• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2005.05a
• /
• pp.74-77
• /
• 2005

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, voltage unbalance is generated at the user's 3-phase 4-wire distribution systems with single & three phase. Voltage unbalance is mainly affected by load system rather than power system. Unbalanced voltage will draws a highly unbalanced current and results in the temperature rise and the low output characteristics at the machine. It is necessary to analyse correct voltage unbalance factor for reduction of side effects in the industrial sites. Voltage unbalance is usually defined by the maximum percent deviation of voltages from their average value, by the method of symmetrical components or by the expression in a more user-friendly form which requires only the three line voltage readings. If the neutral point is moved at the 3-phase 4-wire system by the unbalanced load, by the conventional analytical method, line and phase voltage unbalance leads to different results due to zero-sequence component. This paper presents a new analytical method for phase and line voltage unbalance factor in 4-wire systems. Two methods indicate exact results.

• Journal of Environmental Impact Assessment
• /
• v.23 no.3
• /
• pp.169-176
• /
• 2014

The purpose of this study is to estimate the vibration reduction effect of the borehole which is controlled the vibration propagation in the ground. For this study, we measured the vibration velocity before and after the borehole installation. The results are as follows: The peak particle velocity(PPV) and peak vector sum(PVS) was reduced by the borehole. And also, the deviation of vibration velocity before and after the borehole installation showed large values in longitudinal and vertical component depending on the receive distance, and increased depending on the size of vibration energy. Finally, the vibration isolation efficiency was 25~35 percentage at 1.5m receive distance, and was 4~14 percentage at 3.0m receive distance. It was found that the vibration isolation efficiency was good in small vibration energy, but was not good at long receive distance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.5
• /
• pp.118-125
• /
• 2003

This paper presents a scheme for the placement of dispersed generator systems(DGs) based on load model in unbalanced systems. Groups of each individual load model consist of residential, industrial, commercial, official and agricultural load The main idea of solving fuzzy goal programming is to transform the original objective function and constraints into the equivalent multi-objectives functions with fuzzy sets to evaluate their imprecise nature for the criterion of power loss minimization, the number or total capacity of DGs and the bus voltage deviation, and then solve the problem using genetic algorithm The method proposed is applied to IEEE 13 bus unbalanced distribution systems to demonstrate its effectiveness.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.14 no.4
• /
• pp.39-47
• /
• 2000

This paper presents the sinusoidal tracking controller in error to eliminate the steady state control error and to improve the transient characteristics for input current in voltage source PWM converter with input current estimation. The estimation method of input current values and configuration of controller are described. DC output voltage is controlled by PI controller, and sinusoidal tracking current controller which tracks directly AC input current is used as input current controller. The sinusoidal tracking current controller can be used without any coordinate transformation algorithms.It is proved that the steady state deviation of input current reduces to zero and the proposed control system is not affected by input voltage from transfer functions of input current control system. The validity of proposed scheme is verified by simulations and experimental results for load resister and input voltage variation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.8
• /
• pp.15-20
• /
• 2010

This paper shows a reasonable diversity factor, that was made by the systematic and statistical way considering actual conditions, such as investigated contract power and peak power for the last 5 years of each customer for 20 Lease Apartment. In this paper, it is necessary to analyze the key features and general trend from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum, minimun and thus it was carried out by the linear and nonlinear regression analysis. The standards of demand, diversity, and load density are necessary to create the design of a transformer capacity that is seldom presented in terms for academic study.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.267-269
• /
• 2009

In this paper, insulations characteristics by temperature changes($+10{\sim}-60[^{\circ}C]$) of $SF_6$ 9as in the experimental chamber were studied. From this result, The breakdown characteristics classify the gas & liquid coexisted stage of voltage value increases & much deviation and the $V_B$ low stage as the interior of chamber gets filled with mixture of $SF_6$ that are not liquefacted and remaining air which couldn't be ventilated. In addition the ability of insulation of liquid $SF_6$ was higher than that of the highly pressurized $SF_6$ gas. In this research, we want to provide the base data on designing insulation of high-temperature superconductor and the cryogenic equipments by investigating the insulation characteristics of $SF_6$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.6
• /
• pp.85-88
• /
• 2009

This paper shows a reasonable power density, that was made by the systematic and statistical way considering actual conditions, such as investigated power consumption capacity for the year and peak power, contract power for the last 5 years of each customer for 23 general customers all data obtained by AMR. In this dissertation, it is necessary to analyze the key features from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum, minimun and load factor.

• Journal of the Korean Society of Safety
• /
• v.31 no.6
• /
• pp.25-31
• /
• 2016

This paper has analyzed the structure, applicable regulations and the resistance characteristics of insulation ring type of CSST (Corrugated Stainless Steel Tubing for Gas). With the flammability test conducted in accordance with KS C IEC 60811-1-1, the evaluation of insulation resistance, temperature characteristics, and reliability has been conducted. An insulation ring type CSST consists of protective coating, tube, nut, insulation ring, packing, socket, and ball valve. Connecting an insulation ring type CSST to gas tubings for gas appliance is not permitted, moreover, the product shall be installed inside a sleeve pipe in case of buried installation such as the ceiling. Damages on protective coating and tube were detected when fire was applied to the test sample with a portable torch for 60 seconds. The insulation resistance of a normal product was $49.59M{\Omega}$, while that of the product completed the flammability test reduced to $9.21M{\Omega}$. The mean insulation resistance within the confidence Interval of 95% using the mini tap program 17 was $49.59M{\Omega}$ and the mean insulation resistance within the confidence interval reduced to $9.21M{\Omega}$. In the normal distribution analysis of 95% confidence interval, the value-P of the normal product was stable at 0.075 and AD(Anderson-Darling) statistic value was turned out to be 0.063, which is very normal, and the standard deviation was analyzed as 0.2586. The value P of the product completed the flammability test resulted in 0.005, the AD was 1.355 and the standard deviation reduced to 0.07908.

• Korean Journal of Agricultural Science
• /
• v.41 no.4
• /
• pp.473-480
• /
• 2014

Upon setting up a dedicated plastic greenhouse for tomato cultivation developed by the Rural Development Administration on the Gyehwa reclaimed land, this study was aimed at analyzing the problems can be occurred in the installation of plastic greenhouse on reclaimed lands as well as finding out solutions for improvement. A relatively cheaper wooden pile was used in the installation in order to supplement the soft ground conditions. Based on the results of ground investigation of the installation site, both the allowable bearing capacity and pulling resistance of the wooden pile with a diameter of 150 mm and a length of 10 m were computed and came out to be 30.645 kN. It was determined that the values were enough to withstand the maximum compressive force (17.206 kN) and the pullout force (20.435 kN) that are generally applied to the greenhouse footing. There are three problems aroused in the process of greenhouse installation, and the corresponding countermeasures are as follow. First, due to the slightly bent shape of the wooden pile, there were phenomenon such as deviation, torsion, and fracture when driving the pile. This could be prevented by the use of the backhoe (0.2) rotating tongs, which are holding the pile, to drive the pile while pushing to the direction of the driving and fixing it until 5 m below ground and applying a soft vibrating pressure until the first 2 m. Second, there exists a concrete independent footing between the column of the greenhouse and the wooden pile driven to the underground water level. Since it is difficult to accurately drive the pile on this independent footing, the problem of footing baseplate used to fix the column being off the independent footing was occurred. In order to handle with this matter, the diameter of the independent footing was changed from 200 mm to 300 mm. Last, after films were covered in the condition that the reinforcing frame and bracing are not installed, there was a phenomenon of columns being pushed away by the strong wind to the maximum of $11m{\cdot}s^{-1}$. It is encouraged to avoid constructions in winter, and the film covering jobs always to be done after the frame construction is completely over. The height of the independent footing was measured for 9 months after the completion of the greenhouse installation, and it was found to be within the margin of error meaning that there was no subsidence. The extent to the framework distortion and the value of inclinometers as well showed not much alteration. In other words, the wooden pile was designed to have a sufficient bearing capacity.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.2
• /
• pp.245-250
• /
• 2017

From the instant of installation and operation, power cables start deteriorating. Cable systems can be maintained not only by monitoring the insulation status of the insulation layer and oversheath, but also the insulation status of the terminal and junction in high-voltage power cables. When the cable system (the cable itself and cable junctions combined) deteriorates, fire accidents happen due to dielectric breakdowns. We have invented a device to monitor the deteriorating status of cables, and installed it at Korea Western Power Co. Ltd. located in Taean, Chungcheongnam-do Province. In this paper, we present the results obtained using our device, through analysing and calculating the standard deviation of leakage current from cable insulators attached to the cables. When the standard deviation of analysed leakage current falls below a critical value, a cable system is deemed to be operating safely. But when the standard deviation of analysed leakage current is larger than the critical value, the insulation status of the terminal and junction in the cable system is considered to have seriously deteriorated. The terminal and junction in the relevant system should then be replaced preemptively in order to prevent blackout accidents of cables caused by the suspension of power supply.