• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.201-209
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• 2010

Generally, PSC girder bridge uses total gross cross section to resist applied loads unlike reinforced concrete member. Also, it is used as short and middle span (less than 30 m) bridges due to advantages such as ease of design and construction, reduction of cost, and convenience of maintenance. But, due to recent increased public interests for environmental friendly and appearance appealing bridges all over the world, the demands for longer span bridges have been continuously increasing. This trend is shown not only in ordinary long span bridge types such as cable supported bridges but also in PSC girder bridges. In order to meet the increasing demands for new type of long span bridges, PSC hollow box girder with H-type steel as compression reinforcements is developed for bridge with a single span of more than 50 m. The developed PSC girder applies compressive prestressing at H-type compression reinforcements using unbonded PS tendon. The purpose of compressive prestressing is to recover plastic displacement of PSC girder after long term service by releasing the prestressing. The static test composed of 4 different stages in 3-point bending test is performed to verify safety of the bridge. First stage loading is applied until tensile cracks form. Then in second stage, the load is removed and the girder is unloaded. In third stage, after removal of loading, recovery of remaining plastic deformation is verified as the compressive prestressing is removed at H-type reinforcements. Then, in fourth stage, loading is continued until the girder fails. The experimental results showed that the first crack occurs at 1,615 kN with a corresponding displacement of 187.0 mm. The introduction of the additional compressive stress in the lower part of the girder from the removal of unbonded compressive prestressing of the H-type steel showed a capacity improvement of about 60% (7.7 mm) recovery of the residual deformation (18.7 mm) that occurred from load increase. By using prestressed H-type steel as compression reinforcements in the upper part of cross section, repair and rehabilitation of PSC girders are relatively easy, and the cost of maintenance is expected to decrease.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.209-216
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• 1999

Prefabricated piles used for construction of highway bridges are most of steel pipe piles and few of prestressed concrete piles. Its installation and inspection are less controllable and have much uncertainty due to changes in subsoil and groundwater conditions. However, most of these piles have been controlled using outdated pile driving formula such as Hiley's formula which models just the energy conservation due to its simple applicability in the field. This formula results in overstriking or sometimes understocking due to buckling of pile head. Engineers cannot ensure by the formula whether pile is installed properly. To compensate the drawbacks of excising pile formula, parameters in Hiley's formula and 55 formula are reviewed. Final sets used in pile formula and PDA test results(E.O.I.D) are measured during pile driving along the depth. These measured results along the depth were compared with each other and with N values, so that relations between the each result could be inferred. Also the factor of safety which can be used for pile driving formula are suggested.

• Advances in concrete construction
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• v.10 no.1
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• pp.21-34
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• 2020

Precast deck joints have larger crack width than cast-in-place concrete decks. The initial crack typically occurs at the maximum moment but cracks on precast joints are significant and lead to failure of the deck. The present crack equation is applied to cast-in-place decks, and requires correction to calculate the crack width of precast deck joints. This research aims to study the crack width correction equation of precast decks by performing static tests using high strength and normal strength concrete. Based on experimental results, the bending strength of the structural connections of the current precast deck is satisfied. However it is not suitable to calculate and control the crack width of precast loop connections using the current design equation. A crack width calculation equation is proposed for crack control of precast deck loop joints. Also included in this paper are recommendations to improve the crack control of loop connections.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.548-553
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• 2008

Overloaded Vehicles are one of biggest of hazard in durability decrease of roads and bridges. Thus, regulation was put in force about overloaded vehicles to reserve this problem. However, existing system had many problems. For these reasons, this paper presents solutions of U-intelligent overload vehicles regulation system based on manless and wireless for fixing of problems of existing system and construction of ITS. With this in mind, we studied about composition method of system, applications of USN, design of system controller, WCDMA/ HSDPA, etc in this paper.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10c
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• pp.61-78
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• 2001

Various kind of fiber optic gauge sensors are available that can be bonded to civil engineering structures such as bridges, dams, tunnels and pipelines. A new fiber optic long gauge has significant advantages over other fiber optic sensors. These gauges can vary in length from less than 10 cm up to 30 m and provide the structural engineer with accurate measurements of displacement. These displacements can be converted to strains by dividing the measurement by the long gauge length. Using new optical technology, the long gauge instrument developed by FOX-TEK can choose max. 30 meters of gauge length so as to measure the very early stress/strain correlation curve. And this gauge length to be extended up to 100 meter in 2002.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1433-1437
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• 2005

Until now, strain gage technique and accelerometer for the diagnosis safety of constructions are used widely. However, the limits of these methods are revealed. But Electronic Speckle Pattern Interferometry(ESPI) that uses Pulse Laser is noncontact, whole-field, real-time measuring method also dull to disturbance and can achieve test result in a very short time. It has various strong point in spot application, swift establishment, and dynamic conduct analysis for the entire field of Laser illuminate. This author analyzed vibration characteristic of using the Pulse ESPI System, the diagnosis safety of bridges, to simplify the analysis of the dynamic conduct of a large construction.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.433-438
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• 2001

In recent years, the construction methods of precast prestressed concrete beam bridges by using tendon have been increasingly proposed. The properties of flexural tensile strength between precast prestressed concrete beam and cast-in-place concrete is an important factor that affects the structural performance. This paper aims at evaluating the tensile strength between old and new concrete. Tensile strength gain, with age after placing new concrete was evaluated. Test results show that the tensile strength between old and new concrete is much smaller than that of monolithic concrete. Also, it is shown that the curing condition of concrete has the tremendous effect on tensile strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.387-392
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• 2002

In many years, post-tensioning method has been used for structural reinforcement of RC structures due to easy installation and good quality control. This study presents practical application results for the effectiveness of structural post-tensioning reinforcement of the FCM bridge girders, cement silos and building girders. For the FCM bridges deflected excessively at the end of girders, for cement silos cracked vertically at silo surface and for building girders deflected due to heavy load from roof, the external post-tensioning method was used for uplifting deflected girders and closing cracks with increasing resisting capacity of the structures. It was demonstrated that all the items were rehabilitated nearly to the initial construction status according to the field test results.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.111-118
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• 2014

While large-sized facilities (type I II) have been managed systematically after the establishment of the Special Law for Safety Management on Facility, the management of small-sized facilities is relatively poor. The small-sized facilities have been managed by The Basic Law for Disaster and Safety Management, however, it is hard to manage them systematically as related standards are not established. Therefore, this study proposed the management plans for including the facilities such as some road tunnels and utility tunnels, which have the definite manager and a high possibility to harm the public, into type I and II facilities. In addition, it proposed the reinforcement plans of safety management for small-sized and vulnerable facilities such as breast wall and cut slopes, traditional markets and pedestrian bridges, which are fundamental facilities closely related to people's life, although a budget and a man-power are not enough.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.218-223
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• 2000

In the last years by the recognition and social capital maintenance of join local people of importance of bridge scenery and design we have get new business, and we have real understood the reflection which be given to the users sensitivity engineering science. We make as object the bridge and subject the design and with questionnaire we make an examine. we made verification of each different judgment. we applied the social capital maintenance into the sensitivity engineering science and discuss about how we can tie the design.