• Title/Summary/Keyword: Bi-seasonal analysis

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Forest Vertical Structure Mapping from Bi-Seasonal Sentinel-2 Images and UAV-Derived DSM Using Random Forest, Support Vector Machine, and XGBoost

  • Young-Woong Yoon;Hyung-Sup Jung
    • Korean Journal of Remote Sensing
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    • v.40 no.2
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    • pp.123-139
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    • 2024
  • Forest vertical structure is vital for comprehending ecosystems and biodiversity, in addition to fundamental forest information. Currently, the forest vertical structure is predominantly assessed via an in-situ method, which is not only difficult to apply to inaccessible locations or large areas but also costly and requires substantial human resources. Therefore, mapping systems based on remote sensing data have been actively explored. Recently, research on analyzing and classifying images using machine learning techniques has been actively conducted and applied to map the vertical structure of forests accurately. In this study, Sentinel-2 and digital surface model images were obtained on two different dates separated by approximately one month, and the spectral index and tree height maps were generated separately. Furthermore, according to the acquisition time, the input data were separated into cases 1 and 2, which were then combined to generate case 3. Using these data, forest vetical structure mapping models based on random forest, support vector machine, and extreme gradient boost(XGBoost)were generated. Consequently, nine models were generated, with the XGBoost model in Case 3 performing the best, with an average precision of 0.99 and an F1 score of 0.91. We confirmed that generating a forest vertical structure mapping model utilizing bi-seasonal data and an appropriate model can result in an accuracy of 90% or higher.

Development of the Seasonal Korean Aviation Turbulence Guidance (KTG) System Using the Regional Unified Model of the Korea Meteorological Administration (KMA) (기상청 통합지역모델을 이용한 계절 한국형 항공난류 예측시스템(계절-KTG) 개발)

  • Lee, Dan-Bi;Chun, Hye-Yeong
    • Atmosphere
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    • v.24 no.2
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    • pp.235-243
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    • 2014
  • Sources of aviation turbulence vary through the seasons, especially in the East Asia including Korean peninsula, associated primarily with the changes in the jet/front system and convective activities. For this reason, a seasonal Korean aviation Turbulence Guidance (KTG) system (seasonal-KTG) is developed in the present study by using pilot reports (PIREPs) and analysis data of the operational Unified Model (UM) of the Korea Meteorological Administration (KMA) for two years between June 2011 and May 2013. Twenty best diagnostics of aviation turbulence in each season are selected by the method of probability of detection (POD) using the PIREPs and UM data. After calculating a weighting value of each selected diagnostics using their area under curve (AUC), the 20 best diagnostics are combined with the weighting scores into a single ensemble-averaged index by season. Compared with the current operational-KTG system that is based on the diagnostics applying all seasons, the performances of the seasonal-KTG system are better in all seasons, except in fall.

Comparative Analysis of Baseflow Separation using Conventional and Deep Learning Techniques

  • Yusuff, Kareem Kola;Shiksa, Bastola;Park, Kidoo;Jung, Younghun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2022.05a
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    • pp.149-149
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    • 2022
  • Accurate quantitative evaluation of baseflow contribution to streamflow is imperative to address seasonal drought vulnerability, flood occurrence and groundwater management concerns for efficient and sustainable water resources management in watersheds. Several baseflow separation algorithms using recursive filters, graphical method and tracer or chemical balance have been developed but resulting baseflow outputs always show wide variations, thereby making it hard to determine best separation technique. Therefore, the current global shift towards implementation of artificial intelligence (AI) in water resources is employed to compare the performance of deep learning models with conventional hydrograph separation techniques to quantify baseflow contribution to streamflow of Piney River watershed, Tennessee from 2001-2021. Streamflow values are obtained from the USGS station 03602500 and modeled to generate values of Baseflow Index (BI) using Web-based Hydrograph Analysis (WHAT) model. Annual and seasonal baseflow outputs from the traditional separation techniques are compared with results of Long Short Term Memory (LSTM) and simple Gated Recurrent Unit (GRU) models. The GRU model gave optimal BFI values during the four seasons with average NSE = 0.98, KGE = 0.97, r = 0.89 and future baseflow volumes are predicted. AI offers easier and more accurate approach to groundwater management and surface runoff modeling to create effective water policy frameworks for disaster management.

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Seasonal distribution of marine organisms in the surface layer around nuclear power plants using acoustic (원자력발전소 주변 표층해역에 출현하는 해양생물의 계절별 음향산란 분포)

  • Eun-Bi MIN;Tae-Jong KANG;Yeongtae SON;Doo-Jin HWANG
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.60 no.1
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    • pp.9-17
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    • 2024
  • In this study, the seasonal distribution was surveyed using acoustic in the coastal waters around nuclear power plants. Acoustic surveys were conducted in June, September, December 2022, and March 2023 in the coastal waters of Uljin-gun. According to the results of this study, zooplankton were distributed at the depths from 0 m to 50 m in the waters around nuclear power plants. Zooplankton appeared in summer (June), autumn (September), and spring (March). In the survey area, fish were distributed at the depths from 25 m to 190 m, appearing in the summer (June), autumn (September), winter (December) and spring (March). The SV of zooplankton appearing in the survey area ranged from -98.0 dB to -78.0 dB, and it exhibited a one-class in the frequency distribution of SV. The SV of fish appearing in the survey area ranged from -36.0 dB to -35.0 dB and -98.0 dB to -53.0 dB, and it exhibited two-class in the frequency distribution of SV.

A multi-scale analysis of the interdecadal change in the Madden-Julian Oscillation (MJO의 다중스케일 분석을 통한 수십년 변동성)

  • Lee, Sang-Heon;Seo, Kyong-Hwan
    • Atmosphere
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    • v.21 no.2
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    • pp.143-149
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    • 2011
  • A new multi-timescale analysis method, Ensemble Empirical Mode Decomposition (EEMD), is used to diagnose the variation of the MJO activity determined by 850hPa and 200hPa zonal winds from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis data for the 56-yr period from 1950 to 2005. The results show that MJO activity can be decomposed into 9 quasi-periodic oscillations and a trend. With each level of contribution of the quasi-periodic oscillation discussed, the bi-seasonal oscillation, the interannual oscillation and the trend of the MJO activity are the most prominent features. The trend increases almost linearly, so that prior to around 1978 the activity of the MJO is lower than that during the latter part. This may be related to the tropical sea surface temperature(SST). It is speculated that the interdecadal change in the MJO activity appeared in around 1978 is related to the warmer SST in the equatorial warm pool, especially over the Indian Ocean.

Optical Properties of Aerosol at Gongju Estimated by Ground-based Measurements Using Sky-radiometer (스카이라디오미터(Sky-radiometer)로 관측된 공주지역 에어로솔의 광학적 특성)

  • Kwak, Chong-Heum;Suh, Myoung-Seok;Kim, Maeng-Ki;Kwak, Seo-Youn;Lee, Tae-Hee
    • Journal of the Korean earth science society
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    • v.26 no.8
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    • pp.790-799
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    • 2005
  • We investigate the optical properties of aerosols over Gongju by an indirect method using the pound measurement, Sky-radiometer. The analysis period is from January to December, 2004. Skyrad. pack.3 is used to estimate the optical properties, such as the aerosol optical thickness (AOT), single scattering albedo (SSA), ${\AA}ngstron$ exponent $({\alpha})$ and size distribution, of aerosols from the ground measured radiance data. And qualify control is applied to minimize the cloud-contaminated data and improve the quality of analysis results. The 12-month average of AOT, ${\alpha}$, and SSA are 0.46, 1.14, and 0.91, respectively. The average volume spectra of aerosols shows a bi-modal distribution, the first peak at fine mode and the second peak at coarse mode. AOT and coarse particles clearly increases while SSA decreases during the Asian dust events. The optical properties of aerosols at Gongju vary with?seasons, but those are not influenced by the wind direction.

Relationship between Physico-Chemical Factors and Chlorophyll-$a$ Concentration in Surface Water of Masan Bay: Bi-Daily Monitoring Data (마산만 표층수에서 물리-화학적 수질요인과 엽록소-$a$ 농도 사이의 관계: 격일 관측 자료)

  • Jung, Seung-Won;Lim, Dhong-Il;Shin, Hyeon-Ho;Jeong, Do-Hyun;Roh, Youn-Ho
    • Korean Journal of Environmental Biology
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    • v.29 no.2
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    • pp.98-106
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    • 2011
  • In order to investigate water quality factors controlling chlorophyll-$a$ concentrations, the by-daily monitoring was conducted from February to November 2010 in 4 stations of Masan Bay. Seasonal variability in physico-chemical factors was mainly controlled by freshwater loading as a result of precipitation: chemical oxygen demand, suspended solids and nutrient concentrations rapidly increase during the heavy rainy season, whereas they decrease in the dry season. From late winter to mid spring, phosphorus and silica sources relative to Redfield ratio were probably functioned as limiting factor for phytoplankton flourishing in surface waters, but nitrogen concentration during mid-spring to autumn might be responsible for the increase of phytoplankton biomass. The multiple regression analysis revealed that variations in chlorophyll-$a$ concentration may be strongly correlated with changes of water temperature, chemical oxygen demand, dissolved inorganic phosphorus in spring, and salinity, chemical oxygen demand and precipitation in summer. Consequently, in the Masan Bay, a heavy rainfall event is an important factor to determine changes of biotic and abiotic factors, and in addition the dynamics of chlorophyll-$a$ concentration are strongly affected by changes of hydrological factors, especially water temperature, precipitation and nutrients.

The food Choices and Dietary Preferences of College Women (여대생(女大生)의 음식(飮食) 선택(選擇) 및 기호(嗜好) 성향(性向))

  • Kim, Young-Ja
    • Journal of Nutrition and Health
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    • v.9 no.3
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    • pp.35-45
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    • 1976
  • To investigate the food choices and Dietary Preferences of College Women the number of dishes sold and the sales of the midmeal at the Student Cafeteria, Ewha Womans University were recorded for the fiscal year of 1974; and the observations were made on two consecutive days (June 3rd and 4th, 1974)on what a person has chosen which and how many dishes. The relationship between the number of the consecutive days and the number of foods chosen were treated as Chi square analysis. The results of the food choices and dietary preferences of College Women were as follows: 1. Breads and rice cakes, vegetable dishes, milk and milk products, rice dishes, soups, meat, fish, poultry and eggs, Kimchis and one dish meal were chosen highly; and beverages, stews, and soybeans and soybean products were chosen negligibly. 2. One dish meals, vegetable dishes, meat, fish, poultry and eggs, milk and milk products showed the highest sales volume during the year; rice dishes, breads and rice cakes were the second highest in sales amount; fried foods, snacks and Kimchis showed the range of $3{\sim}6%$ of the total sales; and the beverages, stews, soybean and soybean products were the lowest in sales amount. 3. Seasonal differences were noticed on some dishes. Breads add rice cakes, milk and milk products showed the high selections from March to November and the low, during December to February. Stews, Kimchis, beverages were kept low except sudden rise on February. One dish meal and rice dishes showed almost same level during the year but on February the slight increase were noticed; even level were kept on meat group except the increase to $13{\sim}16%$ on July and December. Fried foods were kept on similar level during the year except the increase on June. Snacks and fruits showed low selections on March, April, November and December and higher at summer. Vegetables, soups, soybean and soybean products showed no different fluctuations in selections during the year. 4. Rolls, salads, milk, hamburgers, fried vegetables, rice with mired vegetables(Bi-bim-bab), and Nang-myun were the single dishes chosen most frequently. 5. There is significant relationship at 0.05 level between the consecutive days and the number of foods chosen. It is concluded that about 50% of the population has taken one item of dishes. The popular combinations were one dish meal and soup or Kimchi; noodles and salads or fried vegetables. It is suggested to set up choice menus with the daily variations, cyclical variations and with the invariable ones; and to recommend one dish meal, breads, partial meals for school lunch; and to study to improve one dish meal, vegetable dishes and fried foods, which are new and inexpensive products. It is also suggested that the feeding of the college students should have to lead the people to the goal that the nutrition education is desired.

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A Literature Review of Fish Feeding Research in the Coast - Estuary Areas of Korean Peninsula (우리나라 연안-하구에 서식하는 어류의 식성 관련 연구 현황)

  • Jo, Hyunbin;Kim, Dong-Kyun;Park, Kiyun;Lee, Wan-Ok;Kwak, Ihn-Sil
    • Korean Journal of Ecology and Environment
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    • v.52 no.2
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    • pp.126-135
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    • 2019
  • We carried out a literature review of fish food sources research in the coast - estuary areas of Korean peninsula for the last fifty years(1969~2018). A total of 101 research papers were reviewed, of which 81 were published in domestic journals, 7 were puliched in domestic reports and 14 were published in international journals. When divided into the decade periods, 21 papers (19.4%) between 1990 and 1999 and 26 papers (24.1%) between 2000 and 2009, and 42 papers (48.1%) were published in 2010 and 2018, respectively. When divided into the survey area by a bearing (East sea, South-East sea, South Sea, and West Sea), 65 papers(69.1%) were carried out in the South Sea. Followed by 13 papers (13.8%) in the East Sea and 8 papers (8.5%) in the West Sea and the South-East Sea, respectively. The surveyed area was dominant in Gwangyang Bay (18 papers; 24.3%), followed by Gadeok-do (8 papers; 10.8%). Of the diversity indices, 14 indices were used to calculate the ecological status. The dominant indices were IRI(Index of relative importance), Pi(Prey-specific abundance) followed by E (electivity index) and Bi (dietary breadth index). A total of 11 statistical methods were used to find feeding strategy. The correlation analysis and Bray-Curtis similarity matrix were applied most frequently. In terms of ecological research topics, the papers focused on seasonal or spatial differences before 2000. Since 2000, specifically, the international journal papers have been published based on competition, sympatric, niche overlap and other ecological topics.