• Title/Summary/Keyword: Ocean resource

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Assessment of fishing power and fishing capacity of the snow crab (Chionoecetes opilio) gillnet fishery in the East Sea (동해안 대게 자망어업의 어획 성능 및 어획 능력 평가)

  • Lee, Kyoung-Hoon;Kim, Pyung-Kwan;Kim, Do-Hoon;An, Heui-Chun;Lee, Chun-Woo
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.48 no.1
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    • pp.29-39
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    • 2012
  • Currently, environment-friendly and sustainable fisheries are one of the major issues among fisheries authorities. A variety of alternative management policies and projects are going on to enhance fisheries management systems and fishery resources such as a TAC management program and a VDS (Vessel Day Scheme) management scheme for distant water fishing nations in Western and Central Pacific Fisheries Commission (WCPFC) convention area. These kinds of efforts among fisheries management authorities are aimed at limiting fishing capacity or fishing power. In terms of fisheries management, Fishing capacity and fishing power have increased the importance of the impact on a fishery and level of the resources. Increased fishing capacity and fishing power have caused not only depletion of fisheries resource, but also additional fishing cost. therefore, there is a clear need for authorities to manage fishing capacity and fishing power. It is also help ensure the conservation and sustainability of the fishery resources. Because of lack of data, absolute fishing power is difficulty to measure. The notion of relative fishing power is frequently used. In this study, relative fishing power was assessed using Mastuda (1991) method for fishing power index. The raw data for assessment was based on fishermen's logbook data from sampled fishing vessels in coastal snow crab gillnet fishery. Data Envelopment Analysis (DEA) method was used to assess fishing capacity. DEA is a linear programming methodology to measure the efficiency of a set of entities called Decision-Making Units (DMUs). It was recommended by FAO for assessing capacity in fisheries.

Analysis on Calcination of Cementitious Powder of Waste Concrete for Raw Cement

  • Park, Dong-Cheon;Kwon, Eun-Hee;Ahn, Jae-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.14 no.1
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    • pp.54-60
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    • 2014
  • The purpose of this study is to examine whether cementitious powder separated from waste concrete can be used as an alternative raw material to limestone and reduce the usage of natural resource (limestone) and $CO_2$ emission based on recycling cementitious powder from waste concrete. Experiments actually analyzed the chemical composition of cementitious powder and performed hyperthermia analysis, measurement of free CaO and XRD analysis to measure the degree of recovery of hydration in the model of cementitious powder manufactured based on chemical composition. These were performed in each cementitious powder model at different calcination temperatures such as $900^{\circ}C$, $1200^{\circ}C$, $1300^{\circ}C$, $1400^{\circ}C$ and $1450^{\circ}C$. Through the experiments, it was found that the recovery of hydration was at a level which can be used as the alternative raw material for limestone, but the replacement ratio was directly affected by the degree of mixing of fine aggregate in less than $150{\mu}m$, which cannot be separated from cementitious powder. It was shown that there was no difference in the production of compounds involved in hydration at calcination temperatures of $1200^{\circ}C$ or higher. Therefore, to pursue the replacement of limestone and reduction of greenhouse gas by recycling cementitious powder, the development of technology to efficiently separate aggregate fine powder is required.

Trends in Recovering Dissolved Boron from Wastewater and Seawater (폐수와 해수로부터 용존 붕소를 회수하는 연구동향)

  • Jung, Sungsu;Kim, Myung-Jin
    • Resources Recycling
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    • v.25 no.4
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    • pp.3-10
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    • 2016
  • A lot of researches have been carried out on the recovery of resources from the seawater all over the world. The boron concentration in seawater is low about at 4.5ppm, but considering the volume of seawater, the total weight of dissolved boron amounts to about 5.4 trillion tons. The boron is an essential resource in about 300 kinds of industries. Korea has imported all of the boron and spent more than 700 billion won each year. In this article, we introduce the domestic and international research trends and technologies for removing or recovering the boron from wastewater and seawater. Most of the researches have been conducted to remove the boron from the desalination process, and to recover the boron mainly from wastewater and brine. The technique for the recovery of the dissolved boron includes the ion exchange, which is the most representative, the adsorption membrane filtration (AMF), solvent extraction, and so on.

Estimating the biomass of anchovy species off the coast of Tongyeong and Yeosu in South Korea in the spring and winter of 2013 and 2014 (2013년-2014년 춘계와 동계에 대한 통영과 여수 연안역의 멸치 어군의 현존량 추정)

  • Kang, Myounghee;Seo, Young Il;Oh, Taeg Yun;Lee, Kyounghoon;Jang, Choong-Sik
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.51 no.1
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    • pp.86-93
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    • 2015
  • Anchovy (Engraulis japonicus) is one of the most important species in the South Sea of South Korea. In order to estimate the biomass of anchovy, acoustic surveys, concurrently with trawling, were conducted in April, July, and September of 2013 and February of 2014 off the coast of Tongyeong and Yeosu. However, anchovies were found only during spring (April) and winter (February) surveys. To display only anchovy species confirmed by trawls on empty spaced echograms, virtual echograms were created. Three target strength (TS) values of anchovy were used: TS_z = 20 log L - (20/3) log (1+z/10) - 67.6 (Zhao et al.), TS_y =20 log L - 72.9 (Yoon et al.), TS_f = 20 log L - 71.9 (Foote). For anchovy schools combined with other species e.g., hairtail, squid, and Korean pomfret, their TS values were used to calculate an average TS. As a result, the anchovy biomass in the winter survey was approximately 75,000 tons (TS_z), 90,000 tons (TS_f), 114,000 tons (TS_y), respectively. The biomass in spring was 9,000 tons (TS_z), 9,200 tons (TS_f), 10,000 tons (TS_y). The sampling variance of spring was 70% and of winter was 30%. In order to manage anchovy resource sustainably, larvae and adult anchovy should be separately surveyed, the optimal area, date, and time for acoustic survey should be investigated, and the biomass survey should be done for relatively long and regular base.

A study on indicators and reference points for the ecosystem-based resource assessment (생태계 기반 자원평가를 위한 지표와 기준점 연구)

  • Zhang, Chang-Ik;Park, Hee-Won;Lim, Jung-Hyun;Kwon, Hyeok-Chan;Kim, Doo-Hoon
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.46 no.1
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    • pp.32-49
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    • 2010
  • Ecosystem-based fisheries management requires a holistic assessment of the status of fisheries by integrating fishery ecosystem indicators for management objectives. In this study four objectives were identified such as the maintenance of the sustainability, biodiversity and habitat quality and socio-economic benefits. The ecosystem-based fisheries assessment (EBFA) model to assess fisheries and their resources at the ecosystem level developed for Korean fisheries (Zhang et al., 2009) has a number of indicators for three management objectives. However, it was found that there were some overlapping components among indicators and that there were difficulties in assessing some indicators in the EBFA model. This study identified problems of the approach and suggested more pragmatic and simpler indicators. It also presented alternative reference points to assess indicators and discussed issues associated with the application of the EBFA model to a marine ranching ecosystem. In this study a total of 24 indicators were used for the assessment which included 4 socio-economic indicators. New indicators and reference points were demonstrated by applying it to the Uljin marine ranch.

Earthquake Response Characteristics of a Port Structure According to Exciting Frequency Components of Earthquakes (가진 주파수성분에 따른 항만구조물의 지진응답특성에 관한 연구)

  • Kim Doo Kie;Ryu Hee Ryong;Seo Hyeong Yeol;Chang Seong Kyu
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.17 no.1
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    • pp.41-46
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    • 2005
  • The seismic response characteristics of a port structure were investigated by the earthquake analyses of the structure subjected to high-, low-frequency component, and Uljin earthquakes. In the Fluid-Structure-Soil Interaction(FSSI) analysis, the fluid is modeled by the 4-node quadrilateral element which is a modification of a structural plane element, and the port structure and foundation is modelled by the plane strain element. Since the present method directly models the fluid-structure-soil interaction system using finite element method, it can be easily applied to the dynamic analysis of a 2-D fluid-port-soil system with complex geometry. The results of the seismic coefficient. added mass, and FSSI methods are compared. The results showed that the earthquake with high frequency components more affects the seismic response of the structure than that of low frequency components.

Fishing characters of skate ray, Raja pulchra by the offshore longline fishery in Heuksan-do, Korea (흑산도 근해연승어업의 참홍어 (Raja pulchra) 어획 특성)

  • Jo, Hyun-Su;Hwang, Hak-Jin;Kwon, Dae-Hyeon;Jeong, Gyeong-Suk;Choi, Kang-Ho;Cha, Byung-Yeul;Im, Yang-Jae
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.47 no.4
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    • pp.403-410
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    • 2011
  • Catches, CPUE, fishing season, disc width composition and fishing ground were studied to rebuild skate ray, Raja pulchra resource by the offshore longline fishery in Heuksan-do, Korea. Annual catches and CPUE of skate ray were increased from 2003 to 2010 (CPUE: from 2007 to 2010) continuously. The main fishing season of the skate ray was from December to next May. Disc width at 50% maturity for Raja pulchra by sex were estimated to be 65.83cm, 57.01cm by female and male respectively. The range of disc width was 22.3-112.0cm and the average disc width was 66.9cm, 60.0cm by female and male of Raja pulchra respectively during 2007-2010. Annual average of disc width of female skate ray was decreased from 2007 to 2010. The fishing grounds were formed from the coastal water off Hong-do to the coastal water off Gyeogyeolbiyeol-do, Korea. The center of fishing ground in October was formed in the northwestern coastal water off Gyeogyeolbiyeol-do and separated from that of the other months.

Catch variation of a set net fishing ground in the coastal waters off Neungpo, Goeje Island (거제도 능포 정치망 어장의 어획물과 어획량 변동요인)

  • Cha, Byung-Yul
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.45 no.4
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    • pp.211-222
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    • 2009
  • The fisheries resources by a set net in the coastal waters off Neungpo, Goeje Island from 2003 to 2004 were studied to determine species composition and catch variation. The main fishing period by a set net were from April to December in 2003 and from May to December in 2004. A total weight of 48 species caught through the survey period was 540,688.0kg. Most of them were 44 species of fishes and a few were 4 species of cephalopods. Dominant species was Trachurus japonicus accounting to 57.5% in total catch. Sub-dominant species were Trichiurus lepturus(12.9%), Engraulis japonicus(10.6%), Scomber japonicus(6.9%), Clupea pallasii(4.5%), Todarodes pacificus(2.8%) and Parapristipoma trilineaturm(1.3%). The remnant species showed a low catch, indicating the catch had less than 1% in total, respectively. T. japonicus and T. lepturus were caught throughout the survey period, but C. pallasii, Gadus macrocephalus, Oncorhynchus keta in low temperature season and Thunnus obesus in high temperature season. The fishing ground temperature was 11.7-24.0${^{\circ}C}$ in range and the catch by a set net was higher in autumn than in spring and in summer with the variation of fishing ground temperature. The annual catch by a set net was much higher in 2004 than in 2003 due to high temperature(>17${^{\circ}C}$) and the recruitment of T. japonicus from offshore seas. Therefore we concluded that the catch of Neungpo fishing ground by a set net was highly related to the variation of T. japonicus catch with fishing ground temperature.

A Study on the Structure and Origin of the Dokdo and it's Surroundings in the East Sea (Japan Sea) Using Magnetic Anomalies (지자기이상을 이용한 동해 독도 및 독도주변의 구조와 성인에 관한 고찰)

  • Kim, Chang-Hwan;Park, Chan-Hong;Min, Kyung-Duck;Han, Hyun-Chul;Kwon, Moon-Sang;Shim, Jae-Seol;Choi, Sung-Ho;Oh, Soon-Bock
    • Ocean and Polar Research
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    • v.24 no.4
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    • pp.491-500
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    • 2002
  • Magnetic anomalies in the Dokdo and it's surroundings were investigated with respect to structure and origin of the Dokdo and surrounding seamounts. After normal and diurnal correction of measured magnetic data, crossover correction was applied to reduce errors between sets of magnetic anomalies. The errors from crossover operation result in decrease of about 51%, from 62.2 nT to 30.1 nT in standard deviation. Reduction-to-the-pole, second vertical derivative and analytic signal processing were applied to explore magnetic anomaly signatures in detail. Magnetic anomalies are most complicated in the 1st-Dok seamount, show SWW-NEE linear pattern in the 2nd-Dok seamount and lower to the 3rd-Dok seamount. Different magnetic anomaly patterns in three seamounts imply that three volcanic seamounts were formed at different times and are composed of rocks that were produced in different conditions. It seems that the 3rd-Dok seamount was first to form and followed by the 1st-Dok seamount. The complicated magnetic and second vertical derivative anomaly patterns in the 1st-Dok seamount may be due to subsidiary cones around crater or the presence of intruded magma bodies below sea surface and the Dokdo is probably a marginal subsidiary part of crater.

Swimming pattern analysis of a Diving beetle for Aquatic Locomotion Applying to Articulated Underwater Robots (다관절 유영로봇에 적용하기 위한 물방개의 유영패턴 분석)

  • Kim, Hee-Joong;Lee, Ji-Hong
    • The Journal of Korea Robotics Society
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    • v.7 no.4
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    • pp.259-266
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    • 2012
  • In these days, researches about underwater robots have been actively in progress for the purposes of ocean detection and resource exploration. Unlike general underwater robots such as ROV(Remotely Operated Vehicle) and AUV(Autonomous Underwater Vehicle) which have propellers, an articulated underwater robot which is called Crabster has been being developed in KORDI(Korea Ocean Research & Development Institute) with many cooperation organizations since 2010. The robot is expected to be able to walk and swim under the sea with its legs. Among many researching fields of this project, we are focusing on a swimming section. In order to find effective swimming locomotion for the robot, we approached this subject in terms of Biomimetics. As a model of optimized swimming organism in nature, diving beetles were chosen. In the paper, swimming motions of diving beetles were analyzed in viewpoint of robotics for applying them into the swimming motion of the robot. After modeling the kinematics of diving beetle through robotics engineering technique, we obtained swimming patterns of the one of living diving beetles, and then compared them with calculated optimal swimming patterns of a robot leg. As the first trial to compare the locomotion data of legs of the diving beetle with a robot leg, we have sorted two representative swimming patterns such as forwarding and turning. Experimental environment has been set up to get the motion data of diving beetles. The experimental equipment consists of a transparent aquarium and a high speed camera. Various swimming motions of diving beetles were recorded with the camera. After classifying swimming patterns of the diving beetle, we can get angular data of each joint on hind legs by image processing software, Image J. The data were applied to an optimized algorithm for swimming of a robot leg which was designed by robotics engineering technique. Through this procedure, simulated results which show trajectories of a robot leg were compared with trajectories of a leg of a diving beetle in desired directions. As a result, we confirmed considerable similarity in the result of trajectory and joint angles comparison.