In this study, The recent national interest is focused on the welfare of the people, and new projects in the construction sector are being reduced, and the aging of infrastructure is not getting attention. In domestic case, most of the infrastructures were built in the 1970s to 1980s, and the road extension is also steadily increasing. Therefore, the costs to bridge maintenance from around 2010 by a similar route to that of advanced countries are also 4 times And it is time to pay attention to maintenance as well as construction. Therefore, a study was carried out on the valuation method considering bridge condition evaluation, which is a part of BIM library building and assembly program development. The proposed value evaluation method will be used as an index of the existence of bridges by comparing the cost required for maintenance and reinforcement of the target bridges and the costs required for dismantling and disposal in the bridge management system of the future program

In this study, to develop the basis of damage prediction system for abutment type rigid-frame bridge, measurement data is generated by artificially expressing damage by Abaqus, a commercial structural analysis program, and applied to machine-learning. The rigid-rame bridge structural analysis model is expressed as closely as possible to the actual bridge condition considering the specification, damage expression, analysis method, boundary condition, and load. CNN(Convolutional Neural Network), one of the neural network algorithm, is used for machine-learning and accuracy is confirmed when there was no measurement error as a result of machine learning.

This study investigates characteristics on inelastic flange local buckling of ultra high performance concrete (UHPC) plate supported by one edge. The UHPC plate were modeled using 3D shell elements (S4R) and analyzed using by geometric and material nonlinear analysis. The plates for FE analysis were supported by pined and fixed boundary conditions to considering constrained effects of one web. The inelastic local buckling strength from the FE analysis were evaluated according to the flange slenderness ratios. The results shows that material non-linearities of tensile behavior of UHPC highly affects the inelastic local buckling of UHPC plate.

This study investigates the flexural shear strength of ultra high performance concrete I-girder. The effect of aspect ratio on the flexural - shear strength of UHPC was analyzed using finite element analysis. The UHPC I-type girder was modeled using 3D shell elements and analyzed using geometric and material nonlinear analysis. The boundary condition is simple support condition and a displacement load is applied to the center of the upper flange. The results shows that shear strength decreased as the aspect ratio increased and the bending-shear failure of UHPC I-girder does not occur even at larger moment than ordinary concrete due to the cross-linking action of steel fiber.

For the purpose of economic growth in the nineteenth century, social infrastructures have been rapidly aging since the 21st century, Currently, many of the existing infrastructure has been aged, and many national costs have been spent on safety Inspection and maintenance. It is expected that more maintenance will be costly in the future, and maintenance cost can be expected to be reduced due to safety inspection and repair and reinforcement measures in a timely manner. The measures provided in the national and international safety inspection and maintenance manual reduce the efficiency of the work by repeating document work. In addition, due to lack of information sharing among practitioners performing inspection and maintenance, it is considered that incomplete work or incurring additional costs will lead to a large national loss. Building Information Modeling (BIM) can manage all the information generated during the whole life cycle of social infrastructures. Domestic institutions are increasing the use of BIM, and the Public Procurement Service is obliged to design BIM. We expect to increase the work efficiency of practitioners by reducing repetitive document work using BIM, It will make the integrated management information enable bi-directional communication among practitioners. First of all, building a library of social infrastructures and standardizing the information classification system and procedures for BIM application should be essential. As a result, standardization studies on standard information classification system and procedures based on representative bridges among social infrastructures were conducted.

In this study, new Continuously Variable Transmission(CVT) system which is adaptable to a small size electric vehicle is proposed available to gradient response CVT. New pulleys consist of springs adapted driving pulley and driven pulley. At the moment a small electric vehicle drive a slope, new system respond to a gradient as overcoming tensional force of springs. We made prototype of gradient response CVT to test parts performance. As a result of test, belt pitch diameter varied for high torque direction at the gradient.

In this study variable radius pulley is proposed, and the proposal should be applied to pulley of CVT. Variable radius pulley consists of two disks and sliding pins. Phase difference of two disks make a change pitch diameter. Therefore change speed is accomplished by changing pitch diameter of pulley. In this paper simulation for slot variation of rotary disk of the variable radius pulley was performed. Softwares for simulation are Pro/Engineer5 and Hypermesh11.0. The results of simulation are appropriate to put to practical use of the variable radius pulley

The proposed cone type CVT(Continuously variable transmission) is consisted of drive pulley, belt, belt move equipment, tensioner, belt guide and driven pulley. In this study, the function and the relationship of all parts in the cone type CVT were investigated. The speed ratio of cone type CVT at case in parallel and incline movement of belt was analyzed. Proposed cone type CVT can apply to electrical vehicle, scooter and golf cart etc..

In this study variable radius pulley is proposed, and the proposal should be applied to pulley of CVT. Variable radius pulley consists of two disks and sliding pins. Phase difference of two disks make a change pitch diameter. Therefore change speed is accomplished by changing pitch diameter of pulley. In this paper analysis of rotating force for slot variation of the rotary disk of variable radius pulley was performed. The results of analysis are appropriate to put to practical use of the variable radius pulley.

In this study, new CVT system adapted for variable radius pulley is proposed to be available for pulley of CVT. Variable radius pulley consists of two disk and sliding pins joined by these disks. On account of phase difference of two disks, sliding pins move to radial direction and pitch diameter is varied. Therefore, change speed is accomplished by varying pitch diameter of pulley. CVT adapted for variable radius pulley is also performed with dynamometer test and axial distance variation. As a experimental result variable radius pulley can be alternative such as bicycle.

On cold start operation of an SI engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of spark timing. Combustion stability is also considered at the same time. Exhaust gas temperature and pressure of combustion chamber are measured to investigate the effects of spark timings on cold start and idle performance. Experiments showed that retarded spark timing promotes the combustion at the end of expansion stroke and increases exhaust gas temperature during cold start.

Dry CVT(Continuously variable transmission) consists of a driving pulley and a driven pulley joined by rubber V-belt. Each pulley consists of a fixed flange and a movable flange. The movable flange of the driving pulley has the centrifugal roller and a ramp plate in the flange. The movable flange moves toward a fixed flange under the actuation of a centrifugal roller, as the driving pulley speed increases. The main advantages of the Dry CVT with V-belt, which has been popular in Asia, are a simple mechanism, less maintenance and low cost. The important claim which have an influence on the performance of the Dry CVT is the wear of the centrifugal roller. In this study ball type is proposed instead of roller type of movable flange to resolve claim. Also experiments are carried out for new model to evaluate performances.

Dry CVT(Continuously variable transmission) consists of a driving pulley and a driven pulley joined by rubber V-belt. Each pulley consists of a fixed flange and a movable flange. The movable flange of the driving pulley has the centrifugal roller and a ramp plate in the flange. The movable flange moves toward a fixed flange under the actuation of a centrifugal roller, as the driving pulley speed increases. The main advantages of the Dry CVT with V-belt, which has been popular in Asia, are a simple mechanism, less maintenance and low cost. The important claim which have an influence on the performance of the Dry CVT is the wear of the centrifugal roller. In this study proposed an improved design of driving pulley reducing the wear of the centrifugal roller in order to provide some design guidelines.

On cold start operation of an SI engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of spark timing and exhaust valve timing. Combustion stability is also considered at the same time. Experiments showed that retarded spark timing promotes the combustion at the end of expansion stroke and increases exhaust gas temperature during cold start.An advance of exhaust valve timing decreases residual gas in cylinders due to decrease of valve overlap period. It helps improvement combustion stability by virtue of reduced residual gas. A control strategy of proper valve timing and spark timing is suggested in order to achieve fast light-off of the catalyst and stable operation of the engine in a cold start and idle operation

Over the past years, many research works have been carried out to investigate the factors which govern the performance of diesel engine. The air pollutant emission from the diesel engine is still a significant environmental concern in many countries. In the present study, new system of smoke reduction of diesel engine is proposed. This new system is using vacuum equipment and STS filter for capture smoke. To confirm new system experiments were performed at engine dynamometer. As a result of this experiment, the smoke reduction ratio of this system was identified high reduction ratio than PDPF. But the power of this system application was measured 10% decrease than base engine performance. There were improvement effects of using STS filter than ceramic filter.

On cold start operation of a gasoline engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of exhaust valve timing. An advance of exhaust valve timing decreases residual gas in cylinders due to decrease of valve overlap period. A control strategy of proper valve timing is suggested in order to achieve fast light-off of the catalyst and stable operation of the engine in a cold start and idle operation.