• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.145-153
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• 2016

Cable TV with largest subscription base in pay TV market has difficulty in managing the task of digital switch over. This study analyzed the factors in delay of cable TV switch over and examined the impact of pay TV market structure and competition. The delaying factors turned out to be the lack of incentives and resources of cable TV operators, insufficient policy measures and acceptance tolerance issues of subscribers. Since cable TV operators with monopolistic status in pay TV market had continuous profit from analog service, they were not responsive to digital switch over which requires additional investment. Policy measures including support for the low income household and mandatory cut-off point for stopping analog broadcasting. Subscriber's willingness to accept digital broadcasting in terms of price sensitivity and preference for convenient operation also played a role. Introduction of IPTV in pay TV market influenced the speed of digital switch over of cable TV operators. MSOs with economies of scale showed higher digital switch over rate than independent SO.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.9
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• pp.609-616
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• 2022

The performance of antenna reflectors crucially depends on the faceting error of the surface. The force density method (FDM) has been widely used for the form-finding analysis of the cable nets of reflectors. However, after performing form-finding of some cable nets, the effective reflective area will decrease. In addition, nonlinear deformations of the cable can not be achieved by using the FDM. Thus, an effective form-find methodology is proposed in this research. The whole parts of the cable networks are described by the absolute nodal coordinate formulation. The form-finding analysis of the reflector with standard configuration is performed to validate the proposed methodology. The influence of boundary condition changes on the configuration accuracy of the cable net is investigated.

• Computational Structural Engineering
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• v.4 no.1
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• pp.42-43
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• 1991

균열성암반의 모형화 기술은 계속적으로 보완발전되어 UDEC이 개발되었으며, 현재 UDEC의 최신판은 블록 내부를 다시 유한차분요소로 분할하여 블록의 소성거동(Mohr-Coulomb Model) 및 쪼개짐을 고려할 수 있고, 절리면에서의 유체흐름 및 유압의 발생, 그리고 열응력 해석 등 평면변형 문제의 정적해석과 지진 및 폭발하중을 고려한 동적해석이 가능하다. UDEC은 전처리 기능이 뛰어나 최소한의 입력데이타로써 전체 모형의 데이타를 자동생성시키며 절리면의 통계학적 자동생성 및 터널형상의 자동생성도 가능하다. UDEC은 실용적인 보강요소를 구비하여 Rock Bolt 뿐만 아니라 그라우트를 고려한 Cable Bolt를 모형화할 수 있으며 국부적인(Key Block)보강으로써 불연속체 전체의 안정을 검토할 수 있다.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.91-96
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• 2004

Overloading of electrical equipment results in excessive currents. As the heat developed in the cables is proportional to square of the current, they get overheated. The insulation on cables is generally made of materials which are damaged easily by excessive temperature. They may therefore lose their insulating properties and lead to short circuits. Since many insulating materials are combustible, they may even catch fire if the temperature rises to their ignition temperature. In this paper, we have simulated the thermal analysis for cable according to the value of current in a overload and a short with the cable of the L's company product(600 V, VV : Four Core) using the electro-thermal finite element method(Flux2D).

• Journal of Industrial Technology
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• v.27 no.A
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• pp.47-53
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• 2007

A theoretical model based on Rayleigh-Ritz method is proposed to predict the resonance frequency of a W/T(Wind Turbine) tower structure supported by guy cables. In order to verify the validity of the theoretical model, a reduced W/T tower system is manufactured and tested. Frequency response and mode data are determined by modal testing and finite element analysis is performed to calculate the natural frequency of the tower model. Numerical and experimental results are compared with those by the theoretical analysis. Parametric study by the theoretical model shows how the cable tension and cable elasticity influence the resonance frequency of the W/T tower structure. Finally, vibration response under various rotating speed is investigated to examine the possibility of severe resonance.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.365-372
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• 2003

In this study, the program which determine the initial cable tension force by tile initial shape analysis for cable stayed bridge is developed. Also, DSFEMP(Dynamic Stochastic Finite Element Analysis Program) is developed to consider the variance of random variables at each step of dynamic response analysis, not use existing methods that apply to the theory of reliability at the final step of structural analysis. In addition, the output from the developed program was compared with the results from DMCSP(Direct Monte Carlo Simulation Program) to prove its validity.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.4
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• pp.403-415
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• 2014

Recently, the temperature rise in the summer due to climate change, power usage is increasing rapidly. As a result, power generation facilities have been newly completed and the need for ultra-high-voltage transmission line for power transmission of electricity to the urban area has increased. The mechanized tunnelling method using a shield TBM have an advantage that it can minimize vibrations transmitted to the ground and ground subsidence as compared with the conventional tunnelling method. Despite the popularity of shield TBM for cable tunnel construction, study on the mechanical behavior of cable tunnel driven by shield TBM is insufficient. Thus, in this study, the effect of fractured zone ahead of tunnel face on the mechanical behavior of the shield TBM cable tunnel is investigated. In addition, it is intended to compare the behavior characteristics of the fractured zone with continuous model and applying the interface elements. Tunnelling with shield TBM is simulated using 3D FEM. According to the change of the direction and magnitude of the fractured zone, Sectional forces such as axial force, shear force and bending moment are monitored and vertical displacement at the ground surface is measured. Based on the stability analysis with the results obtained from the numerical analysis, it is possible to predict fractured zone ahead of the shield TBM and ensure the stability of the tunnel structure.

• Journal of Korean Society of Steel Construction
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• v.16 no.3 s.70
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• pp.355-363
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• 2004

In order to obtain the effective length factor of beam-column members of plane frames, this paper extensively used an alignment chart approach, based on the nomograph given in LRFD-AISC specification commentaries. However, it should be noted that various simplifications and assumptions were introduced in constructing the alignment chart. To overcome the practical limitations of the alignment chart, this paper proposes a simple but accurate procedure that determined the effective buckling length for stability design of main members of cable-supported bridges. This method requires the full system buckling analysis. The numerical examples showing the suitability of the present scheme are discussed and some conclusions are drawn.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.947-954
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• 2016

A simplified analysis method is first proposed in order to determine an optimized initial shape of cable-stayed bridges including all unstrained element lengths without using complicated nonlinear FE analysis. The unstrained-length based FE method is then presented using the unstrained lengths by the simplified analysis. To demonstrate validity and accuracy of the proposed method, Incheon bridge model having the fabrication camber is constructed and initial shaping analysis is performed using the presented method and commercial finite element analysis program, MIDAS. Resultantly it is shown that the initial solutions by the proposed algorithm are well optimized and in good agreement with those by MIDAS except for axial displacements of the main member.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1069-1076
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• 2007

DOCSIS 3.0 protocol are proposed to support high-speed cable network DOCSIS 3.0 MAC protocol regulates CM and CMTS channel transfer times through MAP message. So MAP Inter-arrival time is primary factor of network performance. However, standards does not include the details of MAP Inter-arrival Time affecting the performance of MAC protocols for DOCSIS 3.0. In this paper, we evaluated the performance of DOCSIS 3.0 protocol follow in MAP Inter-arrival Time. Based on the evaluation results, we propose the optimal MAP Inter-arrival Time. We found that the protocol shows best performance when the MAP Inter-arrival Time is 0.05sec. The research results can apply to performance element which important for the construction of DOCSIS 3.0 base cable networks.