• International Journal of Aeronautical and Space Sciences
• /
• v.11 no.3
• /
• pp.201-205
• /
• 2010

DC/DC Switching power converters are commonly used to generate regulated DC output voltages with high-power efficiencies from different DC input sources. A switching converter utilizes one or more energy storage elements such as capacitors, or transformers to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter studied here consists of a power metal-oxide semiconductor field effect transistor switch, an inductor, a capacitor, a diode, and a pulse-width modulation circuit with oscillator, amplifier, and comparator. A buck converter containing a switched-mode power supply is also studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by simulation program with integrated circuit emphasis (SPICE). Furthermore, power efficiency was analyzed based on the specifications of each component.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.20-25
• /
• 2011

This paper analyzed the application of Superconducting Fault Current Limiter (SFCL) on 22.9 [kV] bus tie in a power distribution system. Commonly, the parallel operations of power main transformers offer a lot of merits. However, when a fault occurs in the parallel operation of power main transformer, the fault currents might exceed the interruption capacity of existing protective devices. To resolve this problem, thus, the SFCL has been studied as the fascinating device. In case that, Particularly, the SFCL could be installed to parallel operation of various power main transformers in power distribution system of the Korea Electric Power Corporation (KEPCO) on 22.9 [kV] bus tie, the effect of the resistance of SFCL could reduce the increased fault currents and meet the interruption capacity of existing protective devices by them. Therefore, we analyzed the effect of application and proposed the proper impedance of the R-type SFCL on 22.9 [kV] bus tie in a power distribution system using PSCAD/EMTDC.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.5
• /
• pp.342-348
• /
• 2021

The PV module of solar power systems requires maximum power point tracking (MPPT) technique because the power-voltage and current-voltage characteristics vary depending on the surrounding environment. In addition, the 120 Hz ripple voltage on the DC-Link is caused by the imbalance of the system voltage and current. The effect of this 120 Hz ripple voltage reduces the efficiency of the power generation system by increasing the output current distortion rate. Increasing the capacity of DC-Link can reduce the 120 Hz ripple voltage, but this method is inefficient in price and size. We propose a technique that detects 120 Hz ripple voltage and reduces the effect of ripple voltage without increasing the DC-Link capacity through a controller. The proposed technique was verified through simulations and experiments using a 1 kW single-phase solar power system. In addition, the proposed technique's feasibility was demonstrated by reducing the distortion rate of the output current.

• Proceedings of the IEEK Conference
• /
• 2000.06a
• /
• pp.209-212
• /
• 2000

In this paper, effect of imperfect power control on performance of a pseudonoise (PN) code tracking loop is analyzed and simulated for a direct-sequence/code-division multiple access (DS/CDMA) system. The multipath fading channel is modeled as a two-ray Rayleigh fading model. Power control error is modeled as a log-normally distributed random variable. The tracking performance of DLL (delay-locked-loop) is evaluated in terms of tracking jitter and mean-time-to-lose-lock (MTLL). From the simulation results, it is shown that the PN tracking performance is very sensitive to the power control error.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.7 no.1
• /
• pp.35-44
• /
• 2017

In this paper, we attempt to investigate the moderating effect of brand power on the effect of in-flight service quality on customer satisfaction and recommendation in the aviation industry. The results were as follows. First, in the case of high brand power FSC(full service carriers), the cost-to-benefit ratio as well as all other flight service properties influence to customer satisfaction. However, in the case of low brand power FSC, the cost-to-benefit ratio showed a greater impact of customer satisfaction compared to other in-flight services. Second, as in the case of customer satisfaction, while the cost-to-benefit ratio more influence to customer recommendation than other in-flight services in low brand power FSC, the cost-to-benefit ratio as well as all other flight service properties influence to customer recommendation together in high brand power FSC. Therefore, low brand power FSC required tit-for-tat strategy against to LCC(low cost carriers) by pursuing disruptive innovation for price. And high brand power FSC required sustaining innovation strategy through improving flight services.

• Journal of the Korean Wood Science and Technology
• /
• v.48 no.6
• /
• pp.869-877
• /
• 2020

The power consumption in the low consistency (LC) refining is an important indicator for the optimal control of the process and it is composed of the net power and the no-load power. The refining efficiency and process characterization of LC refining are directly affected by power consumption. In this paper, the effect of pulp consistency and average fiber length on the power consumption and refining efficiency were studied through the LC refining trials conducted by an experimental disc refiner. It is found that the curve of power-gap clearance can be divided into constant power section, power reduction section, and power increase section. And the no-load power and the adjustable domain of loading applied by the refining plates will increase as the increase of pulp consistency, while the increase of net power is larger than that of no-load power which makes the increasing of refining efficiency. Meanwhile, the adjustable domain of loading applied by the refining plates can be slightly improved by increasing the average fiber length, but its effect on the no-load power in the LC refining process can be neglected. The study of power consumption in LC refining is of positive significance for the proper selection of pulp properties in LC refining, in-depth exploration of refining mechanism, and energy consumption reduction in refining.

• Journal of the Korea Safety Management & Science
• /
• v.24 no.3
• /
• pp.55-60
• /
• 2022

The effect of motion taping on the grasping power of the wrist is investigated and here Based on the data obtained from the This study was conducted to provide a theoretical background for the study. Motion taping was performed on the wrist for middle-aged people between 50s and 60s, and the change in wrist gripping power through an electronic dynamometer was tested. According to the wrist grip test results, it was investigated that the application of motion taping has a great effect on the gripping power of the wrist. It is hoped that motion taping will be a tool to reduce musculoskeletal industrial accidents, and it will be helpful to improve the quality of life of workers by reducing the labor intensity or softening the wrist through motion taping.

• Journal of East Asia Management
• /
• v.3 no.1
• /
• pp.25-40
• /
• 2022

This study investigates the effect of labor union and its power on information opacity. Given that the information opacity ultimately leads to the stock price crash, this study examines the relationship between labor unions and future stock price crash risk. Further, by assuming a strike by labor union as the actual power of the unionization in firms, whether labor union's power subrogated by the activity (i.e., a strike) makes a significant difference in the likelihood of future stock price crash between unionized firms is also examined. The work place survey data provided by Korea Labor Institute is used to test the hypotheses. The data is for the periods of 2004 - 2012 on firms listed on Korea Stock Exchange and KOSDAQ. The results show that while labor unionization has a positive impact on future stock price crash risk, on which labor union's power has a negative impact. This means that the existence of labor union itself might facilitate firm's information to be opaque by tolerating manager opportunism, while its power mitigates the managerial opportunism, which leads to lower future stock price crash risk. This study adds to the literature on the role of labor unions as nonfinancial stakeholders and its power in accounting environment, and also on the determinants of stock price crash. It is also valuable to examine the unions' role in terms of the economic consequences of both presence and power of the labor unions.

• Journal of IKEEE
• /
• v.20 no.2
• /
• pp.163-166
• /
• 2016

It is important to operate the driving circuit under the optimal condition through precisely sensing the power consumption causing the temperature made mainly by the MOSFET (metal-oxide semiconductor field-effect transistor) when a BLDC (Brushless Direct Current) motor operates. In this letter, a Super-junction (SJ) power TMOSFET (trench metal-oxide semiconductor field-effect transistor) with an ultra-low specific on-resistance of $0.96m{\Omega}{\cdot}cm^2$ under the same break down voltage of 100 V is designed by using of the SILVACO TCAD 2D device simulator, Atlas, while the specific on-resistance of the traditional power MOSFET has tens of $m{\Omega}{\cdot}cm^2$, which makes the higher power consumption. The SPICE simulation for measuring the power distribution of 25 cells for a chip is carried out, in which a unit cell is a SJ Power TMOSFET with resistor arrays. In addition, the power consumption for each unit cell of SJ Power TMOSFET, considering the number, pattern and position of bonding, is computed and the power distribution for an ANSYS model is obtained, and the SJ Power TMOSFET is designed to make the power of the chip distributed uniformly to guarantee it's reliability.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.2
• /
• pp.262-270
• /
• 2013

A boundary protection method for power distribution line based on equivalent boundary effect is presented in this paper. In the proposed scheme, the equivalent resonance component with a certain central frequency is sleeve-mounted at the beginning of protected zone. The 'Line Boundary' is built by using boundary effect, which is created by introducing impedance in the primary-side of line. The 'Line Boundary' is significantly different from line wave impedance. Therefore, the boundary protection principle can be applied to power distribution line without line traps. To analyze the frequency characteristic corresponding to traveling-waves of introducing impedance in the primary-side of line, distributed parameters model of equivalent resonance component is established. The results of PSCAD/EMTDC simulation prove the obvious difference of voltage high frequency component between internal faults and external faults due to equivalent resonance component, and validate the scheme.