• Title/Summary/Keyword: LONG-TERM MONITORING

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Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.64.2-64.2
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    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

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SOMANGNET: SMALL TELESCOPE NETWORK OF KOREA

  • Im, Myungshin;Kim, Yonggi;Lee, Chung-Uk;Lee, Hee-Won;Pak, Soojong;Shim, Hyunjin;Sung, Hyun-Il;Kang, Wonseok;Kim, Taewoo;Heo, Jeong-Eun;Hinse, Tobias C.;Ishiguro, Masateru;Lim, Gu;Ly, Cuc T.K.;Paek, Gregory S.H.;Seo, Jinguk;Yoon, Joh-na;Woo, Jong-Hak;Ahn, Hojae;Cho, Hojin;Choi, Changsu;Han, Jimin;Hwang, Sungyong;Ji, Tae-Geun;Lee, Seong-Kook J.;Lee, Sumin;Lee, Sunwoo;Kim, Changgon;Kim, Dohoon;Kim, Joonho;Kim, Sophia;Jeong, Mankeun;Park, Bomi;Paek, Insu;Kim, Dohyeong;Park, Changbom
    • Journal of The Korean Astronomical Society
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    • v.54 no.3
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    • pp.89-102
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    • 2021
  • Even in an era where 8-meter class telescopes are common, small telescopes are considered very valuable research facilities since they are available for rapid follow-up or long term monitoring observations. To maximize the usefulness of small telescopes in Korea, we established the SomangNet, a network of 0.4-1.0 m class optical telescopes operated by Korean institutions, in 2020. Here, we give an overview of the project, describing the current participating telescopes, its scientific scope and operation mode, and the prospects for future activities. SomangNet currently includes 10 telescopes that are located in Australia, USA, and Chile as well as in Korea. The operation of many of these telescopes currently relies on operators, and we plan to upgrade them for remote or robotic operation. The latest SomangNet science projects include monitoring and follow-up observational studies of galaxies, supernovae, active galactic nuclei, symbiotic stars, solar system objects, neutrino/gravitational-wave sources, and exoplanets.

Characteristics of Groundwater Levels Fluctuation and Quality in Ddan-sum Area (낙동강 하중도 딴섬의 지하수위 변동 및 수질 특성)

  • Kim, Gyoobum;Choi, Doohoung;Shin, Seonho
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.2
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    • pp.35-43
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    • 2011
  • Confined aquifer, which is separated with upper clayey or silty materials, is partially distributed at the depths of the sediments in Ddan-sum area on the lower Nakdong river. Measurements of groundwater levels at 13 sites explain that groundwater flow shows seasonally various due to seasonal rainfall and agricultural water use. From 9 long-term monitoring data of groundwater levels at 7 sites, 3 types of groundwater levels time series can be classified using principal component analysis. The first type is seen in the center of Ddan-sum and has a round-shape graph due to a weak response to stream water levels. The second type exists in the outer part of Ddan-sum and shows sharply peak-shape graph due to a rapid and strong response to stream water levels and rainfall. The last type, which is seen in a deep layer, has a periodicity by tital effect. From geochemical analysis at each monitoring sites, [$Ca-HCO_3$] type happens in the center of Ddan-sum far from Nakdong river, and [$Na-HCO_3$] and [$Ca-SO_4(Cl)$] types exist in the outer of Ddan-sum affected by river quality.

Monitoring Culicine Mosquitoes (Diptera: Culicidae) as a Vector of Flavivirus in Incheon Metropolitan City and Hwaseong-Si, Gyeonggi-Do, Korea, during 2019

  • Bahk, Young Yil;Park, Seo Hye;Kim-Jeon, Myung-Deok;Oh, Sung-Suck;Jung, Haneul;Jun, Hojong;Kim, Kyung-Ae;Park, Jong Myong;Ahn, Seong Kyu;Lee, Jinyoung;Choi, Eun-Jeong;Moon, Bag-Sou;Gong, Young Woo;Kwon, Mun Ju;Kim, Tong-Soo
    • Parasites, Hosts and Diseases
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    • v.58 no.5
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    • pp.551-558
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    • 2020
  • The flaviviruses are small single-stranded RNA viruses that are typically transmitted by mosquitoes or tick vectors and are etiological agents of acute zoonotic infections. The viruses are found around the world and account for significant cases of human diseases. We investigated population of culicine mosquitoes in central region of Korean Peninsula, Incheon Metropolitan City and Hwaseong-si. Aedes vexans nipponii was the most frequently collected mosquitoes (56.5%), followed by Ochlerotatus dorsalis (23.6%), Anopheles spp. (10.9%), and Culex pipiens complex (5.9%). In rural regions of Hwaseong, Aedes vexans nipponii was the highest population (62.9%), followed by Ochlerotatus dorsalis (23.9%) and Anopheles spp. (12.0%). In another rural region of Incheon (habitat of migratory birds), Culex pipiens complex was the highest population (31.4%), followed by Ochlerotatus dorsalis (30.5%), and Aedes vexans vexans (27.5%). Culex pipiens complex was the predominant species in the urban region (84.7%). Culicine mosquitoes were identified at the species level, pooled up to 30 mosquitoes each, and tested for flaviviral RNA using the SYBR Green-based RT-PCR and confirmed by cDNA sequencing. Three of the assayed 2,683 pools (989 pools without Anopheles spp.) were positive for Culex flaviviruses, an insect-specific virus, from Culex pipiens pallens collected at the habitats for migratory birds in Incheon. The maximum likelihood estimation (the estimated number) for Culex pipiens pallens positive for Culex flavivirus was 25. Although viruses responsible for mosquito-borne diseases were not identified, we encourage intensified monitoring and long-term surveillance of both vector and viruses in the interest of global public health.

The Analysis of Coastal Erosion and Erosion Impact Assessment in the East Coast (동해안 침식 원인분석 및 침식 영향도 평가)

  • Park, Seon Jung;Seo, Heui Jung;Park, Seung Min;Park, Seol Hwa;Ahn, Ike Jang;Seo, Gyeong Sik
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.33 no.6
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    • pp.246-256
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    • 2021
  • Various development projects occurring on the coast cause an imbalance of surface sediments, causing coastal disasters or irreversible coastal erosion. Coastal erosion caused by the influence of various port structures built through coastal development can be directly identified by evaluating changes in the sediment budget, longshore sediment, and cross-shore sediment. In other words, it will be possible to evaluate the causality between coastal development and coastal erosion by classifying regions due to single cause and regions due to multiple causes according to the changes in the sediment classified into the three types mentioned above. In this study, the cause of long-term and continuous erosion was analyzed based on the analysis results of the coastal development history and the Coastal Erosion Monitoring targeting the coast of Gangwon-do and Gyeongsangbuk-do on the east coast. In addition, in order to evaluate the degree of erosion caused by the construction of artificial coastal structures, the concept of erosion impact assessment was established, three methods were proposed for the impact assessment. The erosion impact of Hajeo port was assessed using the results of satellite image analysis presented in the Coastal Erosion Monitoring Report, it was assessed that the development of Hajeo port had an impact of 93.4% on erosion, and that of the coastal road construction had an impact of 6.6%.

Development of web-based system for ground excavation impact prediction and risk assessment (웹기반 굴착 영향도 예측 및 위험도 평가 시스템 개발)

  • Park, Jae Hoon;Lee, Ho;Kim, Chang Yong;Park, Chi Myeon;Kim, Ji Eun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.23 no.6
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    • pp.559-575
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    • 2021
  • Due to the increase in ground excavation work, the possibility of ground subsidence accidents is increasing. And it is very difficult to prevent these risk fundamentally through institutional reinforcement such as the special law for underground safety management. As for the various cases of urban ground excavation practice, the ground subsidence behavior characteristics which is predicted using various information before excavation showed a considerable difference that could not be ignored compared to the results real construction data. Changes in site conditions such as seasonal differences in design and construction period, changes in construction methods depending on the site conditions and long-term construction suspension due to various reasons could be considered as the main causes. As the countermeasures, the safety management system through various construction information is introduced, but there is still no suitable system which can predict the effect of excavation and risk assessment. In this study, a web-based system was developed in order to predict the degree of impact on the ground subsidence and surrounding structures in advance before ground excavation and evaluate the risk in the design and construction of urban ground excavation projects. A system was built using time series analysis technique that can predict the current and future behavior characteristics such as ground water level and settlement based on past field construction records with field monitoring data. It was presented as a geotechnical data visualization (GDV) technology for risk reduction and disaster management based on web-based system, Using this newly developed web-based assessment system, it is possible to predict ground excavation impact prediction and risk assessment.

Effects of Urban Park on Thermal Comfort in Summer - An Analysis of Microclimate Data of Seoul Forest Park - (여름철 도시공원의 열환경 개선 효과 - 서울숲 미기상 관측자료 분석을 중심으로 -)

  • Zoh, Hyunmin Daniel;Kwon, Tae Kyung
    • Journal of the Korean Institute of Landscape Architecture
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    • v.50 no.6
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    • pp.30-41
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    • 2022
  • This study investigates the heat mitigation effects and thermal comfort improvement due to urban parks during summer. Self-developed monitoring devices to measure long-term microclimate data were installed in three spots, including the park plaza, waterside, and roadside in Seoul Forest Park, and measurements were taken from July 9 to July 30. The results of the measurement are as follows. The daily temperature of the park plaza and waterside were found to be 2.7℃ and 2.9℃ lower than the roadside and 5.5℃ and 7.4℃ lower than the roadside from 10:00 to 16:00. In addition, the Universal Thermal Climate Index (UTCI) measurement was applied to measure the thermal comfort at each point. In the average daily analysis, a significant difference was found between the park plaza, the waterside, and the roadside, and a greater difference was found between 10:00 to 16:00. Also, although there was no significant difference due to the weather condition, a statistically significant difference was also found in the average PM10 and CO2 concentrations. It is found to be higher in the order from the roadside, park plaza, and waterside for PM10 concentration and park plaza, roadside, and waterside for CO2. In sum, although the difference in measured microclimate data and thermal comfort index results were different depending on the time and weather conditions at the three points, the park plaza and waterside, which are located inside the park, showed improved thermal comfort conditions and lower temperatures than the roadside outside the park.

Ecological Monitoring on Changes in Microclimate, Vegetation and Soil Properties after 2 Years in Restoration Project Sites Linking the Ridgeline of Baekdudaegan (백두대간 생태축 복원사업 2년 후 산림미기상, 식생 및 토양특성 변화 모니터링)

  • Park, Yeong Dae;Kwon, Tae Ho;Ma, Ho Seop
    • Journal of agriculture & life science
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    • v.50 no.1
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    • pp.125-136
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    • 2016
  • The Korea Forest Service(KFS) has been initiating restoration activities of ridgeline in damaged and fragmented areas of Baekdudaegan since 2011. Completed project in Ihwaryeong, Yuksimnyeong & Beoljae(2012; 2013) were selected as sites for this study. The changes in microclimate condition, vegetation composition and soil properties between project sites and adjacent stands were compared to evaluate the effect of restoration at early stage(after 2years). Pinus densiflora was planted mainly for these restoration sites, however Robinia pseudoacacia and Alnus sibirica invaded the area two years after the restoration activities. Ihwaryeong showed the most changes in understory vegetation among the study sites. Exotic species, such as Ambrosia artemisiifolia, Oenothera odorata, Erigeron annuus, and Coreopsis tinctoria invaded Ihwaryeong, and the dominance have invaded currently. It resulted from the poor survival rate of trees and high difference in microclimate wherein there's an increased temperature and decreased humidity in both restored sites and adjacent stands. In addition, it is also caused by poor soil chemical property, especially pH and organic matter content due to lack of humus layer and its accumulation, compared to adjacent forest soil in restored sites. Significant difference on chemical soil property was observed between restored sites and adjacent forest but no significant difference was observed after two years of restoration. Ecological monitoring is needed to understand the ecological changes after restoration and to establish a long-term management strategy.

Construction Technology Research and Development Planning - In the Case of Real-time Construction Project Monitoring System Development - (건설 기술 연구 개발을 위한 기술 기획 - 적시 시공을 위한 시공 현장 모니터링 기술 사례를 기반으로 -)

  • Kim, Changyoon;Kim, Hyoungkwan;Kim, Changwan;Kim, Moon Kyum
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.6D
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    • pp.849-857
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    • 2008
  • Technology roadmapping is one of the widely used technology planning methodologies. Using a technology roadmap, the researchers can increase the possibility of the project success by systematic management of research contents, budgets, and commercialization strategies. Currently, Ministry of Land, Transport and Maritime Affairs has a plan to increase the research fund to improve the construction industry. As a result, the number of long term research projects with more than five years of research period, is increasing. This entails the need for a methodology for the systematic planning and management of research. However, the construction industry has the characteristics that the research results should ultimately be implemented in an outdoor environment. Through processes of diverse literature reviews, questionnaire-based survey, and pilot research, this paper presents a systematic procedure for the development of construction technology roadmaps, which can consider the unique nature of the construction industry. Based on the procedure, a technology roadmap for intelligent construction monitoring is also developed.

Analysis of Non-Biodegradable Organic Matter Leakage Characteristics and Correlation Analysis in Paldang Lake and its Upper Reaches (팔당호와 팔당호 상류의 난분해성 유기물질 유출 특성 분석 및 상관성 분석)

  • Chaewon Kang;Kyungik Gil
    • Journal of Wetlands Research
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    • v.25 no.4
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    • pp.221-229
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    • 2023
  • Extracted from the metropolitan area, the Paldang Lake, which supplies approximately 8 million tons of water, has achieved a BOD (Biochemical Oxygen Demand) of 1.1 mg/L as a result of water quality preservation policies. However, concerning the COD (Chemical Oxygen Demand) component that encompasses refractory organic matter, there has been an observable upward trend in concentration. The introduction of refractory organic matter into the water source of Paldang Lake brings potential increments in BOD, generates off-putting tastes and odors in tap water, increases THM (Trihalomethane) formation, and triggers algae proliferation. Moreover, if residual hazardous refractory pollutants persist in aquatic environments, they may induce endocrine disruption and phenomena such as antibiotic resistance. In this study, a monitoring campaign was executed to discern the concentration of refractory organic matter emissions from point and non-point sources within Paldang Lake and its upstream region, with the aim of managing refractory organic matter in Paldang Lake. By comparing refractory organic matter emission concentrations across monitored areas, the elimination efficiency at wastewater treatment plants was assessed. Additionally, employing the Pearson correlation correlation analysis technique, correlations among refractory organic matter indices, antecedent wet days, and antecedent dry days were explored. The concentrations of refractory organic matter in rivers and Paldang Lake exhibited a similar pattern. Wastewater treatment plant effluents exhibited higher concentrations compared to rivers and Paldang Lake. The assessment of refractory organic matter removal at wastewater treatment plants indicated a removal efficiency of 65.73%. However, no significant correlation emerged between refractory organic matter emission concentration and antecedent wet days or priory antecedent dry days. This absence of correlation is attributed to data scarcity, underscoring the need for long-term monitoring and data accumulation.