• 제목/요약/키워드: energy formula

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Using Chemical and Biological Approaches to Predict Energy Values of Selected Forages Affected by Variety and Maturity Stage: Comparison of Three Approaches

  • Yu, P.;Christensen, D.A.;McKinnon, J.J.;Soita, H.W.
    • Asian-Australasian Journal of Animal Sciences
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    • 제17권2호
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    • pp.228-236
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    • 2004
  • Two varieties of alfalfa (Medicago sativa L cv. Pioneer and Beaver) and timothy (Phleum pratense L cv. Climax and Joliette), grown at different locations in Saskatchewan (Canada), were cut at three stages [1=one week before commercial cut (early bud for alfalfa; joint for timothy); 2=at commercial cut (late bud for alfalfa; pre-bloom head for timothy); 3=one week after commercial cut (early bloom for alfalfa; full head for timothy)]. The energy values of forages were determined using three approaches, including chemical (NRC 2001 formula) and biological approaches (standard in vitro and in situ assay). The objectives of this study were to determine the effects of forage variety and stage of maturity on energy values under the climate conditions of western Canada, and to investigate relationship between chemical (NRC 2001 formula) approach and biological approaches (in vitro and in situ assay) on prediction of energy values. The results showed that, in general, forage species (alfalfa vs. timothy) and cutting stage had profound impacts, but the varieties within each species (Pioneer vs. Beaver in alfalfa; Climax vs. Joliette in timothy) had minimal effects on energy values. As forage maturity increased, the energy contents behaved in a quadratic fashion, increasing at stage 2 and then significantly decreasing at stage 3. However, the prediction methods-chemical approach (NRC 2001 formula) and biological approaches (in vitro and in situ assay) had great influences on energy values. The highest predicted energy values were found by using the in situ approach, the lowest prediction value by using the NRC 2001 formula, and the intermediate values by the in vitro approach. The in situ results may be most accurate because it is closest to simulate animal condition. The energy values measured by biological approaches are not predictable by the chemical approach in this study, indicating that a refinement is needed in accurately predicting energy values.

항타공식의 신뢰도 (Reliability of Pile Driving Formula)

  • 박영호;김경석
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 1999년도 봄 학술발표회 논문집
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    • pp.209-216
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    • 1999
  • Prefabricated piles used for construction of highway bridges are most of steel pipe piles and few of prestressed concrete piles. Its installation and inspection are less controllable and have much uncertainty due to changes in subsoil and groundwater conditions. However, most of these piles have been controlled using outdated pile driving formula such as Hiley's formula which models just the energy conservation due to its simple applicability in the field. This formula results in overstriking or sometimes understocking due to buckling of pile head. Engineers cannot ensure by the formula whether pile is installed properly. To compensate the drawbacks of excising pile formula, parameters in Hiley's formula and 55 formula are reviewed. Final sets used in pile formula and PDA test results(E.O.I.D) are measured during pile driving along the depth. These measured results along the depth were compared with each other and with N values, so that relations between the each result could be inferred. Also the factor of safety which can be used for pile driving formula are suggested.

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ANALYSIS OF UNCERTAINTY QUANTIFICATION METHOD BY COMPARING MONTE-CARLO METHOD AND WILKS' FORMULA

  • Lee, Seung Wook;Chung, Bub Dong;Bang, Young-Seok;Bae, Sung Won
    • Nuclear Engineering and Technology
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    • 제46권4호
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    • pp.481-488
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    • 2014
  • An analysis of the uncertainty quantification related to LBLOCA using the Monte-Carlo calculation has been performed and compared with the tolerance level determined by the Wilks' formula. The uncertainty range and distribution of each input parameter associated with the LOCA phenomena were determined based on previous PIRT results and documentation during the BEMUSE project. Calulations were conducted on 3,500 cases within a 2-week CPU time on a 14-PC cluster system. The Monte-Carlo exercise shows that the 95% upper limit PCT value can be obtained well, with a 95% confidence level using the Wilks' formula, although we have to endure a 5% risk of PCT under-prediction. The results also show that the statistical fluctuation of the limit value using Wilks' first-order is as large as the uncertainty value itself. It is therefore desirable to increase the order of the Wilks' formula to be higher than the second-order to estimate the reliable safety margin of the design features. It is also shown that, with its ever increasing computational capability, the Monte-Carlo method is accessible for a nuclear power plant safety analysis within a realistic time frame.

제로터 유압 모터의 용량에 관한 연구 (An Analysis on Volumetric Displacement of Hydraulic Gerotor Motor)

  • 김대명;함영복;김성동
    • 유공압시스템학회:학술대회논문집
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    • 유공압시스템학회 2010년도 춘계학술대회
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    • pp.39-43
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    • 2010
  • It is hard and complex to analytically derive a volumetric displacement formula of a gerotor hydraulic motor because geometric shape of its rotors is complicate. An analytical method about the volumetric displacement is proposed in this work, which is relatively easy and based upon two physical concepts. The first one is energy conservation between hydraulic input energy of the motor and mechanical output energy. The second concept is torque equilibrium with respect to inner and outer rotors. The proposed formula about the volumetric displacement is verified by comparing an analytical displacement and a numerical displacement for an example specification of the motor. The numerical displacement is calculated through a kind of CAD technology. The analytical formula can be utilized in analysis and design of hydraulic gerotor motors.

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Evapotranspiration Estimation Study Based on Coupled Water-energy Balance Theory in River Basin

  • Xue, Lijun;Kim, JooCheol;Li, Hongyan;Jung, Kwansue
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2018년도 학술발표회
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    • pp.146-146
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    • 2018
  • Basin evapotranspiration is the result of water balance and energy balance, which is affected by climate and underlying surface characteristics, the process is complex, and spatial and temporal variability is large, the evapotranspiration estimation of river basin is an important but difficult problem in the field of hydrology, over the years, many scholars devoted to the basin actual evapotranspiration estimation and achieved excellent results. We discuss Budyko coupled water-energy balance theory and evaporation paradox, then use the Fu's equation to estimate actual evapotranspiration yearly in different areas with different dryness. The result shows that Fu's equation has high precision for estimating evapotranspiration yearly in our selected study area, and the estimation result has higher precision in the area with high dryness. Then, we propose an improved formula which can be used to estimate actual evapotranspiration monthly. Furthermore, we found that the parameter in the formula reflects general conditions of underlying surface and it is affected by several factors, at last, we tried to propose the calculation formula. The study indicates that Fu's equation provides a reliable method for evapotranspiration estimation in dry regions as well as semi-humid and semi-arid regions, which has great significance for forecasting river basin water resources and inquiring into ecological water requirement.

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A Study on the Dissipation Energy of Plate due to Cutting

  • Lee, J. W.;Hong, S. J.
    • Journal of Ship and Ocean Technology
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    • 제1권1호
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    • pp.48-56
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    • 1997
  • This paper deals with the energy dissipation of ductile metal plate due to cutting. By using nondimensional analysis, we present that the dissipation energy of tearing behaviour can be formulated as a function of slenderness ratio expressed by cutting length, yield stress, plate thickness and elastic modulus. The validity of the proposed formula for Al-alloy, copper and mild steel is demonstrated by comparing the proposed formula with experimental results, which are shown in good agreements except for thick mild steel plate.

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유압 하이브리드 구동 시스템의 축압기 용량 설계 (Capacity Design of Accumulator in Hydraulic Hybrid Drive Brake System)

  • 이재구;김정현;김성동
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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    • pp.15-21
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    • 2001
  • An accumulator in hydraulic systems stores kinetic energy during braking action, and then that controls hasty surge pressure. An energy recovery system using accumulator seems to be advantageous for ERBS due to its high energy density. This study suggests a method to decide suitable accumulator volume for ERBS. The method is based upon energy conservation between kinetic energy of moving inertia and elastic energy of accumulator. The energy conversion was analyzed and a simple formula was derived. A series of computer simulation was done to verify effectiveness of the formula. The results of the simulation work were compared with those of experiments and these results show that the proposed design is effective for decision accumulator volume in ERBS.

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진사탁(陳士鐸)의 『변증록(辨證錄)』 처방(處方) 연구(硏究) - 비증(痹症)을 중심으로 - (Study on Bi-jeung Prescriptions in Byunjeungrok)

  • 성시열;국윤범
    • 대한한의학방제학회지
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    • 제22권1호
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    • pp.47-64
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    • 2014
  • Objectives : Bi-jeung is a traditional oriental medical name. Bi-jeung is similar to rheumatoid arthritis(RA). This study was investigated to get the practical use of Bi-jeung prescriptions in Byunjeungrok. Methods: Original records related Bi-jeung in Byunjeungrok are interpreted and contemplated. Results: Bi-jeung prescriptions in Byunjeungrok are put stress on Byunjeung in conformity with entrails good energy enforcing as well as evil energy eliminating removing damp-evil among wind-evil cold-evil and damp-evil showing concrete prognosis. Conclusions: This study indicates that Bi-jeung prescriptions in Byunjeungrok have an influences for RA. It may also suggest that Bi-jeung prescriptions may expand therapy field for treatment of RA. and its complications.

강판으로 보강된 비좌굴가새의 성능에 대한 해석적 연구 (An Analytical Study on the Performance of Buckling Restrained Brace Reinforced with Steel Plate)

  • 김대홍;김혁수;유정한
    • 한국공간구조학회논문집
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    • 제22권1호
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    • pp.51-57
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    • 2022
  • In this paper, based on the finite element analysis model verified in previous studies, a new model of a buckling restrained brace reinforced with a steel plate was proposed. A design formula was proposed for the new model to dissipate energy without buckling the steel core under load protocol, and the performance of the model satisfying the design formula was evaluated by comparing it with the previous model through the results of hysteresis loop, bi-linear curve, cumulative energy dissipation capacity, and equivalent viscous damping.

A MONOTONICITY FORMULA AND A LIOUVILLE TYPE THEOREM OF V-HARMONIC MAPS

  • Zhao, Guangwen
    • 대한수학회보
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    • 제56권5호
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    • pp.1327-1340
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    • 2019
  • We establish a monotonicity formula of V-harmonic maps by using the stress-energy tensor. Use the monotonicity formula, we can derive a Liouville type theorem for V-harmonic maps. As applications, we also obtain monotonicity and constancy of Weyl harmonic maps from conformal manifolds to Riemannian manifolds and ${\pm}holomorphic$ maps between almost Hermitian manifolds. Finally, a constant boundary-value problem of V-harmonic maps is considered.