• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.955-958
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• 2002

A workflow is a flow of work supported by computers. An instance of a workflow is called case. Companies need to constantly refine their current workflows in order to meet various requirements. The change of current workflows is called dynamic change of the workflow. Since Ellis et al. proposed three change types, Flush, Abort, and Synthetic Cut-Over in 1995, various change types have been proposed. A promising change type is Migrate proposed by Sadiq et al., because Migrate changes workflow definitions immediately and makes the redo of cases minimum. However, the formal modeling and time-dependent analysis of Migrate has not been done. This paper proposes a method of computing change time of Migrate dynamic changes for time-dependent analysis. Change time is a measure for evaluating dynamic changes. We first show a Petri-nets-based model of Migrate dynamic changes. Then we present a method of computing change time based on the net model. Finally, we apply the method to 270 examples, and show experimental results, and comparison with Ellis et al..'s three change types.

• Communications for Statistical Applications and Methods
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• v.16 no.4
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• pp.587-594
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• 2009

In this paper the change point problem of the error terms in linear regression models is considered. Since fixed or stochastic independent variables and weakly dependent errors are assumed, usual multiple regression models and time series models including ARMA are covered. We use the estimates of probability density function based on residuals in order to test the distribution change of the unobserved errors. Under some mild conditions, the test using the residuals is proved to have the same limiting distribution as the test based on true errors.

• Advances in materials Research
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• v.11 no.1
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• pp.41-57
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• 2022

This paper is focused on delamination analysis of a multilayered inhomogeneous viscoelastic beam subjected to linear creep under constant applied stress. The viscoelastic model that is used to treat the creep consists of consecutively connected units. Each unit consists of one spring and two dashpots. The number of units in the model is arbitrary. The modulus of elasticity of the spring in each unit changes with time. Besides, the modulii of elasticity and the coefficients of viscosity change continuously along the thickness, width and length in each layer since the material is continuously inhomogeneous in each layer of the beam. A time-dependent solution to the strain energy release rate for the delamination is derived. A time-dependent solution to the J-integral is derived too. A parametric analysis of the strain energy release rate is carried-out by applying the solution derived. The influence of various factors such as creep, material inhomogeneity, the change of the modulii of elasticity with time and the number of units in the viscoelastic model on the strain energy release rate are clarified.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.132-136
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• 2005

It is widely accepted that the reading mechanism of Super-RENS(super-resolution near field structure) and Super-ROM(super-resolution read only memory) is closely related with non-linear temperature dependent material properties such as refractive indices, phase change. Furthermore, the dynamic change of the temperature distribution also an essential part of reading mechanism of Super-RENS/ROM. Therefore, the knowledge of the temperature distribution as a function a time is one of the important keys to reveal the physics of reading mechanism in Super-RENS/ROM. We calculated time-dependent temperature distribution in a 3-dimensional Super-ROM disk structure when moving laser beam is irradiated. With a help of commercial software FEMLAB which employed finite element method, we simulated the temperature distribution of ROM structure whose pit diameter is 120-nm with 50-nm depth. Energy absorption by moving laser irradiation, time variations of heat transfer processes, heat fluxes, heat transfer ratios, and temperature distributions of the complicate 3-dimensional ROM structure have been obtained.

• Management Science and Financial Engineering
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• v.4 no.2
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• pp.1-13
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• 1998

The Shortest Path Problem in Time-dependent Networks, where the travel time of each link depends on the time interval, is not realistic since the model and its solution violate the Non-passing Property (NPP:often referred to as FIFO) of real phenomena. Furthermore, solving the problem needs much more computational and memory complexity than the general shortest path problem. A new model for Time-dependent Networks where the flow speeds of each link depend on time interval, is suggested. The model is more realistic since its solution maintains the NPP. Solving the problem needs just a little more computational complexity, and the same memory complexity, as the general shortest path problem. A solution algorithm modified from Dijkstra's label setting algorithm is presented. We extend this model to the problem of Minimum Expected Time Path in Time-dependent Stochastic Networks where flow speeds of each link change statistically on each time interval. A solution method using the Kth-shortest Path algorithm is presented.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.493-496
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• 2004

The change of creep deformation mechanism due to the persistent change of stress conditions requires the constitutive relation for the analysis of long tenn behaviors considering age dependent material properties of concrete. In the present research, the process of time dependent behaviors in structure is divided into two stages; the non-mechanical deforming level which causes creep and shrinkage deformations, and the mechanical deforming level which causes mechanical deformations by the restraints of non-mechanical deformations due to internal or external factors. The incremental constitutive relation is derived by expanding the total stress-strain relation on the present time, with respect to the reference time using the Taylor series, and the modulus of elasticity in early ages of concrete was defined thru this process.

• Journal of Acupuncture Research
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• v.21 no.2
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• pp.167-181
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• 2004

Objective : Carthami Flos has been used as a herb to promote blood circulation to remove blood stasis in oriental medicine for many centuries. To investigate treatment of cerebral vascular disease(CVA) by promoting blood circulation and removing blood stasis(活血化瘀法), we observed the experimental Effects of Aqua-Acupuncture of Carthami Flos on the Regional Cerebral Blood Flow and Mean Arterial Blood Pressure in Rats. Method : When aqua-acupuncture of Carthami Flos(ACF) was injected into LI4, Liv3, B23, B62, GV16, experimental effects of ACF on the regional cerebral blood flow(rCBF) and mean arterial blood pressure(MABP) is not known. Therefor, this study was designed to investigate the effects of ACF on the change of cerebral hemodynamics. The changes of rCBF and MABP were tested by Laser Doppler Flowmetry(LDF). Results : When ACF was injected into LI4, change of rCBF and MABP were decreased in a injected time-dependent manner. When ACF was injected into Liv3, change of rCBF and MABP were decreased in a injected time-dependent manner. When ACF was injected into B23, change of rCBF was significantly increased in a injected time-dependent manner, MABP did not change. When ACF was injected into B62, change of rCBF was increased in a injected time-dependent manner, change of MABP was significantly decreased after injection 60min. When ACF was injected into GV16, change of rCBF and MABP were similar to the change of normal. Conclusions : In conclusion, I suggested that ACF(LI4, Liv3) has an effect that depress the blood pressure & cerebral hemodynamic acceleration and ACF(B23, B62) has an anti-ischemic effect through the improvement of crebral hemodynamics.

• The Korean Journal of Applied Statistics
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• v.35 no.1
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• pp.35-47
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• 2022

The receiver operating characteristic (ROC) curve was developed to quantify the classification ability of marker values (covariates) on the response variable and has been extended to survival data with diverse missing data structure. When survival data is understood as binary data (status of being alive or dead) at each time point, the ROC curve expressed at every time point results in time-dependent ROC curve and time-dependent area under curve (AUC). In particular, a follow-up study brings the change of cohort and incomplete data structures such as censoring and competing risk. In this paper, we review time-dependent ROC estimators under several contexts and perform simulation to check the performance of each estimators. We analyzed a dementia dataset to compare the prognostic power of markers.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.197-201
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• 2002

The healthy worker effect is an important issue in occupational epidemiology. We proposed a new statistical method to test the relationship between exposure and time to death in the presence of the healthy worker effect. In this study, we considered the healthy worker hire effect to operate as a confounder and the healthy worker survival effect to operate as a confounder and an intermediate variable. The basic idea of the proposed method reflects the length bias-sampling caused by changing one's employment status. Simulation studies were also carried out to compare the proposed method with the Cox proportional hazards models. According to our simulation studies, both the proposed test and the test based on the Cox model having the change of the employment status as a time-dependent covariate seem to be satisfactory at an upper 5% significance level. The Cox models, however, are inadequate with the change, if any, of the employment status as time-independent covariate. The proposed test is superior in power to the test based on the Cox model including the time-dependent employment status.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.906-909
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• 2005

In this study, the dynamic flying characteristics of the worn head sliders are investigated theoretically due to the change in head geometry caused by head and disk contact. The film shapes can be approximated as taper- truncated cycloidal-flat film. Two-dimensional time dependent modified Reynolds equation included molecular slip effect are formulated with neglected the roughness effect. The motion of head slider was assumed to have two degree of freedom in this work. Finite difference approximation with Newton Raphson iterative technique and the fourth order Runge-Kutta method were implemented to obtain the transient response of the slider head with various change in head geometry numerically and compared with the transient response of the IBM3380 type head slider. The simulation results show the film shape has affects significantly on the static and dynamic characteristic of slider head in magnetic storage systems.