• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2248-2253
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• 2005

Although the progress in bipedal walking is impressive in recent years, biped robots still require very high torque and can walk only for a short time interval with their internal batteries. Therefore, further research needs to be carried out to enhance walking efficiency of these robots. In order to achieve this goal, we attempt to imitate human walking with pelvis and waist joint rotations in the frontal plane. In order to investigate the effect of the pelvis and waist joint rotations in the frontal plane motion, we study the frontal plane model with a triangular structure made up of a waist joint and two hip joints. Through simulation, we show that the pelvis rotation can reduce the maximum torque and the control effort, and the waist joint rotation can reduce the trunk sway caused by the pelvis rotation. The combination of these two rotations makes the bipedal walking in the frontal plane more efficient.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.5-8
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• 2001

A three node flat triangular element incorporating Layerwise Zig-Zag Theory(HZZT) is developed suitable for analyzing damped laminated composite structures. Using an interdependent kinematic relation, the higher order shear rotations are replaced by in-plane displacements, a transverse displacement and section rotations, which result in three translations and two rotations. Natural frequencies and modal loss factors of cantilevered laminated plates with embedded damping layers are calculated with the zig-zag triangular element and compared to the experimental results and MSC/NASTRAN results using a layered combination of plate and solid elements.

• Kyungpook Mathematical Journal
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• v.59 no.2
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• pp.277-291
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• 2019

Using the concept of bounded boundary rotation, we investigate various properties of two new generalized classes of spirallike and Robertson functions of complex order with bounded boundary rotations.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.687-702
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• 2012

The objective of this study was to determine crop rotation effects on potato yield, soil chemical and microbiological properties from a short-term field experiment from 2010 to 2011 in Jeju Island, Korea. Potato cropping systems included continuous and rotation sequences of soybean (Glycine max(L.) Merr.), barley (Hordeum vulgare var. hexastichon), rapeseed (Brassica napus L.) and broccoli (Brassica oleracea var. italica). Crop rotations increased the yields of potato from 31% to 52% compared with continuous potato. Marketable yield of potato was highest under soybean plus rapeseed rotation by $20.97MT\;ha^{-1}$ and lowest under continuous cropping by $11.95MT\;ha^{-1}$. The incidence and severity of scab disease was significantly lower in tubers from crop rotation with soybean plus barley. Differences in marketable tuber yields among rotations were associated with potato scab disease. Especially, incidence and severity of potato scab were strongly correlated with soil pH, exchangeable calcium, and bacteria population of the soil. Crop rotations significantly increased soil pH, available phosphate, exchangeable K and Ca, especially in crop rotations with soybean plus barley or rapeseed. Soil microbial biomass C of crop rotations with soybean plus barley or rapeseed, was also significantly higher compared with monoculture. In conclusion, crop rotation may decrease the incidence of soil-born pathogen by increasing soil chemical properties and soil microbial biomass. Overall, potato crop productivity was generally maintained in rotations that contained soybean plus barley or rapeseed but declined under continuous cropping system.

• Smart Structures and Systems
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• v.22 no.3
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• pp.315-326
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• 2018

This paper presents a novel time-domain method for the identification of plastic rotations and stiffness parameters of single-bay frames with nonlinear plastic hinges. Each plastic hinge is modelled as a pseudo-semi-rigid connection with nonlinear hysteretic moment-curvature characteristics at an element end. Through the comparison of the identified end rotations of members that are connected together, the plastic rotation that furnishes information of the locations and plasticity degrees of plastic hinges can be identified. The force consideration of the frame members may be used to relate the stiffness parameters to the elastic rotations and the excitation. The damped-least-squares method and damped-and-weighted-least-squares method are adopted to estimate the stiffness parameters of frames. A noise-removal strategy employing a de-noising technique based on wavelet packets with a smoothing process is used to filter out the noise for the parameter estimation. The numerical examples show that the proposed method can identify the plastic rotations and the stiffness parameters using measurements with reasonable level of noise. The unknown excitation can also be estimated with acceptable accuracy. The advantages and disadvantages of both parameter estimation methods are discussed.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.5
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• pp.703-715
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• 2015

One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1- km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Nino years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.14-20
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• 2011

In mobile ad hoc networks where the communication nodes are moving around, one may perform dynamic routing that can increase the total communication throughput of the network, by determining the ranks of pairs of nodes according to their communication throughput. The balanced Howell rotation is a tournament design scheme for bridge games. This paper explains that the balanced Howell rotation can be applied to enhance the overall communication throughput of mobile ad hoc networks, and proposes and proves the condition under which the balanced Howell rotations may exist.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.108-114
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• 1997

A simple and efficient method is presented for the dynamics of interconnected flexible beams having large rigid body rotations. A simple mass matrix is obtained by interpolating the displacements in the global inertia frame, and the elastic force is also simply computed by using linear finite element technique with the moving frame attached to the beam. For the beams connected by revolute joints, kinematic constraints and relative rotations between the beans are not required and the equations of motions are time integrated by a simple ODE technique. Numerical simulations are conducted to demonstrate the accuracy and efficiency of the present technique.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.7-22
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• 1997

A finite element analysis is performed for lateral buckling problems on the basis of a geometrically nonlinear formulation for a beam with small elastic strain but with possibly large rotations. The total Lagrangian formulation for a general large deformation, which involves finite rotations, is chosen and the exponential map is used to treat finite rotations from the Eulerian point of view. For lateral buckling, the point of vanishing determinant of the resulting unsymmetric tangent stiffness is traced to examine its relationship to bifurcation points. It is found that the points of vanishing determinant is not corresponding to bifurcation points for large deformations in general, which suggests that the present unsymmetric tangent stiffness is not an exact first derivative of internal forces with respect to displacement. This is illustrated through several numerical examples and followed by appropriate discussion.

• Transactions of Materials Processing
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• v.5 no.4
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• pp.320-326
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• 1996

Based upon experimental observations the authors have shown in the previous studies that the orientations of orthotropy axes of anisotropic sheet metals are subjected to change during tensile loading at angles to the rolling direction. To predict the rotations of orthotropy axes under general plane stress conditions, a simple phenomenological model is proposed which accounts for the effect of work hardening. Predictions from the model are compared against the experiments for 0%, 3%, and 6% of 1st tensile prestrains in the rolling direction and 2nd tensile prestrains at 30$^{\circ}$, 45$^{\circ}$ and 60$^{\circ}$ to the 1st prestrains axis. The model showed good agreements with the experimental observations. A new interpretation of the experimental data is suggested regarding the rotations of orthotropy axes.