• Journal of Advanced Marine Engineering and Technology
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• v.30 no.1
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• pp.125-133
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• 2006

It is important to understand flow characteristics and performances of sails for both sailors and designers who want to have efficient thrust of yacht In this Paper the viscous flows around sail-like rigid wings, which are similar to main and jib sails of a 30 feet sloop, are calculated using a CFD tool. Lift, drag and thrust forces are estimated for various conditions of gap distance between the two sails and the center of effort of the sail system is obtained. Wind tunnel experiments are also carried out to measure aerodynamic forces acting on the sails system and to validate the computation. It is found that the combination of two sails produces the lift force larger than the sum of that produced separately by each sail and the gap distance between the two sails is an important factor to determine total lift and thrust.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.179-179
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• 2009

For the deposition of the semiconductor nanocrystals or quantum dots, it is required to have the substrates with smooth surface roughness. Slot-die coating method wad adopted and optimized varying the processing parameters like coating speed, gap distance, solution concentration, etc to get the smooth coated films on flexible substrates. The coating speed in slot-die method was varied from 1 m/min to 2.5 m/min focusing especially on its industrial usage. The gap distance between the substrate surface and slot-die lip was changed also to control mainly the thickness of coated films.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.121-125
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• 2000

This study was executed by dust explosion experiment of terephthalic acid which was widely used for various purposes of food packing material and film etc. and the demand was rapidly increasing. The particle size and concentration of dust affected the minimum ignition energy largely and the lean concentration and the minimum ignition energy in the range of this study were obtained 50$g/m^3$ and 19mJ respectively. Minimum ignition energy was shown at the 4 and 5mm gap distance of discharge electrode, and when the gap distance was below 2mm the explosion could not generated although the sufficient energy was given. It was also found that the ignition energy decreased linearly with the decreasing of dust mean particle size.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.832-839
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• 2005

It is important to understandflow characteristics and performances of sailsfor both sailors and designers who want to have efficient thrust of yacht. In this paper the viscous flows around sail-like rigid wings, which are similar to main and jib sails of a 30 feet sloop, are calculated using a CFD tool. Lift, drag and thrust forces are estimatedfor various conditions of gap distance between the two sails and the center of effort of the sail system is obtained. Wind tunnel experiments are also carried out to measure aerodynamic forces acting on the sail system and to validate the computation. It is found that the combination of two sails produces the lift force larger than the sum of that produced separately by each sail and the gap distance between the two sails is an important factor to determine total lift and thrust.

• Laser Solutions
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• v.14 no.3
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• pp.12-16
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• 2011

In automotive industry, because of the consideration of fuel economy, lightweight alloys have been adopted and are expected to be extensively used in the future. Magnesium alloys are among the promising materials, due to their lightweight and good mechanical properties. This study is related to the laser weldability of AZ31B magnesium alloy, an all-purpose wrought alloy with good strength and ductility. A 4kW Nd:YAG laser was used to join AZ31B sheet, and the effects of welding parameter on the quality of lap-welded joints were investigated. As a result of this study, the optimal condition was obtained, and the effect of gap distance was also revealed on the porosity control.

• Laser Solutions
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• v.5 no.2
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• pp.9-15
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• 2002

Basic principles and unique characteristics of laser-induced shock cleaning have been described compared to a conventional laser cleaning method and the removal of small tungsten particles from silicon wafer surfaces was attempted using both methods. It was found that the conventional laser cleaning was not feasible to remove the tungsten particles whereas a successful removal of the particles was carried out by the laser-induced shock waves. From the quantitative analysis using a surface scanner, the average removal efficiency of the particles was more than 98% where smaller particles were slightly more difficult to remove probably due to the increased adhesion force with a decrease of the particle size. It was also seen that the gap distance between the laser focus and the wafer surface is an important processing parameter since the removal efficiency is strongly dependent on the gap distance.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.235.1-235.1
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• 2002

In previous study, we showed the feasibility of the in vivo use of portable near infrared system for the determination of human skin moisture. In order to optimize the acquiring condition of NIR spectrum of skin. skin depth profiling was investigated changing the distance and gap size between illumination and receiving of radiation in the terminal of fiber probe. The colleted light information could be controlled depending the distance and gap of fiber optic probe. (omitted)

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.52-60
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• 2020

When a bubble reaches a free surface, a bursting of the bubble produces a high speed jet. Despite its practical importance, significant effort has been devoted to investigate a bursting jet by a single bubble near a free surface. In the present study, we perform numerical simulations of bubbles in a tandem arrangement at Bo=0.05. The configuration of the tandem bubbles is systematically varied by changing a radius of a following bubble (RF) and the gap distance between two bubbles (L). Compared to a single bubble case, we show that the bursting bubble in the tandem arrangement accelerates, and the jet velocity increases. Moreover, we find that a critical gap distance at which the jet velocity unexpectedly changes exists in the tandem case.

• Journal of Radiation Protection and Research
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• v.8 no.1
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• pp.33-37
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• 1983

Neutron reflecting effects in terms of effective multiplication factor have been calculated with varying water or concrete thickness, and gap distance between concrete reflector and a fissile solution system. A numerical calculation of effective multiplication factors has been carried out by using the discrete ordinates method with the help of the computer code, ANISN. It is revealed that the reflecting .effect by thin concrete is lower than that of the identical thickness of water while the effect by thick water is low compared to that of the identical thickness of concrete. It seems that the effective multiplication factors are first decreasing rapidly with gap distance, which is filled with water, between concrete reflector and the fissile solution system, and then decrease slowly over the distance of about 15cm.

• Journal of Information Processing Systems
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• v.20 no.2
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• pp.239-251
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• 2024

Coronavirus disease 2019 (COVID-19) has severely curtailed travelers' willingness to carpool and complicated the psychological processing system of travelers' carpooling decisions. In the post-COVID-19 era, a two-stage decision model under dynamic decision scenarios is constructed by tracking the psychological states of subjects in the face of multi-scenario carpooling decisions. Through a scenario experiment method, this paper investigates how three psychological variables, travelers' psychological distance to COVID-19, anticipated regret, and experienced regret about carpooling decisions, affect their willingness to carpool and re-carpool. The results show that in the initial carpooling decision, travelers' perception gap of anticipated regret positively predicts carpooling willingness and partially mediates between psychological distance to COVID-19 and carpooling willingness; in the re-carpooling decision, travelers' perception gap of anticipated regret mediates in the process of experienced regret influencing re-carpooling willingness; the inhibitory effect of experienced regret on carpooling in the context of COVID-19 is stronger than its facilitative effect on carpooling willingness. This paper tries to offer a fact-based decision-processing system for travelers.