• Title/Summary/Keyword: marine vessel

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Effect of pre-post injection timing of diesel fuel for naval vessel on the combustion and emission characteristics in an optically-accessible single cylinder diesel engine (단기통 디젤엔진에서 함정용 디젤유의 전·후 분사시기가 연소 및 배출가스 특성에 미치는 영향)

  • Lee, Hyungmin
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.7
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    • pp.868-876
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    • 2014
  • The objective of this study is focused on the analyzing combustion, carbon monoxide and hydrocarbon emission characteristics of marine diesel oil, utilized for naval propulsion engine, with varying pre-post injection timing of an optically accessible single cylinder engine. And also the combustion process is analyzed by means of a high speed camera visualization. On the result of retarding pre-injection timing toward main injection timing, the mean effective pressure and maximum pressure of combustion chamber are increased; however, the heat release rate is decreased. Furthermore, the emission rates of carbon monoxide and hydrocarbon are reduced in this case. In hence, when a post-injection timing is advanced, the mean effective pressure and maximum pressure are increased, because the combustion has been performed under the high temperature and high pressurized environment during main injection time, and the emission rates of carbon monoxide and hydrocarbon are increased. From the experimental results, it considered that retarding of pre-injection timing affects to shorten the ignition delay of main injection clearly, and to raise the flame intensity comparing to the advanced state. The ignition delay during post-injection is not appeared at any post-injection time, but the flame intensity has been weakened gradually according to the retarding of post-injection timing.

A Study on the Improvement of the Maritime Safety Supervisor System for the Reinforcement of Coastal Ship Safety Control (내항선 안전관리강화를 위한 해사안전감독관 제도 개선 연구)

  • Lee, Seok-Mal
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.1
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    • pp.43-55
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    • 2018
  • The biggest change in the field of coastal ship safety control since the accident of passenger ship Sewol has been the introduction of the maritime safety supervisor system. With its introduction, the safety control system in coastal passenger ships was changed from consisting of operation managers and marine police to operation managers and a newly-introduced maritime safety supervisor. The safety control system for coastal cargo ships was also converted from relying on ship inspection officers to having a maritime safety supervisor and ship inspection officers. However some negative elements have surfaced due to confusion related to the scope of work in the coastal cargo shipping field. These have been caused by dividing the supervisory agency, a lack of work continuity given non-permanent public official status, low supervisor qualifications overlooking reality, and limitations of the order for improvement to secure seaworthiness. It is essential that the maritime safety supervisor system be solidified to reinforce coastal ship safety control. Therefore, systematic safety control in the coastal cargo shipping industry should be conducted by a single, integrated government agency, and the area covered by the order for improvement to secure seaworthiness should be extended. Also limitations of the supervisor recruitment system due to non-permanent public official status should be simultaneously improved. In addition, it is necessary to upgrade supervisor qualifications to require experience with surveyors of international class, ship captains, and chief engineers.

Correlation between Probe Frequency and Echo-Pulse Velocity for Ultrasonic Testing of a Fiber-Reinforced Plastic Hull Plate (복합소재 선체 외판의 초음파 탐상을 위한 탐촉자 주파수와 수신기 음향 속력의 상관관계)

  • Lee, Sang-gyu;Han, Zhiqiang;Lee, Chang-woo;Oh, Daekyun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.2
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    • pp.219-226
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    • 2020
  • Nondestructive testing is one of the most commonly used quality inspection methods for evaluating ship structures. However, accurate evaluation is dif icult because various composite materials, such as reinforcements, resin, and fiber-reinforced plastics (FRPs), are used in hulls, and manufacturing quality differences are likely to exist owing to the fabrication environment and the skill level of workers. This possibility is especially true for FRP ships because they are significantly thicker than other structures, such as automobiles and aircraft, and are mainly manufactured using the hand lay-up method. Because the density of a material is a critical condition for ultrasonic inspection, in this study, a hull plate was selected from a vessel manufactured using e-glass fiber, which is widely used in the manufacture of FRP vessels with the weight fraction of the glass content generally considered. The most suitable ultrasonic testing conditions for the glass FRP hull plate were investigated using a pulse-echo ultrasonic gauge. A-scans were performed with three probes (1.00, 2.25, and 5.00 MHz), and the results were compared with those of the hull plate thickness measured using a Vernier caliper. It was found that when the probe frequency was higher, the eco-pulse velocity of the receiver had to be lowered to obtain accurate measurement results, whereas fewer errors occurred at a relatively low probe frequency.

Expression of Mycosporine-like Amino Acids Biosynthetic Genes in the Chlamydomonas sp. Exposed to Radiofrequency (Radiofrequency에 노출된 Chlamydomonas sp.의 mycosporine-like amino acids 생합성 유전자 발현)

  • Hwang, Jinik;Moh, Sang Hyun;Chang, Man;Lee, Gunsup;Lee, Juyun;Kim, Donggiun;Lee, Taek-Kyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.8
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    • pp.4086-4092
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    • 2013
  • Mycosporine-like amino acids (MAAs) are UV-absorbing substances, and diverse marine organisms have the evolved the capacity to diminished the direct and indirect damaging effects of environmental ultraviolet radiation by synthesis and accumulation of MAAs. In this study, we manufactured a radiofrequency (RF) generation device and applied to microalgal culture. $0.35{\pm}0.05$ mHz of RF was supplied to culture vessel for Chlamydomonas sp. and samples were harvested at the designated time intervals (1, 0.5, 1 and 2 hr). MAAs biosynthetic genes, dehydroquinate synthase homolog (DHQS-like) and nonribosomal peptide synthetase homolog (NRPS-like), were cloned from Chlamydomonas sp. and their gene expressions under the RF exposure were analyzed using qRT-PCR. DHQS-like and NRPS-like gene expressions of Chlamydomonas sp. exposed to RF were increased 1.46 and 1.19 fold at 1 hr, respectively. These results means that DHQS-like and NRPS-like genes can be good biomarker candidates for diagnosis of MAAs biosynthesis in the Chlamydomonas sp.

Effect of Transient Condition on Propeller Shaft Movement during Starboard Turning under Ballast Draught Condition for the 50,000 DWT Oil Tanker (50,000 DWT 유조선의 밸러스트 흘수에서 우현 전타시 과도상태가 프로펠러축 거동에 미치는 영향 연구)

  • Lee, Jae-ung
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.4
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    • pp.412-418
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    • 2020
  • Generally, the propeller shaft that constitutes the ship shaft system has different patterns of behavior due to the ef ects of engine power, propeller load and eccentric thrust, which increases the risk of bearing failure by causing local load variations. To prevent this, different studies of the propulsion shaft system have been conducted focused the relative inclination angle and oil film retention between the shaft and the support bearing, mainly with respect to the Rules for the Classification of Steel Ships. However, in order to secure the stability of the propulsion shaft via a more detailed evaluation, it is necessary to consider dynamic conditions, including the transient state due to sudden change in the stern wakefield. In this context, a 50,000 DWT vessel was analyzed using the strain gauge method, and the effects of propeller shaft movement were analyzed on the starboard rudder turn which is a typical transient state during normal continuous rate(NCR) operation in ballast draught condition. Analysis results confirm that the changed propeller eccentric thrust acts as a force that temporarily pushes down the shaft to increase the local load of the stern tube bearing and negatively affects the stability of the shaft system.

A study on the arrangement of integrated power system for warship (함정의 통합 전력시스템 구성에 관한 연구)

  • Baek, Hyun-Min;Jung, Kyun-Sik;Lee, Myung-Ho;Choi, Jae-Sung
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.9
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    • pp.1070-1074
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    • 2014
  • According to IEEE 1662(2009), IPS is a power system where all prime movers produce electrical power that is shared among propulsion, mission, and ship service loads. Discriminating attributes of integrated power systems are flexibility of movers' arrangements, mechanical decoupling between prime movers and propulsors, an increased level of energy conversion and transmission redundancy, and flexibility of redistributing available electrical power for future electronic weapons. IPS could have various steps of power that can be produced at optimal load of movers. In this study, an evaluation method for optimal arrangement of movers was investigated when an IPS warship is projected. The two factors are utilized for the quantitative analysis which are the weight of system as the fighting power and the fuel consumption per year as the economic feasibility. And also the ways for arrangement of system were studied according to existence of small diesel generator. The evaluation method that decides the optimization level is based on the DEA(Data Envelopment Analysis)

Transient Torsional Vibration Response due to Ice Impact Torque Excitation on Marine Diesel Engine Propulsion Shafting (선박용 디젤엔진 추진축에서 빙 충격 토크 기진에 의한 과도 비틀림 진동 응답)

  • Barro, Ronald D.;Eom, Ki Tak;Lee, Don Chool
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.5
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    • pp.321-328
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    • 2015
  • In recent years, there has been an increasing demand to apply the new IACS(International Association of Classification Societies) standards for ice and polar-classed ships. For ice-class vessel propulsion system, the ice impact torque design criterion is defined as a periodic harmonic function in relation to the number of the propeller blades. However, irregular or transient ice impact torque is assumed to occur likely in actual circumstances rather than these periodic loadings. In this paper, the reliability and torsional vibration characteristics of a comparatively large six-cylinder marine diesel engine for propulsion shafting system was examined and reviewed in accordance with current regulations. In this particular, the transient ice impact torque and excessive vibratory torque originating from diesel engine were interpreted and the resonant points identified through theoretical analysis. Several floating ice impacts were carried out to evaluate torque responses using the calculation method of classification rule requirement. The Newmark method was used for the transient response analysis of the whole system.

Improvement Policy about Inspection systems of Small fishing Vessels (소형어선 검사제도 현실과 개선방안)

  • Lee Kwang-Nam
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.11 no.2 s.23
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    • pp.51-63
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    • 2005
  • In relation with inspection systems of small fishing vessels, Government is drawing up revision of the law about ships safety act(Article 3) on the basis of supporting safe fishing activities to expand the application range of ships safety act for vessels under 2 tons(small fishing vessels) that are exempted from inspection systems. There are two opinions about inspection of small fishing vessels. Government's opinion is that inspection of small fishing vessels must be enforced to confirm small fishing vessels' safety but fishermen's opinion is that inspection systems keep on existing law because inspection systems spends a lot of time and money to the poor and the old. The alternatives for countered opinions is that the poor fishermen's vessels' for living or small vessels' inspection must be operated by themselves in principle and minimizing the limitation through policies is recommended. In addition, Government needs to develop various programs for inspection systems of small fishing vessels like the main fisheries countries. Particularly, in case of operating inspection systems of small fishing vessels, Government needs to consider some solutions for example supporting inspection fee, minimum inspection for confirming vessels' safety, inspecting when a vessel is building, expanding an inspection period.

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Distribution of Water Temperature and Common Squid Todarodes pacificus Paralavae around Korean Waters in 2013, 2014 (2013-2014년 한국주변해역 수온과 살오징어 유생분포)

  • Kim, Yoon-Ha;Lee, Chung Il
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.22 no.1
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    • pp.11-19
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    • 2016
  • Field observation for oceanic conditions and paralarvae of the common squid, Todarodes pacificus in Korean waters were sampled with the Bongo net (diameter: 60 cm, mesh size: $333{\mu}m$) by using oblique tow method with the oceanographic research vessel (Tamgu 12 and Tamgu 20) around Korean waters (middle of the Yellow Sea, northern part of the East China Sea, East Sea) in 2013 and 2014 was carried out. The observation in the Yellow Sea and the northern part of the East China Sea was done in August, 2013 and in the East Sea it was repeated at seven times from June, 2013 to September, 2014. The paralarvae in August of 2013 was not found in the Yellow Sea and one paralarvae was found in the northern part of the East China Sea. In the East Sea, 39 paralarvae during whole observation period were found, mantle length of paralarvae was from 1.7 to 13.5 mm. Surface water temperature in the Yellow Sea was $30^{\circ}C$, and cold water mass lower than $10^{\circ}C$ was occupied in the deep layer than 30 m. In the northern part of the East China Sea, surface water temperature was $31^{\circ}C$, and higher water temperature above $20^{\circ}C$ was found in deeper than 50 m. In the East Sea, optimum temperature for survival, $15-24^{\circ}C$, was existed shallower than 75 m.

The Development of the Anchor Dragging Risk Assessment Program (선박 주묘 위험성 판별 프로그램 개발에 관한 연구)

  • Kim, Joo-Sung;Park, Jun-Mo;Jung, Chang-Hyun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.6
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    • pp.646-653
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    • 2018
  • Marine accidents caused by dragging anchors occur constantly due to enlargement of ships' size and unusual weather conditions. Nevertheless, vessel operators rely on their experience because the calculations of actual holding power and external forces are complex and inconvenient. The purpose of this study was to propose a program for the anchor dragging risk assessment in order to provide crew and VTSO with the information to determine easily the danger of dragging and take appropriate action. The input data in this program were composed of the ship's basic particulars, anchoring condition, and external environment etc. on calculating for the wind pressure, frictional force, drift force, and holding power. Three dragging anchor accidents were applied to the program's data input at the time of the day, then the result was assessed by 'warning', which was verified with a high confidence. As a result, the risk of dragging anchors can be predicted in advance through this program. In further studies, it is necessary to simplify the input data and improve user convenience through automatic input from various equipment.