• Journal of Navigation and Port Research
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• v.46 no.4
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• pp.303-312
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• 2022

Bridges across waterways act as interference factors, that reduce the navigable water area from the perspective of navigation safety. To analyze the safety navigational width of ships navigating bridges across waterways, the optimal traffic distribution based on AIS data was investigated, and ships were classified according to size through k-means clustering. As a result of the goodness-of-fit analysis of the clustered data, the lognormal distribution was found to be close to the optimal distribution for Incheon Bridge and Busan Harbor Bridge. Also, the normal distributions for Mokpo Bridge and Machang Bridge were analyzed. Based on the lognormal and normal distribution, the analysis results assumed that the safe passage range of the vessel was 95% of the confidence interval, As a result, regarding the Incheon Bridge, the difference between the normal distribution and the lognormal distribution was the largest, at 64m to 98m. The minimum difference was 10m, which was revealed for Machang Bridge. Accordingly, regarding Incheon Bridge, it was analyzed that it is more appropriate to present a safety width of traffic by assuming a lognormal distribution, rather than suggesting a safety navigation width by assuming a normal distribution. Regarding other bridges, it was analyzed that similar results could be obtained using any of the two distributions, because of the similarity in width between the normal and lognormal distributions. Based on the above results, it is judged that if a safe navigational range is presented, it will contribute to the safe operation of ships as well as the prevention of accidents.

• Journal of Korea Port Economic Association
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• v.25 no.2
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• pp.73-94
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• 2009

In this paper the benefit was forecasted for traffic safety facilities to be constructed along the inland waterway between Phnom Penh and Chong Kneas(Siem Reap) port in Cambodia. First of all, the number of cruise ships passengers and cargo volumes were predicted. Second, the traffic volume of the cruise ships and cargo ships were calculated according to the prediction. Last, the safety benefit of traffic safety facilities was forecasted with the traffic after surveying the waterway accidents. The other benefit was also presented by converting the effect of relieving the emotional burden of navigators into currency value. Accordingly the entire benefit was estimated to be $14,990, $20,950 and $28,540 for pessimistic, moderate and optimistic prospects, in 2011. And then the entire benefits are calculated as $28,320, $63,060 and $95,230 for each prospect in the final estimation year 2020.

• Journal of the Korean Institute of Navigation
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• v.18 no.4
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• pp.83-118
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• 1994

In this study, the writer embodies factors influencing on ship safety management by an empirical survey. In the empirical survey, the writer used a questionnaire. 1, 271 proper data was obtained from 4, 240 Korean seamen working in 152 domestic and 60 foreign merchant ships. Reliability was tested by Cronbach's Alpha and a conceptual validity by Factor Analysis. Hypotheses established in this study were tested by Correlation and Multiple Regression Analysis. Results of analysis are as follows: Firstly, three levels(i.e. planning, doing, and evaluation) of safety management and satisfaction level of shipboard life correlate significantly with level of ship safety management and between them(P<0.05) Secondly, satisfaction level of shipboard life, evaluation and planning levels of safety management influence significantly on level of ship safety management(P<0.05).

• Korean Journal of Computational Design and Engineering
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• v.13 no.3
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• pp.227-234
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• 2008

The number of marine accidents have been decreased since various equipments for navigation control have been introduced to the marine vessels. However, disastrous marine accidents such as ship collisions are occurred more frequently. Therefore, IMO(International Maritime Organization) is enforcing the design requirement of structural strength for marine vessel. Also EU countries are developing new design methodologies and design tools to suggest the design guidance which can minimize the damage of commercial vessels in case of marine collision accidents. In this study, an integrated design system for the safety assessment has been presented to enhance the safety of damaged ships in marine collision accidents. The architecture of system is described by use-cases and IDEF functional analysis. Then an integrated system for safety assessment of damaged ship which is considering both damage stability and structural safety has been developed to support the ship design in early stage.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.95-98
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• 2006

Many LNG ships will be constructed in Korea and the demand of safety valves is increasing. The most important performance of the developed safety relief valves for LNG ship is flow capacity. Flow capacity tests for 8 sizes of developed safety valves were conducted in the high pressure gas flow standard system in KRISS. The initial spring force adjustment was important for setting pressure of the safety valve. The procedure of data reduction and evaluation of the safety valve performance are suggested. This procedure was approved by French Bureau Veritas and Lloyd's Register.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1331-1339
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• 2012

Safety valve used in LNG/LNG-FPSO ships is a high value valve, and it plays an important role in maintaining a fixed level of pressure by emitting LNG gas out of pipes in LNG piping system under the cryogenic and high-pressure condition when the pressure of the system connected with the LNG storage tank and pipes reaches over the set pressure. The structural stability is required for the inner pressure and thermal load because of the cryogenic and high-pressure condition, and a reliability of the safety valve is necessary for impact and deformation by opening the valve. But, the safety valve, which plays a key role for a safety of the transport and storage system, is depended on imports for over 90%, and in domestic production, the design of the valve is performed on the basis of experiences of the works without quantitative analysis for the inner operation characteristics and structural stability of the valve. In this study, impact velocity is calculated by theoretical analysis for obtaining the structural stability of the guide according to the impact load by opening the valve. The shape of the guide and the diaphragm for satisfying the structural stability are suggested and verified by using a thermal-structural analysis.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.25-36
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• 1995

The application of the reliability analysis is investigated as a probabilistic approach to the assessment of ship's structural strength and to the establishment of design format for longitudinal strength. Reliability analyses are carried out for 34 ships of tankers and bulk carriers built in HHI for some failure modes such as tensile yielding, compressive buckling and ultimate strength of hull girder. The safety assessment of each ship, the calculation of sensitivity factors and the derivation of target reliability index are performed. As results. the difference of reliability indices among ships is great for all modes. To provide more uniform levels of safety the establishment of new strength criteria using partial safety factors is performed. The partial safety factors for the design format are obtained according to the AFOSM method and the reliability-conditioned(RC) method. Finally, a design format using partial safety factors has been proposed. We could find out that new strength criteria can produce consistent reliability indices which are close to the target value.

• Journal of the Korean Society of Safety
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• v.33 no.6
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• pp.15-21
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• 2018

Ships may collide with reefs or other objects during operation, when arriving or departing ports. The hull plate may be damaged due to the contact with other ships. The total number of domestic powered fishing vessels has decreased, but that of FRP fishing vessels has increased by 0.7% and the ratio of FRP fishing vessels to the total fishing vessels increased to 96%. Recently, fishing vessels has been used as fishing boats for income of non-fishermen as well as fishermen. Therefore, safety management for repair and maintenance is necessary. The penetration of moisture and moisture in the composite material such as FRP may deteriorate the mechanical properties and the salt (NaCl) component of the damaged portion may cause a relatively high deterioration in material strength. The gel coat painting is the final stage of repairs ans maintenance of FRP fishing vessels. The thickness criteria in the domestic and foreign gel coat is 0.3~0.762 mm. The joint specimens, which was immersed in seawater for 120 days, were compared with those without seawater immersion. As a result, the tensile strength was 83 ~ 121.8% and the flexural strength was 83 ~ 113% compared with the specimens without seawater immersion. According to the previous study the tensile strength decreased by more than 29% and the flexural strength decreased by more than 50% when the composite material was immersed in seawater for 1,083 hours without coating. As a result, it was found that the gel coat with 0.5 mm thickness is very effective in preventing the strength decrease of the composite material.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.385-394
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• 2017

Objective: The aim of this study is to investigate how to design effective virtual reality-based training (i.e., virtual training) in maritime safety and to present methods for enhancing interface fidelity by employing immersive interaction and 3D user interface (UI) design. Background: Emerging virtual reality technologies and hardware enable to provide immersive experiences to individuals. There is also a theory that the improvement of fidelity can improve the training efficiency. Such a sense of immersion can be utilized as an element for realizing effective training in the virtual space. Method: As an immersive interaction, we implemented gesture-based interaction using leap motion and Myo armband type sensors. Hand gestures captured from both sensors are used to interact with the virtual appliance in the scenario. The proposed 3D UI design is employed to visualize appropriate information for tasks in training. Results: A usability study to evaluate the effectiveness of the proposed method has been carried out. As a result, the usability test of satisfaction, intuitiveness of UI, ease of procedure learning, and equipment understanding showed that virtual training-based exercise was superior to existing training. These improvements were also independent of the type of input devices for virtual training. Conclusion: We have shown through experiments that the proposed interaction design results are more efficient interactions than the existing training method. The improvement of interface fidelity through intuitive and immediate feedback on the input device and the training information improve user satisfaction with the system, as well as training efficiency. Application: Design methods for an effective virtual training system can be applied to other areas by which trainees are required to do sophisticated job with their hands.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.487-494
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• 2011

The safety valve used in LNG/LNG-FPSO ships plays an important role in maintaining a fixed level of pressure by emitting LNG gas out of the pipes in the LNG piping system. The discharge coefficient is regarded as the most important factor in the valve performance. To satisfy the ship's classification, the discharge coefficient of the safety valve must usually be over 0.8. Despite the importance of understanding the flow phenomena inside the safety valve, the valve design is usually based on experience and experiments. We carried out a computational fluid dynamics (CFD) investigation using the ANSYS-CFX software. We observed the flow phenomena inside the valve and measured the discharge coefficients according to changes in the valve lift, which is the distance between the exit of the nozzle and the lower part of the disc plate. We verified our CFD results for the discharge coefficients using available experimental data.