• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1668-1671
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• 2005

Vulcanized natural rubber was pulverized using a single screw extruder in a non-cryogenic Solid Shear Extrusion process where rubber granulates were subjected to high compressive and shear stresses. The producted particles had diameters ranging from 40 to 1200$\{mu}m$. A principle used in this paper was developed in Russia. The development method for producing a polymeric material powder consists in compressing said material by shearing the material during a pressure increase and cooling. Consecutive breakdown is carried out by shearing the material during the pressure decrease and cooling.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.73-84
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• 1990

A burr has been defined as an undesirable projection of material formed as the result of plastic flow from a cutting or shearing operation. It is Unavoidable in all kinds of machining operation. This paper describe the burr formation mechanism which is based on the behavior of workpiece material during orthogonal machining of the clay on the milling machine. Specially in this report the rollover burr is dealt as a specific case of the chip formation in the final stage of cutting. The negative shear angle is introduced as an important features of burr formation. It is found that the burr formation process is divided into three stage-initiation, development of negative shearing, and formation of the burr with appropriate assumptions. Using above the burr formation mechanism, the size of burr can be estimated by cutting conditions.

• Transactions of Materials Processing
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• v.31 no.1
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• pp.23-28
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• 2022

Although the hole expansion test is currently the most commonly used method to evaluate the stretch flangeability of HSS, it has been criticized due to its poor repeatability and reproducibility for test results. This paper focuses on the development of a new measurement method to investigate the stretch flangeability of HSS. Two materials (DP590, DP980) were investigated with a hole expansion test and a developed test method. Test results showed that the developed test method could be used as one stretch flangeability test to help identify relevant parameters of the shearing process to avoid edge cracking.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.84-91
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• 1999

The goal of this study is to analyse the stress and the strain occurring within the work piece at the fine-blanking process and hence to assume the size direction and a distribution chart of the shearing stress as the penetration of the punch is being increased trough the application of the FEM. For this analysis we introduced the piece-wise linear method in the non linear structural analysis program for large deformation sheet metal forming and we defined it as the problem of the non linear contact. Therefore we modeled the above problems as quadratic-nodded axi-symmetrical elements for the character-istics of the work piece. From the result of this analysis it was found that the shearing stress is a great deal occurred on the surface of the work piece during the beginning process of the punch penetration and it's effect is expected to influence importantly for the formation of burnish because the deeper is the penetration of the punch in the narrow clearance zone. the greater is the degree of the strain stress.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.224-228
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• 2000

The piercing and blanking of thin sheet metal working is specified division in press die design and making. In order to prevent the detects, the optimum design of the production part, strip process layout, die design, die making and try out etc. re necessary the analysis of effective factors. For example, theory and practice of metal shearing process and its phenomena, die structure, machine tool working for die making, die materials and its heat treatment, metal working in industrial and its know how etc. In this study, we analyzed whole of data base, theoretical back ground of metal working process, and then performed the progressive die tryout with the screw press. This study regards to the aim of small quantity of production part's press working. Part 1 of this study reveals with production part and strip process layout design.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.244-252
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• 1994

The morphological changes of primary solid particles as a fuction of process time on Al-Si alloys during semi-solid state processing with a shear rate of 200s were studied. In hypereutectic Al-15.5wt%Si alloy, it was observed that primary Si crystals are fragmented in the early stage of stirring and morphologies of primary Si crystals change from faceted to spherical during isothermal shearing for 60 minutes. In quaternary Al-12.5wt%Si-2.9wt%Cu-0.7wt%Mg alloy system, it was observed both primary silicon and ${\alpha}$-alumunum particles. Microstructural evolution of primary Si crystals was similar to that of the hypereutectic Al-Si alloy but equiaxed ${\alpha}$-Al dendrites are broken into nearly spherical at the early stage of shearing and later stage of the isothermal shearing ${\alpha}$- Al particles are slightly coarsoned by Ostwald ripening. Mechanical properties of Al-Si-Cu-Mg alloy were compared to those from other processes (squeeze casting and gravity casting). After T6 heat treatment, comparable values of hardness were obtained while slightly lower compressive strength values were observed in rheocast alloy. The elongation, on the other hand, exhibited significant increasement of 15% over gravity cast alloy.

• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.189-193
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• 1997

Aspheric pick-up lenses are increasingly used in consumer products such as computer and multimedia, as their mass production has become possible owing to the injection molding process. However still much work needs to be done for more effective manufacture of aspheric lenses, one area of which is the in-line inspection of produced lenses. In this paper, we present a lateral-shearing interferometer that has specially been designed to have a high immunity to external vibration and atmospheric disturbance. The interferometer comprises four prisms. They are directly attached to each other using an immersion oil so that relative sliding motions between the prisms are allowed. Their relative displacement can readily generate necessary lateral-shearing and phase-shifting to determine the wavefront of the beam collimated by the lens under inspection. A special phase-measuring algorithm of arbitrary-bucket is adopted to compensate the phase-shifting error caused by the thickness reduction in the immersion oil. Zernike polynomial fitting has done for determinating quantitative aberration of aspheric pick-up lenses. The interferometer built in this work is robust to external mechanical vibration and atmospheric disturbance so that experimental results show that it has a repeatability of less than λ/100.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2C
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• pp.117-123
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• 2008

Disturbed and undisturbed decomposed granite soils with different weathering degrees were extracted and analyzed through a series of tests (CD test, constant P test, etc.) to assess their dilatancy characteristics. Here, dilatancy refers to the volume change that takes place during shearing. As a result, the decomposed granite soil dilatancy impact increased the mean effective stress while concurrently lowering the water content in drained shear tests. In the case of undisturbed decomposed granite soil, which has a lower weathering degree, the water content increased at specific limits during the shearing process. A linear relationship of ${\Delta}V_d/V_1=D{\cdot}(({\sigma}_1-{\sigma}_3)-{\sigma}_c)/{{\sigma}_m}^{\prime}$ forms between shearing-induced volume change and principal stress variance.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.35-39
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• 2000

The piercing and blanking of thin sheet metal working is specified division in press die design and making. In order to prevent the detects, the optimum design of the production part, strip process layout, die design, die making and try out etc. are necessary the analysis of effective factors. For example, theory and practice of metal shearing process and its phenomena, die structure, machine tool working for die making, die materials and its heat treatment, metal working in industrial and its know how etc. In this study, we analyzed whole of data base, theoretical back ground of metal working process, and then performed the progressive die tryout with the screw press. This study regards to the aim of small quantity of production parts press working. Part 1 of this study reveals with production part and strip process layout design.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.190-195
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• 2001

The piercing and blanking of thin sheet metal working is specified division in press die design and making. In order to prevent the defects, the optimum design of the production part, strip process layout, die design, die making and try out etc. are necessary the analysis of effective factors. For example, theory and practice of metal shearing process and it's phenomena, die structure, machine tool working for die making, die materials and it's heat treatment, metal working in field, their know how etc. are included in those factors. In this study, we analyzed whole of data base, theoretical back ground of metal working process, and then performed the progressive die tryout with the screw press.