• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.620-630
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• 2008

The characteristics of complicated propeller wake influenced by hull wake are investigated by using a two-frame PIV (Particle Image Velocimetry) technique. As the propeller is significantly affected by the hull wake in a real marine vessel, the measurements of propeller wake under the hull wake would be certainly necessary for more reliable validation and the prediction of numerical simulation with wake modeling. Velocity field measurements have been conducted in a medium-size cavitation tunnel with a hull wake. Generally, the hull wake generated by the boundary layer of ship's hull produces the different loading distribution on the propeller blade in both upper and lower propeller planes. The difference of the propeller wake behaviors caused by the hull wake is discussed in terms of axial velocity, vorticity and turbulence kinetic energy distribution in the present study.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.196-197
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• 2011

Rudder, one of the most important component in the marine vessel, is now being decreased life time to serve due to cavitation erosion, vortex current, high flow speed suffer from ship speed going up dramatically. In this study, 10 kinds of thermal spray coating materials(2 of Zn alloy series, 3 of Al alloy series, 3 of Cu alloy series, 2 of STS alloy series) are chosen to apply on specimens and analyze micro structure, metallic composition, properties(porosity, oxidation) by using visual observation, XRD, EDX etc.. Additionally, to refine the characteristic of corrosion endurance for thermal spray coating layer, compared with thermal spray process and 5 kinds of heavy duty painting and AC paint (Anti-Corrosion Paint). Based on above mentioned experimental results, a priority of all coated specimens on corrosion-erosion endurances finalized and summarized there by desirable composition and process of thermal sprayed material properly.

• Journal of Korean Port Research
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• v.7 no.1
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• pp.89-114
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• 1993

ICLL 66 is the most widely ratified instrument of the IMO and is, along with the International Convention on Safety of life at Sea (SOLAS), the primary document setting forth internationally agreed ship safety standards. ICLL 66 set freeboard requirement based on experience gained from the first Load Line Convention in 1930 and on contemporary developments in ship design. Reexamination of ICLL 66 is indicated by the proliferation of novel ship designs for which it lacks adequate regulations and by significant advancements in analytical seakeeping and deck wetness prediction techniques now available to the designer. In this paper, the Freeboard Advisory Group reviews these issues against the changing climate of the marine industry and maritime administrations, discusses the state of the art in analytical seakeeping programs, and outlines a series of recommendations for the establishment of a new international load line convention for the next century. The steps needs for an international program at IMO are discussed and a new convention is proposed.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.201-201
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• 2015

국민의 생명과 재산을 보호하기 위해 아무리 강조해서 지나치지 않는 안전을 중요시 하는 우리나라는 각종 재난 사고가 많이 발생한다. 이는 안전의식이 결여되었기에 발생하는 사고들이다. 특히 안전사고와 관련해 다사다난한 일들이 많이 있는데 책임감을 비롯한 본인과 타인의 안전의식 결여로 일어난 문제들이다. 우리나라는 재난에 좀 더 현명하고 안전하게 대처하기 위해서 사전의 적극적인 예방과 사고 후의 빠른 조치, 건전한 안전의식 함양이 필요하다. 2014년 4월 16일 세월호 침몰 사고로 수백 명의 사상자를 낸 대형 참사를 계기로 국민들의 해난(해양사고) 안전에 대한 관심이 높아졌다. 위기상황 속에서 당황하지 않고 올바르고 안전한 판단으로 신속히 대피 할 수 있도록 미리 체험하는 안전체험교육시설을 통해 체계적인 대비로 인명피해를 줄이기 위한 대책이 필요하다. 본 연구는 해난(해양사고)로 인한 인명피해 위험도의 관리기법을 수립하고 재난 관리 체계 중 대비(Preparedness)에 중점을 두고 체험교육을 통해 어떤 효과가 있는지 설문조사를 실시하여 연령대별 체험자들의 반응을 토대로 가상적인 방법을 적용한 인명피해 위험도 저감효과를 분석한다. 국내 여수 해양경비안전교육원에서 올해부터 한국해양소년단연맹과 협업하여 '바다로 캠프' (해양안전 체험 프로그램)를 운영하여 위기 대응 훈련을 실시 할 계획이다. 따라서 본 연구에서는 교육원 대상자를 대상으로 설문조사를 실시하고자 한다.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.2 s.140
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• pp.142-150
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• 2005

Recently, the gas transportation system for CNG(Compressed Natural Gas) has been developed and several innovative approaches are presented from the aspects of commercial demand. In this study, a new type of 20ft container shape CNG tank with two and four cylinder intersections by using the intersecting spheres has been proposed. And the structural analysis of CNG tank with Mildsteel, API High Tensile Steel, Al-alloy and FRP has been carried out to compare the different types of pressure vessels of materials used. The analysis result shows that the proposed intersectional cylindrical type of CNG tank can be applied to the gas transportation system. And further study on the commercial analysis and associated equipments should be carried out for the practical applications.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.2
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• pp.201-211
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• 2018

This paper illustrates recent advancements relative to a non-conventional propulsion system for boats and is based on two previous papers of the author presented at a conference (see Muscia, 2015a,b). The system does not consider propellers and utilizes the vibration generated by two or more pairs of counter rotating masses. The resultant of the centrifugal forces applies an alternate thrust to the hull that oscillates forward and backward along the longitudinal axis of the boat. The different hydrodynamic drag forces that oppose to the oscillation produce a prevalently forward motion of the vessel. The vibration that causes the motion can be suitably defined to maximize the forward displacement and the efficiency propulsion of the system. This result is obtained by using elliptical gears to rotate the counter rotating masses. The computation of the propulsion efficiency is based on a suitable physical mathematical model. Correlations between numerical experiments on models and possible full scale application are discussed. Some remarks in relation to practical applications and critical issues of the propulsive solution are illustrated. The results have been obtained with reference to a CAD model of a real boat already manufactured whose length is approximately equal to 13 m.

• Journal of the Korea Safety Management & Science
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• v.21 no.3
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• pp.23-27
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• 2019

The first aim of the study is to improve the productivity by uniformizing the thickness of coating and reducing quality-inspection time. The second aim is to cut down on the raw materials for coating by prevent the waste of spraying in the air during a painting process through a real-time coating-size-recognition monitering to fit the target components. To achieve the two aims, a simplified version of automatic coating control system for recognition of coating for vessels and Spray. With the sytem, following effects are expected: First, quality improvement will be achieved by uniformizing the film-thickness. Second, it will reduce the waste of coating paint by constructing the speed of the coating, the spray gun robot transfer time, and the number of DBs according to the size of the vessel. Third, as a 3D industry, it will be able to solve the difficulty of supply of labors and save up the labor costs. Therefore, in the future, further research will be needed to be applied to various products with DB design that designates the variable value, which is added for each type of pieces by comparing the difference between various types of workpieces and linear ones.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.466-474
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• 2021

A wet type scrubber for merchant vessel uses super austenitic stainless steels with pitting resistance equivalent number (PREN) of 40 or higher for operation in a harsh corrosive environment. However, it is expensive due to a high nickel content. Thus, electrochemical behavior and cavitation erosion characteristics of UNS S32750 as an alternative material were investigated. Microstructure analysis revealed fractions of ferritic and austenitic phases of 48% and 52%, respectively, confirming the existence of ferritic matrix and austenitic island. Potentiodynamic polarization test revealed damage at the interface of the two phases because of galvanic corrosion due to different chemical compositions of ferritic and austenitic phases. After a cavitation test, a compressive residual stress was formed on the material surface due to impact pressure of cavity. Surface hardness was improved by water cavitation peening effect. Hardness value was the highest at 30 ㎛ amplitude. Scanning electron microscopy revealed wave patterns due to plastic deformation caused by impact pressure of the cavity. The depth of surface damage increased with amplitude. Cavitation test revealed larger damage caused by erosion in the ferritic phase due to brittle fracture derived from different strain rate sensitivity index of FCC and BCC structures.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.214-222
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• 2022

This study calculated the on-site measurement (Tier 4) of greenhouse gases emitted during the production stage of major fishing periods that utilize set nets and bamboo weir fishing boats. In addition, using theoretically calculated results (Tier 1), the emission factor presented by the Intergovernmental Panel on Climate Change (IPCC) was comparatively analyzed. On average, carbon emissions for each operating period in the bamboo weir and set net were calculated to be 0.16 and 3.58 kg CO₂ time^-1, respectively; and the measurement values (Tier 4) for each tool were about 4-17 times lower than their respective theoretical values (Tier 1). Significant differences were found based on engine performance. As port entry, port departure, and operating periods of the vessels show negligible variation with short distances, the operation of the vessel engine was considered as the main variable for carbon emissions in anchovy set net fishing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.2
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• pp.110-116
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• 2023

In this study, samples of sea anchor canopy cloth mainly used in Korean jigging fishing vessels were collected and tested for performance evaluation. The canopy cloth of sea anchor is a basic element of form composition that is known to have the greatest influence on anchor performance. In order to evaluate the performance of sea anchor canopy cloth, five types of samples were tested for new metric count, tensile strength, water vapour transmission rate and drying speed according to the national standard (KS), and some correlations were identified. As a result of the test, the new metric count of cloths was 335.5-443.4 denier in warp and 217-447.6 denier in weft, and the minimum tensile strength was 860 N in warp direction and 430 N in weft direction. The apparent number and tensile strength of cloth were proportional, the water vapour transmission rate of the sample was 206.8 g/m²h, and the drying speed was 90-100 min. This study partially confirmed the performance evaluation based on speculation by the standard test method, and further research is needed on the clear relationship between the research results and the performance of the sea anchor.