• Journal of Korean Port Research
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• v.15 no.1
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• pp.75-85
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• 2001

Accuracy of dredging processes depends on the types of equipment used, the sediments encountered, whether the work to be performed is new or maintenance dredging, pre- and post-hydrographic surveying and so forth. Among those, position surveying accuracy which is directly determined by the control of the dredge's position and depth surveying accuracy being surveyed at the dredging point during dredging work are important factors. The purpose of this study is to develop 'Dredge Management System'for Grab dredge which is composed of 4 sub-system using LADGPS for dredge position determining system and dredging point determining system, tide gauge system and optical sensor for depth determining system and GIS and ENC for total management system. This system is installed on the grab dredge 'EUNJIN G-18'and applied to anchorage dredging work. at Pohang Harbor. The results revealed that this system is easy to operate, achieves good accuracy with only 45cm unevenness, reduces working period by 22 percent and saves cost 16.6 percent.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.530-541
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• 2014

The dredge gear is dragged along the bottom of the sea to catch targeted edible bottom dwelling species. Species composition and ecological index of the catches of dredge were estimated around Gangneung coastal fishing ground by dredge with different mesh size and tooth space from July to December 2013. Eight different types of dredge including four different tooth space (24.7 mm, 29.9 mm, 34.9 mm, 40.1 mm) and four different mesh size(15.5 mm, 32.7 mm, 51.1 mm, 60.0 mm) were used in the experiment. During the experiment, total catches were collected 31 species as sipunculida 1 species, mollusca 13 species, annelida 3 species, arthropoda 8 species, echinodermata 4 species and others 2 species. The dominant genus were mollusca and echinodermata while the dominant species were Megangulus venulosus, Pseudocardium sachalinensis, Schaphechinus brevis. The richness index was ranged 1.29-1.72, evenness index was 0.6-0.65 and diversity index was 1.65-1.83 according to the tooth space and mesh size of dredge. Richness index, diversity index were high at tooth space 34.9 mm dredge and ecological index showed decreasing tendency with the increasing of mesh size of dredge. Cluster and MDS analysis, based on a Bray-Curtis and similarity matrix of fourth root transformed data of number of species and wet weight, showed division into four different groups as four different tooth space (Group A), four different mesh size Group B (51.1 mm, 60.0 mm), Group C (32.7 mm) and Group D (15.5 mm).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.613-620
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• 2011

In order to perform scientific evaluation of dredge results, it is needed to construct the system which is able to manage and evaluate the work process by monitoring in real-time the dredge process such as dredge ship position, dredge depth and dredge volume. This research aims to develop the hydrographic dredge surveying system adding water depth measurement method to both precise positioning and navigation methods using GPS, which allows a high rate of measurement and long distances between the control point and dredging points, operate in all weather conditions, and does not require line of sight to points. We constructed Beacon DGPS-based hydrographic dredger guidance and position management system and developed the operation program which makes the dredge operation perform as monitoring work situation in real-time. It is expected that this developed system will be able to contributes to reducing ultimately the cost in hydrographic dredging or hydrographic construction industries.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.327-336
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• 2017

Fishing dredge in Jeollabuk-do began to become widespread in the 1960s and has continued to catch diverse kinds of shellfish in the productive fishing grounds around Dongjin River, Mangyeong River and Geum River estuaries. Since the 1970s, the construction of various large-scale industrial complex and the implementation of Saemangeum reclamation project have resulted in a decrease in main fishing areas and a sharp decline in shellfish production. As a result, dredge fishery has faced many difficulties. Dredge fishery in Jeollabuk-do is carried out with a total of 30 fishing permits as of 2016. Surf clams, hen clams, bladder moon snails, and common orient clams were mainly caught before the construction of Saemangeum dike while comb pen shells, purple whelks and ark shells are mainly caught afterwards. Inside the Saemangeum dike, most fish species have disappeared due to low water level and low salinity, and littleneck clams are caught using a jet pump type of fishing dredge. Outside the dike, the diversity of shellfish species has been reduced; comb pen shells are mainly caught. In this process, a lot of friction occurs due to the use of a reformatted dredge. Therefore, a lot of research needs to be conducted in the near future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.6
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• pp.708-719
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• 1995

This study is to estimate abundance of the Chesapeake Bay blue crab stock. Using 823 dredge tows which were conducted during the 1991 winter survey, blue crab abundance was estimated on the basis of newly developed methods which account for unequal dredge tow distances, size- and sex-specific heterogeneous overwintering spatial distributions, wintertime exploitation, the time period of quasi-hibernation, and dredge capture efficiency. The estimate of total abundance before correction by gear efficiency was 131.8 million crabs $(95\%\;C.I.\;=\;118.2\;million\;crabs\;to\;145.4\;million\;crabs),$ Dredge capture efficiency was estimated to be 0.474. Thus, the estimate of total abundance was calculated as 278.1 million crabs after correction by the efficiency factor.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.369-379
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• 1993

Using a successive removal approach the mechanism of sampling capture efficiency of blue crabs by dredges was studied in Chesapeake Bay during winter 1992. For the twenty-six field experiments no significant statistical differences were detected in dredge efficiency using general linear model analysis by factors including bottom sediments, water depths, and sampling vessels. Dredge efficiency (i.e., catchability) was estimated by two methods, Leslie (Leslie and Davis, 1939) and a simple revised method. Mean catchability was estimated at 0.26 (SE=0.03), indicating that only $26\%$($95\%\;C. I.=20{\sim}32\%$) of crabs present in the path of the dredge of a given sampling area are caught with a single dredge tow. Dredge efficiency declined exponentially as crab density increased.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.146-151
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• 2002

Efficiency of dredging work depends on the types of equipment used, the sediments encountered, whether the work to be performed is new or for maintenance, pre and/or post hydrographic surveying and so forth. Among those, surveying accuracy which is directly determined by the control of the dredge's position and depth surveying accuracy being surveyed at the dredging point are important factors. The purpose of this study is to develop an integrated process management system for pump dredge. The system is composed of 4 sub-systems such as LADGPS for dredge positioning dredging point determination, tidal gauge and angular depth sensor for depth determination, and GIS and ENC process management. The process management system for pump dredge developed was installed on the pump dredge "EUNJIN PD-2" but is now producing work data for comparison with performance of the existing dredge. The data retrieved from the pump dredge process management system up to now shows similar result from the grab dredge management system which was developed previously. It is easy to operate, achieves good accuracy with only 45cm unevenness, reduces working perioa by 20 percint,. More precise evaluation of the system comes later after the dredging work is completed.completed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.285-294
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• 2003

To select an appropriate sampler for the environmental monitoring survey in coastal waters of Saemangeum, Jeollabuk-do, a macrobenthic sampling was conducted in April 2002. Employed samplers were dredge (type Charcot), a semi-quantitative sampler and Smith-McIntyre (SM) and van Veen grab (VV) as quantitative ones. One haul was tried for dredge and 3 replicates (0.1 ㎡${\times}$3) for SM and W at each of 11 stations. Comparisons of sediment volume in sampler bucket and of precision of biological parameters (i.e., density, biomass, species number and diversity index, H') were made between SM and VV. Sediment volume was significantly different (SM > VV) at p-value of 0.0050 (paired t-test) and, in average, 3 replicate samples of SM and VV satisfied a precision level of 0.2 by applying 4th root transformation. Patterns of observed and expected species numbers and H' were compared. Dredge-VV samples showed higher affinity than any other pair. Several dominant species in the area were underestimated in dredge samples (e.g., polychaete Heteromastus filiformis. Aricidea assimilis etc.). Quantifying the agreement pattern of multi-species responses was accomplished by estimating correlations between similarity matrices. Correlation between dredge and VV was slightly higher, but near-per-fect matches were found in general. Different ranks and composition among principal species lists were presumably linked to the effect of penetration depth that differs among samplers. Lower level of some species' abundance in VV samples (ca. 50％ compared with those of SM) was explained in this context. It seem appropriate to regard the effect as a probable cause of relatively higher correlations in dredge-VV, Overall bio-logica1 features indicated that a better choice could be SM in situations of requiring high data quality. The others work well, however, on observing and defining faunal characteristics and their capability cannot be questionted if we do not expect a first-order quality.

• Water Engineering Research
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• v.1 no.2
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• pp.137-146
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• 2000

A windows-based software package, named DREDGE, is developed for estimating sediment resuspension and contaminant release during dredging operations. DREDGE allows user to enter the necessary dredge information, site characteristics, operational data, and contaminant characteristics, then calculates an array of concentration using the given values. The program mainly consists of the near-field models, which are obtained empirically, for estimating sediment resuspension and the far-field models, which are obtained analytically, for suspended sediment transport. A linear equilibrium partitioning approach is applied to estimate particulate and dissolved contaminant concentrations. This software package which requires only a minimal amount of data consists of three components; user input, tabular output, and graphical output. Combining the near-field and far-field models into a user-friendly windows-based computer program can greatly save dredge operator's, planners', and regulators' efforts for estimating sediment transports and contaminant distribution.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.493-503
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• 2015

Species composition and bycatch rate of the catches by dredge with bycatch reduction device to reduce bycatch were estimated around Yeongil Bay, Korea at June, 2015. Total catches were collected 31 species as Chordata 10 species, mollusca 8 species, arthropoda 6 species, echinodermata 5 species, sipunculida 1 species, annelida 1 species during the experiment at the Yeongil Bay. The dominant species were Scapharca broughtonii, Callithaca adamsi, and Atrina pectinata and they reached 79.9% of the total catch. The catch rate of Scapharca broughtonii and Callithaca adamsi was 69.6% and 10.4% respectively. The rate of bycatch was 20.1%, consisted with Echinodemata 13.0%, Chordata 3.6%. The catch of ordinary dredge was 27 species 1,307 number 85,052g and that of dredge with escapement device was 21 species 1,690 number 91,648g. In conclusion, the dredge gear with bycatch reduction device has higher catch rate of target species and lower bycatch rate to non-target species than ordinary one.