• Title/Summary/Keyword: 선박거동

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Methodology of Engine Fitness Diagnosis Using Variation of Crankshaft Angular Speed (엔진 회전속도 변화를 이용한 상태진단 기법에 관한 연구)

  • Lee, Byung-Yeol;Ha, Seung-Jin;Lim, Ock-Taeck
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.11
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    • pp.1529-1535
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    • 2011
  • Improvement of the thermal efficiency in operation and maintenance of low- and medium-speed engines is a kind of never-ending requirement in the maritime power plant business. For the purpose of improving engine management efficiency, a principal factor that represents the fitness of the engine should be identified. Gas pressure, gas temperature, and vibration have all been used as this factor. However, they have limitations in terms of response speed and diagnosis accuracy. The EFR (engine fitness ratio) is suggested as a new diagnostic factor in this paper. The EFR is defined as the ratio of particular frequencies in the frequency domain and represents the fitness of an engine. It is calculated from the fluctuation pattern of the crankshaft angular speed. The EFR was verified using an experimental method for a low-speed engine and an analytic method for a medium-speed engine.

A Study on the Sloshing Reduction of a Cargo Fuel Tank with Baffle (배플을 적용한 Cargo용 연료탱크 내부의 슬로싱 저감 연구)

  • Yoon, Bo-Hyun;Yoon, Jun-Kyu;Lim, Jong-Han
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.8
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    • pp.1074-1083
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    • 2010
  • Recently sloshing that fluid in fuel tank is undulating by the external force during motion of automobile, ship and aircraft is greatly affecting by damaging the inside of structure. It's most important to precisely analyze the behavior of fluid by computational fluid dynamics for minimizing the effect of sloshing for the loaded fuel. This study characterized volume of fluid and pressure according to the length and number of vertical baffle and horizontal baffle in fuel tank for Kia Frontier cargo and analyzed for reduction of sloshing during driving on corner and hill by using ADINA-CFD. As a result of analysis, the optimum length for sloshing reduction shows 0.19 m for vertical baffle and 0.08 m for horizontal baffle. And it shows that vertical baffle is better for the reduction effect of sloshing during driving on corners, on the other hand, horizontal baffle is effective and stable during driving on hills.

Investigation on optimum applied potential for corrosion resistance and cavitation-erosion damage reduction of Al alloy in seawater (알루미늄 합금의 해수 내 내식성 및 캐비테이션-침식 손상 저감을 위한 적용전위 규명)

  • Jeong, Gwang-Hu;Park, Il-Cho;Lee, Jeong-Hyeong;Han, Min-Su;Kim, Seong-Jong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.112-112
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    • 2018
  • 알루미늄 합금은 내구성과 내식성이 우수한 경량 재료이다. 그 중 Al-Mg계 5083 Al 합금은 가공성 및 용접성이 우수하여 선체 재료로 널리 이용되고 있다. 이는 선체 중량의 경량화로 인해, 연료비 절감과 빠른 선속 등 다양한 이점을 지니기 때문이다. 그러나 선박의 고속화에 따라 선체에 가해지는 유체충격이 증가하고, 압력 저하에 기인하여 캐비테이션-침식 손상이 증가할 뿐만 아니라, 염소이온이 존재하는 해수환경에서는 침식과 부식의 시너지효과로 인하여 재료의 손상이 더욱 가속화된다. 이에 대한 다양한 방지책들이 제안되고 있으나, 강한 충격압을 동반한 캐비테이션 침식-부식 복합 손상 환경에서는 다소 한계가 있다. 따라서 본 연구에서는 알루미늄 5083에 대하여 캐비테이션 환경 하에서 일정 전위를 인가하며 침식-부식 손상이 최소화 되는 전위 구간을 규명하고자 하였다. 먼저, 분극 실험을 선행하여 재료의 전기화학적 거동을 파악 한 후 적용 전위구간을 선정하여, 해당 전위를 인가한 상태에서 캐비테이션 실험을 실시하였다. 전기화학적 분극실험과 캐비테이션-전기화학 복합 실험은 25C25C의 해수 하에서 실시하였으며, 시험편의 노출면적은 3.24cm23.24cm2으로 하였다. 분극 실험은 개로전위로부터 +3 V까지 2 mV/s의 분극속도로 전위를 인가하였고, 기준전극으로 Ag/AgCl, 대극으로 백금전극을 사용하였다. 캐비테이션-전기화학 복합 실험은 정전위를 인가한 상태에서 대향형 진동법으로 진동수 20 kHz, 진폭 30μm30μm 진동을 20분간 가하였으며, 혼팁과 시험편 사이의 거리는 1 mm로 일정하게 유지하였다. 실험 후 표면 손상의 정량적 분석을 위해 인가된 전위별 전류밀도를 비교하고, 무게감소량을 측정하였으며, 손상경향 파악을 위하여 3D광학현미경과 주사전자현미경(SEM)을 통해 표면을 분석하였다.

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A Study on the Sloshing of Cargo Tanks Including Hydroelastic Effects (유탄성을 고려한 탱크내 슬로싱에 대한 연구)

  • Dong-Yeon Lee;Hang-Shoon Choi
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.4
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    • pp.27-37
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    • 1998
  • The sloshing is very important in a safe transport of the liquid cargo by a ship. With the increasing number of supertanker and LNG carriers, this problem has become increasingly more important. In order to study the magnitude and characteristics of impact pressures due to sloshing, experiments ware performed with a rectangular tank and compared with numerical results. Structural responses of tank wall under impulsive pressures were measured. Structural vibrations induced by the sloshing load were analysed by including hydroelastic erects in terms of added mass and damping. To check the validity of the numerical model, the natural frequencies of plate in air and water were compared with measurements, and a good agreement was found. In the case that a plate vibrates under impulsive loads, the pressure on the flexible plate is larger than that on the rigid plate without hydroelastic effects, which was confirmed experimentally. The frequency of oscillatory pressure as well as accel%pion coincides with the natural frequency of plate in water.

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Detection of Abnormal Vessel Trajectories with Convolutional Autoencoder (합성곱 오토인코더를 이용한 이상거동 선박 식별)

  • Son, June-Hyoung;Jang, Jun-Gun;Choi, Bongwan;Kim, Kyeongtaek
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.43 no.4
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    • pp.190-197
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    • 2020
  • Recently there was an incident that military radars, coastal CCTVs and other surveillance equipment captured a small rubber boat smuggling a group of illegal immigrants into South Korea, but guards on duty failed to notice it until after they reached the shore and fled. After that, the detection of such vessels before it reach to the Korean shore has emerged as an important issue to be solved. In the fields of marine navigation, Automatic Identification System (AIS) is widely equipped in vessels, and the vessels incessantly transmits its position information. In this paper, we propose a method of automatically identifying abnormally behaving vessels with AIS using convolutional autoencoder (CAE). Vessel anomaly detection can be referred to as the process of detecting its trajectory that significantly deviated from the majority of the trajectories. In this method, the normal vessel trajectory is gridded as an image, and CAE are trained with images from historical normal vessel trajectories to reconstruct the input image. Features of normal trajectories are captured into weights in CAE. As a result, images of the trajectories of abnormal behaving vessels are poorly reconstructed and end up with large reconstruction errors. We show how correctly the model detects simulated abnormal trajectories shifted a few pixel from normal trajectories. Since the proposed model identifies abnormally behaving ships using actual AIS data, it is expected to contribute to the strengthening of security level when it is applied to various maritime surveillance systems.

Solid Particle Erosion Behavior of Inconel 625 Thermal Spray Coating Layers (Inconel 625 열용사 코팅 층의 고상입자 침식 거동)

  • Park, Il-Cho;Han, Min-Su
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.27 no.4
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    • pp.521-528
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    • 2021
  • In this study, to repair damaged economizer fin tubes on ships, sealing treatment was performed after applying arc thermal spray coating technology using Inconel 625. A solid particle erosion (SPE) experiment was conducted according to ASTM G76-05 to evaluate the durability of the substrate, thermal spray coating (TSC), and thermal spray coating+sealing treatment (TSC+Sealing) specimens. The surface damage shape was observed using a scanning electron microscope and 3D laser microscope, and the durability was evaluated through the weight loss and surface roughness analysis. Consequently, the durability of the substrate was superior to that of TSC and TSC+Sealing, which was believed to be owing to numerous pore defects in the TSC layer. In addition, the mechanism of solid particle erosion damage was accompanied by plastic deformation and fatigue, which were the characteristics of ductile materials in the case of the substrate, and the tendency of brittle fracture in the case of TSC and TSC+Sealing was confirmed.

The Latest Progress on the Development of Technologies for CO2CO2 Storage in Marine Geological Structure and its Application in Republic of Korea (해저 지질구조내 CO2CO2 저장기술의 연구개발 동향 및 향후 국내 실용화 방안)

  • Kang, Seong-Gil;Huh, Cheol
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.11 no.1
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    • pp.24-34
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    • 2008
  • To mitigate the climate change and global warming, various technologies have been internationally proposed for reducing greenhouse gas emissions. Especially, in recent, carbon dioxide capture and storage (CCS) technology is regarded as one of the most promising emission reduction options that CO2CO2 be captured from major point sources (eg., power plant) and transported for storage into the marine geological structure such as deep sea saline aquifer. The purpose of this paper is to review the latest progress on the development of technologies for CO2CO2 storage in marine geological structure and its perspective in republic of Korea. To develop the technologies for CO2CO2 storage in marine geological structure, we carried out relevant R&D project, which cover the initial survey of potentially suitable marine geological structure fur CO2CO2 storage site and monitoring of the stored CO2CO2 behavior, basic design for CO2CO2 transport and storage process including onshore/offshore plant and assessment of potential environmental risk related to CO2CO2 storage in geological structure in republic of Korea. By using the results of the present researches, we can contribute to understanding not only how commercial scale (about 1 MtCO2MtCO2) deployment of CO2CO2 storage in the marine geological structure of East Sea, Korea, is realized but also how more reliable and safe CCS is achieved. The present study also suggests that it is possible to reduce environmental cost (about 2 trillion Won per year) with developed technology for CO2CO2 storage in marine geological structure until 2050.

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Structural Evaluation Method to Determination Safe Working Load of Block Handling Lugs (블록 이동용 러그의 안전사용하중 결정에 관한 구조 평가법)

  • O-Hyun Kwon;Joo-Shin Park;Jung-Kwan Seo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.4
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    • pp.363-371
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    • 2023
  • To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

Monitoring System of Rock Mass Displacement and Temperature Variation for KURT using Optical Sensor Cable (광섬유센서케이블을 이용한 지하연구시설의 지반변위 및 온도변화 감시시스템 구축)

  • Kim, Kyung-Su;Bae, Dae-Seok;Koh, Yong-Kwon;Kim, Jung-Yul
    • The Journal of Engineering Geology
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    • v.19 no.1
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    • pp.63-70
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    • 2009
  • The optical fiber cable acting as a sensor was embedded in the underground research tunnel and portal area in order to monitor their stability and the spatial temperature variation. This system includes two types of sensing function to monitor the distributed strain and temperature along the line, where sensor cable is installed, not a point sensing. According to the results of one year monitoring around the KURT, there is no significant displacement or movement at the tunnel wall and portal slope. However, it would be able to aware of some phenomena as an advance notice at the tunnel wall which indicates the fracturing in rockmass and shotcrete fragmentation before rock falls accidently as well as movement of earth slope. The measurement resolution for rock mass displacement is 1 mm per 1 m and it covers 30 km length with every 1m interval in minimum. In temperature, the cable measures the range of 160600C160600C with 0.01C0.01C resolution according to the cable types. This means that it would be applicable to monitoring system for the safe operation of various kinds of facilities having static and/or dynamic characteristics, such as chemical plant, pipeline, rail, huge building, long and slim structures, bridge, subway and marine vessel. etc.

Study on Cavitation Noise Predictions for an Elliptic Wing (타원형 날개에 대한 공동소음 예측 연구)

  • Jeong, Seung-Jin;Hong, Suk-Yoon;Song, Jee-Hun;Kwon, Hyun-Wung;Park, Il-Ryong;Seol, Han-Shin;Kim, Min-Jae
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.757-764
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    • 2019
  • Depressurization occurs around underwater objects moving at high speeds. This causes cavitation nuclei to expand, resulting in cavitation. Cavitation is accompanied by an increase in noise and vibration at the site, particularly in the case of thrusters, and this has a detrimental ef ect on propulsion performance. Therefore, predicting cavitation is necessary. In this study, an analytical method for cavitation noise is developed and applied to an elliptic wing. First, computational fluid dynamics are performed to obtain information about the flow fields around the wing. Then, through the cavitation nuclei density function, number of cavitation nuclei is calculated using the initial radius of the nuclei and nuclei are randomly placed in the upstream with large pressure drop around the wing tip. Bubble dynamics are then applied to each nucleus using a Lagrangian approach for noise analysis and to determine cavitation behavior. Cavitation noise is identified as having the characteristics of broadband noise. Verification of analytical method is performed by comparing experimental results derived from the large cavitation tunnel at the Korea Research Institute of Ships & Ocean Engineering.