• International Journal of High-Rise Buildings
• /
• v.11 no.4
• /
• pp.301-314
• /
• 2022

Various studies have been conducted on pedestrian-level wind environments around buildings. With regard to the speed-up mechanism of pedestrian-level winds, there are references to downwash effect due to the vertical pressure gradient of boundary layer flow and venturi effect due to flow blocking by the building. Two factors contribute to increase or decrease of downwash effect: change in twodimensional / three-dimensional air flow pattern (Type 1) and change in downwash wind speed due to building size that does not accompany change in airflow pattern (Type 2). Previous studies have shown that downwash effect has a greater influence in increasing or decreasing the area of strong wind than venturi effect. However, these considerations are derived from the horizontal mean wind speed distribution at pedestrian level and are not the result of three-dimensional flow field around the building. Therefore, in this study, Computational Fluid Dynamics using Large Eddy Simulation were performed to verify the downwash phenomena that contributes to increase in wind speed at pedestrian level.

• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06a
• /
• pp.246-247
• /
• 2010

This paper proposes a fast motion estimation algorithm based on motion speed and multiple initial center points. The proposed method predicts initial search points by means of the spatio-temporal neighboring motion vectors. A dynamic search pattern based on motion speed and the predicted initial center points is proposed to quickly obtain the motion vector. Due to the usage of the spatio-temporal information and the dynamic search pattern, the proposed method greatly accelerates the search speed while maintaining a good predicted image quality. Experimental results show that the proposed method has a good predicted image quality in terms of PSNR with less search time as compared to the Full Search, New Three-Step Search, and Four-Step Search.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.4
• /
• pp.191-197
• /
• 2004

This paper presents experimental results for human drivers' driving patterns and an Adaptive Cruise Control(ACC) strategy. Analyses have shown that female drivers' driving characteristic values such as time-gap and minimum clearance are larger than those of male drivers'. Human drivers tend to have more clearance margins at high speed than at low speed. At low speed, drivers are much more sensitive to the desired clearance than at high speed. A multi-vehicle detection method is presented to improve ride quality of an ACC. Simulation results have shown that the proposed ACC can provide superior performance compared to the ACC strategy which uses a single-vehicle detection method.

• Journal of the Society of Naval Architects of Korea
• /
• v.41 no.2
• /
• pp.1-11
• /
• 2004

In this paper, the resistance characteristics of high-speed ship are studied in the region of shallow water condition. For the purpose of this research, model tests in a ship model basin are carried out with an equipment for the satisfaction of shallow water condition, and the computions of wave resistance characteristics and the flow simulations around a ship hull are performed by Michell's thin ship theory and a finite difference method based on MAC scheme, respectively. The calculation results for the resistance and flow characteristics of a ship hull are compared with those from the model tests in deep and shallow water conditions. From the comparison results, it is known that the variation of wave pattern around a ship hull caused by shallow water condition has the most influence to the resistance characteristics of a high-speed ship advancing on shallow water.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1132-1137
• /
• 2008

Automatic Operation based on ATO (Automatic Train Operation) is necessary for driverless Light Rail Transit business. When this kind of driverless LRT operation plan is made, TPS (Train Performance Simulation) is traditionally simulated at all-out mode and coasting mode based on manual operation. Commercial schedule speed equals to all-out speed minus $9{\sim}15%$ make-up margin. Coasting mode TPS simulation is also run at commercial schedule speed to calculate run time and energy consumption. But TPS based on manual operation should make an improvement on accuracy in case of driverless LRT operation Plan. In this paper, new fast mode TPS simulation using ATO pattern is proposed and show near actual ATO result. The actual ATO pattern can be accurately simulated with the introduction of 4 parameters such as commercial braking rate, jerk, station stop profile and grade converted distance. Normal mode TPS simulation for commercial schedule speed can be designed to have fast mode trip time plus 3 seconds/km margin recommended by korean standard LRT specification.

• Proceedings of the KSR Conference
• /
• 1999.11a
• /
• pp.534-541
• /
• 1999

The purpose of this study is to suggest the effective analytical procedure using finite element model for the crashworthiness of motorized trailer of high speed train. In the analysis of end-on collision of Motorized Trailer for Korean High Speed Train., deformed pattern, rigidwall force, internal energy and each part section force is obtained. From those indices, we evaluate crashworthiness of motorized trailer for Korean High Speed Train in planning. The numerical results are applied to the design of motorized trailer of Korean high speed train.

• Journal of the Korean Society of Physical Medicine
• /
• v.9 no.3
• /
• pp.285-291
• /
• 2014

PURPOSE: The purpose of this study was to propose clinical criteria to differentiate patients who are able to perform the step-through-step gait pattern in chronic stroke patients. METHODS: Sixty patients with chronic stroke patients participated this study. To differentiate patients who could perform the step-through-step gait pattern, age, gender, and causes of stroke were noted, a Chedoke-McMaster (CM) damage list, Fugl-Meyer (FM) assessment scales and the Berg Balance Scale (BBS) were determined. A 10 meter gait test and Timed Up and Go (TUG) test were conducted to determine the differences in gait speed and dynamic balance between patients walking with or without canes in the step-through-step gait pattern group. RESULTS: There was no significant statistical difference in age, gender, and stroke type between all subjects. There were significant differences in the CM scale for postural and lower extremities, and FM scale for lower extremities and BBS. The dynamic balance ability and gait speed showed significant differences between the subjects in the step-through-step gait pattern with or without a cane during gait. CONCLUSION: CM and FM scales for the lower extremities and postural control, as well as BBS scales, can be used as criteria to differentiate patients who are able to perform the step-through-step gait pattern. These results can also be used to provide beneficial information to patients that are walking with canes.

• Journal of International Academy of Physical Therapy Research
• /
• v.11 no.2
• /
• pp.2028-2035
• /
• 2020

Background: Weakness of the trunk muscles decreases the trunk control ability of stroke patients, which is significantly related to balance and gait. Objectives: To compare the impact of diagonal pattern self-exercise on an unstable surface and a stable surface for trunk rehabilitation on trunk control, balance, and gait ability in stroke patients. Design: Nonequivalent control group design. Methods: Twenty four participants were randomized into the experimental group (diagonal pattern self-exercise while sitting on an unstable surface, n=12) and the control group (diagonal pattern self-exercise while sitting on a stable surface, n=12). All interventions were conducted for 30 minutes, three times a week for four weeks, and the trunk impairment scale (TIS), berg balance scale (BBS), functional gait assessment (FGA), and G-walk were measured. Results: All groups indicated significant increases in all variables (TIS, BBS, FGA, cadence, speed, stride length) after four weeks. The TIS, BBS, FGA, cadence, gait speed, and stride length group-by-time were significantly different between the two groups. Conclusion: We found that, in stroke patients, diagonal pattern self-exercise on an unstable surface is a more effective method for improving trunk control, balance, and gait ability than diagonal pattern self-exercise on a stable surface.

• The KIPS Transactions:PartA
• /
• v.12A no.2 s.92
• /
• pp.87-94
• /
• 2005

Pattern matching is one of critical parts of Network Intrusion Prevention Systems (NIPS) and computationally intensive. To handle a large number of attack signature fattens increasing everyday, a network intrusion prevention system requires a multi pattern matching method that can meet the line speed of packet transfer. In this paper, we analyze Snort, a widely used open source network intrusion prevention/detection system, and its pattern matching characteristics. A multi pattern matching method for NIPS should efficiently handle a large number of patterns with a wide range of pattern lengths and case insensitive patterns matches. It should also be able to process multiple input characters in parallel. We propose a multi pattern matching hardware accelerator based on Shift-OR pattern matching algorithm. We evaluate the performance of the pattern matching accelerator under various assumptions. The performance evaluation shows that the pattern matching accelerator can be more than 80 times faster than the fastest software multi-pattern matching method used in Snort.

• Design & Manufacturing
• /
• v.17 no.4
• /
• pp.42-51
• /
• 2023

In this study, we investigated the injection molding technology of thick-walled light guides, which are parts that control the light source of automotive lamps. Through injection molding analysis, the gate position that can minimize product shrinkage and deformation was selected, and a mold reflecting the analysis results was manufactured to evaluate the effect of injection speed and holding pressure on transferability during micro-pattern molding through experiments. When designing an injection mold for products with varying thicknesses, it was found that installing the gate on the side of the thicker part was advantageous for reducing volume shrinkage and deformation. It was found that the effect of shrinkage due to thickness may be greater than the position of the gate on pattern transferability. The pattern transfer error decreased as the injection speed and holding pressure increased, and it was found that increasing the injection speed was relatively effective.