• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.340-343
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• 2007

The differential equations governing free, in-plane vibrations of non-circular arches with the translational (radial and tangential directions) and rotational springs at the ends, including the effects of rotatory inertia, shear deformation and axial deformation, are solved numerically using the corresponding boundary conditions. The lowest four natural frequencies for the parabolic geometry are calculated over a range of non-dimensional system parameters: the arch rise to span length ratio, the slenderness ratio, and the translational and rotational spring parameters.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.815-818
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• 2006

This paper deals with the free, in-plane vibrations of curved members with the translational(radial and tangential directions) and rotational springs at the ends. The governing differential equations for the circular curved member are solved numerically using the corresponding boundary conditions. The lowest three natural frequencies and the corresponding mode shapes are obtained over a range of non-dimensional system parameters: the subtended angle, the slenderness ratio, the translational spring stiffness, and the rotational spring stiffness.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1181-1184
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• 2007

이 논문에서는 단부가 힌지와 회전스프링으로 지지된 원호 아치의 면내 자유진동에 대한 지배 미분방정식을 수치해석하여 대상 구조에 대한 최저차 4개의 고유진동수 및 진동형을 산출하였다. 축변형, 회전관성 및 전단변형 효과를 고려한 지배방정식을 채택하였으며, 해석결과로서 아치 중심각, 세장비 및 단부의 회전스프링상수 변화에 따른 고유진동수 및 진동형의 변화를 고찰하였다.

• Structural Engineering and Mechanics
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• 제35권2호
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• pp.217-240
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• 2010

A semi-analytical method is presented for accurately prediction of the free vibration behavior of generally laminated composite plates with arbitrary boundary conditions. The method employs the technique of separation of spatial variables within Hamilton's principle to obtain the equations of motion, including two systems of coupled ordinary homogeneous differential equations. Subsequently, by applying the laminate constitutive relations into the resulting equations two sets of coupled ordinary differential equations with constant coefficients, in terms of displacements, are achieved. The obtained differential equations are solved for the natural frequencies and corresponding mode shapes, with the use of the exact state-space approach. The formulation is exploited in the framework of the first-order shear deformation theory to incorporate the effects of transverse shear deformation and rotary inertia. The efficiency and accuracy of the present method are demonstrated by obtaining solutions to a wide range of problems and comparing them with finite element analysis and previously published results.

• 한국농공학회지
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• 제42권1호
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• pp.105-112
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• 2000

This paper deals with the free vibrations of columns immersed in fluid. The column model is based on the classical Bernoulli-euler theory which neblects the effects of rotatory inerital and shear deformation. The eccentricity and rotatory inertial of the concentrated mass at the top are taken into accuont. In the governing equation for the free vibration of column, thedensity of immersed part was midified to account for theadded fluid mass. The govering differential equations are solved numerically using the corresponding boundary conditions. The lowest four natural frequencies and corresponding mode shapes are calculated over a range of non-dimensional system parameters ; the mas density ration of fluid to column, the ratio of fluid depth to span length, the ratio of tip mass to total column mass, the dimensionless mass moment of inertia, and the eccentricity.

• 대한전기학회논문지
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• 제43권6호
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• pp.971-981
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• 1994

In this paper, we consider feedback-linearizing control of VR (Variable Reluctance) motors which have been increasingly used in high performance direct-drive applications. We characterize all torque controllers that can make the generated torque of a VR motor linear to torque command but without torque ripple. The torque controlles maximize the range of torque commands which are admissible under the physical limitation in stator currents. The whole class of all such torque controllers is parameterized in the explicit form which contains a function to be chosen freely. This free function can be used to achieve other control objectives as well as linear dynamic characteristics. As the examples for optimal choices of the free function, we actually determine two optimal free functions, one for minimal rate of change in current commands and the other for minimal power loss due to stator resistance. To illuminate further the practical use of torque controllers proposed in this paper, we present some experimental results for the case of a commercially available VR motor.

• 약학회지
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• 제44권6호
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• pp.613-619
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• 2000

The author examined whether the methanol extracts of Opuntia ficus-indica fruit and Saururus chinensis have the inhibitory action on xanthine/xanthine oxidase (X/XO)-, $FeCl_2/ascorbic$ acid- and arachidonic acid-induced neurotoxicity in mouse cortical cell cultures. The methanol extracts ($10\;{\mu}g/ml{\sim}1\;mg/ml$) of Opuntia ficus-indica and Saururus chinensis were exhibited 53-89% and $48{\sim}100%$ inhibitory action on X/XO-induced neurotoxicity, respectively. At the range of same concentration, both extracts also attenuated the $FeCl_2/ascorbic$ acid-induced neurotoxicity by $35{\sim}100%$ and $15{\sim}98%$, respectively. In arachidonic acid neurotoxicity, the methanol extract (1 mg/ml) of Opuntia ficus-indica and Saururus chinensis reduced neuronal injury by 22% and 38%, respectively. These results suggest that Opuntia ficus-indica fruit and Saururus chinensis may contribute the neuroprotection in certain free radical-mediated neuronal injury.

• Journal of Welding and Joining
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• 제20권2호
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• pp.77-81
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• 2002

Many kinds of Pb-free solder have been investigated because of the environmental concerns. Sn-Ag-Cu system is well blown as most competitive Pb-free solder. However, since Sn-Ag-Cu system has relatively high melting point compared to Sn-Pb eutectic, it may a limitation, the some application. In this study, Bi and In contained solder of $Sn_3Ag_8Bi_5In$ which has relatively lower melting point, $188~204^{\circ}C$, was investigated. $Sn_3Ag_8Bi_5In$ solder ball of $500\mu\textrm{m}$ diameter was set on the Ni/Cu/Cr-UBM and reflow soldered in the range of $220~240^{\circ}C$ for 5~15s. The maximum shear strength of the solder ball was around 170mN by reflowing at $240^{\circ}C$ for 10s. Intermetallic compound formed on the UBM of Si-wafer was analysed by SEM(scanning electron microscope) and XRD(X-ray diffractometer).

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2003년도 하계학술대회
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• pp.379-381
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• 2003

155Mbps 단거리용 무선 광통신 모듈을 120m 의 짧은 거리에 설치하였다. 그 결과 99.98% 이상의 error free availability와 99.99% 이상의 severely error free second rating을 가졌다. error의 요인을 분석한 결과 30mm/h 정도의 비에도 크게 영향을 받지 않음을 알 수 있었다. 맑은 날에도 error가 발생하였는데 그 원인은 날아가는 새와 같은 물체가 링크를 가리기 때문이었다.

• 대한두개안면성형외과학회지
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• 제19권2호
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• pp.131-134
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• 2018

Treacher Collins syndrome is a congenital disorder that is characterized with a wide range of cranio-facial deformities. Zygomatic hypoplasia or aplasia is one of the key features, and surgical reconstruction of the consequent depression on the zygomatic area is deemed necessary by many patients. Various surgical options are available-injectables, alloplastic materials, autologous grafting, and autogenous tissue transfer. It depends on each patient which technique to use. Here, we present a clinical case, in which bilateral free groin flaps were adopted in attempt to resolve the remnant aesthetic deformity associated with zygomatic depression, despite a series of previous surgical efforts, in a 25-year-old Treacher Collins syndrome male patient.