> <P>The purpose of this study was to investigate the relationship between individual ankle angles at IC and energy dissipation in the lower extremity joints.</P> <P><B>Methods</B></P> <P>Twenty-seven adults performed single-leg landings from a 0.3-m height. Kinetics and kinematics of the lower extremity joints were measured. The relationship between ankle angles at IC and negative work, range of motion, the time to peak ground reaction force, and peak loading rate were analyzed.</P> <P><B>Results</B></P> <P>The ankle angle at IC was positively correlated with ankle negative work (r = 0.80, R<SUP>2</SUP> = 0.64, <I>p <</I> 0.001) and the contribution of the ankle to total (ankle, knee and hip joint) negative work (r = 0.84, R<SUP>2</SUP> = 0.70, p < 0.001), but the ankle angle was negatively correlated with hip negative work (r = −0.46, R<SUP>2</SUP> = 0.21, <I>p</I> = 0.01) and the contribution of the hip to total negative work (r = −0.61, R<SUP>2</SUP> = 0.37, <I>p <</I> 0.001). The knee negative work and the contribution of the knee to total negative work were not correlated with the ankle angle at IC. The ankle angle at IC was positively correlated with total negative work (r = 0.50, R<SUP>2</SUP> = 0.25, <I>p < </I>0.01) and negatively correlated with the peak loading rate (r = −0.76, R<SUP>2</SUP> = 0.57, <I>p </I>< 0.001).</P> <P><B>Significance</B></P> <P>These results indicated that landing mechanics changed as the ankle angle at IC increased, such that the ankle energy dissipation increased and redistributed the energy dissipation in the ankle and hip joints. Further, these results suggest that increased ankle energy dissipation with a higher IC plantar flexion angle may be a potential landing technique for reducing the risk of injury to the anterior cruciate ligament and hip musculature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ankle angle at initial contact (IC) alter energy dissipation of lower limb joints. </LI> <LI> Higher plantar flexion at IC increases ankle energy dissipation during landing. </LI> <LI> Higher plantar flexion at IC decreases hip energy dissipation during landing. </LI> <LI> Higher plantar flexion at IC decreases peak loading (GRF) rates. </LI> <LI> Higher plantar flexion at IC may reduce injury risk to the ACL and hip musculature. </LI> </UL> </P>

전력소비 최소화를 위한 새로운 펑션유닛의 자원 할당 알고리듬

인치호,Lin, Chi-Ho 한국전기전자학회 2004 전기전자학회논문지 Vol.8 No.2

본 논문에서는 산술 연산을 수행하는 연산자의 수가 많은 펑션유닛의 입력 데이터의 스위칭을 최소화하여 소비 전력을 줄인다. 따라서 회로전체의 전력 소모를 줄이기 위해 연산자가 소모하는 전력을 우선적으로 최소화하는 것은 전력 감소의 큰 효과를 가진다. 본 논문은 VLSI회로에서 전력소비에 가장 영향을 많이 미치는 펑션유닛의 연산과정에서 소비하는 전력을 최소화하는 알고리즘을 제안한다. 펑션유닛에서 모든 연산은 전력소비 정보를 가진 전력 라이브러리를 이용하여 피연산자를 스케줄링한다. 전력 라이브러리는 펑션유닛의 모든 입력에 대해 각각의 컨트롤 스텝마다 입력 데이터의 정보를 갱신하고, 그 정보는 스케줄링 과정에서 사용되어진다. 따라서 모든 연산에서 최적화된 데이터를 펑션유닛의 입력으로 하여 전력소비를 최소화 할 수 있다. 본 논문은 상위 레벨 합성 과정에서 펑션유닛에 대한 최소의 전력소비를 위하여 제안하는 알고리즘을 적용하여 실험한 결과 최대 9.4%의 전력 감소효과가 있었다. This paper reduces power dissipation with the minimum switching activity of functional units that have many operators. Therefore, it has more effects of power dissipation that operator dissipation to reduce power dissipation of whole circuit preferentially. This paper proposes an algorithm that minimize power dissipation in functional units operations that affect much as power dissipation in VLSI circuit. The algorithm has scheduled operands using power library that has information of all operands. The power library upgrades information of input data in each control step about all inputs of functional units and the information is used at scheduling process. Therefore, the power dissipation is minimized by functional units inputs in optimized data. This paper has applied algorithm that proposed for minimizing power dissipation to functional unit in high level synthesis. The result of experiment has effect of maximum 9.4 % for minimizing power dissipation.

Dissipation of energy in steel frames with PR connections

Reyes-Salazar, Alfredo,Haldar, Achintya Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.9 No.3

The major sources of energy dissipation in steel frames with partially restrained (PR) connections are evaluated. Available experimental results are used to verify the mathematical model used in this study. The verified model is then used to quantify the energy dissipation in PR connections due to hysteretic behavior, due to viscous damping and at plastic hinges if they are formed. Observations are made for two load conditions: a sinusoidal load applied at the top of the frame, and a sinusoidal ground acceleration applied at the base of the frame representing a seismic loading condition. This analytical study confirms the general behavior, observed during experimental investigations, that PR connections reduce the overall stiffness of frames, but add a major source of energy dissipation. As the connections become stiffer, the contribution of PR connections in dissipating energy becomes less significant. A connection with a T ratio (representing its stiffness) of at least 0.9 should not be considered as fully restrained as is commonly assumed, since the energy dissipation characteristics are different. The flexibility of PR connections alters the fundamental frequency of the frame. Depending on the situation, it may bring the frame closer to or further from the resonance condition. If the frame approaches the resonance condition, the effect of damping is expected to be very important. However, if the frame moves away from the resonance condition, the energy dissipation at the PR connections is expected to be significant with an increase in the deformation of the frame, particularly for low damping values. For low damping values, the dissipation of energy at plastic hinges is comparable to that due to viscous damping, and increases as the frame approaches failure. For the range of parameters considered in this study, the energy dissipations at the PR connections and at the plastic hinges are of the same order of magnitude. The study quantitatively confirms the general observations made in experimental investigations for steel frames with PR connections; however, proper consideration of the stiffness of PR connections and other dynamic properties is essential in predicting the dynamic behavior.

Energy Dissipation Characteristics Modelling for Hot Extrusion Forming of Aluminum-Alloy Components

Hongcheng Li,Yuanjie Wu,Huajun Cao,Feng Lu,Congbo Li 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.6

The hot extrusion forming process is widely used to process aluminum-alloy components in both the automobile and aircraft manufacturing industries. Since it involves pushing the material through the die at increased temperature, it is very energy-intensive despite requiring less blank material allowance. During hot extrusion forming, the multi-stage dynamic conversion of electricity, mechanical energy, and hydraulic energy to heat results in high energy dissipation. In order to improve the power and energy conversion efficiency of hot extrusion forming process, it is necessary to identify the energy dissipation characteristics. The transfer and conversion paths of the electrical, mechanical, and hydraulic energy from the motor to the hydraulic cylinder were firstly depicted based on the motion cycle of the extruder. A bond graph-based energy dissipation model was then proposed for dynamically identifying the energy-saving potentials. The energy dissipation model integrated the power bond graph sub-model of energy conversion elements such as motor, pump, hydraulic valve group, and hydraulic cylinder. These power bond graph sub-models were separately developed to find the energy dissipation state equations of energy conversion elements. An experiment was carried out using data obtained from the energy management system to validate the bond graph-based energy dissipation model. The results have shown that the power and energy conversion efficiency of hot extrusion forming is primarily controlled by the parameters such as extrusion velocity and extrusion force. Both the higher extrusion velocity and lower extrusion force will reduce the power and energy conversion efficiency. An optimal combination of extrusion velocity and pressure can achieve the lowest energy consumption per unit product.

Study of the Energy Dissipation over the Type-A Piano Key Weir

Deepak Singh,Munendra Kumar 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

This study assesses the effects of geometrical variations, i.e., relative width ratio, magnification ratio, and cyclic variation, on the Piano Key Weir energy dissipation performance. In order to assess this, 12 type-A PKW models were tested by conducting an experimental investigation. The analysisincludes results from 280 tests and comprehensive findings of the fluid domain. The results demonstrated that the configuration of the PKWs has a greater influence on energy dissipation. The present study’s findings show that the type-A PKW dissipates energy more efficiently than nonlinear or standard weirs. The energy loss over the PKW decreases as the magnification and relative width ratios increase, although the energy dissipation increases with key cycle numbers. Furthermore, the sensitivity analysis of the weir was examined by making steps at outlet key floors and found that the energy dissipation has been increased by 6.67% at low heads while reduced by 1.59% at higher heads. In addition, the author proposed two empirical projection equations for the optimal relative residual energy configuration downstream of the PKW. The proposed equations are the function of headwater ratio, relative width ratio, and magnification ratio. The results of this investigation are in perfect correlation with earlier studies.

Viscous dissipation effect on heat transfer characteristics of mixed electromagnetic/pressure driven liquid flows inside micropumps

Mostafa Shojaeian,Seyyed Mohammad Nima Shojaee 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.4

This paper presents the effect of viscous dissipation on heat transfer characteristics of mixed electromagnetic/pressure driven liquid slip flows inside parallel plate microchannels. Flow is governed by the Navier-Stokes equations subject to the imposition of electromagnetic field with the boundary condition appropriate to the slip flow regime. For isoflux walls, some closed form expressions for the local and bulk temperature profiles and the Nusselt number in terms of dimensionless slip length, Hartmann number and Brinkman number are given, while the viscous dissipation is also taken into account. Then the analytical solutions derived in this analysis are elaborated. It turns out that since the contribution of the viscous dissipation on the Nusselt number under the given circumstances, especially a stronger electromagnetic field, may reach to nearly 10%, therefore, the viscous heating should be taken into consideration. Otherwise,the heat transfer rate may be overestimated or underestimated depending on whether the fluid is being heated or cooled. Also, there are singularities in Nusselt number values, which move close together by including the viscous dissipation. Further, an increase in the Hartmann number increases the convection, which is especially reflected in smaller values of dimensionless slip length.

상환 원칙은 지대소진을 증가시키는가?

박성훈(Sung-Hoon Park) 한국산업경제학회 2016 한국산업경제학회 정기학술발표대회 논문집 Vol.2016 No.5

본 연구는 소송에 준법의 정도를 반영한 상환 원칙이 적용되는 경우에 지대소진이 증가하는지에 대해 분석한다. 이를 위해 상환 원칙이 적용된 소송과 적용되지 않은 소송을 고려한 두 경합을 소개하고, 두 경합으로부터 내쉬균형과 지대소진을 도출한다. 본 연구는 소송당사자들의 ‘준법의 정도’이 차이가 나는 경우에 상환 원칙의 채택으로 지대소진이 감소될 수 있음을 보인다. We analyse whether reimbursement rule that is proportional to the degree of fault incurs the increase in rent dissipation. To do so, we introduce two rent-seeking contests: a litigation with reimbursement rule and a litigation with non-reimbursement rule. Then, we obtain equilibrium legal effort and rent dissipation for two contests. Comparing two rent dissipation, we show that if the discrepancy in the degree of fault for litigants is sufficiently large, reimbursement rule may reduce rent dissipation in litigation.

전단핀칭이 발생한 철근콘크리트 보의 에너지소산능력 평가

엄태성(Eom Tae-Sung),박홍근(Park Hong-Gun) 대한건축학회 2008 大韓建築學會論文集 : 構造系 Vol.24 No.8

For reliable performance evaluation and design of buildings against earthquakes, energy dissipation capacity of structures and their members should be accurately estimated. In the present study, nonlinear analysis was performed for the slender reinforced concrete beam showing pinching under cyclic loading by using the nonlinear truss model, and the behavioral characteristics and mechanism of energy dissipation were investigated. The results showed that the energy dissipation of the beam is developed due to flexural deformation and the longitudinal reinforcing bars at the ends of the cross-section that develop large plastic strains due to the flexural deformation during cyclic loading, mainly contribute to the energy dissipation. Based on the results, a simplified method for predicting the energy dissipation of slender reinforced concrete beams was developed. For verification, the proposed method was applied to slender beams with different design parameters and the predicted energy dissipation capacities were compared with test results.

Steel dual-ring dampers: Micro-finite element modelling and validation of cyclic behavior

Mahdi Usefvand,Ali Mohammad Rousta,Mojtaba Gorji Azandariani,Hamid Abdolmaleki 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.4

Extensive studies have been performed by researchers to increase the ductility and energy-absorption of concentrically braced frames. One of the most widely used strategies for increasing ductility and energy-absorbing is the utilization of energy-dissipation systems. In this regard, the energy-dissipation system consisting of a steel dual-ring damper (SDRD) with different construction details is presented, to improve hysteresis behavior and performance of steel ring dampers (SRD). The most important cause of energy-dissipation in SRDs are the development of bending plastic hinges in the rings. Therefore, by adding an inner ring to the SDR system, it increases the number of moment plastic hinges and in turn increases energy dissipation. Parametric studies havse been performed applying the nonlinear micro-finite element (MFE) procedure to investigate the improved models. The parametric studies comprise examining the efficacy of thickness parameters and the inner ring diameters of the improved models. The SRD models was selected as the base model for comparing and evaluating the effects of improved dampers. MFE models were then analyzed under cyclic loading and nonlinear static methods. Confirmation of the results of the MFE models were performed against the test results. The results indicated that the diameter to the thickness ratio of inner ring of SDRDs has a considerable influence on determining the hysteresis behavior, ductility, ultimate capacity and performance, as well as energy dissipation. Also, the results show that the details of the construction of the internal and external ring connections were a considerable effect on the performance and hysteresis behavior of SDRDs.