• (The)Study of the Eastern Classic
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• no.68
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• pp.173-208
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• 2017

This study sorted out the political methods of the typical shell-and-bone inscriptions during early Western Zhou, the shapes and arrangements of Chan, Chak, and Jak, and the characteristics and description methods of shell-and-bone characters and also investigated the formation backgrounds and changing patterns of shell-and-bone inscriptions with a focus on the transmitted literature and actual shell-and-bone inscriptions. First, the transmitted literature contained records saying that Gogongdanbu told fortunes by burning tortoise shells during Proto-Zhou, but no Bokgap from those days had been excavated yet. The content of the divination focused on the periods of Kings Wen, Wu, and Cheng of Zhou, and the shell-and-bone characters of Juwon contained much content about Jugong those days. Second, there were some differences in the processing methods between Bokgap and Bokgol, but their origin could basically be found in the Joyeongjang form during middle Shang. In addition, it was found that they directly accepted the Bukchon type of Seomseo during late Shang and the divination method of the Proto-Zhou culture. Third, all of Bokgaps had a set of square Chan and rectangular Chak installed on the back, whereas all of Bokgols had a set of circular Chan and vertically thin Chak and were in the shape of a cat's eye. In terms of the Chan, Chak, and Jak arrangement, the Bokgaps were similar to those of Yinxu during late Shang, whereas the Bokgols had the characteristics of the Joyeongjang type during middle Shang. Finally, there were differences in the description methods of shell-and-bone characters according to the arrangement methods of shell-and-bone inscriptions. Some rules were found according to each of the parts. Bokgaps were placed horizontally so that Gapsu would face sideways. The middle sections of Bokgols were mostly placed horizontally with the Byeongbu and Seonbu facing downwards at Golgu to write downwards from right to left. This method was estimated to have something to do with "Sigo" in the divination process in The Rites of Zhou. It was inferred that the perceptions of divination changed in the process of arranging the rites and music institutions during early Western Zhou.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.1
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• pp.25-31
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• 2018

In this study, the differences of holding power according to the shape and weight distribution of concrete weight used in shellfish shell fishery were investigated through the experiments. To investigate the differences in shape, five bar-shaped concrete weights with the same length and different cross-sectional shapes were produced. The sectional shape of each weight was square, triangle, circle, small cross, and large cross (SQ, TR, CI, CR-S, CR-L). Ten rectangular parallelepiped weights with different bottom area and cross-sectional area were produced. To investigate the differences by the weight distribution, the holding power on the square model (SQ) with six 50 g weights at different positions was investigated. All the holding power was obtained by measuring the tensile force generated when the concrete weight was pulled at a constant speed on the sand. As a result, there were no differences in holding power between the ten rectangular weights. However, the experiment on weights with different cross-sectional shapes showed differences in holding power. The holding power was higher in the order of CR-L > CR-S > CI > TR > SQ. In the weight distribution test, the holding power was higher as the front side of the weight was heavier. Generally, the frictional force is the same even if the shape is different, when two objects have the same value in the weight and the roughness. On the other hand, it seems to have a large impact when the shape of the bottom is deformed in the course of pulling the object. Particularly, the larger the degree of protrusion like cruciform weights, the more the holding power increased while deeply digging the bottom. It is also likely that the holding power increases as the front weight increases.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.630-648
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• 1992

The minimum weight design for simply-supported isotropic or symmetrically laminated stiffened cylindrical shells subjected to various loads (axial compression or combined loads) is studied by a nonlinear mathematical search algorithm. The minimum weight design in accomplished with the CONMIN optimizer by Vanderplaats. Several types of buckling modes with maximum allowable stresses and strains are included as constraints in the minimum weight design process, such as general buckling, panel buckling with either stingers or rings smeared out, local skin buckling, local crippling of stiffener segments, and general, panel and local skin buckling including stiffener rolling. The approach allows the consideration of various shapes of stiffening members. Rectangular, I, or T type stringers and rectangular rings are used for stiffened cylindrical shells. Several design examples are analyzed and compared with those in the previous literatures. The unstiffened glass/epoxy, graphite/epoxy(T300/5208), and graphite/epoxy aluminum honeycomb cylindrical shells and stiffened graphite/epoxy cyindrical shells under axial compression are analyzed through the present approach.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.379-395
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• 2021

For the complicated structural details in ships and offshore structures, the traditional hotspot stress approaches are known to be sensitive to the element variables of element topologies, sizes, and integration schemes. This motivated to develop a new approach for predicting reasonable hotspot stresses, which is less sensitive to the element variables and easy to be implemented the real marine structures. The three-point bending tests were conducted for the longitudinal attachments with the round and rectangular weld toes. The tests were reproduced in the numerical simulations using the solid and shell element models, and the simulation technique was validated by comparing the experimental stresses with the simulated ones. This paper considered three hotspot stress approaches: the ESM method based on surface stress extrapolation, the Dong's method based on nodal forces along a weld toe, and the proposed method based on nodal forces perpendicular to an imaginary vertical plane at a weld toe. In order to study the element sensitivities of each method, 16 solid element models and 8 shell element models were generated under the bending and tension loads, respectively. The element sensitivity was analyzed in terms of Stress Concentration Factors (SCFs) in viewpoints of two statistical quantities of mean and bias with respect to the reference SCFs. The average SCFs predicted by the proposed method were remarkably in good agreement with the reference SCFs based on the experiments and the ship rules. Negligibly small Coefficients of Variation (CVs) of the SCFs, which is measure of statistical bias, were drawn by the proposed method.

• Journal of Aquaculture
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• v.19 no.4
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• pp.275-280
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• 2006

Effect of the various sources of dietary additives on growth, body composition and shell color of abalone Haliotis discus hannai was investigated for 16 weeks. Forty juvenile abalone averaging 13.5 g were randomly stocked into 21 of 50 L plastic rectangular containers each. Eight kinds of additives were prepared for this study: four commercially available microalgae [Haeatococcus (Hae), Isochrysis galbana (Iso), Shizochytrium (Sch) and Spirulina (Spi)], three crustacean meals [krill meal (KM), shrimp head meal (Shm) and red crab meal (Rcm)], and green tea by-product (Gre). In addition, dry sea tangle (Dst), Laminaria japonica, as a control, was prepared. Casein, dextrin and a mixture corn oil and fish oil was protein, carbohydrate and lipid sources, respectively, in the experimental diets. The 2% each additive was included into the experimental diets. The experimental diets were fed to abalone once a day at the ratio of $1.5{\sim}2.0%$ total biomass of abalone with a little leftover throughout the 16-week feeding trial. Survival of abalone was not significantly (P>0.05) affected by the experimental diets. However, weight gain of abalone fed the all experimental diets containing the various sources of additives was significantly (P<0.05) higher than that of abalone fed the Dst diet. Weight gain of abalone fed the Spi diet was highest and Shi, KM and Iso diets in order. Shell length and the ratio of soft body weight to body weight of abalone was not significantly (P>0.05) affected by the experimental diets. However, shell width of abalone fed the all experimental diets containing the various sources of additives was significantly (P<0.05) higher than that of abalone fed the Dst diet. The shell color of abalone fed the Spi diet was improved the most distinctively and similar to that of natural abalone. Therefore, it can be concluded that the experimental diets with the various sources of additives (microalgae and crustacean meals) was effective to improve growth of abalone and dietary inclusion of Spirulina was most effective to improve shell color of abalone.

• Structural Engineering and Mechanics
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• v.2 no.4
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• pp.359-367
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• 1994

The stability behaviour of symmetrically laminated rectangular composite plates with loaded ends clamped and unloaded edges simply-supported, and subjected to uniform in-plane compression is investigated. A numerical and experimental investigation is presented in this contribution. The stacking sequence of the laminated glass/epoxy composite plates is symmetric about the middle surface and consists of 8-ply [0, 90, +45, -45]s lamination. Numerical predictions were obtained through the use of the finite element method. The above plates were modelled with 8-noded isoparametric layered shell elements. The effect of the input parameters such as the degree and forms of prescribed initial imperfection and the incremental step size required for incremental loading, on the convergence of the solution is thoroughly examined. Experimental results are presented for 10 test panels. All test panels were made from glass/epoxy unidirectional prepregs and have aspect ratio of 5.088. The laminate thicknesses were found to vary from 1.054 mm to 1.066 mm. Comparison of experimental data with predicted results show good correlation and give confidence in the finite element model.

• Structural Engineering and Mechanics
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• v.25 no.2
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• pp.239-268
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• 2007

This paper deals with optimal stacking sequence design of laminate composite structures. The stacking sequence optimisation of laminate composites is formulated as a combinatorial problem and is solved using Simulated Annealing (SA), an algorithm devised based on inspiration of physical process of annealing of solids. The combinatorial constraints are handled using a correction strategy. The SA algorithm is strengthened by embedding Tabu search in order to prevent recycling of recently visited solutions and the resulting algorithm is referred to as tabu embedded simulated Annealing (TSA) algorithm. Computational performance of the proposed TSA algorithm is enhanced through cache-fetch implementation. Numerical experiments have been conducted by considering rectangular composite panels and composite cylindrical shell with different ply numbers and orientations. Numerical studies indicate that the TSA algorithm is quite effective in providing practical designs for lay-up sequence optimisation of laminate composites. The effect of various neighbourhood search algorithms on the convergence characteristics of TSA algorithm is investigated. The sensitiveness of the proposed optimisation algorithm for various parameter settings in simulated annealing is explored through parametric studies. Later, the TSA algorithm is employed for multi-criteria optimisation of hybrid composite cylinders for simultaneously optimising cost as well as weight with constraint on buckling load. The two objectives are initially considered individually and later collectively to solve as a multi-criteria optimisation problem. Finally, the computational efficiency of the TSA based stacking sequence optimisation algorithm has been compared with the genetic algorithm and found to be superior in performance.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.19-33
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• 2014

Structural robustness refers to the ability of a structure to avoid disproportionate consequences to the original cause. Currently attentions focus on the concepts of structural robustness, and discussions on methods of robustness based structural design are rare. Firstly, taking basis in robust $H_{\infty}$ control theory, structural robustness is assessed by $H_{\infty}$ norm of the system transfer function. Then using the SIMP material model, robustness based design of grid structures is formulated as a continuum topology optimization problem, where the relative density of each element and structural robustness are considered as the design variable and the optimization objective respectively. Generalized elitist genetic algorithm is used to solve the optimization problem. As examples, robustness configurations of plane stress model and the rectangular hyperbolic shell model were obtained by robustness based structural design. Finally, two models of single-layer grid structures were designed by conventional and robustness based method respectively. Different interference scenarios were simulated by static and impact experiments, and robustness of the models were analyzed and compared. The results show that the $H_{\infty}$ structural robustness index can indicate whether the structural response is proportional to the original cause. Robustness based structural design improves structural robustness effectively, and it can provide a conceptual design in the initial stage of structural design.

• Composites Research
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• v.29 no.6
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• pp.347-352
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• 2016

This work presents the free vibration characteristics of laminated composite corrugated rectangular plates using the analytical method. Because it is very difficult to determine its mechanical behavior of 3-dimensional corrugated structures analytically, the equivalent homogenization model is adapted to investigate the overall mechanical behavior of corrugated structures. The corrugated element can be homogenized as an orthotropic material. Both the effective extensional and flexural stiffness of this homogenized equivalent orthotropic material are considered in the analysis. The present analytical results are validated by those obtained from 3D finite element analysis based on shell elements. The natural frequencies and global vibration mode shapes obtained from present analytical and finite element analysis are presented. Some numerical results are presented to check the effect of the geometric properties.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.507-514
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• 2003

Most of CAE analyses for injection molding have been based on the Mele Shaw's approximation: two-dimensional flow analysis. in some cases, that approximation causes significant errors due to loss of the geometrical information as well as simplification of the flow characteristics in the thickness direction. Although injection molding analysis software using three-dimensional solid elements has been developed recently, such as Moldflow Flow3D, it does not contain a deformation analysis function yet. The present work covers three-dimensional deformation analysis or injection molded plastic parts using solid elements. A numerical scheme for deformation analysis has bun proposed from the results of injection molding analysis using Moldflow Flow3D. The accuracy of the proposed approach has been verified through a numerical analysis of rectangular plates with various thicknesses in comparison with the classical shell-based approach. In addition, the reliability of the approach has also been proved through an industrial example. an optical plastic lens, in comparison of real experiments.