• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.363-367
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• 2009

The ship maneuverability is changed by the effects of the bank cushion and the squat in the restricted water area. It is difficult to test the ship maneuverability by the real ship in the restricted water area because of ship's safety. In this study, a numerical model ship was used to simulate the ship's motion and to get information about the bank cushion and the squat in the restricted water area. The less apart from the quay the ship ran, the more ship's heading changed. The greatest change of ship's heading was $22.37^{\circ}$ when a ratio of the length between ship and quay to ship's breadh(=D/B) was 0.2. The squat of the ship was greater in shallower water and at faster speed. The greatest squat was 0.29m when a ratio of water depth to ship's draft(H/d) was 1.25 and ship's speed was 8 knots, the reduced speed was found to be the most important factor in the shallow water area for safety of the ship.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.3
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• pp.39-48
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• 2010

Improved seismic performances of RC bridges can be attained by sufficient ductilities of piers, which can be obtained by providing sufficient lateral confinements to the plastic hinge regions of piers. The cross sectional shape and the amount of lateral reinforcements are key parameters in the determination of effective confinements. Even though identical amounts of lateral reinforcement are provided, the effective confinement differs due to different spacing, arrangements, hook details and so on. Unlike circular sections in which confinement is exerted by mere hoop reinforcements, cross-ties are arranged in square or rectangular sections to enhance the effective confinements. The stress-strain relationship of confined concrete is varied by how to consider these cross-ties. In this study, the stress-strain relationships of confined concrete with cross-ties are investigated experimentally and their mechanical characteristics are estimated by comparison with other empirical equations.

• The Journal of the Korea Contents Association
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• v.15 no.4
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• pp.530-544
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• 2015

We live in the modern society which is called as Knowledge-Information society. The national and social goal is to raise the creative person for preparing the rapidly changing society. Thus, the schools and families concentrate on and effort to enhance the creativity and problem solving ability. Specially, the school is pushing forward the STEAM education and Software education for raising the creativity person and enhancement of national competitiveness. In this study, we suggested for STEAM education the way how we utilize the App Inventor which was supported by MIT and came up as a computer programming language for Software education, and we verified and evaluated through professional group verification. We completed STEAM instructional design according to the results from the professional group verification, and we suggested the authentic instruction for STEAM education. In addition, we suggested the further prospects of Software education and instructions through going through the characteristics and application plan of App Inventer in terms of educational computer programming language.

• Journal of Navigation and Port Research
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• v.34 no.8
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• pp.609-614
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• 2010

This paper describes statistical parameter estimation to calculate collision probabilities between Mokpo Harbor Bridge and passing vessels. At first, we obtained AIS (Automatic Identification System) information from passing vessels, then after, analyzed the lateral distributions of vessel tracks and estimated the mean and the standard deviation for the distance away from bridge center, the passing course and the passing speed. The analysis results of track distribution for the distance away and the passing course are shown as normal type, otherwise the speed distribution shown as two kinds of different normal type. In addition, we testified that the usefulness of estimated parameter values through the relative comparison between the track distributions and it's normal probability distributions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.531-538
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• 2017

A flush air data sensing system, which can predict flight speed, angle of attack, and angle of sideslip of the aircraft is designed and manufactured for a small UAV. Two kinds of flush pressure ports, four ports and five ports, are tapped at the same section of fuselage nose-cone. Calibration pressure data at flush ports are obtained through computations for the total aircraft by using Fluent code. Angle of attack, angle of sideslip, total pressure, and static pressure are represented with 4th-order polynomial function and calibration coefficient matrix is obtained using least square method with calibration pressure data. Flight test showed that flight speed, angle of attack, and sideslip angle predicted by four flush ports and five flush ports compared well with those by five-hole probe installed for data comparison. Especially four flush ports revealed nearly same results as those by five flush ports.

• Proceedings of KOSOMES biannual meeting
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• 2004.11a
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• pp.57-62
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• 2004

A mariner feels the ship-handling difficulty when the vessel onboard passes through breakwater. Until now, there is no a layout design of breakwater to take into account the ship-handling difficulty for the mariner. 11Us paper reproduced this situation which ship-handling is difficult by using marine traffic flow simulation, and it applied to Environmental Stress Model as the assessment model which is a quantitative model for evaluating the difficulty of ship-handling arising from restriction in maneuvering water areas and arising from traffic congestion The results are as follows. (1) The layout change of breakwater has little influence for reduction of ship-handling difficulty in the areas of vessel traffic volume. (2) In the situation of same breakwater width, difference of ship speed has an effect on decrease of ship-handling difficulty. (3) Expansion of breakwater width decreases ship-handling difficulty quantitatively.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.174-180
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• 2018

In this study, the propagation characteristics of Lamb waves in anisotropic silicon wafers of (100) and (111) direction were investigated by PVDF (Polyvinylidene Fluoride) line-focused transducer. The modified V(f,z) method was used because the Lamb waves are dispersive. For confirming the anisotropy, a line-focused transducer was used and the silicon wafer was rotated 180 degrees at intervals of 1 degree. As a result, $A_0$ and $S_0$ modes were observed. The speed of $S_0$ mode according to propagation direction showed anisotropy which is associated with the crystal structure, and the speed of $A_0$ mode was isotropic. The result is consistent with the crystal structure of silicon and the mechanism of vibration of each Lamb wave modes.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.6
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• pp.76-87
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• 1998

This paper deals with a system which recognizes dynmic hand gestures, Korean Sign Language(KSL), mixed with static hand gesture, Korean Manual Alphabet(KMA), continuously. Recognition of continuous hand gestures is very difficult for lack of explicit tokens indicating beginning and ending of signs and for complexity of each gesture. In this paper, state automata is used for segmenting sequential signs into individual ones, and basic elements of KSL and KMA, which consist of 14 hand directions, 23 hand postures and 14 hand orientations are used for recognition of complex gestures under consideration of expandability. Using a pair of CyberGlove and Polhemus sensor, this system recognizes 131 Korean signs and 31 KMA's in real-time with recognition rate 94.3% for KSL excluding no recognition case and 96.7% for KMA.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.5
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• pp.379-384
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• 2013

For effective ship management in VTS(Vessel Traffic Service), it needs to assess the external force acting on ship. Big data in maritime traffic can be roughly categorized into two groups. One is the traffic information including ship's particulars. The other is the external force information e.g., wind, sea wave, tidal current. This paper proposes the method to assess the external force acting on ship using big data in maritime traffic. To approach Big data in maritime traffic, we propose the Waterway External Force Code(WEF code) which consist of wind, wave, tidal and current information, Speed Over the Water(SOW) of each ship, weather information. As a results, the external force acting a navigating ship is estimated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.12
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• pp.1028-1036
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• 2014

A design procedure is established for hypersonic nozzles by using MOC(Method of Characteristics) and CFD. The inviscid nozzle contour is designed by MOC, then BLC(Boundary Layer Correction) is made by evaluating the boundary layer thickness from viscous CFD analysis. By comparing various definitions of the boundary layer thicknesses, it seems that the boundary layer thickness of 95% speed of the maximum value at the cross section satisfies best the design Mach number. Design procedure is as follow; MOC design, grid generation, inviscid analysis, viscous analysis, BLC and viscous analysis for confirmation and post-processing. All procedures are made automatically by using the batch processing.