Kwang-Ho Yang

New formulas for predicting audible noise from overhead HVAC lines using evolutionary computations

Audible noise (AN) produced by corona discharges from high voltage transmission lines is one of the more important considerations in line design. Therefore, line designers must predetermine the AN using prediction formulas. This paper presents the results of applying evolutionary computation techniques using AN data from lines throughout the world to develop new highly accurate formulas for predicting the A-weighted AN during heavy rain and stable rain from overhead AC lines. Calculated ANs using these new formulas and existing formulas are compared with measured data.

Electromagnetic interference from a three phase double circuit 765-kV test line

This paper presents the results of long-term electromagnetic interference (EMI) measurements on the bundle of 6 Cardinal conductors tested at Koreas Kochang 765-kV full-scale test line. The instrumentation and the most important features of the facilities are also described. This new 3-phase double circuit test line can be energized at line-to-line voltages up to 850 kV. The analysis of the data shows that the 6-Cardinal conductor bundle meets the radio and television interference guidelines of the Korea Electric Power Corporation (KEPCO).

Development of a New Personal Magnetic Field Exposure Estimation Method for Use in Epidemiological EMF Surveys among Children under 17 Years of Age

A number of scientific researches are currently being conducted on the potential health hazards of power frequency electric and magnetic field (EMF). There exists a non-objective and psychological belief that they are harmful, although no scientific and objective proof of such exists. This possible health risk from ELF magnetic field (MF) exposure, especially for children under 17 years of age, is currently one of Koreas most highly contested social issues. Therefore, to assess the magnetic field exposure levels of those children in their general living environments, the personal MF exposure levels of 436 subjects were measured for about 6 years using government funding. Using the measured database, estimation formulas were developed to predict personal MF exposure levels. These formulas can serve as valuable tools in estimating 24-hour personal MF exposure levels without directly measuring the exposure. Three types of estimation formulas were developed by applying evolutionary computation methods such as genetic algorithm (GA) and genetic programming (GP). After tuning the database, the final three formulas with the smallest estimation error were selected, where the target estimation error was approximately 0.03 μT. The seven parameters of each of these three formulas are gender (G), age (A), house type (H), house size (HS), distance between the subjects residence and a power line (RD), power line voltage class (KV), and the usage conditions of electric appliances (RULE).

Design of the DC ±500kV full scale transmission test line in Gochang

A HVDC test line that functions as a prototype variation was constructed in Korea, after considering the main functions and characteristics of diverse ±500kV DC transmission test line towers and the results of the analysis of the lines insulation, environment, fitting, transmission equipment, economic feasibility, and operational efficiency. The variable prototype test line has advantages in line-related researches, including in the fitting design, insulation coordination design, line construction technology and transmission equipment development, and does not require high-cost towers, unlike overseas test lines. The maximum applied voltage of the newly constructed DC test line was ±600 kV, and a measurement system was established around the line to evaluate the interference factors. Tests on various environmental characteristics will be performed to derive the optimal pole arrangement coordinates for the Korean environment, while changing the pole arrangement and height of the line using a large hoist installed at special arms in tower No. 2 and 3.

Occupational and residential personal exposures to magnetic field over 24-hour periods in Korea

The objective of this survey is to characterize personal magnetic field exposure of the general population in Korea. The participants of the survey on magnetic field exposure were selected randomly, by occupation. The participant wore the magnetic field meter for about 25-28 hours and the data were stored in the meter. In this first step survey, the number of participant is 244 and the second step, about 400 subjects is surveyed in the near future. The statistics of the 24-hour exposure data are the major concern of this survey. However the survey provided the opportunity to analyze exposures corresponding to different types of activities. It was analyzed by the separating periods of time corresponding to the following activities: entire 24-hour period, in bed, at work and by occupation. Therefore the database will be established to analyze the status of personal magnetic field exposure and safety.

Discussion of "New formulas for predicting audible noise from overhead HVAC lines using evolutionary computations" and closure

K. Tanabe and K. Miyajima comment on the paper by K.-H. Yang et al. (see ibid., vol.15, no.4, p.1243-51, 2000) and ask three questions of the authors. The original authors reply to the comments.