• Title/Summary/Keyword: Sunken HNS

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Experiment and Analysis of Backscattering Signals According to Presence or Absence of Chloroform (클로로폼 침적 유무에 따른 후방산란신호 측정 실험 및 분석)

  • Him Chan Seo;Jee Woong Choi;Yongmyung Kim;Moonjin Lee
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.spc
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    • pp.18-22
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    • 2022
  • Because it is difficult to apply direct and optical detection techniques to sunken hazardous and noxious substances (HNS), effective acoustic detection techniques are required to detect sunken HNS in water. In this study, the possibility of acoustic detection of sunken HNS was investigated through backscattering signal measurement experiments using chloroform, a sunken HNS. After establishing a pool in an acrylic tank, backscattering signals were measured according to the presences or absence of chloroform by varying the grazing angle from 90° to 50° in 0.5° intervals using a pan&tilt system. A directional transducer transmitted and received sinusoidal signals with a frequency of 200 kHz and a pulse length of 25 ㎲ in a monostatic state. When chloroform was deposited, the received level of the backscattering signal at the interface between water and chloroform became low at a grazing angle of approximately 80° or smaller. Based on the backscattering signal results obtained at the interface between water and chloroform, the possibility of acoustic detection of sunken HNS was demonstrated.

Experiment and Simulation of Acoustic Detection for the Substitute for Sunken Hazardous and Noxious Substances Using the High Frequency Active Sonar (고주파 능동소나를 이용한 저층 침적 위험유해물질 대체물질 음향 탐지 실험 및 모의)

  • Han, Dong-Gyun;Seo, Him Chan;Choi, Jee Woong;Lee, Moonjin
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.4
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    • pp.459-466
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    • 2018
  • Hazardous and Noxious Substances (HNS) are defined as substances that are likely to create a significant impact on human health and marine ecosystem when they are released into the marine environment. Recently, as the volume of HNS transported by ships increases, the rate of leakage accidents also increases. Therefore, research should be conducted to control and monitor sunken materials from the viewpoint of technology development for hazardous material leakage accident response. In this paper, acoustic detection experiments were carried out using HNS substitute materials in order to confirm the possibility of acoustic detection of sunken HNS on the sediment. The castor oil, which has a similar acoustic impedance with chloroform, is used as a substitute. 200 kHz high frequency signals were used to discriminate the reflected signals and measure reflection loss from the interface between water and castor oil. The reflection loss measured is in good agreement with the modeling results, showing a possibility of acoustic detection for sunken HNS.

Feasibility of Activated-Carbon Adsorbent to Sequester Sunken Hazardous and Noxious Substances (HNS) (흡착제를 이용한 침강 HNS 처리 및 현장적용 가능성 연구 - 현장 처리를 위한 활성탄소 활용 조건 검토 및 제안 -)

  • Choi, Ki-young;Kim, Chang-joon;Kim, Hye-eun;Jung, Jun-mo;Hwang, Ho-jin;Lee, Moonjin
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.7
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    • pp.858-863
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    • 2020
  • We experimented with the particle-settling velocity and CHCl3 absorption efficiency of seven activated-carbon and analyzed seven heavy metal contents by elution for application to the field treatment of sunken HNS on the marine seabed. The mean particle-settling velocity was in the range 0.5-8 cm/s, except when the 8-20 mesh was used. The larger the HNS particle, the faster the particle-settling velocity was, and the CHCl3 absorption efficiency increased considerably owing to the larger surface area. In addition, the elution test results showed that the total Zn and As contents in >100-meshed activated carbon was higher than the contents criteria for the standard for water-treatment agents, and Cr, Zn, and As were released at higher concentrations than those released by other activated-carbon groups. Taken together, the CHCl3 absorption efficiency, settling velocity, and elution test results suggested that the 20-60, 20-40, and 2mm&down mesh activated-carbon adsorbents could be applied to the field treatment of HNSs and that the minimum required amount for field treatment were 0.82, 0.90, and 1.28 ton/㎘, respectively, as calculated based on the HNS-adsorption-capacity priority.

Review on the Post-spill Monitoring Method of Sunken HNS and General Considerations (침강 HNS 유출사고 및 사고 후 모니터링 방법 및 고려사항)

  • Ki Young Choi;Chang Joon Kim;Young Il Kim;Yongmyung Kim;Moonjin Lee
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.spc
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    • pp.37-43
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    • 2022
  • Post-spill monitoring of hazardous noxious substances accidents is essential in the event of a spillage of significant quantities of pollutants and for the management of the marine environment resulting from the long-term effects of the persistent toxic substances. The accidental introduction of a sinker into the marine environment can create harmful anaerobic conditions in the benthic ecosystem and spread over the seafloor by the topography and currents. Through case studies, most post-spill monitoring includes modeling, remote sensing, and chemical analyses of the sediment and benthic organisms. The monitoring also evaluates the effectiveness of restoration and recovery activities and assesses damages and compensation.