• 한국정밀공학회지
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• 제32권9호
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• pp.799-805
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• 2015

The further development of information, communication and digital media technologies requires the use of advanced, miniaturized semiconductor chips that operate at a high frequency. Die bonding and wire bonding methods for semiconductor packaging have been replaced by direct attachment to the substrate after forming a bump on the chip. However, the height of the bump or ball is an important factor for defects during assembly. This paper proposes an algorithm to measure the height of the bumps or balls in semiconductor packaging with greater accuracy. The performance of the proposed algorithm is experimentally validated. Non-contact 3D measurements of a shiny round ball is quite difficult, and it is not easy to obtain accurate data. This paper thus proposes an optical method and technique to improve the measurement accuracy.

• Smart Structures and Systems
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• 제10권3호
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• pp.299-312
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• 2012

The authors' research efforts recently led to the development of a customized wireless control unit which receives the real-time feedbacks from the sensors, and elaborates the consequent control signal to drive the actuator(s). The controller is wireless in performing the data transmission task, i.e., it receives the signals from the sensors without the need of installing any analogue cable connection between them, but it is powered by wire. The actuator also needs to be powered by wire. In this framework, the design of a power management unit is of interest only for the wireless sensor stations, and it should be adaptable to different kind of sensor requirements in terms of voltage and power consumption. In the present paper, the power management efficiency is optimized by taking into consideration three different kinds of accelerometers, a load cell, and a non-contact laser displacement sensor. The required voltages are assumed to be provided by a power harvesting solution where the energy is stored into a capacitor.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.152-157
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• 2012

In this paper, smoothing plane connector have been proposed as the vehicle connector for the wireless access in vehicular environments (5.925GHz) communication. This smoothing plane connector is designed by considering the properties of critical parameter like smoothing distance of start to end point of contact area. The design simulation and results can be used to determine the most suitable smoothing plane wire dimensions for vehicle communication connector. The optimized WAVE connector inserted the smoothing plane wire has insertion loss less than-0.17dB at 5.925GHz. It provides 20% of insertion loss with good performance. Therefore, the simulated results can be effectively used for optimum design of high frequency connector for vehicle communication.

• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.159-164
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• 2012

In this paper, it tried to develop the core sensor for detection of micro magnetic field in electric wires. The sensor is non contact type and is consisted of ferrite core for low price. To investigate their properties for variations of current, it changed the number of winding and the length of sample core, it examined, to check the live wire situation in built-in wires, electrical characteristics due to difference between electric wires and core sensor. As the results, it verified live wire situation at the number of winding(5,000) and within length of 6[cm]. Also, it obtained magnetic field magnitude decreased inverse proportion ratio to a square about difference between electric wires and core sensor.

• 한국철도학회논문집
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• 제6권1호
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.503-508
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• 2002

In this study, the relation between the mtation which are usually caused by the creep of the contact wire, the bar geometry and the forces(wire tensions) for the triangle-shaped distribution bar and straight-shaped one in dependent tensioning device system is reviewed. According to the result a rotation of distribution bar in triangle-shaped one modifies the distribution of the tensions between the three wires hooked in a distribution bar. On the contrary, a rotation on the straight-shaped one leads to no tension distribution change. Therefore, to use the straight-shaped distribution bar instead of triangle-shaped one is recommended. In addition, the design contents of the distribution bar which will be used in electrification of Gyeongbu line are described in this paper.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.806-809
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• 2000

A key technology for achieving commercial Nb$_3$Sn superconducting wires may be driven from fabrication Process of big-scale billets. Sub-element billet with diameter of 200 mm was designed and fabricated. This billet was hot-extruded and drawn. Cu stabilizer tube, Nb barrier tube and 19 sub-elements inserted Sn core were composed for strand. There was no breakage in the strand that was constituted with annealed sub-element. It was need that billet had to treat HIP because of remove of voids and goad contact between Cu and Nb filaments. Ta wound sheet was better than Ta tube thor barrier in the strand. Ic of the Nb$_3$Sn wire at 127, 4.2K was over than 120 A.

• 한국철도학회논문집
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• 제7권1호
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• pp.14-19
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• 2004

The effect of surface damage on fatigue properties of catenary wires were investigated to estimate their service lift. As surface defects of the wires caused by surface corrosion increase, surface roughness gets worse, and as roughness increases, it is easy for moisture coming from rain and dew to be condensed around uneven parts of the surface. The condensed moisture causes a locally severe corrosion which leads to damage of the wires. Corrosion of catenaty wires can make their actual lifetime shorter than that originally designed. The amount of decrease was more prominent as environmental conditions became more corrosive. They are also vibrated with some amplitude everytime pantographs touch contact line. The frequent cyclic load on the wire may result in a fatigue fracture. Surface damage by corrosion can make formation of crack initiation at fatigue. In the present study, the fatigue life of the used wire was measured 35 to 50% compared with that of new one in average.

• 한국구조물진단유지관리공학회 논문집
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• 제23권1호
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• pp.130-137
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• 2019

PC구조형식은 사전 제작된 PC 부재를 현장에서 거치한 후 추가 긴장력 도입 및 연결부 시공의 과정을 거쳐서 구조물을 완성시키는 형식이다. 하지만 현장타설부와 PC부 사이 부착면에서 균열발생 및 수밀성 감소에 따른 누수문제가 발생할 수 있다. 이러한 균열 및 누수문제는 철근의 부식을 초래할 수 있으며, 이는 구조물의 장기사용 내구성을 급격히 감소시키는 주요 원인이 될 수 있다. 본 연구에서는 기존 PC 구조물 접합부 경계면에서의 부착력 부족에 대한 문제를 해결하기 위해서, 형상기억합금을 활용한 표면처리 부재를 제안하고, 형상기억합금 와이어를 이용한 연결부의 성능을 평가하고자 하였다. 이를 위해서 본 연구는 해당 기술 실현을 위한 사전연구로서 와이어의 개수와 절곡유무, 그리고 형상기억효과 발현 유무에 따른 연결재의 인발력을 평가하고자 하였다. 연구결과를 통해서 SMA 연결재의 인발저항성능을 결정짓는 연결부의 형상효과와 형상기억발현효과, 그리고 부착효과에 대해서 평가할 수 있었다. 또한 이에 대한 설계변수별 예측식을 제안하였고, 예측값과 실험값 간의 유효성을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.595-601
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• 2004

The pantograph for Korean High Speed Train was developed and had been evaluating by through 'G7-R&D project' for home grown high speed train technology. In this paper, from the point of view in mechanical aspect, comparison study on the current collection characteristics between the KHST pantograph and contact wire in catenary system on the High-Speed Line and Ho-Nam/Kyoung-Bu conventional lines is conducted. A measuring system for the performance and mechanical characteristics of the KHST pantograph is used for this study, which was developed and installed on the Proto-type Korean High Speed Train, and physical characteristics were measured while the KHST runs on the High-Speed Line and conventional lines. Through this study, remarkable variations of characteristics which can affect to a current collection quality of high-speed train are found and analyzed from measured mean contact forces in both tracks.