• Composites Research
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• v.13 no.1
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• pp.69-77
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• 2000

This paper presents a modified arc-length method for the nonlinear finite element analysis of a structure which is loaded in incremental and fixed forces, simultaneously. The main idea of the method is to separate the displacement term by the constant force from that by the incremental force. Presented method is applied to the nonlinear analysis of isotropic shell structures separately loaded by lateral pressure or compression, and shows the excellent agreement with previous results. As an illustrative example of the applicability of the present algorithm, a parametric study is performed on the nonlinear buckling analysis of composite cylindrical panels under the combined load of the incremented compression and the constant lateral pressure.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.30.1-30.1
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• 2015

Radio relics are diffuse radio sources found in the outskirts of galaxy clusters and they are thought to trace synchrotron-emitting relativistic electrons accelerated at shocks. We explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301 impinges on a magnetized cloud containing fossil relativistic electrons. This model is expected to explain some observed characteristics of giant radio relics such as the relative rareness, uniform surface brightness along the length of thin arc-like radio structure, and spectral curvature in the integrated radio spectrum. We find that the observed surface brightness profile of the Sausage relic can be explained reasonably well by shocks with speed $u_s{\sim}3{\times}10^3km/s$ and sonic Mach number $M_s{\sim}3$. These shocks also produce curved radio spectra that steepen gradually over $(0.1-10){\nu}_{br}$ with a break frequency ${\nu}_{br}{\sim}1GHz$, if the duration of electron acceleration is ~60-80 Myr. However, the abrupt increase in the spectral index above ~1.5 GHz observed in the Sausage relic seems to indicate that additional physical processes, other than radiative losses, operate for electrons with the Lorentz factor, ${\gamma}_e$ > $10^4$.

• Journal of the Korea Institute of Building Construction
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• v.8 no.6
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• pp.161-166
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• 2008

This study is focused on the welding performance of automatic gas pressure welding machine adapted to korean construction site by external appearance investigation. As gas pressure welding is more economical and has good performances compared with other steel bar jointing methods, as arc welding and mechanical joint etc, in Japan, the gas pressure welding is one of the typical connection of steel reinforcement when connecting the D29 and thicker steel bars, But in Korea, gas pressure welding joint method is not widely used caused by the shortage of skilled workers. so to activate the gas pressure welding in Korea, the automatic gas pressure welding machine is developed. In this study, the welding performances of gas pressure welding joint samples using korean automatic gas pressure welding machine are measured by external appearance investigation - blown diameters, blown length, welding face disagreement, central axis eccentric ratio, bending, sag and crack. The results of welding performances on the gas pressure welding joint samples show that samples are satisfied with the standard value regulated in KS D 0244 and JIS Z 3120.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.127-135
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• 1984

This paper considers the problem of optimum shaping of steel arches subjected to general loading. The weight of arches is considered as the objective function and the appropriate combinations of section forces, material volume, arc length, and closed section area of arches are considered as the stress constraints. The shape optimization problems are formulated in terms of the design variables of sectional areas of each element. First the cost sensitivity of the design is investigated. Then the investigation comprises the search for the optimum arch form as well as the optimum area distribution along the arch. Two spaces of shape optimization algorithm will be treated, the first space corresponding to the section optimization by the Modified Newton Raphson Method, and the second space to the coordinate optimization by the Powell Method. The optimization algorithm is evaluated and the optimum span-rise ratios for the given arches are evaluated.

• Composites Research
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• v.14 no.4
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• pp.27-34
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• 2001

The finite element method based on the total Lagrangian description of the motion and the Hellinger-Reissner principle with independent strain is applied to investigate the nonlinear behavior and vibration characteristics for patched reinforced laminated spherical panels. The patched elements are formulated using variable thickness at arbitrary point on the reference plane. The cylindrical arc-length method is adopted to obtain a nonlinear solution. The post-buckled vibration is assumed to be small amplitude. The effect of patch in the spherical shell Panel is investigated on the nonlinear response and the fundamental vibration characteristics. The present results show that the load-carrying capability can be improved by reinforcing patch. The fundamental frequency of patched panel is lower than that of equivalent shell panel. However, the fundamental frequency of patched panel does not decrease greatly due to the increase of nonlinear geometrical stiffness under loading.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.1
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• pp.83-86
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• 2014

Many have been performed to decrease the thickness of polyethylene terephthalate (PET) bottles to reduce the manufacturing cost. However, it is difficult to guarantee the mechanical strength under top-loading after decreasing the thickness. This paper investigates the large deformation characteristics of a PET bottle under a compressive load using experimental and finite element analysis (FEA) data. A round 1.65-L bottle is analyzed under a compressive velocity of 5 mm/min with a maximum load of 9,800 N in experiments. The arc length method is used in a nonlinear FEA to understand the buckling phenomenon of the PET bottle. From the analyzed results, a recommendation is made to restrict the top loading to less than 1,208 N, because the first buckling phenomenon occurred at a load of 1,208 N.

• Journal of the Ergonomics Society of Korea
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• v.21 no.3
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• pp.59-79
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• 2002

The purposes of the study were to present the optimum slacks pattern for elementary school girls and to compare and evaluate wearing ease of the slacks. 3D scans using the Cyberware PS motion platform were carried out for 3 subjects who have different body type. The automatic drafting method was programmed by AutoLISP in CAD. Wearing tests using 3D Scanner was done for evaluation of fitness of slacks. Regression analysis, analysis of variance and post-hoc test were performed for statistical analysis of the data by SPSS program. The procedure and results were as follows: The slacks construction components for pattern drafting were derived from 10 horizontal section maps obtained from 3D scans. The automatic drafting was based on the measurements of slacks construction components and the curve of crotch line. The crotch line was drafted using of the arc function in AutoCAD. The total crotch length was calculated using the multiple regression equation. Wearing test represented that the slacks pattern developed to accomodate individual body measurements was estimated more highly than existing patterns.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.9
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• pp.1571-1576
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• 2016

A Tesla coil is an electrical resonant transformer circuit invented by Nikola Tesla in 1891. It is used to produce high-voltage, low-current, high frequency alternating-current electricity. Tesla coil can generate a long streamer with several million volts of electricity as a high voltage device. It is basically consists of a voltage transformer, high voltage capacitor, spark gap, primary coil, secondary coil and toroid. It is difficult to appear in the output size of the streamer is controlled by the spark gap. The general decision method of the length of streamer is to display the electric output in accordance with the design specifications in initial development plan. Design specifications and the electric output is determined by the application of facilities. In this paper the spark gap is replaced with periodic switching semiconductor device to control output voltage easily in order to apply overvoltage protective circuit due to a secondary coil and a performance test. In these days, their main use is for entertainment and educational displays of the museum, although small coils are still used as leak detectors for high vacuum systems.

• Steel and Composite Structures
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• v.28 no.4
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• pp.427-438
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• 2018

Static stability is a decisive factor in the design of domes. Stability-related external factors, such as load and supports, are incorporated into structural vulnerability theory by the definition of a relative rate of joint well-formedness ($r_r$). Hence, the instability mechanism of domes can be revealed. To improve stability, an optimization model against instability, which takes the maximization of the lowest $r_r$ ($r_{r,min}$) as the objective and the discrete member sections as the variables, is established with constraints on the design requirements and steel consumption. Optimizations are performed on two real-life Kiewitt-6 model domes with a span of 23.4 m and rise of 11.7 m, which are initially constructed for shaking table collapse test. Well-formedness analyses and stability calculation (via arc-length method) of the models throughout the optimization history demonstrate that this proposed method can effectively enhance $r_{r,min}$ and optimize the static stability of shell-like structures. Additionally, seismic performance of the optimum models subjected to the same earthquake as in the shaking table test is checked. The supplemental simulations prove that the optimum models are superior to the original models under earthquake load as well.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.10
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• pp.59-66
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• 2011

In electric power system, the circuit breaker is not operated when the higher voltage then the rated TRV(transient Recovery Voltage) appeared in the circuit breaking, The TRV of a circuit breaker means the characteristics of reignition by the arc between two poles. and is decided by the value of connecting Impedance. In this paper we of carried out many kinds of experiments varying the types of bus, the types of installation, the length of installation between 22.9 [kV] level circuit breaker and MTR in general 154/22.9[kV] system, We also simulated the characteristics of TRV using EMTP-RV program. The suitability of TRV in assessed by Uc, RRRV(Rate of Rise of Recovery Voltage) which are defined by the international guide, IEC62271-100. The values of RRRV gained from the cable-made bus are 590[%] lesser than those from the NSPB-made bus respectively. So the triangled type is more rational in the aspect of TRV.