• Title/Summary/Keyword: Determination method

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Estimation of Nondestructive Rice Leaf Nitrogen Content Using Ground Optical Sensors (지상광학센서를 이용한 비파괴 벼 엽 질소함량 추정)

  • Kim, Yi-Hyun;Hong, Suk-Young
    • Korean Journal of Soil Science and Fertilizer
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    • v.40 no.6
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    • pp.435-441
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    • 2007
  • Ground-based optical sensing over the crop canopy provides information on the mass of plant body which reflects the light, as well as crop nitrogen content which is closely related to the greenness of plant leaves. This method has the merits of being non-destructive real-time based, and thus can be conveniently used for decision making on application of nitrogen fertilizers for crops standing in fields. In the present study relationships among leaf nitrogen content of rice canopy, crop growth status, and Normalized Difference Vegetation Index (NDVI) values were investigated. We measured Green normalized difference vegetation index($gNDVI=({\rho}0.80{\mu}m-{\rho}0.55{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.55{\mu}m)$) and NDVI($({\rho}0.80{\mu}m-{\rho}0.68{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.68{\mu}m)$) were measured by using two different active sensors (Greenseeker, NTech Inc. USA). The study was conducted in the years 2005-06 during the rice growing season at the experimental plots of National Institute of Agricultural Science and Technology located at Suwon, Korea. The experiments carried out with randomized complete block design with the application of four levels of nitrogen fertilizers (0, 70, 100, 130kg N/ha) and same amount of phosphorous and potassium content of the fertilizers. gNDVI and rNDVI increased as growth advanced and reached to maximum values at around early August, G(NDVI) were a decrease in values of observed with the crop maturation. gNDVI values and leaf nitrogen content were highly correlated at early July in 2005 and 2006. On the basis of this finding we attempted to estimate the leaf N contents using gNDVI data obtained in 2005 and 2006. The determination coefficients of the linear model by gNDVI in the years 2005 and 2006 were 0.88 and 0.94, respectively. The measured and estimated leaf N contents using gNDVI values showed good agreement ($R^2=0.86^{***}$). Results from this study show that gNDVI values represent a significant positive correlation with leaf N contents and can be used to estimate leaf N before the panicle formation stage. gNDVI appeared to be a very effective parameter to estimate leaf N content the rice canopy.

Calculation Method of Oil Slick Area on Sea Surface Using High-resolution Satellite Imagery: M/V Symphony Oil Spill Accident (고해상도 광학위성을 이용한 해상 유출유 면적 산출: 심포니호 기름유출 사고 사례)

  • Kim, Tae-Ho;Shin, Hye-Kyeong;Jang, So Yeong;Ryu, Joung-Mi;Kim, Pyeongjoong;Yang, Chan-Su
    • Korean Journal of Remote Sensing
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    • v.37 no.6_1
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    • pp.1773-1784
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    • 2021
  • In order to minimize damage to oil spill accidents in the ocean, it is essential to collect a spilled area as soon as possible. Thus satellite-based remote sensing is a powerful source to detect oil spills in the ocean. With the recent rapid increase in the number of available satellites, it has become possible to generate a status report of marine oil spills soon after the accident. In this study, the oil spill area was calculated using various satellite images for the Symphony oil spill accident that occurred off the coast of Qingdao Port, China, on April 27, 2021. In particular, improving the accuracy of oil spill area determination was applied using high-resolution commercial satellite images with a spatial resolution of 2m. Sentinel-1, Sentinel-2, LANDSAT-8, GEO-KOMPSAT-2B (GOCI-II) and Skysat satellite images were collected from April 27 to May 13, but five images were available considering the weather conditions. The spilled oil had spread northeastward, bound for coastal region of China. This trend was confirmed in the Skysat image and also similar to the movement prediction of oil particles from the accident location. From this result, the look-alike patch observed in the north area from the Sentinel-1A (2021.05.01) image was discriminated as a false alarm. Through the survey period, the spilled oil area tends to increase linearly after the accident. This study showed that high-resolution optical satellites can be used to calculate more accurately the distribution area of spilled oil and contribute to establishing efficient response strategies for oil spill accidents.

Sentinel-1 SAR image-based waterbody detection technique for estimating the water storage in agricultural reservoirs (농업저수지의 저수량 추정을 위한 Sentinel-1 SAR 영상 기반 수체탐지 기법)

  • Jeong, Jaehwan;Oh, Seungcheol;Lee, Seulchan;Kim, Jinyoung;Choi, Minha
    • Journal of Korea Water Resources Association
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    • v.54 no.7
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    • pp.535-544
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    • 2021
  • Agricultural water occupies 48% of water demand, and management of agricultural reservoirs is essential for water resources management within agricultural basins. For more efficient use of agricultural water, monitoring the distribution of water resources in agricultural reservoirs and agricultural basins is required. Therefore, in this study, three threshold determination methods (i.e., fixed threshold, Otsu threshold, Kittler-Illingworth (KI) threshold) were compared to detect terrestrial water bodies using Sentinel-1 images for 3 years from 2018 to 2020. The purpose of this study was to evaluate methods for determining threshold values to more accurately estimate the reservoir area. In addition, by analyzing the relationship between the water surface and water storage at the Edong, Gosam, and Giheung reservoirs, water storage based on the SAR image was estimated and validated with observations. The thresholding method for detecting a waterbody was found to be the most accurate in the case of the KI threshold, and the water storage estimated by the KI threshold indicated a very high agreement (r = 0.9235, KGE' = 0.8691). Although the seasonal error characteristics were not observed, the problem of underestimation at high water levels may occur; the relationship between the water surface and the water storage could change rapidly. Therefore, it is necessary to understand the relationship between the water surface area and water storage through ground observation data for a more accurate estimation of water storage. If the use of SAR data through water resources satellites becomes possible in the future, based on the results of this study, it is judged that it will be beneficial for monitoring water storage and managing drought.

Nondestructive Methods for the Detection of Internal Decay and the Vitality Measurement of Old-Giant Trees (노거수 활력 측정 및 내부 부후 검출을 위한 비파괴검사법)

  • Gao, Yuliang;Cha, Byeong Jin
    • Korean Journal of Heritage: History & Science
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    • v.42 no.1
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    • pp.144-157
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    • 2009
  • Nondestructive methods to check the vitality of trees and to find out internal decay of old-giant trees include the use of electrical resistance, ultrasound transmission time, microdrilling, and infrared thermography etc. Among these, ultrasound transmission offers some advantages compared to others such as it is an entirely nondestructive detection method and it can be applied to very big trees. However, the ultrasound equipment is comparatively expensive and not broadly spread yet. On the other hand, Shigometer is versatile to be applied to check vitality of the tree and find out internal decay. Electrical conductivity of plant tissues is a very useful characteristics to determine the vitality and internal decay of trees. Electrical resistance of cambial area tells about the vitality of a tree and electrical resistance of heartwood reveals discoloration or decay of it. For determination of the vitality of the tree, the standard equation for calibration of measured electrical resistances should be developed by measuring and analyzing electrical resistance from at least 30-40 trees of the same species with that tree. All the factors, especially tree species, diameter of the stem, and temperature, which can altered the electrical resistance of trees, should be taken into consideration in the development of the equation. If the standard equation is developed for old-giant trees that we should conserve, it will be very useful. In addition, periodical and continued measuring of a certain tree will help to determine the condition of the tree by comparing the measurement with accumulated data of the tree. Measuring electrical resistance of wood might not require the standard equation. But it also needs to check electrical resistance of sound wood of the same tree species. If the stems that should be examined is thicker than 40cm, it is better to use the ultrasound measurement combined to Shigometer.

A Safety Survey on Pesticide Residues in Dried Agricultural Products (건조농산물의 잔류농약 안전성 조사)

  • Lee, Hyo-Kyung;Oh, Moon-Seog;Jeong, Jin-A;Kim, Ki-Yu;Lee, Seong-Bong;Kim, Han-Taek;Kang, Hyang-Ri;Son, Ji-Hee;Lee, Yun-Mi;Lee, Mi-Kyoung;Lee, Byoung-Hoon;Kim, Ji-Won;Park, Yong-Bae
    • Journal of Food Hygiene and Safety
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    • v.34 no.4
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    • pp.340-347
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    • 2019
  • We performed a safety survey on residual pesticides in dried agricultural products. A total of 110 samples of dried agricultural products distributed in Gyeonggi-do were analyzed for 263 pesticides according to multi class pesiticide multiresidue method. Ten types of pesticides were detected in 10 samples. Chlorpyrifos was detected in Ricinus communis leaves, chlorpyrifos, hexaconazole, pyridalyl in Chwinamul (wild aster), diniconazole, isoprothiolane, lufenuron in radish leaves, hexaconazole in Cirsium setidens (Korean thistle), bifenthrin, and chlorothalonil, boscalid, and pyraclostrobin in pepper leaves. The detection rate of pesticides was 9.1%, and among these samples, one was detected over Maximum Residue Limits (MRLs). In the validation study, the values of limit of detection (LOD), limit of quantitation (LOQ), coefficient of determination ($R^2$) and recovery were in the range of 0.002~0.027 mg/kg, 0.006~0.083 mg/kg, 0.9964~1.0000 and 74.8~118.9%, respectively. The Positive List System (PLS) was newly introduced as part of the safety management of residual pesticide in agricultural products in Korea in 2019. With the application of the PLS, if the MRL is not established, 0.01 mg/kg limit is applied uniformly. In spite, these of strengthened residue limits, the MRLs of dried agricultural products are still insufficient. Therefore, this study could be utilized as basic data for the setting of proper MRLs.

Three-generation stories of the Joseon Dynasty, A Study on the Aspects of Family Therapy (삼대록계 국문 장편소설에 나타난 가족치료양상 연구 - 보웬의 이론에 근거하여 -)

  • Lee, hui su
    • (The)Study of the Eastern Classic
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    • no.49
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    • pp.393-430
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    • 2012
  • In this paper, Bowen's family therapy from the perspective of the theory, narrative analysis of Korean novels, three Regis - tration Subsection.Bowen's description of the individual's behavior is causing problems within the family of anxiety and self-differentiation using two variables. The home if problems or conflicts expressed in these works, the figures showed that the undifferentiated ego at the center of the problem. Undifferentiated ego character felt extreme anxiety when their alienation from the relationship of the family-oriented jeokjangja Undifferentiated ego to relieve anxiety and to consolidate their position in the family relationship, so people were strongly united with each other. Sohyunseongnok, Chossisamdaerok series structures and patterns of a series of domestic problems occur, "mother and son, self-differentiation self undifferentiated undifferentiated ego and self-differentiation mother son, mother and self-ego undifferentiated undifferentiatedcan be subdivided into the son '.Established a symbiotic relationship between them and the U.S. established the presence of a pattern, healer, depending on the deployment method depends narrative. And is divided accordingly, self-determination and to the Son, a son, a son to be born again through repentance of the execution. Depending on the presence or absence healer than what was described on the deployment structure differs. Undifferentiated ego and self undifferentiated mother son family therapist within the family, the problem is solved. Son, a son to repent and be born again, and that caused the problem. Ego Undifferentiated mother and son self-differentiation, undifferentiated ego and self-differentiation mother son home my healer in the absence son committed suicide and executions each tragedy occurred. Personal level, but occurred at home conflicts or problems about this when analyzing the Three-generation stories of the Joseon Dynasty, by applying the theory of Bowen's Family Therapy view dimension in the relationship between family were. Toughness or desire of any one individual, but serious conflicts and problems within the family, the institution of the family itself is the root cause was. And was able to reveal aspects of narrative flow, depending on the presence or absence of family therapists vary significantly depending on his role in the rest of the family comfort and peace determines whether the Three-generation stories of the Joseon Dynasty, received an important narrative of men and axis formation. In a gauze-like situation of this problem in the Three-generation stories of the Joseon Dynasty, a personal desire or toughness in confined without the dimension of the entire family. And extrinsic psychological approach against the background of the wall in the main narrative of the sufferings of women of Korean novels, approached significance.

The Characteristics of Traditional Representation in the Artist's Garden of the Garden Exposition seen through the Design Process (설계과정을 통해 본 정원박람회 작가정원의 전통재현 특성)

  • Lee, Song-Min;So, Hyun-Su
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.38 no.4
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    • pp.101-110
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    • 2020
  • This study was conducted through the analysis of literature and on-site research as a case study of 14 artists' gardens with traditional themes presented at the garden fair. With Focusing on the design process for determining traditional reproduction, the following characteristics and implications were derived by analyzing the design goals, selection of subjects for traditional reenactment, determination of methods for reproduction, and design stages of landscape components. First, the pattern of selecting traditional structures as subjects for reproduction in many artist gardens can be understood as an advantage of being suitable for narrow sites and having remarkable topic communicability. They directly delivered the design intent by adding the names of traditional structures such as Madang, Wool, Buttumak, Jangdokdae, Chuibyeong and Seokgasan. Works expressed indirectly, such as Wall, Korean Garden, Suwon, and Seoul craftsmen, have relatively weak topic communicability. There were also symbolic representations of objects to be reproduced, such as Seonbi, marginal spaces, and Pung-lyu. Second, while reproducing Hanok Madang, separate the gardens paved with grass and stone, the fortress wall of Suwon Hwaseong and the northwest Gongsimdon of the watchtower. Also the garden with a miniature version of the extraneous Yong-yeon and the garden, which was reproduced as a low decorative wall in the rest area based on Nakan-Eupseong Fortress, shows the need for a deep understanding of tradition. On the other hand, the reproducting works of choosing the location of the traditional garden, the Korean Garden showed the importance of systematic arrangement with the surrounding environment, the beauty of the space in the courtyard of Hanok, the beauty of the slowness enjoyed by the scholars and the reenactments of the Pung-lyu culture of Moonlight boating are not only imitating traditional structures but also spreading understanding of tradition to garden culture and sentiment. Third, there were many works that reconstructed the real-size traditional structure in a straightforward way in relation to design. The garden was divided into Chuibyeong and the living space was decorated with Buttumak, chimneys, and gardens, and facilities representing Gyeongbokgung Palace, Soswaewon, and Seoseokji were systemically arranged. However it recognized the importance of selecting the key design elements, constructing the elevation of the structure, and the sense of scale of the space from works that reproduced the large Suwon Hwaseong and Nakan-Eupseong in an abstract way. While there are examples gardens of Hanok yards and Bazawul, which are far from the original image among the gardens that chose the dismantling method, the Blank-space garden expressed only by a frame composed of cubes, and Seonbi's Sarangbang garden, that permeated the moonlight with many traditional structures are the positive examples. The Seoul Artisan Garden, Jikji Simche Garden and Pung-lyu Garden, which display modernly designed landscape components, need an explanation to understand the author's intention.

Determination of Freely Dissolved PAHs in Seawater around the Korean Peninsula Using High Speed Rotation-Type Passive Sampling Device (고속회전식 수동형 채집 장치를 이용한 한반도 주변해역에서의 자유용존상 PAHs 측정)

  • JANG, YU LEE;LEE, HYO JIN;JEONG, HAEJIN;JEONG, DA YEONG;KIM, NA YEONG;KIM, GI BEUM
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.26 no.1
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    • pp.37-48
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    • 2021
  • A new high speed rotation type-passive sampling device (HSR-PSD), which can rotate seawater at high speed and absorb easily and quickly the freely dissolved hydrophobic organic contaminants from seawater, was developed and then applied around the Korean Peninsula. Freely dissolved concentrations (Cfree) of polycyclic aromatic hydrocarbons (PAHs) were determined using the HSR-PSD with low density polyethylene (LDPE) sheets as a passive sampler. Furthermore, dissolved concentrations (Cdissolved) of PAHs in seawater were also obtained from high volume water sampling as a conventional method to account for actual bioavailability. When the LDPE sheets were rotated in the HSR-PSD at 900 rpm, PAHs with log KOW 3.4 ~ 5.2 were equilibrated between the LDPE and water in 5 hours. Although the high molecular weight PAHs with log KOW 5.6 ~ 6.8 was expected to be 2 to 30 days to reach the equilibrium, the Cfree of the PAHs at equilibrium could be corrected using performance reference compounds in 5 hours. Meanwhile, the total Cfree of PAHs were from 0.32 to 1.2 ng/L, which were higher than reported values in other oceans, but lower than in coastal water such as estuary, harbor, or shore. A bioavailability from the detected PAHs was highest at the sampling line near the dumping site of the Yellow Sea. Predicted residual concentrations in biota were relatively higher in offshore including the dumping site than in coastal regions.

Comparisons of Soil Water Retention Characteristics and FDR Sensor Calibration of Field Soils in Korean Orchards (노지 과수원 토성별 수분보유 특성 및 FDR 센서 보정계수 비교)

  • Lee, Kiram;Kim, Jongkyun;Lee, Jaebeom;Kim, Jongyun
    • Journal of Bio-Environment Control
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    • v.31 no.4
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    • pp.401-408
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    • 2022
  • As research on a controlled environment system based on crop growth environment sensing for sustainable production of horticultural crops and its industrial use has been important, research on how to properly utilize soil moisture sensors for outdoor cultivation is being actively conducted. This experiment was conducted to suggest the proper method of utilizing the TEROS 12, an FDR (frequency domain reflectometry) sensor, which is frequently used in industry and research fields, for each orchard soil in three regions in Korea. We collected soils from each orchard where fruit trees were grown, investigated the soil characteristics and soil water retention curve, and compared TEROS 12 sensor calibration equations to correlate the sensor output to the corresponding soil volumetric water content through linear and cubic regressions for each soil sample. The estimated value from the calibration equation provided by the manufacturer was also compared. The soil collected from all three orchards showed different soil characteristics and volumetric water content values by each soil water retention level across the soil samples. In addition, the cubic calibration equation for TEROS 12 sensor showed the highest coefficient of determination higher than 0.95, and the lowest RMSE for all soil samples. When estimating volumetric water contents from TEROS 12 sensor output using the calibration equation provided by the manufacturer, their calculated volumetric water contents were lower than the actual volumetric water contents, with the difference up to 0.09-0.17 m3·m-3 depending on the soil samples, indicating an appropriate calibration for each soil should be preceded before FDR sensor utilization. Also, there was a difference in the range of soil volumetric water content corresponding to the soil water retention levels across the soil samples, suggesting that the soil water retention information should be required to properly interpret the volumetric water content value of the soil. Moreover, soil with a high content of sand had a relatively narrow range of volumetric water contents for irrigation, thus reducing the accuracy of an FDR sensor measurement. In conclusion, analyzing soil water retention characteristics of the target soil and the soil-specific calibration would be necessary to properly quantify the soil water status and determine their adequate irrigation point using an FDR sensor.

Comparison of Microscopy and Pigment Analysis for Determination of Phytoplankton Community Composition: Application of CHEMTAX Program (식물플랑크톤 군집조성 파악을 위한 현미경관찰법과 지표색소분석법 비교 연구: CHEMTAX 프로그램 활용)

  • Kim, Dokyun;Choi, Jisoo;Oh, Hye-Ji;Chang, Kwang-Hyeon;Choi, Kwangsoon;Shin, Kyung-Hoon
    • Korean Journal of Ecology and Environment
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    • v.54 no.4
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    • pp.303-314
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    • 2021
  • To understand how to efficiently observe the biomass and community of phytoplankton, phytoplankton sampling was carried out from June to October 2019 at the Yeongju dam sediment control reservoir(YJ) and Bohyeonsan dam reservoir(BH1 and BH2). The results derived from microscopic observation, such as the conventional phytoplankton qualitative/quantitative analysis, and from the CHEMTAX method based on the pigments, were compared. The relative contribution of phytoplankton, calculated by the microscopy and CHEMTAX methods, showed a significant difference in all four classes: cryptophyta, chlorophyta, cyanobacteria, and diatoms. In addition, the correlation between the two observation methods was poor. This might be caused by methodological differences in microscopy that do not consider the varying cell sizes among phytoplankton species. In this study, by converting the cells into carbon, the slope between both carbon biomasses based on microscopy and CHEMTAX was improved close to the 1 : 1 line, and the y-intercept was closer to 0 for cryptophyta and diatoms. For cyanobacteria, the slope increased, the y-intercept decreased, and the plot approached 1 : 1 although the correlation coefficients were not improved in all classes. The present study suggests that application of CHEMTAX based on pigment analysis could be a possible approach to efficiently determine the relative carbon proportions of individual classes of phytoplankton community composition.