• Korean Journal of Mathematics
• /
• 제8권1호
• /
• pp.27-32
• /
• 2000

In this paper, we show that for any continuous map $f$ of the circle $S^1$ to itself, (1) $x{\in}{\Omega}(f){\backslash}\overline{R(f)}$, then $x$ is not a turning point of $f$ and (2) if $P(f)$ is non-empty, then $R(f)$ is closed if and only if $AP(f)$ is closed.

• 한국항해항만학회지
• /
• 제45권6호
• /
• pp.298-305
• /
• 2021

자율운항선박(Maritime Autonomous Surface Ships, MASS)의 선회특성이 충돌회피에 미치는 영향을 식별하는 것은 MASS의 충돌회피에 핵심적인 단서를 제공할 수 있다. 본 연구의 목적은 다양한 타각과 선속에 의해서 변할 수 있는 선회특성이 충돌회피에 미치는 영향을 식별하기 위한 것이다. 선회특성이 충돌회피에 미치는 영향은 전장 161 미터 선박의 수학 모델을 이용하여 선회권을 관측한 후, 네 가지 충돌조우상황에 대한 충돌회피 수치 시뮬레이션의 결과를 이용하여 분석하였다. 두 선박 사이의 최소상대거리와 최소시간을 평가 변수로 이용하여 평가한 결과, 타각은 최소상대거리의 변화에 주요한 영향을 미치고, 선박의 속력은 최소시간의 변화에 주요한 영향을 미치는 것으로 나타났다. 본 연구에서 제안한 평가 방법은 MASS의 원격제어에서 충돌회피를 하나의 방법으로 적용 가능할 것으로 기대된다.

• 수산해양교육연구
• /
• 제21권1호
• /
• pp.59-67
• /
• 2009

It is necessary for navigator to understand sufficiently maneuverabilities based on experiences and the data which were gotten from several tests of the ship when he maneuver his vessel. By the way most navigators used to rely on his experiences or feelings only maneuvering ship. But when he encounters situations he did not experience before he may be in difficulties. So navigator must get both experiences and data based on experimental results. In this paper author performs several tests such as turning test, Zig-zag test and spiral test to provide informations of maneuverabilities for navigators. The obtained results are as follows: There occurs almost no difference in size of the turning circle by the changes of ship's speeds. The scale of the turning circle was decreased exponentially when the rudder angle was increased. The maneuverabilities is better turning to starboard side than to port side. Maneuverabilities are more effective when the rudder is used to small angle than to large angle. As a result of spiral test course stability was comparatively seemed to be good.

• 한국해양공학회지
• /
• 제31권5호
• /
• pp.335-339
• /
• 2017

This study investigated the sea trial performance of a wave piercing high speed planing hull (WPH). The bow shape of the boat is sharp, and it has no chine or spray strip like a normal planing boat. The skeg is attached to the bottom of the boat in the longitudinal direction from the bow to the stern. The speed performance was analyzed as the speed dropped in a wave, and the seakeeping performance was compared with that of a planing boat with a similar velocity coefficient by measuring the vertical acceleration of the bow in the wave. The turning circle was compared with Lewandowski's estimation for a planing boat. As a result of this study, it was confirmed that the velocity drop of the developed WPH was not large in a wave, and the vertical acceleration was greatly reduced compared with that of a normal planing boat. The turning circle was somewhat larger than the estimated results for a planing boat, but the overall tendency was the same.

• 수산해양기술연구
• /
• 제46권1호
• /
• pp.56-69
• /
• 2010

This study was intended to determine the maneuverability of the vessel CHARMBADA. When the rudder angle was at $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$, the maximum advance by slow, half and full ahead were varied in the range of 523.6-131.3m, 528.8-177.2m and 530.6-219.7m, respectively. The maximum transfer was 799.9-181.3m, 792.1-232.8m and 807.7-316.9m, respectively. The turning circle ability was better during starboard turning. When the rudder angle was $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$, variation in the maximum advances was 392.0m, 245.0m and 153.0m. The maximum transfer was 528.0m, 339.0m and 218.0m, respectively based on the regression equations. As the rudder angle became bigger, the maximum advance or maximum transfer became smaller by the exponential function. The advance inertia took 127sec, 145sec, 181sec each until the vessel speed was 7.0konts, 12.0konts, 17.0konts. The static inertia took 245sec, 269sec, 300sec each until the vessel speed was under 2.0konts and the advance distance was 114.4m, 181.2m, 197.0m each. Accordingly, the static inertia was inclined to increase to scale according to the increase in vessel speed. For the CHARMBADA, the smaller the rudder angle was, the much bigger the turning circle became due to adhesion to the skeg, thereby lowering the vessel's turning ability.

• 수산해양기술연구
• /
• 제22권2호
• /
• pp.22-30
• /
• 1986

It is very important for a navigator on bridge to know the maneuverability of his ship sufficiently at sea. Generally, the data of a turning circle test have long been used to study and evaluate the maneuverability of a ship. But referring only the data of the turning circle test method, he can not evaluate his ship's maneuvering characteristics sufficiently. So nowaday the test method added Z test to turning circle test for more detail references is considered to be desirable. In this paper, the authors performed PAL test and Z test together in order to study the maneuverability of M. S.Pusan 403, training ship of the National Fisheries University of Pusan. According to the results of PAL test, the rudder effect in port rudder angle of the M. S. Pusan 403 was found to be more effective than that in starboard one, because her changing amounts of angular velocity, turning radius and tangent speed in port rudder angles were found to be larger than those of them in starboard rudder one in unsymmetry. The relation between her drift angle(.8) and rudder angle (0) was found to be changing with .8=0.640 in direct proportion. As it appeared that her calculated K'-values were smaller than the standard K'-values of different kinds of ships in accordance with her Z test, her turning ability was found to be lower. The running distance of a turn in her 10$^{\circ}$ Z test was about 8.3 times her own length and was found not to be exceeded the standard maneuvering distance, therefore she was considered to have good maneuverabilities synthetically.

• 한국항해항만학회지
• /
• 제33권9호
• /
• pp.603-608
• /
• 2009

In this paper, a 3m-class free running model ship will be introduced with its manoeuvring performance experiments. The results of turning circle test and zig-zag test will be explained. The developed system are equipped with GPS, main control computer, wireless LAN, IMU (Inertial Measurement Unit), self-propulsion propeller and driving rudder. Its motion can be controlled by RC (Radio Control) and wireless LAN from land based center. Automatic navigation is also available by pre-programmed algorithm. The trajectory of navigation can be acquired by GPS and it provides us with important data for ship's motion control experiments. The results of manoeuvring performance experiment have shown that the developed free running model ship can be used to verify the test of turning circle and zig-zag. For next step, other experimental researches such as ship collision avoidance system and automatic berthing can be considered in the future.

• 제어로봇시스템학회논문지
• /
• 제11권4호
• /
• pp.363-368
• /
• 2005

This paper proposes an LOS(line-of-sight) guidance system of a ship for path following. From the viewpoint of a control configuration, guidance is a special type of compensation algorithm that is placed in front of the controller to accomplish navigational objects. A guidance system generates a reference trajectory for trajectory tracking or path control and decides the desired velocity, position and heading angle. A control system executes commands based on a reliable guidance law during navigation. An LOS vector from the vessel to a point on the path between two way-points in straight-line navigation or a point among turning circle in turning navigation is selected, and then a heading angle is calculated to converge the desired path based on the LOS vector. The LOS guidance law is defined for the straight-line and the turning circle, respectively. The effectiveness of the suggested LOS guidance system is assured through computer simulation.

• 수산해양기술연구
• /
• 제37권4호
• /
• pp.275-284
• /
• 2001

본 연구에서는 제주대학교 실습선 아라호(G/T : 990tons)의 조종 성능을 파악하기 위하여 2000년 8월과 2001년 5월에 2회에 걸쳐 제주항 북방 3마일 해상에서 조타에 의한 선회성과 추종성 등의 조종성능을 실시한 결과는 다음과 같다. 1. 부표 방위반법으로 측정한 선회권의 크기에서 선회종거는 우현선회시가 198m, 좌현선회시가 192m로서 좌현선회시가 우현선회시보다 6m 작았으며, 또한, 선회경의 크기는 우현선회시가 194m, 좌현선회시가 188m로서 좌현선회시가 우현선회시 보다 6m 작았다. 2. DGPS 측위에 의한 선회권의 크기에서 선회종거는 우현선회시가 196m, 좌현선회시가 194m로서 좌현선회시가 우현선회시보다 2m 작았다. 또한, 선회경의 크기는 우현선회시가 194m, 좌현선회시 190m로서 좌현선회시가 우현선회시보다 4m 작았다. 3. 신조 시운전시 부표 방위반법에 의해 측정한 선회권의 크기와 2001년 5월에 DGPS 측위에 의하여 측정한 선회권의 크기를 비교해 본 결과, 선회종거는 DGPS 측위에 의한 선회권이 신조시운전시 선회종거보다 우현선회시가 1m 컸으며, 좌현선회시가 21m 작았다. 또한, 선회경의 크기는 우현선회시 16m, 좌현선회시 23m 작았다. 4. 선속 13k't로 전속 전진중 타각 $35^\circ$로 좌현 또는 우현으로 전타 했을 때 선회각 $180^\circ$에서 선속이 7.8k't이고 $360^\circ$선회시는 6.0k't가 되었으며, 소요 시간은 좌현선회시가 150초, 우현선회시가 156sec로 좌현선회시가 우현선회시보다 6초 짧았으며, 선회평균 각속도는 좌현선회시가 $2.4^\circ$/sec, 우현선회시가 $2.3^\circ$/sec였다. 5. 타각 $10^\circ$, $20^\circ$, $30^\circ$ Z시험에서 선회성지수 K와 추종성지수 T는 각 각 선회성지수는 1.24, 1.45, 1.65였으며, 추종성지수는 각 각 0.33, 0.20, 0.14가 되어 $30^\circ$인 경우가 $10^\circ$, $20^\circ$ Z시험에서 보다 선회성지수 K는 크고, 추종성지수 T는 작아서 대각도 조타일 때가 소각도 조타일 때 보다 조종성능이 양호하였다.

• 수산해양기술연구
• /
• 제51권2호
• /
• pp.245-256
• /
• 2015

This study is intended to provide navigator with specific information necessary to assist the avoidance of collision and the operation of ships to evaluate the maneuverability of dead weight tonnage 8,000 tons Oil/Chemical tanker. The actual maneuvering characteristics of ship can be adequately judged from the results of typical ship trials. Author carried out sea trials based full scale for turning test in ballast condition and full load condition, semi balanced rudder and flap rudder. The turning circle maneuvering were performed on the starboard and port sides with $35^{\circ}$ rudder angle at the normal continuous rating. The results from tests could be compared directly with the standards of maneuverability of IMO and consequently the maneuvering qualities of the ship is full satisfied with its.