• Journal of Advanced Marine Engineering and Technology
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• 제33권1호
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• pp.97-103
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• 2009

The process design of forward Extrusion and Upsetting of Axi-symmetric part has been studied in this paper. During the cold forging product; auto transmission Solenoid Valve part, the defects such as folding and under-fill can be appeared by the improperly controlled metal flow. In this study, to reduce the folding and under-fill the design of experiments has been used to find out the significant design variables in the design of forging process. This paper deals with an Process Planning with which designer can determine operation sequences even after only a little experience in Process Planning of Multi-Former products by multi-stage former working. The approach is based on knowledge-based rules, and a process knowledge-base consisting of design rules is built. Based on the systematic procedure of process sequence design, the forming operation of cold forged auto transmission Solenoid Valve part is analyzed by the commercial Finite Element program, DEFORM/2D.

• 한국정밀공학회지
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• 제20권4호
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• pp.29-38
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• 2003

This paper deals with an automated computer-aided process planning and die design system with which designer can determine operation sequences even after only a little experience in process planning and die design of multi former-bolt products by multi-stage former working. The approach is based on knowledge-based rules, and a process knowledge base consisting of design rules is built. Knowledge fur the system is formulated from plasticity theories, empirical results and the empirical knowledge of field experts. Programs for the system have been written in AutoLISP for AutoCAD with a personal computer. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FEM softwares, DEFORM and ANSYS, to form a useful package. The system is composed of four main modules. The process planning and die design module considers several factors, such as the complexities of preform geometry, punch and die profiles, specifications of available multi former, and the availability of standard parts. It can provide a flexible process based on either the reduction in the number of forming sequences by combining the possible two processes in sequence, or the reduction of deviation of the distribution and the level of the required forming loads by controlling the forming ratios. The system uses 2D geometry recognition and is integrated with the technology of process planning, die design, and CAE analysis. The standardization of die parts for multi former-bolt products requiring a cold forging process is described. The system developed makes it possible to design and manufacture multi former-bolt products more efficiently.

• 소성∙가공
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• 제13권4호
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• pp.359-364
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• 2004

In the multi-stage former, a manufacture of hexagonal fitting nut was generated in a defective products about 70∼80% in the industry field. Products generated in defects manufactured to be a machining about 60%. Additional process increased a product cost and decreased a product rate. Therefore, it is important to predict and design a preform reducing defective products in the early stage of process design. So in the study Defects for manufacturing hexagonal fitting nut verified a cause through the finite element simulation. To reduce a defective generation. a preform designed and a designed preform verified through the finite element simulation. In conclusion, a generated defects when a hexagonal fitting nut manufactured should reduce if a round dimension of preform reduced and a part of opposition angle distributed in plenty a volume.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.250-253
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• 1998

This paper presents a multi-modal neural network composed of a preprocessing module and a multi-layer neural network module in order to enhance the nonlinear characteristics of neural network. The former module is based on spectral method using Chebyschev polynomials and transforms input data into spectra. The latter module identifies the system using the spectra generated by the preprocessing module. The omnibus numerical experiments show that the method is applicable to many a nonlinear dynamic system in the real world, and that preprocessing using Chebyschev polynomials reduces the number of neurons required for the multi-layer neural network.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.983-987
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• 2001

This paper deals with an automated computer-aided process planning system by which designer can determine operation sequences even if they have little experience in process planning of wheel bolt products by a multi-stage former. The approach to the system is based on knowledge-based rules and a process knowledge base consisting of design rules is built. Knowledge for the system is formulated from plasticity theories, empirical results and the empirical knowledge of field experts. Programs for the system have been written in AutoLISP for the AutoCAD using a personal computer and are composed of two main modules. An attempt is made to link programs incorporationg a number of expert design rules to form a useful package. Results obtained using the modules enable the designer and manufacturer of wheel bolt product to be more efficient in this field.

• 소성∙가공
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• 제13권5호
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• pp.429-434
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• 2004

Manufacturing process for milli components has recently gained researcher's focus with the increasing tendency toward highly integrated and micro-scaled parts for electronic devices. The milli-components need more precise manufacturing process than the conventional manufacturing process since the parts require higher dimensional accuracy than the conventional ones. In order to enhance the forming accuracy and productivity, various forming procedures proposed and studied by many researchers. In this paper, forming analysis of milli-components has been studied with a new micro-former. In modeling of progressive dies, multi-stage forming sequence has been analyzed with finite element analysis by LS-DYNA3D. The analysis proposes the sequential die and part shapes with the corresponding punch force and dimensional accuracy. The analysis also considers the effect of elastic dies on the dimensional accuracy of the formed parts. The analysis result demonstrates that the elastic analysis in the milli-forming process is indispensable for accurate forming analysis. The analysis procedure in the paper will provide good information in design of a new micro-former and milli-component

• 소성∙가공
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• 제12권6호
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• pp.536-541
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• 2003

In this paper, the rigid-viscoplastic finite element method is employed together with an iteratively force-balancing method to analyze a piercing and trimming process with a spring-attached die in hot former forging. An actual piercing and trimming process with a spring-attached die is investigated in detail and a generalized analysis model is proposed. A multi-stage hot former forging process is simulated under various spring constants. The analyzed results are discussed in order to investigate the effects of spring constants on the metal flow lines and the formed shapes. Then an optimal piercing and trimming process in hot former forging is devised.

• 디지털산업정보학회논문지
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• 제5권4호
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• pp.87-97
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• 2009

Internet network routing system is used to prevent spread and distribution of malicious data traffic. This study is based on analysis of diagnostic weakness structure in the network security domain. We propose an improved integrated multi-level protection domain for in the internal route of groupware. This paper's protection domain is designed to handle the malicious data traffic in the groupware and finally leads to lighten the load of data traffic and improve network security in the groupware. Infrastructure of protection domain is transformed into five-stage blocking domain from two or three-stage blocking. Filtering and protections are executed for the entire server at the gateway level and internet traffic route ensures differentiated protection by dividing into five-stage. Five-stage multi-level network security domain's malicious data traffic protection performance is better than former one. In this paper, we use a trust evaluation metric for measuring the security domain's performance and suggested algorithm.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.97-100
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• 2003

Globally, the various machine components, as in electronics and communications, are demanded to being high-performance and micro-scale with abrupt development of the fields of computers, mobile communications. As this current tendency, production of the parts that must have high accuracy, so called milli-structure, are accomplished by the method of top-down, differently as in the techniques of MEMS, NANO. But, in the case of milli-structure, production procedure is highly costs, difficult and demands more accurate dimension than the conservative forming, processing technique. In this paper, forming analysis of the micro-former as the milli-structure are performed and then calculate the punch force etc. This information calculated is applied to decide the forming capacity of micro-former and design the process of forming stage, dimension of dies in another forming bodies. And, for the better precise forming analysis, elasto-plastic analysis is to be performed, then the consideration about effect of elastic recovery when punch and die are unloaded, have to be discussed in change of dimensions.

• 환경생물
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• 제35권4호
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• pp.461-467
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• 2017

Shrimps infected with WSSV(White Spot Syndrome Virus) generally exhibit white spots in their inner space of carapaces as an acute clinical sign. In an effort to identify the correlation between this acute clinical sign and the condition, the index factors (RNA/DNA concentration and ratio, trypsin activity) were analyzed. A total 580 farmed Fenneropenaeus chinensis and 130 Lithopenaeus vannamei were collected from western and southern fifteen outdoor ponds in Korea. The status of the white spot pathology was divided into four stages (stage 0, stage I, stage II, and stage III), in accordance with the clinical signs as to the size and area of white spots. A significant decrease in RNA concentration and RNA/DNA ratio for multi-infected fleshy prawn (WSSV and vibrio sp.) occurred during the stage III (the whole carapace is covered with a white spot). In particular, RNA/DNA ratio was significantly lower as $1.47{\pm}0.04$ than other groups. A similar trend was also found in the single infection (WSSV), but the decrease was less than the multi-infection. In the species comparison, both species were vulnerable to the multi-infection, but L. vannamei was more sensitive than F. chinensis(ANOVA, p<0.05): A significant decrease in RNA concentration and RNA/DNA ratio was first found in stage II for the former species, while it was found in stage III for the latter species. Trypsin activity was also showed a similar tendency with nucleic acid variation. Multi-infected shrimp showed drastically decrease of trypsin activity. According to the results, clinical signs of the white spot under carapace have an only physiological effect on shrimp if they covered entirely with white spots.