• Journal of Magnetics
• /
• v.18 no.4
• /
• pp.487-493
• /
• 2013

The automotive industry is showing widespread interest in belt-driven electric motor-assisted (e-Assist) systems. A belt-driven assist system (BAS) starts and assists the combustion engine in place of the conventional generator. In this study, a water-cooled wound rotor synchronous motor (WRSM) for the e-Assist system was designed and analyzed. The performance of the WRSM was compared with that of an interior permanent magnet synchronous motor (IPMSM). The WRSM efficiency can be improved for the BAS by adjusting the field flux at high speeds. The field current map to obtain the maximum efficiency based on the speed and torque was developed. To control the field flux via field current control in the WRSM, a general H-bridge circuit was added to the WRSM inverter to get the rapid current response in the high-speed region; the characteristics were compared with the chopper circuit. A WRSM developed for the belt-driven e-Assist system and a prototype 115 V power electronic converter to drive the WRSM were tested with a 900 cc combustion engine. The test results showed that the WRSM-type e-Assist system had good characteristics and could successfully start and assist the 900 cc combustion engine.

• International Journal of Highway Engineering
• /
• v.3 no.4 s.10
• /
• pp.93-103
• /
• 2001

This study focused on the field applicability evaluation of SB latex-modified concrete (LMC) for concrete bridge deck overlay using mobile mixer. The main experimental factors were water-cement ratio(31, 33, 35 37%), latex contents(0, 5, 10, 15, 20%), and fine aggregate ratio(55, 56, 57, 58%) in order to evaluate the workability, mechanical properties, and durability property of LMC. The slump loss, air content, compressive and flexible strength tests were used to evaluate LMC workability and strength properties. Also, the rapid chloride permeability test was used to evaluate the relative permeability of LMC. As a results, the LMC with enough workability and good quality was produced when it was mixed in field using mobile mixer, satisfying the target compressive strength and flexural strength. The required water-cement ratio of LMC for same workability when mixing with mobile mixer was less than that when mixing in laboratory. Increasing the amount of latex produced concrete with increased flexural strength by mobile mixer. The required cement-water ratios for same initial $19{\pm}3cm$ slump were 37% and 33% at laboratory and mobile mixer, respectively. The mobile mixer was accurately calibrated satisfying the required specification.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.5 no.3
• /
• pp.173-180
• /
• 2001

In the past few years, the nondestructive inspection technology has greatly developed due to the increased necessity to gain a complete understanding of the bridge behavior. Especially, the deformations of bridges contain a lot of informations about its health state. By measuring these deformations it is possible to analyze the loading and aging behavior of the structure. However, the current, methods (such as LVDT, dial gage, optical displacement transducer, etc) are often of changeable application on site and have the limitations of installation. In this paper, the classical beam theory was reviewed and the deflections of structure are estimated using measured strain which is easy to acquire. The applicability of this algorithm is verified by laboratory(simple reinforced concrete beam) and field test. By this test, we proposed correction factor to estimate deflection of reinforced concrete beam after cracking, and analyze about the generation of correction factor. Also fiber optic sensors as well as resistive strain gages were installed in the concrete beams to establish the applicability of fiber optic sensors in the field of civil engineering.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10a
• /
• pp.467-472
• /
• 2000

It is known that chloride ion in concrete destroys the passive film of reinforcement inside concrete and accelerates corrosion which is the most influencing factor to durability of concrete structures. In this thesis, a chloride ion diffusion model for blast furnace slag(BFS) concrete, which has better resistance to both damage due to salt and chloride ion penetration than ordinary portland cement concrete, is proposed by modifying existing model of normal concrete. Proposed model is verified by comparing diffusion analysis results with both results by indoor chloride penetration test for specimens and field test results for actual RC bridge pier. Also, the optimum resistance condition to chloride penetration is obtained according to degrees of fineness and replacement ratios of BFS concrete. As a result, resistance to chloride ion penetration for BFS concrete is more affected by replacement ratio than degree of fineness.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2001.09a
• /
• pp.302-310
• /
• 2001

In order to lessen cable vibration, new cable damper system with high damping rubber was developed using the basis of the LRB design scheme. The analysis model of cable damper system incorporate voigt-kelvin damper model into the nonlinear cable analysis model. To achieve maximum damping capacity both reducing damper stiffness and developing high damping rubber were performed. As a result of verification test, the high damping rubber damper shows its effectiveness in improving cable damping capacity.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1995.10a
• /
• pp.132-141
• /
• 1995

This study is intended to propose practical but systematic and rational approaches for proof load test and integrity assessment of segmental PC box-girder bridges. The proposed models cover the whole range of field tests and assessment of such as inspections, nondestructive tests, static and dynamic load tests, structural analysis, and integrity assessment for the evaluation of load carrying capacity, serviceability, and durability of PC box-girder bridges. They are applied to a newly constructed precast segmental PC box-girder bridge which is a part of the Seoul interior circuit elevated expressway.

• Steel and Composite Structures
• /
• v.27 no.2
• /
• pp.217-227
• /
• 2018

This paper utilizes 3D FEM to provide deeper insights about the structural behaviour of a 6.1 m span steel culvert, which was previously tested under extreme loading. The effect of different input parameters pertaining to the backfill soil has been investigated, where the structural response is compared to field measurements. The interface choice between the steel and soil materials was also studied. The results enabled to realize the major influence of the friction angle on the load effects. Moreover, the analyses showed some differences concerning the estimation of failure load, whereas reasons beyond this outcome were arguably presented and discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.513-516
• /
• 2004

Consistency in design, manufacture, installation and performance test of expansion joints is insufficient for guarantee of reliability because they are imported from various foreign countries as America, Japan and Europe. In addition to that, the regulations or codes of expansion joint should be revised and established for levels of vibration and noise generated from riding vehicles especially. Regulation on the noise neighboring traffic roads is established by ministry of environment. Therefore, Field tests on the vibration and the noise at expansion Joints, especially rail-type and finger-type joints which are typical ones in bridge with short or middle span, are performed and performance of expansion joints are analyzed. And so, the results of the investigation will be utilized as basic data for the regulation on the vibration and the noise.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.2
• /
• pp.75-83
• /
• 2019

In this study, to propose the deterioration curves of urethane, ceramic, polysiloxane and fluorocarbon coating for the steel bridge, an accelerated corrosion tests were carried out. The each coating system wes applied on the top of the specimens, and circular initial defects were introduced with different diameters with 0.5, 1.0, 3.0, 5.0 mm. An accelerated corrosion test condition was used to simulate severe corrosive environment depending on ISO 20340. The deterioration curve of each coating type was evaluated based on deteriorated area from the circular defects. In order to evaluate the coating service life of installed steel bridge using deterioration curve, the acceleration coefficient was calculated at correlation between ISO 20340 and corrosivity categories by ISO 9223 based on field corrosion rate. From test results, the propagation rate of coating deterioration area was different to diameter of circular defects. In case of urethane coating, the coating service lifes of 3% deterioration area was evaluated in 31.8, 15.8, 9.9 and 3.9 years with C2, C3, C4 and C5 category.

• Transactions of the KSME C: Technology and Education
• /
• v.1 no.1
• /
• pp.115-121
• /
• 2013

It is greatly expected that the technologies of durability enhancement and evaluation for the core structures of plant facilities, marine plant and bridge constructures will be greatly expanded in the plant industry fields. In this study, the actively ongoing applied cases were tried to be analyzed in the present domestic industry fields through the Ultrasonic Nanocrystalline Surface Modification (UNSM) and Ultrasonic Fatigue Test (UFT) technologies using ultrasonic elastic vibrational energy, and the new application technology to improve the durability of plant industry field, especially plant facilities, marine plant and core weld components of bridge constructures will be presented.