• Title, Summary, Keyword: Ultra-low temperature

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Effect of Coiling Temperature on the Annealed Texture in Cu/Nb Added Ultra Low Carbon Steels

  • Jiang, Yinghua;Park, Young-Koo;Lee, Oh-Yeon
    • Korean Journal of Materials Research
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    • v.18 no.2
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    • pp.65-68
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    • 2008
  • The present work was performed to investigate the effect of coiling temperature on the annealed texture in Cu/Nb-added ultra-low-carbon steels. The ultra-low-carbon steels were coiled at 650 and $720^{\circ}C$, respectively. The result showed that the Cu-added ultra-low-carbon steel at a low coiling temperature produced a desirable annealed texture related to good formability. On the other hand, Nb-added ultra-low-carbon steel at a high coiling temperature also produced a desirable texture. This is attributed to the effect of Nb, which retards recrystallization during the coiling process.

Effects of Alloy Additions and Annealing Parameters on Microstructure in Cold-Rolled Ultra Low Carbon Steels (극저탄소 냉연강판에서 합금원소 및 어닐링조건이 미세조직에 미치는 영향)

  • Jeong, Woo Chang
    • Journal of the Korean Society for Heat Treatment
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    • v.17 no.2
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    • pp.78-86
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    • 2004
  • Effects of the annealing parameters on the formation of ferrites transformed at low temperatures were studied in cold-rolled ultra low carbon steels with niobium and/or chromium. Niobium and chromium were found to be effective in the formation of the low temperature transformation ferrites. The low temperature transformation ferrites more easily formed when both higher annealing temperature and longer annealing time, allowing substitutional alloying elements to distribute between phases, are in combination with faster cooling rate. It was found from EBSD study that the additions of niobium or chromium resulted in the increase in the numbers of high angle grain boundaries and the decrease in those of the low angle grain boundaries in the microstructures. Both granular bainitic ferrite and bainitic ferrite were characterized by the not clearly etched grain boundaries in light microscopy because of the low angle grain boundaries.

A Study of Dyeability at Low Temperature on the Ultra-microfiber (해도사의 저온염색성에 대한 고찰)

  • 장지은;강민주;최재홍
    • Textile Coloration and Finishing
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    • v.16 no.3
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    • pp.8-13
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    • 2004
  • This research aimed at scrutinizing the comparative dyeability of some disperse dyes at low temperature on ultra-microfiber polyester, islands in the sea type (0.05 denier), which has claimed utmost fastness and improved uptake of dyeing. Comparisons of dyeability, such as rate of dyeing and color depth, on ultra-microfiber polyester were evaluated by H.T. exhaust dyeing method and followed by the test of rubbing fastness. To achieve high wet fastness, some commercial disperse dyes, Terasil WW and Megacron dyes, which have been recently launched for excellent wash fastness, have been examined compared with conventional disperse dyes, C.I Disperse Red 167 and C.I Disperse Orange 30.

Development of Ultra-high Capacitance MLCC through Low Temperature Sintering (저온소결을 통한 초고용량 MLCC 개발)

  • Sohn, Sung-Bum;Kim, Hyo-Sub;Song, Soon-Mo;Kim, Young-Tae;Hur, Kang-Heon
    • Journal of the Korean Ceramic Society
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    • v.46 no.2
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    • pp.146-154
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    • 2009
  • It is necessary to minimize the thickness of Ni inner electrode layer and to improve the coverage of inner electrode, for the purpose of developing the ultra high-capacity multi layered ceramic capacitor (MLCC). Thus, low temperature sintering of dielectric $BaTiO_3$ ceramic should be precedently investigated. In this work, the relationship between dielectric properties of MLCC and batch condition such as mixing and milling methods was investigated in the $BaTiO_3$(BT)-Dy-Mg-Ba system with borosilicate glass as a sintering agent. In addition, several chip properties of MLCC manufactured by low temperature sintering were compared with conventionally manufactured MLCC. It was found that low temperature sintered MLCC showed better DC-bias property and lower aging rate. It was also confirmed that the thickness of Ni inner electrode layer became thinner and the coverage of inner electrode was improved through low temperature sintering.

Whole-body Management System using Ultra-Low Temperature Cyclical Cooling Method Combined with IT Technology (IT 기술을 접목한 초저온 순환 냉각 방식의 전신 관리 시스템)

  • Kim, Joo-Ho;Lee, Joo-Hyun;Lee, Seung-Ho
    • Journal of IKEEE
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    • v.24 no.2
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    • pp.673-676
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    • 2020
  • In this paper, we propose a whole-body management system using ultra-low temperature cyclical cooling method combined with IT technology. The proposed system has the following characteristics. First, it minimizes maintenance costs by circulating nitrogen gas cooled by ultra-low temperature inside the controller. Secondly, based on the information measured by the temperature sensor and oxygen concentration sensor, nitrogen gas is supplied to provide safe ultra-low temperature whole-body management. Thirdly, after entering the user's height, it provides convenient, ultra-low temperature whole-body care that can be controlled using an automatic lift. Fourth, it provides an easy-to-access, easy-to-manage GUI and a manager-only web program for whole-body management system operation. The results tested by the authorized testing agency to assess the performance of the proposed system were measured in the range of ±5%, the world's highest temperature sensor accuracy, and a range of -110℃ to -150℃ greater than the world's highest whole-body management temperature range(-110℃ ~ -140℃). In addition, humidity was measured at less than 40%, the world's highest, and oxygen concentration was more than 18%, the world's highest. Therefore, the effectiveness of the methods proposed in this paper was demonstrated because they produced the same results as the world's highest levels.

An Ultra Low-Power and High-Speed Down-Conversion Level Shifter Using Low Temperature Poly-Si TFTs for Mobile Applications

  • Ahn, Soon-Sung;Choi, Jung-Hwan;Choi, Byong-Deok;Kwon, Oh-Kyong
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1279-1282
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    • 2006
  • An ultra low-power down-conversion level shifter using low temperature poly-crystalline silicon thin film transistors is proposed for mobile applications. The simulation result shows that the power consumption of the proposed circuits is only 17% and the propagation delay is 48% of those of the conventional cross-coupled level shifter without additional area. And the measured power consumption is only 21% of that of the crosscoupled level shifter.

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High-temperature superconducting filter and filter subsystem for mobile telecommunication

  • Sakakibara, Nobuyoshi
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.35-39
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    • 2000
  • Large-area high-temperature superconducting (HTS) films, filter design and damage-free processing technique have been developed to fabricate low insertion loss and sharp skirt filters. Further, long life cryocooler, low temperature low noise amplifier (LNA) and cryocable have been developed to assemble HTS filter subsystem for IS-95 and IMT-2000 mobile telecommunication. The surface resistance of the films was about 0.2 milli-ohm at 70 K, 12 GHz. An 11-pole HTS filter for IS-95 telecommunication system and a 16-pole HTS filter for IMT-2000 telecommunication system were designed and fabricated using 60 {\times}$ 50 mm$^2$ and one half of 3-inch diameter YBCO films on a 0.5-mm-thick MgO substrate, respectively. We have assembled the filter and low temperature LNA in a dewar with the cryocooler. Ultra low-noise (noise figure: 0.5 dB at 70 K) and ultra sharp-skirt (40 dB/1.5 MHz) performance was presented by the IS-95 filter subsystem and the IMT-2000 filter subsystem, respectively.

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Densification of Mo Nanopowders by Ultra High Pressure Compaction (초고압 성형을 통한 Mo 나노 분말의 치밀화)

  • Ahn, Chi Hyeong;Choi, Won June;Park, Chun Woong;Lee, Seung Yeong;Kim, Young Do
    • Korean Journal of Materials Research
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    • v.28 no.3
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    • pp.166-173
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    • 2018
  • Molybdenum (Mo) is one of the representative refractory metals for its high melting point, superior thermal conductivity, low density and low thermal expansion coefficient. However, due to its high melting point, it is necessary for Mo products to be fabricated at a high sintering temperature of over $1800-2000^{\circ}C$. Because this process is expensive and inefficient, studies to improve sintering property of Mo have been researched actively. In this study, we fabricated Mo nanopowders to lower the sintering temperature of Mo and tried to consolidate the Mo nanopowders through ultra high pressure compaction. We first fabricated Mo nanopowders by a mechano-chemical process to increase the specific surface area of the Mo powders. This process includes a high-energy ball milling step and a reduction step in a hydrogen atmosphere. We compacted the Mo nanopowders with ultra high pressure by magnetic pulsed compaction (MPC) before pressureless sintering. Through this process, we were able to improve the green density of the Mo compacts by more than 20 % and fabricate a high density Mo sintered body with more than a 95 % sintered density at relatively low temperature.