• Title/Summary/Keyword: 감쇠능

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The Effect of Alloy Elements on the Damping Capacity and Plasma Ion Nitriding Characteristic of Fe-Cr-Mn-X Alloys [I Damping Capacity] (Fe-Cr-Mn-X계 합금의 감쇠능 및 플라즈마이온질화 특성에 미치는 합금원소의 영향 [I 감쇠능])

  • Son, D.U.;Jeong, S.H.;Kim, J.H.;Lee, J.M.;Kim, I.S.;Kang, C.Y.
    • Journal of Power System Engineering
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    • v.9 no.1
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    • pp.70-75
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    • 2005
  • The damping property of Fe-12Cr-22Mn-X alloys has been investigated to develop high damping and high strength alloy. Particularly, the effect of the phase of austenite, alpha and epsilon martensite, which constitute the structure of the alloys Fe-12Cr-22Mn-X alloys, on the damping capacity at room temperature has been investigated. Various fraction of these phases were formed depending on the alloy element and cold work degree. The damping capacity is strongly affected by ${\varepsilon}$ martensite while the other phase, such as ${\alpha}'$ martensite, actually exhibit little effect on damping capacity. In case of Fe-12Cr-22Mn-3Co alloy, the large volume fraction of ${\varepsilon}$ martensite formed at about 30% cold rolling, and in case of Fe-12Cr-22Mn-1Ti alloy, formed at about 20% cold rolling and showed the highest damping capacity. Damping capacity showed higher value in Fe-12Cr-22Mn-1Ti alloy than one in Fe-12Cr-22Mn-3Co alloy.

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Effect of Cu on the mechanical Properties and damping capacity of austempered ductile cast iron (오스템퍼링 처리한 구상흑연주철의 기계적 성질 및 감쇠능에 미치는 Cu의 영향)

  • Lee, K.H.;Kang, C.Y.
    • Journal of Power System Engineering
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    • v.12 no.3
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    • pp.72-77
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    • 2008
  • This study was investigated to know the effect of Cu addition on austempered ductile cast iron at various temperatures and times. Test results showed that the volume fraction of retained austenite and the carbon contents of retained austenite showed the greatest value at $400^{\circ}C$. Also, in case of specimens having more Cu contents, the volume fraction of retained austenite and the carbon contents of retained austenite showed the lower value. After austempering treatment, tensile strength and Impact value increased, but elongation decreased. With increasing austempering treatment temperature, tensile strength, elongation, and impact value decreased. In case of specimen having more Cu contents, tensile strength showed the higher value, but elongation showed the lower value. Damping capacity was decreased by austempering treatment and was not affected on austempering temperature and time. In case of specimen having more Cu contents, damping capacity showed the higher value.

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High temperature and damping properties of squeeze cast Mg hybrid Metal Matrix Composites. (하이브리드 Mg 복합재료의 진동 감쇠능 및 고온 특성평가)

  • 장재호;김봉룡;최일동;조경목;박익민
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.10a
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    • pp.143-146
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    • 2002
  • Mg alloy is the lightest material of structural materials and is noticed for lightweight automotive parts because of excellent castability, superior ductility and damping capacity than Al alloy. But Mg Alloy is poor corrosion resistance and high temperature creep properties. In this study, Mg Matrix Composites were fabricated by squeeze casting method to improve high temperature creep properties and damping capacity. Hybrid Mg composites reinforced with Alborex, graphite particle, and SiCp was improved creep properties and damping capacity compared with Mg alloy. Compared to the length ($9\mu\textrm{m}, 27\mu\textrm{m}, 45\mu\textrm{m} etc.$), Hybrid Mg composites reinforced with SiCp, one of the most superior of the length and Alborex were more superior than those reinforced with graphite particle and Alborex in mechanical properties, creep characteristics, and damping capacity, etc.

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Effect of Microstructure on the Damping Capacity of 12Cr Martensitic Heat-resisting Steel (12Cr 마르텐사이트계 내열강의 감쇠능에 미치는 미세조직의 영향)

  • Lee, S.M.;Kang, C.Y.
    • Journal of Power System Engineering
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    • v.14 no.2
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    • pp.78-83
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    • 2010
  • This study was carried out to investigate the effect of microstructure on the damping capacity of 12Cr martensite heat-resisting steels, in case of the specimen with martensite phase contained the volume faction of ferrite phases, under 5%. The damping capacity was decreased with the increase of solution treatment temperature and time. While it was increased with the increase of tempering temperature and time. The damping capacity was higher in case of specimen with martensite single phase structure than the specimen with martensite phase contained of ferrite phases.

Effect of Subzero Treatment on the Mechanical Properties and Damping Capacity of Austempered Ductile Cast Ironn (오스템퍼드 구상흑연주철의 기계적 성질 및 감쇠능에 미치는 서브제로처리의 영향)

  • Lee, K.H.;Kwon, M.K.;Kim, C.G.;Kang, C.Y.
    • Journal of Power System Engineering
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    • v.11 no.4
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    • pp.86-91
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    • 2007
  • This study was investigated to know the effect of subzero treatment in austempered ductile cast iron. Retained austenite transformed to martensite by subzero treatment. With decreasing subzero treatment temperature, more volume fraction of retained austenite transformed to martensite and transformed to martensite above 30% by subzero treatment temperature at $-196^{\circ}C$. With decreasing subzero treatment temperature, the value of strength and hardness increased but the value of elongation and impact value decreased. In case of subzero treatment at $-196^{\circ}C$, hardness value increased about 18% and impact value decreased by above 20%. We could find that subzero treated specimens had a little of effect on the tensile properties but had very much effect on the hardness and value of the impact.

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Effect of Reverse Transformation on the Damping Capacity of High Manganease Austenitic Stainless Steel (고 Mn 오스테나이트계 스테인리스강의 감쇠능에 미치는 역변태의 영향)

  • Kang, C.Y.
    • Journal of Power System Engineering
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    • v.16 no.4
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    • pp.60-65
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    • 2012
  • This study was carried out to investigate the effect of reverse transformation on the damping capacity in high manganese austenitic stainless steel. ${\alpha}^{\prime}$-martensite was formed with the specific direction and surface relief by deformation. Over 95% of the austenite phase was transformed to deformation-induced ${\alpha}^{\prime}$-martensite by 70% cold rolling. Reverse transformation became rapid above an annealing temperature of $550^{\circ}C$, but there was no significant transformation above $700^{\circ}C$. In addition, with increasing annealing time at $700^{\circ}C$, reverse transformation was induced rapidly, but the transformation was almost completed at 10 min. Damping capacity was increased up to $700^{\circ}C$, and than unchanged with the increasing annealing temperature. Damping capacity increased steeply with an increasing reverse treatment time up to 10min, whereas there were no significant change with a treatment time of more than 10 min. Damping capacity increased with an increasing the reversed austenite and was strongly affected by reversed austenite.

The Effect of grain size on the damping capacity of Fe-26Mn-2Al alloy (Fe-26Mn-2Al 합금의 진동 감쇠능에 미치는 결정립 크기의 영향)

  • Kang, C.Y.;Eom, J.H.;Kim, H.J.;Sung, J.H.
    • Journal of Power System Engineering
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    • v.11 no.1
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    • pp.115-120
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    • 2007
  • The effect of grain size on the damping capacity of Fe-26Mn-2Al alloy studied in this paper has been investigated after changing the microstructure by cold rolling and changing grain size. Micro structures in Fe-26Mn-2Al at room temperature consist of a large quantity of austenite and a small quantity of ${\varepsilon}\;and\;{\alpha}'$ martensite. And ${\varepsilon}\;and\;{\alpha}'$ martensite was increased by increasing the degree of cold rolling. The content of deformation induced martensite was increased with increasing the degree of cold rolling. Damping capacity was linearly increased with increasing ${\varepsilon}$ martensite content, which suggests that stacking faults and ${\varepsilon}$ martensite variant boundaries are the principle damping sources. With increasing the grain size in Fe-26Mn-2Al alloy, the damping capacity was increased due to increasing the volume fraction of ${\varepsilon}$ martensite by decrement in stability of austenite phase. With decreasing the grain size, the content of deformation induced martensite was decreased and the damping capacity was decreased.

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Development Trend of Damping Mg Alloys (진동 감쇠능 마그네슘 합금의 개발 동향)

  • Jang, Dong-In;Kim, Shae-K.
    • Journal of Korea Foundry Society
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    • v.28 no.5
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    • pp.199-203
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    • 2008
  • 현재 사용되고 있는 진동감쇠능 Mg-Zr 합금인 K1A는 우수한 진동감쇠능을 갖으나 열악한 기계적 특성과 Zr이 고가이면서 고융점 원소로 합금화가 어렵다는 문제점 때문에 진동테이블, 미사일 유도시스템 및 레코딩 장비 등에 소량만 적용되고 있다. Mg-Ni 합금의 경우Ni가 Mg 용탕 내에 고용되지 않아 우수한 진동감쇠능을 갖으나 Fe, Cu등과 함께 Mg의 부식을 가속시키는 원소로 사용이 제한적일 뿐 아니라 Zr과 마찬가지로 Ni도 고융점 원소로 합금화가 어렵다는 것도 문제점으로 작용하고 있다. Mg-Si 합금의 경우 Si이 극소량만 고용되어 우수한 진동감쇠능을 보이며 Ni과 달리 부식에 영향을 받지 않는 원소이지만 Zr, Ni와 마찬가지로 고가이면서 고융점 원소로 합금화가 어렵다는 문제점이 있다. Mg 용탕에 첨가하게 되면 용탕의 표면에 MgO, CaO 피막을 형성하여 발화현상을 억제할 뿐 아리라 첨가량의 증가에 따라 발화온도를 상승시키는 Ca의 경우 Mg 내에 고용되어 진동감쇠능을 감소시킬 뿐 아니라 유동성 저하 및 열간균열을 야기하는 것으로 나타났다. 그러나 CaO의 경우 Mg내에 고용되지 않고, 가격이 저렴하며 Mg 고유 특성의 변화가 적다. 또한 Ca와 같이 Mg 용탕의 발화를 억제하여 보호가스인 $SF_6$를 사용하지 않아도 된다. 이런 다양한 장점을 갖는 CaO를 첨가한 Mg합금이 진동감쇠능을 유지하면서 기계적 특성이 향상된다면 주행 시 안전성 및 정음성이 요구되는 수송기기 분야와 외부충격으로부터 데이터 보호가 필수적인 휴대용 전자정보통신기기 분야에서 적용이 증가할 전망이며 이에 따라 이 분야에 대한 지속적인 연구와 투자가 이루어져야 할 것이다.

A Low Power GaAs MMIC Multi-Function Chip for an X-Band Active Phased Array Radar System (X-대역 능동 위상 배열 레이더시스템용 저전력 GaAs MMIC 다기능 칩)

  • Jeong, Jin-Cheol;Shin, Dong-Hwan;Ju, In-Kwon;Yom, In-Bok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.5
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    • pp.504-514
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    • 2014
  • An MMIC multi-function chip with a low DC power consumption for an X-band active phased array radar system has been designed and fabricated using a 0.5 ${\mu}m$ GaAs p-HEMT commercial process. The multi-function chip provides several functions: 6-bit phase shifting, 6-bit attenuation, transmit/receive switching, and signal amplification. The fabricated multi-function chip with a compact size of $16mm^2(4mm{\times}4mm)$ exhibits a gain of 10 dB and a P1dB of 14 dBm from 7 GHz to 11 GHz with a DC low power consumption of only 0.6 W. The RMS(Root Mean Square) errors for the 64 states of the 6-bit phase shift and attenuation were measured to $3^{\circ}$ and 0.6 dB, respectively over the frequency.

Acoustic-Damping Characteristics of Half-Wave Resonator in a Combustion Chamber of Liquid Rocket Engine (로켓엔진 연소기에서 반파장 공명기의 음향감쇠에 관한 수치적 연구)

  • Sohn Chae-Hoon;Park I-Sun
    • Journal of the Korean Society of Propulsion Engineers
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    • v.9 no.4
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    • pp.9-15
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    • 2005
  • A linear acoustic analysis is performed to explore the characteristics of acoustic damping by a gas-liquid scheme coaxial injector in a liquid rocket engine. The injector can play a role of acoustic resonator. Acoustic-damping characteristics of half-wave resonator are compared with those of quarter-wave resonator. Various effects of the boundary absorption coefficient, injector length and sound speed in combustion chamber and resonator are investigated. As a result, short tuning length of resonator and low sound speed of the medium have a favorable effect on acoustic damping. As the boundary absorption coefficient decreases, the tuning range of the resonator length becomes narrower.