• Title/Summary/Keyword: defect factor

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Microstructure change of large cast-forged product by heat treatment conditions (열처리 공정이 대형 주단조품의 조직변화에 미치는 영향)

  • Lee, M.W.;Lee, Y.S.;Lee, S.W.;Lee, D.H.;Kim, S.S.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.102-106
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    • 2009
  • Thermal energy control is a important factor in a large size casting and forging. Good control of thermal energy makes characteristics and defect of large cast-forged part, such as large sized forged shell. We have studied about not only large size ring forging process and after heat treatment by FEM simulation. Also, changes of temperature and microstructure for forged shell were predicted. Therefore, we can choose the proper heat treatment condition by FEA. The sectional properties confirmed by practical experiment and evaluation have presented possibilities of process design by computational analysis.

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Risk-based Test Case/Test Set Value Estimation Model (리스크 기반 테스트 케이스/테스트 세트 가치 추정 모델)

  • Kwon, Won-Il;Kim, Jong-Ku;Kwon, Ho-Yeol
    • Journal of Industrial Technology
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    • v.32 no.A
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    • pp.125-128
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    • 2012
  • In this paper, we proposed a prioritization method of test cases using a value estimation model of test sets, that are key elements for highly effective software testings as well as involve a large cost factor in software developments and maintenances. Based on previous studies, our idea includes introducing some practical factors of the test case prioritization which critically influence the value of a test case: Relative values of test sets before and after the test running, Average value of these two relative values, Severity of the defect, Risks that are covered, Frequency of use, Change related values, Systematic elicitations, etc. Finally we discussed the usefulness and the expected effects of the proposed scheme.

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Forecasting Total Marine Production through Multiple Time Series Model

  • Cho, Yong-Jun
    • Journal of the Korean Data and Information Science Society
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    • v.17 no.1
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    • pp.63-76
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    • 2006
  • Marine production forecasting in fisheries is a crucial factor for managing and maintaining fishery resources. Thus this paper aims to generate a forecasting model of total marine production. The most generally method of time series model is to generate the most optimal single forecasting model. But the method could induce a different forecasting results when it does not properly infer a model To overcome the defect, I am trying to propose a single forecasting through multiple time series model. In other word, by comparing and integrating the output resulted from ARIMA and VAR model (which are typical method in a forecasting methodology), I tried to draw a forecasting. It is expected to produce more stable and delicate forecasting prospect than a single model. Through this, I generated 3 models on a yearly and monthly data basis and then here I present a forecasting from 2006 to 2010 through comparing and integrating 3 models. In conclusion, marine production is expected to show a decreasing tendency for the coming years.

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Inferences for the Changepoint in Bivariate Zero-Inflated Poisson Model (이변량 영과잉-포아송모형에서 변화시점에 관한 추론)

  • Kim, Kyung-Moon
    • Journal of the Korean Data and Information Science Society
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    • v.10 no.2
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    • pp.319-327
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    • 1999
  • Zero-Inflated Poisson distributions have been widely used for defect-free products in manufacturing processes. It is very interesting to check the shift after the unknown changepoint. If the detectives are caused by the two different types of factor, we should use bivariate zero-inflated model. In this paper, likelihood ratio tests were used to detect the shift of changes after the changepoint. Some inferences for the parameters in this model were made.

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A Study on Oxygen Precipitation in Heavily Boron Doped Silicon Wafer (고농도 붕소의 도핑된 실리콘 웨이퍼에서의 산소석출에 관한 연구)

  • 윤상현;곽계달
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.9
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    • pp.705-710
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    • 1998
  • Intrinsic gettering is usually to improve wafer quality, which is an important factor for reliable ULSI devices. In order to generate oxygen precipitation in lightly and heavily boron doped silicon wafers with or without high $^75 As^+$ ion implantation, the 2-step annealing method was adopted. After annealing, the were cleaved and etched with th Wright etchant. The morphology of cross section on samples was inspected by FESEM(field emission scanning electron microscopy). The morphology of unimplanted samples was rater rough than that of the implanted. Oxygen precipitation density observed by an optical microscope in lightly boron doped samples was about 3$\times10^6/cm^3$. However, in heavily boron doped samples, the density of oxygen precipitation was largest at $600^{\circ}C$ in 1st annealing, and decreased abruptly until $800^{\circ}C$, But it increased slightly at $1000^{\circ}C$ and was independent with the implantation.

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Digital Contouring Control of Biaxial System (2축 디지틀 윤곽제어)

  • Lee, Gun-Bok;Ko, Tae-Geun
    • Proceedings of the KIEE Conference
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    • 1998.11b
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    • pp.435-437
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    • 1998
  • In this productive system, it needs to control the each axis motion harmoniously to perform accurately for the manufacturing, transporting and printing. Independent Axis Control usually used for this objection. However, if Independent Axis Control mismatched the parameter of each axis system or in the case of free curve tracking or the case of high speed control, there would be big contour error so that cannot achieve control objection. As a result, there is Contour Control method suggested to supply for this defect. This paper carried modeling of biaxial system and implemented Independent Axis Control & Contouring Control on straight line, circular, and coner path by simulation and experiment. If feedrate increased, contour error growed. In consequence, according to this factor, we introduced contouring controller, so we could find the fact that contour error was reduced more than that of independent axis control about each path.

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The Study on Activity Star Problem and Optimum Construction Method Through the Defect Case of Zero Energy House in the Existing Building (기축건물의 제로에너지 하우스 하자 사례를 통한 공종별 문제점 및 최적구축 방안에 관한 연구)

  • Kim, Sun-Geun;Kwon, Soon-Wook
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.4
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    • pp.262-270
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    • 2015
  • In this paper existing buildings, not a new buildings and house for living people not just a displaying and a viewing, created by the imagine effect or virtual simulation was applied various Active and Passive elements. After constructing zero-energy houses, through default case happened during operation period it is described problems and solutions about field part, work classification, installation by Location part, and Installation equipment part. Since then, to take advantage of this thesis, it's the purpose of this paper using as the baseline data for building a zero-energy house in another similar case.

Pressure-temperature limit curve for reactor vessel evaluated by ASME code

  • Jhung, Myung Jo;Kim, Seok Hun;Jung, Sung Gyu
    • Structural Engineering and Mechanics
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    • v.14 no.2
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    • pp.191-208
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    • 2002
  • A comparative assessment study for a generation of the pressure-temperature (P-T) limit curve of a reactor vessel is performed in accordance with ASME code. Using cooling or heating rate and vessel material properties, stress distribution is obtained to calculate stress intensity factors, which are compared with the material fracture toughness to determine the relations between operating pressure and temperature during reactor cool-down and heat-up. P-T limit curves are analyzed with respect to defect orientation, clad thickness, toughness curve, cooling or heating rate and neutron fluence. The resulting P-T curves are compared each other.

Influence of Flow Conditions on a Boundary Layer to the Near-Wake of a Flat Plat (평판 경계층 유동조건이 근접후류에 미치는 영향)

  • Kim, D.H.;Chang, J.W.
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1625-1630
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    • 2004
  • An experimental study was carried out to investigate influence of flow conditions on a boundary layer to the near-wake of a flat plate. The flow condition in the vicinity of trailing edge that is influenced by upstream condition history is an essential factor that determines the physical characteristics of a near-wake. Various tripping wires were used to change boundary layer flow condition of upstream at the freestream velocity of 6.0 m/sec. Measurements of the boundary layer and near-wake according to the change of upstream conditions were conducted by using both I-probe(55P14 for boundary layer) and X-probe(55P61 for wake). Normalized velocity profiles of the boundary layer were shown the flow types such as laminar boundary layer, transition, and turbulent boundary layer at 0.95C from the leading edge. The velocity and turbulence intensity profiles of the near-wake for the case of laminar boundary layer at the flat plate surface exhibited a defect and a double peak showing perfect symmetry, respectively.

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Losses Comparison and Analysis for Fault Modes of Grid-connected Photovoltaic System (계통연계형 태양광발전 시스템의 고장유형별 손실 비교분석)

  • So, Jung-Hun;Ko, Suk-Whan;Ju, Young-Chul
    • Journal of the Korean Solar Energy Society
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    • v.37 no.3
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    • pp.23-32
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    • 2017
  • This paper presents losses comparison and analysis results for different types of fault modes of grid-connected photovoltaic system generated for long-term operation. The approach of losses comparison and analysis by faults is to identify relationship between measured and estimated values of five loss factors which are quantified from irradiance to system output power. This paper presents the symptom results for faults such as snow, shading, sensor defect, blackout, soiling and so on from three years or more monitored data. These results will indicate that it is useful to develop fault detection and diagnosis tool to enhance capacity factor and save operation and maintenance cost of grid-connected photovoltaic system in the field.