• 소성∙가공
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• 제23권4호
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• pp.211-220
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• 2014

The outer race of a constant velocity (CV) joint having six inner ball grooves has traditionally been manufactured by multi-stage warm forging, which includes forward extrusion, upsetting, backward extrusions, necking, ironing and sizing, and machining. In the current study, a multi-stage cold forging process is examined and an assessment for replacing and modifying the conventional multi-stage warm forging is made. The proposed procedure is simplified to the backward extrusion of the conventional process, and the sizing and necking are combined into a single sizing-necking step. Thus, the forging surface of the six ball grooves can be obtained without additional machining. To verify the suitability of the proposed process, a 3-dimensional numerical simulation on each operation was performed. The forging loads were also predicted. In addition, a structural integrity evaluation for the tools was carried out. Based on the results, it is shown that the dimensional requirements of the outer race can be well met.

• 한국환경과학회지
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• 제27권1호
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• pp.1-10
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• 2018

A continuous process of persulfate oxidation and citric acid washing was investigated for ex-situ remediation of complex contaminated soil containing total recoverable petroleum hydrocarbons (TRPHs) and heavy metals (Cu, Pb, and Zn). The batch experiment results showed that TRPHs could be degraded by $Fe^{2+}$ activated persulfate oxidation and that heavy metals could be removed by washing with citric acid. For efficient remediation of the complex contaminated soil, two-stage and three-stage processes were evaluated. Removal efficiency of the two-stage process (persulfate oxidation - citric acid washing) was 83% for TRPHs and 49%, 53%, 24% for Cu, Zn, and Pb, respectively. To improve the removal efficiency, a three-stage process was also tested; case A) water washing - persulfate oxidation - citirc acid washing and case B) persulfate oxidation - citric acid washing (1) - citric acid washing (2). In case A, 63% of TRPHs, 73% of Cu, 60% of Zn, and 55% of Pb were removed, while the removal efficiencies of TRPHs, Cu, Pb, and Zn were 24%, 68%, 62%, and 59% in case B, respectively. The results indicated that case A was better than case B. The three-stage process was more effective than the two-stage process for the remediation of complex-contaminated soil in therms of overall removal efficiency.

• 한국의류산업학회지
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• 제24권4호
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• pp.418-430
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• 2022

This study aims to analyze consumers' purchase decision-making process of buying avatar fashion items on the Metaverse platform. Drawing on the connection between the self-expression tendency of the MZ generation and that of avatars in the Metaverse, this study uses a qualitative research method to analyze how consumers express their self-image through the appearance of their avatars. Unlike previous studies on the clothing purchase decision-making process, this study shows that purchasing and consumption behavior involve the following six stages: recognizing desire, collecting information, evaluating alternatives, making purchases, evaluating the consumption, and post-purchase action-taking. In the first stage of the purchase decision-making process, consumers' desire arises with self-image expression and confirmation. In the second stage, consumers have a high tendency to shop in the best item category. In the alternative evaluation stage, consumers tend to seek items that match their highest standard while considering their personal preferences. In the fourth stage, when making actual purchases, unplanned purchase behavior often occurs along with an active practice of alternative evaluation. In the fifth stage, the evaluation of the consumption shows that consumers achieve satisfaction by applying a style to their avatars that they are unable to try in the real world. In the last stage, consumers often use their purchases to communicate their various styles with other online consumers. Therefore, we conclude that the online purchase decision-making process differs from the offline process as it is divided into six stages.

• 산업경영시스템학회지
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• 제10권15호
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• pp.33-38
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• 1987

In establishing Multi-Stage Machining process inspection procedures, however, where costs of inspection md defective products are often directly measurable, a better method for formulating inspection plans is available. If one of the primary interest of a manufacturing concern is to maximize profits, then optimal inspection plans ought to be selected so as to minimize costs. This paper is aimed to find a methodology of optimal inspection planning in Multi-stage Machining process and to develope a proper algorithm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.540-545
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• 2002

The tight integration of the part design and process planning is very effective to high quality product development and cost effective manufacturing. Moreover, the integration in the early design stage, that is, the integration of the conceptual design and the conceptual process planning may take a big impact with the forecasting the alternative of the design and manufacturing. In this paper, the real field parts are studied about the relations among the Feature, Function, and Manufacturing Process taking the style of reverse engineering method, to found the base of the systematic computer system for the integrated product design and manufacturing process planning.

• 한국정보시스템학회지:정보시스템연구
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• 제15권2호
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• pp.125-152
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• 2006

The purpose of this study is to explore the process of knowledge creation at the infusion stage in IT adoption. Because of the lack of the prior research on the infusion and the process of individual knowledge creation we employed Grounded Theory Method which is a qualitative method for building a theory inductively. Collecting and analyzing data from 13 knowledge workers including medical doctors, project managers, and bankers, a process model is developed through the serial process of open, axial and selective coding. We conceptualized the knlowledge creation at the infusion stage as a social process where knowledge is expressed through private and public justifications. This study also found that organizational politics, top management supports, and organization strategy are important factors facilitating the knowledge creation process.

• 소성∙가공
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• 제12권8호
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• pp.702-709
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• 2003

In the automotive industry hydroforming of sheet metal pairs have received special attention because materials for various sheet metal components of vehicles have changed into the high strength steel, aluminum, and titanium blank having low formability. Uniform deformation over the whole region is a main advantage in the sheet hydroforming process. Because upper and lower parts could be produced simultaneously with one tool, hydroforming of sheet metal pairs is competitive in reducing the lead-time and development cost. In this paper, the multi-stage hydroforming process of sheet pair is proposed in order to increase the formability of a structural part like the oil pan shape. The upper die for forming oil pan shape is divided into two parts which can move separately. By the finite element simulation, the design parameters such as geometry of the tool and detailed specification of hydraulic pump were calculated and verified. For the strict comparison of the proposed process, the blank holding force is kept to a constant value during deformation by hydraulic valve. The deformed shape and strain distribution of the manufactured parts with the proposed process are compared with the results of simulation. In the multi-stage hydroforming process, maximum thickness strain was improved by more than 30 percent.

• 소성∙가공
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• 제11권2호
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• pp.155-164
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• 2002

One of the important steps on semi-solid forming Is the reheating process of raw materials to the semi-solid state. This Process is not only necessary to achieve the required SSM billet state, but also to contro1 the microstructure of the billet. In reheating process, the globule size is determined by the holding time of last heating stage. Therefore, some experiments to investigate the relationship between the mechanical properties and the holding time in the last heating stage was performed. The alloys used in this experiment were 357, 319 and A390 alloys. The experiments of reheating were performed by using an Induction heating system with the capacity of 50kw. This paper shows the evolution of the microstructure according to the holding time of last reheating stage. Furthermore, to evaluate the effect of globule size controlled by holding time in last heating stage uniaxial tension test was performed. The strain-stress curves were plotted according to the holding time.

• Communications for Statistical Applications and Methods
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• 제27권1호
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• pp.15-35
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• 2020

In research on behavioral studies, significant attention has been paid to the stage-sequential process for multiple latent class variables. We now explore the stage-sequential process of multiple latent class variables using the multivariate latent class profile analysis (MLCPA). A latent profile variable, representing the stage-sequential process in MLCPA, is formed by a set of repeatedly measured categorical response variables. This paper proposes the extended MLCPA in order to explain an association between the latent profile variable and the latent group variable as a form of a two-dimensional contingency table. We applied the extended MLCPA to the National Longitudinal Survey on Youth 1997 (NLSY97) data to investigate the association between of developmental progression of depression and substance use behaviors among adolescents who experienced Authoritarian parental styles in their youth.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1993년도 추계학술대회발표논문집; 서강대학교, 서울; 25 Sep. 1993
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• pp.175-184
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• 1993

Modeling the production process is a necessary and essential aspect of the production planning. This paper introduces a theoretical model of the multi-stage production process. A multi-stage production process is regarded as a network of interrelated production activities which use system exogenous inputs of goods in production and the intermediate products transfers between activities to produce final products. Our model is characterized by (1) a few of the production-related assumptions and (2) two types of elements "goods and activities" that are represented in terms of the network terminology. This model is different from the another multi-stage production models, so-called production network models in relation to the production-theoretical concept. It is not based on the concept of the production correspondence and the activity production functions, but the technology model of Koopmans. Koopmans.