• 대한조선학회지
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• 제3권1호
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• pp.25-32
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• 1966

For preliminary estimation of ships' machinery weights, many papers giving well-judged data and discussions for rational method of estimation, such as [1], [2], [3], [4], [5], [6], are available, however, they are mostly concerned with large ships propelled by power more than about 2, 000 horsepower. Regarding the medium and small-sized ships, as far as the author is aware, fragmental data and vague discussions found in various technical literature are the all available. In this paper, available data concerned with machinery weights of commercial ships propelled by direct-drive diesel plants of power below 3, 000 horsepower with single screw propeller are collected and analysed to obtain systematic data Fig. 1 and Fig. 2 as weight to power ratio versus power per shaft diagrams together with suplementary data Fig. 1 and Fig. 3. Influences of various factor such as revolutions per minute, mean effective pressure, type and construction of the main units on machinery weights are also investigated in detail to give a better guidance for logical and rational utlization of the proposed diagrams in preliminary estimation of machinery weights.

• 동력기계공학회지
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• 제9권4호
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• pp.24-30
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• 2005

For a reciprocating compressor of household refrigerators, a direct analogy between the pipe flow network and the electric circuit network has been utilized to set up a mathematical model for oil supply system. Individual lubrication elements of the oil supply system, such as propeller- installed oil cap, oil galleries, radial oil feeding holes, spiral oil grooves, and various sliding surfaces have been analogized by equivalent electric elements, and these have been combined together to form an electric circuit corresponding to the whole oil supply system. By solving the closed network equations of the model, oil flow rates at various lubrication elements could be obtained. Total amount of the oil flow rate drawn into the shaft has been measured and compared reasonably well with the prediction of the numerical simulation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.463-468
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• 2011

The prospect of Arctic trade transportation opening on a year-round basis creates a vast opportunity of exploring untapped resources and shortened navigational routes. However, the environment's remoteness and lack of technical experiences remains a big challenge for the maritime industry. With this, engine designers and makers are continually investigating, specifically optimizing propulsion shafting system design, to meet the environmental and technical challenges of the region. Further, classification societies recognize the need to upgrade the Unified Rules concerning elements to meet current Polar requirements. Hence in this paper, excitation torque calculation on Polar class vessels propulsion shafting system will be reviewed. The propeller - ice interaction load effect, which is a main consideration of excitation source of Polar Class propulsion shafting system, on shaft design calculation will be analyzed.

• 한국정밀공학회지
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• 제13권3호
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• pp.132-140
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• 1996

This paper developes a torsional vibration model of heavy duty truck drive line for simulation of a driving rattle, which causes very annoying noise to driver at the full load driving condition. Test results show a peak in the fit plots at the frequency of the 2nd harmonics of propeller shaft revolution. A 10 d.o.f. lumped parameter nonlinear torsional vibration model is constructed and engine torque variation is calculated from P- .theta. diagram. Time responses are simulated and compared with the test results, which show fairly good agreement. The effects of paramenter change are investigated, and the optimum configuration is proposed.

• 한국산학기술학회논문지
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• 제18권9호
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• pp.480-485
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• 2017

저널 베어링인 선미관 후부 베어링의 후방부에 발생하는 발열 사고는 프로펠러 하중이 추진축을 처지게 하여 후방부에 과도한 국부압착압력이 작용하는 것이 주된 원인이다. 선미관 베어링의 라이닝 재료로 사용되는 화이트 메탈보다 영률이 훨씬 작은 재료를 사용한다면 축과의 접촉 면적을 크게 함으로써 발열 사고의 원인이 되는 국부압착압력의 저감이 가능할 것이다. 본 연구의 목적은 영률이 작은 재료로 만들어진 베어링 제품의 적용에 앞서, 축계 해석을 통해 새로운 제품 적용시의 압착압력 분포특성을 파악하고 허용 압력을 결정하는데 있다. 국부압착압력의 계산에 있어서는 접촉 너비를 따라 반 타원형상의 압력 분포를 가정한 Hertzian 접촉 조건을 도입하였으며, 엔진 가동 상태의 프로펠러 하중, 열 효과 및 선체 변형을 고려하였다. 해석 결과를 통해 영률이 작은 제품은 기존 제품을 적용한 실적선에 비해 국부압착압력의 상당한 저감이 가능함을 확인하였고, 또한 하중 조건이 바뀌더라도 압력 분포의 변화가 작아 강건 설계가 가능한 장점이 있음을 알 수 있었다. 본 연구를 통해 제시되는 제품의 성능 사양을 제조사가 보장한다면 영률이 작은 제품의 적용이 가능하리라 판단된다.

• 대한조선학회논문집
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• 제53권6호
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• pp.494-502
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• 2016

The accurate assessment of hull-appendage interaction in the early design stage is important to control the inflow to the propeller plane, which can cause undesirable hydrodynamic effects in terms of cavitation phenomenon. This paper describes a numerical analysis for the flow around a fully appended surface ship model for which KRISO has carried out a model test in the Large Cavitation Tunnel(LCT). This numerical study was performed with the LCT model test in a complementary manner for a good reproduction of the wake distribution of surface ships. A second order accurate finite volume method provided by a commercial computational fluid dynamics(CFD) program was used to solve the governing Reynolds Averaged Navier-Stokes(RANS) equations, where the SST $k-{\omega}$ model was used for turbulence closure. The numerical results were compared to available LCT experimental data for validation. The calculations gave good predictions for the boundary layer profiles on the walls of the empty cavitation tunnel and the wake at the propeller plane of the fully appended hull model in the LCT.

• 인터넷정보학회논문지
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• 제22권3호
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• pp.67-73
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• 2021

본 논문에서는 드론의 추락을 예방하기 위해 드론의 프로펠러와 연결된 모터로부터 진동 데이터를 수집하고 순환 신경망(recurrent neural network, RNN)과 long short term memory (LSTM)을 사용하여 드론의 비정상 진동을 예측하는 연구를 진행하였다. 드론의 비정상 진동 데이터를 수집하기 위해 드론의 프로펠러와 연결된 모터에 진동 센서를 부착하여 정상, 바(bar) 손상, 로터(rotor) 손상, 축 휨에 대한 진동 데이터를 수집하고 LSTM과 RNN을 통해 비정상 진동을 예측한 결과의 평균 제곱근 오차 (root mean square error, RMSE) 값을 비교분석 하였다. 시뮬레이션 비교 결과, RNN과 LSTM을 통해 예측한 결과 모두 비정상 진동 패턴을 매우 정확하게 예측하는 것을 확인하였으며 LSTM을 통해 예측한 진동이 RNN을 통해 예측한 진동보다 RMSE값이 평균 15.4% 낮은 것을 확인하였다.

• 한국음향학회지
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• 제29권2호
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• pp.118-124
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• 2010

본 논문에서는 차량 구동라인의 굽힘 진동을 저감시키기 위해 사용되는 동흡진기의 설계 파라미터에 대한 최적설계를 수행하였다. 정확한 동적 응답특성을 얻기 위해 구동라인을 구성하는 추진축의 진동해석으로부터 추출된 유연성 데이터를 구동라인 동역학 모델에 적용하여 유연체 구동라인을 만들었다. 동흡진기의 내부 튜브 질량, 고무 강성계수 및 고무 감쇠계수를 최적화를 위한 설계 파라미터로 선택하였다. 구동라인의 수직 가속도를 최소화시키기 위해 중심합성 실험계획법의 3-요인, 2-수준 실험을 15회 수행하여 목적함수에 대한 2차 회귀방정식을 만들었으며, 최적화 프로그램을 이용하여 동흡진기 설계 파라미터들을 결정하였다. 최적화된 동흡진기를 장착한 차량 모델은 초기 모델에 비해 구동라인의 수직 가속도 피크값을 17.1% 감소시켰다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권4호
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• pp.351-372
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• 2017

Propulsion in waves is a complex physical process that involves interactions between a hull, a propeller, a shaft and a prime mover which is often a diesel engine. Among the relevant components, the diesel engine plays an important role in the overall system dynamics. Therefore, using a proper model for the diesel engine is essential to achieve the reasonable accuracy of the transient simulation of the entire system. In this paper, a simulation model of a propulsion system in waves is presented with emphasis on modeling a two-stroke marine diesel engine: the framework for building such a model and its mathematical descriptions. The models are validated against available measurement data, and a sensitivity analysis for the transient performance of the diesel engine is carried out. Finally, the results of the system simulations under various wave conditions are analyzed to understand the physical processes and compare the efficiency for different cases.

• Journal of Advanced Marine Engineering and Technology
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• 제39권2호
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• pp.143-151
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• 2015

Recently, tidal current energy conversion is a promising way to harness the power of tides in order to meet the growing demands of energy utilization. A new concept of tidal current energy conversion device, named Vane Tidal Turbine (VTT), is introduced in this study. VTT has several special features that are potentially more advantageous than the conventional tidal turbines, such as propeller type tidal turbines. The purpose of this study on VTT is to analyze the possibility of extracting the hydrokinetic energy of tidal current and converting it into electricity, and evaluate the performance of turbines for various numbers of blades (six, eight and twelve) using Computational Fluid Dynamics (CFD). At various tip-speed ratios (TSR), the six-bladed turbine obtains the highest power and torque coefficients, power efficiency is up to 28% at TSR = 1.89. Otherwise, the twelve blade design captures the smallest portion of available tidal current energy at all TSRs. However, by adding more blades, torque extracted from the rotor shaft of twelve-bladed turbine is more uniform due to the less interrupted generation of force for a period of time (one revolution).