• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.232-239
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• 2013

This paper proposes an improved stator flux estimator through ensuring conventional PLPF to act as a pure integrator for sensorless control of induction motors. Conventional PLPF uses the estimated synchronous speed as a cut-off frequency and has the gain and phase compensators. The gain and phase compensators are determined on the assumption that the estimated synchronous angular speed is coincident with the real speed. Therefore, if the synchronous angular speed is not same as the real speed, the gain and phase compensation will not be appropriate. To overcome the problem of conventional PLPF, this paper analyzes the relationship between the synchronous speed error and the phase lag error of the stator flux. Based on the analysis, this paper proposes the synchronous speed error compensation scheme. To achieve a start-up without speed sensor, the current model is used as the stator flux estimator at the standstill. When the motor starts up, the current model should be switched into the voltage model. So a stable transition between the voltage model and the current model is required. This paper proposes the simple transition method which determines the initial values of the voltage model and the current model at the transition moment. The validity of the proposed schemes is proved through the simulation results and the experimental results.

• The Korean Journal of Applied Statistics
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• v.27 no.2
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• pp.317-330
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• 2014

Bipolar disorder is a psychopathy characterized by manic and major depressive episodes. It is important to determine the degree of depression when treating patients with bipolar disorder because 810% of bipolar patients commit suicide during the periods in which they experience major depressive episodes. The Hamilton depression rating scale is most commonly used to estimate the degree of depression in a patient. This paper proposes using the Hamilton depression rating scale to estimate the effectiveness of patient treatment based on the linear mixed effects model and the transition model. Study subjects were recruited from the Seoul National University Bundang Hospital who scored 8 points or above in the Hamilton depression rating scale on their first medical examination. The linear mixed effects model and the transition model were fitted using the Hamilton depression rating scales measured at the baseline, six month, and twelve month follow-ups. Then, Hamilton depression rating scale at the twenty-four month follow-up was predicted using these models. The prediction models were then evaluated by comparing the observed and predicted Hamilton depression rating scales on the twenty-four month follow-up.

• Korean journal of communication and information
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• v.21
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• pp.63-86
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• 2003

Digital TV is expected to usher in a new era of TV. Thanks to digital and network technologies, TV will no more be a dumb terminal as it is today. It will incorprate the computer and thus become an intelligent device which serves not only high quality broadcast programming, but a variety of information services much like the current networked-computer. However, the real world picture of digital TV is clearly different from such a rosy vision. Albeit too early to tell, the cases in Europe and the US attest that the digital transition suffers a setback in terms of technology, policy, business, marketing, and the users. As such, the digital transition is generally problematized in terms of policy, business model, marketing strategy, and so on. Comparatively speaking, the issues of technology, policy, business and marketing are not so complicated than that of digital TV users because of the cultural issues involved in the adoption of digital TV. In other words, the technological transition to digital TV is far easier than its cultural transition. The cultural transition demands policy makers and industries of different approaches to successfully facilitating the digital transition.

• Advances in concrete construction
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• v.8 no.3
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• pp.173-185
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• 2019

This article presents a comparative study of the effect of steel layouts on the seismic behavior of transition steel-concrete composite connections, both experimental and analytical investigations of concrete filled steel tube-reinforced concrete (CFST-RC) and steel reinforecd concrete-reinforced concrete (SRC-RC) structures were conducted. The steel-concrete composite connections were subjected to combined constant axial load and lateral cyclic displacements. Tests were carried out on four full-scale connections extracted from a real project engineering with different levels of axial force. The effect of steel layouts on the mechanical behavior of the transition connections was evaluated by failure modes, hysteretic behavior, backbone curves, displacement ductility, energy dissipation capacity and stiffness degradation. Test results showed that different steel layouts led to significantly different failure modes. For CFST-RC transition specimens, the circular cracks of the concrete at the RC column base was followed by steel yielding at the bottom of the CFST column. While uncoordinated deformation could be observed between SRC and RC columns in SRC-RC transition specimens, the crushing and peeling damage of unconfined concrete at the SRC column base was more serious. The existences of I-shape steel and steel tube avoided the pinching phenomenon on the hysteresis curve, which was different from the hysteresis curve of the general reinforced concrete column. The hysteresis loops were spindle-shaped, indicating excellent seismic performance for these transition composite connections. The average values of equivalent viscous damping coefficients of the four specimens are 0.123, 0.186 and 0.304 corresponding to the yielding point, peak point and ultimate point, respectively. Those values demonstrate that the transition steel-concrete composite connections have great energy dissipating capacity. Based on the experimental research, a high-fidelity ABAQUS model was established to further study the influence of concrete strength, steel grade and longitudinal reinforcement ratio on the mechanical behavior of transition composite connections.

• Journal of Aerospace System Engineering
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• v.1 no.2
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• pp.6-12
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• 2007

Flight modes of automatic flight control system for light general aviation flight deck. Garmin G1000, were realized using Stateflow. In developing aircraft, it is difficult to verify the operational flight program in particular branch statement because developer can not see any visual logical steam. So, Stateflow has been used to visualize logical stream, transition from one flight mode to another flight mode. The performance was approved by applying flight mode transition conditions of G1000 to proposed transition system that is composed of states, switches, events, data and transition conditions. DURMI-II was used as 6-DOF simulation model.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.219-226
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• 1996

A two-step approach has been used to obtain a new transition criterion for the stratified and nonstratified flow in horizontal pipe: (1) In the first step, a more general expression than the existing models for the flow transition criterion has been derived from the analysis of singular points and neutral stability conditions, or the parallel lines conditions of the transient one-dimensional two- phase flow equations of two-fluid model. (2) In the second step, introducing simplifications and incorporating a parameter into the general expression obtained in the first step to satisfy a number of physical conditions a priori specified, a new simple flow transition criterion for horizontal pipes has been derived. Comparison between results predicted by the present theory with the experimental data and theories in the pipe flow conditions, show good agreement.

• Journal of Navigation and Port Research
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• v.28 no.7
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• pp.587-591
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• 2004

In order to measure the performance of resources in a port container terminal, we conducted a state transition network simulation to model various equipment processes. The processes that container cranes and transfer cranes perform are idle, wait, move, and work. Vehicles perform idle, wait, empty travel, and full travel. Because cranes, vehicles, and vessels are movable entities and all equipment is classified as either a customer or server, we separated the various stages of the process based upon the state transition network To validate the simulation results, a real system was used to illustrate the use of various measurements using the state transition network.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1326-1334
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• 2000

The oscillatory excitation with a Strouhal number of 2.65 ncar the stagnation zone of hemispherical nose model was employed to control the laminar separation bubble and the transition to turbulence. The effects of oscillatory excitation upon the separation bubble and the transition were addressed in terms of kurtosis/skewness and time-frequency analyses. The measured noise spectrum of radiated sound from the turbulent boundary layer on the axi-symmetric infinite cylinder is compared with that by Sevik's wave-number white approximations. The noise sources in TBL on axi-symmetric cylinder and the caling of their far-field sound are also discussed.

• The Korean Journal of Applied Statistics
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• v.24 no.4
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• pp.709-719
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• 2011

We investigate the latent stage-sequential patterns of drinking behaviors of U.S. adolescents who have started to drink by age 14 years (seven years before the legal drinking age). A multiple-group latent transition analysis(LTA) with logistic regression is employed to identify the subsequent patterns of drinking behaviors among early-onset drinkers. A sample of 1407 early-onset adolescents from the National Longitudinal Survey of Youth(NLSY97) is analyzed using maximum-likelihood estimation. The analysis demonstrates that early-onset adolescents' drinking behaviors can be represented by four latent classes and their prevalence and transition are influenced by demographic factors of gender, age, and race.

• Korean Journal of Adult Nursing
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• v.21 no.4
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• pp.391-402
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• 2009

Purpose: This study was conducted to identify predictors of the stage of change for smoking cessation of male university students on the basis of the Transtheoretical model (TTM). Methods: The 388 current smokers or exsmokers who agreed to participate were recruited from three areas in Korea from August 2 to September 5, 2006. Data was analyzed using a SPSS program for descriptive statistics, ANOVA, and multiple logistic regression. Results: Most subjects (76.8%) were current smokers. According to stages of change, there were statistically significant differences in self efficacy, smoking temptation, decisional balance (cons, pros), and processes of change. The predictors of transition from contemplation to preparation were behavioral and experiential processes. The predictors of transition from preparation to action were pros of smoking and experiential process. The predictors of transition from action to maintenance were cons of smoking and behavioral process. Conclusion: Specific nursing interventions based on stages of change need to be developed for smoking cessation of male university students.