• 제목/요약/키워드: surface comparison

검색결과 3,779건 처리시간 0.032초

Sn-Cu 무연 도금용액 및 피막의 신뢰성평가 (A Reliability Test for ph-free SnCu Plating Solution and It's Deposit)

  • 이홍기;허진영
    • 한국표면공학회지
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    • 제38권6호
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    • pp.216-226
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    • 2005
  • Pb-Free Technology was born with environmental problems of electronic component, Being connected by big and small project of every country. Also, in each country environment is connected and various standards of IEC, ISO, MIL, JIS, KS, JEDEC, EIAJ etc. All products can divide at solder part and finishing part These can tested each and synthetically divide. This research is reliability evaluation for three kind of ph-free SnCu solder plating solution and it's deposit. First, executed analysis about Pure Sn, SnCu solutions and plating surface by way similar to other plating solution analysis. Next, executed reliability about test method and equipment for reliable analyzer system construction. Next, data comparison and estimation, main estimation test method and item's choice. In this paper the systematic surface analysis and reliability for plating solutions and it's deposit in metal surface finishing processes could be shown.

Simulation of Turbulent Flow and Surface Wave Fields around Series 60 $C_B$=0.6 Ship Model

  • Kim, Hyoung-Tae;Kim, Jung-Joong
    • Journal of Ship and Ocean Technology
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    • 제5권1호
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    • pp.38-54
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    • 2001
  • A finite difference method for calculating turbulent flow and surface wave fields around a ship model is evaluated through the comparison with the experimental data of a Series 60 $C_B$=0.6 ship model. The method solves the Reynolds-averaged Navior-Stokes Equations using the non-staggered grid system, the four-stage Runge-Kutta scheme for the temporal integration of governing equations and the Bladwin-Lomax model for the turbulence closure. The free surface waves are captured by solving the equation of the kinematic free-surface condition using the Lax-Wendroff scheme and free-surface conforming grids are generated at each time step so that one of the grid surfaces coincides always with the free surface. The computational results show an overall close agreement with the experimental data and verify that the present method can simulate well the turbulent boundary layers and wakes as well as the free-surface waves.

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Surface and Interfacial Energetic Analysis of Amphiphilic Copolymers

  • Kim, Min-Kyun;Yuk, Soon-Hong;Jhon, Mu-Shik
    • Bulletin of the Korean Chemical Society
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    • 제8권3호
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    • pp.158-161
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    • 1987
  • A Series of hydrophilic-hydrophobic copolymeric surfaces of 2-hydroxyethyl methacrylate (HEMA) and various alkyl methacrylate (RMA) have been prepared by in-situ solution copolymerization using a redox radical initiator. Contact angles of various probing fluids on the polymeric surfaces were determined in air (hydrophobic environment) and under water (hydrophilic environment). From contact angle data, the dispersive interaction contribution (${\gamma}^d_s$) and the polar contribution (${\gamma}^p_s$) to the total surface free energy (${\gamma}^d_s$) and interfacial energetic quantities (e.g., water-polymer, liquid-polymer interface, etc.) were estimated by surface and interface physicochemical theory. From the comparison of surface energetic components between hydrophobic and hydrophilic media, it is found that surface and interface energetic components of polymeric surface as a representative low-energy surface are highly dependent on environmental fluids. Also, from the correlation between interfacial energetic results and surface energetic criterion of biocompatibility, we found that HEMA/BMA, HEMA/HMA copolymer systems are in the region of biocompatibility.

Comparison of changes in retentive force of three stud attachments for implant overdentures

  • Kim, Su-Min;Choi, Jae-Won;Jeon, Young-Chan;Jeong, Chang-Mo;Yun, Mi-Jung;Lee, So-Hyoun;Huh, Jung-Bo
    • The Journal of Advanced Prosthodontics
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    • 제7권4호
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    • pp.303-311
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    • 2015
  • PURPOSE. The aim of this study was to compare the changes in retentive force of stud attachments for implant overdentures by in vitro 2-year-wear simulation. MATERIALS AND METHODS. Three commercially available attachment systems were investigated: Kerator blue, O-ring red, and EZ lock. Two implant fixtures were embedded in parallel in each custom base mounting. Five pairs of each attachment system were tested. A universal testing machine was used to measure the retentive force during 2500 insertion and removal cycles. Surface changes on the components were evaluated by scanning electron microscopy (SEM). A Kruskal-Wallis test, followed by Pairwise comparison, was used to compare the retentive force between the groups, and to determine groups that were significantly different (${\alpha}$<.05). RESULTS. A comparison of the initial retentive force revealed the highest value for Kerator, followed by the O-ring and EZ lock attachments. However, no significant difference was detected between Kerator and O-ring (P>.05). After 2500 insertion and removal cycles, the highest retention loss was recorded for O-ring, and no significant difference between Kerator and EZ lock (P>.05). Also, Kerator showed the highest retentive force, followed by EZ lock and O-ring, after 2500 cycles (P<.05). Based on SEM analysis, the polymeric components in O-ring and Kerator were observed to exhibit surface wear and deformation. CONCLUSION. After 2500 insertion and removal cycles, all attachments exhibited significant loss in retention. Mechanism of retention loss can only be partially explained by surface changes.

두개의 마이크로폰을 이용한 흡음재의 음향특성 조사 (A Study on the Acoustical Characteristics of the Absorbent Materials Using Two Microphones)

  • 정성수;황철호
    • 소음진동
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    • 제6권2호
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    • pp.225-231
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    • 1996
  • A free field method using two microphones is used for measuring surface impedance and absorption coefficient of the absorbent materials. It is shown that this method can be performed in a large non-anechoic room. Precise values of the surface impedance can be obtained by changing the spaces between the two microphones. Comparison between experimental values of the surface impedance of the glass wool and the mineral wool and Miki's empirical model shows agreement.

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Compact Model of Tunnel Field-Effect-Transistors

  • Najam, Faraz;Yu, Yun Seop
    • 한국정보통신학회:학술대회논문집
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    • 한국정보통신학회 2016년도 춘계학술대회
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    • pp.160-162
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    • 2016
  • A compact model of tunnel field effect transistor (TFET) has been developed. The model includes a surface potentia calculation module and a band-to-band-tunneling current module. Model comparison with TCAD shows that the mode calculates TFET surface potential and drain current accurately.

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기상청 현업 모델 RDAPS와 QuikSCAT 해상풍 자료의 비교 (Comparison of KMA Operational Model RDAPS with QuikSCAT Sea Surface Wind Data)

  • 유승협;조재갑;서장원
    • 한국해안해양공학회지
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    • 제19권5호
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    • pp.467-475
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    • 2007
  • 기상청 현업 모델 RDAPS 모델 자료와 QuikSCAT 관측결과 중 2005, 2006년 해상풍 자료를 비교하였다. 해상풍의 하계와 동계의 평균 공간 분포의 분석결과 한반도 주변의 계절적인 해상풍의 뚜렷한 특성을 잘 나타낸다. 모델과 관측의 해상풍 통계 분석 비교에서도 계절적인 차이를 잘 나타낸다. 한반도 주변의 하계 BIAS 값은 -0.5m/s이하의 분포를 보이고, 동계에는 -1 m/s이하의 분포를 보인다. 상관계수의 경우 하계에는 0.7, 동계에는 0.8 이상으로 분포한다. 공간적으로 평균된 상관계수의 경우 2005년, 2006년 모두 하계보다 동계에 더욱 상관관계가 높은 것으로 나타났다. 이것은 하계의 약한 풍속보다 동계의 강한 해상풍을 RDAPS에서 더 잘 재현하고 있는 것으로 판단된다.

자성유체 자유표면의 형상 제어에 관한 연구 (A Study on the Deformation control of Free Surface of Magnetic Fluid)

  • 안창호;김대영;지병걸;이은준;박명관
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 춘계학술대회 논문집
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    • pp.297-300
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    • 2002
  • In this study, the deformation of the free surface motion of a magnetic fluid for the change in electromagnetic force is discussed and carried out theoretically and experimentally on the basis of Rosensweig Ferrohydrodynamic Bernoulli Equation. While applied magnetic fields are induced by 4$\times$4 electromagnet located under the magnetic fluid, the surface of the magnetic fluid is formed the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body farce. In case, magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. thus, the device of a magnetic fluid proposed the surface actuator. The device of surface deformation as well comparison between numerical simulation and experiments as will be presented.

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온라인 방식의 지능형 NURBS 곡면 보간기 (Intelligent NURBS Surface Interpolator with Online Tool-Path Planning)

  • 구태훈;지성철
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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    • pp.471-474
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    • 2004
  • In this paper, a NURBS surface interpolator is proposed which can deal with shapes defined from CAD/CAM programs on a surface basis and can improve contour accuracy. The proposed interpolator is based on newly defined G-codes and includes online tool-path planning suitable for NURBS surface machining. The real-time interpolation algorithm, considering an effective machining method for each machining process and minimum machining time, is executed in an online manner. The proposed interpolator is implemented on a PC-based 3-axis CNC milling system and evaluated through actual machining in terms of machining time and regulation of feedrate and cutting force in comparison with the existing method.

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표면분석용 인증표준물질의 개발 I : 표면조성분석용 합금박막 표준물질 (Development of certified reference material (CRM)s for surface analysis I : alloy thin film for surface compositional analysis)

  • 김경중;박용섭;문대원
    • 한국진공학회지
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    • 제8권3B호
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    • pp.276-282
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    • 1999
  • For the quantitative surface analysis of multicomponent materials, algorithms for the compensation of the matrix effect and surface compositional change by ion beam sputtering must be established and reference materials having certified compositions are necessary. These certified reference material (CRM)s are needed for the improvement of instrument performance, inter-laboratory comparison and quantitative surface analysis. Surface analysis group of KRISS developed alloy thin film CRMs by and ion beam sputter deposition system and in-situ surface analysis system to control the composition of alloy thin films The real compositions of the CRMs were certified by inductively coupled plasma-atomic emission spectroscopy (ICP-AES).

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