• 한국경영과학회지
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• 제18권3호
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• pp.151-157
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• 1993

In this paper, we investigate the effects of yield randomness for lot-sizing in a multi-stage production system. The practical importance of incorporating yield randomness into production models has been emphasized by many researchers. Yield randomness, especially in semiconductor manufacturing, poses a mojor challenge for production planning and control. The task becomes even more difficult if the demand for final product is uncertain. An attempt to meet the demand with a higher level of confidence forces one to release more input in the fabrication line. This leads to excessive work-in-process (WIP) inventories which cause jobs to spend unpredictably longer time waiting for the machines. The result is that it is more difficult to meet demand with exceptionally long cycle time and puts further pressure to increase the safety stocks. Due to this spiral effect, it is common to find that the capital tied in inventory is the msot significant factor undermining profitability. We propose a policy to determine the quantity to be processed at each stage of a multi-stage production system in which the yield at each stage may be random and may need rework.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.178-181
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• 2004

Heat treatment is one of important manufacturing process that determine the quality of the products. Because of a difference of mechanical property by heat treatment, It is necessary to This papers presents flow stress and yield point through tensile test. The goal of this study is to obtain the data of flow stress and yield point at martensite, bainite, ferrite/pearlite phase structure using SCM420, SCr420. The result of tensile test is satisfied and is expected to develop an available FEM analysis.

• 한국공작기계학회논문집
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• 제10권4호
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• pp.84-90
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• 2001

The electro-reheoligical(ER) effect refers to the abrupt change in viscosity in certain suspensions on application of an electric field. This paper presents experimental results on material properties of an ER fluids subjected to electrical fatigues. As a first step, two types of EF fluids are made of arabic gum and methyl cellulose(MC) choosing 25% of parti-cle weight-concentration. Following the construction of test mechanism for electrical durability of ER fluid, the dynamic yield shear stress and current density of the ER fluids are experimentally distilled as a function of electric field. The yield shear stress of operated ER fluids are distilled and compared with those of unused ER fluids.

• 소성∙가공
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• 제18권5호
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• pp.416-421
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• 2009

The applications of the aluminum alloy sheets to the auto-body panels are dramatically increasing for weight reduction of the automobiles. However, low formability of the aluminum alloy sheet compared to the steel sheet can be obstacles in tool manufacturing processes. Therefore, many of yield criteria for the anisotropic materials such as the aluminum alloy sheet have been observed. In this study, the biaxial tensile test and FLD test for the aluminum alloy sheet are performed. The results are compared with Hill's 1948 and Hill's 1990 models by means of theoretical predictions. Finite element analysis was also performed using the proposed method for the real panel.

• 산업경영시스템학회지
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• 제35권4호
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• pp.1-9
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• 2012

Decisions on reliability screening rules and burn-in policies are determined based on the estimated reliability. The variability in a semiconductor manufacturing process does not only causes quality problems but it also makes reliability estimation more complicated. This study investigates the nonuniformity characteristics of integrated circuit reliability according to defect density distribution within a wafer and between wafers then develops optimal burn-in policy based on the estimated reliability. New reliability estimation model based on yield information is developed using a spatial stochastic process. Spatial defect density variation is reflected in the reliability estimation, and the defect densities of each die location are considered as input variables of the burn-in optimization. Reliability screening and optimal burn-in policy subject to the burn-in cost minimization is examined, and numerical experiments are conducted.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.164-167
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• 2009

The applications of the aluminum alloy sheets to the auto-body panels are dramatically increasing for weight reduction of the automobiles. However, low formability of the aluminum alloy sheet compare to the steel sheet can be obstacles in tool manufacturing process. Therefore, much of yield criteria for the anisotropic material such as the aluminum alloy sheet have been observed. In this study, the biaxial tensile test and FLD test for the aluminum alloy sheet are performed. The results are compared with Hill's 1948 and Hill's 1990 model by means of theoretical predictions. Finite element analysis also performed using the proposed method for the real panel.

• 기술사
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• 제33권1호
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• pp.106-115
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• 2000

The effect of puffing treatments on the sensory qualities improving of Ginseng Extract were investigated in the good products for rejecting soil flavor as Ginseng foreign bad taste, through chemical analysis and actual manufacturing practice, the following results were obtained. Puffing treated<15kg / ㎠psi> ginseng has produced a marked increase in soluble solid, crude saponin yield to the extent of 10% and without soil taste as compared with control Ginseng. Optimum Ginseng ethanol extraction condition were 90$\^{C}$ for 8 hours, which was cheap operating cost and color, apperance, total solid yield of Ginseng extracted products. For 70% ethanol extraction in temperature range of 60∼90$\^{C}$ for 8 hours, the higher temperature resulted higher yields in solids and Ginsenoside Especially, GinsenosideRgl as most effective physiological function component yield was increased in 18% by puffed Ginseng than control Cinseng products. The Hunter's color, L. a and b values of Ginseng extract were 31.09, 21.9 and 49.5 and increase brown and red color value and total Δ Evalue.

• 한국정밀공학회지
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• 제16권11호
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• pp.98-105
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• 1999

As the IC(Integrated Circuit) has been densified and complicated, it is required to thorough process control to improve yield. Experts, for this purpose, focused on the process analysis automation, which is came from the strict data management in semiconductor manufacturing. In this paper, we presents the process analysis system that can analyze causes, for a output after processes. Also, the plasma etching process that highly affects yield among semiconductor process is modeled to predict a output before the process. To approach this problem, we use adaptively trained neural networks that exhibit superior accuracy over statistical techniques. And in comparison with methods in other paper, a method that history of trend for input data is considered is shown to offer advantage in both learning and prediction capability. This research regards CD(Critical Dimension) that is considerable in high integrated circuit as output variable of the prediction model.

• 한국염색가공학회지
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• 제33권4호
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• pp.309-316
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• 2021

Due to the rigid nature of the silicon carbide fiber(SiC), fiber damage occurs from the friction during the carding process. This damage not only lowers the spun yarn yield, but also lowers the heat resistance of the spun yarn, so that ultra-high heat resistant yarn cannot be manufactured. Therefore, in the carding process where the most friction between fiber and machine(wire, etc.) occurs, some factors were modified and tested, and as a result of measuring the change in physical properties, fiber damage decreased due to the wire angle or wire density, resulting in improved yield. The test method used to measure the yield of SiC fiber was the carbonization method, and the content of SiC fibers was calculated using the remaining amount after carbonization. Carbonization test was performed at air condition, 700℃, and for 2 hours. Analysis by SEM-EDX showed that the carbide was consistent with the composition of the SiC fiber.

• 산업공학
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• 제20권3호
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• pp.288-297
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• 2007

Success of semiconductor/LCD industry depends on its yield and quality of product. For the purpose, FDC (Fault Detection and Classification) system is used to diagnose fault state in main manufacturing processes by monitoring time series data collected by equipment sensors which represent various conditions of the equipment. The data set is segmented at the start and end of each product lot processing by a trigger event module. However, in practice, segmented sensor data usually have the features of data asynchronization such as different start points, end points, and data lengths. Due to the asynchronization problem, false alarm (type I error) and missed alarm (type II error) occur frequently. In this paper, we propose a robust process fault detection system by integrating a process event detection method and a similarity measuring method based on dynamic time warping algorithm. An experiment shows that the proposed system is able to recognize abnormal condition correctly under the asynchronous data situation.