• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.495-498
• /
• 2001

The distribution line through which electricity is supplied from substation to customer generally varies by underground line and overhead line. In contrast that the underground line is shielded, the overhead lines do not have the shield layer. To overcome this weak point of the overhead lines, the aerial bundled cable(ABC) connection systems have been developed. The basic concept of the ABC connection system is the application of the underground cable system containing complete shield layer to the overhead cable system. The ABC system is the innovative technologies which enable the prevention of electric shocks, reduction of the maintenance charge and damage of the cable. This paper give a full detail of vertical connection system applied within a country.

• Journal of KSNVE
• /
• v.9 no.5
• /
• pp.899-905
• /
• 1999

Construction equipment noise has caused much annoyance for a number of dwellers in nearby construction field and has become a very serious issure in our living environment. Therefore, in our country, a practical solution and a better method of reducing construction equipment noise are highly required in construction field. Practical solutions for the construction equipment noise, however, are very difficult because of the poorness of basic data and insufficiency of the existing research. Especially, in order to establish the sound insulation plan about pilling works noise with high sound pressure level and impactive, a real situation of sound characteristics about the noise of pilling works in foundation work demands more detail investigation. In this point, this study attempts to survey the characteristics of attenuation and propagation of construction equipment noise in pilling work using SIP(soil-cement injected precast pile) method with casing. And this study intends to get the basic data for establishment of a standard about construction noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.292-295
• /
• 2006

Dimension and capacity of the zero tail type mini excavator are small as compared with medium or large excavators. Therefore, problems of the noise and the heat are major issues in design due to layout of each component such as the engine and the hydraulic module. It is necessary to reduce the noise and the vibration of construction machine, due to be enforced regulation for high noise construction machinery in the world. The objective of this study is to provide basic data which is apply to predict noise effect in detail design stage by estimating noise of cabin for zero tail type mini excavator.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.35 no.1
• /
• pp.36-43
• /
• 1986

Superconducting magnet can be employed in many fields, such as, magnet for strong field, superconducting rotating machine and superconducting energy storage system. In this paper, the solenoid magnet design procedure and materials used in construction are described in detail, and those are the fundamentals of superconducting magnet study. The fabrication and test procedure of 3 Tesla superconduting magnet are also described. Nb-Ti is used as a superconducting wire, GFRP and Kapton are used for electrical insulation. Inner diameter of the magnet is 10 cm. According to the test results, the field at the central point of the magnet was 3 Tesla, evaporation rate per hour was 2.7 litter and current at that case was 315 A.

• Proceedings of the KIEE Conference
• /
• 2003.11a
• /
• pp.392-395
• /
• 2003

The study of electric field analyses has been conducted on two kinds of bushings for 17.5kV $SF_6$ gas insulated recloser. In this paper, two model bushings and input conditions for the analyses are described in detail. The results of the electric field analyses are presented and compared with to find out the better design in two bushings. Finally some suggestions are given for improving the insulation characteristics of the bushings.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1644-1646
• /
• 2003

This paper presents recent studies on the on-line insulation monitoring and diagnostic systems for transformers developed by HHI. Sufficiently high sensitivity and accuracy for practical use were achieved for the system, combined with communication networks to provide an on-line remote monitoring system. Several alarm criteria are formulated to enable a superimposed monitoring system to perform decisive action. The reasons for monitoring the condition and maintaining the health of electrical apparatus were discussed. The experience at the fields and the criteria for the judgment are also discussed in detail.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.6
• /
• pp.49-57
• /
• 2015

This paper presents the discharge characteristics and economic feasibility of a Dry $Air/O_2$ and a $N_2/O_2$ mixture gas in order to review $SF_6$ alternative. From AC discharge experiment in an quasi-uniform field, it was found that the optimal $N_2/O_2$ mixing ratio which breakdown voltage and surface flashover voltage were the highest was 70/30 and that the pressure dependence on the breakdown voltage was higher than that of the surface flashover voltage in the Dry $Air/O_2$ and the $N_2/O_2$ mixture gas. The mixing ratio (70/30) and the tendency of the pressure dependence were described in detail based on physical factors (impact ionization coefficient, electron attachment coefficient, secondary electron emission coefficient) involved in discharge mechanism and a electron source, respectively. In addition, the performance insulation and the economic feasibility of the Dry $Air/O_2$ and the $N_2/O_2$ mixture gas were discussed so that Dry $Air/O_2$ mixture gaswas more suitable than $N_2/O_2$ mixture gas to the $SF_6$ alternative.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.32 no.4
• /
• pp.401-409
• /
• 2012

Ultrasonic testing are far superior to other nondestructive tests for detecting the disbond interface which occurred in adhesive interface. However, a solid rocket motor consisting of a steel case, rubber insulation, liner, and propellant poses many difficulties for analyzing ultrasonic waves because of the superposition of reflected waves and large differences in acoustic impedance of various materials. Therefore, ultrasonic tests for detecting the disbond interface in solid rocket motor have been applied in very limited areas between the steel case and rubber insulation using an automatic C-scan system. The existing ultrasonic test cannot detect the disbond interface between the liner and propellant of a solid rocket motor because most of the ultrasonic waves are absorbed in the rubber material which has low acoustic impedance. This problem could be overcome by analyzing the resonance frequency from the frequency spectrum using the ultrasonic resonance method. In this paper, a new technique to detect the disbond interface between the liner and propellant using ultrasonic resonance characteristics is discussed in detail.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.4 no.1
• /
• pp.27-39
• /
• 1967

The fabrication of the barium titanate ceramic capcitors has been studied. The effects of the impurities for alumina and silica upon mechanical and electrical characteristics have been examined in detail. The preparation of equimolar titanium oxide and barium carbide in addition two percent of alumina and point two five perdcent of silica has shown the best results. This is fired up to thirteen hundred degrees Celsius with the rate of two hundred degrees Celsius per hour and soaked three hous at this temperature. The dielectric constant of this sample is approximately equal with the standard and theoretical values at room temperature. The insulation resitances of the most fabricated capacitors are in the order of twenty thousand megohms, the dielectric constant and the dissipation factor are almost flat up to just below of curie temperature, and the porosities of the most ceramics are less than point one percent and well close or equal to zero percent.

• Journal of the Korean Society of Safety
• /
• v.29 no.6
• /
• pp.137-143
• /
• 2014

Asbestos is given to a variety of six naturally occurring silicate minerals. These minerals possess high tensile strength, flexibility, resistance to chemical and thermal degradation, and electrical resistance. These minerals have been used for decades in thousands of commercial products, such as insulation and fireproofing materials, automotive brakes, textile products, cement and wallboard materials. When handled, asbestos can separate into microscopic-size particles that remain in the air and are easily inhaled. It is now known that prolonged inhalation of asbestos fibers can cause serious and fatal illnesses including malignant lung cancer, mesothelioma, and asbestosis. Therefore the use of asbestos and asbestos products has dramatically decreased in recent years. Also all constructions including asbestos should be removed under strictly controlled conditions and very tightly implemented health & safety management systems. In this study, the process of the removal work of the asbestos cement slate was analyzed by IDEF-0 modeling and evaluated by 4M risk assessment method. The results show that removal work of the asbestos cement slate was classified five process and eighteen detail process. The risk of safety side the higher than the risk of health side in 4M risk assessment.