• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.62-70
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• 2016

Increased bus traffic leads inefficiency at near-side bus stops in median exclusive bus lane because buses are waiting for a signal does not have a vehicle arrived. This study suggests a method for estimating a proper spacing between bus stops and signalized intersection to prevent the inefficiency. We modified the Poisson model for a proper spacing by using both dwell time and waiting time of signal instead of using dwell time only. The waiting time of signal changes by spacing and it was measured using micro simulation program. The iterative algorithm using the change of waiting time of signal was also suggested. By applying the proposed method, measure waiting time by simulation and iterative algorithm, the spacing of near-side bus stops, proper spacing is suggested according to flow rate level.

• Journal of Korea Foundry Society
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• v.27 no.6
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• pp.243-249
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• 2007

The effect of Re addition and solidification rate on the directional solidification behavior of Ni-Al model alloy has been investigated. Directional solidification (DS) were carried out using the modified Bridgman furnace with various solidification rates. The solid/liquid interface during directional solidification was preserved by quenching the specimen after the desired volume fraction of original liquid was solidified. The equilibrium partition coefficients of Al and Re Were estimated by measuring the compositions at the quenched solid/liquid interface. Then, the effect of Re addition on the elemental segregation behavior was carefully analyzed. The differential scanning calorimetry results showed that the Re addition results in increased ${\gamma}'$ solvus and freezing range of the alloy. It was also shown that the primary dendrite arm spacing gradually decreases with increasing the Re content, while the secondary dendrite arm spacing appears to be independent on the Re content. The compositional analyses clearly revealed that the segregation of Al increased with increasing the Re content and solidification rate, while that of Re was found to be independent on the solidification rate in the range of $10{\sim}100{\mu}m/s$ due to its sluggish diffusion rate in the Ni solid solution.

• Proceedings of the ESK Conference
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• 1998.04a
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• pp.161-166
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• 1998

In this study, the optimum criteria of space between the lines and the letters which could largely affect the legibility were found by the experiment and were presented as guidelines to design Korean VDT screens. Since the experiment was designed to test the human performance based on the VDT screen design, searching speed (S.S) and error rate (E) were used as the criteria of performance, and CFF value was measured to evaluate user's visual fatigue. The EOG value was also measured for the visual restriction during the experiment for the space between the lines and letters.

• Journal of Biosystems Engineering
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• v.26 no.2
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• pp.115-122
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• 2001

An impact-type seed-metering device was developed for the planting of rice-pellets. In this study, new design of pellet-metering device focused on simplicity and precision seeding for the planting of rice-seed pellets. In addition of seed-metering device, several devices were also developed such as seed-guiding device, seed-supplying tube and furrow opener for precision pellet planting. Field test was conducted to estimate the planting performance of the developed metering device. As a cam rotates, the impact bar of the metering device pushes a rice-seed pellet so that the seed can be discharged from the seed-supplying tube in the impact-type seed-metering device. Results of the tests showed that mean seeding spacing was 12cm at the traveling speed of 1.0m/s, corresponding to a target spacing for planting of rice-seed pellets. Also, both miss-seeded rate and damaged-seed rate were less than 2.0%, indicating acceptable levels for the precision planting. The developed mechanism of the impact-type metering device can be directly applied to the design of metering devices for the precision pellet planting of other crops.

• Advances in aircraft and spacecraft science
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• v.10 no.3
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• pp.203-222
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• 2023

The detonation combustion is a supersonic combustion process follows on shock wave oscillations in detonation tube. In this paper numerical studies are carried out combined effect of blockage ratio and spacing of obstacle on detonation wave propagation of hydrogen-air mixture in pulse detonation combustor. The deflagration to detonation transition of stoichiometric (ϕ=1)fuel-air mixture in channel has been analyzed for effect of blockage ratio (BR)=0.39, 0.51, 0.59, 0.71 with spacing of 2D and 3D. The reactive Navier-Stokes equation is used to solve the detonation wave propagation mechanism in Ansys Fluent platform. The result shows that fully developed detonation wave initiation regime is observed near smaller vortex generator ratio of BR=0.39 inside the combustor. The turbulent rate of reaction has also a great significance role for shock wave structure. However, vortices of rapid detonation wave are appears near thin boundary layer of each obstacle. Finally, detonation combustor demonstrates the superiority of pressure gain combustor with turbulent rate of reaction of 0.6 kg mol/m3 -s inside the detonation tube with obstacle spacing of 12 cm, this blockage enhanced the turbulence intensity and propulsive thrust. The successful detonation wave propagation speed is achieved in shortest possible time of 0.031s with a significance magnitude of 2349 m/s, which is higher than Chapman-Jouguet (C-J) velocity of 1848 m/s. Furthermore, stronger propulsive thrust force of 36.82 N is generated in pulse time of 0.031s.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.1
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• pp.82-96
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• 2024

While analyzing traffic flow, speed, traffic volume, and density are important macroscopic indicators, and acceleration and spacing are the important microscopic indicators. The speed and traffic volume can be collected with the currently installed traffic information collection devices. However, acceleration and spacing data are necessary for safety and autonomous driving but cannot be collected using the current traffic information collection devices. 'You Look Only Once'(YOLO), an object recognition technique, has excellent accuracy and real-time performance and is used in various fields, including the transportation field. In this study, to measure acceleration and spacing using YOLO, we developed a model that measures acceleration and spacing through changes in vehicle speed at each interval and the differences in the travel time between vehicles by setting the measurement intervals closely. It was confirmed that the range of acceleration and spacing is different depending on the traffic characteristics of each point, and a comparative analysis was performed according to the reference distance and screen angle to secure the measurement rate. The measurement interval was 20m, and the closer the angle was to a right angle, the higher the measurement rate. These results will contribute to the analysis of safety by intersection and the domestic vehicle behavior model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.1
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• pp.67-73
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• 2009

The stress-strain behavior and its effects on the crack initiation and growth of ITO film on PET substrate with a sheet resistance of 45 ohms/sq were investigated. Electrical resistance increased gradually at the strain of 0.7% in the elastic to plastic transition region of the stress strain curves. Numerous cracks were observed after 1% strain and the increase of the resistance can be linked to the cracking of ITO thin films. The onset strain for the increase of resistance increased with increasing strain rate, suggesting the crack initiation is dependent on the strain rate. Upon loading, the initial cracks perpendicular to the tensile axis were observed and propagated the whole sample width with increasing strain. The spacing between horizontal cracks is thought to be determined by the fracture strength and the interfacial strength between ITO and PET. The crack density increased with increasing strain. The spacing between horizontal cracks (perpendicular to the stress axis) increased with decreasing strain rate, The increase of crack density with decreasing strain rate can be attributed to the higher fraction of the plastic strain to the total strain at a given total strain. As the strain increased over 5% strain, cracks parallel to the stress axis were developed and increased in number with strain, accompanied by drastic increases of resistance.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1996.11a
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• pp.72-75
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• 1996

The objectives of this paper investigate the effect of installed spacing on the activation of spot type heat detection devices. The flow of hot gases under a ceiling resulting from the impingement of a fire plume activates heat detectors and sprinklers. Local temperature and velocity in this ceiling jet are usually expressed with the function of a ceiling height, the distance from a fire location and the heat release rate of fire. And detectors having different. RTI respond in different ways to the same temperature and velocity of ceiling jet. Thus great care should be taken to decide installed spacing of heat detection devices by considering above effects.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.443-444
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• 2002

The uniformity of field oxide is critical to isolation property of device in STI, so the control of field oxide thickness in STI-CMP becomes enormously important. The loss of field oxide in shallow trench isolation comes mainly from dishing and erosion in STI-CMP. In this paper, the effect of slurries on the dishing was investigated with both blanket and patterned wafers were selected to measure the removal rate, selectivity and dishing amount. Dishing was a strong function of pattern spacing and types of slurries. Dishing was significantly decreased with decreasing pattern spacing for both slurries. Significantly lower dishing with ceria based slurry than with silica based slurry were achieved when narrow pattern spacing were used. Possible dishing mechanism with two different slurries were discussed based on the observed experimental results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.674-682
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• 1998

In this study, thin film evaporation of water on low-fin tubes were experimentally investigated. Five low-fin tubes with different fin spacing and fin height were tested. Test range covered 0.146kg/ms $\leq$$\Gamma$$\leq$0.219kg/ms and 10㎾/$\m^2$$\leq$q $\leq$70㎾/$\m^2$. Saturation temperature was loot. Compared with the plain tube, low fin tubes enhanced the water film evaporation from 60% to 100%. Tubes with fin spacing smaller than 2mm and fin height higher than 1mm performed better than tubes with other fin configuration. However, when fin spacing was too small at high film flow or fin height was too high at low film flow, the performance decreased. The heat transfer coefficient slightly increased as the flow rate increased. Correlations are developed based on present data.