• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1097-1100
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• 2004

A rear axle spider in an irregular shape, which is used as a part in the braking system of a vehicle like a big truck and a trailer, is subjected to a large torque and hence requires both strength and endurance over the brake heat. This part should be therefore manufactured in dimensional accuracy. The practical manufacturing process of this irregular product requires the heat treatment process after hot forging and then the cold coining process for the dimensional accuracy. At the present study, the warm coning without the heat treatment process was proposed to employ the residual heat due to the hot forging process. And also the trimming and piercing process was designed using the rigid-plastic finite element method. The mechanical properties were discussed and also commented upon.

• Communications for Statistical Applications and Methods
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• v.22 no.1
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• pp.95-103
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• 2015

We introduce a surplus process which follows a diffusion process with positive drift and is subject to two types of claim. We assume that type I claim occurs more frequently, however, its size is stochastically smaller than type II claim. We obtain the ruin probability that the level of the surplus becomes negative, and then, decompose the ruin probability into three parts, two ruin probabilities caused by each type of claim and the probability that the level of the surplus becomes negative naturally due to the diffusion process. Finally, we illustrate a numerical example, when the sizes of both types of claim are exponentially distributed, to compare the impacts of two types of claim on the ruin probability of the surplus along with that of the diffusion process.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.174-183
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• 2000

Non-Parallelism the axial direction occurs during grinding process of long slender shafts. The reason for the axial error is due to elastic deformation of the components, accumulation phenomenon of the grinding and wheel wear during the grinding process. The accumulation phenomenon, the size generation mechanism and the wheel wear process during traverse grinding result in complicated process at each step on the wheel surface. The grinding system stiffness obtained from the stiffness of the center on the tailstock and the workpiece varing according to the relative position of the wheel and the workpiece. Further more, the value of wheel wear increases as the grinding process advances. The above mentioned issues make the shape generation process during traverse grinding quite complicated. This research analyzes the shape generation process in the direction of the work spindle. First, the formulation of the grinding system stiffness was conducted and the simulation analysis method of the traverse grinding was established. Also, a measuring system for assessing the dimensinal accuracy of the workpiece has been developed.

• Journal of Powder Materials
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• v.11 no.4
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• pp.314-321
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• 2004

The elastic moduli of simulated dry process fuels with varying composition and density were measured in order to analyze the mechanical properties of a dry process fuel pellet. Resonant ultrasound spectroscopy(RUS) which can determine all elastic moduli with one set of measurements for a rectangular parallelepiped sample was used to measure the elastic moduli of UO$_{2}$ and simulated dry process fuel. The simulated dry process fuel showed a higher value of Young's modulus than UO$_2$ due to the presence of metallic precipitates and solid solution elements in the UO$_{2}$ matrix. The correlation between Young's modulus and porosity(P) of simulated dry process fuel was found to be 231.4-651.8 P (GPa) at room temperature. Dry process fuel with a higher burnup showed higher Young's modulus because total content of fission product element was increased.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.492-498
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• 2001

In the previous study, temperature monitoring of case about shrinkage fit process was performed and heat transfer model was developed in detail by feedback and tuning among monitoring result, process investigation, and analysis result. The gap element in contact between case and core was effectively used in analysis model. In present study, following things are performed to solve deformation of case due to shrinkage fit process on the basis of previous result. Above all, mechanical material properties of case are measured by case specimen for deformation analysis considering weldment of case. Deformation of case before and after shrinkage fit process is measured, too. Three dimensional deformation model is developed by the comparison and inspection between these experimental data and analysis results. Deformation analysis is simulated with the result of heat transfer analysis, in other words, non-coupled analysis is used. Finally the countermeasure for deformation is brought up through those.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.107-116
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• 1994

In the manufacturing of VLSI circuits, variations of device characteristics due to the slight differences in process parameters drastically aggravate the performances of fabricated devices. Therefore, it is very important to establish optimal process conditions in order to minimize deviations of device characteristics. In this paper, we used one-dimensional process simulator, SUPREM-II, and two dimensional device simulator, MINIMOS 4.0 in order to extract optimal process parameter which can minimize changes of the device characteristics caused by process parameter variation in the case of short channel nMOSFET and pMOSFET device. From this simulation, we have derived the dependence relations between process parameters and device characteristics. Here, we have suggested a method to extract process parameters from design trend curve(DTC) obtained by these dependence relations. And we have discussed short channel effects and device limitations by scaling down MOSFET dimensions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.1-7
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• 2015

In the present study, copper micromolds with a microhole array were precisely manufactured by a synchrotron LIGA process. Like in the traditional LIGA process, a deep X-ray lithography based on a synchrotron radiation was employed as the first manufacturing step. Due to the excellent optical performance of the synchrotron X-ray used, cylindrical micropillar arrays with high aspect ratio could be efficiently obtained. The fabricated microfeatures were then used as a master of the subsequent copper electroforming process, thereby resulting in copper micromolds with a microhole array. Thermoplastic hot embossing experiments with the copper micromolds were carried out for imprinting cylindrical microfeatures onto a polystyrene sheet. Through the hot embossing, the effect of embossing temperature and usefulness of the present manufacturing method could be verified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.62-65
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• 2003

VLM-ST process requires an additional human interaction due to the manual stacking and bonding. Hence, building time, building cost and the part quality are dependent on the skill of labor. In this present work, a novel rapid prototyping (RP) process, as an automatic VLM-ST (VLM-STA), has been proposed to improve building efficiency of VLM-ST process and reliability of products. The apparatus of VLM-STA is designed to embody the process. Several characteristics of the proposed process and the apparatus are discussed. In order to examine the efficiency and the applicability of the proposed process, various three-dimensional shapes, such as a piston and a human head shape, are fabricated on the apparatus.

• Journal of Korean Society for Quality Management
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• v.30 no.1
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• pp.22-46
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• 2002

Recently, increasing attention has been paid to building the software quality and software productivity due to ongoing software crisis. To overcome such problem, one of the many alternatives is to use the capability maturity model (CMM) suggested by the Software Engineering Institute(SEI), focusing on the improvement of software progress. This research is proposed the theoretical framework for CMM based on the previous studies, and review the status of software process on the software development organization. We then examine the impact of the software process capability on the organizational performance including financial measures and non-financial measures. Hypotheses on software process capability were tested 144 organizational units. The 62.5% of foreign companies are distribute to the second and third level, the Korean firms in this study are indicated the first level. Result indicate that maturity of software process may be served the key predictor of organizational performance, in particular the positive relationship between the software process and non-financial performance index such as customer service, IT Infrastructure, marketing, supplier and purchaser, production and operation.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.1
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• pp.173-183
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• 2011

Global logistics including Korea had developed at various fields through the developed IT technology. In addition, in changing into Internet based digital economy times, economic and logistics activities became extending into worldwide over the cross-border. Logistics activity performed by off-line rapidly changed in real environment. But, unfortunately business process modeling about the whole logistics was not happened, even though process modeling had done by transport stages or logistics entities. Therefore, it is difficult to grasp the whole logistics. Additional cost and time was requested due to no association between logistics entities and invisibility. So, this paper has to be process modeling for logistics industry domain. For objective modeling, work area shall be divided and it extracts general work process per each area. And then it defines subprocess of general work process. Cargo tracking in logistics industry domain means to grasp the status and present states at transportation or storage stage. This paper defines business process and data model for electronic processed work area using the UN/CEFACT standard modeling methodology.