• Journal of Korean Society of Steel Construction
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• v.23 no.6
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• pp.669-677
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• 2011

The multi-span suspension bridge generally has more than three towers and two main spans. To economically and effectively design a multi-span suspension bridge, the proper stiffness ratio of the center tower to the side tower must be determined. This study was conducted to propose a method of figuring out briefly the structural behavior of the towers in a multi-span suspension bridge. In the equivalent suspension bridge model, the main cable of the multi-span suspension bridge is idealized as an equivalent cable spring, and the external loads of horizontal and vertical forces that were calculated using the tensile forces of the main cable were applied on top of the towers. The equilibrium equations of the equivalent multi-span suspension bridge model were derived and the equations were solved via nonlinear analysis. To verify the proposed method, a sample four-span suspension bridge with a main span length of 3,000 m was analyzed using thefinite element method. The displacements and moment reactions of each tower in the proposed method were compared with the FEM analysis results. Consequently, the results of the analysis of the equivalent suspension bridge model tended to be consistent with the results of the FEM analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.55-65
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• 2006

This paper presents the closing analysis of a symmetric steel cable-stayed bridge erected by a free cantilever method. Two independent structural systems are formed before the closing procedure of a bridge is performed, and thus the compatibility conditions for vertical displacement and rotational angle are not satisfied at the closing section without the application of proper sectional forces. Since, however, it is usually impossible to apply sectional forces at the closing section, the compatibility conditions should be satisfied by proper external forces that can be actually applicable to a bridge. Unstrained lengths of selected cables and the pull-up force of a derrick crane are adjusted to satisfy nonlinear compatibility conditions, which are solved iteratively by the Newton-Raphson method. Cable members are modeled by the elastic catenary cable elements, and towers and main girders are discretized by linear 3-D frame elements. The sensitivities of displacement with respect to the unstrained lengths of selected cables and the pull-up force of the derrick crane are evaluated by the direct differentiation of the equilibrium equation. A Monte-Carlo simulation approach is proposed to estimate expected construction errors for a given confidence level. The proposed method is applied to the second Jindo Grand Bridge to demonstrate its validity and effectiveness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.47-59
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• 2013

Ultimate load factors of PPWS(Prefabricated Parallel Wire Strand) sockets in main cables of suspension bridges are studied with respect to the tapered angles of the inner surface of sockets. After briefly reviewing the current design method, 15 numbers of finite element models of sockets are prepared by varying the number of wires in a strand and the tapered angles. The finite element models are updated by comparing experimental and numerical results, so that the models can reflect the real behavior of sockets. The stress distributions at the first yielding and ultimate states are analyzed by performing the incremental load analysis using ABAQUS. It is concluded that the optimized tapered angle of sockets should be determined at the specific angle between the results of verification equations of the required bonding length and stress resistance length.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.49-62
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• 1994

An analysis method for the time-dependent nonlinear analysis of segmentally erected planar prestressed concrete cable-stayed bridges was described. To account for the time-dependent effects, load history, creep, shrinkage. aging of concrete and relaxation of prestress were considered. Changes in boundary conditions and loads, installing and removing frame elements, stressing, restressing and removing cables and prestressing tendons were incorporated for modeling segmental erection operations. One typical example on segmentally erected prestressed concrete cable-stayed bridge was presented to illustrate the analysis method. Results of this example show that it is important to follow the development of stresses and deformations at all stages of construction to predict the true response of the bridge through its various load history.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.426-427
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• 2008

전력의 안정적 공급, 공급 신뢰도 향상 및 도심지 인구밀집 지역의 전력공급 및 미화 등의 축면에서 송전분야에서의 지중화는 필수적이며 지속적으로 증가추세에 있다. 그러나 제한적인 지중공간을 활용함에 따른 여러 문제가 발생하고 있다. 지중선로 고장상황으로 1선 지락, 2선지락, 선간단락, 3상단락 등의 사고가 있으며 이러한 고장상황에서 발생하는 고장전류에 의한 열거동은 지중선로에 악영향을 준다. 그러므로 각 고장상황에 따른 지중선로의 영향에 대한 세부적인 검토가 필요하다. 본 논문에서는 각 고장상황에 따른 검토조건으로 1회선과 2회 선일 경우와 상배열이 정삼각배열, 수평/수직배열, 직각배열일 경우를 선정하여 지중선로에 미치는 영향을 EMTP, IDEARS, MARC를 활용하여 분석하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.602-607
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• 2009

Most of explorer robot in past has the fixed magnitude and communicate with wire communication method. In case of various range of pipe's width and various angle in pipe inter structure, the exploring work is very difficult. Thus, in this paper, we design as dealing with spring tension with pushing out pipe exterior, and applied RF communication. We can accept good performance both structure change and improvement of ability, monitor and collect the defaults data in pipe inter structure. Newly designed and developed pipe explorer robot is very advantageous to carrying and driving as being small and law weight.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.9-18
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• 2006

This paper presents schematically the monitoring system installed in Yongjong Bridge, a self-anchored suspension bridge located in the expressway linking Seoul and Incheon International Airport. Automatic measurement of instrumented civil engineering structures is now widely applied for behavior monitoring during construction in field as well as long-term monitoring for lifetime assessment of bridge structures. A representative example of results that can be acquired through structural health monitoring system is presented by means of data measured during a few years after the opening of the bridge. In order to effectively measure the tension force for hangers that have relatively short length or high tension force, a static tension measurement device has been explored. Newly equipped railway system on the existing bridge results in change of dead load, consequently dynamic characteristics have also been changed. This result can be detected by the monitoring system during and after railway construction.

• Journal of Digital Convergence
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• v.12 no.2
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• pp.307-314
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• 2014

Digital broadcasting areas are leading information technology and having been strengthen the competitiveness of industries. In this paper, we developed HSS(Home Stream Station) for recording and transmitting digital broadcasting on digital TV without additional devices, which is based on cable TV network at home. The HSS can record a broadcasting program selected by user while digital TV shows the other channel. User can watch the program stored on the HSS at any time and any digital TV in the home. LAN interface of the HSS was also developed for supplying high quality digital broadcasting-contents through home network using IP-STB(Set Top Box).

• The Journal of the Korea Contents Association
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• v.10 no.10
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• pp.111-119
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• 2010

This paper deals with the experiments of optokinetic differentiation within eye tracking test through the menu direction and cognitive degree of service menu title for watching digital media service. Researcher establish a research topic which verification of differentiations of eye tracking velocity when media user perceive the service menu title within vertical structure or horizontal structure. Experimentation was designed with two types of menu structure-vertical or horizontal-and these have each 9 cases of eye tracking tasks for experimentee. Researcher arrives at a conclusion through as stated above experiment that cases of vertical menu structure is more effective method with linear channel service menu, otherwise that cases of horizontal menu structure is more effective method with non linear channel service menu, like a video on demand service. The research results will be very helpful with actual media industry players when they planning the evolutionary direction of their menu layout.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.393-401
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• 2009

The flexural-stiffness formula of the wale for the innovative prestressed support (IPS) system was precisely derived, and the equivalent beam stiffness was introduced for application in the actual design of the IPS wale. The cable tension forces of the IPS wale were calculated in both cases, and the axial-deformation effects were included and ignored, respectively. The central displacements of the 1-post, 2-post, 3-post, and 4-post IPS wales were calculated based on the principle of virtual work. The effects of the IPS wale length and cable inclination angle were also investigated using the derived central displacements. The simplified equivalent flexural stiffness of the IPS wale is presented herein for design purposes, and the validity of the proposed design formula was verified through its comparison with the FE and analysis solutions.