KOMPSAT-3/3A 영상 기반 하천의 탁도 산출 연구

김다희,원유준,한상명,한향선,Kim, Dahui,Won, You Jun,Han, Sangmyung,Han, Hyangsun 대한원격탐사학회 2022 대한원격탐사학회지 Vol.38 No.6

Turbidity, the measure of the cloudiness of water, is used as an important index for water quality management. The turbidity can vary greatly in small river systems, which affects water quality in national rivers. Therefore, the generation of high-resolution spatial information on turbidity is very important. In this study, a turbidity retrieval model using the Korea Multi-Purpose Satellite-3 and -3A (KOMPSAT-3/3A) images was developed for high-resolution turbidity mapping of Han River system based on eXtreme Gradient Boosting (XGBoost) algorithm. To this end, the top of atmosphere (TOA) spectral reflectance was calculated from a total of 24 KOMPSAT-3/3A images and 150 Landsat-8 images. The Landsat-8 TOA spectral reflectance was cross-calibrated to the KOMPSAT-3/3A bands. The turbidity measured by the National Water Quality Monitoring Network was used as a reference dataset, and as input variables, the TOA spectral reflectance at the locations of in situ turbidity measurement, the spectral indices (the normalized difference vegetation index, normalized difference water index, and normalized difference turbidity index), and the Moderate Resolution Imaging Spectroradiometer (MODIS)-derived atmospheric products(the atmospheric optical thickness, water vapor, and ozone) were used. Furthermore, by analyzing the KOMPSAT-3/3A TOA spectral reflectance of different turbidities, a new spectral index, new normalized difference turbidity index (nNDTI), was proposed, and it was added as an input variable to the turbidity retrieval model. The XGBoost model showed excellent performance for the retrieval of turbidity with a root mean square error (RMSE) of 2.70 NTU and a normalized RMSE (NRMSE) of 14.70% compared to in situ turbidity, in which the nNDTI proposed in this study was used as the most important variable. The developed turbidity retrieval model was applied to the KOMPSAT-3/3A images to map high-resolution river turbidity, and it was possible to analyze the spatiotemporal variations of turbidity. Through this study, we could confirm that the KOMPSAT-3/3A images are very useful for retrieving high-resolution and accurate spatial information on the river turbidity.

무로마치 시대 초물(抄物)의 비음운미(鼻音韻尾)에 접속하는 비연탁어(非連濁語) 연구

이승영 한국일본어문학회 2018 日本語文學 Vol.77 No.-

In this study, I considered the relationship between words connecting forward nasal rhyme and tone focusing on non continuous turbidity words of Chinese words where continuous turbidity phenomenon did not occur. The results as follows. Firstly, continuous turbidity words and non continuous turbidity words followed by tone were 170 letters at continuous turbidity words and 880 letters at non continuous turbidity words. This meant the thing followed by nasal sound necessarily did not make continuous turbidity. Secondly, among repulsion, tongue nasal sound[n]was most popular and the next was [ŋ]. Lastly, the numbers of example words about tone of words connecting forward and tone with continuous turbidity, there were lots of continuous turbidity cases followed by falling tone. On the other hands, tone of non continuous turbidity words connecting forward did not have few Chinese characters. Tones of non continuous turbidity words did have little relationship with continuous turbidity of the words.

Sea Water Turbidity Variability and Relation to Tides and Environmental Factors in the Korean Coastal Region of the Yellow Sea

Kim Su-Ran,Kim Tae-Sung,박경애,Park Jaejin,Lee Moon Jin,Byun Do-Seong 한국해양과학기술원 2024 Ocean science journal Vol.59 No.4

This study analyzes sea surface water turbidity variability in the coastal region of the Yellow Sea and investigates the relationships with environmental factors. By applying spectral analysis, harmonic analysis, wavelet transformation, and multivariate linear regression to in situ measurements of seawater turbidity data, we examined the temporal turbidity variability and the fractional contributions of tidal currents and atmospheric components to turbidity variations. A multivariate linear regression was used to determine the daily variations in the fractional contributions of tidal currents and atmospheric components to turbidity. The results showed that seawater turbidity exhibited dominant fluctuations corresponding to major tidal harmonics (M2, S2, K1, and O1), along with shallow-water tides (MS4 and M4) and the M2 variation-related semi-diurnal tides (H1 and H2). The amplitudes of turbidity variations associated with these shallow-water tides and semi-diurnal tides demonstrated a linear relationship with those of the tides, with a rate of 0.24 NTU cm−1. This rate was four times greater than the rate of 0.06 NTU cm⁻1 observed for the major tides, addressing the important roles of non-linear tidal processes in shallow regions. In addition, an inertial motion in coastal turbidity (19.56 h) was detected when external forces were relatively weak. The impact of tidal currents on turbidity fluctuations was significantly reduced during typhoon periods due to pronounced atmospheric influences. Investigations of high-resolution Sentinel-2 turbidity over the past 6 years (2018–2023) illustrated more distinctive responses to extreme environmental conditions. This study is expected to enhance the comprehensive understanding of turbidity fluctuations and their linkages to tidal currents and atmospheric conditions in the Yellow Sea.

팔당호에서 수중 탁도의 일 변동과 고탁수의 입자 분포

신재기 ( Sin Jae Gi ),강창근 ( Kang Chang Geun ),황순진 ( Hwang Sun Jin ) 한국하천호수학회 2003 생태와 환경 Vol.36 No.3

Daily monitoring was conducted to elucidate the changes in turbidity and distribution of particles in the turbid water of a river-type reservoir (Paltang Reservoir) from 1999 to 2001. Water turbidity and the particle distribution of turbid water were principally affected by meteorological factors particularly rainfall patterns and hydrological factors such as inflow and outflow. The mean concentration of turbidity was constant each year, with the concentration of less than 10NTU accounting for 85%. Seasonal characteristics were remarkable, with winter and spring having <5 NTU, autumn 5~10 NTU, and summer >20NTU. Unlike hydrological changes, maximum turbidity was observed from late July to early August and continuously increased from 1999 to 2001. In particular, the maximum turbidity of reservoirs remarkably increased toward the lower part of reservoir in 2001. Discharge and turbidity increased or decreased slowly in 1999; in contrast, turbidity rapidly increased in the early rainfall period of 2000 and 2001 but later decreased as discharge increased. In the particles of turbid water, clay ingredients were more densely distributed and more dominant in all stations. Of the total particles in turbid water, clay constituted 63.9%~66.6% and silt 33.4~36.1% to account for a combined total of 98.1~100%. Sand made up less than 1.1%. The turbidity of river-type reservoir was also found to be mainly affected by the biomass of plankton in a non-rainfall period. During a rainfall period, however, the quantity and relative ratio of inorganic particles depending on the soil components affected turbidity.

소양강댐 상류 탁도와 저서성 대형무척추동물 군집의 관계 분석

최미경,류제완,안종호 응용생태공학회 2024 Ecology and resilient infrastructure Vol.11 No.4

본 연구는 환경부에서 제공하는 생물측정망 데이터를 활용하여 탁수가 수생태계에 미치는 영향을 분석하기 위하여, 소양강댐 상류를 대상으로 탁수와 저서성 대형무척추동물 군집의 상관분석을 수행하였다. 탁수 관련 변수로는 생물조사 시기탁도 농도, 생물조사 시기 이전 6개월 간 탁도의 농도와 지속시간을 고려한 탁도누적합, 탁도 20, 40, 100 NTU 초과 기간, 탁도 최대값을 사용하였다. 저서성 대형무척추동물 군집에 관련된 변수로는 총 개체밀도 및 종수, 섭식 별, 무리 별 개체밀도및 개체비율로 설정하였다. 상관분석 결과, 탁도와 저서성대형무척추동물 군집 간의 높은 상관관계를 도출하는 것은 어려웠으나일부 변수에서 유의한 상관관계가 확인되었다. 탁도누적합이 증가할수록 주워먹는 무리(Collector-Gatherers), 걸러먹는 무리(Collector-Filerers), 긁어먹는 무리(Scrapers), 하루살이목(Ephemeroptera), 날도래목(Trichoptera)의 개체밀도는 감소하는 경향을 보였다. 반면 탁도 증가와 하루살이목의 개체밀도 점유 비율은 약한 상관성을 보였으나 통계적으로 유의한 증가 경향을나타냈다. 본 연구는 향후 데이터 신뢰도 분석 및 연구 대상 지역 확대를 통하여 탁수에 의한 수생태계 영향 평가 기술 개발에기여하고자 한다. This study aims to analyze the impact of turbidity on aquatic ecosystems by proposing turbidity-related and ecosystem-related variables and conducting correlation analyses. The study area includes the upper stream of Soyanggang Dam (Inbukcheon, Naerincheon, and Soyanggang) utilizing turbidity data and biomonitoring data for benthic macroinvertebrates. Appropriate variables for analysis were proposed, and correlation analyses were performed. The results indicate that among turbidity-related variables, cumulative turbidity can serve as a representative metric. As cumulative turbidity increases, the population density of functional feeding groups such as Collector-Filters, Collector-Gatherers, and Scrapers tends to decrease. Additionally, the population densities of Ephemeroptera (mayflies) and Trichoptera (caddisflies) also decline. Conversely, as cumulative turbidity increases, the proportional density of Ephemeroptera rises, suggesting an increase in the relative abundance of Collector-Gatherers, whereas the proportions of Collector-Filters and Scrapers decrease. Future research involving reliability analysis of the data and an expansion of study areas is necessary to contribute to the development of evaluation techniques for assessing the impacts of turbidity on aquatic ecosystems.

탁도에 따른 음료의 미각 인지: 20, 30대 소비자를 중심으로

김태수 ( Taesu Kim ),최경아 ( Kyungah Choi ),석현정 ( Hyeon-jeong Suk ) 한국감성과학회 2017 감성과학 Vol.20 No.2

This research investigated the cross-modal correspondence between the turbidity and taste of beverages. For an empirical study, we employed two types of achromatic beverages: rice wine and a soft drink. The turbidity of each drink varied between 0.0625~32 g/L, and 0.0078~4 g/L, respectively, and the stimuli were prepared in ten levels according to cognitive turbidity. In the study, participants (N=35) rated each drink stimulus using a 3-point Likert scale with regard to five basic tastes: sweet, salty, bitter, sour, and preferred. In addition, six specific tastes were included that deliberately describe rice wine and the soft drink. Three were yeasty, alcoholic, and astringent for the rice wine, and the other three were creamy, bubbly, and syrupy for the soft drink. Based on participants` assessments, the turbidity of rice wine is highly positively correlated with all five basic tastes. In contrast, the turbidity of the soft drink was positively correlated with sour only. Concerning preference, the most preferred turbidity of rice wine was 4.6~20 g/L, which is close to the turbidity of existing products on the market. Furthermore, except for astringent and syrupy, all tastes were influenced by the turbidity, which implies the potential of turbidity as a new visual parameter to communicate the taste experience of beverages.

Py_STPS모형과 관측자료를 활용한 탁도역추적기법 개발

여홍구,이남주 응용생태공학회 2023 Ecology and resilient infrastructure Vol.10 No.4

차별적 특징을 갖지 않는 탁도 측정자료에 대한 역추적기법을 개발하고자 지천의 상류와 하류에 위치한 수질자동측정점에서측정된 실시간 탁도자료와 Py_STPS모형을 사용하여 지천의 유입탁도를 예측하는 세 가지 탁도역추적기법을 비교하였다. 유하시간을고려한 탁도부하량 단순보존 방법, 유하시간을 고려한 상류경계의 유량을 하류경계의 유량으로 사용하는 방법, 탁도 유발물질의거동특성을 반영하기 위해 내부반응률을 도입한 방법 세 가지 탁도 역추적기법을 적용하였다. 세 가지 역추적모형의 적용 결과, 내부반응률을 도입한 역추적기법의 결과가 가장 우수함을 확인할 수 있었다. In order to develop a backtracking technique for turbidity measurement data without discriminatory characteristics, three turbidity backtracking techniques for predicting inflow turbidity of a stream were compared using real-time turbidity data measured at automatic water quality measurement points located upstream and downstream of the stream and the Py_STPS model. Three turbidity backtracking techniques were applied: 1) simple preservation method of turbidity load considering flow time, 2) a method of using the flow rate at the upstream boundary considering the flow time as the flow rate at the downstream boundary, 3) method of introducing internal reaction rate to reflect the behavior characteristics of turbidity-causing substances. As a result of applying the three backtracking models, it was confirmed that the backtracking technique that introduced the internal reaction rate had the best results.

해양 실측 및 위성자료를 활용한 한반도 서해 연안탁도 변화와 수직 수중시야 연구

박재진,김태성,박경애,김용명 한국지구과학회 2025 한국지구과학회지 Vol.46 No.2

최근 한반도 주변 해역에서 해상사고로 인한 인명피해가 증가함에 따라 실종자 수색 및 구조 활동을 지원하기위한 수중환경 정보 산출 기술 개발의 필요성이 대두되고 있다. 끊임없이 변화하는 해양환경 속에서 수중시야를 예측하는 것은 매우 중요한 과제이다. 본 연구에서는 인공위성 영상과 현장실험 자료를 활용하여 탁도와 수중시야 간의 상관성을 분석하고, 한반도 서해 연안에 적합한 수중시야 산출 알고리즘을 제시하고자 한다. 이를 위해 대천항 인근 해역의두 정점을 선정하여 탁도 센서와 세키디스크를 이용해 깊이에 따른 탁도 및 수중시야를 측정하였으며, 동시에 고해상도인공위성 영상을 수집하여 표층 원격반사도 자료를 획득하였다. 또한 서해 연안에서의 탁도 변화에 따른 수중시야의 공간 분포를 비교하기 위해 Sentinel-2 위성의 560 nm 반사도를 활용하여 연구 해역의 탁도를 산출하고, 실측 탁도와 수중시야 간의 상관성을 분석하였다. 연구 결과, 서해 연안에서는 2 .0- 3.0NTU 범위의 탁도가 분포하였으며, 수중거리는1.5-3.5 m 사이의 값을 나타냈다. 특히, 만 지형이나 섬 주변에서는 상대적으로 낮은 수중시야가 관측된 반면, 대천해수욕장 해안선을 따라서는 약 3.0m 이상의 높은 수중시야를 보였다. 본 연구를 통해 실측 및 원격탐사 자료를 활용한수중시야 산출 가능성을 확인하였으며, 위 결과는 향후 해상 실종자 수색 지원을 위한 기초 자료로 활용될 것으로 기대된다. Recently, the increasing number of maritime accidents around the Korean Peninsula has highlighted the need todevelop underwater environmental information retrieval technologies to support search and rescue operations for missingpersons at sea. Predicting underwater visibility in rapidly changing marine environments is a critical challenge. This studyaims to analyze the correlation between turbidity and underwater visibility using satellite imagery and in-situ experimentaldata and proposes a turbidity-based underwater visibility retrieval algorithm suitable for the western coast of the KoreanPeninsula. To achieve this, turbidity and underwater visibility were measured at two stations near Daecheon Port using aturbidity sensor and Secchi disk, and high-resolution satellite images were simultaneously collected to obtain surfaceremote reflectance data. In addition, turbidity in the study area was retrieved using Sentinel-2 560 nm reflectance satelliteimagery, and the correlation between the measured turbidity and underwater visibility was analyzed to examine the spatialdistribution of underwater visibility based on turbidity variations in western coastal waters. The results showed thatturbidity in the western coastal waters ranged from 2.0 to 3.0 NTU, whereas underwater visibility varied from 1.5 to3.5 m. Specifically, lower underwater visibility was observed in bays and around islands, whereas higher underwatervisibility (approximately 3.0 m) was found along the Daecheon Beach shoreline. This study confirms the feasibility ofretrieving underwater visibility using in-situ and remote-sensing data, which is expected to serve as a fundamentalresource for supporting search and rescue operations in maritime accidents.

Reduction in turbidity of Indian lakes through satellite imagery during COVID‑19 induced lockdown

Ashish Joshi,Shefali Agrawal 대한공간정보학회 2022 Spatial Information Research Vol.30 No.6

The lakes of India are getting significantly polluted due to the rapid growth of industries, plastics, and anthropogenic waste. Due to the non-functioning of the industries and human activities during the COVID-19 pandemic lockdown, industrial and other waste going to the lakes was significantly reduced. Moreover, with the reduction of human activities and tourism in the cities and lakes, anthropogenic pollution in the lakes was also reduced. Turbidity is the key indicator of water pollution in the lakes. It has a direct relationship with surface water reflectance and can be estimated through satellite imagery. In this paper, the relative comparison of turbidity values of five Indian lakes in the Rajasthan state was done through Satellite imagery of Sentinel-2 during the pre-lockdown and lockdown period. The relative turbidity is also calculated through reflectance values of Satellite images and then the empirical method is applied to the reflectance values of the red band of Sentinel-2 & Landsat-8 data to estimate the turbidity. Relative comparisons of turbidity values estimated through satellite imagery during the pre-lockdown and lockdown period showed that the turbidity of lakes was reduced in Kaylana Lake (49.6%), Fatehsagar Lake (55.4%), Pichola Lake (54.3%), Rajsamand Lake (58.3%), and Man Sagar Lake (44.8%) during the lockdown period. Spectral curve analysis also showed that there was a decrease in the surface water reflectance in all five lakes and this indicates the reduction in the turbidity of the water during the lockdown period.

Investigation of the Performance of Chitosan as a Coagulant for Flocculation of Local Clay Suspensions of Different Turbidities

Madhukar V. Jadhav,Yogesh S. Mahajan 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.2

In the present research, the effectiveness of chitosan as a natural coagulant for turbidity removal was investigated by the use of jar test. Tests were carried out on synthetic turbid water prepared from local clay, with high (314.4 NTU), medium (146.8 NTU) and low (34.2 NTU) turbidity. Experiments were also performed with chitosan as a coagulant aid. Consequence of pH, effect of settling time on residual turbidity was also studied. In present Research New Technique was tried which adopts two sequent treatments that used coagulation, flocculation and sedimentation processes under certain operating conditions. Results show that chitosan produces an appreciable removal of turbidity at approximately neutral pH. With conventional process maximum removal of turbidity was 61.9,84.1 and 94.0% with residual turbidities of 13.0, 23.3 and 18.8 NTU for low, medium and high turbid water at dose of 1.5 mg/L. In the experiments with chitosan as a coagulant aid, the results were very promising; the residual turbiditities recorded were 8.6, 4.8 and 5.8 NTU for initial turbidities of 34.2, 146.8 and 314.4 NTU. The experimental results of present study proved that the turbidity removal efficiency of new technique was superior than that of conventional process which meets WHO drinking water guidelines. By this technique removal efficiency has increased from 5 to 28% at settling time of 30 minutes with around 75% saving in alum dose. Also sludge produced was less voluminous and readily biodegradable. There was minor change in pH of treated water. Floc formed with chitosan was coarse and readily settleable.