• Steel and Composite Structures
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• 제33권5호
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• pp.641-652
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• 2019

This paper investigates the effect of aftershocks on the seismic performance of self-centering (SC) prestressed concrete frames using the probabilistic seismic demand analysis methodology. For this purpose, a 4-story SC concrete frame and a conventional reinforced concrete (RC) frame are designed and numerically analyzed through nonlinear dynamic analyses based on a set of as-recorded mainshock-aftershock seismic sequences. The peak and residual story drifts are selected as the demand parameters. The probabilistic seismic demand models of the SC and RC frames are compared, and the SC frame is found to have less dispersion of peak and residual story drifts. The results of drift demand hazard analyses reveal that the SC frame experiences lower peak story drift hazards and significantly reduced residual story drift hazards than the RC frame when subjected to the mainshocks only or the mainshock-aftershock sequences, which demonstrates the advantages of the SC frame over the RC frame. For both the SC and RC frames, the influence of as-recorded aftershocks on the drift demand hazards is small. It is shown that artificial aftershocks can produce notably increased drift demand hazards of the RC frame, while the incremental effect of artificial aftershocks on the drift demand hazards of the SC frame is much smaller. It is also found that aftershock polarity does not influence the drift demand hazards of both the SC and RC frames.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.137-140
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• 2003

Cu+ ions drift diffusion in different dielectric materials is evaluated. The diffusion is investigated by measuring shift in the flatband voltage of capacitance/voltage measurements on Cu gate capacitors after bias temperature stressing. At a field of 1.lMV/cm and temperature $200^{\circ}C$, $250^{\circ}C$, $300^{\circ}C$ for 1H, 2H, 5H. The Cu+ ions drift rate of polyimide$(2.8{\leq}k{\leq}3.2)$ is considerably lower than thermal oxide. Also Cu+ drift rate of polyimide is similar to PECVD oxide. But, polyimide film is even more resistant to Cu drift diffusion and thermal effect than Thermal oxide, PECVD oxide: This results got a comparative reference. The important conclusion is that polyimide film is strongly dielectric material by thermal effect and Cu drift diffusion.

• 한국해양공학회지
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• 제37권4호
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• pp.145-157
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• 2023

Due to a recent increase in maritime activities in South Korea, the frequency of maritime distress is escalating and poses a significant threat to lives and property. The aim of this study was to validate a drift trajectory prediction technique to help mitigate the damages caused by maritime distress incidents. In this study, OpenDrift was verified using satellite drifter data from the Korea Hydrographic and Oceanographic Agency. OpenDrift is a Monte-Carlo-based Lagrangian trajectory modeling framework that allows for considering leeway, an important factor in predicting the movement of floating marine objects. The simulation results showed no significant differences in the performance of drift trajectory prediction when considering leeway using four evaluation methods (normalized cumulative Lagrangian separation, root mean squared error, mean absolute error, and Euclidean distance). However, leeway improved the performance in an analysis of location prediction conformance for maritime search and rescue operations. Therefore, the findings of this study suggest that it is important to consider leeway in drift trajectory prediction for effective maritime search and rescue operations. The results could help with future research on drift trajectory prediction of various floating objects, including marine debris, satellite drifters, and sea ice.

• 한국강구조학회 논문집
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• 제17권3호통권76호
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• pp.285-294
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• 2005

고층 건물 변위설계는 고층건물 설계의 핵심 기술 중의 하나이며, 재분배 기법은 실용적인 고층건물 변위설계법으로 인식되고 있다. 재분배 기법은 구조 물량을 재분배함으로서 전체 구조물량의 변화없이 제어하고자 하는 변위를 최소화시키는 방법으로서, 재분배기법 적용에 의해서 최종 얻어지는 물량은 초기 물량의 영향을 받게 된다. 초기 물량이 과다한 모델의 경우, 재분배 기법을 적용하면 허용 변위는 충분히 만족하지만 물량 측면에서는 그 만큼의 절감 여지를 내포하고 있다고 볼 수 있다. 그러므로 중량 조절계수를 구조정식화에 포함시켜서 변위설계시 초기 설계안의 물량에 영향을 받지 않는 고층건물 변위설계 기법을 개발하였다. 제안된 변위설계법을 프레임-전단벽 구조물의 변위설계에 적용하여 그 결과를 분석한 결과, 제안된 방법은 초기 물량의 영향을 받지 않으며 고층건물 변위설계가 가능하였다.

• Journal of Information Processing Systems
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• 제15권6호
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• pp.1350-1364
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• 2019

The ice damage occurs frequently in cold and dry region of western China in winter ice period and spring thaw period. In the drift ice condition, it is easy to form different extrusion force or impact force to damage tunnel lining, causing project failure. The failure project could not arrive the original planning and construction goal, giving rise to the water allocation pressure which influences diversion irrigation and farming production in spring. This study conducts the theoretical study on contact-impact algorithm of drift ices crashing diversion tunnel based on the symmetric penalty function in finite element theory. ANSYS/LS-DYNA is adopted as the platform to establish tunnel model and drift ice model. LS-DYNA SOLVER is used as the solver and LS-PREPOST is used to do post-processing, analyzing the damage degrees of drift ices on tunnel. Constructing physical model in the experiment to verify and reveal the impact damage mechanism of drift ices on diversion tunnel. The software simulation results and the experiment results show that tunnel lining surface will form varying degree deformation and failure when drift ices crash tunnel lining on different velocity, different plan size and different thickness of drift ice. The researches also show that there are damages of drift ice impact force on tunnel lining in the thawing period in cold and dry region. By long time water scouring, the tunnel lining surfaces are broken and falling off which breaks the strength and stability of the structure.

• Communications for Statistical Applications and Methods
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• 제14권1호
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• pp.241-254
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• 2007

This paper propose a new short-term interest rate model having a different nonlinear drift function and the same diffusion coefficient with Chan et al. (1992) model. The fractional polynomial power of the drift function in our model is linked to the local volatility elasticity of the diffusion coefficient. While the nonlinear drift function estimated by $A\"{\i}t$-Sahalia (1996a) and others has a feature that higher interest rates tend to revert downward and low rates upward, the drift function estimated by our nonlinear model shows that higher interest rate mean-reverts strongly, but, medium rates has almost zero drift and low rates has a very small drift. This characteristic coincides the empirical result based on the nonparametric methodology by Stanton (1997) and the implication by the scatter plot of the short rate data.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.749-756
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• 2000

Chemical application, one of the most important crop management processes happened to cause spray drift, that would threaten farmers in field as well as dwellers in rural region. Spray drift was affected by micro-meteorological parameters. In Korea, a boom sprayer was introduced but good effects of a boom sprayer was not evaluated. A study to evaluate short distance drift characteristics of a boom sprayer in paddy fields has been undergoing and determining wind characteristics in paddy field was the main purpose of this paper. Micro-meteorological information has been pre-requisite information for evaluating drift in both long and short distances or in both theoretical and experimental ways. Wind velocity, Reynolds stresses, turbulence intensity, skewness, kurtosis etc. were evaluated with height from the ground using a 2-dimensional probe and a hot wire anemometer system.

• International Journal of Aeronautical and Space Sciences
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• 제15권3호
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• pp.293-301
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• 2014

We present a study of vertical dynamics control of an electrostatically levitated gyro-accelerometer considering the wobbling effect and propose a tilt stabilization method with newly introduced control electrodes. Typically, a rotor in a vacuum rotates at high velocity, which may create a drift rate and lead to displacement instability due to the tilt angle of the rotor. To analyze this, first we set up a vertical dynamic equation and determined simulation results regarding displacement control. After deriving an equation for drift dynamics, we analyzed the drift rate of the rotor and the wobbling effect for displacement control quantitatively. Then, we designed new sub-electrodes for moment control that will decrease the drift amplitude of wobbling dynamics. Finally, a simulation study demonstrated that the vertical displacement control with the wobbling compensation electrodes mitigated the rotor's drift rate, showing the effectiveness of the newly proposed control electrodes.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.143-149
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• 2004

In this paper, an automation model for drift design of high-rise buildings using resizing algorithms is proposed. Drift, in the model, includes the maximum lateral displacement at the top and inter-story drifts of a high-rise building subjected to both wind and seismic load. Resizing algorithms for high-rise buildings in various systems and material developed in previous researches are used as a drift control module. As an input to drift control algorithms, member forces for calculation of member displacement participation factors are obtained from commonly-used commercial softwares. The automation model is composed of 4 modules: initial modeling, drift control, stress check, and final verification modules. Each module in the model is described in detail in this paper.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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• pp.151-154
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• 2008

본 연구는 고층 구조물의 횡변위를 정량적으로 제어할 수 있는 효율적인 횡변위 제어 최적화기술을 제시하고자한다. 이를 위해 최적화 알고리즘의 정식화 과정이 제안되며 이를 바탕으로 횡변위제어 최적화 프로그램이 개발된다. 본 연구에서 제시한 횡변위 제어기술의 효용성을 검토하기 위해 130층 전단벽 코어 모델을 고려하였다.