• Journal of Information Processing Systems
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• v.15 no.6
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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.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.2
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• pp.11-17
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• 2000

The drift and movement of oil slick in the sea are closely related to the flows at the sea surface (at 0m depth) because specific gravity of an oil is lighter than that of sea water. As an effort toward a development of realistic model for oil spill drift on the sea surface, a study on sea surface wind-induced drift (skin drift) at 4 coastal regions of Korea was carried out. In this study, skin drifts were inferred from difference between the flow at the sea surface and that in underwater (at 1.5m depth). The average speed of skin drift in our experiments was 2.9% of wind speeds and the average direction of skin drift to wind was deflected to the right by 18.6°. The results of this experiment were used in the modelling of the skin drift as a prompt response of time-variable wind. The modelled skin drift, which corresponds to observed wind, successfully reproduced the observed trajectories of sea surface flows.

• Journal of Korean Port Research
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• v.14 no.3
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• pp.353-360
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• 2000

In this study a drift prediction model based on fluid dynamics theory is introduced. The essential effects of environmental loads and target characteristics are taken into account from a fluid dynamics point of view. The governing equations of motion are derived from Netwon's law of dynamics. In the mathematical formulation only three degrees of freedom(surge, sway, yaw) of the drifting object are assumed and the environmental loads considered are the forces and moments by wind and current. A computer algorithm for this model is implemented to obtain the numerical result in the time domain. The preliminary tests for model verification are conducted and the results are compared with the field experiment data as well as leeway formula suggested from the field test data.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.63-71
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• 2000

In this study a drift prediction model based on fluid dynamics theory is introduced. The essential effects of environmental loads and target characteristics are taken into account from a fluid dynamics point of view. The governing equations of motion are derived from Newton's law of dynamics. In the mathematical formulation only three degrees of freedom(surge, sway, yaw) of the drifting object are assumed and the environmental loads considered are the forces and moments by wind and current. A computer algorithm for this model is implemented to obtain the numerical result in the time domain. The preliminary tests for model verification are conducted and the results are compared with the field experiment data as well as leeway formula suggested from the field test data.

• Applied Microscopy
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• v.38 no.4
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• pp.383-386
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• 2008

In performing in situ heating transmission electron microscopy (TEM) for materials characterizations, arising concerns such as specimen drifts and unintentional Cu contamination are discussed. In particular, we analysed the thermal and mechanical characteristics of in situ heating holders to estimate thermal drift phenomena. From the experimental results, we suggest an empirical model to describe the thermal drift behavior so that we can design an effective plan for in situ heating experiment. Practical approaches to minimize several hindrances arisen from the experiment are proposed. We believe that our experimental recommendations will be useful for a microscopist fascinated with the powerful potential of in situ heating TEM.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.2
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• pp.19-21
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• 1978

The electrical drift mobility of charge carrier of Cholesteryl Benzoate was measured by Polarity inversion method in the temperature range 140~ 185$^{\circ}C$. with a view to revealing the mechanism of charge carrier transport. The electrical drift mobility of charge carrier of that increased from 2.5$\times$10-7$\textrm{cm}^2$/V.sec to 2.0$\times$10-6$\textrm{cm}^2$/v.sec as the temperature increased. As a result of the experiment, the mechanism of current transport is believed to be ionic mechanism.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.144-147
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• 2003

Cu+ ions drift diffusion in formal oxide film and SiOCH film for interlayer dielectric 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 0.2MV/cm and temperature $200^{\circ}C,\;300^{\circ}C,\;400^{\circ}C,\;500^{\circ}C$ for 10min, 30min, 60min. The Cu+ ions drift rate of $SiOCH(k=2.85{\pm}0.03)$ film is considerable lower than termal oxide. As a result of the experiment, SiOCH film is higher than Thermal oxide film for Cu+ drift diffusion resistance. The important conclusion is that SiOCH film will solve a causing reliability problems aganist Cu+ drift diffuion in dielectric materials.

• Journal of Korea Foresty Energy
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• v.18 no.2
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• pp.84-91
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• 1999

The objective of this study was to present creep and the effects of mechano-sorptive deflection of drift pin moment resisting joint between LVL members under changing relative humidity (RH) conditions. The LVL members with steel gusset were jointed by a square pattern of eight injected drift pin. Three diameter drift pins were used to test specimens (6mm, 10mm, and 16mm). The creep test was conducted under two constant loading conditions : one at 30 kgf(840 kgf-cm) and the other at 60 kgf(1680 kgf-cm). The experiment was conducted in an open shed outside. (1)The total rotation creep model of moment resisting joing can be expressed as the sum of the creep of controlled environment (3-parameter model), dimensional change and mechano-sorptive deflection resulting from the variable environment. (2)Mechanosorptive rotation creep is recoverable as moisture content increases during adsorption. Least squares method for linear regression analysis was performed using mechano-sorptive rotation creep as the dependent variable and moisture content as the independent variable. The slope of low moment specimens are compared with those of high moment. This means that low moment condition is more easily affected by changes in humidity than high moment conditions. (3)Although creep deflection is higher for small diameter drift pin than for large diameter drift pin, the shape of creep deflection curves for all specimens is similar.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.187-191
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• 2003

The motion and time-mean drift force of a 2-D floating BBDB in waves are studied with and without taking account of fluctuating air pressure in the air chamber. It has been found numerically that the drift for a of the BBDB is in the reverse direction of propagation of the incident waves over specific frequency ranges as found by McCormick through his experiment work. The drift force is calculated by Pinkster's near-field method. Since Maruo's formula method for the drift force is always positive, Maruo's formula is only approximate and should be replaced by the correct near-field method.

• Smart Structures and Systems
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• v.15 no.3
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• pp.881-896
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• 2015

The authors' research group has developed a noncontact type of sensors which directly measure the inter-story drift displacements of a building during a seismic event. Soon after that event, such seismically-induced drift displacement data would provide structural engineers with useful information to judge how the stories have been damaged. This paper presents a scheme of estimating the story cumulative plastic deformation ratios based on such measured drift displacement information toward the building safety monitoring. The presented scheme requires the data of story drift displacements and the ground motion acceleration. The involved calculations are rather simple without any detailed information on structural elements required: the story hysteresis loops are first estimated and then the cumulative plastic deformation ratio of each story is evaluated from the estimated hysteresis. The effectiveness of the scheme is demonstrated by utilizing the data of full-scale building model experiment performed at E-defense and conducting numerical simulations.