• Title, Summary, Keyword: stranded wire

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Analysis on the Characteristics of the Stranded Wire Disconnected by Bending Stress (구부림 피로에 의한 연선의 반단선 특성 해석)

  • Shong, Kil-Mok;Choi, Chung-Seog;Kim, Dong-Woo;Kwak, Hee-Ro
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.464-467
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    • 2003
  • In this paper, we analyzed on the characteristics of the stranded wire disconnected by bending stress. The stranded wire that used in the experiment are PVC insulated flexible cords(VCTFK) of $0.75mm^2,\;1.25mm^2,\;and\;2.0mm^2$. They are used to connect the load in low voltage. The stranded wires disconnected by bending stress were magnified with optical microscope. Using X-ray, the disconnected wire were photographed. we compared mechanical characteristics of the stranded wire between disconnected tendency and allowable current. On the mechanical strength of vinyl captyre ellipse type cords under bending stress, $1.25mm^2$ VCTFK was the strongest of them. When it was bended $826.3{\pm}7\;times$, it appeared the disconnected tendency that element wires of $1.25mm^2$ VCTFK are more about 1.67 times than element wires of $0.75mm^2$ VCTFK. In mechanical strength, $1.25mm^2$ VCTFK is higher about 1.7 times than $0.75mm^2$ VCTFK. Therefore, we found out that mechanical strength will be higher, if element wire is a lot. In comparison with bending stress, $1.25mm^2$ VCTFK is the strongest among samples, and then it is the most useful in wires of movable type.

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Enhancement of Nucleate Pool Boiling of a Wire-Wrapped Tube (와이어붙이관의 핵비등 열전달촉진)

  • 김내현;김정식;남기일
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.5
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    • pp.1235-1244
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    • 1994
  • In this study, experimental results of the nucleate boling of wire-wrapped tubes are provided. Both water and R-113 were boiled. Solid stainless steel wires, stranded copper wires and stranded nylon wires were tested. Solid stainless wire is effective to enhance the boiling of water. The performance is approximately the same(or slightly better at certain conditions) as that of GEWA-T tubes. For the test range of wire diameter 0.6 $mm{\le}d{\le}2.6 mm$, the optimum gap width increases as the wire diameter increases. The maximum heat transfer coefficient was obtained for the 1.0 mm diameter wire, and it is 1.6 times larger than that of the GEWA-T at the heat flux of 20 $kW/m^{2}.$ Solid stainless wire is also effective to enhance the boling of R-113 at low heat fluxes. The performance of the wire-wrapped tube approaches that of GEWA-T. At high heat fluxes, however, the enhancement decreases. The reason may be attributed to the cavity shape and the high wettability of the refrigerants. Stranded copper or nylon wire is effective to enhance the boiling of R-113. The performance is approximately the same(or slightly better) as that of GEWA-T tubes. Maximum heat transfer was obtained for the stranded nylon wire, and it is approximately 1.4 times larger than that for the GEWA-T at the heat flux of 20 $kW/m^{2}.$ The reason may be atrributed to the favorable thermal environment in the restricted regions formed by twisted wires.

A Study on the Characteristics Analysis of Strands Melted by Over Current (과전류에 의해 용단된 소선의 특성해석에 관한 연구)

  • Choi, Chung-Seog;Kim, Hyang-Kon;Kim, Dong-Ook
    • Journal of the Korean Society of Safety
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    • v.19 no.1
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    • pp.60-65
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    • 2004
  • The PVC insulated flexible cords are used mainly as power supply cords of electric appliance. This electric wire is a stranded wire consisted of dozens of strands. In case stranded wires are disconnected by mechanical stress, it weakens electrically. Finally, the over current flows through stranded wires, and electrical fire occurs. In this study, we analyzed the melting properties of strands by over current, such as melting process, melting current and melting time. And we analyzed that quantity of heat for melting, a cross sectional structure, and surface structure by optical microscope and SEM. As analysis results, melting time decreased as melting current increased. And quantity of heat for melting was low, too. From the cross sectional structure of melted wire, when a melting current low and melting time long, it was found that the dendrite structure grew. However, the dendrite structure is hard to grow because growing time is not enough when a melting current high and melting time short.

The Characteristics Analysis of Damaged Pattern by Repeated Stress of VCTFK (VCTFK의 반복피로에 의한 소손 패턴의 특성 해석)

  • Choi Chung-Seog;Shong Kil-Mok;Kim Dong-Woo
    • Journal of the Korean Society of Safety
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    • v.19 no.4
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    • pp.42-47
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    • 2004
  • In this paper, we analyzed on the characteristics of the stranded wire disconnected by repeated stress. The stranded wires that were used in the experiment are PVC insulated flexible cords(VCTFK: Vinyl Insulated Vinyl Cabtyre Cord Flat-type) of $0.75mm^2,\;1.25mm^2,\;and\;2.0mm^2$. They are used to connect the load in low voltage. The stranded wires disconnected by repeated stress were magnified with optical microscope. Using X-ray, the disconnected wire were photo-graphed. we compared mechanical characteristics of the stranded wire between disconnected tendency and allowable current. On the mechanical strength of vinyl cap tire ellipse type cords under bending stress, VCTFK of $1.25mm^2$ was the strongest of them. When it was bent $826.3\pm7$ times, it appeared the disconnected tendency that element wires of VCTFK of $1.25mm^2$ are more about 1.67 times than element wires of VCTFK of $0.75mm^2$. In mechanical strength, VCTFK of $1.25mm^2$ is higher about 1.7 times than VCTFK of $0.75mm^2$. Therefore, we found out that mechanical strength was higher, when the wire had a lot of element wires. In comparison with bending stress, VCTFK of $1.25mm^2$ is the strongest among samples, and it is the most useful in wires of movable type.

The solution for preventing the expansion of cable joint caused by methane($CH_4$) gas to Water proof type of power cable (도체 수밀형 전력케이블의 가교잔사 가스에 의한 직선접속재 부풀음 현상 방지 대책)

  • Kim, Jong-Won;Lee, Ki-Soo;Paek, Heum-Soo;Choi, Bong-Nam;Park, Hee-Cheol
    • Proceedings of the KIEE Conference
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    • pp.2020-2022
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    • 2000
  • The cross-linked polyethylene(herein after XLPE) insulated power cable emit the methane($CH_4$)gas in the course of chemical cross-linking process. The general stranded conductor easily discharge this methane gas through the gap of each stranded wires. But the special stranded conductor that filled with semi-conducting rubber compound to prevent water penetration which is applied to water proof type of cable(22.9kV CN/CV-W), disturb the methane gas emission. The pre-mold type cable joint shall be expanded gradually by emit of gas left in XLPE insulation. For example, sometimes the corona problem outbreak on a new power distribution line, resulted from the gap between the sleeve and semi-conductive layer of cable joint. If above mentioned problem especially happened on the way of operating. We have to shut down the line and try to discharge the methane gas in cable joint. In this point, we would like to explain the mechanism of methane gas & cable joint and our test result briefly. At last, we are pleased to introduce the solution for preventing reoccurrence of this problem.

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Performance and Evaluation of the Messenger Wire stranded by Copper-Clad Steel Conductors for High Speed Electric Railway (동복강선을 적용한 고속선용 조가선의 성능 및 평가 방안)

  • Lee, Chang-Young;Baek, Seung-Koo;Kwon, Sung-Tae;Kim, Jeong-Guk;Chang, Sang-Hoon
    • Proceedings of the KSR Conference
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    • pp.875-880
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    • 2007
  • Due to increasing demands for environment-friendly railway system, bronze wires with cadmium, which is a potential environmental hazard, have been no longer permitted as messenger wire for electric railway system. One of materials being considered as the replacements is copper-clad steel conductor(CCSC), which is currently used as contact wire for high speed operation in the Japanese shinkansen. However, there have been few studies for the application as messenger wire by the CCSC. This study deals with requirements and performances of the messenger wire stranded by the CCSC, especially for high speed electric railway. And the tentative evaluation items and methods to be specified as the Korean railway standard(KRS) are proposed.

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Comparison of three different orthodontic wires for bonded lingual retainer fabrication

  • Baysal, Asli;Uysal, Tancan;Gul, Nisa;Alan, Melike Busra;Ramoglu, Sabri Ilhan
    • The korean journal of orthodontics
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    • v.42 no.1
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    • pp.39-46
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    • 2012
  • Objective: We evaluated the detachment force, amount of deformation, fracture mode, and pull-out force of 3 different wires used for bonded lingual retainer fabrication. Methods: We tested 0.0215-inch five-stranded wire (PentaOne, Masel; group I), $0.016{\times}0.022$-inch dead-soft eight-braided wire (Bond-A-Braid, Reliance; group II), and 0.0195-inch dead-soft coaxial wire (Respond, Ormco; group III). To test detachment force, deformation, and fracture mode, we embedded 94 lower incisor teeth in acrylic blocks in pairs. Retainer wires were bonded to the teeth and vertically directed force was applied to the wire. To test pull-out force, wires were embedded in composite that was placed in a hole at the center of an acrylic block. Tensile force was applied along the long axis of the wire. Results: Detachment force and mode of fracture were not different between groups. Deformation was significantly higher in groups II and III than in group I (p < 0.001). Mean pull-out force was significantly higher for group I compared to groups II and III (p < 0.001). Conclusions: Detachment force and fracture mode were similar for all wires, but greater deformations were seen in dead-soft wires. Wire pull-out force was significantly higher for five-stranded coaxial wire than for the other wires tested. Five-stranded coaxial wires are suggested for use in bonded lingual retainers.

A Study of shear bond strength of bonded retainer according to the bonding method and type of wires (접착방법 및 multistranded wire의 종류에 따른 접착식 보정장치의 전단접착강도에 관한 연구)

  • Lee, Hyoung-Cheol;Son, Woo-Sung
    • The korean journal of orthodontics
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    • v.32 no.2
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    • pp.143-153
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    • 2002
  • The bonded orthodontic retainer constructed from composite and multistrand orthodontic wire provides an esthetic and efficient system for maintained retention. This study was designed to measure shear bond strength of bonded retainers and to suggest a optimal combination of a multistrand wire and bonding method used when bonded retainer was fabricated. 160 sound maxillary and mandibular premolars were used for 80 test samples. After Uniformizing bonding area, length of wire, and thickness of composite, multistrand wire was bonded to fabricated a bonded retainer by direct or indirect bonding method. Shear bond strength and extension length of each sample were measured by a universal testing machine. The results of this study were as follows : 1. In vitro shear bond testing found 6-stranded, 0.0155 inch wires to have the largest shear bond strength and 3-stranded, 0.0195 inch wires to have the least shear bond strength. But, These difference was not statistically significant(p<0.05). 2. In vitro extension testing found 3-stranded, 0.0155 inch wires to have the largest extension length and 3-stranded, 0.0195 inch wires to have the least extension length(p<0.05). The larger diameter wire was used, the larger extension length was shown. But, the strand of wire is not related to the extension length of wire. 3. In comparison with direct bonding method, larger shear bond strength and extension length was shown in indirect bonding method(p<0.05).

Fatigue Life Properties of Messenger Wire with Service Environments (가설환경에 따른 조가선의 피로수명 특성)

  • 김용기;장세기;조성일
    • Journal of the Korean Society for Railway
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    • v.6 no.1
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    • pp.21-28
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    • 2003
  • Environment-dependent fatigue life of Cu-Cd alloy wires used as messenger wires was investigated. Tensile test results showed the decrease of tensile strength and elongation of messenger wires by 3.7% and 16.8%, respectively, in used specimens when compared to new ones. Messenger wires used at industrial region for 26 yeras showed 35∼50% decrease in fatigue life, which is partly due to the in stress concentrations by formation of corrosion products at the surface. Single wires showed better fatigue properties than stranded wires, especially at low cycle regions with higher stresses. Stranded wires showed shorter fatigue lives than single wires because of friction between wires by surface contact. Service life of messenger wires was dependent upon the environments which they were exposed to. SO$_2$ and humidity deteriorated the fatigue properties by environmental degradation.

Prediction on Fatigue Life of Messenger Wire with Service Environments (사용환경에 따른 조가선의 피로수명 예측)

  • Chang Seky;Kim Yong-Ki
    • Journal of the Korean Society for Railway
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    • v.8 no.6
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    • pp.525-532
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    • 2005
  • Fatigue life of catenary wires in various environments is reduced when stress is concentrated on some points, which are often found in corroded areas by surrounding pollutants. Therefore, the fatigue test were performed in order to investigate the effect of the surface corrosion on the destructive behavior in service environment and accelerated corrosion environment as well as th examine the corrosive property and mechanism of the catenary wires. In the fatigue test of the messenger stranded wire, the corrosion degraded materials showed 35~50% of fatigue life at a same stress amplitude compared to original material. Because the catenary wires have variable load by the interaction of periodic contacts with pantographs the maximum stresses of trolley wire and messenger wire calculated by simulation at the messenger wire during operation was estimated thought the corrosion behavior interpretation of variable stress and fatigue test.