• Special Issue of the Society of Naval Architects of Korea
• /
• 2013.12a
• /
• pp.30-34
• /
• 2013

Prevention of exhaust gas back flow becomes a great interest to shipyards and shipowners in large container carriers because exhaust gas pollutes cargoes, flows back into the deck house and the engine room area through fresh air intakes and fan rooms, gives harmful damages to the crew's health and also gives thermal damages to electric equipments on the navigation deck. The phenomena of exhaust gas back flow has been studied with the analysis of sea trial records and wind tunnel tests and the height of the exhaust gas pipe, the front area of the deck house, the inflow speed and the position of the radar mast platform has been confirmed as the principal factors of exhaust gas back flow phenomena. The simple empirical formula to estimate exhaust gas back flow phenomena and the design guidances of exhaust gas related structures on deck has been introduced. In future, parametric studies for the exhaust gas back flow factors will be carried out with the CFD analysis. The results of this study will be the guide for development of the prevention method of exhaust gas back flow phenomena for large container carriers.

• Journal of Navigation and Port Research
• /
• v.35 no.8
• /
• pp.613-618
• /
• 2011

Vessels on anchoring are sometimes dragged due to the increased external forces. For preventing the dragging, it is required to enhance the holding power of the anchor. The holding power depends on the type and weight of the anchor and the seabed condition. Especially, the holding power of AC-14 type anchor is known to be 2~2.5 times bigger than that of ASS type anchor. However, these coefficients was determined nearly by the result of the model test, so there is a need to verify that by sea trial. Therefore actual dragging case was analyzed and then compared with the coefficients in use, it was found that the two of them are much alike.

• Journal of the Society of Naval Architects of Korea
• /
• v.34 no.1
• /
• pp.50-59
• /
• 1997

Shipbuilder checks the status of main engine and propeller operation before sea trial. Generally these tests are carried out at a quay during fitting out of the ship. For these tests the operator has to estimate the maximum RPM with permissible torque and thrust to ensure the safety of the mooring line and ship. In this paper, the propeller characteristics according to the draft variation for a moored ship is inveatigated. From these tests, it is shown that shaft submergence is a dominant parameter in the propeller performance at shallow shaft submergence and that the propeller performance is dependent upon the propeller RPM when the shaft submergence is kept unchanged. In this study, a simple formula of the required thrust for a given propeller shaft submergence and propeller RPM is derived. 1be propeller thrust, which is calculated by another formula in case of dtep draft, is compared with results of bollard pull test for FPSO.

• Journal of Aquaculture
• /
• v.19 no.4
• /
• pp.254-260
• /
• 2006

A 6-week feeding trial was conducted to determine apparent protein and phosphorus digestibilities in order to evaluate nine different dietary protein sources in growing olive flounder, Paralichthys olivaceus. Nine diets containing fish meal analog ($BAIFA-M^{TM}$), white fish meal (WFM), flounder muscle powder (FMP), squid liver powder (SLP), leather meal (LM), soybean meal (SM), corn gluten meal (CGM), poultry by-product (PBP) or egg albumin(EA) were prepared by mixing a basal diet (BD) with one of nine test ingredients at the ratio of 7 to 3. Apparent protein digestibilities of FMP, SLP, WFM, SM, CGM, LM, PBP, $BAIFA-M^{TM}$, and EA were 94%, 92%, 86%, 82%, 75%, 72%, 72%, 71%, and 30%, respectively. Apparent phosphorus digestibilities of FMP, SLP, $BAIFA-M^{TM}$, LM, WFM, PBP, CGM, EA and SM were 77%, 72%, 65%, 55%, 54%, 50%, 20%, 20%, and 17%, respectively. Weight gain of fish fed FMP ($323^a$) was significantly higher than those of fish fed the other diets, and those of fish fed basal diet ($302^b$), SLP ($305^b$) and WFM ($308^b$) diet were significantly higher than those of fish fed SM ($274^c$), $BAIFA-M^{TM}\;(268^{cd}),\;PBP\;(261^{de}),\;LM\;(251^e),\;CGM\;(254^e)$ and EA ($181^f$). Based on the results of apparent protein digestibilities, apparent phosphorus digestibilities and weight gain, SLP, SM and $BAIFA-M^{TM}$ could be one of good protein source to replace fish meal in flounder diets.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.3
• /
• pp.164-173
• /
• 2014

In underwater robotics, vision would be a key element for recognition in underwater environments. However, due to turbidity an underwater optical camera is rarely available. An underwater imaging sonar, as an alternative, delivers low quality sonar images which are not stable and accurate enough to find out natural objects by image processing. For this, artificial landmarks based on the characteristics of ultrasonic waves and their recognition method by a shape matrix transformation were proposed and were proven in Part 1. But, this is not working properly in undulating and dynamically noisy sea-bottom. To solve this, we propose a framework providing a selection phase of likelihood candidates, a selection phase for final candidates, recognition phase and tracking phase in sequence images, where a particle filter based selection mechanism to eliminate fake candidates and a mean shift based tracking algorithm are also proposed. All 4 steps are running in parallel and real-time processing. The proposed framework is flexible to add and to modify internal algorithms. A pool test and sea trial are carried out to prove the performance, and detail analysis of experimental results are done. Information is obtained from tracking phase such as relative distance, bearing will be expected to be used for control and navigation of underwater robots.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.10
• /
• pp.16-22
• /
• 2020

The Korea Institute of Ocean Science & Technology is developing a free-fall cone penetration test system (FFCPT) that can acquire the characteristics of the seabed surface soil. To obtain the data through the FFCPT, a method of storing the signals for the entire time or a method of storing the signal for user-defined time can be considered. For efficient data storage and management, it is advantageous that data be stored by user definition. Therefore, this study analyzed the basic behavior using the signal acquired through a sensor mounted in the FFCPT and developed a trigger method to recognize the start and end of data storage using a depth sensor. The start and endpoints of the fall were determined using the moving average difference of 3 and 0.03 seconds of the depth signal. A real sea-trial test was performed using the FFCPT, and the developed trigger was operated normally.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.36 no.3
• /
• pp.166-174
• /
• 2000

Anchovy, EngrauEis japonica scoop nets are used in the coastal of Southern and Cheju of Korea. Especially in the Cheju, the fishing gear of scoop nets consists of upper boom, lower boom, pressing stick and bag net. They are operated by fishing boats of 6 to 10 ton class and 8 persons on board. The booms are controlled by side drum, and the net and pressing stick are hauled by only human power in operating. Therefore this fishery needs to large labor and heavy human power and has much risk. Three kinds of hydraulic winding device which controls two booms was designed and manufactured to reduce heavy labor force of scoop nets, and trial in the sea was carried out to test their performances using the commercial fishing boats of 6 ton class. The proper capacity of hydraulic pump and motor were determined by model test of boom 1/5 scale. The results obtained are as follows, 1. Tension of boom which is being drawn was the strongest and 187.5kgf when the boom's end is in the depth of 4m under the water. 2. The hydraulic motor of the fittest kind of winder has the least leakage per time than the other kinds. 3. In the best type of several winder devices, when the pressure difference was fixed $130kg/^2$ for the safe fishery, the winding velocity of boom line was 2m/sec, is faster 0.48/sec than traditional fishing method and this winder can catch the anchovy of 1.6 tonnage. 4. As a result, the crew were decreased from 8 to 6 and the problem of heavy human power and risk on fishing operation were solved by using the this winder.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.9 no.3
• /
• pp.148-153
• /
• 2006

This study dealt with the measurement of exhausted gas concentration, the estimation of a combustion efficiency, and the review of IMO indexing. We concentrated on establishing the basic data to take a counterplan coping with $CO_2$ regulations. The average combustion efficiency was 98% in shop test of new engines and 96.5% in sea trial test of new ships, respectively. It would become lower for the old engine or/and ship. High combustion efficiency results in high $CO_2$ emission and low combustion efficiency results in high emission of incomplete combustion products. The efficient method reducing $CO_2$ emission without an increase in noxious air pollutants would be the development of a substitute fuel and the fuel-efficient and economical engine, and the fair play among shipping agencies in a ship speed. In reviewing of IMO indexing, it is necessary to begin by analyzing the carbon content of a marine fuel for a precise estimates.