• 제목/요약/키워드: Surface quality

검색결과 5,180건 처리시간 0.027초

연삭가공에 있어 비가공 시간 단축에 관한 연구(II) (Reducing the Non Grinding Time in Grinding Operations(2nd report) -Decision of Dressing Chance and Depth by the Direct Measurement of Grinding Wheel Surface-)

  • 김선호;안중환
    • 한국정밀공학회지
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    • 제14권8호
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    • pp.101-107
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    • 1997
  • In general, grinding is one of the final machining processes which determines the surface quality of machined products. Since the ground surface is affected by the states of grains and voids on the grinding wheel surface, the wheel should be dressed before the machined surface deteriorates over a quality limit This paper describes a systematic approach to decide a proper dressing chance and an optimal dressing depth for the working grinding wheel. An eddy current sensor and a laser displacement sensor are used to measure the loading on the working wheel surface and the topography of the dressed wheel surface respec- tively. The dressing chance can be properly decided through the relational locus between the amount of handing and the machined surface roughness. An optimal dressing depth to guarantee the less wheel loss and the higher wheel surface quality is decided through the analysis of the variance of topography for the dressed wheel surface, which decreases at three different rates according to the accumulated dressing depth.

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반응표면(反應表面) 분석(分析)을 위한 실험계획(實驗計劃)과 그 응용(鷹用) 통계적(統計的) 모형(模型)의 최적화수법론(最適化手法論)을 중심으로 (Application of Analysis of Response Surface and Experimental Designs ; Optimization Methodology of Statistical Model)

  • 이명주
    • 품질경영학회지
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    • 제7권2호
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    • pp.22-28
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    • 1979
  • The problem considered in this paper is to select the vital factor effect to the product quality through the experimental design and analysis of response surface, so as to control the quality improvement of industrial product. In this time, even through the mathematical model is unknown it could be applicable to control the quality of industrial products and to determine optimum operating condition for many technical fields, particulary, for industrial manufacturing process. When a set of data is available from an experimental design, it is often of interest 1:0 fit polynominal repression model in independent variables (eg, time, temperature, pressure, etc) the optimize the response variable (eg. yield, strength etc). This paper proposes a method known to obtain the optimum operating condition, and how to find the condition by using table of orthogonal array experiments, and optimization methodology of statistical model. A criterion can be applied determining to optimum operating conditions in manufacturing industry and improving the fit of response surface which may be used for prediction of responses and quality control of industrial products.

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Characterization of Surface Quality in Orthogonal Cutting of Glass Fiber Reinforced Plastics

  • Choi Gi Heung
    • International Journal of Safety
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    • 제3권1호
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    • pp.1-5
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    • 2004
  • This study discusses frequency analysis based on autoregressive (AR) time series model, and the characterization of surface quality in orthogonal cutting of a fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using AR time series model. The experimental correlations between the fiber pull-out and AR model coefficients are then established.

콘크리트 바닥 시험체의 크기가 SL재의 균열에 미치는 영향 - SL재의 하자 발생에 영향을 미치는 콘크리트 표층부의 품질 평가방법(I) - (Evaluation on Crack in Self-leveling Material and Investigation about Influence of Specimen Size - Evaluation Method about Surface Layer Quality of Concrete Floor Groundwork Corresponding to Defect in Self-leveling Material (Part I) -)

  • 김두호;최수경
    • 한국건축시공학회지
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    • 제7권2호통권24호
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    • pp.99-106
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    • 2007
  • The purpose of this study presents in Relations between cracks in self-leveling material and quality of floor groundwork surface are experimentally examined. As the first stage, the experiment to observe cracks in self-leveling material constructed on floor groundwork made from various kinds of concrete was carried. As a result, following basic findings were obtained. First, observation of cracks should be continued until an increase in width of cracks stop, without constructing any finishing material. Second, degree of cracks may be indicated quantitatively by the product of length and width. Finally, Cracks and separation is not be influenced by specimen size. Based on these findings, the method of predicting cracks by evaluating surface layer quality of floor groundwork will be established.

RTM공법을 이용한 승용차용 복합재료 휠의 표면정도 향상 및 개발 (Improvement of Surface Quality and Development of Composite Wheel for Passenger Cars Manufactured by RTM)

  • 김포진;이대길
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.54-57
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    • 2003
  • Since passenger cars require five wheels including a spare, the weight reduction of wheels without sacrificing performance is important. Recently, the structured components of cars made of steel are replaced by composites. plastics and other nonmetallic materials such as aluminum and magnesium for weight reduction. From these new tried materials are most promising due to their high specific stiffness and specific strength. The composites manufactured by resin transfer molding (RTM) process has not only low cost for the manufacturing but also reduces the lead time and development because the molds for RTM is easy to manufacture. In this work, composite wheels for passenger cars were designed and manufactured by RTM process. Since surface quality of wheels is important for passenger cars, the optimal stacking sequence for composite wheels was selected considering surface quality and mechanical properties. Also, the manufacturing method for the composite mold was depicted.

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순환골재 품질개선을 위한 수분흡수제어형 표면처리방법 (Water Absorbtion Controlling Type Surface Treatment Method for Quality Enhancement of Recycled Aggregate)

  • 최희복
    • 한국건축시공학회지
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    • 제15권6호
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    • pp.561-567
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    • 2015
  • 본 연구는 순환골재의 품질을 개선시키기 위해 pH 10.2의 알칼리성을 띄고 있는 입경 5nm~60nm 정도의 40% 콜로이달 실리카 수용액을 사용하고, 4가지 표면처리방법을 적용하여 순환골재의 품질 향상 시험을 하였다. 순환골재의 품질시험은 비중, 흡수율, 기공률, 계면특성, 그리고 압축 및 인장시험을 하였다. 100kpa의 일정 압력하에서 콜로이달 실리카 수용액이 표면에 도포되고 $60^{\circ}C$에서 건조됨으로써 콜로이달 실리카 용액이 순환골재의 시멘트 모르타르의 표면을 일정한 두께로 효과적으로 코팅되었다. 4가지 표면처리 방법 중 Method C에 의한 표면처리방법이 순환골재의 품질을 효과적으로 개선시켰으며, 그로인해 순환골재콘크리트의 압축강도 및 인장강도 향상에 영향을 미친 것으로 판단된다.

Analysis of Nutrient Dynamics and Development of Model for Estimating Nutrient Loading from Paddy Field

  • Jeon, Ji-Hong;Yoon, Chun-G.;Hwang, Ha-Sun;Jung, Kwang-Wook
    • 한국농공학회지
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    • 제45권7호
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    • pp.57-69
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    • 2003
  • To evaluate nutrient dynamics with different fertilization in paddy field and develop water quality model, mass balance analysis was performed during growing season of 2001-2002 in field experimental plots irrigated with groundwater. As a result of water balance analysis, most of outflow was surface drainage as about half of total outflow and about 500mm was lost by evapotranspiration. The water budget was well balanced. The runoff from paddy field was influenced by rainfall and forced drain. Especially runoff during early cultural periods more depends on the forced drain. As a result of mass balance analysis, most of nutrient was input by fertilization and lost by plant uptake. Significant amount of nitrogen were supplied by precipitation and input from upper paddy field, comprising 12%∼28% of total inflow. Nutrient loading by surface drainage was occurred showing about 15%∼29% for T-N and 6%∼13% for T-P. The response of rice yield with different fertilization was not significant in this study. Water quality model for paddy field developed using Dirac delta function and continuous source was calibrated and validated to surface water quality monitoring data. It demonstrates good agreement between observed and simulated. The nutrient concentration of surface water at paddy field was significantly influenced by fertilization. During early cultural periods when significant amount of fertilizer was applied, surface drainage from paddy field can cause serious water quality problem. Therefore, reducing surface drainage during fertilization period can reduce nutrient loading from paddy fields. Shallow irrigation, raising the weir height in diked rice fields, and minimizing forced surface drainage are suggested to reduce surface drainage outflow.

T-50 착륙외장 형상에서 조종면 형상 재구성 모드의 항공기 비행 (A Study on Aircraft Flight Stability of T-50 Control Surface Reconfiguration Mode in PA Configuration)

  • 김종섭
    • 한국항공우주학회지
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    • 제34권3호
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    • pp.93-100
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    • 2006
  • 현대의 고성능 전투기에 탑재되어 있는 전기식 비행제어계통(Digital Fly-By-Wire Flight Control System)은 항공기 조종면의 고장으로 인해 발생할 수 있는 항공기의 안정성을 보장하기 위해 조종면 형상 재구성 모드(Control Surface Reconfiguration Mode)가 설계되어 있다. T-50 제어법칙에는 단일 조종면이 고장 났을 경우, 정상작동중인 나머지 조종면을 이용하여 항공기를 원활히 조종할 수 있도록 형상 재구성 모드가 적용되어 있다. 본 논문에서는 항공기 운용 시 발생할 수 있는 조종면 결함으로 인해 형상 재구성 모드 제어법칙이 적용되었을 경우, 착륙외장형상에서 항공기 안정성을 해석하기 위하여 선형해석(Linear Analysis)을 수행하였다 그리고 착륙에 대한 비행성(Flying Quality) 저하여부를 판단하기 위해, HQS(Handling Quality Simulator)를 이용하여 조종사 시뮬레이션을 수행하였다. 해석결과, 조종면 고장으로 인해 제어법칙이 형상 재구성 모드로 전환될 경우, 항공기의 조종성 및 비행성의 저하가 다소 발생하였지만, HQS 조종사 시뮬레이션 결과 착륙과정에서는 비행성 요구도인 Level 1을 만족할 수 있었다.

Evaluation on the Mechanical Performance of Low-Quality Recycled Aggregate Through Interface Enhancement Between Cement Matrix and Coarse Aggregate by Surface Modification Technology

  • Choi, Heesup;Choi, Hyeonggil;Lim, Myungkwan;Inoue, Masumi;Kitagaki, Ryoma;Noguchi, Takafumi
    • International Journal of Concrete Structures and Materials
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    • 제10권1호
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    • pp.87-97
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    • 2016
  • In this study, a quantitative review was performed on the mechanical performance, permeation resistance of concrete, and durability of surface-modified coarse aggregates (SMCA) produced using low-quality recycled coarse aggregates, the surface of which was modified using a fine inorganic powder. The shear bond strength was first measured experimentally and the interface between the SMCA and the cement matrix was observed with field-emission scanning electron microscopy. The results showed that a reinforcement of the interfacial transition zone (ITZ), a weak part of the concrete, by coating the surface of the original coarse aggregate with surface-modification material, can help suppress the occurrence of microcracks and improve the mechanical performance of the aggregate. Also, the use of low-quality recycled coarse aggregates, the surfaces of which were modified using inorganic materials, resulted in improved strength, permeability, and durability of concrete. These results are thought to be due to the enhanced adhesion between the recycled coarse aggregates and the cement matrix, which resulted from the improved ITZ in the interface between a coarse aggregate and the cement matrix.

RF-MBE 성장조건에 따른 InGaN 단결정 박막의 결정성 관찰 (Effect of Growth Conditions on Crystal Quality of InGaN Epitaxial Layers Grown by RF-MBE)

  • 나현석
    • 열처리공학회지
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    • 제31권5호
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    • pp.237-243
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    • 2018
  • In-rich InGaN epilayers were grown on (0001) sapphire substrates by radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE). InGaN epilayers grown at various growth condition were observed by SEM, XRD, and RHEED. When plasma power of nitrogen increased from 290 to 350 W, surface morphology and crystal quality became worse according to more active nitrogen on the surface of InGaN at N-rich growth condition. As In composition was reduced from 89 to 71% by changing the incoming flux of In and Ga, surface morphology and crystal quality became worse. In addition, weak peaks of cubic InGaN phase was observed from InGaN layer with 71% In composition by XRD ${\Phi}$ scan measurement. When growth temperature decreased from 500 to $400^{\circ}C$, RHEED diffraction pattern was changed to be from streaky to spotty which means atomically rough surface, and spotty pattern showed cubic symmetry of InGaN clearly. XRD ${\Phi}$ scan measurement gave clear evidence that more cubic InGaN phase was formed at low growth temperature. All these results indicates that extremely low surface mobility of Ga adatom caused inferior crystal quality and cubic InGaN phase.