• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.4
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• pp.300-306
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• 2019

Transmission cross section(TCS) is described analytically as $2G{\lambda}^2/4{\pi}$ irrespective of the aperture shapes for various transmission resonant apertures, such as small ridged circular or H-shaped, U-shaped, or Jerusalem cross-shaped apertures in an infinite thin conducting plane. The proposed expression is validated by comparison with the numerical results obtained from the method of moments(MOM). The TCS characteristics of the transmission resonant cavity structure in a thick conducting plane are also studied and the equivalence between the two small aperture structures is reported from the viewpoint of transmission efficiency.

• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.231-241
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• 2015

The direct strength method (DSM) has been adopted by the NAS (2004) and AS/NZS 4600 (2005) for the design of cold-formed steel members. The method can be successfully applied to the design of welded steel members. This paper reviews the development of the DSM for welded steel structural members. The design strength formulae for welded section columns and beams for the DSM are based on the test results performed on welded H-section, C-section, circular and rectangular hollow section columns, plate girders and stiffened plates. The comparison between the design strength of welded sections predicted by the DSM and that estimated by existing specifications is also provided. The comparison verifies that the DSM can properly predict the compressive, flexural and shear strength of welded section columns and beams with the interaction between local and overall buckling.

• The Korean Journal of Physiology
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• v.7 no.2
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• pp.49-58
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• 1973

The distensibility of the major arteries has been investigated extensively, but the value expressed as Young Modulus varies widely by the different schools of the investigators, the major reason undoubtedly being the difficulties encountered in the measurement. In the present study, an attempt was made to elucidate the distensibility of the external carotid artery of the rabbit, which was placed in saline immediately after removing from the apparently healthy, normal rabbit without anesthesia. The circular section strip and longitudinal section strip were made from the whole artery, and Young Modulus of the whole artery, circular section and longitudinal section strips was calculated from the length-tension curve of each sample. Also, the similar samples of the artery seperately obtained were placed in ATP solution in the concentration of 0.15 mM and 0.30 mM, and Young Modulus was similary calculated. Experiments were performed at 15,45 and 75 min after the artery was removed from the rabbit, and the results thus obtained are summarized as follows. 1) Young Modulus of the whole external carotid artery of the rabbit in saline was $4.74{\times}10^7dyne/cm^2$ at 15 min, but lower values were obtained at 45 and 75 min, Young Modulus being $4.62{\times}10^7dyne/cm^2\;and\;4.13{\times}10^7dyne/cm^2$, respectively. When the arterial samples were placed in ATP solutions, Young Modulus did not change much throughout the experiment, and lower Young Moduli were obtained in 0.30 mM ATP solution than in 0. 15 mM ATP solution. 2) Young Modulus Of the Circular Section Strip in Saline was $4.11{\times}10^7dyne/Cm^2,\;3.75{\times}10^7dyne/cm^2\;and\;3.90{\times}10^7dyne/cm^2,$ respectively, at 15, 45 and 75 min, the value at 15 min being the highest. However, when the strip was placed in ATP solutions, no appreciable change was observed throughout the experiment, and Young Moduli were lower in 0.30 mM ATP solution than in 0.15 mM ATP solution. 3) Young Modulus of the longitudinal section strip in saline was $2.12{\times}10^7dyne/cm^2,\;2.48{\times}10^7dyne/cm^2\;and\;2.46{\times}10^7dyne/cm^2$, respectively, at 15, 45 and 75 min, Young Modulus being slightly elevated in the latter part of the experiment. A similar tendency was observed when the strip was placed in ATP solutions.

• Plant Journal
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• v.15 no.4
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• pp.43-51
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• 2019

The stress concentration of the integral welded attachments (IWA) often used to support piping system has been a big issue because it induces local stresses in piping. The method to evaluate local stresses associated with attachments on elbows has been suggested in EPRI TR-107453. However, there are limitations regarding specific parameters range in order to use correlation equation. In this paper, parametric study based on piping elbow size and attachment dimension was performed utilizing finite element analysis (FEA) to evaluate the secondary stress indices of hollow circular cross section welded attachments on piping elbows with the extended parameters range. The results of the FEA were used to develop correlation formulas for calculating secondary stress indices. The empirical equations in this study are suggested as an alternative evaluation method of EPRI TR-107453 by extending parameters range.

• Journal of Korean Society of Steel Construction
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• v.29 no.4
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• pp.291-301
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• 2017

Most of current representative design standards worldwide forbid or impose restrictions on the use of high-strength steels for hollow tubular structures. The mechanical background of these limitations appears unclear and unduly conservative, and their validity needs to be re-evaluated. In this study, a total of 9 CHS(Circular Hollow Section) X-joints were tested under axial compression and analyzed to examine if the high-strength steel restrictions specified by current design standards could be relaxed. All the high-strength steel CHS X-joints tested showed satisfactory performance compared to ordinary steel joints in terms of serviceability, ultimate strength, and ductility, although the yield strength of steel was even as high as 800MPa.

• Journal of Korean Society of Steel Construction
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• v.8 no.4 s.29
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• pp.85-94
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• 1996

This paper investigated structural behaviors of joint of concrete filled steel tube column and P.C reinforced concrete beam through a series of hysteretic behavior experiment. The results are summarised as follows: (1) The joint stiffness of concrete filled square steel tube column and P.C reinforecd beam was higher than that of concrete filled circular steel tube column and P.C reinforecd beam, and it was decreased as the increase of the number of hysteretic cycle. (2) The aspects of the hysteretic behavior in the joint was stable as the increase of the number of hysteretic cycle, and rotation resisting capacity of joint of concrete filled square steel tube column and P.C reinforced concrete beam was higher than those of the concrete filled circular steel tube column and P.C reinforced concrete beam. (3) Some restriction must be put upon the ratio of axial force in this joint model because the load carrying capacity was decreased by flexural and flexural-torsional buckling in case of the ratio of axial force 0.6. (4) The emprical formula to predict the ultimate capacity of joint model to superimpose shearing strength of steel web(H section) and bending strength of reinforced concrete beam was expected.

• Korean Journal of Plant Taxonomy
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• v.35 no.2
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• pp.115-127
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• 2005

Two anatomical features of leaves, transverse section of midribs and petioles, were examined for nine species of five genera of Thymelaeaceae, Daphne L. -4 spp., Diarthron Turcz. -1 sp., Edgeworthia Meisn. -1 sp., Stellera L. -1 sp., Wikstroemia Endl. -2 sp., using light microscopy and scanning electron microscopy. In terms of shape of upper side, three types were observed, i.e., flattened, depressed, and raised. Outline of petioles is mostly semi-circular or circular in transverse section, with two distinct wings/weakly developed wings or without wings. Other characters besides anatomical features of leaves such as vascular bundle tissues, crystal, tannin are also described in details. Finally, we briefly discussed the systematic significance of the anatomical features of leaves for identification of Korean Thymelaeaceae.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.4
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• pp.25-34
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• 1986

A two-dimensional linear method has been developed for the motion and the second-order steady force arising from the hydrodynamic coupling between waves and currents in the presence of a body of arbitrary shape. Interaction between the incident wave and current in the absence of the body lies in the realm beyond our interest. A Fredholm integral equation of the second kind is employed in association with the Haskind's potential for a steadily moving source of pulsating strength located in or below the free surface. The numerical calculations at the preliminary stage showed a significant fluctuation of the hydrodynamic forces on the surface-piercing body. The problem is approximately solved by using the asymptotic Green function for $U^2{\rightarrow}0$. The original Green function, however, is applied for the fully submerged body. Numerical calculations are made for a submerged and for a half-immersed circular cylinder and extensively for the mid-ship section of a Lewis-form. Some of the results are compared with other analytical results without any available experimental data. The current has strong influence on roll motion near resonance. When the current opposes the waves, the roll response are generally negligible in the low frequency region. The current has strong influence on roll motion near resonance. When the current opposes the wave, the roll response decreases. When the current and wave come from the same direction, the roll response increases significantly, as the current speed increases. The mean drift forces and moment on the submerged body are more affected by current than those on the semi-immersed circular cylinder or on the ship-like section in the encounter frequency domain.

• Wind and Structures
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• v.22 no.2
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• pp.253-272
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• 2016

The paper concerns with the method and results of wind tunnel investigations of the Strouhal number (St) of a stationary iced cable model of cable-supported bridges with respect to different angles of wind attack. The investigations were conducted in the Climatic Wind Tunnel Laboratory of the Czech Academy of Sciences in $Tel{\check{c}}$. The methodology leading to the experimental icing of the inclined cable model was prepared in a climatic section of the laboratory. The shape of the ice on the cable was registered by a photogrammetry method. A section of an iced cable model with a smaller scale was reproduced with a 3D printing procedure for subsequent aerodynamic investigations. The St values were determined within the range of the Reynolds number (Re) between $2.4{\cdot}10^4$ and $16.5{\cdot}10^4$, based on the dominant vortex shedding frequencies measured in the wake of the model. The model was oriented at three principal angles of wind attack for each of selected Re values. The flow regimes were distinguished for each model configuration. In order to recognize the tunnel blockage effect the St of a circular smooth cylinder was also tested. Good agreement with the reported values in the subcritical Re range of a circular cylinder was obtained. The knowledge of the flow regimes of the airflow around an iced cable and the associated St values could constitute a basis to formulate a mathematical description of the vortex-induced force acting on the iced cable of a cable-supported bridge and could allow predicting the cable response due to the vortex excitation phenomenon.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.57-62
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• 2013

Because there is no suspension and differential devices at cart body, the deformation of the frame happened during kart driving affects the driving performance caused by the elastic deformation and the fatigue life of kart frame resulted from the permanent deformation. The dynamic behavior of kart caused by the torsional deformation during circular driving is the important factor of these two kinds of deformations. In order to analyze the dynamic behavior of kart at this curved section, GPS is used to trace the track of kart and the torsional stress at kart-frame has been measured with real time. The mechanical properties of kart-frames for leisure and racing are investigated through material property analysis and tensile test. Torsional stress concentration and frame distortion are investigated through stress analysis on frame on the basis of study result. The real karts for leisure and racing kart are also tested in each driving condition by using the driving analysis equipment. The driving behavior of kart at the curved section are investigated through this test. As the phenomenon of load movement due to centrifugal force at car is happened during circular driving, the torsional stress occurs at cart steel frame.