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Study on the Free Surface Behavior Using the Lattice Boltzmann Method (격자볼츠만법을 이용한 자유수면 거동 특성 연구)

  • Jung, Rho-Taek
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.16 no.4
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    • pp.255-262
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    • 2013
  • The boltzmann equation is based on the particle distribution function while the Navire-Stokes equation based on the continuum theory. In order to simulate free surface flow, this paper used the Lattice Boltzmann Method of which is the discretized form. The detail study on the characteristics of the Lattice Boltzmann Method for the free surface simulation was investigated. The developed code was validated with the traditional dam breaking problem by tracking the front position of the water. A basic roles of density functions in the Lattice Boltzmann Method is discussed. To have an engineering applications, the simulation is also conducted the free surface behavior with an arbitrary wall geometry.

MATHEMATICAL MODELLING AND ITS SIMULATION OF A QUASI-STATIC THERMOELASTIC PROBLEM IN A SEMI-INFINITE HOLLOW CIRCULAR DISK DUE TO INTERNAL HEAT GENERATION

  • Gaikwad, Kishor R.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.19 no.1
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    • pp.69-81
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    • 2015
  • The present paper deals with the determination of temperature, displacement and thermal stresses in a semi-infinite hollow circular disk due to internal heat generation within it. Initially the disk is kept at arbitrary temperature F(r, z). For times t > 0 heat is generated within the circular disk at a rate of g(r, z, t) $Btu/hr.ft^3$. The heat flux is applied on the inner circular boundary (r = a) and the outer circular boundary (r = b). Also, the lower surface (z = 0) is kept at temperature $Q_3(r,t)$ and the upper surface ($Z={\infty}$) is kept at zero temperature. Hollow circular disk extends in the z-direction from z = 0 to infinity. The governing heat conduction equation has been solved by using finite Hankel transform and the generalized finite Fourier transform. As a special case mathematical model is constructed for different metallic disk have been considered. The results are obtained in series form in terms of Bessel's functions. These have been computed numerically and illustrated graphically.

Rate-User-Perceived-Quality Aware Replication Strategy for Video Streaming over Wireless Mesh Networks

  • Du, Xu;Vo, Nguyen-Son;Cheng, Wenqing;Duong, Trung Q.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.11
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    • pp.2103-2120
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    • 2011
  • In this research, we consider the replication strategy for the applications of video streaming in wireless mesh networks (WMNs). In particular, we propose a closed-form of optimal replication densities for a set of frames of a video streaming by exploiting not only the skewed access probability of each frame but also the skewed loss probability and skewed encoding rate-distortion information. The simulation results demonstrate that our method improves the replication performance in terms of user-perceived quality (UPQ) which includes: 1) minimum average maximum reconstructed distortion for high peak signal-to-noise ratio (PSNR), 2) small reconstructed distortion fluctuation among frames for smooth playback, and 3) reasonable average maximum transmission distance for continuous playback. Furthermore, the proposed strategy consumes smaller storage capacity compared to other existing optimal replication strategies. More importantly, the effect of encoding rate is carefully investigated to show that high encoding rate does not always gain high performance of replication for video streaming.

Transient neonatal diabetes mellitus caused by a de novo ABCC8 gene mutation

  • Kong, Jung-Hyun;Kim, June-Bum
    • Clinical and Experimental Pediatrics
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    • v.54 no.4
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    • pp.179-182
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    • 2011
  • Transient neonatal diabetes mellitus (TNDM) is a rare form of diabetes mellitus that presents within the first 6 months of life with remission in infancy or early childhood. TNDM is mainly caused by anomalies in the imprinted region on chromosome 6q24; however, recently, mutations in the ABCC8 gene, which encodes sulfonylurea receptor 1 (SUR1), have also been implicated in TNDM. Herein, we present the case of a male child with TNDM whose mutational analysis revealed a heterozygous c.3547C>T substitution in the ABCC8 gene, leading to an Arg1183Trp mutation in the SUR1 protein. The parents were clinically unaffected and did not show a mutation in the ABCC8 gene. This is the first case of a de novo ABCC8 gene mutation in a Korean patient with TNDM. The patient was initially treated with insulin and successfully switched to sulfonylurea therapy at 14 months of age. Remission of diabetes had occurred at the age of 16 months. Currently, the patient is 21 months old and is euglycemic without any insulin or oral hypoglycemic agents. His growth and physical development are normal, and there are no delays in achieving neurological and developmental milestones.

Seismic behavior of steel reinforced concrete special-shaped column-beam joints

  • Liu, Z.Q.;Xue, J.Y.;Zhao, H.T.
    • Earthquakes and Structures
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    • v.11 no.4
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    • pp.665-680
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    • 2016
  • This paper focuses on the study of seismic behavior of steel reinforced concrete special-shaped column-beam joints. Six specimens, which are designed according to the principle of strong-member and weak-joint core, are tested under low cyclic reversed load. Key parameters include the steel form in column section and the ratio of column limb height to thickness. The failure mode, load-displacement curves, ductility, stiffness degradations, energy dissipation capacity and shear deformation of joint core of the test subassemblies are analyzed. The results indicate that SRC special-shaped column-beam joints have good seismic behavior. All specimens failed due to the shear failure of the joint core, and the failure degree between the two sides of joint core is similar for the exterior joint but different for the corner joint. Compared to the joints with channel steel truss, the joints with solid web steel skeleton illustrate better ductility and energy dissipation capacity, but the loading capacity and stiffness are roughly close. With the increasing of the ratio of column limb height to thickness, the joints illustrate higher loading capacity and stiffness, better energy dissipation capacity, but worse ductility.

Putative Histone H2A Genes from a Red Alga, Griffithsia japonica

  • Lee, Yoo-Kyung;Lee, Hong-Kum
    • ALGAE
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    • v.18 no.3
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    • pp.191-197
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    • 2003
  • Histones are important proteins that interact with the DNA double helix to form nucleosome. Two putative histone genes, GjH2A-1 and GjH2A-2 were isolated from a red alga Griffithsia japonica. The putative open reading frame of GjH2A-1 and GjH2A-2 shared high similarity with the previously reported amino acid sequences of histone H2As. They have a motif consisting of seven amino acids A-G-L-Q-F-P-V, which matches the histone H2A motif [AC]-G-L-x-F-P-V. Phylogenetic trees were constructed from amino acid sequences of 38 histone H2As. The histone H2As were divided into two groups: major H2As and H2A.F/Z variants. The major histone H2A group consisted of animals, fungi, plants + green algae, and red algae H2A subgroups. The animal histone H2A subgroup was divided into vertebrates, echinoderms, nematodes, insects, and segmented worms H2As. The putative red algal histone genes, GjH2A-1 and GjH2A-2, constituted an independent lineage. This is the first report on red algal histone genes.

A case study on the content types and characteristics of global fashion YouTubers (글로벌 패션 유튜버의 콘텐츠 유형과 특성에 관한 사례연구)

  • Kim, Koh Woon;Kim, Yoon
    • The Research Journal of the Costume Culture
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    • v.28 no.3
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    • pp.389-407
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    • 2020
  • With YouTube's overwhelming share of the market, research on analyzing the types of content on YouTube is essential. An analysis of major global fashion YouTubers that the types of video content could be largely classified into three main categories: Fashion, beauty and daily life. The fashion category was subdivided into styling and fashion product review content type. The beauty category was subdivided into tutorials, beauty product reviews, and beauty tip content types. The daily life category was subdivided into daily sharing, consultation, and Q & A content types. Video content within fashion YouTuber channels is accompanied by expertise in fashion and beauty. At the same time, videos on daily life are uploaded, and through interactive communication with viewers, YouTubers form an intimate bond with subscribers. Content emphasizing entertainment, not just information delivery that introduces fashion products, is attracting growing interest among subscribers. This study analyzed the content of the increasingly popular fashion YouTuber channels and determined its important characteristics. The study makes a significant contribution to academic research by laying a foundation for future studies of YouTube content in the fashion field. Since differences in country of birth and race among YouTubers may influence content production, follow-up research will be conducted on the types and characteristics of domestic fashion YouTubers.

Behaviour and design of structural steel pins

  • Bridge, R.Q.;Sukkar, T.;Hayward, I.G.;van Ommen, M.
    • Steel and Composite Structures
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    • v.1 no.1
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    • pp.97-110
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    • 2001
  • Architectural steel structures with visible tension and compression members are becoming more prevalent as a popular form of construction that reflects the nature of the resistance to the applied loads. These members require the use of structural steel pins at their ends to ensure either axial tension or axial compression in the members. Structural pins have been used as a means of connection for centuries and it would appear that their behaviour is relatively well understood. However, the rules for the design of pins vary quite considerably from code to code and this has caused some confusion amongst consulting structural engineers operating internationally. To provide some insight into this problem, a comprehensive testing program has been carried to examine the influence of parameters such as pin diameter, material properties of the pin, thickness of the loading plates, material properties of the loading plates and the distance of the pin to the edge of the loading plates. The modes of failure have been carefully examined. Based on this study, modifications to current design procedures are proposed that properly take into account the different possible modes of failure.

Stochastic optimal control of coupled structures

  • Ying, Z.G.;Ni, Y.Q.;Ko, J.M.
    • Structural Engineering and Mechanics
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    • v.15 no.6
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    • pp.669-683
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    • 2003
  • The stochastic optimal nonlinear control of coupled adjacent building structures is studied based on the stochastic dynamical programming principle and the stochastic averaging method. The coupled structures with control devices under random seismic excitation are first condensed to form a reduced-order structural model for the control analysis. The stochastic averaging method is applied to the reduced model to yield stochastic differential equations for structural modal energies as controlled diffusion processes. Then a dynamical programming equation for the energy processes is established based on the stochastic dynamical programming principle, and solved to determine the optimal nonlinear control law. The seismic response mitigation of the coupled structures is achieved through the structural energy control and the dimension of the optimal control problem is reduced. The seismic excitation spectrum is taken into account according to the stochastic dynamical programming principle. Finally, the nonlinear controlled structural response is predicted by using the stochastic averaging method and compared with the uncontrolled structural response to evaluate the control efficacy. Numerical results are given to demonstrate the response mitigation capabilities of the proposed stochastic optimal control method for coupled adjacent building structures.

A Study on Boiling Heat Transfer in a Impinging Subcooled Water Jet System (충돌과냉수분류(衝突過冷水噴流)의 비등열전달(沸騰熱傳達)에 관한 연구(硏究))

  • Lee, G.J.;Lee, J.S.;Ohm, K.C.;Cho, Y.C.;Seo, J.Y.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.5 no.1
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    • pp.10-17
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    • 1993
  • This paper describes the boiling heat transfer phenomena to be divided into three regions, nonboiling, nucleate boiling and burn-out in the impinging subcooled water jet system. In the nonboiling region, Nusselt number is a function of Prandtl number, Reynolds number and ${\Delta}T_{sub}/T_{ast}$ In the nucleate boiling region, the heat flux increases with increment of the nozzle exit velocity. But the degree of liquid subcooling does not affect the shape of the nucleate boilng curve. The dimensionless correlations can be expressed in the form of $q{\ell}/K_f{\Delta}T_{ast}=C(Bo{\cdot}C_p{\cdot}{\Delta}T_{sat}/Vo^2)^m{\cdot}(Re/We)^n$. The burn-out heat flux increases linearly with increment of the nozzle exit velocity, but independs of degree of subcooling and the supplementary water height.

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