• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4508-4528
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• 2016

Widespread use of wireless networks has drawn attention to ascertain confidential communication and proper authentication of an entity before granting access to services over insecure channels. Recently, Truong et al. proposed a modified dynamic ID-based authentication scheme which they claimed to resist smart-card-theft attack. Nevertheless, we find that their scheme is prone to smart-card-theft attack contrary to the author's claim. Besides, anyone can impersonate the user as well as service provider server and can breach the confidentiality of communication by merely eavesdropping the login request and server's reply message from the network. We also notice that the scheme does not impart user anonymity and forward secrecy. Therefore, we present another authentication scheme keeping apart the threats encountered in the design of Truong et al.'s scheme. We also prove the security of the proposed scheme with the help of widespread BAN (Burrows, Abadi and Needham) Logic.

• Steel and Composite Structures
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• v.32 no.5
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• pp.595-610
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• 2019

This paper deals with the static and dynamic behavior of Functionally Graded Carbon Nanotubes (FG-CNT)-reinforced porous sandwich (PMPV) polymer plate. The model of nanocomposite plate is investigated within the first order shear deformation theory (FSDT). Two types of porous sandwich plates are supposed (sandwich with face sheets reinforced / homogeneous core and sandwich with homogeneous face sheets / reinforced core). Functionally graded Carbon Nanotubes (FG-CNT) and uniformly Carbon Nanotubes (UD-CNT) distributions of face sheets or core porous plates with uniaxially aligned single-walled carbon nanotubes are considered. The governing equations are derived by using Hamilton's principle. The solution for bending and vibration of such type's porous plates are obtained. The detailed mathematical derivations are provided and the solutions are compared to some cases in the literature. The effect of the several parameters of reinforced sandwich porous plates such as aspect ratios, volume fraction, types of reinforcement, number of modes and thickness of plate on the bending and vibration analyses are studied and discussed. On the question of porosity, this study found that there is a great influence of their variation on the static and vibration of porous sandwich plate.

• Steel and Composite Structures
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• v.48 no.2
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• pp.191-206
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• 2023

The present research investigates how micromechanical models affect the behavior of Functionally Graded (FG) plates under different boundary conditions. The study employs diverse micromechanical models to assess the effective material properties of a two-phase particle composite featuring a volume fraction of particles that continuously varies throughout the thickness of the plate. Specifically, the research examines the vibrational response of the plate on a Winkler-Pasternak elastic foundation, considering different boundary conditions. To achieve this, the governing differential equations and boundary conditions are derived using Hamilton's principle, which is based on a four-variable shear deformation refined plate theory. Additionally, the Galerkin method is utilized to compute the plate's natural frequencies. The study explores how the plate's natural frequencies are influenced by various micromechanical models, such as Voigt, Reuss, Hashin-Shtrikman bounds, and Tamura, as well as factors such as boundary conditions, elastic foundation parameters, length-to-thickness ratio, and aspect ratio. The research results can provide valuable insights for future analyses of FG plates with different boundaries, utilizing different micromechanical models.

• (The)Study of the Eastern Classic
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• no.34
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• pp.257-286
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• 2009

Yi, Hang-no said that taiji(=li) was Myeong-deok(illustrious virtue), the core of mind and heart, emphasizing the sides of superintendent and mysterious ability of li. It seems that he aimed to stress the upper status of li than qi, out of earlier general theory on mind and heart recognizing both li and qi consisted in the mind and heart. Through it, he wanted to say that only human being had moral mind like taiji and upper moral status than animals which human being should keep. The reason that Yi, Hang-no emphasized the difference between li and qi was because of a critical mind that the upper value of li than qi should not be changed and it would be the most dangerous situation if the value collapsed. Like this, Yi, Hang-no's attitude emphasizing li in his theory of mind and heart eventually aimed to explain the theory of Insim(Desire to be) and Dosim(Moral Mind). Yi, Hang-no's disciples testified that their teacher, Yi, Hang-no had cost his whole life to study the theory of Insim and Dosim. This means that Yi, Hang-no had tried to discriminate between Insim and Dosim, and to block private desires in Insim. The fact that Yi, Hang-no stressed the importance of the theory of Insim and Dosim had to do with the special situation that Western Power approached Joseon dynasty. Because Yi, Hang-no opposed the Westerner's moral consciousness for individual desires, against heavenly orders. To overcome the Western challenge, Yi, Hang-no strived to notice that taiji was the core of human mind. The point that Yi, Hang-no wanted to say was that Dosim(Moral Mind) was just the heavenly orders which human being couldn't disobey. Yi, Hang-no thought that Joseon couldn't defence Western flow without this theory of Insim and Dosim. Just after French invasion(1866), Yi, Hang-no was selected as a high-leveled bureaucrat, so he insisted his opinions for rejecting heterodoxy by the letters to the throne several times. The letters also contained his theory of Insim and Dosim mainly. Insisting fight against Western Power and prohibition of trade with Western Power, Yi, Hang-no eventually emphasized the king's right mind(Dosim) as a main and sole means to achieve all the goals he said. In conclusion, Yi, Hang-no's theory on mind and heart was as it is reflected in his letters to the throne. Therefore we can see that Yi, Hang-no's theory on mind and heart had harmonized with his movement to "Rejecting Heterodoxy".

• Steel and Composite Structures
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• v.25 no.2
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• pp.157-175
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• 2017

The novelty of this work is the use of a new displacement field that includes undetermined integral terms for analyzing thermal buckling response of functionally graded (FG) sandwich plates. The proposed kinematic uses only four variables, which is even less than the first shear deformation theory (FSDT) and the conventional higher shear deformation theories (HSDTs). The theory considers a trigonometric variation of transverse shear stress and verifies the traction free boundary conditions without employing the shear correction factors. Material properties of the sandwich plate faces are considered to be graded in the thickness direction according to a simple power-law variation in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. The thermal loads are assumed as uniform, linear and non-linear temperature rises within the thickness direction. An energy based variational principle is employed to derive the governing equations as an eigenvalue problem. The validation of the present work is checked by comparing the obtained results the available ones in the literature. The influences of aspect and thickness ratios, material index, loading type, and sandwich plate type on the critical buckling are all discussed.

• Steel and Composite Structures
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• v.31 no.5
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• pp.503-516
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• 2019

This work presents a dynamic investigation of functionally graded (FG) plates resting on elastic foundation using a simple quasi-3D higher shear deformation theory (quasi-3D HSDT) in which the stretching effect is considered. The culmination of this theory is that in addition to taking into account the effect of thickness extension (${\varepsilon}_z{\neq}0$), the kinematic is defined with only 4 unknowns, which is even lower than the first order shear deformation theory (FSDT). The elastic foundation is included in the formulation using the Pasternak mathematical model. The governing equations are deduced through the Hamilton's principle. These equations are then solved via closed-type solutions of the Navier type. The fundamental frequencies are predicted by solving the eigenvalue problem. The degree of accuracy of present solutions can be shown by comparing it to the 3D solution and other closed-form solutions available in the literature.

• Geomechanics and Engineering
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• v.18 no.1
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• pp.85-96
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• 2019

A free vibration analysis and wave propagation of triclinic and orthotropic plate has been presented in this work using an efficient quasi 3D shear deformation theory. The novelty of this paper is to introducing this theory to minimize the number of unknowns which is three; instead four in other researches, to studying bulk waves in anisotropic plates, other than it can model plates with great thickness ratio, also. Another advantage of this theory is to permits us to show the effect of both bending and shear components and this is carried out by dividing the transverse displacement into the bending and shear parts. Hamilton's equations are a very potent formulation of the equations of analytic mechanics; it is used for the development of wave propagation equations in the anisotropic plates. The analytical dispersion relationship of this type of plate is obtained by solving an eigenvalue problem. The accuracy of the present model is verified by confronting our results with those available in open literature for anisotropic plates. Moreover Numerical examples are given to show the effects of wave number and thickness on free vibration and wave propagation in anisotropic plates.

• Steel and Composite Structures
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• v.48 no.6
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• pp.693-708
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• 2023

Composite beams, two materials joined together, have become more common in structural engineering over the past few decades because they have better mechanical and structural properties. The shear connectors between their layers exhibit some deformability with finite stiffness, resulting in interfacial shear slip, a phenomenon known as partial shear interaction. Such a partial shear interaction contributes significantly to the composite beams. To provide precise predictions of the geometric nonlinear behavior shown by two-layered composite beams with interfacial shear slips, a robust analytical model has been developed that incorporates the influence of significant displacements. The application of a higher-order beam theory to the two material layers results in a third-order adjustment of the longitudinal displacement within each layer along the depth of the beam. Deformable shear connectors are employed at the interface to represent the partial shear interaction by means of a sequence of shear connectors that are evenly distributed throughout the beam's length. The Von-Karman theory of large deflection incorporates geometric nonlinearity into the governing equations, which are then solved analytically using the Navier solution technique. Suggested model exhibits a notable level of agreement with published findings, and numerical outputs derived from finite element (FE) model. Large displacement substantially reduces deflection, interfacial shear slip, and stress values. Geometric nonlinearity has a significant impact on beams with larger span-to-depth ratio and a greater degree of shear connector deformability. Potentially, the analytical model can accurately predict the geometric nonlinear responses of composite beams. The model has a high degree of generality, which might aid in the numerical solution of composite beams with varying configurations and shear criteria.

• Korean Journal of Heritage: History & Science
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• v.56 no.2
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• pp.12-26
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• 2023

Recently, 『Gyeongja(庚子)/Daetongryeok(大統曆)』(1600), a memorandum record of Yu Seong-ryong during the reign of King Seonjo(宣祖) of the Joseon Dynasty, was returned to Korea from Japan, and about 4,000 letters in cursive characters have been interpreted by Ro Seung-suk. The contents for 203 days written in the margin of 『Gyeongja(庚子)/Daetongryeok(大統曆)』 are mostly new, and are meaningful in understanding Yu's life and social association circumstances. There are daily routines of each day, contemporary figures, diseases and oriental medicine prescriptions. In particular, the combat record of Admiral Yi Sun-shin in 83 letters on the cover is very important to understand the situation in those days. It seems that the reason for writing the combat situations a year and a few months after Admiral Yi died in war was to honor his distinguished military service for a long time by King Seonjo's order according to the public opinion of the royal court. The record can be classified into two categories. First, Admiral Yi sighed when he heard about Yu's dismissal from the office in Gogeumdo, and was always alert with clear water on the boat after the Battle of Waekyo Castle. Second, he was killed by bullets shot by the enemy while directly encouraging battle, not listening to his men who tried to dissuade him from leading the naval battle at Noryang. This only contained contents of devoting his life desperately, which is an important proof of the theory of his death in war. It also contains nine methods for making liquor and another method that wasn't known to the public, and seems to include popular alcohol brewing methods or newly devised ones. In addition, there is a detail that Heo Jun, the author of 『Donguibogam』, introduced medicine to Yu, along with being unable to attend ancestral rites and relieving the poor written in red. There are also stories about Kang Hang(姜沆) returning to Korea after being captured by Japan and Lee Deok-hong(李德弘)'s son, who introduced Gugapseondo(龜甲船圖, the first picture of the Turtle Ship in Korea) to King Seonjo. In the light of the above, 『Gyeongja(庚子)/Daetongryeok(大統曆)』is an important historical record to empirically research not only figures related to Yu but also the circumstances of those days since it contains new facts that are not in the existing literature. In particular, the big accomplishment of this study is to correct the mistakenly known theory of Admiral Yi's suicide and to find out the new fact that Heo Jun provided medical information. In this respect, this book is expected to serve as a testament to the future study of the history and characters related to Yu in the mid-Joseon period.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.4
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• pp.65-72
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• 1999

This paper tried to find out the various symbolic meanings and functions of landscape elements which Capital City of Shilla Dynasty contains, and what is the symbolism and identity of the city. Basically, this research took the thought of the place and the theory of cognition on landscape as a research tool, and undertook the process of surveying the physical surroundings of the city such as mountains, forests, tumuluses, mountain fortress walls, etc. Especially, the study referenced to a myth, thought, and a tale related to them of the surroundings. The research scope in time had been reached to the year of BC 57 which is beginning year of Shilla Dynasty form AC 467 which is year of introduction of new urban block system delivered from Dang Dynasty of ancient China. The results of research showed symbolic meanings of mountains and forests which is surrounding the Shilla capital from 4 directions of east, west, south and north. Namely, it was the places that the king of the kingdom of Shilla decent into the earth from the heaven. Also, the tumuluses which are located on the center of the capital imitated the surrounding mountains in forms, meaned the place that the dead king rised to heaven. All of these symbolized the Capital City of Dynasty as a sacred city which linked the heaven to earth, and earth to heaven. Finally, this paper suggested the Kyongju which is one of the most representative historic and tourist city in Korea should reflect this kind of symbolic meaning of ancient Capital City of Shilla Dynasty in case of arranging the urban identity plan to promote the quality of urban environment of Kyongju.