• 한국전기전자재료학회논문지
• /
• 제22권7호
• /
• pp.602-605
• /
• 2009

The heat generation in the high-$T_c$ superconducting (HTS) wire is related with the cost efficiency and safe factor of HTS devices. This paper deals with the thermal quench at the conduction-cooled joint between HTS wire and copper terminals. The 3-D numerical simulation of thermal distributions in part of the copper terminals was implemented and the premature quench at copper block was observed through the test. The results will be helpful to design the conduction-cooled HTS magnets.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.358-359
• /
• 2008

The heat generated in the high-Tc superconducting (HTS) devices is related with the cost efficiency and safe factor of HTS devices. This paper deals with the quench at the conduction-cooled joint between the HTS wire and copper terminals. The 3-D numerical simulation of this phenomenon was implemented and compared with the experimental results. The experiment was implemented with the HTS wire mounted on the copper blocks cooled with a Gifford McMahon (GM) cryocooler.

• 한국초전도ㆍ저온공학회논문지
• /
• 제24권4호
• /
• pp.16-24
• /
• 2022

Applications of REBa₂Cu₃O_7-δ tapes require joints with a simple manufacturing process, low resistance and good mechanical properties. In the present study, we successfully developed a copper diffusion joint between Cu-stabilized REBa₂Cu₃O_7-δ tapes that meets the above requirements without solder simply by applying flux, heat and pressurization. After a 3 min thermocompression process at approximately 150 δ and 336 MPa in air, two tapes were directly connected between Cu stabilizers by copper diffusion, which was proven by microstructure analysis. The specific resistivity of the copper diffusion joint reached 5.8 nΩ·cm² (resistance of 0.4 nΩ for a 306 mm splicing length) at 77 K in the self-field. The axial tensile stress reached 200 N without critical current degradation. The results show promise for the preparation of copper diffusion joints to be used in coils, attached tapes, and wire/cable terminals.

• 한국기계가공학회지
• /
• 제19권10호
• /
• pp.111-116
• /
• 2020

Flexible tactile sensors, which are primarily used as grippers in robots, are mainly used to handle highly elastic or highly flexible objects. That is, flexible grippers are used when an object cannot be sufficiently controlled by applying a specific output force or taking a specific grabbing action. This is because a flexible tactile sensor needs to measure the pressure applied directly to held objects while deforming according to the shape of the object to be handled. CNT-based sensors used to be made from a highly flexible polymer to give flexibility and it is known that the sensors are greatly affected by the contact resistance of the terminal that connects the sensor to an electrical circuit; therefore, this paper clarifies the contact resistance of MWCNTs-based flexible tactile sensors and terminals. The effects of main and plating materials for terminals are investigated and the combinations of main and plating materials that exhibit contact resistance are measured in a typical industrial environment.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제4권3호
• /
• pp.196-203
• /
• 2004

A three-dimensional (3D) IC technology platform is presented for high-performance, low-cost heterogeneous integration of silicon ICs. The platform uses dielectric adhesive bonding of fully-processed wafer-to-wafer aligned ICs, followed by a three-step thinning process and copper damascene patterning to form inter-wafer interconnects. Daisy-chain inter-wafer via test structures and compatibility of the process steps with 130 nm CMOS sal devices and circuits indicate the viability of the process flow. Such 3D integration with through-die vias enables high functionality in intelligent wireless terminals, as vertical integration of processor, large memory, image sensors and RF/microwave transceivers can be achieved with silicon-based ICs (Si CMOS and/or SiGe BiCMOS). Two examples of such capability are highlighted: memory-intensive Si CMOS digital processors with large L2 caches and SiGe BiCMOS pipelined A/D converters. A comparison of wafer-level 3D integration 'lith system-on-a-chip (SoC) and system-in-a-package (SiP) implementations is presented.

• 자동차안전학회지
• /
• 제13권2호
• /
• pp.30-34
• /
• 2021

Electrical failures and reliability problems of electronic components by ionic migration between adjacent device terminals have become an issue in automotive electronics. Especially unlike galvanic corrosion, ionic migration is occurred at high temperature and high humidity under applied electric field condition. Until now, although extensive studies of the ionic migrations dealing with PCBs, electrodes, and solders were reported, there is no study on the effect of insulation polymers and metallic fillers for ionic migration. In this research, therefore, ionic migration induced by the types and contents of polymers and metallic fillers, and variety conditions of temperature, humidity, and applied voltage was studied in detail. Ester and amide types of liquid crystal polymer (LCP) and poly (phthalamide) (PPA) were used as base polymers, respectively and compounded with the metallic fillers of Copper iodide (CuI), Zinc stearate (Zn-st), or Calcium stearate (Ca-st) in various compositions. The compounding polymers were fabricated in IPC-B-24 of SIR test coupon according to ISO 9455-17 with Cu electrodes for ionic migration test. While there is no change in LCP-based samples, ionic migration in PPA compounding sample with a high water absorption property was accelerated in the presence of 0.25 wt% or above of CuI at the environmental conditions of 85℃, 85% RH and 48V. The dendritic short-circuit growth of Cu caused by ionic migration between the electrodes on the surface of compounded polymers was systematically observed and analyzed by using optical microscopy and SEM (EDX).

• 전기전자학회논문지
• /
• 제25권4호
• /
• pp.607-612
• /
• 2021

본 논문에서는 종이와 동 테이프로 만든 CPW로 급전되는 UWB 모노폴 종이 안테나를 제안하고자 한다. 시뮬레이션을 통해 최적화된 안테나 설계 파라미터를 구하고, UWB 주파수 대역인 3.1-10.6 GHz에서 전방향성 방사패턴 및 2.2dBi 이상의 이득을 갖는 안테나를 설계하였다. 일반적인 A4용지와 동 테이프를 이용하여 안테나를 제작하고, 측정 결과 UWB 주파수 대역에서 -10 dB 이하의 반사손실을 만족하였고, 안테나 평면이 길이 방향으로 3mm 굽어진 경우에도 반사손실 특성이 유지됨을 확인하였다. 제안된 안테나는 웨어러블 소자로서 UWB 대역의 서비스를 제공할 수 있고, 종이에 전도성 프린트로 인쇄하여 제작하면 저렴하게 제작이 가능하므로, 물류 분야 및 일회용 단말기 등 다양한 응용 분야에서 UWB 통신용 웨어러블 안테나로 활용이 가능할 것으로 사료된다.

• 센서학회지
• /
• 제32권4호
• /
• pp.219-222
• /
• 2023

Partial discharges (PD) have long been recognized as a major contributing factor to catastrophic failures in high-power equipment. As the demand for high voltage direct current (HVDC) facilities continues to rise, the significance of on-line and real-time monitoring of PD becomes increasingly prominent. In this study, we have designed, fabricated, and characterized a highly sensitive and cost-effective PD sensor comprising a pair of copper electrodes with different arc lengths. The key advantage of our sensor is its non-invasive nature, as it can be installed at any location along the entire power cable without requiring structural modifications. In contrast, conventional PD sensors are typically limited to installation at cable terminals or insulation joint boxes, often necessitating invasive alterations. Our PD sensor demonstrates exceptional accuracy in estimating PD location, with a success rate exceeding 95% in the straight sections of the power cable and surpassing 89% in curved sections. These remarkable characteristics indicate its high potential for realtime and on-line detection of PD.

• Progress in Superconductivity
• /
• 제10권1호
• /
• pp.45-49
• /
• 2008

For the development of superconducting fault current limiters (SFCLs), fault current limiting elements were fabricated out of Bi-2212 bulk tubes and tested. The SFCL elements consisted of tube shaped Bi-2212 bulks and metal shunts for the stabilizers. Firstly, the Bi-2212 bulk tubes were processed based on a design of monofilar coils in order to acquire large resistance and high voltage rating. 300 mm-long Bi-2212 tubes were designed to have the current path of 410 cm in length with 24 turns and 41 mm in diameter. The processed monofilar coil, as designed, had 300 A $I_c$ at 77 K. The fabricated superconducting monofilar coils were affixed to Cu-Ni alloy as that of stabilizers. The Cu-Ni alloys were processed to have the same shape of the superconducting monofilar coils. The Cu-Ni coil had resistivity of 32 ${\mu}{\Omega}$-cm at 77 K and 37 ${\mu}{\Omega}$-cm at 300 K. The metal shunts were attached to the outside of the Bi-2212 monofilar coil by a soldering technique. After the terminals made of copper were attached to both ends of the superconductor-metal shunt composite, the gap between the turns and the surface of the elements was filled with an epoxy and a dense mesh made of FRP in order to enhance the mechanical strength. The completed SFCL elements went through fault tests, and we confirmed that the voltage rating of 143 $V_{rms}$ (E =0.35 $V_{rms}$/cm) could be accomplished.