• Proceedings of the Korean Society of Computer Information Conference
• /
• 2018.07a
• /
• pp.355-356
• /
• 2018

본 연구에서는 드론 기술을 응용한 부력조형물의 수평 및 수직 자세제어에 관한 연구를 수행 하였다. 기존의 공중부양 조형물은 헬륨 Gas를 이용한 애드벌룬이 대표적으로 로프를 이용한 단순한 공중부양 조형물이었다. 본 연구에서는 이러한 공중부양 조형물에 로프를 없애고 드론 기술을 응용한 프로펠러로 공중부양 조형물의 자세를 제어하는 방법을 연구하였다. 시스템 구성은 단일 제어기로서의 역할보다 시스템 구성요소로서의 역할이 매우 중요해지므로 조형물의 제어시스템, 다양한 센서등의 연동되어지는 전체의 제어기로 확장시켜 사용되는 퓨전 시스템의 방향으로 구성하였다. 부력조형물의 수평 및 수직제어를 위하여 사용된 센서는 2축의 자이로센서와 3축의 가속도센서를 사용하였다. 프로펠러와 연결된 BLDC모터를 효율적으로 제어하기 위한 알고리즘으로 PI 알고리즘을 이용하였다. 시스템의 성능 향상을 위한 효율적인 동적 작업부하 균등화와 시스템 자원인 CPU와 메모리를 효율적으로 사용하여 고성능 컴퓨팅 시스템의 처리량을 최소화하고, 센싱 및 제어의 수행시간을 최소화하였다. 본 연구에서는 PI 알고리즘을 시스템에 적용하여 응답특성 실험을 행한 결과 시뮬레이션에 의한 응답 결과와 잘 일치하였으며 그 유용성이 검증하였다.

• Journal of Korea Ship Safrty Technology Authority
• /
• s.24
• /
• pp.4-20
• /
• 2008

Stainless steel 304 or stainless steel 630 types using propeller shaft of a small ship or a FRP fishing boat generally restrain localization corrosion and abrasion damage occurrence to shaft bearing or grand packing contact. In general, the residual stress which remains after welding or heat treatment in material can cause the stress concentration or localization corrosion. In case of small ship, stainless steel such as STS304 has long been used for propeller shaft. Meanwhile, crew of small ship tend to reuse damaged propeller shaft after repair by welding and performing heat treatment to save cost. However, it was found that reused propeller shaft by repair often caused troubles in ship's operation. In this study, the basic guideline for maintenance and treatment of propeller shaft are investigated. From the results of investigation, remarkable deterioration of the material properties and corrosion resistance on the welded work part was observed.

• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.1
• /
• pp.26-39
• /
• 2000

This paper presents the influence of Reynolds number on propeller open-water performance at the towing tank and the cavitation tunnel for series propellers(No. of blade=4, $0.3{\leq}A_E/A_O{\leq}0.75,\;0.5{\leq}P/D{\leq}1.1$). It is shown that the Reynolds number recommanded by 15th and 17th ITTC is not large enough to obtain reliable P.O.W. test results and then the suitable test conditions for the both facilities is suggested. The correlation of the propeller open-water characteristics at the cavitation tunnel and the towing tank is described and a correlation factor $\kappa$ is deduced from those test results. The viscous effect of the flow around the propeller shaft on the propeller characteristics is investigated from the velocity measurement by Laser Doppler Velocitimetry(L.D.V.). The measured velocity distribution shows that viscous flow effect is not negligible.

• Journal of Aerospace System Engineering
• /
• v.16 no.6
• /
• pp.54-63
• /
• 2022

Recently, electric propulsion aircraft with various propeller mounting positions have been under construction. The position of the propeller relative to the wing can significantly affect the aerodynamic performance of the aircraft. Placing the propeller in front of the wing produces a complex swirl flow behind or around the propeller. The up/downwash induced by the swirl flow can alter the wing's local effective angle of attack, causing a change in the aerodynamic load distribution across the wing's spanwise direction. This study investigated the influence of the distance between a propeller and a wing on the aerodynamic loads on the wing. The swirl flow generated by the propeller was modelled using an actuator disk theory, and the wing's aerodynamics were analysed with the VSPAERO tool. Results of the study were compared to wind tunnel test data and established that both axial and spanwise distance between the propeller and the wing positively affect the wing's lift-to-drag ratio. Specifically, it was observed that the lift-to-drag ratio increases when the propeller is positioned higher than the wing.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.10
• /
• pp.270-276
• /
• 2019

According to the International Maritime Organization (IMO) 2020 Regulation, ships operating outside designated emission control areas (ECA) have to use low-sulfur oil with a sulfur content of 0.5% or less by January 2020. To minimize the consumption of high-priced low-sulfur oil, it is urgent to introduce efficient energy-saving devices (ESD), and contra-rotating propeller (CRP) systems are well known to be the most effective one. The shafting system that drives a CRP is composed of an inner shaft and an outer one and has a mutually influential system that is much more complex and heavier than a general shafting system. An initial design was carried out to install a CRP system for the first time in Korea. The purpose of this study is to verify whether the journal bearing meets the classification's design criteria through a bearing reaction force analysis for the classification's approval of the initial design. It is ideal for the thrust of the propeller to act on the center of the shaft, but thrust eccentricity occurs due to the uneven wake caused by the stern shape. Load conditions were applied while considering thrust eccentricity to perform the shaft analysis, and the results were compared with the classification's criteria.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.2
• /
• pp.81-89
• /
• 2019

In this study, wind tunnel test on Quad-Tilt Propeller which has tandem wings is carried out to analyze the aerodynamic interference effect of front wing and propeller on rear wing during forward flight. Using 6-axis balance system, forces and moments of whole aircraft were measured and using strain gauge at wing root, bending moments were measured to observe change of aerodynamic force of each wings. A 12-hole probe was used to measure the flow field in the wing and propeller wake. Flow characteristics were observed qualitatively through flow visualization experiment using tuft and smoke. To measure the aerodynamic interference by elements, the influence of front wing and propeller on rear wing was analyzed by changing the wings and propellers mount combination.

• Journal of the KSME
• /
• v.53 no.2
• /
• pp.30-34
• /
• 2013

기어는 사람에 의해 사용된 가장 중요한 기계 중의 하나이며, 회전하는 두 축 사이에 운동과 동력을 전달하고 회전 방향과 속도를 변경하는 역할을 한다. 기어는 우리가 손에 차는 시계나 벽시계뿐만 아니라 자동차, 기차, 선박, 비행기에서 엔진의 동력을 전달하여 바퀴나 혹은 프로펠러를 돌리기 위해 사용된다. 또한 장난감, 복사기, 팩스, 풍력발전기에 사용하는 등 그 용도가 다양하다. 이 글에서는 기어의 역사를 간단히 살펴보고 기어의 진동 소음에 관련된 연구 주제에 대해 기술한다.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.311-312
• /
• 2006

선박의 추진축은 선박의 기관실 최말단부에서 바깥의 프로펠러까지 선체를 관통하여 설치되고 회전하기 때문에 선외로부터의 해수유입을 쳐대한 차단하는 역할을 하는 독특한 메커니즘을 가진 축밀봉장치(Shaft Sealing System)를 필요로 하는데 이것을 스턴튜브 씰(Stem Tube Seal)이라고 한다. 본 연구는 국내 중소형 선사들이 저렴한 가격대비 우수 품질의 씰 및 하우징을 사용할 수 있고 3차원 형상화를 통하여 선박의 운용자가 쉽고 정확하게 스턴튜브 씰을 이해 및 신속 정비가능, 해외업체 생산 규격을 선박 축에 맞게 절단, 접합의 씰 성능저하 관행을 고쳐 선주가 원하는 사양과 규격대로 제작된 우수한 씰 제품을 공급할 수 있고, 선박용 기자재에 대한 기초지식, 씰링 메카니즘, 구조 및 유동 해석 결과를 제공하여 국내 최초의 무접착 원형 메인 씰 개발 및 씰 하우징 제작 및 독자설계 기술을 확립하고자 한다.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.6
• /
• pp.518-526
• /
• 2018

As a new technical approach, this paper introduces a method for improving an electrically propelled outboard motor in consideration of the driving system applied to an electric-propulsion boat with solar cell energy. The most efficient model for a drive shaft, propeller shaft, and bevel gear was suggested and examined with respect to the results of test operation in prototype mode. Furthermore, this research included a performance evaluation of the manufactured prototype to acquire the purposed quantity value and the development items. After manufacturing the desired prototype of an electrically propelled outboard motor, the maximum sail time, thrust force, noise, and weight were evaluated in a performance test. An additional test in relation to the maximum sail speed (knots) of the completed prototype was conducted using a sea trial evaluation to acquire the optimum quantity.

• Journal of Ocean Engineering and Technology
• /
• v.12 no.1
• /
• pp.23-31
• /
• 1998

Kind 1 propeller shaft in ships is the shaft which is provided with effective measures against corrosion by sea water, or the shaft which is made of approved corrosion resistance materials. The propeller shaft other than specified above is Kind 2. Thus, this study is mainly concerned with the resistance to fatigue damage in sea water against stress concentrations due to the notches. The results obtained can be summarized as follows; (1) The stress increases with curing time, however, when the curing time reaches at 96 hours the stress becomes a constant value. The elongation decreases with curing time, however, when the curing time reaches at 48 hours the elongation becomes a constant value. Thus, in case of FRP coating on propeller shaft, it is necessary to cure for 48 hours at least. (2) The relation of $\sigma$$_n$-K$_t$ is to be classified into two parts, which is a part where fracture nominal stress, $\sigma$$_n$, decreases with increasing $K_t$, and a part where $\sigma$$_n$ is nearly constant independent of $K_t$. (3) According to a linear notch mechanics, the measure of severity controlling the fracture in notched FRP body is the notch root radius, $\rho$. The notched static strength of an arbitrary specimen will be estimated from $\sigma$$_{max}$ -1/$\rho$ curve. (4) Through the observation of cross section after fatigue test, the part of interface was kept good condition irrespective of loading conditions.