• Korean Security Journal
• /
• no.31
• /
• pp.47-71
• /
• 2012

This study is to analyse the effect on self-effectiveness of a course decision of duty stress in the college students related to guard major study. For this, the college students related to guard major study in Gwang-ju and Jeonnam region were selected as a universe at April 2011. And a sampling was practiced as a random sample. A question investigation was used in a entry method of self-estimation. Furthermore a total of 171 person(85.5%) was used as final analysis data. The collected data were employed in a statistics program of SPSS for win version 17.0. And used in a way of Pearson's interrelation analysis and Multiple Regression Analysis. The conclusion was as follows. Firstly, family surroundings stress and studies stress of duty stress affected beneficially statistically a goal selection of self-effectiveness of course decision. Family surroundings influenced upon it positively. And studies effected on it negatively. Secondly, all factors of duty stress didn't affect beneficially statistically the work information of self-effectiveness of course decision. Thirdly, school surroundings stress of duty stress influenced upon positively statistically the problem solution of self-effectiveness of course decision. Fourthly, personality stress and duty anxiety stress affected beneficially statistically the future plan of self-effectiveness of course decision. Personality influenced upon it negatively and duty anxiety affected it positively.

• Proceedings of the KIEE Conference
• /
• 2005.11b
• /
• pp.145-147
• /
• 2005

This paper presents a methodology for satisfying the thermal comfort of Indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. KEPCO(Korea Electric Power Corporation) use the fixed duty cycle control method regardless of the indoor thermal environment. This method has disadvantages that energy saying depends on the set-point value of the Air-Conditioner and DLC has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. A variable duty cycle estimates the PMV(Predict Mean Vote) at the next step with a predicted temperature and humidity coming from the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. The proposed methodology uses the historical real data of Sep. 7th, 2001 from a classroom in seoul to verify the effectiveness of the variable duty cycle method comparing with fixed duty cycle. The result shows that the variable duty cycle reduces the peak demand to 2.6times more than fixed duty cycle and increases the load control ratio by 8% more. Based on the variable duty cycle control algorithm, the effectiveness of DLC is much more improved as compared with the fixed duty cycle.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.55 no.10
• /
• pp.399-409
• /
• 2006

This paper presents a novel method for satisfying the thermal comfort of indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. Korea Electric Power Corporation (KEPCO) use the fixed duty cycle control method regardless of the indoor thermal environment. However, this method has disadvantages that energy saving depends on the set-point value of the Air-Conditioner and direct load control (DLC) has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. In this paper, the variable duty cycle control method is proposed in order to compensate the weakness of conventional fixed duty cycle control method and improve the satisfaction of residents and the reduction of peak demand. The proposed method estimates the predict mean vote (PMV) at the next step with predicted temperature and humidity using the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. To verify the effectiveness of the proposed variable duty cycle control method, the case study is performed using the historical data on Sep. 7th, 2001 acquired at a classroom in Seoul and the obtained results are compared with the fixed duty cycle control method.

• Journal of Applied Reliability
• /
• v.11 no.4
• /
• pp.433-445
• /
• 2011

Duty cycle is determined as the ratio of operating time to total time. Duty cycle in reliability prediction is one of the significant factors to be considered. In duty cycle application, non-operating time failure rate has been easily ignored even though the failure rate in non-operating period has not been proved to be small enough. Ignorance of non-operating time failure rate can result in over-estimated system reliability calculation. Furthermore, utilization of duty cycle in reliability prediction has not been evaluated in its effectiveness. In order to address these problems, two reliability models, such as MIL-HDBK-217F and RIAC-HDBK-217Plus, were used to analyze non-operating time failure rate. This research has proved that applying duty cycle in 217F model is not reasonable by the quantitative comparison and analysis.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.11a
• /
• pp.525-526
• /
• 2009

Due to the limitation of battery life time, energy is one of the most crucial issues for wireless sensor networks. Thus this paper proposes an energy efficient duty cycle scheme to conserve energy mostly. To handle the large varieties of data (i.e., both low and high traffic load) the proposed duty cycle scheme ensures a fair access period (FAP) and a prioritized access period (PAP). The idea presented in this paper able to reduce the collision probability and energy consumption. Finally simulation outputs have demonstrated the effectiveness of the proposed duty cycle task and showed a noticeable performance in terms of energy usage.

• Corrosion Science and Technology
• /
• v.6 no.2
• /
• pp.62-67
• /
• 2007

Several heavy duty coatings at an every kind industry facilities to various systems currently have been applied review to the many industry fields. Corrosion-protective characteristics in the case of novolac epoxy among them and unsaturated polyester have been applied most widely. epoxy and flake heavy duty coatings are applied for such reason in an every kind facilities(stack, FGD, cooler, chemical tank etc) of a fossil-fuel power plants Cases of the fossil-fuel power plants are exposed to more severe corrosion environment compared with other facilities and It is difficult to display the performance of long-term method at apply to be the partial. Our study shows fluoro-polymer composite coating method to overcome of the limit. The comparison did previous method and heavy duty coating about FGD plants most at a corrosion environment among fossil-fuel power plants. Additionally, other facilities examined different heavy duty method. The design mode of fluoro-polymer composite coating according to an every kind facilities show extensive methods that are characteristic revelation of film(top, middle and primer layer) composition of the paint, film thickness in accordance with a facilities corrosion and the corrosion protective effectiveness to come into being use fluoro-polymer composite with heavy duty paint(epoxy).

• Journal of Power Electronics
• /
• v.17 no.2
• /
• pp.368-379
• /
• 2017

In this paper, a direct torque control algorithm with novel duty cycle-based modulation is proposed for permanent magnet synchronous motor drives fed by neutral-point clamped three-level inverters. Compared with the standard DTC, the proposed algorithm can suppress steady-state torque ripples as well as ensure neutral-point potential balance and smooth vector switching. A unified torque/flux evaluation table with multiple voltage vectors and precise control levels is established and used in this method. This table can be used to evaluate the effects of duty-cycle vectors on torque and flux directly, and the elements of the table are independent of the motor parameters. Consequently, a high number of appropriate voltage vectors and their corresponding duty cycles can be selected as candidate vectors to reduce torque ripples by looking up the table. Furthermore, small vectors are incorporated into the table to ensure the neutral-point potential balance with the numerous candidate vectors. The feasibility and effectiveness of the proposed algorithm are verified by both simulations and experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.2
• /
• pp.102-109
• /
• 2013

In this paper, a new torque predictive control method of interior permanent magnet synchronous motor is developed based on an extended rotor flux. Also, a duty ratio prediction method is proposed and allows the duty ratio of the active stator voltage vector to be continuously calculated. The proposed method makes it possible to relatively reduce the torque ripple under the steady state as well as to remain the good dynamic response in the transient state. With the duty ratio prediction method, the magnitude and time interval of the active stator voltage vector applied can be continuously controlled against the varying operation conditions. This paper shows a comparative study among the switching table direct torque control(DTC), the SVM-DTC, conventional torque predictive control, and the proposed torque predictive control. Simulation results show validity and effectiveness of this work.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.23 no.1
• /
• pp.32-39
• /
• 2018

A new dc link voltage controller for a three-phase Vienna rectifier is proposed in this study. This method uses load current and duty information to control dc link voltage. The load current affects the capacitor current and varies the output voltage. Existing methods do not perfectly consider the load current. By considering load current with duty compensation in the proposed method, the transient response is improved by the load variation regardless of the input voltage. The effectiveness of the proposed method is compared with other control methods when the load changes rapidly using PSIM simulation and experiment.

• Journal of the military operations research society of Korea
• /
• v.9 no.1
• /
• pp.3-13
• /
• 1983

This thesis analyzes the behavior of Korean senior officers corroboratively. The subject of research is a group of senior officers who were graduated from the Korea Military Academies of three armed forces, promoted to colonel at their first screen, and served for the duration of active duty on 18-22 years. The study reviews a correlation between the academic record and military promotion, and also between it and the duration of active service. Tri-dimensional leader effectiveness model, which P. Horsey and K.H. Blanchard developed to analyze LEAD (lead effectiveness and adaptability description), is used to evaluate the basic leader behavior styles.