• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.547-553
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• 2004

A hemispherical asperity moving over a flat plane is simulated based on classical molecular dynamics. The asperity and the plane consist of silicon atoms whose interactions are governed by the Tersoff three-body potential. The gap between the asperity and the plane is maintained to produce attractive normal force in order to investigate the adhesive friction and wear. The simulation focuses on the influence of crystallographic orientation of the contacting surfaces and the moving direction. It is demonstrated that the adhesive friction and wear are lower when crystallographic orientations of the contacting surfaces are different, and also depend on the moving direction relative to the crystal1ographic orientation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.8
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• pp.559-564
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• 2009

The variation in the shape of water droplet moving on atomistically smooth solid surface in the presence of a constant body force is simulated using molecular dynamics simulation. We investigated how the advancing and receding contact angle of the moving water droplet changes on a solid surface having various characteristic energies. From the MD simulation results, we obtained the density profile defined as the number of water molecules at a given position. Then, assuming the water droplet periphery to be a circle, we calculated the contact angles by using a nonlinear fitting of the half-density contour line. The present simulation clearly shows the different profile of the advancing and receding contact angle for these three different interaction potential between the water droplet and the solid surface.

• Journal of Korean Medical classics
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• v.21 no.3
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• pp.83-90
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• 2008

"Eumyang-ihamnon(陰陽離合論)", from aspects of the Samjae theory[三才論], presents the unique insight for understanding dynamics of three Eum and three Yang[三陰三陽] throughout human body in fundamental level, defining purpose and essence of three Eum and three Yang motion. Furthermore, it indicates Bunbu(分部) of three Eum and three Yang, utilizing principles of Yukhap(六合), which serves as logical basis of three Eum and three Yang Byeonjeung(辨證). With theoretical meaning and practical values of "Eumyang-ihamnon(陰陽離合論)", this study investigates significance of three Eum and three Yang-Ihap-Motion in terms of the Samjae theory[三才論] and clinical uses of the three Eum and three Yang Bunbu theory[三陰三陽分部論].

• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.744-749
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• 2007

Kinematic and kinetic analysis has been performed for Soft Golf swings utilizing realistic three dimensional computer simulations based on three dimensional motion tracking data. Soft Golf is a newly developed recreational sport in South Korea aimed to become a safe and easy-to-learn sport for all ages. The advantage of Soft Golf stems from lighter weight of the club and much larger area of the sweet spot. This paper tries to look into kinematic and kinetic aspects of soft golf swings compared to regular golf swing and find the advantages of lighter Soft Golf clubs. For this purpose, swing motions of older aged participants were captured and kinematic analysis was performed for various kinematic parameters such as club head velocity, joint angular velocity, and joint range of motions as a pilot study. Kinetic analysis was performed by applying kinematic data to computer simulation models constructed from anthropometric database and the measurements from the participants. The simulations were solved using multi-body dynamics solver. Firstly, the kinematic parameters such as joint angles were obtained by solving inverse dynamics problem based on motion tracking data. Secondly, the kinetic parameters such as joint torques were obtained by solving control dynamics problem of making joint torque to follow pre-defined joint angle data. The results showed that mechanical loadings to major joints were reduced with lighter Soft Golf club.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.121-131
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• 2013

The characteristics of flame dynamics occurring near the bluff body was experimentally investigated in a model combustor with V-gutter bluff body. Measurements of chemiluminescence with high speed camera and PIV were performed for visualization of flame structure. Flashback occurs due to the change of pressure gradient in the combustor, and the flashback distance depends on equivalent ratio. Unstable flames can be classified into three types depending on the flashback distance and structure. When the flame goes over the bluff body, an unusual flame structure occurs at the front of the bluff body. Re-stabilization takes place as the flame moves downstream of the combustor. This process is supported by a strong vortex structure behind the bluff body.

• Journal of the Korean Society of Costume
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• v.24
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• pp.143-155
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• 1995

Unlike pure art such as painting and sculpture, dressmaking , a field of special plastic art, is characterized by its physical and functional nature. Having an inseparable relation with form, it is a field of art expressiion the human innersense of beauty in correlation with other various fields of art. In this respect, I think it should be necessary for us to study the forms of art from the past in order to study the forms of art from the past in order to study the correlations and mutual influencies between forms of pure art and dressmaking and to understand modern dressmaking from the standpoint of art. In this context, this study is an attempt to analze how the form and characteristics of OP ART , which represents the trends of the 1960's is embodied in modern dresses. The results are as follows : Fist , the expression of OP ART in dresses have visual effects harmonizing with bodily movements and , also, expanded the range and dynamics of expression which resulted from the introduction of visual phenomena in a fresh new sense by not limiting itself to the suggestion of patterns of OP ART. Second, OP ART paintings expressed the mobility and rhythimicity of a body in a limited space in a two-dimensional plane way of expression . When a dress is worn, however, it expands such mobility and rhythmicity in a cubic , three-dimensional way, maximizing the effects of , and boldly expression, OP ART, it can also create a new silhuette and ability of formation by seeking an open expression of OP ART rather than an expression of OP ART it self , due to the infinite possibility and unpredictability by the dynamics of movements and the elements principle of designs. Third , by applying the patterns of OP ART to dresses, we can obtain special visual effects of design, cover up the body's weak points, and create a desired three -dimensional sense by highlighting the beauty of the body's curved lines. Although modern dresses and OP ART are different genres of art, both have something in common in their pusuits. Since there is a infinite possibility in OP ART, there should be continuous attempts to combine dresses and art satisfying the sense of the times, which will lead dressmaking to a higher-dimensional dressmaking plastic art.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.26-32
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• 2019

This study was conducted to analyze the stresses by impact loads on front-end loaders attached to tractors using flexible multi-body dynamics. The model was designed and validated by comparing previous experimental data with the simulation data obtained in this study. Nine sets of conditions were designed using three weights (500, 300, and 100 kg) loaded inside a bucket and three heights (1700, 1350, and 1000 mm) of the bucket from ground level. A parametric study was carried out at five locations for two types of parts of a front-end loader. All the safety factors for the five locations under all conditions were calculated and were greater than 1. Thus, the designs of the front-end loaders were structurally safe. Based on this study, front-end loaders attached to tractors can be designed effectively in terms of cost and safety.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.239-247
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• 2013

Recently renewable energy such as offshore wind energy takes a higher interest due to the depletion of fossil fuel and the environmental pollution. This paper deals with multi-body dynamics (MBD) analysis technique for offshore wind turbine system considering aerodynamic loads and Thevenin equation used for determination of electric generator torque. Dynamic responses of 5MW offshore wind turbine system are evaluated via the MBD analysis, and the system is the horizontal axis wind turbine (HAWT) which generates electricity from the three blades horizontally installed at upwind direction. The aerodynamic loads acting on the blades are computed by AeroDyn code, which is capable of accommodating a generalized dynamic wake using blade element momentum (BEM) theory. In order that the characteristics of dynamic loads and torques on the main joint parts of offshore wind turbine system are simulated similarly such an actual system, flexible body modeling including the actual structural properties are applied for both blade and tower in the multi-body dynamics model.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.3
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• pp.349-360
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• 2012

In this study, the accuracy of CSD (Comprehensive Structural Dynamics) analysis on the evaluation of blade aeroelastic responses and structural loads of HART(Higher harmonic Aeroacoustic Rotor Test) II baseline rotor is assessed using a comprehensive rotorcraft dynamics code, CAMRAD II, and a nonlinear flexible multi-body dynamics analysis code, DYMORE. Considering insufficient measurement data for HART II rotor, prescribed airloads computed by a three-dimensional compressible flow solver KFLOW are used to replace the lifting-line airloads and thereby enhance the prediction capability of the comprehensive analyses. The CSD results on blade elastic deflections using the prescribed airloads indicate more oscillatory behavior than those by lifting-line based approaches, but the wave pattern becomes improved by including artificial damping into the rotor system. It is demonstrated that the structural load predictions are improved significantly by the prescribed airloads approach against the measured data, as compared with an isolated CSD analysis.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1835-1844
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• 2001

The turbulent flow with wake, reattachment and recirculation is a very important problem that is related to vehicle dynamics and aerodynamics. The Smagorinsky Model (SM), the Dynamics Subgrid Scale Model (DSM), and the Lagrangian Dynamic Subgrid Scale Model (LDSM) are used to predict the three-dimensional flow field around a bluff body model. The Reynolds number used is 45,000 based on the bulk velocity and the height of the bluff body. The fully developed turbulent flow, which is generated by the driver part, is used for the inlet boundary condition. The Convective boundary condition is imposed on the outlet boundary condition, and the Spalding wall function is used for the wall boundary condition. We compare the results of each model with the results of the PIV measurement. First of all, the LES predicts flow behavior better than the k-$\xi$ turbulence model. When ew compare various LES models, the DSM and the LDSM agree with the PIV experimental data better than the SM in the complex flow, with the separation and the reattachment at the upper front part of th bluff body. But in the rear part of the bluff body, the SM agrees with the PIV experimental results better than them. In this case, the SM predicts overall flow behavior better than the DSM nd the LDSM.