• Title/Summary/Keyword: G-force

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Advances in measuring linear viscoelastic properties using novel deformation geometries and Fourier transform techniques

  • See, Howard
    • Korea-Australia Rheology Journal
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    • v.13 no.2
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    • pp.67-81
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    • 2001
  • The development of new techniques for the dynamic measurement of linear viscoelastic properties is an active area of rheometry, and this paper surveys some novel deformation geometries which have been recently reported e.g. oscillating probe-type devices which are imbedded in or placed on the surface of the sample. Small amplitude band-limited pseudorandom noise is used for the displacement signal, with Fourier analysis of the complex waveform of the resistance force yielding the frequency dependent viscoelastic material functions (e.g. storage and loss moduli G", G"). Theoretical calculations of the fundamental equations relating force to displacement and instrument geometry, were carried out with the aid of the correspondence principle of linear viscoelasticity. The rapidity of the tests and flexibility in terms of sample preparation and stiffness mean that this basic technique should find many applications in rheometry. Three examples of oscillatory tests are presented in detail squeeze flow, imbedded needle and concentric sliding cylinder geometries.eometries.

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An Analytical Study on Ductility of Reinforced Concrete Columns under Tension Controlled Region (인장지배영역에서의 철근콘크리드 기둥의 연성에 관한 해석적 연구)

  • 손혁수;김준범;이재훈
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.10a
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    • pp.527-532
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    • 1997
  • Design strength of structural members could be determined by applying a strength reduction factor to nominal strength. At the beginning point of the transition region for the strength reduction factor, P=0.1$\sigma$$_{ck}A_g$, only sectional area and concrete strength are adopted as the variables of P=0.1$\sigma$$_{ck}A_g$. Therefore, P=0.1$\sigma$$_{ck}A_g$ is the empirically adopted which does not consider steel ratio, steel yielding stress, and steel arrangement. So, this research was perpormed the computer program for the analysis of axial force-moment-curvature relationship of reinforced concrete columns by sectional behaviour nonlinear analysis using a concrete compressive stress-strain curve, in order to investigate the ductility of reinforced concrete columns. As a result, ductility indicies of axial force, P=0.1$\sigma$$_{ck}A_g$, represented the lack of consistency of the indicies value for the various sections.

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Modeling dynamic interactions between the support foot and the ground in bipedal walking

  • Jung, Moon-Ryul
    • Journal of the Korea Computer Graphics Society
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    • v.1 no.2
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    • pp.201-212
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    • 1995
  • This paper presents a new method of dynamics-based synthesis of bipedal, especially human, walking. The motion of the body at a time point is determined by ground reaction force and torque under the support foot and joint torques of the body at that time point. Motion synthesis involves specifying conditions that constrain ground reaction force and torque, and joint torques so that a given desired motion may be achieved. There are conditions on a desired motion which end-users can think of easily, e.g. the goal position and orientation of the swing foot for a single step and the time period of a single step. In this paper, we specify constraints on the motion of the support foot, which end-users would find difficult to specify. They are constraints which enforce non-sliding, non-falling, and non-spinning the support foot. They are specified in terms of joint torques and ground reaction force and torque. To satisfy them, both joint torques and ground reaction force and torque should be determined appropriately. The constraints on the support foot themselves do not give any good clues as to how to determine ground reaction force and torque. For that purpose, we specify desired trajectories of the application point of vertical ground reaction force (ground pressure) and the application point of horizontal ground reaction (friction) force. The application points of vertical pressure and friction force are good control variables, because they are indicators to kinds of walking motions to synthesize. The synthesis of a bipedal walking motion, then, consists of finding a trajectory of joint torques to achieve a given desired motion, so that the constraints are satisfied under the condition of the prescribed center of pressure and center of friction. Our approach is distinguished from many other approaches, e.g. the inverted-pendulum approach, in that it captures and formulates dynamics of the support foot and reasonable constraints on it.

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Relationship among Sales-force Control System, Salesperson's Job Attitudes, and Performance in Hotel (호텔에서의 영업력 관리시스템과 직무태도, 성과와의 영향관계)

  • Kim, Pan-Young;Song, Sung-In
    • The Journal of the Korea Contents Association
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    • v.8 no.7
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    • pp.233-242
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    • 2008
  • Sales-force management practices(e.g., selection, training, rewards, evaluation) constitute a crucial aspect of the sales force control system, as they influence on the salesperson's role ambiguity, satisfaction and performance. But it is difficult to find studies on the effects of hotel's sales force control system. So, we studied about this subject more deeply. The purpose of our research is to examine important relationships among sales force control system(e.g., sales territory design, training, reward, training, supervisor's support), job attitudes(satisfaction and role ambiguity), and sales force performance. A conceptual model is presented and hypotheses are developed. This study contributes to sales management research of hotel sales person in some important ways. This study offers new insights both to sales practitioners and researchers. First, this study introduces a new approaching method for developing new model of hotel sales-force research. Second, in the practical implications, managers should take actions as like an encouragement, direction, monitering, and education of sales know-how to reduce the employee's role ambiguity and to improve job satisfaction and sales performance.

Probing α/β Balances in Modified Amber Force Fields from a Molecular Dynamics Study on a ββα Model Protein (1FSD)

  • Yang, Changwon;Kim, Eunae;Pak, Youngshang
    • Bulletin of the Korean Chemical Society
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    • v.35 no.6
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    • pp.1713-1719
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    • 2014
  • 1FSD is a 28-residue designed protein with a ${\beta}{\beta}{\alpha}$ motif. Since this protein displays most essential features of protein structures in such a small size, this model protein can be an outstanding system for evaluating the balance in the propensity of the secondary structures and the quality of all-atom protein force fields. Particularly, this protein would be difficult to fold to its correct native structure without establishing proper balances between the secondary structure elements in all-atom energy functions. In this work, a series of the recently optimized five amber protein force fields [$ff03^*$, $f99sb^*$-ildn, ff99sb-${\phi}^{\prime}$-ildn, ff99sb-nmr1-ildn, ff99sb-${\Phi}{\Psi}$(G24, CS)-ildn] were investigated for the simulations of 1FSD using a conventional molecular dynamics (MD) and a biased-exchange meta-dynamics (BEMD) methods. Among those tested force fields, we found that ff99sb-nmr1-ildn and ff99sb-${\Phi}{\Psi}$(G24, CS)-ildn are promising in that both force fields can locate the native state of 1FSD with a high accuracy (backbone rmsd ${\leq}1.7{\AA}$) in the global free energy minimum basin with a reasonable energetics conforming to a previous circular dichroism (CD) experiment. Furthermore, both force fields led to a common set of two distinct folding pathways with a heterogeneous nature of the transition state to the folding. We anticipate that these force fields are reasonably well balanced, thereby transferable to many other protein folds.

Variation and Correlation of Shearing Force with Feed Nutritional Characteristics of Wheat Straw

  • Cui, X.M.;Yang, Z.B.;Yang, W.R.;Jiang, S.Z.;Zhang, G.G.;Liu, L.;Wu, B.R.;Wang, Z.F.
    • Asian-Australasian Journal of Animal Sciences
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    • v.26 no.10
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    • pp.1466-1473
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    • 2013
  • This experiment was conducted to study the variation laws and correlations of shearing force and feed characteristics including morphological characteristic, chemical composition and in situ degradability of wheat straw. Feasibility of evaluating the nutritional value of wheat straws with shearing force values was analyzed in this study. Six hundred wheat straw plants (Jimai 22) were randomly selected and placed in a cool and ventilated place. Samples were collected in the 1st, 15th, 30th, 45th, 60th d after harvest to measure shearing force, morphological characteristic, nutritional composition. Rumen degradation of dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of wheat straws were determined by the nylon bags method. The results demonstrated that linear and quadratic effects of storage time on all the tested morphological characteristics were significantly correlative (p<0.01). As storage time goes on, all the tested nutrients and their rumen degradations of wheat straw was linearly (p<0.01) and quadratic (p<0.01) correlative except ADF content and rumen degradation of ADF. Significant correlations were determined in linear effect of shearing force on morphological characteristics (p<0.01), and linear density and diameter were a more sensitive predictor than stem thickness for shearing force. There were strong correlations between storage time and all the measured physical characteristics (shearing force, morphological characteristics and shearing force standardized by morphological characteristics) (p<0.01). Nutrition compositions were linearly correlative with shearing force and standardized shearing force (p<0.01). The linear correlation between rumen degradation of DM and NDF and shearing force and standardized shearing force were evident (p<0.01). In conclusion, shearing force, nutrition compositions and their rumen degradation of wheat straw were still dynamic with storage time after harvest. Correlation could be found between shearing force and nutritional characteristics of wheat straw. Nutrient content, morphological index and rumen degradation of DM and NDF could be predicted by changes in shearing force. Shearing force should be applied according to a standardized storage time when it is used to forecast the feed value of wheat straws.

An Experimental Analysis on the Stewart Platform-Based 6 Axis Force-Torque Sensor (Stewart Platform 방시그이 6축 힘-토크 센서에 관한 실험적 해석)

  • Han, J.H.;Kang, C.G.
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.1
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    • pp.78-83
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    • 1997
  • The paper presents the experimental analysis of a Stewart platform-based force-torque senor. The closed-form solution of forward kinematics of the Stewart platform is derived approximately by way of a linearization technique, and the solution is used in the force analysis of the force-torque sensor. An exper- mental studies show that the proposed method including gravity compensation algorithm is valid for Stew- art platform-based force-torque sensors. The performance of the developed force-torque sensor is evaluated in view of accuracy and linearity in measurements.

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Effect of Oyster Mushrooms on Meat Tenderization (느타리버섯이 육류의 연육에 미치는 효과)

  • Chung, Koo-Min;An, Hui-Jeong
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.41 no.6
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    • pp.829-833
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    • 2012
  • To investigate the effects of oyster mushrooms (Pleurotus ostreatus) on beef and pork tenderization, freezedried mushroom (whole, cap, and stem) powder and mushroom extracts were prepared. Both fresh and boiled beef and pork had mushroom power and extract powders spread on them, and let sit for 30 minutes at room temperature. After that, the hardness and amino nitrogen content of the meats were measured. The hardness of the meat decreased by about 20%~35% after spreading. Also, the amino nitrogen contents increased due to the effect of protease in the mushrooms. The effects were greater in raw beef. The mushrooms showed almost the same effects regardless of which part of the mushrooms were used (whole, cap, and stem).

Proposing the Shear Force Equation of GFRP Strengthened Masonry Wall (유리섬유로 보강한 조적벽체의 전단내력식 설정에 관한 연구)

  • Kwon, Ki-Hyuk;Lee, Soo-Chul;Jung, Won-Chul
    • Journal of the Korean Society of Hazard Mitigation
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    • v.7 no.1 s.24
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    • pp.1-9
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    • 2007
  • This study does by purpose that propose shear resisting force equation of reinforced masonry wall that is reinforced by GFRP(glass fiber reinforced polymer) based on result that is noted through cyclic loading of masonry wall and a shaking table experiment of mock that reflect identifying marks of masonry building which is constructed in domestic. It was Rocking mode to dominate failure of masonry wall in the experiment results, and the equations of UBC show the most resemblant value with experiment results. Through this study, propose the shear force equation of GFRP strengthened masonry wall as following. $$V_n=0.02A_n{\sqrt{f'_m}}+0.022b_gh_g(1+2{\alpha})^3{\sqrt{f_g}}(N/mm^2)$$.