• Journal of Navigation and Port Research
• /
• v.32 no.10
• /
• pp.759-764
• /
• 2008

The planing craft is designed specifically to achieve comparatively high speed on the surface of the water. Most of planing crafts have installed the spray strip in decreasing of wave impaction and improving motion performance of rolling and pitching et al. It is known to reduce the spray and frictional resistance by the effect of lift and improvement of wave profile in high speed. In this paper, the high speed planing crafts with & without spray strip in bottom were performed to compare the resistance performance by model-test. In conclusion, the high speed planing crafts with spray strip in bottom was proved to effect of the resistance decrement of $3.0{\sim}5.0%$.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.4 no.2
• /
• pp.83-95
• /
• 2012

In the present study, the structural response of breakwaters installed on container carriers against green water impact loads was numerically investigated on the basis of the fluid-structure interaction analysis. A series of numerical studies is carried out to induce breakwater collapse under such conditions, whereby a widely accepted fluid-structure interaction analysis technique is adopted to realistically consider the phenomenon of green water impact loads. In addition, the structural behaviour of these breakwaters under green water impact loads is investigated simultaneously throughout the transient analysis. A verification study of the numerical results is performed using data from actual collapse incidents of breakwaters on container carriers. On the basis of the results of a series of numerical analyses, the pressure distribution of green water was accurately predicted with respect to wave mass and velocity. It is expected that the proposed analytical methodology and predicted pressure distribution could be used as a practical guideline for the design of breakwaters on container carriers.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.1 no.1
• /
• pp.39-49
• /
• 2009

The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW), laser welding and friction stir welding (FSW), FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base) alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009), jointly funded by its member agencies.

• Journal of the Society of Naval Architects of Korea
• /
• v.54 no.4
• /
• pp.275-285
• /
• 2017

In order to predict the sailing performance of a LNGC during actual operation, it is necessary to consider not only the information about resistance, maneuverability etc. but also the information such as sea route and sailing scenario etc., comprehensively. In this paper, we propose a new approach to conduct the sailing simulation of a LNGC without full scale measurement data. Latitude, longitude, sea route, speed over ground, time in UTC obtained from AIS data are substituted for the measured data. By combining the model test results, design information, and AIS data, prediction of sailing performance is conducted from the coast of southern Taiwan to the coast of Madagascar. The simulation is verified by comparing the calculated time histories of RPM and power with those of measured RPM and power.

• Journal of the Society of Naval Architects of Korea
• /
• v.54 no.4
• /
• pp.344-351
• /
• 2017

CAD systems used in various manufacturing industries have been rapidly switched from 2D to 3D. 3D-based design is becoming common in the shipbuilding industries too. However, there is still a demand for 2D drawings for ship production. So, it is necessary to continually improve 2D drawings. One way to improve 2D drawings is to add production information to the drawings. To do this, it is necessary to define the relation between the geometry information and the production information. Various types of drawings, which is inevitable because each drawing has its own purpose, make it difficult to define relations. This process can be simplified if the drawing information is neutralized. XML is a standard format for defining neutral data, and is already being used in various fields. In this study, a neutral augmented drawing has been defined by neutralizing the drawing information based on XML, and implemented for the allocation of their information with high quality of readability as well.

• Journal of the Society of Naval Architects of Korea
• /
• v.58 no.1
• /
• pp.10-16
• /
• 2021

This paper systematically investigates and correlates pressure fluctuation and nominal wake characteristics according to the angle of the vortex generators by introducing the angle adjustment method of the Vortex Generator (VG). The vortex generators are installed at the port and starboard of a model ship. The vortex generator performance test is executed on a model ship installed in the Large Cavitation Tunnel (LCT) and the angle of VG is freely controlled by a servo motor. The systematic test results for the vortex generator show that the well-designed VG is an effective appendage for reducing the pressure fluctuation level and shows the direction of VG's angular design optimization.

• The Journal of Economics, Marketing and Management
• /
• v.9 no.1
• /
• pp.25-40
• /
• 2021

Purpose: The forecasting is the likelihood scientifically proved judgment about the prospects, the possible conditions of this or that phenomenon in the future and (or) about the alternative ways and the means of their realization. To adapt the instruments of budgeting for the analysis cash flow of company. Research design, data and methodology: The creates the budget of cash flow were carried out on the basis of data of the report for the 2017 of corporations POSCO and in the first half of the 2018 Daewoo Shipbuilding & Marine Engineering of South Korea. Results: The simultaneous use of budgeting techniques and the simple financial analysis allows to systematize the transactions, to identify the main problem areas in the movement cash flows. Therefore, working capital analysis is to determine the limits of their fluctuations in view of the changes in the business processes. Conclusions: In the pedagogical context solved the features of budgeting in the part evaluation current assets, its financing, its elements: the cash, the debtor. In the process of budgeting of cash flow, in credit budget, in financial budget we can see the main indicators: the current assets, the functioning capital, the optimum number of debtors, the optimum amount of cash and another.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.13 no.1
• /
• pp.545-553
• /
• 2021

International Maritime Organization (IMO) have recently discussed the technical problems related to the second-generation intact stability criteria of ships. The second-generation intact stability criteria refer to five modes of vulnerability when the ship sailing in the ocean. In this study, we described a method to verify the criteria of the surf-riding/broaching. In case that Lv1 (Level 1) vulnerability criteria is not satisfied based on the relatively simple calculation using the Froude number (Fn), we presented the calculation procedure for the Lv2 (Level 2) criteria considering the hydrodynamics in waves. The results were reviewed based on the data for given previous ships. In absence of ship-specific data, a similar Lv2 result was confirmed by comparing the result obtained by calculating the added mass with the case where the added mass was 10% of the ship mass. This result will contribute to basic ship design process according to the IMO draft regulation.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.1
• /
• pp.131-139
• /
• 2022

The exchange of goods over the sea is a situation in which the amount of trade between countries is gradually increasing. In order to maintain the optimal operating condition, the ship maintains stability and optimal operating conditions by inserting or withdrawing ballast water from the ballast tank according to the loading condition of cargo capacity is also increasing. Control valves play an important role in controlling fluid flow in these pipes. When the flow rate is controlled using a control valve, problems such as cavitation, flashing, and suffocating flow may occur due to high differential pressure, and in particular, damage to valves and pipes due to cavitation is a major problem. Therefore, in this study, the cavitation phenomenon is reduced by installing orifices at the front and rear ends of the high differential pressure control butterfly valve to reduce the sudden pressure drop at the limiting part of the butterfly valve step by step. The flow coefficient according to the shape of the orifice, the degree of cavitation occurrence, and the correlation were analyzed using a CFD(Cumputational Fluid Dynamics), and an optimal orifice design for reducing cavitation is derived.

• Journal of the Society of Naval Architects of Korea
• /
• v.59 no.6
• /
• pp.372-384
• /
• 2022

Total shipping accounts for 2.9 % of the annual average percentage of global anthropogenic GHG emissions. The International Maritime Organization implements EEDI (Energy Efficiency Design Index), Energy Efficiency eXisting-ship Index (EEXI), and Carbon Intensity Indicator (CII) as regulatory frameworks for shipping decarbonization. The Republic of Korea has enforced the Act on Development and Popularization of Greenship from 2020 and publicly announced the 1st national plan which was named 『2030 Greenship-K Promotion Strategy』 for the activation of a greenship market. The Greenship Certification Scheme is going on for the sustainability of Korean shipbuilding and shipping industries, to secure clean maritime environments, as well as to contribute to the national economy. Greenship Certification guarantees the credit of such eco-friendly technologies and products for shipping. The certification is going to be the basis of industrial competitiveness in coastal and international shipping. This study investigates an existing certification process, identifies the limitations, and proposes the process improved with several case studies. The improved certification scheme may have rationality for Net-zero with regard to climate alignment.