• Progress in Superconductivity
• /
• v.6 no.2
• /
• pp.113-117
• /
• 2005

In this study, electromagnetic analysis of current paths including meander pattern, spiral pattern, and bi-spiral pattern were performed and in order to verity the analysis results, experiments tests including quench test, and insulation tests were performed. In addition, bubble corner concepts were introduced to enhance insulation reliability. From our study, bi-spiral pattern of YBCO thin films were rather effective for quench and insulation than the other patterns. So this current path pattern was adopted for YBCO thin films in order to develop 6.6 kV resistive fault current limiters. Finally YBCO thin films were connected in series and parallel to enhance capacity, and the test results of current limiting characteristics of 6.6kV resistive SFCL were successful. The Progress in Superconductivity is published every six month and serves as a channel for publications on superconductivity and related topics. The author(s) are required to submit THREE copies of the manuscripts along with original figures directly to the Editor.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1993.04a
• /
• pp.119-123
• /
• 1993

Axial load-strain relationships of confined concrete with spiral reinforcement were investigated. The main variables were compressive strength of concrete, spacing of hoop reinforcement, and specimen height of plain concrete. The program included tests of eleven confined specimens, and twelve plain specimens, but for all specimens no longitudinal reinforcement was provided. Load-strain curves of confined and plain concrete specimens are reporeted.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.547-552
• /
• 2001

This research was conducted to investigate the seismic behavior and capacity assessment of circular spiral reinforcement concrete bridge piers used in high strength concrete. The displacement ductility, response modification factor(R), effective stiffness and plastic hinge region etc. was used to assess the seismic behavior and capacity of circular spiral reinforcement concrete bridge piers. The experimental variables of bridge piers test consisted of amount and spacing, different axial load levels. From the quasi-static tests on 9 bridge piers and analysis, it is found that current seismic design code specification of transverse confinement steel requirements and details may be revised.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2143-2145
• /
• 1999

Measurements of wind noise, generated by High-voltage overhead transmission lines placed in a uniform flow are carried out in the Anechoic windtunnel. High-voltage overhead transmission lines generates audible wind noise, which cause a serious environment problem. Accordingly, wind noise has become one of major concerns for design engineers and operations personnel. In the present research, tests were mainly performed with various configuration of transmission line with spiral wires. Remarkable noise reduction was observed for some of the spiral transmission lines, compared with the noise generated without the spiral wire.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.29 no.1
• /
• pp.191-201
• /
• 1999

Purpose: To know whether there would be a difference among spiral tomograms of different slice thicknesses in the measurement of distances which are used for dental implant planning. Materials and Methods: 10 dry mandibules and 40 metal balls were used to take total 120 Scanorailll tomograms with the slice thickness of 2 mm, 4 mm and 8 mm. 3 oral radiologists interpreted each tomogram to measure the distances from the mandibular canal to the alveoalr crest and buccal. lingual and inferior borders of mandible. 3 observers recorded grades of 0, 1 or 2 to evaluate the perceptibility of alveolar crest and the superior border of mandibular canal. ANOVA with repeated measure. Chi-square tests and intrac!ass correlation coefficient(R₂, α) were used For statistical analysis. Results: There was not a statistically significant difference among spiral tomograms with different slice thicknesses in the measurement of the distances and in the perceptibility of alveolar crest and mandibular canal(p>0.05). All of them showed a good relationship in the reliability analysis. The perceptibility of alveolar crest and mandibular canal was almost similar and an excellent relationship was seen on all of them. Conclusions: There would be no significant difference. no matter which spiral tomogram of any slice thickness may be used in dental implant planning. considering the thickness of dental implant fixture.

• Journal of the Korea Concrete Institute
• /
• v.14 no.1
• /
• pp.8-15
• /
• 2002

This paper presents a study carried out for the seismic capacity in reinforced concrete(RC) piers by the confinement effect of transverse reinforcement as such a hooked-tied, welded-tied and spiral reinforcement. In order to assess the seismic capacity with transverse reinforcement, experiment리 and analytical methods were adopted. A RC column survey was conducted based on eight one-fourth scale single circular column specimens designed and tested under slow horizontal cyclic loads. Two cases were analyzed. The confinement effect of concrete by transverse reinforcement is considered not in Case 1 but in Case 2. Also, we studied the propriety of making use of the method in which a carbon fiber rod replace spiral reinforcement in RC piers. In experimental tests, a welded-tied and spiral reinforcement has a good seismic capacity, but a carbon fiber rod presents low ductility in comparison with a hooked-tied reinforcement. In an analytical study, displacement ductility is approximate to the experimental result because of considering the confinement effect of the transverse reinforcement. Even if the confinement effect of the transverse reinforcement is considered, the analytical results for ductility of the specimens with welded-tied and spiral reinforcement show an excessive underestimation of the experimental results.

• Explosives and Blasting
• /
• v.29 no.1
• /
• pp.10-16
• /
• 2011

To make large slopes or rock structures stable, supporting systems, such as anchor bolt, rock bolt and spiral bolt which are developed recently, are commonly used. In this study, in-situ pull-out tests were carried out to compare the characteristics of rock bolt that is most widely used with ones of spiral bolt that is newly developed. Re-pull-out test for the spiral bolt in which loading and unloading cycles are repeated three times showed that the maximum pull-out load is almost constant irrespective of the number of loading cycles, which may be due to no failure between spiral bolt and filler. On the other hand, the maximum pull-out load for the conventional rock bolt decreases with the number of loading cycles due to the partial failure between rock bolt and filler.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.2
• /
• pp.38-46
• /
• 2020

The purpose is to evaluate the structural characteristics of 750 mm diameter injection spiral blades under various operating conditions. A fiber-glass reinforced polypropylene material was employed to the injection blades, and mechanical tests on two kinds of glass-reinforced polypropylene were performed to evaluate the mechanical properties and to select a suitable candidate material. Also, three kinds of spiral blade geometries were studied to observe the influence of fixing rods between blades. For this, structural analyses were conducted to understand the role of fixing rods under a range of rotating speed. In addition, modal analysis was performed to confirm the resonance in the operating speed range. One-way fluid-structure interaction (FSI) analysis was carried out to know its mechanical integrity under dangerous wind speed conditions. Through this work, the structural characteristics of the proposed spiral blade geometries were studied under various operating conditions, and the requirements of mechanical properties of blades were determined.

• Journal of Ocean Engineering and Technology
• /
• v.16 no.5
• /
• pp.49-55
• /
• 2002

The compression anchor is characterized by decrement of progressive failure, simple site work, economy and durability compared with tension anchor. In this paper, compression anchor is analysed through the laboratory element tests. The formula to be estimate the grout strength in fixed part of compression anchor and the effective reinforcement method for several types of soil were suggested. The following conclusions were made from this study : (1) A formula, which is able to calculate the grout strength in the fixed part of the compression anchor, is suggested. (2) The strength increment ratios( $R_{si}$) are 100％, 132％, 147％, 217％ according to the reinforcement method of grout. The reinforcement method is Non, Outside spiral, Inside-Outside spiral, Steel pipe, respectively. (3) The strength increment ratios( $R_{si}$) by reinforcing can be 8.23 times the strength increment effect according to the reinforcement types and ground confining pressure. (4) The steel pipe reinforcement is most effective in decomposed soil while, in the case of hard rock ground, high confining pressure is exerted on the grout, so there is no need to use reinforcements.

• Transactions of Materials Processing
• /
• v.31 no.4
• /
• pp.186-193
• /
• 2022

The application of UHSS sheet is being expanded up to 50% to reduce the weight of automobiles and improve safety. However, due to the high strength and low elongation of the ultra-high tensile strength steel sheet, product defects such as spring back and mold defects such as cracks and chippings also occur. In this study, Pin/Ring on Disc and Spiral wear tests were conducted to evaluate the durability of Ti/Cr-coated molds for forming 1.2GPa grade UHSS sheets. Component analysis and thickness were measured for each coating layer, and hardness and adhesion were investigated to determine mechanical properties. Combining the results of various wear tests, it was found that the TiAlN coating had the best wear and sticking resistance.