• Journal of Power System Engineering
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• v.13 no.2
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• pp.36-41
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• 2009

An experimental investigation was conducted to examine the fluid flow resistance in the rectangular channel with two inclined wire screen baffles. Two different types of wire screens; dutch weave and plain weave, were used as baffle devices in this experiment. Three kinds of baffles with different mesh specifications were made up of dutch type and four different kinds of baffles were made up of plain weave type. The stainless steel wire screen baffles were mounted on the bottom wall with varied angle inclination. Reynolds numbers were varied from 23,000 to 57,000. Results show that the mesh number of baffles plays an important role on friction factor behaviour. It is found that the baffle with the most number of meshes (type SA) has the highest fluid flow resistance.

• Journal of Welding and Joining
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• v.31 no.4
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• pp.42-46
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• 2013

The contact tip for flux cored arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. A damaged contact tip causes a productivity reduction and a welding quality problem. In this study, the welding experiments for the wear resistance of contact tip regarding flux cored wire types were performed. With two fold type and a seamless type flux cored wires, the wear rates of contact tips were compared. In addition, the wear rate was checked according to the contact tip position.

• The korean journal of orthodontics
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• v.31 no.4 s.87
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• pp.467-477
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• 2001

This investigation was designed to determine the effects of wire size, bracket width and the number of bracket on bracket-wire dynamic frictional resistance during simulating arch wire-guided tooth movement in vitro. For simulation of an arch wire-guided tooth movement, we simulated tooth, periodontal ligament and cancellous bone. Maxillary premolar and 1st molar were simulated as real sized resin teeth, the simulated resin teeth which its root was coated by polyether impression material which its elastic modulus is similar to periodontal ligament were embedded in steel housing with inlay wax which its elastic modulus is similar to cancellous bone. Stainless steel wires in four wire size (0.016, 0.018, $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$ inch) were examined with respect to three (stainless steel) bracket widths (2.4, 3.0, 4.3mm) and the number of medium bracket(one, two, three) included in the experimental assembly under dry condition. The wires were ligated into the brackets with elastomeric module. The results were as follows : 1. In all the brackets, frictional resistance increased with increase in wire size. But, statistically similar levels of frictional resistance were observed between 0.018 inch and $0.016\;{\times}\;0.022$ inch wires in narrow bracket and also between 0.016 inch and 0.018 inch wire in wide backet. 2. The frictional forces produced by 0.016 inch wire were statistically similar levels in all the brackets. In 0.018 inch round wire, wide bracket was associated with lower amounts of friction than both narrow and medium brackets. In $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$ inch rectangular wire, wide bracket produced target friction than both narrow and medium brackets. In all the wirer, narrow and medium bracket demonstrated no statistical difference in levels of frictional resistance. 3. Frictional resistance increased with increase In number of medium bracket. 0.016 inch round wire demonstrated the greatest increment in frictional resistance, followed by $0.019\;{\times}\;0.025,\;0.016\;{\times}\;0.022$ inch rectangular wire which were similar level in increment of frictional resistance, 0.018 inch wire demonstrated the least increment. The increments of frictional resistance were not constantly direct proportion to number of bracket.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.272-278
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• 1999

Tungsten Carbide(WC) Roll is widely used in finishing stands of wire rod mill. This report is about the manufacturing method of WC roll with excellent wear resistance. To enhance wear resistance, WC content has been increased to the maximum extent while binder content such as Co, Ni, Cr has been minimized. Part of WC is replaced with TiC having more wear resistant than WC. WTiC powder has been used to prevent weight unbalance resulting from the difference of specific weight when adding TiC. The roll manufactured by this method, is having more wear resistance than the existing rolls when applying to the final stand of the finishing mill. This report shows that WC is the critical factor of wear resistance in WC rolls and an approprite amount of TiC effects wear resistance and when adding TiC, using WTiC powder is better.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.147-155
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• 2008

The dental orthodontic wire provides a good combination of strength, corrosion resistance and moderate cost. The purpose of this study was to investigate the effects of TiN and ZrN coating on corrosion resistance and physical property of orthodontic wire using various instruments. Wires(round type and rectangular type) were used, respectively, for experiment. Ion plating was carried out for wire using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen was observed with field emission scanning electron microscopy(FE-SEM), energy dispersive X-ray spectroscopy(EDS), atomic force microscopy(AFM), vickers hardness tester, and electrochemical tester. The surface of TiN and ZrN coated wire was more smooth than that of other kinds of non-coated wire. TiN and ZrN coated surface showed higher hardness than that of non-coated surface. The corrosion potential of the TiN coated wire was comparatively high. The current density of TiN coated wire was smaller than that of non-coated wire in 0.9% NaCl solution. Pit nucleated at scratch of wire. The pitting corrosion resistance $|E_{pit}-E_{rep}|$ increased in the order of ZrN coated(300 mV), TiN coated(120 mV) and non-coated wire(0 mV).

• Corrosion Science and Technology
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• v.9 no.5
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• pp.223-232
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• 2010

NiTi alloy has been used for orthodontic wire due to good mechanical properties, such as elastic strength, friction resistance, and high corrosion resistance. Recently, these wire were coated by polymer and ceramic materials for aesthetics. The purpose of this study was to investigate electrochemical characteristics of tooth colored NiTi wire using various instruments. Wires (round type and rectangular type) were used, respectively, for experiment. Polymer coating was carried out for wire. Specimen was investigated with optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDS). The corrosion properties of the specimens were examined using potentiodynamic tests (potential range of -1500 ~ 2000 mV) and electrochemical impedance spectroscopy (frequency range of 100 kHz ~ 10 mHz) in a 0.9 % NaCl solution by potentiostat. From the results of polarization behavior, the passive region of non-coated NiTi wire showed largely, whereas, the passive region of curved NiTi wire showed shortly in anodic polarization curve. In the case of coated NiTi wire, pitting and crevice corrosion occurred severely at interface between non-coated and coated region. From the results of EIS, polarization resistance(Rp) value of non-coated round and rectangular NiTi wire at curved part showed $5.10{\times}10^5{\Omega}cm^2$ and $4.43{\times}10^5{\Omega}cm^2$. lower than that of coated NiTi wire. $R_p$ of coated round and rectangular NiTi wire at curved part showed $1.31{\times}10^6{\Omega}cm^2$ and $1.19{\times}10^6{\Omega}cm^2$.

• Korean Journal of Materials Research
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• v.12 no.2
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• pp.103-111
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• 2002

The thermally insulated underground pipelines have been used for district heating system. The sensor wire embedded in the insulation was used for monitoring the insulating resistance between the sensor wire and the pipe. The resistance measurement system detects corrosion of steel pipe under insulation. The corrosion and stress corrosion cracking(SCC) characteristics of sensor wire in synthetic ground water were investigated using the electrochemical methods and constant load SCC tests. The polarization tests were used to study the electrochemical behavior of sensor wire. The sensor wire was passivated at temperatures ranging from 25 to $95^{\circ}C$. However, the applied sensing current larger than passive current resulted in breakdown of passive film. The constant load SCC tests were performed to investigate the effects of applied current and load on the fracture behavior. Stress-corrosion cracks initiated at pits that were produced by sensing current. The growth of the pit involves a tunnelling mechanism, which leads to ductile fracture.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.506-511
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• 2001

Weld overlay has been developed to improve the property of material surface which is used in the severe environment. Weld overlay is the process which uses an arc heat and welds different composition of alloy on the substrate for the improvements of heat resistance and wear resistance. Weld overlay has a lot of advantages which are high hardness, good processing efficiency, easy controlling of layer thickness, good quality and low cost. In this study, weld overlay was performed by MAG welding on the base metal(SS400) with filler metal which contain composite powders(Cr+C+Mn+Mo+NbC) and solid wire(JIS-YGW11). Characterization of hardness and wear resistance were analyzed by EDS, EPMA, XRD and observations of microstructure were performed to investigate characteristics of overlays. The experimental results of overlaid specimens manufactured with Cr+C+Mn+Mo+NbC powders were obtained as fellows. ${\alpha}-phase$, M(Fe, Cr)3C and NbC of overlays were increased with decreasing the wire feed rates and increasing powder feed rates. Also the hardness of overlays were increased and the specific wear were decreased.

• Smart Structures and Systems
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• v.3 no.2
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• pp.189-200
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• 2007

As a functional material, shape memory alloy (SMA) has attracted much attention and research effort to explore its unique properties and its applications in the past few decades. Some of its properties, in particular the electrical resistance (ER) based self-sensing property of SMA, have not been fully studied. Electrical resistance of an SMA wire varies during its phase transformation. This variation is an inherent property of the SMA wire, although it is highly nonlinear with hysteresis. The relationship between the displacement and the electrical resistance of an SMA wire is deterministic and repeatable to some degree, therefore enabling the self-sensing ability of the SMA. The potential of this self-sensing ability has not received sufficient exploration so far, and even the previous studies in literature lack generality. This paper concerns the utilization of the self-sensing property of a spring-biased Nickel-Titanium (Nitinol) SMA actuator for two applications: ER feedback position control of an SMA actuator without a position sensor, and estimation of the opening of a SMA actuated valve. The use of the self-sensing property eliminates the need for a position sensor, therefore reducing the cost and size of an SMA actuator assembly. Two experimental apparatuses are fabricated to facilitate the two proposed applications, respectively. Based on open-loop testing results, the curve fitting technique is used to represent the nonlinear relationships between the displacement and the electrical resistance of the two SMA wire actuators. Using the mathematical models of the two SMA actuators, respectively, a proportional plus derivative controller is designed for control of the SMA wire actuator using only electrical resistance feedback. Consequently, the opening of the SMA actuated valve can be estimated without using an extra sensor.

• Journal of Korean Society for Quality Management
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• v.42 no.3
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• pp.301-310
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• 2014

Purpose: The purpose of this study is to improve a mechanism of expendable bathythermograph measurement by balancing wire resistances between plus wire part and minus wire part and by removing effects of sea water resistance between XBT(Expendable Bathythermograph) and temperature recorder. Methods: The problems are exactly found out through the analysis of XBT and temperature recorder circuit. A process of XBT manufacturing that balances wire resistances between plus wire part and minus wire part is added. Results: The results of this study are as follows; the complicated test process such as temperature accuracy test with a cistern is substituted with a simple process of XBT manufacturing such as balancing wire resistances between plus wire part and minus wire part. Then, the temperature accuracy tolerance of XBT is improved up to ${\pm}0.1^{\circ}C$. Conclusion: Consequently, balancing wire resistances and removing effects of sea water resistance improve temperature accuracy of XBT and reduce expensive and harassing process of XBT manufacturing.