• Proceedings of the KSR Conference
• /
• 1998.05a
• /
• pp.533-539
• /
• 1998

Described in this paper are the dynamic model and the dynamic performance of catenary-pantograph system for TGV-K(maximum operating speed of 300km/hr). Dynamic simulations showed that the system satisfies the performance criteria such as contact loss ratio, contact force and lift-off of the contact wire. It is also shown by the simulations that the dynamic behavior and contact performance of the system at the operating speed of 350km/hr are found unacceptable. Design parameters of the catenary-pantograph system should be optimized for the speed-up of the TGV-K.

• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.445-452
• /
• 1998

The dynamic performance design of catenary-pantograph system which collects current for the next generation Korean high speed train(KHST) was considered. Used was the same dynamic model of the catenary-pantograph system as that of TGV-K which will be introduced for Kyung-bu corridor. Using the model , sensitivity analysis fer design variables were made to improve dynamic performance of KHST system. The results of sensitivity analysis and performance improvement are as follows: (1) It was found that aerodynamic force, tension of contact wire, mass of contact strip, mass of supporting contact strip, mass of clamp, mass of steady arm, and stiffness of plunger were the design variables most influencing the dynamic performance of the system. (2) Pantograph with reductions of 20% aerodynamic force, 34% weight of supporting contact strip, 20% spring constant of plunger, and 34% equivalent mass of steady arm was very possible system for the KHST which will be running at maximum operating speed 350 km/h.

• Proceedings of the KSR Conference
• /
• 1999.11a
• /
• pp.209-217
• /
• 1999

A catenary system should be designed to be an uniform elasticity over a span in order to maintain the lowest possible loss of contact between a pantograph and a contact wire. A elasticity disuniformity of a catenary can be regarded as a important design factor used for predicting the current collection performance for a catenary. There are a couple of formulas to calculate elasticity disuniformity of a catenary according to the literature survey, The effectiveness of these formulas is reviewed by performing catenary elasticity and loss of contact analysis for 5 different configurations of catenary systems using a beam element based FEM program, KRRI developed program, and the loss of contact by GASENDO, RTRI developed program, respective]y. The results reveals that these formulas are not suitable to predict the current collection performance for a catenary. Therefore, a new formula based on the standard deviation of the elasticity over a span is proposed in this study. The analysis results show that the new formula for an elasticity disuniformity of a catenary is very effective in predicting the current collection performance for a catenary.

• International Journal of Safety
• /
• v.4 no.2
• /
• pp.18-23
• /
• 2005

There are many electrical connections in the electric apparatus and most fires due to a fault contact result from a failure or misuse of electric apparatus and installation. The fault contact happens between electrical connections by the loose and the mechanical vibration. In this paper, we have investigated thermal and electrical properties of screwed electric contacts due to the mechanical vibration. The exciter was connected to a signal generator and power amplifier that provided the vibration frequency and amplitude. The vibration, temperature and voltage data were sent to a data acquisition system (DAQ). In the case that fault contact took place, the arc happened between the screwed electric contact and electric wire, heat due to the arc was transmitted to the adjacent insulators, for which the oxide could be generated more. In addition, a spark was generated and the insulator began to melt. Thus, the possibility of electrical fire became the highest in this case. Finally, when the fault contact takes place due to vibration, the hazard of an electric accident is very high.

• Journal of the Korean institute of surface engineering
• /
• v.25 no.6
• /
• pp.309-317
• /
• 1992

Evaluation of electroplated gold has been carried out to obtain the data base for electrical, mechanical and environmental properties for telecommunication component applications. Gold plating was performed to a various thickness of $0.1\mu\textrm{m}$ to 1.$25\mu\textrm{m}$ after Ni plating of $3\mu\textrm{m}$ on C52100 bronze. Electrical properties were evaluated by measuring contact resistance using 4-wire method under static contact and dynamic contact during wear. Reciprocating wear test was performed to study the wear behavior as well as failure of gold contacts. Environmental characteristics were evaluated by using salt spray testing and SO2 test. Hardness of soft gold film was measured to be 53KHN under 5g load. Friction coefficient was initially obtained to be 0.15 and 0.25 under 100g and 200g loads respectively, and then raised up to 0.8 with increasing reciprocating wear cycles. Static contact resistance was 2 to 3m$\Omega$ regardless of gold film thickness while drastic changes of contact resistance were occured upon stripping of the gold film during wear. The lifetime of contact wear showing stable contact resistance increased up to 6 times for $1\mu\textrm{m}$ thickness compared to that of$ 0.1\mu\textrm{m}$ thickness under 100g load. All gold plating appeared to be stable under salt atmosphere while only the gold plating over 1$\mu\textrm{m}$ was stable under SO2 atmosphere.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1374-1378
• /
• 2005

Appropriate upward force is crucial for the pantograph on high speed train to collect current from the catenery system without separation. However, at high speed, large aerodynamic lifting force is generated by the contact plate and the arms of pantograph, which may cause wear of the contact wire. In this study, to confirm the interface performance of the pantograph on Korea High Speed Train, a method to measure the contact force of the pantograph was proposed and the related measurement system was developed. The forces acting on the pantograph were clarified and a procedure to calculate the aerodynamic lifting force was proposed. A special device was invented and applied to measure the lifting force. Measured contact forces were displayed by the developed system and evaluated according to the criteria. Countermeasures were also taken to reduce the contact force based on the results.

• Journal of the Korean Society of Safety
• /
• v.32 no.2
• /
• pp.27-33
• /
• 2017

This study is intended to identify issues on the basis of investigating the actual state of laboratory environment and outlet circuit, and derive end states by expressing sequences from the initiating event of disaster to accident in leakage current, poor contact and overload through ETA(event tree analysis). To this end, this study investigated the actual state of electric equipment of laboratory at universities in all parts of country. And it is shown that most of them are failure in electric work and user negligence in the investigation of actual state. It is found that there is earth fault and defect in wire diameter in the failure of electric work and the problem of partial disconnection due to wire bundling and poor contact in user negligence. Outlet-related component, failure rate and initiating events are composed of a total of 41 initiating events, i.e., 30 internal initiating events and 11 external initiating events. And end states are composed of a total of 15 parts, i.e., 3 electric power parts and 12 safety parts. Earthing class 3 is the most important safety device against leakage current (initiating event). And in case of poor contact, it is necessary for manager to check thoroughly because there is no safety device. In case of overload/overcurrent, when high-capacity equipment is connected, a molded case circuit breaker, safety device, worked. However, in most cases, it is verified that this doesn't work. This study can be utilized as electric equipment safety guide for laboratory safety manager and managers.

• The korean journal of orthodontics
• /
• v.24 no.3 s.46
• /
• pp.735-758
• /
• 1994

This study was designed to investigate the displacements and reaction forces of teeth caused by the application of the rectangular shape-memory arch wires with curve of Spee. Computer-aided three dimensional finite element method was adopted. This finite element model consists of brick element for teeth, beam element for the wire, and contact element for the periodontal ligament. And the application of the MEAW(Multiloop Edgewise Arch Wire) was also studied so that the results of the two methods can be compared each other. Total number of the nodes and elements were found to be 5925 and 4031, repectively. In addition, several types of elastics and corresponding displacements and reaction forces were examined. The findings of this study were as follows: 1. When the rectangular shape-memory arch wire with curve of Sun was used alone, the intrusion and labioversion was noticeable on the upper incisors, while the upper molars showed less intrusion. With MEAW, the intrusion and labioversion of the upper incisors were slightly larger than those when the shape-memory arch wire was used, but on the upper molars the opposite result was obtained with respect to the intrusion. 2. The shape-memory arch wire with the vertical elastics caused the larger downward displacement on the upper canine than that when the MEAW was used with the vertical elastics. However, the downward displacement of the upper incisors was larger in MEAW. The uprighting and buccoversion of the molars were observed in both cases. 3. The use of the Class II or III elastics showed the extrusion and changes in torque of the corresponding teeth. The downward displacement of the upper canine was increased when the Class II and vertical elastics were applied simultaneously, but it was decreased when both of the Class III and vertical elastics were used.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2010.04a
• /
• pp.63-67
• /
• 2010

원문이미지 참조

• Fire Science and Engineering
• /
• v.18 no.4
• /
• pp.72-77
• /
• 2004

In this paper, we studied on the short-circuit process, surface structure, and component variation of vinyl cords. In the results of high speed imaging system (HSIS) analysis, as soon as wire covering was damaged by heat, the conductor of wire came in contact with the other conduct of wire, and the short-circuit occurred. Stereomicroscope and SEM analysis indicated that the source part of wire showed V-type form. The molten beads of load part were bigger than those of source part. In the results of EDX analysis, Cu and O were detected in the source part, whereas covering material (Cl, Ca), Cu and O were detected in the load part. The results will help us to find out the cause of electrical fire.