• Satellite Communications and Space Industry
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• v.14 no.1 s.29
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• pp.102-109
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• 2007

본 논문은 고속열차와 같은 고속 이동체에서 위성무선연동 전송기술을 이용하여 지상무선망과 동일한 수준의 인터넷 서비스를 제공하기 위한 이동형 위성 인터넷 접속기술에 관한 것이다. 이러한 서비스 제공을 위해서는 터널이나 역사(Railway Station)와 같은 N-LOS 환경에 대한 대처기술이 필요하며, LOS 환경에서도 철로상에 설치되어 있는 Electronic Power Post나 Power Bridge 등으로 인한 주기적이고 짧은 시간동안의 신호열화 현상이나 고속 이동에 따른 도플러 현상에 대한 극복기술이 필요하다. 이러한 기술들이 집약된 본 시스템을 소개한다.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1012-1017
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• 2008

In this study, We examine closely the capacity spectrum method which a kind of displacement-based method evaluated by displacement of structure as an alternative to the load-based analysis method. The displacement-based method can easily review the strength of structure, seismic performance, ductility. Seismic performance by using capacity spectrum method is divided into design response spectrum and capacity spectrum. We can diagram design response spectrum by deciding the design seismic factor depending on performance target, site classification, seismic level, return period as UBC-97. Capacity spectrum is a load-displacement curve obtained by Push-over analysis considering the geometric parameter and the material parameter. We execute the seismic performance evaluation by using the capacity spectrum method to reinforced concrete pier which has been seismic design. As a result, We confirmed that there is a yield point and a ultimate point close by design response spectrum of UBC-97.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.489-500
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• 1997

The number of railway bridges in Korea reaches to about 3,000. Among them, the ratio of steel bridges is about 47%. Most of the long span railway bridges take the truss type, its number is 15 in Korea. These bridges have more than 30 years service life, it is expected that the damages of cracks and corrosion is going. Therefore, the estimation of fatigue life with random stress is considered as significant subject in maintenance. In this paper, the random stress was measured in bridges and counted the stress cycles using the rainflow counting method So, the stress range frequencies and their equivalent stress are obtained and the amplification factor for the span length, bridge types and traveling speed is assessed by the dynamic testing. From the results, the stress range of the stringer and the lower chord is higher than the other members and the characteristics of the stress histogram is varied to the loading system and the amount of the passing through trains. And the impact effects are depended on the traveling speed as well as the span length.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.51-60
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• 2011

In this study, structural safety capacity analysis of the overpass railway bridge between Konkuk Univ. and Guui station railroad has been performed. The overpass is expected to have suffered durability reduction by deterioration. The weight reduction of the overpass has been implemented to prevent further durability reduction and to improve performance capacity. To reduce the weight, 3 procedures of replacing concrete soundproofing wall to light-weight soundproofing wall, replacing gravel ballast to concrete ballast, and reducing the weight of trough have been performed. The analysis of static/dynamic behaviors and improved capacity of the light-weighted overpass bridge has been performed. The structural safety verification of the improved structure has been implemented by using rating factors of load carrying capacity of PSC I girder. The results have shown that the deflection has been reduced by 2.6mm and tensile strength has been improved by 1.07MPa, which indicate that the structural capacity has effectively been improved. Also, the natural frequency has improved by approximately 30% where vibration reduction and dynamic behavior improvement have been achieved. Moreover, in the rating factor evaluation based on analysis and test results, an improvement from 1.82 to 1.93 has been observed. Therefore, weight reduction method for the overpass is effective considering overall results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.96-106
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• 2014

The increased vibration level of the railway bridge could make significant noise and, also, cause structural damages such as fatigue cracks. Related to these subjects, a spherical elastomeric bridge bearing, which is layered by hemispherical rubber and steel plates, was investigated in terms of its vibration performance. Several different shape factors could be considered by changing the curvature of hemispherical surface and size in rubber and steel plate thicknesses in the manufacturing stage. The performance of the spherical elastomeric bearing for the reduction in vibration was compared with that of the conventional bearing by performing vibration experiments on a scale-downed model. The rubber material characteristics and spherical shape are found to be important parameters in reducing the bridge vibration.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.515-525
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• 2016

Parameter analysis of a pretension girder bridge for urban maglev transit was performed to identify the main design parameters and their effect. Girder deflection at mid-span is the most important design criteria of urban maglev transit. Therefore, concrete compressive strength, girder height, girder length, and unbonded tendon length were selected as the design parameters that relate to girder deflection. In addition, tendon layout and unbonded tendon ratios were also considered as design parameters to control the top stress of the pretension girder section at the support. The analysis results show that both the girder height and length are dominant design parameters governing girder deflection, more important than compressive strength and unbounded tendon length. And, sensitivity analysis makes this study suggest design weight value. In terms of stress, a tendon layout that can satisfy the unbounded tendon rule requires an additional tendon or rebar at the upper section to control the tensile stress on top of the section. Therefore, to improve feasibility and constructability in the future, an enhanced unbonded tendon rule considering the load characteristics of the urban maglev system should be studied.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.549-559
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• 2005

A railway bridge with a double composite section is proposed to enhance the structural performance of existing two-girder bridges because the governing design parameter of railway bridges is the flexural stiffness. The concrete deck in negative moment regions is neglected in the design of continuous composite bridges assuming the concrete slab has no resistance to tension. Therefore, the flexural stiffness of the composite section in the negative moment region is reduced resulting in the increase of the depth of the steel section. In order to resolve this disadvantage, several methods are suggested and the double composite section is one of the excellent solutions for extending the span length and increasing the flexural stiffness. In this study, push-out tests on lying studs and mixed stud shear connection with lying and vertical studs were performed to investigate the behavior of the shear connection in the double composite section. Static strength of the shear connection was evaluated through the test results and numerical analyses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.30-41
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• 2017

Types of noise barrier installed for noise attenuation are largely divided into noise-absorbing format and noise-proofing format. In these days, installation of transparent noise barrier is general trend to solve problems that hinder sunshine and landscape. Some kinds of transparent boards are used to one of components in noise barriers, but in some cases, less transparency and worse pollution due to yellowing phenomena, and severe material deformation are to harm the urban aesthetics Therefore laminated-tempered glass board in that yellowing phenomena does not occur can be replaced as a transparent one to secure those shortcomings. In this paper, the structural safety against train induced vibration and the resistibility to wind load are analyzed for laminated-tempered glass system as a component of noise barrier installed on Metro railway elevated bridges. Also the appropriateness is evaluated through flexural bending performance test, compressive strength test, modulus of elasticity tests, and impact test for the system or the glass material itself. All of these processes are intended to present the deployment of logic to evaluate the adequacy for the system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.7
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• pp.817-822
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• 2014

Since the opening of the double-track railway for the Gyeongchun local electric train and the semi-high speed train ITX, floating population between Seoul and Chuncheon has rapidly increased. This is attributable to the competitiveness of the railway service in terms of punctuality and safety of operation, mass transportation and low fare. However, many passengers have expressed strong dissatisfaction and displeasure towards the interior noise and its high rate of increase, particularly in tunnel sections. In this study, the interior noise characteristics of Gyeongchun local electric train and ITX were analyzed and compared. Noise levels, frequency spectrum and sound quality indices were compared for the open land, tunnel and bridge. Finally, from the noise levels depending on the location in the vehicle compartment, the noise transmission path was determined and a basic strategy for reducing the interior noise was developed.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.521-527
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• 2010

The Paved Track is applied to reduce maintenance cost of conventional line. The Paved Track could be used in all types of lines including earthwork, bridge, tunnel and turnout sections. In case of earthwork section, the construction joint is the most critical factor to track durability. The construction joint does not affect to the track structure directly, but the gap due to discontinuity of slabs may affect to the long-term serviceability. To evaluate this problem, the accelerated track test has been performed on the construction joint and the middle part to of the real scale Paved Track. The purpose of this test is that evaluate the vulnerability of construction joint section comparing the trends of settlement and earth pressure under repeated loads of construction joint with those of the middle slab part.