• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.1370-1376
• /
• 2015

Generally, an autotransformer(AT) feeding system consists of double tracks, up and down, with the trolley wire and feeder wire of the up and down tracks connected in the sectioning post(SP). Consequently, load current or fault current flows on two tracks based on catenary impedance characteristics, making it difficult to estimate catenary impedance accurately. This paper presents a technique for the estimation of catenary impedance using boosting current compensation based on the current division characteristics of an AT feeding system to improve the operation performance of impedance relay. To verify the technique, we model an AT feeding system through a power analysis program (PSCAD/EMTDC) and simulate various operation and fault conditions. Through the simulation, we confirmed that the proposed technique has estimated catenary impedance with a similar degree of accuracy to the actual catenary impedance

• The Journal of Engineering Geology
• /
• v.25 no.4
• /
• pp.525-532
• /
• 2015

After comparing the effectiveness of standoff compensation between current techniques using data obtained from a series of borehole model experiments for standoff compensation in 2007, 2008, and 2009, a follow-up study was conducted to find a more effective standoff compensation algorithm, Comparing the results of the application of the conventional spine and ribs technique, and the spine and ribs technique in terms of apparent density shows that the standoff compensation error obtained from the latter method is more than twice that obtained from the former. The larger size of the compensation error from the spine and ribs plot using the radioactive decay equation indicates that there are no benefits in using this equation in standoff compensation. Based on these results, we propose a reverse transform spine and ribs technique by essentially combining the conventional spine and ribs technique and the spine and ribs technique in terms of apparent density.

• International conference on construction engineering and project management
• /
• 2013.01a
• /
• pp.338-343
• /
• 2013

Integrated Project Delivery (IPD) as a delivery method fully capitalizes on an integrated project team that takes advantage of the knowledge of all team members to maximize project outcomes. IPD is currently the highest form of collaboration available because all three core project stakeholders, owner, designer and contractor, are aligned to the same purpose. Compared with traditional project delivery approaches such as Design-Bid-Build (DBB), Design-Build (DB), and CM at-Risk, IPD is distinguished in that it eliminates the adversarial nature of the business by encouraging transparency, open communication, honesty and collaboration among all project stakeholders. The team appropriately shares the project risk and reward. Sharing reward is easy, while it is hard to fairly share a failure. So the compensation structure and the contingency in IPD are very different from those in traditional delivery methods and they are expected to encourage motivation, inspiration and creativity of all project stakeholders to achieve project success. This paper investigates the compensation structure in IPD and provides a method to determine the proper level of contingency allocation to reduce the risk of cost overrun. It also proposes a method in which contingency could be used as a functional monetary incentive when established to produce the desired level of collaboration in IPD. Based on the compensation structure scenario discovered, a probabilistic contingency calculation model was created by evaluating the random nature of changes and various risk drivers. The model can be used by the IPD team to forecast the probability of the cost overrun and equip the IPD team with confidence to really enjoy the benefits of collaborative team work.

• Journal of Korean Academy of Nursing
• /
• v.47 no.4
• /
• pp.488-498
• /
• 2017

Purpose: The focus of the study was on the selection-optimization-compensation (SOC) strategy to predict successful aging mediated by dyspnea symptoms in older adults with chronic obstructive pulmonary disease. The model was constructed based on the hypotheses that coping strategy and social support of the elders predict successful aging through the SOC strategies. Methods: Participants were 218 outpatients with chronic obstructive pulmonary disease recruited for the study. Data collection was done from March 25 to September 11, 2015, and analyzed using SPSSWIN 22.0 and AMOS 21.0. Results: The hypothetical model appeared to be fit to the data. Seven of eight hypotheses selected for hypothetical model were statistically significant. The SOC strategy has only significant indirect effects through dyspnea symptoms on successful aging. Coping strategy, social support, SOC strategies and dyspnea symptoms explained 62% of variance in successful aging. Conclusion: The SOC strategies with social support and dyspnea symptoms significantly explained successful aging among patients with chronic obstructive pulmonary disease. Nursing strategies should be focused on social support and coping strategies to optimize SOC strategies so that older adults with chronic obstructive pulmonary disease are able to manage dyspnea symptoms and eventually achieve successful aging.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.375-379
• /
• 1997

Thermal drift of the machine tool spindle due to temperature increase dominates the major source of the machine tool error. To compensate the thermal errors, software based error correction methods could be implemented. In th~s case, we need model to map the relationship between temperature and thermal distortion. Traditionally, two or three different methods have been trled: step increase of spindle speed, constant, random. The latter two methods are described in the document of ISOlDIS230-3. In this research, three different methods were verified through the experiments from the viewpoint of compensation of thermal distortion. Constant spindle speed turned out good enough for monitoring the behavior of the thermal drift and modeling the relationship between temperature and thermal distortion.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.1
• /
• pp.29-37
• /
• 2012

A simple and effective dead time compensation scheme for a PWM inverter-fed permanent magnet synchronous motor (PMSM) drive using the model reference adaptive control (MRAC) and coordinate transformation is presented. The basic concept is to first transform a time-varying disturbance caused by the dead time and inverter nonlinearity into unknown constant or slowly-varying one by the coordinate transformation, and then use the MRAC design technique to estimate this parameter in the stationary reference frame. Since the MRAC scheme is a suitable way of estimating such a parameter, the control performance can be significantly improved as compared with the conventional observer-based method tracking time-varying parameters. In the proposed scheme, the disturbance voltage caused by the dead time is effectively estimated and compensated by on-line basis without any additional circuits nor existing disadvantages as in the conventional methods. The asymptotic stability is proved and the effectiveness of the proposed scheme is verified.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.261-261
• /
• 2000

This paper analyzes the characteristics of pre-sliding friction of an X-Y table of CNC machining center at velocity reversal, and presents a simple and effective method of friction compensation based on this characteristics. At velocity reversal, a large position tracking error occurs because of the discontinuous change of friction. The relationship between the occurrence time of maximum position tracking error and the acceleration at zero velocity is analyzed by using the spring-like friction model. Furthermore, the experimental observation verifies this relation. From this, the state transition tine from pre-sliding regime into sliding regime can be predicted. Using the predicted transition time, the friction can be effectively compensated and table experimental results show its effectiveness.

• Journal of the Semiconductor & Display Technology
• /
• v.3 no.2
• /
• pp.41-46
• /
• 2004

This paper proposes a robust discrete time Kalman filter (RDKF) for the dynamic compensation of nonlinearity in a homodyne laser interferometer for high-precision displacement measurement and in real-time. The interferometer system is modeled to reduce the calculation of the estimator. A regulator is applied to improve the robustness of the system. An estimator based on dynamic modeling and a zero regulator of the system was designed by the authors of this study. For real measurement, the experimental results show that the proposed interferometer system can be applied to high precision displacement measurement in real-time.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.2
• /
• pp.184-189
• /
• 2013

This paper proposes a method for improving the performance of a position sensorless control system for a slotless surface permanent magnet synchronous motor (SPMSM) in a very low-speed region. In position sensorless control based on a motor model, accurate motor parameters are required because parameter errors would affect position estimation accuracy. Therefore, online parameter identification is applied in the proposed system. The error between the reference voltage and the voltage applied to the motor is also affect position estimation accuracy and stability, thus it is compensated to ensure accuracy and stability of the sensorless control system. In this study, two voltage error compensation methods are used, and the effects of the compensation methods are discussed. The performance of the proposed sensorless control method is evaluated by experimental results.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.319-322
• /
• 2001

In this paper, a 3phase-3wire series active power filter compensating current harmonics and unbalanced source voltages is presented. The system is composed of series active power filter and shunt passive filters that are tuned 5th and 7th harmonics. In this system, series active power filter improves harmonic compensation characteristics of the shunt passive filters and compensates the unbalanced source voltages. In the proposed algorithm, compensation voltage for harmonic reduction is calculated by a performance function, and compensation voltage for the unbalanced source voltage is calculated in based on the synchronous reference frame. Some results obtained from the experimental model using the proposed method are presented to demonstrate and confirm its validity.