• Journal of Ocean Engineering and Technology
• /
• v.16 no.6
• /
• pp.25-31
• /
• 2002

A system identification method is introduced to increase the prediction accuracy of a ship's maneuverability in PMM test, analysis. To improve the accuracy of linear hydrodynamic coefficients, the analysis techniques of pure sway and yaw tests are developed, and confirmed. In the analysis of sway tests, accuracy to linear hydrodynamic coefficients depends on the frequency of sway motion. To obtain nonlinear hydrodynamic coefficients for large drift angles, a combined yaw test is introduced. Using this system identification method, runs of PMM test can be reduced while retaining sufficient accuracy, compared to the Fourier integration method. Through the comparisons with sea trial results and the Fourier integration method, the accuracy and efficiency of the newly proposed system identification method, based on least square method, has been validated.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1993-1998
• /
• 2004

The present study was carried out to develop highly efficient RC ornithopter 'Songgolmae' powered by motor and battery. Designed electric ornithopter weighs 277 grams and has 3 channels radio control. 1t runs on an electric motor by a lithium polymer battery and has a gear ratio of about $75{\sim}95$ to 1 to flap its 88 cm wingspan. The aerodynamic performance of the ornithopter, applied to a flapping motion only, was validated by flight tests. Flight times have exceeded 23 minutes until the battery was used up. The flight test results indicate that the ornithopter developed here has sufficient thrust to propel itself in a forward flight. From the economical point of view and the handling of the RC ornithopter, it can be said that the developed robot ornithopter is an effective RC ornithopter. This radio controlled ornithopter flies its way high into the sky just like a real bird flies.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.06a
• /
• pp.25-26
• /
• 2013

제한수역에서 측벽부근을 대형선박이 항행할 경우, 측벽으로 인하여 발생하는 유체력이 대형선박의 조종운동에 상당히 크게 영향을 미친다는 것은 잘 알려져 있다. 이 논문에서는 방파제형상을 하고 있는 측벽 부근을 대형선박이 항행하는 경우, 선박과 방파제 형상간의 간섭력 추정을 위해 세장체 이론을 토대로 한 계산 방법을 적용하였으며, 선박에 미치는 측벽의 영향을 파악하기 위하여 방파제길이, 방파제와 선박간의 거리 및 수심을 변수로 하여 선박과 측벽과의 간섭력을 수치 계산하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1996.09a
• /
• pp.81-88
• /
• 1996

Mathematical model of maneuvering motion for a single-screw single-rudder ship is established and several applications to the special situations of maneuvering are attempted. While the mathematical model for twin-screw twin-rudder ship is not studied presented so much because that type of ship is not popular. Lee et al. have examined the characteristics of such ship by captive model tests in 1988 in Japan. This paper proposes new mathematical models for propeller effective wake (1-wp) and effective neutral rudder angle $\delta$R in the case of twin-screw twin-rudder ship. And some maneuvering motions are calculated with proposed models and compared with exact simulations.

• Journal of the Korean Institute of Navigation
• /
• v.4 no.1
• /
• pp.51-61
• /
• 1980

In order to evaluate rolling characteristics of high speed container carrier the author developed yaw-sway-rudder coupled rool equation, which is likely to be 5th order differential equation. The free rolling time history with particular reference to automatic steering, was computed upon the base of the yaw-sway-rudder coupled roll equation. The computed result explained effects of $C_1$ and $C_2$ on rolling behaviors and furthermore the effect of $C_2$ proved to be very effective where $C_1$ and $C_2$ are yaw gin constant and yaw-rate gain constant of auto-pilot respectively. Computation was carried out using Matsumoto's data of hydrodynamic force derivatives of 5 meter long container model.

• Journal of the Korean Institute of Navigation
• /
• v.18 no.4
• /
• pp.11-21
• /
• 1994

Final aim of this paper is a study on simulation of automatic steering of a ship in random seas. In order to achieve this aim, we need excitation due to random seas. The excitation may be estimated from energy spectrum of irregular waves and response functions of manoeuvring motion of a ship in regular waves. This paper deals with response functions of manoeuvring motion of a ship in regular waves. We discussed New Strip Method(NSM) of sway-yaw-roll coupled motions in regular waves. NSM is defined in space axes system and that has been used to predict seakeeping performance of a ship in waves. But ship manoeuvring is defined in body fixed axes system. So we cannot use NSM theory itself in predicting manoeuvring performance of a ship in waves. We introduced relationship between space axes system and body fixed axes system. And we developed modified NSM which was defined in body fixed axes system and was able to be used in manoeuvring motion of a ship in waves. We calculated sway and yaw response functions of manoeuvring motion of a bulk carrier in regular waves.

• Journal of the HCI Society of Korea
• /
• v.9 no.2
• /
• pp.13-21
• /
• 2014

Jump-rope is a simple and effective exercise, but its intensive exercise load and monotonous pattern make it difficult to perform consistent workout. On the other hand, jumping rope accompanies large amount of kinetic energy which can be converted into electrical energy. In this study, we designed and implemented a self-powered jump-rope which can support the low-power embedded Bluetooth system inside it. The embedded system wirelessly transmits the acceleration data measured during jumping-rope exercise to a smartphone. We also developed a smartphone app which can count the number of jumps and provide real-time feedback with sound and animated graphic effects in a game context. Pilot test using the prototype smart jump-rope verified that it can be useful to motivation for the jump-rope exercise and make the exercise more effective by providing users with precise information about their exercise. We expect that the developed self-powered jump-rope will change the exercise from an intensive physical activity into electricity-generating fun experience combined with smartphone game, which maximize the benefit of the consistent jump-rope exercise.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2014.10a
• /
• pp.15-16
• /
• 2014

제한수역에서 측벽부근을 항행하는 대형선박에 미치는 측벽영향은 대단히 크고, 선박조종운동의 관점에서 보았을 때 상당히 중요한 문제이다. 이 연구에서는 측벽의 길이를 변화시키면서 측벽과 선박과의 종방향 및 횡방향 거리, 측벽의 길이 및 수심에 따른 측벽영향에 대하여 수치 계산하였다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.1
• /
• pp.67-75
• /
• 2023

In this study, the dynamic characteristics of an offshore platform being installed and physical phenomena are analyzed from the perspective of interaction between operation and maneuvering simulation using a real-time Maneuvering & Operation simulator of Shipbuilding & Marine Simulation Center at Tongmyong University. It was simulated to install the semi-submersible drilling rig moored by 8 mooring lines according to a scenario that is similar to it on the real sea, and 4 tug boats for position keeping of the rig and an offshore support vessel for hook-up of the mooring lines were operated. During the simulation, the motion, trajectory, tension of the objects were output in real time, and they were analyzed at each work procedure. This study about the simultaneous simulation of operation and maneuvering showed the detailed motion of the offshore platform and ships on the operation procedure and the interaction between operation and maneuvering in specific environment condition. Also, it confirmed that the simulation can be utilized to determine the possibility of offshore platform installation in specific situations.

• The Journal of Internal Korean Medicine
• /
• v.26 no.4
• /
• pp.761-766
• /
• 2005

Objectives : 본 연구는 암환자의 위장관 기능장애를 개선시킬수 있는 보다 효과적인 약물개발의 일환으로 곽향 추출물의 장운동에 미치는 영향을 평가하기 위해 수행되어졌다. Methods : 생리적인 상태에서 곽향추출물이 장운동에 미치는 영향을 알아보기 위해 장운동촉진제인 carbachol과 곽향추출물을 실험쥐들에게 투여후 15분후 charcoal meal을 먹여서 charcoal meal의 소장내 통과 정도를 비교 측정하였다. 또, loperamide, scopolamine, nicotine으로 장운동을 억제시켜 놓은 실험쥐들에 15분 간격으로 곽향 추출물과 charcoal meal을 먹인 후 역시 charcoal meal의 소장내 통과 정도를 비교 측정하였다. Results : 곽향 추출물은 생리상태에서는 장운동에 영향을 미치지 않았다. 곽향추출물은 loperamide와 scopolamine으로 유발된 장운동 억제상태에 대하여 부분적으로 영향을 끼쳤다. 그러나 nicotine으로 유발된 상태에 대해서는 영항을 끼치지 않았다. Conclusion : 곽향 추출물은 소화관 기능부전 완화에 효과적으로 작용하는 천연물이라 추론할 수 있다.