• 제목/요약/키워드: primary silicon

검색결과 106건 처리시간 0.023초

분동교환기를 이용한 고체밀도기준물의 질량측정 (Mass measuremeant of soilid density standard using weight exchanger)

  • 이용재;장경호;오재윤;정상덕
    • 한국정밀공학회:학술대회논문집
    • /
    • 한국정밀공학회 2003년도 춘계학술대회 논문집
    • /
    • pp.1659-1662
    • /
    • 2003
  • The mass measurement of solid density standards using weight exchanger is described. KRISS(Korea Research Institute od Standards and Science) has several solid density standards. Their mass have been measured manually only using a mass comparator(Mettler, 1kg - 0.01mg). However, the uncertaity of the manual mass measurement is up to 300 microgarm much more than 32 microgram of advanced NMIS(National Metrology Institutes) for 1 kg silicon sphere which is primary density standards due to an eccentric error and buoyancy correction error. The new system with a weight exchanger is designed and built to improve the measurement accuracy. It comprises a weight exchager, a mass comparator, air density instruments, and application program for automatic measurement. It is evaluated by measuring several elements in an air tight chamber to verify the performance of it.

  • PDF

고규소(高珪素)-AI합금(合金)의 고온강도(高溫强度)에 관(關)한 연구(硏究) (A Study on the Strength of High-Silicon Aluminium Alloys at Elevated Temperatures)

  • 남태운
    • 한국주조공학회지
    • /
    • 제3권4호
    • /
    • pp.256-261
    • /
    • 1983
  • In this study, the variations of tensile strength and yield strength of Al-20% Si alloy were studied. Copper, magnesium and nickel as alloying elements added from 1% to 3% respectively. The temperature range was from room temperature to $350^{\circ}C$. The refinement of primary silicon crystal was treated with phosphorous addition. The results obtained are as follows: 1. Tensile strnegth and yield strength showed more increased strength in refining treated alloy than that of in nonrefining alloy at elevated temperature. 2. Tensile strength and yield strength were increased with the contents of copper. Tensile strength showed the maximum at $150^{\circ}C$, but yield strength was decreased with increasing temperature. 3. The effect of magnesium addition on tensile strength and yield strength showed the maximum at 1% addition and $150^{\circ}C$. 4. Tensile strength and yield strength showed a slight increase with the content changes of nickel and they were decreased with increasing temperature.

  • PDF

A SIMPLE METHOD TO CALCULATE THE DISPLACEMENT DAMAGE CROSS SECTION OF SILICON CARBIDE

  • Chang, Jonghwa;Cho, Jin-Young;Gil, Choong-Sup;Lee, Won-Jae
    • Nuclear Engineering and Technology
    • /
    • 제46권4호
    • /
    • pp.475-480
    • /
    • 2014
  • We developed a simple method to prepare the displacement damage cross section of SiC using NJOY and SRIM/TRIM. The number of displacements per atom (DPA) dependent on primary knock-on atom (PKA) energy was computed using SRIM/TRIM and it is directly used by NJOY/HEATR to compute the neutron energy dependent DPA cross sections which are required to estimate the accumulated DPA of nuclear material. SiC DPA cross section is published as a table in DeCART 47 energy group structure. Proposed methodology can be easily extended to other materials.

Decannulation Difficulty의 치험례 (A Case of Decannulation Difficulty)

  • 안회영;차창일;박경유
    • 대한기관식도과학회:학술대회논문집
    • /
    • 대한기관식도과학회 1983년도 제17차 학술대회연제순서 및 초록
    • /
    • pp.14.1-14
    • /
    • 1983
  • 기관발거 곤란증은 주로 외상으로 인한 경우가 많으나 의인적인 기관손상, 즉 high tracheostomy, 부적절한 cannula사용, 2 차감염, 육아조직생성 및 기관전벽의 광범위한 절제 등과, 기타 정신적인요소등이 그 원인으로 알려져 있으며 치료로는 steroid사용, stent삽입, 기관공확장술 및 협착부위를 절제한 후 단단봉합하는 등의 방법이 알려져 있다. 최근 저자들은 2세된 남아에서 기관지 이물제거를 위해 기관절개술을 시행한 후 발생한 기관발거 곤란증 환자에서 Silicon T-tube를 사용하여 치유한 예를 문헌고찰과 함께 보고한다.

  • PDF

The Effect of Copper on Feeding Characteristics in Al-Si Alloys

  • Young-Chan Kim;Jae-Ik Cho
    • 한국주조공학회지
    • /
    • 제43권6호
    • /
    • pp.294-301
    • /
    • 2023
  • The effects of Cu on feeding and macro-porosity characteristics were investigated in hypo- (A356 and 319) and hypereutectic (391) aluminum-silicon alloys. T-section and Tatur tests showed that the feeding and macro-porosity characteristics were significantly different between the hypo- and hypereutectic alloys. The hole and the pipe in the T-section and the Tatur casting in hypereutectic alloy showed a rough and irregular shape due to the faceted growth of the primary silicon, while the results of the hypoeutectic alloys exhibited a rather smooth surface. However, the addition of Cu did not strongly affect the macro-feeding behavior. It is known that copper segregates and interferes the feeding process in the last stage of solidification, possibly leading to form more amount of micro shrinkage porosity by the addition of Cu. The macro porosity formation mechanism and feeding properties were discussed upon T-section and Tatur tests together with an alloying addition.

Characteristics of the magnetic flux-offset type FCL by switching component

  • Jung, Byung-Ik;Choi, Hyo-Sang
    • 한국초전도ㆍ저온공학회논문지
    • /
    • 제18권2호
    • /
    • pp.18-20
    • /
    • 2016
  • The study of superconducting fault current limiter (SFCL) is continuously being studied as a countermeasure for reducing fault-current in the power system. When the fault occurred in the power system, the fault-current was limited by the generated impedance of SFCLs. The operational characteristics of the flux-offset type SFCL according to turn ratios between the primary and the secondary winding of a reactor were compared in this study. We connected the secondary core to a superconductor and a SCR switch in series in the suggested structure. The fault current in the primary and the secondary winding of the reactor and the voltage of the superconductor on the secondary were measured and compared. The results showed that the fault current in the load line was the lowest and the voltage applied at both ends of the superconductor was also low when the secondary winding of the reactor had lower turn ratio than the primary. It was confirmed based on these results that the turn ratio of the secondary winding of the reactor must be designed to be lower than that of the primary winding to reduce the burden of the superconductor and to lower the fault current. Also, the suggested structure could increase the duration of the limited current by limiting the continuous current after the first half cycle from the fault with the fault current limiter.

멤브레인 구조 제작은 위한 단결정 실리콘의 이방성 습식 식각 (Anisotropic Wet Etching of Single Crystal Silicon for Formation of Membrane Structure)

  • 조남인;강창민
    • 반도체디스플레이기술학회지
    • /
    • 제2권4호
    • /
    • pp.37-40
    • /
    • 2003
  • 반도체 장비의 기능성과 신뢰성을 높이기 위하여 부품의 제조기술은 점차 마이크로 머신 기술을 요구하고 있다. 마이크로머신 기술 중 hot junction이 위치하는 멤브레인 구조는 각종 센서와 히터의 미세부품에서 가장 이용도가 큰 구조이다. 실험에서는 마이크로머신의 기본 구조인 멤브레인 형태를 만들기 위해 KOH 용액과 TMAH 용액으로 단결정 실리콘을 이방성 습식식각 하였다. 실험결과, 식각액의 온도와 농도, 마스크 패턴과 웨이퍼의 결정성의 일치 등을 고려해야 하며, 식각 속도는 KOH 농도 및 온도에 따라 크게 변함을 알 수 있었다. KOH 용액은 30 wt% 80~$90^{\circ}C$ 온도 범위에서 가장 좋은 특성을 나타냈다. 한편, TMAH용액이 실리콘을 식각하는 용액으로 관심을 끄는 것은 단결정에서 상대적으로 $SiO_2$ 박막을 마스크로 사용할 수 있을 뿐 아니라 $SiO_2$ 박막을 마스크로 사용할 수 있을 뿐 아니라 다른 식각액보다 찌꺼기가 적다는 장점 때문이다. 그러나, 다른 용액에 비해 가격이 고가이며 식각 속도가 낮다는 것이 실용적인 측면에서 큰 단점이다. 실험결과를 종합적으로 고려할 때 KOH 용액 농도 30wt%와 온도 $90^{\circ}C$가 마이크로머신 기술에 의한 멤브레인 구조 제작에서 적합한 공정조건이라고 할 수 있다.

  • PDF

Calibration transfer between miniature NIR spectrometers used in the assessment of intact peach and melon soluble solids content

  • Greensill, Colin.V.;Walsh, Kerry.B.
    • 한국근적외분광분석학회:학술대회논문집
    • /
    • 한국근적외분광분석학회 2001년도 NIR-2001
    • /
    • pp.1127-1127
    • /
    • 2001
  • The transfer of predictive models using various chemometric techniques has been reported for FTNIR and scanning-grating based NIR instruments with respect relatively dry samples (<10% water). Some of the currently used transfer techniques include slope and bias correction (SBC), direct standardization (DS), piecewise direct standardization (PDS), orthogonal signal correction (OSC), finite impulse transform (FIR) and wavelet transform (WT) and application of neural networks. In a previous study (Greensill et at., 2001) on calibration transfer for wet samples (intact melons) across silicon diode array instrumentation, we reported on the performance of various techniques (SBC, DS, PDS, double window PDS (DWPDS), OSC, FIR, WT, a simple photometric response correction and wavelength interpolative method and a model updating method) in terms of RMSEP and Fearns criterion for comparison of RMSEP. In the current study, we compare these melon transfer results to a similar study employing pairs of spectrometers for non-invasive prediction of soluble solid content of peaches.

  • PDF

표면크랙 예측을 위한 결정립 제어 레오로지 소재 표면의 나노 변형특성에 관한 연구 (A Study on the Nano-Deformation Characteristics of Grain-Size Controlled Rheology Material Surfaces for Surface Crack Prediction)

  • 윤성원;김현일;강충길
    • 한국정밀공학회:학술대회논문집
    • /
    • 한국정밀공학회 2004년도 추계학술대회 논문집
    • /
    • pp.355-358
    • /
    • 2004
  • In this study, the deformation characteristics of grain-size controlled rheology materials surfaces were investigated as a part of the research on the surface crack prediction in semi-solid formed automobile components. The microstructure of rheology Al-Si alloys consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary region of semi-solid aluminum alloys (356 alloy and 319 alloy) were investigated through the nanoindentation/scratch experiments and the AFM observation.

  • PDF