• Journal of the Korea Institute of Building Construction
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• v.15 no.2
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• pp.185-192
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• 2015

Expansion joint is the essential element of the bridge in many cases. When the bridge faces chloride of preventing freezing on the surface of the bridge, the expansion joints is damaged significantly, thus this reduces service life and increases maintenance cost of the bridge. As a solution of this problem, new technology using high ductile materials for the joint without expansion joint was developed and in this research, crack control performance, preventing leaking after the cracking, and chloride resistance were experimentally evaluated. As a result of the experiment, with PCM and FRC materials, the connecting joint suffered poor crack dispersion and severe damage by the chloride penetration while with high-ductile material, the connecting joint dispersed the tensile deformation to microcracks stably up to 7.5mm. Furthermore, under the sever conditions, the leaking was prevented and penetration of chloride ions was prevented after the crack occurred.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.441-448
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• 2020

In this study, the engineering characteristics of CLSM mixed with GBFS and GF were identified to review the applicability as a replacement material and further evaluate the recharge and field applicability as a joint filler material. This study has resulted in the following findings. First, Using more than 30% of GBFS to replace FA enabled bleeding control through improved fluidity. Moreover, it has been confirmed that effective strength and proper quality can be achieved when it was applied as a refiller and joint filler material with higher early strength than the base material. Second, When using more than 30% of FNS to replace sand, it was found that adding 0.3~0.35 of the AE agent is effective for bleeding control through improved fluidity. Third, When using more than 30% of both GBFS and FNS in combination, it was found that adding 0.3~0.35 of the AE agent is effective for bleeding control through improved fluidity. Also, it was confirmed that proper mixing of 15~60% of GF secured the effective strength and desired quality as a refiller and joint filler material. Fourth, The relationship between the superficial level and internal micro pores of CLSM from the curing process needs to be discussed and reviewed in more detail through further research studies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.105-111
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• 2003

Wheel for passenger car support the car weight with tires, and they transmit rolling and braking power into the ground. Whittling away at wheel weight is more effective to boost fuel economy than lighting vehicle body structure. A shape of hole in disk is optimized for minimizing the weight of steel wheel. Pro/ENGINEER program is used for formulating the design model, and ANSYS package is selected for analyzing the design model. It has difficulties to interface these commercial software directly. For Combining both programs, response surface methodology is applied to construct approximation functions for maximum stresses and maximum displacements are obtained by full factorial design of five levels. This steel wheel is modeled in 14-inch diameter of rim, and wide parameter of hole in disk is only selected as design variable for reducing the weight of steel whee. PLBA(Pshenichny-Lim-Belegundu-Arora) algorithm, which used the second-order information in the direction finding problem and uses the active set strategy, is used for solving optimization problems.

• Journal of the Korean Society for Railway
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• v.18 no.2
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• pp.94-104
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• 2015

Trams are rail vehicles that run on tracks along public, urban streets; they also sometimes run on separate rights of way. Tram vehicles run more efficiently and their overall operating costs are lower than those of similar vehicles. In general, trams provide a higher capacity service than buses. However, when tram stops in the middle of the road do not have pedestrian refuges, trams can cause speed reductions for other transport modes (buses, cars), as in such configurations other traffic cannot pass whilst passengers are alighting from or boarding the tram. In this study we examined the qualifications of overseas tram operation. The Railway Safety Act, sub-laws, and other relevant laws were examined to determine complementary measures.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.3
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• pp.1-9
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• 2011

The purpose of this study is to examine the dynamic characteristics of low, medium and high speed Maglev trains and guideways through dynamic interaction analysis. The coupled dynamic equations of motion for a vehicle of 10-dof and the associated guideway girders are developed by superposing vibration modes of the girder itself. The controller used in the UTM-01 Maglev vehicle is adopted to control the air gap between the bogie and guideway in this study. The effect of roughness, the guideway deflection-ratio and vehicle speed on the dynamic response of the maglev vehicle and guideway are then investigated using the 4th Runge-Kutta method. From the numerical simulation, it is found that the air gap increases with an increase of vehicle speed and the roughness condition. In particular, the dynamic magnification factor of the guideway girder is small at low and medium speeds, but the factor is noticeable at super-high speeds.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.487-500
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• 2010

The purpose of this study was to provide direction for national parks management policies by analyzing national park facility monitoring data collected every 2 years from 2002 to 2006. The results of this study showed the following. Firstly, 16 mountainous national parks showed increasing values in importance and performance in IPA. The trend analysis results showed that the location and capacity of parking lots as well as the number of rest rooms need to be improved. Secondly, two marine national parks indicated increasing values in campground and coastal facilities in IP value. Also, the location, number, and cleanliness of rest rooms, safety and surface condition of trail, guard rail and warning signs, information signs, drinking water fountains and shower facilities were priorities for improvement. The implications of this study will be able to help by providing guidelines for installation and maintenance of park facilities which in turn will improve visitor satisfaction and establish national park facility operation policies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.967-974
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• 2017

In this paper, a differential-braking-based yaw moment control system was developed to guarantee robust performance against road bank angle. A new target yaw rate model was established by combining the signal from a lateral acceleration sensor and 2-DOF single track model. In addition, a disturbance observer was utilized to take into account parameter uncertainties in yaw dynamics and to improve robust performance of the controller. CARSIM, which is a multi-DOF vehicle dynamic simulation tool, was used to verify the performance of the proposed controller in various driving scenarios. The simulation results indicate that the stability of the vehicle was robustly maintained by the controller, which is characterized by the reflection of the signal of a lateral acceleration sensor signal and by the compensation of the errors in the model parameters via the disturbance observer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.130-135
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• 2013

Anti-icing system can reduce traffic accidents and congestion by quickly removing the frozen road surface area. there is no decision criteria for determining application of the Anti-icing system in Korea. In this study, we proposed the decision criteria for determining application of the anti-icing system based on weather and road conditions, i.e., geometric and topographic conditions. Regional climate survey, Solar Radiation analysis, and dynamic vehicle simulation considered road geometry was conducted to standardize the installation method of anti-icing system. Also, we have developed a software that can be determined an installation of anti-icing system.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.295-301
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• 2019

Currently, the most commonly used decontamination agent in the country is calcium chloride, and the use of decontamination agents nationwide is on the rise due to climate change in the country. The deicing agent, aimed at deicing snow, is sprayed and the chloride is frozen and thawed by the dissolved surface water, causing various damages such as deterioration to the concrete. Therefore, in this study, the reactive urethane polymer was manufactured to coat concrete surface protection material, which is a method that prevents moisture from externally penetrating by applying to concrete surfaces, and the mixing agent was selected through the size control of molecules and surface modification, and the properties of penetrant stiffening agents and the application method of concrete was evaluated.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.71-78
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• 2010

The road safety depend on many road factors like vertical alignment, horizontal alignment and road cross section angle. These data are hardly to get with drawings, and the real data are differ from drawings because of road pavement overlay, etc. To get these data, so many time and cost are needed, moreover it is dangerous work in heavy traffic road. In this study we obtained the road safety data with RoSSAV(Road Safety Survey & Analysis Vehicle) of Korea Institute of Construction Technology in accordance with traffic flow, and make analysis of road safety with the vertical alignment, horizontal alignment and road cross section angle data. We derived the safety improvement method in Young-dong accident prone spot and described detail method in this paper.