• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.1049-1052
• /
• 2004

In general, contrary to the CRTs with impulsive emission, liquid crystal displays have motion artifacts such as blurring. ghost image, decrease of dynamic CR(contrast ratio), and stroboscopic motion due to hold type driving method. In this paper, to improve motion picture quality of LCDs. impulsive driving method of black data insertion was applied to the OCB mode which is well known for its fast LC response time and wide viewing angle properties. Subject evaluation was carried out with CRT, TN, SIPS(Super IPS). and impulsive driving OCB. Moving picture image quality near CRT was obtained in impulsive OCB driving mode

• 한국소음진동공학회논문집
• /
• 제18권10호
• /
• pp.1024-1032
• /
• 2008

The vibration characteristics of a rotating cantilever beam undergoing impulsive force are investigated using wavelet transformation. The transient response induced by the impulsive force and the rigid body motion of the beam are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. The vibration characteristics of the beam can be analyzed in time-frequency domain with the wavelet transform method. Therefore, the effects of the impulsive force on the transient vibration characteristics of the beam can be investigated more effectively.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 춘계학술대회논문집
• /
• pp.890-895
• /
• 2005

This paper presents the dynamic analysis of a cantilever beam undertaking impulsive force that undergoes rigid body motion. The transient response of the beam induced by the impulsive force and the rigid body motion is calculated based on hybrid deformation variable modeling method by applying the Rayleigh-Ritz assumed mode method. The stiffness variation effect caused by the rigid body motion is considered in this modeling. The effects of the impulsive force position and the angular velocity on the transient responses of the beam are investigated through numerical studies.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2008년도 춘계학술대회논문집
• /
• pp.400-406
• /
• 2008

The vibration characteristics of a rotating cantilever beam undergoing impulsive force are investigated using wavelet transformation. The transient response induced by the impulsive force and the rigid body motion of the beam are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. The vibration characteristics of the beam can be analyzed in time-frequency domain with the wavelet transform method. Therefore, the effects of the impulsive force on the transient vibration characteristics of the beam can be investigated more effectively.

• Journal of Astronomy and Space Sciences
• /
• 제15권1호
• /
• pp.235-244
• /
• 1998

인공위성의 궤도조정에 사용되는 소모연료의 최적화를 위해, 비 선형 제어 시스템인 슬라이딩 제어 기법을 사용하여 지구 비대칭 중력장에 의해 섭동력을 고려한 궤도조정 문제의 해를 구하였다. 결합 방정식을 이용한 해법을 통해 총 속도 변화량이 최소가 되는 Lambert 궤도를 목표궤도로 설정하고 그에 따른 궤도조정 시간을 결정하였다. 결정된 궤도조정 시간이 종료되는 시점에서 제한된 추력에 의해 제어되는 인공위성의 상태 백터가 경계조건과 일치되도록 하기 위하여, 슬라이딩 제어를 반복적으로 사용하는 2단 슬라이딩 제어기법을 도입하였으며, 이를 인공위성 랑데뷰 문제에 적용하여 최적 에어방법에 의한 결과와 비교하였다. 새롭게 제안된 제어방법을 이용한 궤도조정은 이상적인 전이궤도인 Lambert 궤도와 근접한 궤도를 갖도록 하는 thrust-coast-thrust 형태의 추력을 나타내었으며, 이 때 필요한 속도의 변화량은 Lambert's two-impulsive 방법에 의한 값에 매우 근접한 값을 나타내었다. 또한 궤도조정 시간이 종료되었을 때, 궤도의 모든 상태변수들이 최종 경계조건과 거의 일치되는 결과를 얻을 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
• /
• pp.571-574
• /
• 2002

We propose modified concept that enables LCDs quasi-impulsive operations, and demonstrated a prototype AM-LCD that is suitable for displaying moving pictures combined with '2-Domain Half-V shaped switching mode' FLCD.

• 한국소음진동공학회논문집
• /
• 제16권3호
• /
• pp.226-232
• /
• 2006

This paper presents the dynamic analysis of an impulsively forced rotating cantilever beam with rigid body motion. The transient response induced by the impulsive force and the rigid body motion of the beam are calculated using hybrid deformation variable modeling with the Rayleigh-Ritz assumed mode methods. The stiffness variation effect due to the rigid body motion of the beam is considered in this study Also, the effects of the impulsive force position and the angular velocity on the transient responses of the beam are investigated through numerical works.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.943-947
• /
• 2008

Dynamic response characteristics of a beam undergoing impulsive force are investigated using the wavelet transform method in this study. When an impulse is applied to an arbitrary position of a beam, it will generate a structural deformation wave. The characteristics of the wave are changing in the domain of time and space. The maximum amplitude of each natural frequency mode and the time to reach the maximum amplitude are obtained in this study. The effects of the location of impulse on the variations of the dynamic characteristics is also investigated.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 춘계학술대회논문집
• /
• pp.1169-1176
• /
• 2002

Analytical model of beat response is derived on a slightly asymmetric ring and is veryfied by experiment. The asymmetric ring is a simplified model used to explain the beat property of a Korean bell. The asymmetric ring has mode pair having slight frequency difference in each radial mode. Each mode pair produces beat phenomenon by the interaction of the two close frequency components. Based on the analytical model, beat maps are first proposed and characteristics of beat on the circumference are detaily explained.

• 한국지진공학회논문집
• /
• 제21권4호
• /
• pp.153-161
• /
• 2017

Liquid storage tank is one of the major infrastructures and generally used to store gases, drinking and utilizing water, dangerous fluids, fire water and so on. According to the recent reports and experiences, the tank structures are damaged in many earthquakes due to their low energy dissipating capacity. Therefore, many researchers have been tried to know the dynamic properties of the tanks including liquids. However, vary limited experimental studies are carried out using relatively small tank models. In this study, a series of shaking table tests are performed with maximum 2 m cubic rectangular liquid storage tanks made of steel to measure the natural frequency and estimate damping coefficient of impulsive and convective mode of the tanks. Especially, the damping values under different shapes and excitation methods are estimated by logarithmic decrement method and half power band-pass method and compared with current design code and standards such as ASCE 7, Eurocode 8 and NZS. Test results show that the impulsive mode damping is around 2% which is proposed by general standards and codes but the impulsive mode damping is 0.13% average that is slightly lower than the code recommendation.