• Transportation Technology and Policy
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• v.10 no.4
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• pp.14-20
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• 2013

• Structural Engineering and Mechanics
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• v.34 no.1
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• pp.139-142
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• 2010

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.162-170
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• 2004

In these days, a vehicle simulator is developed by using a VR(Virtual Reality) system. A VR system must provide a vehicle simulator with a natural interaction, a sufficient immersion and realistic images. To achieve this, it is important to provide a fast and uniform rendering performance regardless of the complexity of virtual worlds or the level of simulation. In this paper, modeling methods which offer an improved rendering performance for complex VR applications as 3D road model have been implemented and verified. The key idea of the methods is to reduce a load of VR system by means of LOD(Level of Detail), alpha blending texture mapping, texture mip-mapping and bilboard. Hence, in 3D road model where a simulation is complex or a scene is very large, the methods can provide uniform and acceptable frame rates. The VR system which is constructed with the methods has been experimented under the various application environments. It is confirmed that the proposed methods are effective and adequate to the VR system which associates with a vehicle simulator.

• Korean Journal of Agricultural Science
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• v.51 no.2
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• pp.133-146
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• 2024

Selection of gear reduction ratio is essential for machine design to ensure suitable power and speed during agricultural operations. The goal of the study was to evaluate the gear reduction ratio for a 1.6 kW four-wheel-drive (4WD) multi-purpose agricultural electric vehicle platform using workload data under different off-road conditions. A data acquisition system was fabricated to collect workload (torque) of the vehicle acting on the gear shaft. Field tests were performed under three driving surfaces (asphalt, concrete, and grassland), payload operations (981, 2,942, and 4,903 N), and slope conditions (0 - 4°, 4 - 8°, and 8 - 12°), respectively. Commercial speed reduction gear phases were attached to the input shaft of the vehicle powertrain. The maximum required torque was recorded as 37.5 Nm at a 4,903 N load with 8 - 12° slope levels, and the minimum torque was 12.32 Nm at 0 - 4° slope levels with a 981 Nm load for a 4 km/h speed on asphalt, concrete, and grassland roads. Based on the operating load condition and motor torque and rotational speed (TN) curve, the minimum and maximum gear reduction ratios were chosen as 1 : 50 and 1 : 64, respectively. The selected motor satisfied power requirements by meeting all working torque criteria with the gear reduction ratios. The chosen motor with a gear reduction ratio of 1 : 50 was suitable to fit with the motor T-N curve, and produced the maximum speeds and loads needed for driving and off-road activities. The findings of the study would assist in choosing a suitable gear reduction ratio for electric vehicle multi-purpose field operations.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.138-145
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• 2012

Because of the climate changes and the development of building technologies, the cooling loads have been increased. Among the various renewable energies, geothermal energy is known as very useful and stable energy for heating and cooling of building. This study proposes a road snow-melting system of which heat is supplied from GSHP(Ground source heat pump) in viewpoint of the initial investment and annual running performance, which is also operating as a main facility of heating and cooling for common spaces. The results of this study is as followings. From the site measurement, it is found out that the road surface temperature above the geothermal heating pipe rose up to $5^{\circ}C$, which is the design temperature of road snow-melting, after 2 hours' operation and average COP(Coefficient of performance) was estimated as 3.5. The reliability of CFD has confirmed, because the temperature difference between results of CFD analysis and site measurement is only ${\pm}0.4^{\circ}C$ and the trend of temperature variation is quite similar. CFD analysis on the effect of pavement materials clearly show that more than 2 hours is needed for snow-melting, if the road is paved by ascon or concrete. But the road paved by brick is not reached to $5^{\circ}C$ at all. To evaluate the feasibility of snow-melting system operated by a geothermal circulation which has not GSHP, the surface temperature of concrete-paved road rise up to $0^{\circ}C$ after 2 hour and 40 minutes, and it does never increase to $5^{\circ}C$. And the roads paved by ascon and brick is maintained as below $0^{\circ}C$ after 12 hours geothermal circulation.

• Smart Media Journal
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• v.10 no.4
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• pp.63-70
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• 2021

Public Signs guiding drivers on the road should help make decisions within a short period of time, so appropriate information should be effectively expressed at the point. Currently, the road marking rules revised by the law show a significant change in the type of information, expression method, and weight of expression compared to existing road signs to be based on road name addresses. This study analyzed whether the revised road signs changed based on the road name were effective in perspective of perception-cognition-understanding-projection and examined whether they provided appropriate information for the actual driving environment. Based on the analyzed information, an experiment was conducted to present an improved design, evaluate the degree of visibility compared to existing road name-oriented signs, and a qualitative investigation was conducted on the suitability of the sign contents. Through this, it is expected that more suitable driving information and measures to increase intuitive visibility can be reviewed.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1035-1040
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• 2024

South Korea has seen an increased demand for road maintenance, since they experienced a rapid industrialization in 1960-70s. Between 2019 and the end of 2022, the total national expenditure on road maintenance steadily rose from KRW 3.4 trillion to KRW 4.5 trillion. Roads, responsible for about 80% of the nation's transportation, significantly affect ride quality, safety and maintenance costs. Among the different perspectives, this study focuses on the prevalence of potholes. Over 24,000 pothole instances are reported on highways in the past five years, which raises concerns due to various direct and indirect effects on road maintenance and safety issues. Various methods, including vision-based, vibration-based, and 3D reconstruction-based techniques, have been proposed for pothole detection and inspection. Vision-based methods effectively count and measure pothole shapes but which are sensitive to lighting conditions. Vibration-based methods offer cost-effectiveness, although it may not provide precise pothole shape information. 3D reconstruction-based methods deliver accurate shape measurements, while it comes with higher costs. To establish an effective road maintenance system, prioritization criteria for potholes is required to be established and applied. These criteria may vary across countries or regions. For example, in the United States, potholes are classified based on depth into Low (<25mm deep), Moderate (25 to 50mm deep), and High (>50mm deep). In conclusion, this research addresses this research challenge of road damage and potholes in South Korea by exploring various pothole classification standards and utilizing advanced technology to develop an efficient road maintenance system. The outcome would benefit improved road infrastructure management and enhanced safety.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.4
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• pp.24-32
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• 2003

This study was carried out to select proper species for early stage replantation of forest road cut-slope. From one to fourteen year elapsed forest roads in Gangwon-do, sample plots were selected, and their vegetations and environmental factors were investigated. Invaded species with high frequency ordered Lespedeza cyrtobotrya, Lysimachia clethroides, Rubus crataegifolius, Patrinia villosa, Spodiopogon sibiricus, Pueraria thunbergiana, Youngia denticulata, Dactylis glomerata, Rhus chinensis, and Pinus densiflora. North cut-slope have the highest value of invaded species number and plant coverage, and so, north aspect could be best for plant invasion. According to ordination, distribution of species were influenced by elapsed year, cut-slope aspect, and cut-slope. Lespedeza bicolor, Lespedeza cyrtobotrya, Artemisia stolonifera, Miscanthus sinensis, Rubus crataegifolius, Rhus chinensis, Lindera obtusiloba, and Pinus densiflora were considered with proper species for replantation at south slope. Also, Lespedeza bicolor, Lespedeza cyrtobotrya, Arundinella hirta, Artemisia keiskeana, Astilbe chinensis var. davidii, Rubus crataegifolius, Weigela subsessilis, Stephanandra incisa, and Rhododendron mucronulatum were considered with proper species as replantation at north slope.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.184-190
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• 2015

NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

• International Journal of Automotive Technology
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• v.7 no.1
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• pp.25-34
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• 2006

For decades, simulation technique has been well validated in areas such as computer and communication systems. Recently, the technique has been much used in the area of transportation and traffic forecasting. Several methods have been proposed for investigating complex traffic flows. However, the dynamics of vehicles and diversities of driver characteristics have never been considered sufficiently in these methods, although they are considered important factors in traffic flow analysis. In this paper, we propose a traffic simulation tool called Multi-Agent for Traffic Simulation with Vehicle Dynamics Model (MATDYMO). Road transport consultants, traffic engineers and urban traffic control center managers are expected to use MATDYMO to efficiently simulate traffic flow. MATDYMO has four sub systems: the road management system, the vehicle motion control system, the driver management system, and the integration control system. The road management system simulates traffic flow for various traffic environments (e.g., multi-lane roads, nodes, virtual lanes, and signals); the vehicle motion control system constructs the vehicle agent by using various vehicle dynamic models; the driver management system constructs the driver agent capable of having different driving styles; and lastly, the integrated control system regulates the MATDYMO as a whole and observes the agents running in the system. The vehicle motion control system and driver management system are described in the companion paper. An interrupted and uninterrupted flow model were simulated, and the simulation results were verified by comparing them with the results from a commercial software, TRANSYT-7F. The simulation result of the uninterrupted flow model showed that the driver agent displayed human-like behavior ranging from slow and careful driving to fast and aggressive driving. The simulation of the interrupted flow model was implemented as two cases. The first case analyzed traffic flow as the traffic signals changed at different intervals and as the turning traffic volume changed. Second case analyzed the traffic flow as the traffic signals changed at different intervals and as the road length changed. The simulation results of the interrupted flow model showed that the close relationship between traffic state change and traffic signal interval.