• 농업과학연구
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• 제14권1호
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• pp.98-133
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• 1987

The mechanical and rheological properties of agricultural materials are important for engineering design and analysis of their mechanical harvesting, handling, transporting and processing systems. Agricultural materials, which composed of structural members and fluids do not react in a purely elastic manner, and their response when subjected to stress and strain is a combination of elastic and viscous behavior so called viscoelastic behavior. Many researchers have conducted studies on the mechanical and rheological properties of the various agricultural products, but a few researcher has studied those properties of rice plant, and also those data are available only for foreign varieties of rice plant. This study are conducted to experimentally determine the mechanical and the rheological properties such as axial compressive strength, tensile strength, bending and shear strength, stress relaxation and creep behavior of rice stems, and grain detachment strength. The rheological models for the rice stem were developed from the test data. The shearing characteristics were examined at some different levels of portion, cross-sectional area, moisture content of rice stem and shearing angle. The results obtained from this study were summarized as follows 1. The mechanical properties of the stems of the J aponica types were greater than those of the Indica ${\times}$ Japonica hybrid in compression, tension, bendingand shearing. 2. The mean value of the compressive force was 80.5 N in the Japonica types and 55.5 N in the Indica ${\times}$ Japonica hybrid which was about 70 percent to that of the Japonica types, and then the value increased progressively at the lower portion of the stems generally. 3. The average tensile force was about 226.6 N in the Japonica types and 123.6 N in the Indica ${\times}$ Japonica hybrid which was about 55 percent to that of the Japonica types. 4. The bending moment was $0.19N{\cdot}m$ in the Japonica types and $0.13N{\cdot}m$ in the Indica ${\times}$ Japonica hybrid which was 68 percent to that of the Japonica types and the bending strength was 7.7 MPa in the Japonica types and 6.5 MPa in the Indica ${\times}$ Japonica hybrid respectively. 5. The shearing force was 141.1 N in Jinju, the Japonica type and 101.4 N in Taebaeg, the Indica ${\times}$ Japonica hybrid which was 72 percent to that of Jinju, and the shearing strength of Taebaeg was 63 percent to that of Jinju. 6. The shearing force and the shearing energy along the stem portion in Jinju increased progressively together at the lower portions, meanwhile in Taebaeg the shearing force showed the maximum value at the intermediate portion and the shearing energy was the greatest at the portion of 21 cm from the ground level, and also the shearing strength and the shearing energy per unit cross-sectional area of the stem were the greater values at the intermediate portion than at any other portions. 7. The shearing force and the shearing energy increased with increase of the cross-sectional area of the rice stem and with decrease of the shearing angie from $90^{\circ}$ to $50^{\circ}$. 8. The shearing forces showed the minimum values of 110 N at Jinju and of 60 N at Taebaeg, the shearing energy at the moisture content decreased about 15 percent point from initial moisture content showed value of 50 mJ in Jinju and of 30 mJ in Taebaeg, respectively. 9. The stress relaxation behavior could be described by the generalized Maxwell model and also the compression creep behavior by Burger's model, respectively in the rice stem. 10. With increase of loading rate, the stress relaxation intensity increased, meanwhile the relaxation time and residual stress decreased. 11. In the compression creep test, the logarithmic creep occured at the stress less than 2.0 MPa and the steady-state creep at the stress larger than 2.0 MPa. 12. The stress level had not a significant effect on the relaxation time, while the relaxation intensity and residual stress increased with increase of the stress level. 13. In the compression creep test of the rice stem, the instantaneous elastic modulus of Burger's model showed the range of 60 to 80 MPa and the viscosities of the free dashpot were very large numerical value which was well explained that the rice stem was viscoelastic material. 14. The tensile detachment forces were about 1.7 to 2.3 N in the Japonica types while about 1.0 to 1.3 N in Indica ${\times}$ Japonica hybrid corresponding to 58 percent of Japonica types, and the bending detachment forces were about 0.6 to 1.1 N corresponding to 30 to 50 percent of the tensile detachment forces, and the bending detachment of the Indica ${\times}$ Japonica hybrid was 0.1 to 0.3 N which was 7 to 21 percent of Japonica types. 15. The detachment force of the lower portion was little bigger than that of the upper portion in a penicle and was not significantly affected by the harvesting period from September 28 to October 20. 16. The tensile and bending detachment forces decreased with decrease of the moisture content from 23 to 13 percent (w.b.) by the natural drying, and the decreasing rate of detachment forces along the moisture content was the greater in the bending detachment force than the tensile detachment force.

• 대한가정학회지
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• 제27권1호
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• pp.1-8
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• 1989

In order to investigate the mechanical properties such as tensile, bending, shearing, thickness and weight of the wool fabrics were measured by KES-F system. Samples were classified into blend ratio, weave type, fabric count. Blend ratio was classified into two groups, which are P/W blended fabric (p=63~65%, w=35~37%) and all wool fabric. Weave type was classified into four groups, which are plain, 3 harness twill, 4harness twill, satin. Cloth count was classified into three groups, which are loose, medium, tight. Statistical analysis was performed using T-test, F-test. The results were as follows; 1. There was significant difference in the thickness, tensile, bending, shearing according to the blend ratio. 2. According the weave, there was significant difference in the bending, weight and thickness in the P/W blended fabrics. There was significant difference in the tensile, weight, thickness, bending, shearing, shearing hysterisis (2HG) in the all wool fabrics. 3. There was significant difference in the shearing properties according to the fabric count.

• 한국생산제조학회지
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• 제25권3호
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• pp.177-181
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• 2016

Hot shearing is a method of producing various high-quality planar machine parts by using reduced punch load. In order to predict the results of this process, the deformation behavior of work material at elevated temperatures need to be studied. In this research, a tensile test was carried out for 5052 aluminum alloy at high temperatures of $240-540^{\circ}C$ and strain rates of 0.001-0.1/s. The results of the tensile tests were studied to predict the deformation of the alloy during the hot shearing process. The results showed that hot shearing within a temperature range of $340-440^{\circ}C$ and a strain rate rage of 0.001-01/s will be the most effective in reducing punch load and increasing the sheared edge in the case of 5052 aluminum alloy.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.19-22
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• 2004

Shearing including punching, blanking, trimming, slitting, etc is one of the most frequently used processes in sheet metal manufacturing. It has been widely using for manufacturing autobody, electronic components, aircraftbody, etc. In this paper, it has been researched by the experimental investigation to examine the influence of shearing processes parameters such as clearance, cutting angle, material properties, etc. From the results of experiment, it has shown that it gives the small variations at burr height below the proper clearance and it also presents that it is no affected the variations of cutting angle.

• 수산해양기술연구
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• 제16권2호
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• pp.61-67
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• 1980

Previously, we had experimented on the model of stow net under the various combination including water velocity, spherical floats and elevating floats with the shearing hoods instead of the upper beam, however we couldn't concern with their characteristics. Spherical floats maintain their buoyancy at the same level when the speed increases, only the drag increases and effects some reduction in the fishing height. To eliminate this shortcoming, floats have to some hydrodynamic lifting force which increases with increasing speed. Phillips float with a dish-shaped metal plate welded on at the lower part and synthetic upthrusting float were used for the experiment to compare with their characteristics. Six kinds of model shearing hood depend on the angle of attack were used to test the characteristic of the shearing hood. According to their results, when the angle of attack is 30\ulcorner, the lift and drag coefficient reveal 1. 36, 0.84 respectively. And also experimented on the 5X8cm shearing hood to investigate the suitability for the model stow net.

• Current Optics and Photonics
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• 제7권6호
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• pp.692-700
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• 2023

We present a method for improving the accuracy of the modal wavefront reconstruction in the radial shearing interferometers (RSIs). Our approach involves expanding the reduced radial terms of Zernike polynomials to high-order, which enables more precise reconstruction of the wavefront aberrations with high-spatial frequency. We expanded the reduced polynomials up to infinite order with symbolic variables of the radius, shearing amount, and transformation matrix elements. For the simulation of the modal wavefront reconstruction, we generated a target wavefront subsequently, magnified and measured wavefronts were generated. To validate the effectiveness of the high-order Zernike polynomials, we applied both low- and high-order polynomials to the wavefront reconstruction process. Consequently, the peak-to-valley (PV) and RMS errors notably decreased with values of 0.011λ and 0.001λ, respectively, as the order of the radial Zernike polynomial increased.

• 한국정밀공학회지
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• 제24권8호통권197호
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• pp.81-88
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• 2007

This paper presents the development of a new inchworm actuation system using the shearing deformation of the piezoelectric actuators. In this new actuation system, piezoelectric shearing/expanding actuators, an inertial mass and an advanced preload system are configured innovatively to generate the motion of an inertial mass. There are two modes in the new actuation system: (1) stick mode, and (2) clamp mode. In stick mode, the deformation of the piezoelectric shearing actuators drives an inertial mass by means of the friction force at their contact interface. On the other hand, in clamp mode, the piezoelectric expanding actuators provide the gripping force to an inertial mass and, as a result, eliminate its backward motion following the rapid backward deformation of the piezoelectric shearing actuators. To investigate the feasibility of the proposed new actuation system, the experimental system is built up, and the static performance evaluation and dynamic analysis are conducted. The open-loop performance of the linear motion of the proposed new actuation system is evaluated. In dynamic analysis, the mathematical model for the contact interface is established based on the LuGre friction model and the equivalent parameters are identified.

• 동력기계공학회지
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• 제11권3호
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• pp.47-52
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• 2007

Punching, blanking, trimming and slitting are widely used in shearing processes in sheet metal forming of automotive parts. In this paper the effects of clearance, cutting angle and tool sharpness on the formation of burr were investigated by experimental method in shearing processes of steel sheets, SPCEN and SPRC35E. The amount of burr and the shapes of burr were different between two kinds of steel sheets. It has been shown that the cutting angle of the shearing blade had no effects on the height of burr when the clearance was below the 10% of the steel sheet thickness, and also that the height and shape of burr were not affected by the cutting angle when the wear of shearing blade was below the 10% of the steel sheet thickness. It was known that there had been existing the critical clearance of 10 to 15% for the tested steel sheet, SPCEN and SPRC35E.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1669-1673
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• 2004

Milk yield, lamb birth weight and weaning weight responses to shearing during winter in sheep were investigated. A total of 46 Karayaka ewes were allocated into two treatment groups. Pregnant ewes in one group were shorn on day 100 of gestation (Shorn, n=24) and the remaining ewes were left unshorn to serve as controls (Unshorn, n=22). The ewes were maintained on pasture during the day and housed in the evenings. Lamb birth weight, weaning weight and ewes'' daily milk yield in fifteen dayintervals until weaning (75 days) were recorded. Shearing ewes on day 100 of pregnancy increased gestation length (p<0.01) compared to unshorn ewes (147.8${\pm}$0.45 vs. 145.9${\pm}$0.42 days). Birth weights of lambs from shorn ewes on day 100 of their pregnancy were higher (p<0.01) than those from unshorn ewes (3.7${\pm}$0.11 vs. 3.2${\pm}$0.07 kg). Shearing pregnant ewes increased (p<0.05) the lamb weaning weight at day 75 post-lambing (23.6${\pm}$1.10 vs. 19.5${\pm}$0.91). It also increased milk yield (p<0.05). Milk yields on day 75 of lactation were 302${\pm}$33 and 425${\pm}$25 g per day for unshorn and shorn ewes on day 100 of pregnancy, respectively. Lamb survival at weaning was higher (p<0.05) in lambs from shorn ewes compared to those from unshorn ewes. In conclusion, shearing pregnant ewes in winter months enhanced milk yield, lamb birth weight, lamb weaning weight and lamb survival. It is suggested that increasing both lamb birth weight and subsequent milk yield of dams by shearing ewes on day 100 of pregnancy during winter may improve postnatal lamb viability.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2000년도 봄 한국섬유공학회 학술발표회 논문집(Proceedings of the Korean Textile Conference)
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• pp.177-180
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• 2000