• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.191-197
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• 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 Korea Institute of Military Science and Technology
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• v.21 no.1
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• pp.1-9
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• 2018

In this paper, we have proposed a prediction method for sabot-trajectory of projectile using high speed camera data analysis. Through analyzing trajectory of sabot with high speed camera data, we can extract its real velocity and acceleration including effects of friction force, pressure of flume, etc. Using these data, we suggest a prediction method for sabot-trajectory of projectile having variable acceleration, especially for minimum and maximum acceleration, by using interpolation method for velocity and acceleration data of sabot. Also we perform the projectile launching tests to achieve the trajectory of sabot in case of minimum and maximum thrust. Simulation results show that they are similar to real tests data, for example velocity, acceleration and the trajectory of sabot.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.751-758
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• 2000

In this paper, we discuss frequency allocation and sharing for high speed radio access network in domestic 5GHz the band. In order to evaluate the possibility of frequency sharing between meteorological radar and high speed radio access network, we analyses radio interference of meteorological radar by means of minimum coupling loss method and Monte Carlo simulation. And simulations show that it is necessary to use DFS(Dynamic Frequency Selection) scheme for frequency sharing between meteorological radar and high speed radio access network.

• Journal of computational fluids engineering
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• v.20 no.3
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• pp.62-69
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• 2015

Pressure change inside cabin as well as in tunnel has been calculated to assess the passenger pressure comfort of high-speed train. $C-STA^{TM}$, a CFD program based on axi-symmetric Navier-Stokes equation and Roe's FDS has been used to simulate the pressure change in tunnel during a high-speed train passing through it. To present the relative motion between the train and the tunnel, a modified patched grid scheme based on the structured grid system has been employed. The simulation program has been validated by comparing the simulation results with field measurements. Extensive parametric study has been conducted for various train speed, tunnel cross-sectional area and tunnel length to the pressure change in cabin. KTX-Sancheon(KTX2) high-speed train has been chosen for simulation and the train speed have been varied from 200 km/h to 375 km/h. The tunnel length has been varied from 300 m to 7.5 km and tunnel area from $50m^2$ to $120m^2$. Total 504 simulations have been conducted varying the parameters. Based on the database produced from the parametric simulations, minimum tunnel cross-sectional area has been surveyed for various train speeds based on Korean regulation on pressure change in cabin.

• Journal of Information Processing Systems
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• v.19 no.2
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• pp.149-163
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• 2023

Affected by external factors, errors in time series data collected by sensors are common. Using the traditional method of constraining the speed change rate to clean the errors can get good performance. However, they are only limited to the data of stable changing speed because of fixed constraint rules. Actually, data with uneven changing speed is common in practice. To solve this problem, an online cleaning algorithm for time series data based on dynamic speed change rate constraints is proposed in this paper. Since time series data usually changes periodically, we use the extreme learning machine to learn the law of speed changes from past data and predict the speed ranges that change over time to detect the data. In order to realize online data repair, a dual-window mechanism is proposed to transform the global optimal into the local optimal, and the traditional minimum change principle and median theorem are applied in the selection of the repair strategy. Aiming at the problem that the repair method based on the minimum change principle cannot correct consecutive abnormal points, through quantitative analysis, it is believed that the repair strategy should be the boundary of the repair candidate set. The experimental results obtained on the dataset show that the method proposed in this paper can get a better repair effect.

• Journal of Welding and Joining
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• v.21 no.7
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• pp.42-48
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• 2003

Welding distortion is a current issue in many industrial parts, especially for heavy industry such as shipbuilding, plant industry. The welding process has many processing parameters influencing welding angular distortion such as heat input power, welding speed, gas flow rate, plate thickness and the welded material properties, etc. In this work, the conventional local minimization concept was applied to find a set of optimum welding process parameters, consisted of welding speed, plate thickness and heat input, for a minimum angular distortion. An analytic solution for welding angular distortion, which is based on laminated plate theory, was also applied to investigate and optimize the welding process parameters. The optimized process parameters and the angular distortion for various parametric conditions could be easily found by using the local minimum concept.

• Journal of Korean Society of Transportation
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• v.13 no.3
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• pp.53-65
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• 1995

Proposed are model and its solution algorithm for determining the minimum number of high speed exits and their locations. While the previous researches on exit location aimed to minimize the average runway occuancy time (ROT) of an aircraft mix, the proposed approach is to find the minimum number of exits required to meet maximum allowable ROT. The rationale behind the approach is that the capacity of a runway increases as the ROT decreases down to some value, but not any more even though the ROT keep decreasing below the value. Hence, a maximum allowable ROT might be set up without declining the capacity. The problem is transformed into a shortest path problem on a specially constructed network and Dijkstra's labeling algorithms is employed to solve the problem A hypothetical example is provided to illustrate how the algorithms solves the problem.

• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.859-865
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• 2001

This paper reports on the theoretical analysis of mixed lubrication for the piston ring. The analytical model is presented by using the average flow and asperity contact model. The cyclic variations of the nominal minimum oil film thickness are obtained by numerical iterative method. The total friction is calculated by using the hydrodynamic and asperity contact theory. The effect of the roughness height, pattern, and engine speed on the nominal minimum film thickness, friction force, ad frictional power losses are investigated. As the roughness height increases, the nominal oil film thickness and total friction force increase. Also, the effect of the surface roughness on the boundary friction is dominant at low engine speed and high asperity height. The longitudinal roughness pattern shows lower mean oil film pressure and thinner oil film thickness compared to the case of the isotropic and transverse roughness patterns.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1160-1163
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• 1999

In this study, we developed FE-tip lithography system that could apply to multi-tip system and did lithography using FE-tip. The software that control FE-tip lithography system, was proposed for acquiring more adaptive data to compensate the effect of fluctuation. We found that the fluctuation effect was reduced. The minimum line width was related to applied voltage and we observed a movement of Z-axis piezo stage to correct the error of this system. When FE current was 5nA, scanning speed was $3{\mu}m/sec$ and applied voltage was 200V, we made a line pattern which had minimum line width of 614 nm. If we reduce applied voltage to several decades and increase scanning speed to $20{\mu}m/sec$, it is possible to set the minimum line width of 100 nm. The proposed system can be easily applied to multi FE-tip lithography system.

• Tribology and Lubricants
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• v.17 no.4
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• pp.290-296
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• 2001

Lift-off means that the rotating journal surface separates from the leaf surface in an air-lubricated multi-leaf foil journal bearing. Lift-off builds up minimum film thickness which will provide load capacity between leaves and journal. In this paper an analysis of air-lubricated multi-leaf foil journal bearing was performed with effects of multi-leaf foil deflection and compressible lubrication equation simultaneously. Minimum film thickness built up versus journal speed predicts the lift off characteristics and these results will be useful in designing and selecting the proper speed of the air-lubricated multi-leaf foil journal bearing.