• Title/Summary/Keyword: Area Detection

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Quantitative Analysis of Microplastics in Coastal Seawater of Taean Peninsula using Fluorescence Measurement Technique (형광측정기법을 이용한 태안반도 연안 표층수의 미세플라스틱 정량분포 스크리닝)

  • Un-Ki Hwang;Hoon Choi;Ju-Wook Lee;Yun-Ho Park;Wonsoo Kang;Moonjin Lee
    • Journal of Marine Life Science
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    • v.8 no.1
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    • pp.68-77
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    • 2023
  • In this study, we investigated the quantitative distribution of microplastics in the surface seawater at 8 points near the Taean Peninsula using fluorescence staining. The study revealed a detection range of microplastics from 0 to 360.5 particles/l, with an average of 149.7 ± 46.0 particles/l. When classifying the microplastics by size, it was found that particles smaller than 50 ㎛ were dominant, although there were differences at Site 3. Moreover, it was not possible to identify clear correlations when comparing the number of microplastics based on collection area and particle size. Various physical and chemical factors, including plastic material, dynamic ocean conditions (such as currents, wind, waves, tides), geological characteristics (topography, slope), sediment materials including coastal organisms, human activities (fishing, development, tourism), and weather conditions (floods, rainfall), affect the behavior of microplastics. Therefore, future efforts should focus on standardizing quantitative analysis methods and conducting fundamental research on microplastic monitoring, including the analysis of environmental factors.

Detection of Microcystin Synthetic Cyanobacteria and Variation of Intracellular Microcystin Synthesis Using by eDNA and eRNA in Freshwater Ecocystem (담수환경에서 eDNA와 eRNA를 이용한 Microcystin 합성 남조류 탐색 및 세포 내 Microcystin 생합성 활성 변화)

  • Keonhee Kim;Chaehong Park;Hyeonjin Cho;Daeryul Kwon;Soon-Jin Hwang
    • Korean Journal of Ecology and Environment
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    • v.56 no.1
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    • pp.1-13
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    • 2023
  • Targeting Microcystin (MC), which is most abundantly detected in the North-Han River water area, we analyzed the relationship between the MC biosynthesis gene (mcyA gene), cyanobacteria cell density, and MC concentration, derived an RNA-MC conversion formula, and derived the cyanobacteria. The concentration of MC present in cells was predicted. In the North-Han River waters, the mcyA gene was found mainly at downstream sites of the North-Han River after Muk-Hyeon Stream junction, and higher copy numbers were found on average than other sites. In the Uiam Lake waters upstream of the North-Han River, the mcyA gene copy number increased at the Kong-Ji Stream point, and after September, the mcyA gene copy number decreased throughout the North-Han River waters. The expression of the mcyA gene was concentrated in the short period of summer due to the spatio-temporal difference between upstream and downstream water bodies. The mcyA gene expression level was not only highly correlated with MC concentration, but also correlated with the cell density of Microcystis aeruginosa and Dolichospermum circinale, which are known to biosynthesize MC. Six conversion formulas derived based on the RNA-MC relationship showed statistical significance (p<0.05) and exhibited high correlation coefficients (r) of 0.9 or higher. The expression level of MC biosynthesis gene present in eRNA determines the synthesis of cyanotoxin substances in water, quickly quantifies gene activity, and can be fully utilized for early warning of MC development.

A Non-enzymatic Hydrogen Peroxide Sensor Based on CuO Nanoparticles/polyaniline on Flexible CNT Fiber Electrode (CuO Nanoparticles/polyaniline/CNT fiber 유연 전극 기반의 H2O2 검출용 비효소적 전기화학 센서)

  • Min-Jung Song
    • Korean Chemical Engineering Research
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    • v.61 no.2
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    • pp.196-201
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    • 2023
  • In this study, a CNT fiber flexible electrode grafted with CuO nanoparticles (CuO NPs) and polyaniline (PANI) was developed and applied to a nonenzymatic electrochemical sensor for H2O2 detection. CuO NPs/PANI/CNT fiber electrode was fabricated through the synthesis and deposition of PANI and CuO NPs on the CNT fiber surface using an electrochemical method. Surface morphology and elemental composition of the CuO NPs/PANI/CNT fiber electrode were characterized by scanning electron microscope with energy dispersive X-ray spectrometry. And its electrochemical characteristics were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). Compared with a bare CNT fiber as a control group, the CuO NPs/PANI/CNT fiber electrode showed a 4.78-fold increase in effective surface area and a 8.33-fold decrease in electron transfer resistance, which leads to excellent electrochemical properties such as a good electrical conductivity and an efficient electron transfer. These improved characteristics were due to the synergistic effect through the grafting of CNT fiber, PANI and CuO NPs. As a result, this electrode enhanced the H2O2 sensing performance.

Concentration of heavy metals in shellfishes and health risk assessment from Korean coastal areas

  • Ka Jeong Lee;Eun Hye Kang;Minchul Yoon;Mi Ra Jo;Hong Sik Yu;Kwang Tae Son
    • Fisheries and Aquatic Sciences
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    • v.25 no.12
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    • pp.626-636
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    • 2022
  • Shellfish are exoskeleton-bearing aquatic invertebrates that consume various organic and inorganic substances floating in seawater through filter feeding. Heavy metals are known as absorbed and accumulated in seawater. Some of the toxic heavy metals are highly accumulated in seawater, and exposure to them can cause a variety of risks to the human body. Since Koreans like to eat seafood, they are more likely to be exposed to contaminated seafood with heavy metals. In this study, nine types of heavy metals were analyzed on ten different shellfish species in the coastal area of South Korea. The risk assessment was also done on shellfish in which heavy metals were detected. Zinc (Zn) and copper (Cu) were identified at an average of 56.7 mg/kg (6.70 to 466 mg/kg) and 13.2 mg/kg (0.064 to 143 mg/kg), respectively. Lead (Pb) average of 0.208 mg/kg (0.000750 to 1.02 mg/kg), cadmium (Cd) average of 0.454 mg/kg (0.0388 to 1.56 mg/kg) and mercury (Hg) average of 0.0266 mg/kg (0.00548 to 0.174 mg/kg) were identified. Additionally, arsenic (As), chromium (Cr), nickel (Ni), and silver (Ag) were also identified as average concentrations of 4.02 (0.460 to 15.0 mg/kg), 0.167 (< limit of quantification [LOQ] to 0.820 mg/kg), 0.281 (< LOQ to 1.46 mg/kg), and 0.158 mg/kg (< LOQ to 1.15 mg/kg). The result indicates that the monitoring results of heavy metals in most shellfish satisfied the Korean standard. However, Pb and Cd have exceeded some foreign standards, such as the United States and the EU. The permissible human exposure calculated using the heavy metal intake and detection amount was lower than the Joint FAO/WHO Expert Committee on Food Additives human safety standard, and the risk of heavy metals from shellfish consumption was at an acceptable level.

It Was Possible to Reduce the Pain of the Victims of Humidifier Disinfectant (가습기살균제 피해자의 아픔을 줄일 수 있었다)

  • Kim, Pangyi;Choi, Yoon-Hyeong;Park, YeongChul;Park, Tae-Hyun;Leem, JongHan
    • Journal of Environmental Health Sciences
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    • v.48 no.1
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    • pp.1-8
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    • 2022
  • Objectives: The purpose of this study is to reveal the circumstances under which the cases of harm to health caused by humidifier disinfectant were neglected and show the points where the number of victims and the degree of damage could have been reduced. In addition, it attempts to describe how damage management proceeded immediately after the incident and actually exacerbated the damage. Finally, it explores the unfortunate aspects of the recent trial. By doing so, it attempts to take this as an opportunity to consider whether a tragic event such as the humidifier disinfectant incident could occur in the future. Methods: This study collected and analyzed data on chemical material characteristics related to humidifier disinfectants, data on health effect characteristics, data on related laws and regulations from the Ministry of Environment, data related to the damage investigation by the Korea Environmental Industry and Technology Institute, and current contents. Results: The lack of related systems and laws is the area where the greatest responsibility for the cause of the humidifier disinfectant disaster falls, so it is difficult for the government to escape this responsibility. Establishing a dedicated department to identify the prevalence of certain diseases within the functions of the Health Insurance Review and Assessment Service to monitor health can greatly contribute to the prevention and management of diseases through early detection and management of group outbreaks caused by harmful factors. Humidifier disinfectant damage relief should have been expanded earlier beyond HDLI (humidifier disinfectant lung injury) to include non-specific diseases such as asthma, pneumonia, and interstitial pneumonia. The scope of relief benefits should have also been expanded earlier to include the payment of disability benefits. Fortunately, with the 2020 revision of the Special Act, the conditions for estimating causal relations were eased and individual screening systems such as health impact assessment were reorganized along with the introduction of a rapid screening system. Conclusions: The management system for chemical substances in a country is clearly of paramount importance, and the ministry in charge must have a response system in case of damage to health effects. Administration that looks at the victims' situation from their point of view is needed, and technical countermeasures are required to quickly recognize the prevalence of certain diseases.

Tunnel Reverse Engineering Using Terrestrial LiDAR (지상LiDAR를 이용한 터널의 Reverse Engineering)

  • Cho, Hyung Sig;Sohn, Hong Gyoo;Kim, Jong Suk;Lee, Suk Kun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.6D
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    • pp.931-936
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    • 2008
  • Surveying by using terrestrial LiDAR(Light Detection And Ranging) is more rapid than by using total station which enables tunnel section profile surveying to be done in suitable time and minimize centerline error, occurrence of overcut and undercut. Therefore, utilization of terrestrial LiDAR has increased more and more in section profile survey and measurement field Moreover, studies of terrestrial LiDAR for accurate and efficient utilization is now ongoing vigorously. Average end area formula, which was generally used to calculate overcut and undercut, was compared with existing methods such as total station survey and photogrammetry. However, there are no criteria of spacing distance for calculating overcut and undercut through terrestrial LiDAR surveying which can acquire 3D information of whole tunnel. This research performed reverse engineering to decide optimal spacing distance when surveying tunnel section profile by comparing whole tunnel volume and tunnel volume in difference spacing distance. This result was utilized to produce CAD drawing for the test tunnel site where there is no design drawings. In addition to this, efficiency of LiDAR and accuracy of CAD drawing was compared with targetless total station surveying of tunnel section profile. Finally, error analysis of target coordinate's accuracy and incidence angle was done in order to verify the accuracy of terrestrial LiDAR technology.

Factors affecting the ability of older adults to identify symptoms of depression (노인의 우울증상 식별력에 영향을 미치는 요인)

  • Lee, Sun Hae;Ko, Jung Eun
    • 한국노년학
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    • v.29 no.2
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    • pp.529-546
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    • 2009
  • Depression in old age not only is prevalent but also causes a considerable amount of burden in physical, psychosocial, and economic terms. Intervention, however, is often delayed due to the understanding that considers depressive symptoms as a normal process of aging or signs of physical illnesses. Since the recognition of symptoms often initiate one's help seeking process, a correct identification of symptoms can contribute to early detection and intervention to depression in oneself as well as in others. This study interviewed 104 older adults living in an urban area, and explored their ability to correctly identify depressive symptoms and factors related to identification. The study results show that respondents who were able to correctly identify symptoms of depression were only 14%, and the rest defined the symptoms as social, economic, and other psychological issues. Of the factors in the logistic regression model, age being 75 and over and mass media as source of mental health information affected negatively their ability to correctly identify symptoms; mental health education programs affected positively their ability. Based on these results, it is suggested that such strategies as employing a face-to-face provision of concrete information and counseling can be more effective than delivering information via large-scale lectures. Additionally, a future research deems necessary to conduct an in-depth examination of mental health/illness-related contents on mass media.

Changes in the Riverbed Landforms Due to the Artificial Regulation of Water Level in the Yeongsan River (인위적인 보 수위조절로 인한 영산강 하도 지형 변화)

  • Lim, Young Shin;Kim, Jin Kwan
    • Journal of The Geomorphological Association of Korea
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    • v.27 no.1
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    • pp.1-19
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    • 2020
  • A river bed which is submerged in water at high flow and becomes part of the river at low flow, serves as a bridge between the river and the land. The channel bar creates a unique ecosystem with vegetation adapted to the particular environment and the water pool forms a wetland that plays a very important role in the environment. To evaluate anthropogenic impacts on the river bed in the Middle Yeongsangang River, the fluvial landforms in the stream channel were analyzed using multi-temporal remotely-sensed images. In the aerial photograph of 2005 taken before the construction of the large weirs, oxbow lakes, mid-channel bars, point bars, and natural wetlands between the artificial levees were identified. Multiple bars divided the flow of stream water to cause the braided pattern in a particular section. After the construction of the Seungchon weir, aerial photographs of 2013 and 2015 revealed that most of the fluvial landforms disappeared due to the dredging of its riverbed and water level control(maintenance at 7.5El.m). Sentinel-2 images were analyzed to identify differences between before and after the opening of weir gate. Change detection was performed with the near infrared and shortwave infrared spectral bands to effectively distinguish water surfaces from land. As a result, water surface area of the main stream of the Yeongsangang River decreased by 40% from 1.144km2 to 0.692km2. A large mid-channel bar that has been deposited upstream of the weir was exposed during low water levels, which shows the obvious influence of weir on the river bed. Newly formed unvegetated point bars that were deposited on the inside of a meander bend were identified from the remotely sensed images. As the maintenance period of the weir gate opening was extended, various habitats were created by creating pools and riffles around the channel bars. Considering the ecological and hydrological functions of the river bed, it is expected that the increase in bar areas through weir gate opening will reduce the artificial interference effect of the weir.

Development of Multi-channel Detector of X-ray Backscatter Imaging (후방산란 엑스선 영상획득을 위한 다채널 검출기 개발)

  • Lee, Jeonghee;Park, Jongwon;Choi, Yungchul;Lim, Chang Hwy;Lee, Sangheon;Park, Jaeheung
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2022.10a
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    • pp.245-247
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    • 2022
  • Backscattered x-ray imaging is a technology capable of acquiring an image inside an irradiated object by measuring X-rays scattered from an object. For image acquisition, the system must include an X-ray generator and a detection system for measuring scattered x-rays. The imaging device must acquire a real-time signal at sampling intervals for x-rays generated by passing through a high-speed rotating collimator, and for this purpose, a high-speed signal acquisition device is required. We developed a high-speed multi-channel signal acquisition device for converting and transmitting signals generated by the sensor unit composed of a large-area plastic scintillator and a photomultiplier tube. The developed detector is a system capable of acquiring signals at intervals of at least 15u seconds and converting and transmitting signals of up to 6 channels. And a system includes remote control functions such as high voltage, signal gain, and low level discrimination for individual calibration of each sensor. Currently, we are conducting an application test for image acquisition under various conditions.

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Development of a Method for Tracking Sandbar Formation by Weir-Gate Opening Using Multispectral Satellite Imagery in the Geumgang River, South Korea (금강에서 다분광 위성영상을 이용한 보 운영에 따른 모래톱 형성 추적 방법의 개발)

  • Cheolho Lee;Kang-Hyun Cho
    • Ecology and Resilient Infrastructure
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    • v.10 no.4
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    • pp.135-142
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    • 2023
  • A various technology of remote sensing and image analysis are applied to study landscape changes and their influencing factors in stream corridors. We developed a method to detect landscape changes over time by calculating the optical index using multispectral images taken from satellites at various time points, calculating the threshold to delineate the boundaries of water bodies, and creating binarized maps into land and water areas. This method was applied to the upstream reach of the weirs in the Geumgang River to track changes in the sandbar formed by the opening of the weir gate. First, we collected multispectral images with a resolution of 10 m × 10 m taken from the Sentinel-2 satellite at various times before and after the opening of the dam in the Geumgang River. The normalized difference water index (NDWI) was calculated using the green light and near-infrared bands from the collected images. The Otsu's threshold of NDWI calculated to delineate the boundary of the water body ranged from -0.0573 to 0.1367. The boundary of the water area determined by remote sensing matched the boundary in the actual image. A map binarized into water and land areas was created using NDWI and the Otsu's threshold. According to these results of the developed method, it was estimated that a total of 379.7 ha of new sandbar was formed by opening the three weir floodgates from 2017 to 2021 in the longitudinal range from Baekje Weir to Daecheong Dam on the Geumgang River. The landscape detection method developed in this study is evaluated as a useful method that can obtain objective results with few resources over a wide spatial and temporal range.