• Title/Summary/Keyword: Marine products-marine

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Forecasting the Wholesale Price of Farmed Olive Flounder Paralichthys olivaceus Using LSTM and GRU Models (LSTM (Long-short Term Memory)과 GRU (Gated Recurrent Units) 모델을 활용한 양식산 넙치 도매가격 예측 연구)

  • Ga-hyun Lee;Do-Hoon Kim
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.56 no.2
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    • pp.243-252
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    • 2023
  • Fluctuations in the price of aquaculture products have recently intensified. In particular, wholesale price fluctuations are adversely affecting consumers. Therefore, there is an emerging need for a study on forecasting the wholesale price of aquaculture products. The present study forecasted the wholesale price of olive flounder Paralichthys olivaceus, a representative farmed fish species in Korea, by constructing multivariate long-short term memory (LSTM) and gated recurrent unit (GRU) models. These deep learning models have recently been proven to be effective for forecasting in various fields. A total of 191 monthly data obtained for 17 variables were used to train and test the models. The results showed that the mean average percent error of LSTM and GRU models were 2.19% and 2.68%, respectively.

Development of Copper Corrosion Products and Relation between Surface Appearance and Corrosion Rate

  • Tran, Thi Ngoc Lan;Nguyen, Thi Thanh Binh;Nguyen, Nhi Tru;Yoshino, Tsujino;Yasuki, Maeda
    • Corrosion Science and Technology
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    • v.7 no.2
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    • pp.99-111
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    • 2008
  • Copper was exposed unsheltered and sheltered in four humid tropical sites, representing urban, urban-industrial, urban-marine and rural environments. The corrosion rates and the sequence of corrosion product formation are presented and discussed in relation with climatic and atmospheric pollution parameters. Chemical compositions of corrosion products were found to depend on environments and duration of exposure. In all environments, cuprite was the predominating corrosion product that formed first and continuously increased during the exposure. Among the sulphur-containing corrosion products, posnjakite and brochantite were more frequently found and the first formed earlier. Nantokite was the most common chlorine-containing products for most cases, except the high-chloride environment, where atacamite was detected instead. The corrosion rate of copper was well indicated by the colour of patina. The red-purple colour corresponded to the high corrosion rate and the greenish grey colour corresponded to the low corrosion rate. Corrosion rate of sheltered copper in urban-marine environment increased with the exposure time.

Antioxidant Activity of (8E,13Z,20Z)-Strobilinin/(7E,13Z,20Z)-Felixinin from a Marine Sponge Psammocinia sp.

  • Jiang, Ya-Hong;Ryu, Seung-Hee;Ahn, Eun-Young;You, Song;Lee, Burm-Jong;Jung, Jee-H;Kim, Dong-Kyoo
    • Natural Product Sciences
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    • v.10 no.6
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    • pp.272-276
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    • 2004
  • During the course of our screening for bioactive metabolites from marine sponges, EZZ, the inseparable 1:1 mixture of (8E,13Z,20Z)-strobilinin and (7E,13Z,20Z)-felixinin has been found to deliver significant cytotoxicity against some cancer cell lines. In this study, the antioxidant activity of EZZ was first time evaluated by a series of antioxidant assays. It was found that EZZ was weak in scavenging the stable free radical 1,1-diphenyl-2-picrylhyrazyl (DPPH), but it was comparable to ascorbic acid in scavenging ABTS and superoxide radicals. In addition, EZZ could protect DNA from hydroxyl radical-induced strand cleavage. The findings of the present study suggest that EZZ possess certain antioxidant activity, which might help to prevent occurrence of cancer by alleviating the oxidative stress in cells.

The Study on the Reorganization of the Large Purse Seine Fisheries in Korea (대형선망어업의 생산력 재편과 경영 개선 과제)

  • KIM, Dae-Young
    • Journal of Fisheries and Marine Sciences Education
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    • v.21 no.3
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    • pp.373-389
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    • 2009
  • The aims of this study are to examine urgent problems for reorganization into future-proof large purse seine fisheries in order to positively cope with rapidly changing domestic and foreign fisheries circumstances. First, this paper provides current situations of the large purse seine fisheries. The current situations of it are composed of fisheries influence such as vessel number, vessel power, and fisher number, use of resource and fishing places, and changes in products and sales of species caught by the large purse seine. Secondly, this paper reviews current problems of the large purse seine fisheries including cost reduction and increase of value added. Thirdly, this paper suggests basic development direction and countermeasures for strengthening competitiveness of the large purse seine fisheries. In conclusion, urgent problems of the larger purse seine fisheries can be summarized as inefficiency of distribution structures and retarded landing system and facilities as well as the worse of profitability according to shrink of fishing places, reduction of products, lack of workers, and increase in oil price. To solve the urgent problems, the large purse seine fisheries should be changed into an industry with low cost and high efficiency, and also need to introduce of new production system, strengthen autonomous management of natural resource, and increase in value added to products.

Mineral Content and Nutritional Evaluation of Marine Invertebrates from the Korean Coast (한국 연안산 해산 무척추동물의 미네랄 함량과 영양평가)

  • Mok, Jong-Soo;Lee, Doo-Seog;Shim, Kil-Bo;Yoon, Ho-Dong
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.42 no.2
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    • pp.93-103
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    • 2009
  • To measure the mineral contents of marine invertebrates, we collected 239 individuals from 52 species from the east (Pohang), west (Gunsan), and south (Tongyeong) coasts of Korea: 34 species of molluscan shellfish (Gastropoda and Bivalvia), 6 species of Cephalopoda, 8 species of Crustacea, and 4 other species. The mean contents of the macro mineral in the 100g edible portion of molluscan shellfish were high in the oder of Na (355.1 mg), P (128.1 mg), K (110.8 mg), Mg (83.8 mg) and Ca (57.5 mg). And the mean contents of the micro mineral in the molluscan shellfish were high in the oder of Fe ($41.12{\mu}g/g$), Zn ($30.48{\mu}g/g$), Mn ($3.81{\mu}g/g$), Cu ($3.49{\mu}g/g$) and Ni ($0.35{\mu}g/g$). We could not observe clear regional variation in the mineral content of the molluscan shellfish species. The mean contents of the macro mineral in the 100g edible portion of other marine invertebrates (Cephalopoda, Crustacea, etc.) were high in the oder of Na (400.7 mg), P (145.1 mg), K (105.0 mg), Mg (63.2 mg) and Ca (49.0 mg). And the mean contents of the micro mineral in other marine invertebrates were high in the oder of Zn ($24.4{\mu}g/g$), Fe ($13.8{\mu}g/g$), Cu ($4.88{\mu}g/g$), Mn ($2.14{\mu}g/g$) and Ni ($0.12{\mu}g/g$). The daily average intakes of the macro mineral through fisheries products consisted of P (125.9 mg), Na (119.3 mg), K (101.8 mg), Ca (31.0 mg), Mg (27.6 mg). And the daily average intakes of the micro mineral through fisheries products consisted of Zn (0.92 mg), Fe (0.68 mg), Cu (0.12 mg) and Mn (0.07 mg). The respective intakes of the minerals (P, Mg, Na, Ca, K) from fish were about 18.0, 7.9, 8.0, 4.4 and 2.2% of the dietary reference intakes for Koreans (KDRIs) set by the Korean Nutrition Society. And the respective intakes of micro mineral (Cu, Zn, Fe, Mn) from fish were about 14.6, 9.2, 6.7, and 2.1% of the dietary reference intakes for Koreans (KDRIs). Therefore, fisheries products play a very important role as a source of mineral.

Effect of Hydrogen(H2) Addition on Flame Shape and Combustion Products in Mixed Coflow Diffusion Flames of Methane(CH4), Ethane(C2H6) and Propane(C3H8) (동축류 메탄(CH4), 에탄(C2H6), 프로판(C3H8) 혼합 확산화염내의 수소(H2) 첨가가 화염 형상 및 연소 생성물에 미치는 영향)

  • Park, Ho-Yong;Yoon, Sung-Hwan;Rho, Beom-Seok;Lee, Won-Ju;Choi, Jae-Hyuk
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.780-787
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    • 2019
  • As a carbon-free, green growth alternative, internal and external interest in hydrogen energy and technology is growing. Hydrogen was added to co-axial methane, methane-propane, and methane-propane-ethane diffusion flames, which are the main ingredients of LNG, to evaluate its effect on flame formation and combustion products. The variation in combustion products produced by adding hydrogen gradually to diffusion pyrolysis at room temperature and normal pressure conditions was observed experimentally by using a gas analyzer, and the shape of diffusion pyrolysis was observed step by step using a digital camera. The experimental results showed that the production volume of nitrogen oxides tended to increase and became close to linear as hydrogen was added to the diffusion pyrotechnic. This is because the relatively high temperature of heat insulation and fast combustion speed of hydrogen facilitated the production of thermal NOx. On the other hand, CO2 production tended to decrease as hydrogen was added to reduce the overall carbon ratio contained in the mixed diffusion flame of methane, methane-propane, and methane-ethane-propane. This means that the mixed fuel use of LNG-hydrogen in ships may potentially reduce emissions of CO2, a greenhouse gas.

Comparison of Opened Rates and Quality Characteristics of Frozen Baby-clam In-shell Tapes philippinarum Prepared by Different Processing Method (제조방법을 달리하여 제조한 껍질붙은 냉동바지락(Tapes philippinarum)의 껍질 개패율 및 품질특성 비교)

  • Park, Si-Young;Kang, Kyung-Hun;Lee, Jae-Dong;Yoon, Moon-Joo;Kang, Young-Mi;Seoung, Tae-Jong;Kweon, Su-Hyun;Choo, Yi-Kwon;Kim, Jeong-Gyun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.49 no.6
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    • pp.743-749
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    • 2016
  • We compared two different processing methods for preparing high quality frozen in-shell baby clam products. In the first method, sand and mud were removed from the clams, then they were vacuum packed in polyethylene film, boiled at $97^{\circ}C$ for 6 min, and snap frozen in a cold air blast freezer (sample 1). The second processing method was similar, except the boiling process was excluded (sample 2). Both frozen products were boiled for 4 min, and then shucked and minced. Various quality metrics, such as the opening rates of shells, chemical composition, pH, volatile basic nitrogen (VBN), salinity, thiobarbituric acid (TBA), amino-N, total amino acids and free amino acids were measured, and sensory evaluation was conducted. The opening rates of shells of sample 1 and sample 2 were 98.3% and 4.67%, respectively. The proximate composition of sample 1 and sample 2 was 75.2% and 78.7% moisture, 19.7% and 16.2% crude protein, 2.45 and 2.2% crude lipid, 2.8% and 2.1% ash, and 2.1% and 1.9% salinity, respectively. The L, a, b and ${\Delta}E$ values were similar: 48.6 and 49.2, 3.9 and 3.9, 15.7 and 15.5, and 50.7 and 50.1 for sample 1 and sample 2, respectively. The sensory evaluation score of sample 1 was higher than that of sample 2. Sample 1 was deemed to be superior to sample 2; therefore, we determined that the boiling process is needed for manufacturing high-quality frozen clam products.

Engineering Performance and Applicability of Environmental Friendly Porous Concrete for a Marine Ranch Using Steel Industry By-products (철강산업 부산물을 활용한 해양목장 조성용 친환경 다공질 콘크리트의 공학적 성능 및 적용성)

  • Lee, Byung-Jae;Jang, Young-Il;Kim, Yun-Yong
    • Journal of the Korea Concrete Institute
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    • v.25 no.1
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    • pp.115-123
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    • 2013
  • The steel industry, a representative industry that significantly consumes raw materials and energy, produces steel as well as a large amount of by-product steel slag through the production process. The vast habitat foundation of marine life has been destroyed due to recent reckless marine development and environment pollution, resulting in intensification of the decline of marine resources, and a solution to this issue is imperative. In order to propose a method to recycle large amounts of by-product slag into a material that can serve as an alternative to natural aggregate, the engineering properties and applicability for each mixing factor of environment friendly porous concrete as a material for the composition of marine ranches were evaluated in this study. The test results for percentage of voids per mixing ratio revealed that the margin of error for all conditions was within 2.5%. The compressive strength test results showed that the most outstanding environmental friendly porous concrete can be manufactured when mixing 30% slag aggregate and 10% specially treated granular fertilizer for the optimum volume fraction. As concrete for marine applications, the best seawater resistance was obtained with mixing conditions for high compression strength. An assessment of the ability to provide a marine life habitat foundation of environmentally friendly porous concrete showed that a greater percentage of voids facilitated implantation and inhabitation of marine life, and the mixing of specially treated granular fertilizer led to active initial implantation and activation of inhabitation. The evaluation of harmfulness to marine life depending on the mixture of slag aggregate and specially treated granular fertilizer revealed that the stability of fish is secured.