• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.135-140
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• 2022

Most machines are made of several types of . In particular, the shaft system of the ship consists of the brass of the propeller blade and the stainless steel of the shaft. When dissimilar the electrolyte solution of seawater, a voltaic cell and a shaft electromotive force is generated. This electromotive force causes electrical corrosion of the bearing and shaft supporting the shaft system. prevent this corrosion, a shaft grounding system is installed in ships. As for the experimental method, various information acquired by designing a program to periodically measure the electromotive force of the controllable pitchpropeller) system using an A/D converter of NI. This study analyzed the generation and characteristics of accumulator electromotive force for CPP and considered the installation location of the grounding system to remove the accumulator electromotive force.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.803-809
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• 2018

Generally, the gap-and-sag method is used in the shipbuilding stage before coupling the shafts to check whether they are installed at the same position as designed and derived from shaft alignment calculation. The primary installed propeller shaft becomes a reference point, the position of the remaining shafts are sequentially determined through the gap-and-sag value derived from the deflection and deflection angle at each shaft flange by own weight. If the reference point varies against the design value, it would have a series of effects on the installation of the remaining shafts. Moreover, after coupling the shafts, even if the bearing reaction forces derived from measurement are satisfied by the allowable limit range, consequently it might have an adverse effect on the stability of the shafting system by not being able to estimate the relative slope angle between the propeller shaft and the after-stern tube bearing. In this paper, to deal with above-mentioned phenomenon, the theoretical calculations related to designing an effective support point of the aft stern tube bearing and analysis by measurement is conducted through a case of open-up inspections. Based on this, a shaft installation guideline is proposed to minimize the misalignment related to preventing wiping damage of the after-stern tube bearing.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.2
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• pp.51-62
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• 1998

In this paper, a CAD/CAM system for 5-axis machining of model propeller is introduced. This system has been developed under the environment of personal computer and Windows NT. In order to enhance the productivity, existing text-based design S/W was integrated into this graphic-based system. Non-Uniform Rational B-Spline method is used to represent the sculptured surface of propeller blades and hub using point data, and surface blending between blade and hub is realized in this system. For 5-axis machining of sculptured surface, tool/work collision and interference are checked and inverse kinematic analysis is performed to make NC data. In addition, tool and workpiece are animated on the PC monitor by preparing NC verification module. Finally, optimal cutting conditions are determined empirically and those cutting conditions are integrated into this S/W so that the whole process from design to machining can be done automatically.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.264-272
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• 2011

Shipbuilders carry out the operation test to check the conditions of the main propulsion system and auxiliaries for moored vessel in the quoy before the sea trial. The estimation of the thrust and torque for the partially submerged propeller should be prepared to ensure the safety of mooring line and the ship. In this paper, the variations of the thrust and torque according to the shaft submergence and the propeller rotating speed in bollard pull condition are investigated with the model test and the numerical analysis. Based on these resaearch, the empirical formula representing the physical phenomena of the partially submerged propeller is derived and validated through comparison to measurement results of full-scale propellers under the quoy operation test.

• CDE review
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• v.2 no.2
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• pp.50-51
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• 1996

본 과제에서는 point data를 사용하여 CAD에서 모델링된 프로펠러를 LOM 공정으로 제작한 후 LOM 모델을 master pattern으로 사용하여 주조까지 실행하는 작업을 실시하였다. 주조공정시 알루미늄을 소재로 사용하였으며, 주조된 프로펠러는 기능테스트에 사용할 수 있는 성능을 지니고 있다. 이 결과는 현재까지 프로펠러 제작용으로 주로 사용하던 5축 가공을 rapid prototyping과 주조방법을 통해 대처할 수 있는 가능성을 제시하고 있다. 그러나 아직 제품의 정확도가 부족하여 오차 발생원인 및 누적과정을 분석하여 정확도를 향상시키는 작업이 향후 연구과제로 남아있다. 본 연구는 현재 수행중인 국제공동과제 "동시공학 구현을 위한 형상설계 및 급속조형 기술 개발"의 일부이며 알피 코리아사와 삼성중공업의 기술적 도움으로 진행되었다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.119-125
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• 2007

In recent days, the consumption of stainless steel in the propulsion shafting systems for small-medium class vessel is increased due to its high corrosion protection with wear resistant properties. Unfortunately the small and medium class vessel that operated in the west-south sea area of Korean peninsula experienced heavy wear down due to the role of mud. In the event of wear or broken down, the propeller shaft must be replaced by new one, but the new shaft is very expensive and time-consuming for order made supply. In this case, the methods of built up for wear and broken shaft by welding is one of the most effective cases. In this study, the built up welding for austenitic stainless steel shaft has been accomplished by various pre-surface treatment, welding methods, post heattreatment and inspection. The results confirmed that the built-up welding was one of the effective methods for stainless steel shafting.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.163-167
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• 1990

이 논문에서는 기구학적 특성을 고려, 크랭크 축과 프로펠러 축의 비틈 진동 의 주요 발생 Mechanism에 관하여 요약하고, 발생된 진동 및 소음을 감소시 키기 위한 방법을 저자의 연구수행 결과의 일부와 비교한다[1,2].

• Journal of the Society of Naval Architects of Korea
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• v.39 no.3
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• pp.41-47
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• 2002

Turbulent wake behind a ship propeller has been investigated using the adaptive hybrid 2-frame PTV(Particle Tracking Velocimetry). 400 instantaneous velocity fields were measured according to 4 different blade phases and ensemble-averaged to investigate the spatial evolution of the vortical structure of near wake within one propeller diameter downstream. The phase averaged mean velocity fields show the potential wake and the viscous wake formed by the boundary layers developed on the blade surfaces. As the tip vortex evolves downstream, the slipstream is contracted and the turbulent intensity is decreased with viscous dissipation and turbulent diffusion.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.2
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• pp.219-224
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• 1998

Recently to achieve the anti-corrossive effect in propeller shafts the coating technique with suit-able coating materials is available instead of bronze-sleeved shafts. In this case the coating mate-rials in service must not be delaminated from the shaft and the crack must not be originated. Thus the various performance and security test for coating materials of propeller shaft must be carried out under the real conditions or more severe circumstance. The most important factors effecting on the funtion of coating materials in propeller shaft are the strain and the environment of sea water. In this paper therefore the maximum possible strain which can be occured in real propeller shaft was calculated based on IACA standard classification rule in order to give the proper level of strain to the test samples in performance test of propeller shaft coating materials.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.189-196
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• 2018

Propeller performance measurement system for high altitude UAV was designed and applied to the wind tunnel test for 2 propeller models with a diameter around 1 m. Mechanical power of the propeller was directly measured by using the torque sensor installed on the rotating axis. The thrust of whole operation body including the propeller was measured by thrust road cell. The guide rail system was suggested to reduce the weight influence of operation body on the thrust road cell. The influence of each measured variables on the aerodynamic coefficients was studied with the repeatability and uncertainty analysis. This analysis result shows that the accuracies of the road cell and the wind velocity were major factors for the thrust coefficient. Propeller performance with typical RPM was measured with various wind speeds and the test results was summarized by performance coefficients for 5 different RPM.