• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.55-66
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• 1991

Presented is a study on the realistic determination of design loads and design criteria for bridge structures. The current bridge design code does not consider realistically the uncertainties inherent in loads and resistances and thus the level of safety varies greatly among the bridge spans. The resonable bridge design loads and design criteria which exhibit uniform reliability among various bridge spans are therefore derived in the present paper. The proposed design loads are determined from the analysis of numerous data obtained from actual traffic survey and the design criteria are based on the advanced concept of load and resistance factor format. The live load factors take into account resonably the effects of traffic volume increase. The proposed design loads and design criteria show uniform safety level for various bridge spans and reasonably consider the effects of traffic volume increase. The present study provides useful and valuable data for new version of our bridge design code.

• Fire Science and Engineering
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• v.27 no.1
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• pp.52-59
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• 2013

In this study, tests were conducted to establish a fire engine of relay waterproof and utilization in order to maintain the pressure in a situation that require high-pressure water-resistant such as a high-rise building fire, etc. As a result of test on the change of a relay waterproof pressure, the measurement result with the hydrant intake of a fire engine opened has reduced approximately 20 % compared to the measurement result with the hydrant intake closed. Similar efficiency showed in the test result that change the pressure of 2 fire engines respectively to use them more efficiently at a fire fighting activity site. A fire engine operation and utilization is proposed based on this study result in order to cope effectively with a fire site requiring high-pressure stream in a high-rise building fire, etc. by using a fire engine held at present because there is no fire pump with high-pressure stream ability arranged at the fire station and there is no regulation on high-pressure fire-fighting pumps in a type approval and verification technology criterion for a fire engine.

• Journal of Korean Society of Steel Construction
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• v.13 no.3
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• pp.313-325
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• 2001

Tubular bridge rail was developed to restrain and redirect a 14ton van-type truck. The developed bridge rail permits better visibility than concrete safety-shape bridge rail, and it has better structural adequacy than the existing steel and aluminum bridge rails in Korea. The new bridge rail consists of a tubular thrie beam(TTB) rail and a steel guard rail, which are connected to composite posts. The TTB shape provides both better containment of diverse bumper heights and more tight fit between the ends of bridge rail and roadside guardrails than the existing bridge rail sections currently used in Korea. Making composite post by filling concrete inside the steel pipe of the same size as are used for the roadside guardrail post was found to be more efficient in increasing the stiffness and ultimate strength than simply increasing the size of the steel pipe. The system was crash-tested for the impact condition of 14ton-80km/h-$15^{\circ}$, and it satisfied all evaluation criteria set forth in NCHRP Report 350 for a Test Level 4 safety appurtenance. Acceptable performances were obtained in computer simulations for the impact condition of S2.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.4
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• pp.11-21
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• 1982

The dynamic strain-time(${\varepsilon}$-t) curves of the fatal members in three existing steel railway bridges was measured during the selected trains was passing, and was regulated statistically. By the results of these the equivalent fatigue damages of the selected members was calculated in comparison with the allowable stresses, and was examined. From these the base available in evaluating the stability and the lifeproof of the steel railway bridge was obtained. In addition to this, the following several properties which could be used availably in designing the steel railway bridges. It was conformed that the fatigue damages was different each other even in the same members, if the unit weight of the trains was same but the weights and the dispositions of the wheels of the trains was different each other. It was indicated that the fatigue damages was larger in the members which had the defects in components of the materials, the flaws being made during producing and constructing, and the corrosions, etc. It was considered that more a vailable data could be obtained, if the same studies were continued under the spans and the types of the bridges being changed continuously.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1174-1187
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• 2007

Monorail System has many advantages compared with other Urban Lightweight Transit Systems, such as the friendliness of the vehicle's appearance, slenderness of the bridge structures, it's low construction cost and short construction period. So, lots of city governments have reviewed or proposed the Monorail System as the attractive alternative system. And recently, Daegu Metropolitan City Government have chosen the Monorail System for the Urban Railroad Line 3. According to these trends on Urban Lightweight Transit Systems, this paper has introduced the outline of the planning and design of Monorail Bridges. At first, trends of overseas Monorail Bridges have been reviewed and the principal design criteria adopted in the basic design of the Urban Railroad Line 3 for Daegu have been introduced. And next, the methods of planning, design, fabrication of the guideway beams which are made of PSC Beam or Steel Beam have been explained. We hope this paper be helpful for the Engineers who are interested in the Monorail Bridges.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.97-104
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• 2004

As a device that returns surplus energy, regenerated from trains to d.c. source, to a.c. system and reuses it, the thyristor Inverter has been widely used. Because the conventional thyristor inverter is a unidirectional phase-controlled device, it Is Impossible to control the power factor of its output. Moreover, harmonics emission is high and it needs to take a additional filter. In this paper, to solve the problems stated above, the inverter, which can control real and reactive power by adopting IGBT modules as switching elements and being controlled by means of space vector PWM, is developed. Considering high economical efficiency and reliability in order to apply to the system for commercial use, the developed inverter is equipped with fully digital control system and low pass filter, and reduces harmonics and has compact size. The detail description about the developed inverter is stated in various respects: design criteria, technical description, power circuits, control techniques, the developed system, test results, etc.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.113-123
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• 2011

LCC analysis is a method that coordinates with function evaluation for value improvement, rather than a separate one for cost evaluation. Although its accuracy is rising, materials and structural types developed or applied relatively recently have yet to obtain a sufficient maintenance profile DB, inducing reliability to reduce from difficulties in estimating maintenance records. Based on the above mentioned background, this paper presents the LCC methodology of coordinating functional intensification matters with cost for analysis on alternatives with difficulties in setting maintenance profile. Recently, steel plate bridge deck pavements are faced with problems such as plastic deformation due to the increase in heavy vehicles and traffic, promoting the development of a new compound pavement. This paper execute LCC analysis by mentioning case studies of SMA, Guss and PSMA pavements to include performance scale compared between alternatives as relative evaluation coefficients into the maintenance profile.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.172-178
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• 2012

Superimposition of vertical and transition curves is not allowed for all types of tracks in Korean regulation of railway construction. However, this criterion has been established on the basis of difficulty of maintenance of the ballasted track. Comparing with the ballasted track, the concrete slab track has the advantage of maintenance and structural, which allows the superimposition of vertical and transition curves when it satisfies the criteria of running safety and riding comfort. In this study, running safety, ride comforts and track acting forces were analyzed and compared by numerical analysis using VAMPIRE program when the vertical and transition curves are superimposed for the ballasted track as well as the concrete slab track. From the analysis results, it was found that running safety, riding comforts and track acting forces in case of superimposition of vertical and transition curves for the both tracks meet all of the criteria. Therefore, although superimposition of vertical and transition curves for the ballasted track is not allowed because of a lot of maintenance works, it can be applied to the concrete slab track considering the advantage of maintenance and structural safety.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.271-280
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• 2011

This study intends to analytically evaluate the vibration serviceability of the bridges for each long-span type having the same span length and road width using the Meister vibration sensation curve. With MIDAS, a structural analysis program, bridges were modeled using the girders as the frame element and slabs as the plate element. The transient analysis was performed using the moving loads of the design vehicles. This study presents the analytical process of reviewing the vibration serviceability during the design of long-span bridges. It involves the comparison of the vibration serviceability of different bridge types by applying the lagging-behind and acceleration amplitude from transient analysis to Meister curve. The result confirms that the process is appropriate.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.183-193
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• 2008

The reliability analysis of simply-supported and continuous composite plate girder and box girder bridges under flexure was performed to provide a basic data for the development of LRFD c ode. The bridges were designed based on LRFD specification with newly proposed design live load which was developed by analyzing traffic statistics from highways and local roads. A performance function for flexural failure was expressed as a function of the flexural resistance of composite section and the design moments due to permanent load and live load. For the flexural resistance, the statistical parameters obtained by analyzing over 16,000 domestic structural steel samples were used. Several different values of bias factors for the live load moment from 1.0 to 1.2 were used. Due to the lack of available domestic measured data on the moment by permanent loads, the same statistical properties used in the calibration of ASHTO-LRFD were ap plied. The reliability indices for the composite girder bridges with various span lengths, different live load factors, and bias fact or for the live load were obtained by applying the Rackwitz-Fiessler technique.