• Title, Summary, Keyword: marine zone

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Study on the Corrosive Characters of Carbon Steel in the Marine Splash Zone

  • Zhu, Xiangrong;Han, Bing
    • Corrosion Science and Technology
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    • v.2 no.1
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    • pp.26-29
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    • 2003
  • This study determined that the four corrosive characters of carbon steel in the marine splash zone (MSZ) in China's four sea areas. It has a range and a corrosion peak value. The rust in the MSZ plays the role of "depolarizer" in the cathodic process of corrosion. The growth law of the rust layer in MSZ has a character of "annual ring". In addition the reasons causing serious corrosion of carbon steel in the marine splash zone has been discussed in this paper.

Prediction of Effect Zone for Marine Organisms Using Distance Attenuation Equations for Oceanic Noise (수중소음 거리감쇠 특성식을 이용한 해양생물 피해영향범위 예측)

  • Ha, Jeong-Min;Lee, Jong-Myeong;Lee, Jeong-Hoon;Gu, Dong-Sik;Choi, Byeong-Keun
    • Journal of Ocean Engineering and Technology
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    • v.26 no.2
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    • pp.14-19
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    • 2012
  • There are insufficient data to consider the effect zone for the marine life of coastal fisheries, because no standard has been defined for the sound level of marine life. In this study, equations for distance attenuation were used to determine the effect zone for oceanic noises. A reference noise level was divided into 4 parts to consider the characteristics of the fishes, and the effect zone of each reference noise level was determined. To increase the reliability of the effect scope, approximately 100 repetitions of blasting work split into several parts by the boring depth, the sound level of the source caused by an increase in weight, and the effect zone were calculated using the prediction equation. According to the prediction, the maximum distance of the effect zone was 4.92 km.

Evaluation of Durability of Slag Concrete by Marine Environment Exposure (해양환경 폭로에 의한 슬래그 콘크리트의 내구성 평가)

  • Kim, Hyun-Jin;Kim, Gyu-Yong;Choe, Gyeong-Cheol;Kim, Hong-Seop;Lee, Bo-Kyeong;Kim, Rae-Hwan
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.111-112
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    • 2015
  • There is high possibility of steel corrosion on the reinforced concrete exposed to marine environment by chloride ion penetration. And it show a big difference of concrete durability under conditions of splash zone, tidal zone, and immersion zone. Therefore, in this paper, half-cell potential and chloride ion penetration depth was measured to evaluate the durability of slag concrete by marine exposure experiment. As a result, SC70 specimen showed no steel corrosion, regardless of the marine exposed conditions. Also, a deterrent effect on chloride ion penetration by replacement of slag in tidal zone and immersion zone could be confirmed.

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A Study on the Economic Impact of the Marine Leisure Sector Following the Designation of Haeundae as 'Convention, Movie, Marine Leisure Special Zone

  • Hwang, Young-Woo;Ryu, Tae-Chang;Yhang, Wii-Joo
    • Journal of Navigation and Port Research
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    • v.30 no.4
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    • pp.303-308
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    • 2006
  • This study is designed to analyze the production, employment, value added and income impacts tha, in the event of designation and development of Haeundae as 'Convention, Movie, Marine Leisure Special Zone', its marine sector would have on the local economy. The realization of marine leisure special zone of Haeundae in Busan is expected to lead to a direct and indirect investment of approx. \13.6 billion, resulting in \68.0 billion in production impact, 850 jobs in employment impact, \28.0 billion in value added impact and \14.5 billion in income impact. This is expected to give a boost to a stagnant local economy, offering opportunities for the revival of Busan's tourist industry.

An Electrochemical Evaluation on the Corrosion of Weld Zone in Cold Arc Welding of the Cast Iron

  • Moon, Kyung Man;Kim, Jin Gyeong;Lee, Myung Hoon;Kim, Ki Joon
    • Corrosion Science and Technology
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    • v.7 no.2
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    • pp.134-137
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    • 2008
  • Cold arc welding of cast iron has been widely used with repair welding of metal structures. However its welding is often resulted in the galvanic corrosion between weld metal zone and heat affected zone(HAZ) due to increasing of hardness. In this study, corrosion properties such as hardness, corrosion potential, surface microstructures, and variation of corrosion current density of welding zone with parameters of used electrodes for cast iron welding were investigated with an electrochemical evaluation. Hardness of HAZ showed the highest value compared to other welding zone regardless of kinds of used electrodes for cast iron welding. And its corrosion potential was also shifted to more negative direction than other welding zone. In addition, corrosion current density of WM in polarization curves was qualitatively smaller than that of HAZ. Therefore galvanic corrosion may be apparently observed at HAZ. However galvanic corrosion may be somewhat controlled by using an optimum welding electrode.

Seasonal Dynamics of Marine Benthic Communities in Intertidal Zone of Gwangyang Bay, Southern Coast of Korea

  • Yoo, Jong-Su
    • Ocean and Polar Research
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    • v.25 no.4
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    • pp.519-528
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    • 2003
  • Species composition and community structure of marine benthic community were studied in the intertidal zone of Jijindo Island, Gwangyang Bay. A total of 85 species of benthic marine plants including the 5 Cyanophyta, 9 Chlorophyta, 13 Phaeophyta, 56 Rhodophyta and 2 Magnoliophyta that were listed. The community structure was represented by Gelidium divaricatum in the upper zone, Celidium divalicatum and Ulva pertusa in the middle, and Ulva pertusa, Chondria crassicaulis, Chondracanthus intermedia and Sargassum thunbergii in the lower intertidal zone. The dominant species in the rnscro-zoobenthic community were Chthamalux challengeri in the upper and middle, Littorina brevicula between the upper and middle, and Mytilus edulis and Crassostrea gigas in the middle and lower intertidal zones. The economic benthic organisms such as Undaria pinnatifida, Mytilus edulis, and Crassostrea gigas found in the lower intertidal zone were frequently disturbed due to their collection by local resident. Therefore, it is necessary to record the correct information pertaining to these cases. The species diversity indices estimated kom different sources were quite different. They were 2.22 derived from frequency, 1.67 based on coverage, 2.17 based on sum of frequency and coverage and 2.04 derived from importance value. Species diversity and number of algal species in Gwangyang Bay have noticeably decreased, compared with their previously reported status. It is estimated that their decreases were caused by changes in the marine environment, especially pertaining to the polychaete community resulting from reclamation and dredging activity undertaken for the industrial development.

Structural Characteristics of Benthic Algal Community in the Subtidal Zone of Yeongil Inner and Outer Bay (영일만 내,외해역에서 조하대 해조군집 구조의 특성)

  • Yu,Jong-Su
    • ALGAE
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    • v.18 no.4
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    • pp.365-369
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    • 2003
  • Algal flora and community structure of benthic marine algae in the subtidal zone, Yeongil Bay area were studied. The number of algal species in the quadrats were identified totally 78: 2 Cyanophyta, 10 Chlorophyta, 19 Phaeophyta, and 47 Rhodophyta. The dominant species based on biomass were Sargassum hornerii, Undaria pinnatifida, and Sargassum thunbergii. Vertical distribution was clear by the representative algae such as, Undaria pinnatifida, Sargassum thunbergii, Sargassum horneri, Corallina spp. in the upper subtidal zone, Undaria pinnatifida, Sargassum horneri, Caulerpa okamurae in the middle zone, and Dictyopteris divaricata in the lower zone.

Community Dynamics of Benthic Marine Algae in the Intertidal and Subtidal Rocky Shore of Samyang, Jejudo Island

  • Yoo,Jong-Su
    • ALGAE
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    • v.18 no.4
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    • pp.301-309
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    • 2003
  • Community structure and vertical distribution of benthic marine algae were investigated in the intertidal and subtidal rocky shore of Samyang, Jejudo Island. The total number of 62 algal species composed of 6 Cyanophyta, 6 Chlorophyta, 19 Phaeophyta, and 31 Rhodophyta were observed. The dominant species were melobesioidean algae, Sargassum thunbergii, Hizikia fusiformis, and Ulva pertusa in the intertidal zone and melobesioidean algae, Ulva pertusa, Corallina spp., and Undaria pinnatifida in the subtidal zone. The vertical algal distribution was represented by the melobesioidean algae in the whole rocky shore, Caulacanthus ustulatus in the upper intertidal zone, Sargassum thunbergii and Hizikia fusiformis in the middle and lower zone, Ulva pertusa in the lower zone and Ulva pertusa, Corallina spp., and Undaria prinnatifida in the subtidal zone. The composition of dominant species and pattern of the vertical distribution of algae in the present study were significantly different from the previous reports. Especially, distribution of crustose coralline algae was significantly extended.

Temporal Variation of Seaweed Biomass in Korean Coasts: Yokjido, Gyeongnam Province (한국 연안 해조류 생물량의 연간 변동 양상: 경상남도 욕지도 지역)

  • Choi, Chang-Geun;Kim, Jeong-Ha;Chung, Ik-Kyo
    • ALGAE
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    • v.23 no.4
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    • pp.311-316
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    • 2008
  • The seasonal variation of marine algal biomass and community were studied with nondestructive sampling and quadrat method during May 2006 to April 2008 in the intertidal and subtidal zone at Yokjido. As result, total 120 species, 13 Chlorophyta, 34 Phaeophyta, 71 Rhodophyta and 2 Spermatophyta were identified in this study. The major species which contributed significantly to the total biomass were Ulva pertusa, Undaria pinnatifida, Ecklonia stolonifera, Sargassum horneri, S. serratifolium, Gelidium amansii and Prionitis cornea. The mean biomass was 235.5 g wet wt m$^{-2}$ in intertidal, 1,038.9 g wet wt m$^{-2}$ in 1 m, 1,013.1 g wet wt m$^{-2}$ in 5 m, and 19.7 g wet wt m$^{-2}$ in 10 m depths of mean sea level. Seasonal biomass change in intertidal zone, the peak season was in spring, while the lowest was in autumn. The vertical distribution of marine vegetation was characterized by Ulva pertusa - Gelidium divaricatum - Gloiopeltis furcata - Sargassum thunbergii - Hizikia fusiformis at intertidal zone, and Caulerpa okamurae - Gelidium amansii - Chondrus ocellatus - Ecklonia stolonifera - Sargassum horneri - Gracilaria textorii at subtidal zone. These result indicates that the marine algal species and biomass of 1 m and 5 m depths in subtidal zone are greater than intertidal zone, and Ecklonia stolonifera and Sargassum spp. are the dominant species of Yokjido.

A Spring Marine Algal Vegetation in the Muan, Jindo and Geomundo Coast, Western South Sea of Korea (한국 서남해역 무안, 진도와 거문도의 춘계 해조식생)

  • LIM, Su Yeon;KANG, Man-Gu;LEE, Chang Hyeok;KIM, Seong Ju;SHIN, Jong-Ahm
    • Journal of Fisheries and Marine Sciences Education
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    • v.29 no.2
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    • pp.612-625
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    • 2017
  • To grasp the algal vegetation using the occurred species number, biomass and dominant species, this study was performed in the subtidal zone of Muan-gun, in the intertidal zone of Jindo-gun and in the intertidal zone and subtidal zone of Geomundo, the south-eastern coast of Jeollanamdo, Korea in the spring 2014. The total occurred species was 140 ones including 10 chlorophytes(7.14%), 54 phaeophytes(38.57%) and 76 rhodophytes(54.29%); the biomass was $70,484g{\cdot}w{\cdot}w/m^2$ in total. The flora charateristic using R/P ratio, geographical distribution pattern of algae, at the Station 9-1(intertidal zone) in Geomundo was tropical; the flora at the Station 6 (Maengseong-ri, Sanjodo, Jindo-gun) and the Station 9-2(subtidal zone) in Geomundo were mixed; the others were arctic to temperate. The physiognomic types were also shown. Each species was classified into six functional-form groups, and two ecological state groups(ESG) were evaluated based on these groups. The coarsely branched-group of functional-form groups was 44% of total occurred species. The ESG II in all study sites was high, and this is maybe due to the environmental stress such as pollution and disturbance, etc.