• Earthquakes and Structures
• /
• v.8 no.3
• /
• pp.573-589
• /
• 2015

In order to investigate the seismic behavior of highway bridges under near-fault earthquakes, a parametric study was conducted for different regular and irregular bridges. To this end, an existing regular viaduct Highway Bridge was used as a reference model and five irregular samples were generated by varying span length and pier height. The seismic response of the six highway bridges was evaluated by three dimensional non-linear response history analysis using an ensemble of far-fault and scenario-based near-fault records. In this regard, drift ratio, input and dissipated energy as well as damage index of bridges were compared under far- and near-fault motions. The results indicate that the drift ratio under near-fault motions, on the average, is 100% and 30% more than far-fault motions at DBE and MCE levels, respectively. The energy and damage index results demonstrate a dissipation of lower energy in piers and a significant increase of collapse risk, especially for irregular highway bridges, under near-fault ground motions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.12
• /
• pp.1266-1273
• /
• 1991

Attenuation losses and repeater spans of single-mode optical fibers installed in the long hual optical transmission line were measured and analyzed. The average loss including splicing points was appeared to be 0.55 0.05dB/km and 0.59 0.01dB/km at 1300nm and 1550nm, respectively, and showed lager value at 1550nm window, The cause of loss increase at 1550nm range from the OTDR measurement was due to the inappropriate treatment of extra length of fiber at the splicing points. And average repeater span of domestic long haul line was 24 7km and 90% of total sampled repeater spans was within 31 km.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.1
• /
• pp.72-86
• /
• 1998

This paper introduces a simple yet accurate method to predict burst rate and durence expected in a meteor burst communication path in question by comparing its path specifications to those of an exiting path. In this article, the authors analyze the method to derive the burst rate and duration by comparing span distance, frequency, antenna gain, transmitting power and thre- shold level to those of a existing path selected for the reference. the authors further report the result of experiments made for two difference paths; 750 km path and 1,200 km path to Hamamatu Japan and Hatinohe Japan from Kyongsan korea respectively. The occuring rate and average length of the bursts measured on the experiment paths show fairly good agreement with the analysis.

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.79-82
• /
• 2008

The elastic critical moment of I-beams subjected to moment is directly affected by the following factors; loading type; loading position with respect to the mid-height of the cross section; end restraint conditions. Most design specifications usually provide buckling solutions derived for uniform moment loading condition and account for variable moment along the unbraced length with a moment gradient correction factor applied to these solutions. In order for the method in the SSRC Guide to be applicable for singly symmetric I-beams, improved moment gradient correction factors were proposed in this study. Finite element buckling analyses of singly symmetric I-beams subjected to transverse loading applied at different heights with respect to the mid-height of the cross section were conducted. Transverse loads consisting of a mid-span point load and a uniformly distributed load were considered in the investigation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.6
• /
• pp.975-980
• /
• 2017

Overhead catenary system of electric railway has overlap sections which devide and tighten trolley wire supplying electric power to train, where current collection performances may become worse according to railway speed-up. Current collection tests conducted at 400 km/h test-bed section of Honam high-speed railway show that balanced line arrangement at overlap section is needed to secure current collection without arc generation between trolley wire and train current collection device. This paper proposes a design procedure of the overlap section to allow for tension increase and uplift of the trolley wires according to railway speed-up. By applying the proposed procedure to the overhead catenary system of Honam high-speed railway, it is suggested that the minimum span length should be 33.2 m for railway speed-up to 350 km/h and 43.7 m for speed-up to 400 km/h.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.7
• /
• pp.2702-2707
• /
• 2010

The load distribution factor (LDF) values of new composite I-beam panel bridges that were subjected to dead load were investigated using three-dimensional finite element analyses with the computer program ABAQUS(2007). This study considered some design parameters such as the slab thickness, the steel-plate thickness, and the span length for design of new composite bridges. The distribution values that were obtained from these analyses were compared with those from the AASHTO Standard, AASHTO LRFD, and the equations presented by Tarhini and Frederick, and Back and Shin. For the simple application of the design, bridge engineers can use the LDF of 0.67 for the exterior girder and of 0.340 for the interior girder.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.4 no.2
• /
• pp.103-111
• /
• 2000

The objectives of the study are to know the strain distribution and modal dynamic behaviour of steel bridge girders by actual traffic load. The live load effect depends on many parameters including the span length, gross vehicle weight, axle weight, axle configuration so on. For the estimation of static and dynamic characteristic, strain data caused by moving loads and traffic characteristics of passing vehicle under actual traffic load have measured using Bridge Weigh in Motion. To confirm the reliability of BWIM system, strain data measured using the $120{\Omega}$ strain gauge under the same condition. It is considered that the data acquired from BWIM system have reliability through the analysis and comparison between stress measured by strain data from BWIM and computed by FEM. Additionally according to the measured strain data of up-line and down-line on the highway, the up-line bridge grows more faster than the down-line bridge and girder 4 and 5 carry more load when vehicles pass the inner line and girder 2 and 3 does when vehicles pass the outer line as this case(the bridge composed with 5 girders).

• Journal of the Earthquake Engineering Society of Korea
• /
• v.19 no.4
• /
• pp.161-171
• /
• 2015

A series of tests was conducted for full-scale single-pylon asymmetric cable-stayed bridges using a system of multiple shaking tables. The 2-span bridge length was 28 m, and the pylon height was 10.2 m. 4 different base conditions were considered: the fixed condition, RB (rubber bearings), LRB (lead rubber bearings), and HDRB (high damping rubber bearings). Based on investigation of the seismic response, the accelerations and displacements in the axial direction of the isolated bridge were increased compared to non-isolated case. However, the strain of the pylon was decreased, because the major mode of the structure was changed to translation for the axial direction due to the dynamic mass. The response of the cable bridge could differ from the desired response according to the locations and characteristics of the seismic isolator. Therefore, caution is required in the design and prediction in regard to the location and behavior of the seismic isolator.

• Structural Engineering and Mechanics
• /
• v.50 no.5
• /
• pp.697-708
• /
• 2014

The intentional buckling design of micro-films has various potential applications in engineering. The buckling amplitude and critical strain of micro-films are the crucial parameters for the buckling design. In the reported studies, the film parameters were regarded as deterministic. However, the geometrical and physical parameters uncertainty of micro-films due to manufacturing becomes prominent and needs to be considered. In the present paper, the probabilistic nonlinear buckling analysis of micro-films with uncertain parameters is proposed for design accuracy and reliability. The nonlinear differential equation and its asymptotic solution for the buckling micro-film with nominal parameters are firstly established. The mean values, standard deviations and variation coefficients of the buckling amplitude and critical strain are calculated by using the probability densities of uncertain parameters such as the film span length, thickness, elastic modulus and compressive force, to reveal the effects of the film parameter uncertainty on the buckling deformation. The results obtained illustrate the probabilistic relation between buckling deformation and uncertain parameters, and are useful for accurate and reliable buckling design in terms of probability.

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.3
• /
• pp.31-37
• /
• 1994

When a lot of input data are not distributed uniformly n a chord-span direction or when the given shape is complicated, it is very difficult to obtain an inverse matrix which represents the smooth Bi-cubic B-spline surface of the initial shape. To overcome this problem, we suggest image Surface Expansion Method(ISE Method) which is suggested for vertex creation of B-spline curves and surfaces. Its basic concept, convergency and verification are shown. Also B-spline curves and Surfaces represented by ISE Method were compared with those represented by the existing method which is based on the inverse matrix method, the pseudoinverse matrix method and the chord length approximation method for vertex yielding. Ship Hull Forms which have Knuckle, Bulbous Bow, Transom and Stern frame were represented by the ISE Method.