• Journal of the Korean Society of Marine Environment & Safety
• /
• v.15 no.1
• /
• pp.25-32
• /
• 2009

The burial method has been generally used for the protection methods of submarine cable. Especially in Korea, various types of protection methods have been used according to fisheries and fishing implements. In these days, all the protection methods - burial, continuous concrete mattress, cast iron pipes, U-duct, concrete bags, rock berm, mortar bags and FCM(Flexible Concrete Mattress) are applied to the submarine cable, but these methods just focus not on the characteristics of ocean environment and the protection of environment but on the safety of submarine cable against the external damages. This research presents the protection methods of submarine cable according as the characteristics of ocean environment - external damages, depth of water, seabed condition and the protection of environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.49 no.1
• /
• pp.18-28
• /
• 2013

It was compared the estimated parameters by the surplus production from three different models, i.e., three types (Schaefer, Gulland, and Schnute) of the traditional surplus production models, a stock production model incorporating covariates (ASPIC) model and a maximum entropy (ME) model. We also evaluated the performance of models in the estimation of their parameters. The maximum sustainable yield (MSY) of small yellow croaker (Pseudosciaena polyactis) in Korean waters ranged from 35,061 metric tons (mt) by Gulland model to 44,844mt by ME model, and fishing effort at MSY ($f_{MSY}$) ranged from 262,188hauls by Schnute model to 355,200hauls by ME model. The lowest root mean square error (RMSE) for small yellow croaker was obtained from the Gulland surplus production model, while the highest RMSE was from Schnute model. However, the highest coefficient of determination ($R^2$) was from the ME model, but the ASPIC model yielded the lowest coefficient. On the other hand, the MSY of Kapenta (Limnothrissa miodon) ranged from 16,880 mt by ASPIC model to 25,373mt by ME model, and $f_{MSY}$, from 94,580hauls by ASPIC model to 225,490hauls by Schnute model. In this case, both the lowest root mean square error (RMSE) and the highest coefficient of determination ($R^2$) were obtained from the ME model, which showed relatively better fits of data to the model, indicating that the ME model is statistically more stable and robust than other models. Moreover, the ME model could provide additional ecologically useful parameters such as, biomass at MSY ($B_{MSY}$), carrying capacity of the population (K), catchability coefficient (q) and the intrinsic rate of population growth (r).

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.59 no.3
• /
• pp.261-263
• /
• 2023

Recently, universities of fisheries and institutions related to fisheries are actively carrying out a project to build new fisheries training ships. These new fisheries training ships are significantly larger in size and longer in length than the previous ships. In addition, these new ships basically have space that can accommodate more than 100 crew and passenger. On the other hand, they are excluded from IMO maneuverability evaluation since the size of these ships are still less than 100 m in length (LBP). These results have had an impact on the study of maneuverability of fishing vessels including the fisheries training ships. Against these backgrounds, the authors conducted a study to estimate the maneuvering characteristics of fisheries training ship Baek-Kyung according to depth in order to prepare a maneuvering characteristic index that enables the large fisheries training ships to navigate more safely using a modified empirical formula. It was confirmed that the maneuvering characteristics of Baek-Kyung changed significantly as the values of the hydrodynamic force coefficients changed as the water depth gradually decreased from around 1.5 (approx. 8 m in depth) of the ratio of the water depth to the ship draft. The results of this study will not only help navigators understand the maneuvering characteristics of Baek-Kyung, but also serve as an indicator when navigating in shallow water. In addition, the accumulation of these results will serve as a basis for future study on maneuverability of fishing vessel types.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.25 no.3
• /
• pp.111-123
• /
• 1997

In order to understand the spatial forms of stream, this study aimed to typify stream microtopography through the collection of common names of topography determined by fishermen and to describe stream landscapes by using these typology. The seventeen stream microtopography names were sorted out and divided into three types : the streamside space which includes Kaeul-jari, Hapsu-mori, Cholpyok-jidae, Kyekok-jidae and Korpuri, stream plate which includes Youl, Mulgol, So and Ungdongi, and streambed materials which includes Ampan-jidae, Pawi-jidae, Dolpat-jidae, Chagal-jidae, Chanchgal-jidae, Moraetop, Kamtang-padak and Suchodae. The spatial characteristics of stream microtopography landscape were described according to the comparison of landform, the support of fishing, accessibility, viewpoint and eye-catching degree. The tipification of stream microtopography and their symbolization will offer a rich vocabulary to describe diverse spatial forms of stream.

• The Journal of Fisheries Business Administration
• /
• v.40 no.3
• /
• pp.29-49
• /
• 2009

There are various types of predictable economic benefits to restoring beneficial uses from contaminated marine sediment cleanup. These benefits can be derived from reduction in aquatic animals died or infected, increase in their consumption recovery, increase in tourism including recreational fishing, reduction in human health risk, increase in amenity and aesthetics, increase in ecosystem integrity, and so on. The paper focuses on estimating the net increase in value for producers and consumers from producing and consuming those fish due to the pollution reduction of marine contaminated cleanup project. Almost Ideal Demand System(AIDS) is employed for estimate of the demand for fish, and the production cost function for fish are determined using market data. The result shows 10.8 billion won per year for economic surplus to the net increase for producers and consumers.

• Journal of the Korean Institute of Navigation
• /
• v.25 no.4
• /
• pp.407-415
• /
• 2001

In the present study, irregular disturbances to ship dynamics is proposed, where irregular disturbances implying irregular wave and the fluctuating component of wind for the evaluation of automatic steering system of ship in following seas. Prediction method based on the principle of linear superposition. Irregular wave disturbances in following seas is calculated by frequency variation method. The mathematical model of each element of an automatic steering system is derived, which takes account of a few non-linear mechanisms. PD(Proportional-Derivative) controller and low-pass filter with a weather adjustment are adopted to modelling the characteristics of an autopilot. Performance index is introduced from the viewpoint of energy saving, which derived from the concept of energy loss on ship propulsion. Finally, the present methods are applied to two typical types of ship ; an ore carrier and a fishing boat. The various effects of control constants of autopilot on propulsive energy loss are investigated

• Solar Energy
• /
• v.20 no.4
• /
• pp.9-16
• /
• 2000

This paper represents the heat storage performance of the flat plate solar collector. This research aims to application for fishing ship on the sea, and the solar collector has among of motions with pitching and rolling thus, this collector has to be a forced type circulation. In this research, we investigated the solar collector performance for the various collector tilt angle. As the experimental results with three types, we found that the S-type collector was excellent.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.5
• /
• pp.614-621
• /
• 2007

The fishing boat propulsion system employing the modified stern shape and the tunnel to protect a propeller is developed to increase the cruise speed and reduce he problem resulting from the open propeller accidentally catching the waste net and able on the sea. Using 3 different tunnel types, the model test was performed in the circular water channel and the panel method based on the potential theory is applied to analyze the open water performance of the propeller. In the numerical analysis using he potential-based panel method, it calculates the hydrodynamic interaction between the propeller and the tunnel and evaluates the effect of the tunnel geometry. From the numerical and experimental results differing tunnel geometries, the propulsion efficiency is increased by the larger diameter of the inlet than the outlet of the tunnel and the smaller gap between the propeller tip and the tunnel internal surface. These results provide the information of the propeller system with the tunnel and the hydrodynamic interaction between the propeller and the tunnel.

• Journal of Korea Ship Safrty Technology Authority
• /
• s.24
• /
• pp.4-20
• /
• 2008

Stainless steel 304 or stainless steel 630 types using propeller shaft of a small ship or a FRP fishing boat generally restrain localization corrosion and abrasion damage occurrence to shaft bearing or grand packing contact. In general, the residual stress which remains after welding or heat treatment in material can cause the stress concentration or localization corrosion. In case of small ship, stainless steel such as STS304 has long been used for propeller shaft. Meanwhile, crew of small ship tend to reuse damaged propeller shaft after repair by welding and performing heat treatment to save cost. However, it was found that reused propeller shaft by repair often caused troubles in ship's operation. In this study, the basic guideline for maintenance and treatment of propeller shaft are investigated. From the results of investigation, remarkable deterioration of the material properties and corrosion resistance on the welded work part was observed.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.5
• /
• pp.324-332
• /
• 2018

It is known that damages to the subsea cables used for electric power transmission between islands and countries, including renewable energy from offshore wind power, current, tides, etc., cost much to restore, which causes social and economic losses. Various types of fishing rigs and anchors have been reported to be the greatest hazards to subsea cables. It is possible to design and construct a suitable protection facility for a subsea cable by precisely estimating the underwater behavior of such hazardous apparatuses. In this study, numerical simulations of the underwater behaviors of various hazardous apparatuses were carried out using fluid-structure interaction (FSI) analysis as a basic study to simulate the actual behavior phenomena of hazardous apparatuses in relation to a subsea cable. In addition, the underwater drop characteristics according to the types of hazardous apparatuses were compared. In order to verify the accuracy of the FSI analysis method used in this study, we compared the test results for underwater drops of a steel ball bearing. Stock anchors, stockless anchors, and rocket piles, which were actually reported to be the cases of damage to subsea cables along the southwest coast of Korea, were considered as the hazardous apparatuses for the numerical simulations. Each hazardous apparatus was generated by a Lagrangian model and coupled with the fluid domain idealized by the Eulerian equation to construct the three-dimensional FSI analysis model. The accuracy of the numerical simulation results was verified by comparing them with the analytical solutions, and the underwater drop characteristics according to the types of hazard apparatuses were compared.