• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.53-58
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• 2022

Since a general household fan has only one left/right turning stage, the rotation angle cannot be adjusted leading to cases whether the wind reaches to an unnecessary area or vice versa. In this paper, we propose a method to efficiently control the turning section to selectively send wind to a necessary space while reducing energy waste. The minimum rotation angle was obtained by experimentally measured the stationary wind direction angle of the fan, and the optimal number of turning stages was selected by appropriately dividing the space where the wind reaches. Through this, it was confirmed that if the fan has a minimum rotation angle of 45°, a turning section of 3 stages and its rotation angle is increased by twice the stationary wind direction angle at each stage, the wind is distributed efficiently. Therefore, it is considered that the selective turning stage control proposed in this paper can minimize energy waste without significant change of the fan structure.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.497-503
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• 2018

Passenger ships and training ships have a common feature in that they serve many passengers. Thus, safe navigation is very important. During normal sailing, a ship may turn using various types of steering, including maneuvers to avoid collisions with dangerous target. When a ship turns, a heeling angle occurs. If trouble arises during sailing, a dangerous heeling angle may result or a capsizing accident. In this study, the heeling angle during turning was measured through experimentation with two training ships similar to passenger ships. These findings were compared with theoretical formulas for heeling angle when turning. We confirmed that the limit of the maximum heeling angle estimation using heeling angle formula when turning presented in IMO stability criteria. In addition, it was confirmed that the maximum estimated heeling angle can be reached by applying the result calculated in the theoretical formula 1.4 times when turning right and 1.1 times when turning left to reflect sailing speed when of rudder hard over. It is expected that this study will provide basis data for establishing safe operation standards for the prevention of dangerous heeling angles when turning.

• Journal of the Korean Institute of Navigation
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• v.7 no.1
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• pp.33-62
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• 1983

A navigator on bridge needs to know every kinds of motion characteristics of his vessel at sea. Generally when a vessel is completely built, the shipyard makes turning circle diagrams from the results of turing circle tests made during the sea trials for the reference of the vessel's owner. But referring only the data of a turning circle diagram, an officer on bridge can not figure out his vessel's maneuvering characteristics sufficiently, So nowadays the shipyard often adds Z test to turning circle test for more detail references. In this paper the author made Z and turning circle tests at the rudder angles of 15 and and 35 degress separately and in each of the case made a turrning circle diagram from the results of the turning circle test and the esults numerically calculated from mathematical formula made on the base of the maneuvering indices got from the Z test and compared them each other for the purpose of finding the correlations between them. Followings are concluded from the results. An actual turning circle diagram and a calculated one from the results of the Z test at same rudder angle coincides each other well when the center of the calculated circle is transferred by 1.7B toward the direction of the initial turning perpendicularly to the original course and 0.5L toward the direction in parallel with original course in case of the rudder angle of 35 degrees and 1.2B and 0.3L toward each of the above mentioned directions in case of rudder angle of 15 degrees.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.929-930
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• 2013

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.2
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• pp.111-118
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• 2006

It is indispensable to grasp the turning ability of a ship to operate her effectively. For this purpose, the author measured the turning ability of training ship, A-RA by use of bow thruster and stem rudder. The turning ability of this ship, in case of using both of stem rudder and bow thruster at the same time, caused by increase of steering angle provides more influence to the size of tactical diameter than it caused by the power of bow thruster. But the influence of bow thruster on the turning ability is available only within rudder angle $5^{\circ}\;-\;10^{\circ}$, so it is possible to grasp that the effect of bow truster is reduced as rudder angle become bigger. In case of the influence of bow thruster by her speed, the ability of bow thruster is very effective at low speed, but it is almost not available in normal turning speed. Therefore, the using both of stem rudder and bow thruster can be useful in case of low speed proceeding at entrance or departure of the narrow waterway or inside port which sea traffic is congest for collision avoidance.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.205-215
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• 2020

Objective: The purpose of this study was to investigate the relative angles and cross-correlation between body segments and ski among four alpine ski turning techniques. Method: 19 alpine ski instructors participated in this study. Each skier asked to perform 4- types of turning technique, classified by radius and level. 8 inertial measurement units were used to measure orientation angle of segment and ski on the anteroposterior and vertical axis. Results: Significant differences were found between types of turning in the segments-ski relative angle on the anteroposterior and vertical axis (p<.05). Although, cross-correlation showed a high correlation between angles of segment and ski, there were significant differences between types of turning. Conclusion: Based on our results, the relative movement and timing between each segment and ski is different according to the turning techniques, so the training methods should be applied differently.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2591-2596
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• 2007

The effect of incidence angle on the three-dimensional flow and aerodynamic loss in the downstream region of a high-turning turbine rotor blade has been investigated with a straight miniature five-hole probe. The incidence angle is changed to be +10, +5, 0, -10, -20, -30 and -40 degrees. The results show that the positive incidence reinforces the three-dimensional vortical flows within the turbine passage including the passage vortex, but the negative incidence weaken them significantly. A small increment in the positive incidence angle results in a remarkable aerodynamic loss increase, while increasing the incidence angle in the negative range leads to a very small change in the aerodynamic loss.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.25-31
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• 2004

Machinability in metal cutting processes depends on cutting input conditions such as cutting velocity, feed rate, depth of cut, types of work material and tool shape factors. In this study, to assess chip breaking characteristics of a turning process, an equivalent oblique cutting system to this has been established. And the equivalent effective rake angle was determined using side rake angle, back rake angle and side cutting edge angle of the tool. A non-dimensional parameter, Chip breaking index(CB), was used to assess Chip breaking characteristics of chip in conjunction with the equivalent effective rake angle. In case of positive rake angles of the equivalent effective rake, the back rake angle has little effect on the chip breaking characteristics however, in case of negative ones, the side rake angle has some effect on Chip breaking characteristics.

• Journal of the Ergonomics Society of Korea
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• v.30 no.2
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• pp.285-290
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• 2011

Due to the ageing-related degradation in physical and cognitive abilities, the elderly have difficulty in car driving and this is related to the high rate of car accidents among them. This study investigated the kinematic characteristics of old drivers' steering in right turning at intersections by comparing with young drivers. Thirteen old(60~70) and thirteen young(20~30) drivers who participated in the experiment turned their cars right side at intersections in a driving simulator. As results, the completion time of right turning at intersection of old drivers was larger than that of young drivers. The speeds of vehicle at the beginning and ending point of the right turning area of old drivers were smaller than those of young drivers, and also the steering angle at the ending point of the turning area of the former was smaller than that of the latter. The normalized jerk of old driver's steering was significantly larger than that of young drivers. These results indicate that old drivers modify their steering movement repeatedly and take the driving strategy of avoiding risks due to their reduced physical capabilities.

• Ocean Systems Engineering
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• v.10 no.1
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• pp.1-23
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• 2020

Hydrodynamic Drag of Surface combatants pose significant challenges with regard to fuel efficiency and exhaust emissions. Stern flaps have been used widely as an energy saving device, particularly by the US Navy (Hemanth et al. 2018a, Hemanth Kumar and Vijayakumar 2018b). In the present investigation the effect of flap turning angle on drag reduction is numerically and experimentally studied for a high-speed displacement surface combatant fitted with a stern flap in the Froude number range of 0.17-0.48. Parametric investigations are undertaken for constant chord length & span and varying turning angles of 5° 10° & 15°. Experimental resistance values in towing tank tests were validated with CFD. Investigations revealed that pressure increased as the flow velocity decreased with an increase in flap turning angle which was due to the centrifugal action of the flow caused by the induced concave curvature under the flap. There was no significant change in stern wave height but there was a gradual increase in the stern wave steepness with flap angle. Effective length of the vessel increased by lengthening of transom hollow. In low Froude number regime, flow was not influenced by flap curvature effects and pressure recovery was marginal. In the intermediate and high Froude number regimes pressure recovery increased with the flap turning angle and flow velocity.