• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 가을 학술발표회 논문집
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• pp.127-132
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• 1992

The effect of 5 typical rise ratio(h/a=2/9, 5/18, l/3, l/2, 2/3) on the buckling characteristics of single-layer latticed domes with rectangular network under the external pressure are the theoretically studied on the basis of geometically nonlinear FEM and shell analogy method. The loading conditions are 4 types, that is, 1) the uniform pressure loading 2)the uniform snow loading 3) the half - sided asymmetric pressure loading 4) the half - sided asymmetric snow loading.

• 한국해양공학회지
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• 제29권3호
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• pp.255-262
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• 2015

The present study developed a numerical simulation tool for the coupled dynamic analysis of multiple turbines on a single floater (or Multiple Unit Floating Offshore Wind Turbine (MUFOWT)) in the time domain, considering the multiple-turbine aero-blade-tower dynamics and control, mooring dynamics, and platform motions. The numerical tool developed in this study was designed based on and extended from the single-turbine analysis tool FAST to make it suitable for multiple turbines. For the hydrodynamic loadings of floating platform and mooring-line dynamics, the CHARM3D program developed by the authors was incorporated. Thus, the coupled dynamic behavior of a floating base with multiple turbines and mooring lines can be simulated in the time domain. To investigate the effect of asymmetric aerodynamic loading on the global performance and mooring line tensions of the MUFOWT, one turbine failure case with a fully feathered blade pitch angle was simulated and checked. The aerodynamic interference between adjacent turbines, including the wake effect, was not considered in this study to more clearly demonstrate the influence of the asymmetric aerodynamic loading on the MUFOWT. The analysis shows that the unbalanced aerodynamic loading from one turbine in MUFOWT may induce appreciable changes in the performance of the floating platform and mooring system.

• 제어로봇시스템학회논문지
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• 제12권7호
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• pp.713-718
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• 2006

Supersonic jet fighter aircraft have several different weapon loading configuration to support air-to-air combat and air-to-ground delivery of weapon modes. Especially, asymmetric loading configurations could result in decreased handling qualities for the pilot maneuvering of the aircraft. The design of the T-50 lateral-directional roll axis control laws change from beta-betadot feedback structure to simple roll rate feedback structure and gains such as F-16 in order to improve roll-off phenomena during pitch maneuver in asymmetric loading configuration. Consequently, it is found that the improved control law decreases the roll-off phenomenon in lateral axes during pitch maneuver, but initial roll response is very fast and wing pitching moment is increased. In this paper, we propose the lateral control law blending between beta-betadot and simple roll rate feedback system in order to decreases the roll-off phenomenon in lateral axes during pitch maneuver without degrading of roll performance.

• 산업경영시스템학회지
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• 제35권2호
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• pp.30-36
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• 2012

This study is aimed to show that an asymmetric load in the frontal plane leads to an increase in low back loading and fatigue in comparison with a symmetric load when workers lift an external weight by investigating previous studies and verifying the phenomenon with an experiment. Ten male subjects are required to lift and hold an given external load at 70cm height during 50sec, then the EMG amplitude and median frequency on bilateral low back muscle groups (Longissimus, Iliocostalis, and Multifidus) are recorded and analyzed. Independent variables are two-level load weight (13kg, 20kg) and three-level LCG (Center, 6.5cm to the right, and 13cm to the right), and dependent variables are EMG amplitude average, difference, and Fatigue Index (FI). Results show that load weight increases significantly amplitude average and FI, but LCG does significantly amplitude difference and FI significantly (P-value < 0.05). Also the correlation coefficient between amplitude difference and FI is over 0.99. These implies that trunk loading should be explained by not EMG amplitude but muscle fatigue aspect since the association between an external load and amplitude is linear, but the relationship between an external load and median frequency as muscle fatigue index is almost exponential.

• Advances in nano research
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• 제7권1호
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• pp.25-38
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• 2019

This research is aimed at studying the asymmetric thermal buckling of porous functionally graded (FG) annular nanoplates resting on an elastic substrate which are made of two different sets of porous distribution, based on nonlocal elasticity theory. Porosity-dependent properties of inhomogeneous nanoplates are supposed to vary through the thickness direction and are defined via a modified power law function in which the porosities with even and uneven type are approximated. In this model, three types of thermal loading, i.e., uniform temperature rise, linear temperature distribution and heat conduction across the thickness direction are considered. Based on Hamilton's principle and the adjacent equilibrium criterion, the stability equations of nanoporous annular plates on elastic substrate are obtained. Afterwards, an analytical solution procedure is established to achieve the critical buckling temperatures of annular nanoplates with porosities under different loading conditions. Detailed numerical studies are performed to demonstrate the influences of the porosity volume fraction, various thermal loading, material gradation, nonlocal parameter for higher modes, elastic substrate coefficients and geometrical dimensions on the critical buckling temperatures of a nanoporous annular plate. Also, it is discussed that because of present of thermal moment at the boundary conditions, porous nanoplate with simply supported boundary condition doesn't buckle.

• Structural Engineering and Mechanics
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• 제30권1호
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• pp.21-36
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• 2008

The static response of a finite beam resting on a tensionless Pasternak foundation and subjected to a concentrated vertical load is assessed in this study. The concentrated vertical load may be applied at the center of the beam, or it may be offset from the center. The tensionless character of the foundation results in the creation of lift-off regions between the beam and the foundation. An analytical/ numerical solution is obtained from the governing equations of the contact and lift-off regions to determine the extent of the contact region. Although there is no nonlinear term in the equations, the problem shows a nonlinear character since the contact region is not known in advance. Due to that nonlinearity, the essentials of the problem (the coordinates of the lift-off points) are calculated numerically using the Newton-Raphson technique. The numerical results are presented in figures to illustrate the behaviours of the free-free and pinned-pinned beams under symmetric or asymmetric loading. The figures illustrate the effects of the shear foundation parameter and the symmetric and asymmetric loading options on the variation of the contact lengths and the displacement of the beam.

• 한국항공우주학회지
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• 제33권2호
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• pp.106-112
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• 2005

현대의 고성능 전투기는 공대공 및 공대지 전투 임무를 수행하기 위해 여러 가지 무장 형상을 하고 있고, 무장투하 시 비대칭 형상(Asymmetric Configuration)으로 임무를 수행하는 경우가 많다. 현재, 개발이 진행 중인 T-50 훈련기의 비대칭 무장형상 비행시험에서 세로축 기동 시 가로축 방향으로 조종사가 원하지 않는 운동이 발생하는데, 이는 항공기 안정성 및 조종성에 영향을 미칠 수 있다. 본 연구에서는 이러한 현상을 개선하기 위하여 기존의 가로축 제어법칙인 미끄럼각-미끄럼각속도 귀환 구조를 F-16과 같이 단순 롤각속도 귀환구조로 적용하였다. 연구결과, 단순 롤각속도 귀환구조로 가로축 제어법칙을 변경하였을 때 비대칭 무장형상에서 세로축 기동 시 가로축 운동의 발생이 줄어들었으며, 시스템의 안정도 여유는 설계기준에 만족한다는 것을 알 수 있었다.

• 대한기계학회논문집A
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• 제20권10호
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• pp.3105-3112
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• 1996

Asymmetric creep behaviors of ceramics under high temperature were investigated. Based on the Norton's power-low creep equation, multidirectional creep equations were proposed for general geometric loading conditions. The proposed equations were implemented into finite element program (ABAQUS) to simulate creep behaviors of ceramics in complicated loading conditions. The calculated results were compared with experimental data for uniaxial compression of Si-SiC C-ring and flexure of Si-SiC and $Al_2O_3$ in the literature. The finite element results agreed well with experimental data when the principal stresses are smaller than the threshold stress for creep damage. A good agreement was also obtained for damage zone in Si-SiC bending creep specimen compared with experimental data.

• 한국공간구조학회논문집
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• 제12권4호
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• pp.81-90
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• 2012

The concrete-filled tube (CFT) column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. Its Solution, 2 members of ㄷchennel in which Internal diaphragm is installed were welded beforehand and the method of making Rectangular Steel Tube was proposed. According to upside and downside junction shape, Internal diaphragm suggested as symmetric specimen and asymmetric specimen. The upper and lower diaphragm of the Symmetric specimen used the same horizontal and The upper diaphragm of the Asymmetric specimen used the horizontal plate and the lower diaphragm used the vertically plate. In this research, 4 T-shape column to beam steps connections were tested with cyclic loading experiment in order to evaluate the structural capability of the offered connection. Symmetric specimens be a failure in 0.03rad from beam flange. And Asymmetric specimens be a failure in 0.05rad from column interface. The comparison results of All specimens shown similar to energy absorption capacity in 0.02rad.

• 한국세라믹학회지
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• 제52권6호
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• pp.417-422
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• 2015

In this study, we investigate the effect of porous $Al_2O_3$ substrate on the strengths of asymmetric structures after we prepare such a structure consisting of a dense $Li_2ZrO_3$ top layer and porous $Al_2O_3$ substrate layer. The porosity and elastic modulus of the substrate layer are controlled by sintering temperature, which has three values of 1150, 1250 and $1350^{\circ}C$. The porosity is controlled in the range of ~ 30-50 vol%, elastic modulus is ~80-120 GPa and elastic mismatch $E_s/E_c$ is ~ 0.6-1.0. Indentation stress-strain curves are obtained and analyzed to evaluate the yield stress of the asymmetric structure by concentrated local loading of WC balls. Conventional flexural strengths are also obtained to evaluate the strength of the asymmetric structure. The results indicate that the local yield strength of the asymmetric structure has mid-values between the top and the substrate layer; however, the flexural strength of the asymmetric structure are mainly influenced by elastic modulus and strength of the substrate.