• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2223-2233
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• 1996

The analytical solutions for the free vibration of cross-ply laminated composite cyllindrical shell with axial stiffeners(stringers) are presented usint the energy method. The stiffeners are taken to be smeared over the surface of shell with the smeared stffener theory. The effect of the parameters such as the stacking sequences, the shell thichness, the shell radius-to stringer depth ratio, the stringer depth-to width ratio, the shell length-to radius ratio are studied. By comparison with the previously published experimental results and the analytical results for the stiffened isotropic cylindrical shell and the unstiffened orthotropic composite laminated cylindrical shell, it is shown that natural frequencies can be determined with adequate accuracy.

• Journal of Biomedical Engineering Research
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• v.31 no.4
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• pp.321-327
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• 2010

Most of the ear shells of hearing aids are manufactured manually, and it is one of the reasons that the cost of the custom-made hearing aids can be increased. Thus it is required to manufacture the ready-made ear shell for the purpose of easy manufacturing and decrease in cost. In this study, we extract parameters in order to manufacture the ready-made ear shell for CIC type hearing aids and simulate to reconstruct the ear shell using the extracted parameters. To parameter extraction, we set up the eleven parameters for the ready-made ear shell based on anatomical characteristics of the ear canal, and we found values of the parameters from twenty-one impressions in their 20s and twelve impressions in their 60s using aperture detection and feature detection algorithms. Classifying the parameters by size, we also determine the parameters of ready-made ear shell into three types for people in their 20s and two types for people in their 60s. Each ready-made ear shell was simulated to reconstruct using figured parameters, and evaluated the rate of agreement with unused impressions for setting parameters. To evaluate the ready-made ear shell, we calculate the volume ratio and intersection between of the each impression and ready-made ear shell, and the intersection ratio using the intersection volume and ready-made ear shell volume. As a result, the volume ratio was about 70%, and volume match ratio was also up to 70%. It means that the ready-made ear shell we simulated is the significantly matched to impression.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.154-155
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• 2016

Oyster shell is light weighted and its strength characteristic is similar to sand. So we produced mortar test piece using grounded oyster shell powder under 0.5mm, which is a standard of fine aggregate, and reviewed strength properties according to water cement ratio. In our test, we used two kinds of oyster shell particles: below 0.6mm and 1.2~2.5mm. Water cement ratio is varied 40% to 100% and we found that flexural strength and compressive strength are decreased in higher water cement ratio.

• Korean journal of food and cookery science
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• v.33 no.2
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• pp.190-197
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• 2017

Purpose: The purpose of this paper was to analyze the physicochemical properties related to peeling rate of Korean chestnut. Methods: Analyses were carried out for weight, thickness, polyphenol, amino acid and peeling ratio for Korean chestnut. The correlation between these physicochemical components and peeling ratio of chestnut was measured. Results: The average of thickness for inner shell and outer shell was 0.66 mm and 0.93 mm, respectively. The average peeling ratio was 77.51%. A significant negative correlation was found between peeling ratio and thickness of the inner shell ($r=-0.80^{***}$, p<0.001). Analysis for the polyphenol composition of inner shell by HPLC was carried out and peaks 2 ($r=-0.56^*$, p<0.05), 11 ($r=-0.68^{**}$, p<0.01), 14 ($r=-0.52^*$, p<0.05), 28 ($r=-0.66^{**}$, p<0.01) showed a significant negative correlation with the peeling ratio. Conclusion: Thickness of chestnut inner shell was determined as the most influential factors of peeling.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.371-379
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• 1993

The wrinkling in the electromagnetic tube compression with a mandrel is remarkably smaller than that of the process without it. To analyze this phenomenon, the critical forming parameters such as the ratio of the clearance to the shell radius, the ratio of the thickness to the shell radius, and the ratio of the applied pressure to the standard pressure are introduced tp consider the effect of the mandrel, in addition to those of the thickness of shell and applied loads. The amplification ratio is also used to observe the magnitude of amplification. The results obtained by 2-D finite element method show that the initial imperfection embedded in the radius of cylindrical shell is the dominant factor to determine the final shape of the tube compression, and that the amplification ratio tends to have smaller values with the smaller clearance ratio and also with the larger thickness and pressure ratios.

• The Korean Journal of Zoology
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• v.8 no.1
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• pp.1-7
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• 1965

The short-necked clam is distributed widely in Korean tidal flats and it is a much an important bivalve quantitatively as to control the production of the tidal flat. The shell of this clam tends to show remarkable morphological variations depending on the habitat. Under a seemingly favorable condition for the growth , the color pattern of shell of the clam is clear and obvious and having less weight and elongated shape, the ratios of shell length to both height and width are small . On the contrary , when the environment appears to be an unfavorable one, the shell is found to be heavy and stunted with smudgy color pattern. If this correlation between could be a basis for the judgement in suitability of growth environment for the clam. In the Ikawazu Bay, Japan, it is revealed that the elongated shell is produced from the coast outside of the Bay (1) , the stunted from the esturay (2) and the intermediate from the floodgate area (3) and the middle of the Bay (4). Followings are the results obtained from the morphological investigation of the claim in this Bay. 1. Relationship between the shell length and the largest shell rib length is linear and between the shell length and the shell width is also linear but with a critical point at the shell length of 17-20 mm. The ratio between the width and the largest rib length at a given shell length increases with the order of 1, 3, 4, and 2. 2. A gradual decreases of the ratio of the shell length to the largest rib length is observed when the former is less than 17-18 mm, and this ratio increases with the shell of longer. Also there is a different range of this ratio in each different location ; the greatest range in 2, the smallest in 1 and 4 being in between. 3. A similar biometric finding is apparent with the ratio between the length and width of the shell and the order in value is 2, 4, 1 and 3. 4. The ratios between the length and the largest rib length of elongated and stunted shell are 0.84-0.86 and 0.89-0.92, respectively , and those between the length and width are 0.40-0.51 and 0.49-0.58, respectively. 5. Generally , the elongated short necked clam shells are products of the tidal flat of good circulation of sea water with high salinity and smaller fluctuations of salinity and temperature within a day. The stunted shells are produced for tidal flats of opposite of above conditions.

• Steel and Composite Structures
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• v.48 no.3
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• pp.263-273
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• 2023

This paper investigates dynamic characteristics of a graphene nanoplatelets reinforced composite (GNPRC) sandwich doubly curved shell based on the first-order shear deformation theory (FSDT) and Hamilton's principle. The sandwich doubly curved shell is fabricated from a core made of honeycomb materials sandwiched by composite GNPs reinforced face-sheets. Effective materials properties of composite face-sheets are assumed to vary based on Halpin-Tsai micromechanical models and rule of mixture. Furthermore, the material properties of honeycomb core are estimated using Gibson's formula. The fundamental frequencies of the shell are computed with changes of main geometrical and material properties such as amount and distribution type of graphene nanoplatelets, side length ratio, thickness to length ratio of and side length ratio of honeycomb. The Navier's technique is presented to obtain responses. Accuracy and trueness of the present model and analytical solution is confirmed through comparison of the results with available results in literature. It is concluded that an increase in thickness to length ratio yields a softer core with lower natural frequencies. Furthermore, increase in height to length ratio leads to significant decrease in natural frequencies.

• Computers and Concrete
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• v.25 no.5
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• pp.411-425
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• 2020

In this paper, the shell material has been taken as functionally graded material and their material quantity is located by the exponential volume fraction law. Moreover, the impact of ring supports around the shell circumference has been examined for their various positions along the shell axial length. These rings support restraints the radial displacement in the transverse direction. While the axial modal deformation functions have been estimated by characteristic beam functions and nature of materials used for construction of cylindrical shells. The fundamental natural frequency of cylindrical shell of parameter versus ratios of length- and height-to-radius for a wide range has been reported and investigated through the study. In addition, by increasing height-to-radius ratio resulting frequencies also increase and frequencies decrease on ratio of length-to-radius. Though the trends of frequency values of both ratios are converse to each other with three different boundary conditions. Also it is examined the position of ring supports with length-to radius ratio, height-to-radius ratio and varying the exponent of volume fraction. MATLAB software package has been utilized for extracting shell frequency spectra. The obtained results are confirmed by comparing with available literature.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.107-112
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• 2004

The combining abilities in the 5 newly evolved thermo tolerant breeds viz., SR6, SR7, SR8 SR9 and SR10 of silkworm Bombyx mori L. and their 15 hybrids were made in a line${\times}$tester crossing programme. Data were analysed for seven quantitative traits i.e., pupation rate, cocoon yield, cocoon weight, cocoon shell weight, cocoon shell ratio, filament length and raw silk percentage under optimum room temperature $(25{\pm}{1^{\circ}C})$ conditions (In case of high temperature $(36{\pm}{1^{\circ}C})$ stress conditions five economic traits except filament length and raw silk percentage) with 3 widely adapted testers i.e., KA, CSR2 and CC1 as lines (females) and testers (males) respectively. The performance at high temperature and low humidity conditions aye only taken into consideration for selecting the best lines/hybrids. Among the lines SR6 exhibited positive General combining ability (GCA) effects for pupation rate, cocoon yield, cocoon weight and cocoon shell ratio traits, followed by SR7 for pupation rate, cocoon yield and cocoon shell weight and cocoon shell ratio. Among testers, KA exhibited positive GCA effects for two quantitative traits cocoon yield, cocoon weight and CSR2 for cocoon shell weight and cocoon shell ratio under adverse temperature conditions. The hybrid SR6${\times}$CC1 and SR7${\times}$CSR2 exhibited significant positive Specific combining ability (SCA) effects for majority of the traits in high temperature stress conditions of rearing. The better parent value of heterosis(Heterobeltiosis) was exhibited by the hybrid SR6${\times}$CC1 for pupation rate, cocoon yield, cocoon weight and cocoon shell weight and SR7${\times}$CSR2 for all the trails evaluated under high temperature conditions. Based on the results, the lines SR6 and SR7 was judged as best combiners and the hybrids SR6${\times}$CC1 and SR7${\times}$CSR2 can be selected for commercial exploitation in tropical climate.

• Journal of Sericultural and Entomological Science
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• v.17 no.2
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• pp.155-160
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• 1975

The study was carried out to investigate the effects of various compositions of artificial diet for silkworms on the cocoon shell fibroin-hydrolyzing with the proteolytic enzyme. The obtained results are summarized as follows： 1. It was found that the fibroin-hydrolyzing ratio of the cocoon shell made by silkworms fed with artificial diets was lower than that of the cocoon shell made by silkworms fed with natural diet (mulberry leaf) 2. The amount of soybean meal in the artificial diet was negatively related to the sericin content of cocoon shell but it scarcely affected on the fibroin-hydrolyzing ratio. 3. The increase of sucrose in the artificial diet reduced the sericin content of cocoon shell but it didn't influence on the fibroin-hydrolyzing ratio. 4. A significant difference between male and female silkworms fed with artificial diets was found in the sericin content of cocoon shell but it was not approved in tile fibroin-hydrolyzing ratio. 5. The artificial diet containing 8 per cent of mulberry leaf powder increased the fbroin-hydrolyzing ratio more than that containing 10 per cent of mulberry leaf powder or that containing 8 per cent of mulberry leaf powder and a little of methionine did. 6. The artificial diet for all instars of silkworms increased the fibroin-hydrolyzing ratio more than the artificial diet for 1st to 3rd instars and natural diet (mulberry leaf) for the rest instars did.