Speed management in Korea currently emphasizes the setting of speed limits and controlling vehicle speeds to align with these standards. However, monitoring safe and stable speeds tailored to specific road sections is essential for enhancing pedestrian safety in urban areas. In this study, a crash frequency model was developed to define the speed stability range and identify the critical threshold at which the crash frequency changes rapidly. This threshold serves as a reference point for assessing the speed stability levels. Individual vehicle trajectory data collected from 20 road segments in Daejeon-si were used to calculate the speed-related safety evaluation indicators that served as input variables for the safety model. The speed stability range calculation incorporates speed-related indicators and road facility data from Daejeon-si, allowing the model to consider the surrounding infrastructure. The findings revealed that intersections and crosswalks are positively correlated with cumulative crash occurrences. Crash frequency predictions showed higher crash likelihoods at average driving speeds below 30 km/h, indicating that congested conditions at intersections or at peak times necessitate increased safety management. Measures for maintaining safe and appropriate vehicle speeds within identified safe ranges are critical. The speed stability range calculation methodology provides a foundation for establishing traffic safety management strategies that focus on speed control in urban areas. These results can guide the development of targeted safety interventions that prioritize pedestrian protection and optimize safe driving speeds across various road segments.

Recently marine accidents involving floating objects have been continuously increasing due to domestic coastal traffic conditions, and as a result cases of secondary-linked reduction gear damage have also occurred one after another. This research aims to evaluate the ship propulsion system safety through the analysis the effect of the torsional stress generated on the propeller shaft system when a rope or net is wrapped around a propeller at sea through theoretical analysis, simulation analysis, and ship empirical test.

To predict annual energy production (AEP) accurately in the wind farm where located in Seongsan, Jeju Island, Equivalent wind speed (EQ) which can consider vertical wind shear well than Hub height wind speed (HB) is calculated. AEP is produced by CFD model WindSim from National wind resource map. EQ shows a tendency to be underestimated about 2.7% (0.21 m/s) than HB. The difference becomes to be large at nighttime when wind shear is large. EQ can be also affected by atmospheric stability so that is classified by wind shear exponent (). AEP is increased by 11% when atmosphere becomes to be stabilized ( > 0.2) than it is convective ( < 0.1). However, it is found that extreme wind shear ( > 0.3) is hazardous for power generation. This results represent that AEP calculated by EQ can provide improved accuracy to short-term wind power forecast and wind resource assessment.

The robot mechanisms that were previously researched had only been conducted for the purpose of overcoming the obstacles stably at low speed driving and enhancing the stability against high speed circuitous driving, and yet, the mechanism satisfying two purposes. However, in order to stably drive with high speed on rough terrain, there is a need for satisfying both of these purposes, as well as testing the efficiency of the mechanisms at high speed driving. There, this paper simulated some of the passive mechanisms and focused on checking the performances of passive mechanisms through simulations and analyzing each mechanism on the basis of an evaluation index. The simulation was conducted by Adams (The Multi-body Dynamics Simulation Solution) and used various types of passive mechanisms which were introduced in the robotics field. As a result, the study confirmed that passive mechanisms have a number of situations that affect the driving stability on each direction of roll and pitch. Further study is needed about active mechanism.