• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.331-346
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• 2004

A new sensor system is proposed for measuring damage indexes. The damage index is a physical value that is well correlated to a critical damage in a device or a structure. The mechanism proposed here utilizes elastic buckling of a thin wire and does not require any external power supply for memorizing the index. The mechanisms to detect peak strain, peak displacement, peak acceleration and cumulative deformation as examples of damage indexes are presented. Furthermore, passive and active wireless data retrieval mechanisms using electromagnetic induction are proposed. The passive wireless system is achieved by forming a closed LC circuit to oscillate at its natural frequency. The active wireless sensor can transmit the data much further than the passive system at the sacrifice of slightly complicated electric circuit for the sensor. For wireless data retrieval, no wire is needed for the sensor to supply electrical power. For the active system, electrical power is supplied to the sensor by radio waves emitted from the retrieval system. Thus, external power supply is only needed for the retrieval system when the retrieval becomes necessary. Theoretical and experimental studies to show excellent performance of the proposed sensor are presented. Finally, a prototype damage index sensor installed into a 7 storey base-isolated building is explained.

• Progress in Superconductivity
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• 제5권2호
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• pp.149-152
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• 2004

The design and the fabrication of a 1 MVA single-phase HTS transformer are presented in this paper, The rated voltages are 22.9 ㎸ for primary and 6.6 ㎸ for secondary, and the rated currents are 44 A and 152 A respectively. The transformer has HTS double pancake type windings. This type of winding has many advantages such as ease of fabrication and maintenance, good distribution of surge voltage and insulation of windings. Single HTS wire was used for primary winding and four HTS parallel wires were used for secondary winding. These windings are arranged reciprocally with the shell type iron core. An FRP cryostat with room temperature bore was fabricated to isolate the iron core from the coolant. The winding will be cooled down to 65 K with sub-cooled liquid nitrogen using a GM-cryocooler. The sub-cooled liquid nitrogen has advantages of good insulation because of no bubbles as well as increased current capacity of HTS wire.

• 한국전기전자재료학회논문지
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• 제29권6호
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• pp.365-369
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• 2016

In this paper, we fabricated Cu/Mn alloy shunt resistor with low resistance and thermal stability for use of mobile electronic devices. We designed metal alloy composed of copper (Cu) and manganese (Mn) to embody in low resistance and low TCR which are conflict each other. Cu allows high electrical conductivity and Mn serves thermal stability in this Cu/Mn alloy system. We confirmed the elemental composition of the designed metal alloy system by using energy dispersive X-ray (EDX) analysis. We obtained low resistance below $10m{\Omega}$ and low temperature coefficient of resistance (TCR) below $100ppm/^{\circ}C$ from the designed Cu/Mn alloy resistor. And in order to minimize resistance change caused by alternative frequency on circuit, shape design of the metal alloy wire is performed by rolling process. Finally, we conclude that design of the metal alloy system was successfully done by alloying Cu and 3 wt% of Mn, and the Cu/Mn alloy resistor has low resistance and thermal stability.

• 품질경영학회지
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• 제45권4호
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• pp.1003-1020
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• 2017

Purpose: The purpose of this study is to find the optimum working conditions for spot welding of wire Cu alloys to achieve high-level quality. The parts subject to spot welding are brush card assemblies, which are the main module of the electric movement method of the car seat. Methods: In this study, the signal-to-noise ratio(SN ratio) and the loss function [L(y)] are used as Taguchi method for dynamic characteristics. Results: The results of the study are as follows. First, the analysis of variance using SN ratio showed 6 significant factors(p = 0.1% or less) among 7 factors except press force. Second, the optimal design of the dynamic characteristics is the tip exchange cycle: 50,000 ea., the welding time is 110 ms, the pressing force is 11 kgf/cm2, the rise time is 40 ms, and the tip dressing is 3,000 ea., Tip angle is 12o and electric current is 1,800 A. Conclusion: The validity of the spot welding process of the manufacturer's brush card assembly was verified and proved to be consistent with the study results. The results of this study are expected to standardize the welding conditions and guarantee the quality level required by the customers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2226-2227
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• 2008

가공배전선로는 태풍과 같은 자연재해에 상시 노출되어 시설되므로 전기고장 및 설비피해가 발생할 우려가 매우 높다. 그러나 이와 관련한 실질적인 연구들이 부족하여 가공배전선로의 설계원들이 직선선로의 경간 결정시 단순히 저압부하밀도 및 전주강도만을 고려하고 있으며, 인류지선 및 종지선의 규격 선정방법을 잘 이해하지 못함에 따라 규격 선정의 오류가 발생되기도 한다. 따라서 본 고에서는 그 동안의 연구결과를 바탕으로 가공배전선로 설계시 수평선간이격거리를 고려한 경간 결정방법과 장경간 및 표준경간의 인류지선, 장경간개소 종지선 결정방법에 대하여 사례를 통해서 설명하였다. 본 고에서 제시한 방법에 따라 설계검토를 시행한다면 표준경간에서 선간단락고장을 예방할 수 있을 뿐만 아니라, 장경간 및 표준경간의 인류지선 및 종지선의 강도가 재해시에도 충분한 강도를 확보하여 설비피해 및 전기고장을 예방할 수 있을 것으로 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.319-320
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• 2006

At this study, one of the electrical problems, arc characteristics according to loss of contact between a pantograph and a catenary, was analyzed. A characteristic of arc current is disappeared in a short period of time. Nevertheless, it has large current same as a surge, so that it has EMI/EMC problems. In the case of the electrical railway system, there is oscillation and de-wiring. The are current is generated by these problems. The result of this study can be used as a facility design to prevent a surge and needs to prove through actual field data in the main circuit of an electric train for a precise analysis about effect of are.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.121-126
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• 2005

This paper describes the attributes, performance and development status of a high performance capacitive torque sensor intended for use in a electric power steering (EPS) system. The EPS system is composed of torque sensor, ECU, motor, gears and etc. Among the elements, torque sensor in the steering column is one of the core technologies. The new capacitive torque sensor in this paper is developed differently from working principle and mechanical structure compare to extant torque sensors in market and patent. Based on the result of numerical analysis, a experimental equipment is made which is composed of a test jig and a capacitive sensor and validity of numerical analysis and feasibility of the torque sensor are verified.

• International Journal of Railway
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• 제3권2호
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• pp.46-53
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• 2010

Electric railroad systems consist of rolling stock, track, signal and catenary system. In the catenary system, one of the most important factors is the impedance according to the design and characteristic. Before the catenary system is designed, the impedance should be precedently researched. The railroad catenary system is complex system which is composed by five conductors. The five conductors classify up and down feeders, up and down contact wire group, rail group. Therefore, we should compose the catenary system of the equivalent five-conductors model. In this paper, we suggest a geometrical model and a equivalent conductor model by using geometric mean radius of five conductors in the catenary system. Also, we calculate demanded parameter values in the model. By using those, line constants of five conductors are analyzed by applying the equivalent method called as the condensed joint matrix.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1753-1755
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• 2003

MOF insulating cover used in 22.9 kV substation hasn't shown good performance in terms of electrical safety because of its defect by short clearance MOF cover and each input and output wire junction part. The MOF cover is easily moved by outside environment as wind or rain weather because of different size MOF cover and insulating busing, also can be leaded to breakdown by tracking. Therefore, we propose MOF cover which effectively prevents from electrical accidents in this paper. To decrease the electric field concentrated on specific part, we roundly design the shape of MOF cover and clearance between cover and live part was adjusted to be longer than before. The proposed MOF cover is evaluated by using the electric field solution program.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.751-757
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• 2018

In this article, a UV sensor that is an appropriate tool for fire detection has been designed and constructed. The structure of this UV sensor is an air-filled single-wire detector that is able to operate under normal air condition. A reflective CsI photocathode is installed at the end of the sensor chamber to generate photoelectrons in the ion chamber. An electric current is produced by accelerating photoelectrons to the anode in the electric field. The detector is able to measure the intensity of the incident UV rays whenever the current is sufficiently high. Therefore, the sensitivity coefficient of this sensor is found to be $7.67{\times}10^{-6}V/photons/sec$.