• Title/Summary/Keyword: The Characteristics of Change

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Characteristics of Pesticide Runoff and Persistence on Agricultural Watersheds in Korea (영농지역에서 작물재배 형태에 따른 농약의 잔류성과 유출특성)

  • Park, Byung-Jun;Kwon, Oh-Kyung;Kim, Jin-Kyoung;Kim, Jin-Bea;Kim, Jin-Ho;Yoon, Soon-Kang;Shim, Jae-Han;Hong, Moo-Gi
    • Korean Journal of Environmental Agriculture
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    • v.28 no.2
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    • pp.194-201
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    • 2009
  • To evaluate the exposure of non-point source pesticide pollution in agricultural watershed and to investigate pesticide distribution and runoff from agricultural land, paddy field, upland and orchard, this experiment was carry out during crop growing seasons. The pesticide were detected twenty pesticides fungicide 4, insecticide 10, herbicide 6) in water of Neungchon agricultural watershed and detection concentrations were range 0.008${\sim}$7.59 ppb. Most of the detection pesticides were using pesticides to rice paddy fields to control fungi, insects, weeds. During the crop cultivation, the pesticide were detected total thirty pesticides by pepper field soil 6, orchard soil 4, sesame field soil 3 and rice paddy field soil 5, and pesticide concentrations were range 0.001${\sim}$0.109 ppm. Especially the herbicides were detected mainly in May and June in the stream water. The pesticide were detected thirty pesticides by fungicide 2, insecticide 6, herbicide 5 in water of Jungam Koseong agricultural watershed and detection concentrations were range 0.01${\sim}$7.21 ppb. In regard to the detected pesticides, the concentration of individual pesticides measured in surface water of the study areas never exceeded guidelines for agriculture chemicals concerning water quality-effluent from paddy fields in Japan (Katayama, 2003). Runoff rate of pesticides was range 0.07${\sim}$3.06 % from Kongju agricultural land to watershed after applied pesticides.

Methylene Blue Photodegradation Properties of Anatase/brookite Hybrid TiO2 Photocatalyst Prepared with Different Acid Catalysts (산 촉매에 따른 아나타제/브루카이트 혼성형 TiO2 광촉매의 메틸렌블루 광분해특성)

  • Yun, Seok-Min;Kim, Jinhoon;Jeong, Euigyung;Im, Ji Sun;Lee, Young-Seak
    • Applied Chemistry for Engineering
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    • v.22 no.1
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    • pp.21-25
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    • 2011
  • In this study, anatase/brookite hybrid $TiO_2$ was prepared using different acid catalysts and microwave to improve photodegradation of organic pollutants. The methylene blue photodegradation properties of the prepared photocatalysts with different particle/crystal size and brookite fractions were investigated. Surface characteristics and particle sizes of anatase/brookite hybrid $TiO_2$ were evaluated using scanning electron microscopy (SEM) and laser diffraction particle size analyzer, respectively and crystal structures were investigated with X-ray diffraction (XRD). Methylene blue photodegradation properties were evaluated with UV-vis spectrophotometer. Anatase and anatase/brookite hybrid $TiO_2$ had less than 500 nm size of clusters and the average particle size of $6.66{\sim}6.85{\mu}m$, suggesting that types of acid catalysts did not affect the size. XRD of the prepared $TiO_2$ showed that the photocatalysts had anatase/brookite hybrid crystal structure and applying microwave did not change their crystal structure. Photodegradation of methylene blue with the prepared photocatalyst did not increased proportionally to the fraction of brookite and the crystal size and decreased when brookite fraction and the crystal size increased further. Anatase/brookite hybrid $TiO_2$ with brookite fraction of 9.4% and crystal size of 4.53 nm shows the best photodegradation activity of methylene blue.

Floristic Study of Sangwangsan Mt. and Its Adjacent Areas(Wando-gun) (완도 상왕산 일대의 식물상 연구)

  • Gwang-Il Kim;Chan-jin Oh;Sun-jin Lee;Soon-Ho Shin;Kyoung-Pae Yun
    • Korean Journal of Environment and Ecology
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    • v.37 no.2
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    • pp.100-139
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    • 2023
  • This study was intended to identify the distribution and characteristics of plants such as native plants, rare plants, and endemic plants through a flora survey in Sangwangsan Mt. (644m), Wando-gun, Jeollanam-do, a group habitat of warm temperate forests in Korea, and use the data for the conservation of plant species diversity and the study of climate and distribution changes in warm-temperate forests. A total of 32 field surveys were conducted from 2018 to 2022. The survey identified 785 taxa, including 8 forms, 53 varieties, 16 subspecies, 708 species, 473 genera, and 132 families. The endangered wild plants designated by the Ministry of Environment included 6 taxa: Woodwardia japonica, Metanarthecium luteoviride, Bulbophyllum inconspicuum, Dendrobium moniliforme, Pelatantheria scolopendrifolia, and Cymbidium macrorhizon. Rare plants designated by the Korea Forest Service were identified as 26 taxa. The red list designated by the Korea National Arboretum was identified as 7 taxa, the red list designated by the Ministry of Environment was identified as 29 taxa, and endemic plants in Korea were identified as 17 taxa. Floristic target species in Korea were identified as 200 taxa, specifically 6 taxa of grade V, 13 taxa of grade IV, 73 taxa of grade III, 29 taxa of grade II, and 79 taxa of grade I. Naturalized plants were identified as 73 taxa, and invasive alien plants were identified as 6 taxa. Target plants adaptable to climate change in Korea were identified as 55 taxa, specifically 8 taxa of endemic plants, 46 taxa of southern plants, and 1 taxon of northern plants.

The Fermentative Characteristics of Cheonggukjang Prepared by Starter Culture of Bacillus spp. with Fibrinolytic Activity (혈전용해활성이 우수한 Bacillus spp. 스타터를 이용한 청국장의 발효특성)

  • Hwang, Jong-Hyun
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.39 no.12
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    • pp.1832-1838
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    • 2010
  • The objective of this study was to improve the flavor of Cheonggukjang prepared by the culture optimization of starter with the fibrinolytic activity. After 25 strains isolated from the commercial Cheonggukjang and Doenjang in different regions were compared, 7 Bacillus strains with proteolytic and slime-producing activities were selected. When the fibrin plate method for fibrinolytic activity was applied, CJJN-4 and 5 showed the higher activity in tripticase soy broth (TSB). All Cheonggukjang prepared with CJJN-4 and 5 also had the fibrinolytic activity, regardless of culture temperature or time. Especially, Cheonggukjang prepared at $40^{\circ}C$ showed higher activity than $45^{\circ}C$, and Cheonggukjang prepared with CJJN-4 for 48 hr at $40^{\circ}C$ showed the highest fibrinolytic activity. Although there was no significant difference in pH of Cheonggukjang prepared with CJJN-4 or 5 during 72 hr at $40^{\circ}C$, Cheonggukjang prepared with CJJN-4 at $45^{\circ}C$ had lower pH until 60 hr than $40^{\circ}C$ or CJJN-5. The total amino type nitrogen contents of Cheonggukjang were 1,139.6 (CJJN-4) and 1,027.6 mg% (CJJN-5) for 72 hr at $40^{\circ}C$, and their producing rates were also higher at $40^{\circ}C$ fermentation than $45^{\circ}C$. Meanwhile, the contents of ammonia type nitrogen induced unpleasant flavor were lower in Cheonggukjang with CJJN-4 and 5 at $40^{\circ}C$ than CJJN-5 at $45^{\circ}C$. Therefore, Cheonggukjang fermented with CJJN-4 starter at $40^{\circ}C$ had the improved flavor, such as change of amino or ammonia type nitrogen production, and higher fibrinolytic activity.

Estimation of Chlorophyll-a Concentration in Nakdong River Using Machine Learning-Based Satellite Data and Water Quality, Hydrological, and Meteorological Factors (머신러닝 기반 위성영상과 수질·수문·기상 인자를 활용한 낙동강의 Chlorophyll-a 농도 추정)

  • Soryeon Park;Sanghun Son;Jaegu Bae;Doi Lee;Dongju Seo;Jinsoo Kim
    • Korean Journal of Remote Sensing
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    • v.39 no.5_1
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    • pp.655-667
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    • 2023
  • Algal bloom outbreaks are frequently reported around the world, and serious water pollution problems arise every year in Korea. It is necessary to protect the aquatic ecosystem through continuous management and rapid response. Many studies using satellite images are being conducted to estimate the concentration of chlorophyll-a (Chl-a), an indicator of algal bloom occurrence. However, machine learning models have recently been used because it is difficult to accurately calculate Chl-a due to the spectral characteristics and atmospheric correction errors that change depending on the water system. It is necessary to consider the factors affecting algal bloom as well as the satellite spectral index. Therefore, this study constructed a dataset by considering water quality, hydrological and meteorological factors, and sentinel-2 images in combination. Representative ensemble models random forest and extreme gradient boosting (XGBoost) were used to predict the concentration of Chl-a in eight weirs located on the Nakdong river over the past five years. R-squared score (R2), root mean square errors (RMSE), and mean absolute errors (MAE) were used as model evaluation indicators, and it was confirmed that R2 of XGBoost was 0.80, RMSE was 6.612, and MAE was 4.457. Shapley additive expansion analysis showed that water quality factors, suspended solids, biochemical oxygen demand, dissolved oxygen, and the band ratio using red edge bands were of high importance in both models. Various input data were confirmed to help improve model performance, and it seems that it can be applied to domestic and international algal bloom detection.

The 2009-based detailed distribution pattern and area of Phragmites communis-dominant and Suaeda japonica-dominant communities on the Suncheon-bay and Beolgyo estuarine wetlands (순천만과 벌교 하구 연안습지의 2009년 기준 갈대 및 칠면초 우세 군집 분포양상과 면적 제시)

  • Hong, Seok Hwi;Chun, Seung Soo;Eom, Jin Ah
    • Journal of Wetlands Research
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    • v.17 no.1
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    • pp.26-37
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    • 2015
  • Halophyte distribution pattern and area in the Suncheon-bay and Beolgyo estuary coastal wetlands were analyzed using KOMPSAT-2 landsat images were taken in 2008 and 2009, and field investigations were fulfilled for confirming the precise boundaries of individual halophyte areas. The salt-marsh vegetation in those areas can be classified mainly into two dominant communities: Suaeda japonica-dominant and Phragmites communis-dominant communities. In order to identify sedimentary characteristics, tidal-flat surface leveling and sedimentary facies analysis had been conducted. The sedimentary facies of marsh area are mostly silty clayey and clay facies with a little seasonal change and its slope is very gentle (0.0007~0.002 in gradient). Phragmites communis and Suaeda japonica communities were distributed in the mud-flat zone between 0.7 m and 1.8 m higher than MSL (mean sea level): zone of 1.1~1.8 m in the former and zone of 0.7~1.3 m in the latter. In the Suncheon-bay estuarine wetland, on the basis of 2009 distribution, Phragmites communis-dominant and Suaeda japonica-dominant communities are about $0.79km^2$ and $0.22km^2$ in distribution area, respectively. On the other hand, Bulgyo estuarine marsh shows that the distribution areas of Phragmites communis-dominant and Suaeda japonica-dominant communities are about $0.31km^2$ and 0.031km2 in distribution area, respectively. Individual 105 and 60 dominant community areas and their distribution patterns can be well defined and indicated in the Suncheon-bay and Bulgyo estuarine marshes, respectively. The distribution pattern and area of hylophyte communities analyzed in this study based on 2008/2009 satellite images would be valuable as a base of future monitoring of salt-marsh related studies in the study area which is the most important salt-marsh research site in Korea.

Effects of Temperature on the Development and Reproduction of Phaedon brassicae Baly (Coleoptera: Chrysomelidae) (좁은가슴잎벌레의 발육과 생식에 미치는 온도의 영향)

  • Jeong Joon Ahn;Kwang Ho Kim;Hong Hyun Park;Gwan Seok Lee;Jeong Hwan Kim;In-Hong Jeong
    • Korean journal of applied entomology
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    • v.62 no.4
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    • pp.315-323
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    • 2023
  • The brassica leaf beetle, Phaedon brassicae Baly (Coleoptera: Chrysomelidae), is one of the important pests infesting cruciferous vegetables. In order to understand the biological characteristics of the insect, we investigated the effects of temperature on development of each life stage, adult longevity and fecundity of P. brassicae at four constant temperatures of 15, 20, 25 and 27.5℃ for immature life stage and five constant different temperatures of 10, 15, 20, 25 and 27.5℃ for adult stage. Eggs and larvae successfully developed next life stage at temperature tested. The development period of egg, larva, and pupa decreased as temperature increased. Lower developmental threshold (LDT) and thermal constant (K) were calculated using linear regression as 8.7℃ and 344.73DD, respectively. Lower and higher threshold temperature (TL and TH) from egg to adult emergence were estimated by Briere function as 5.3℃ and 40.4℃, respectively. Adults produced eggs at the temperature range between 10℃ and 27.5℃, and showed an estimated maximum number, ca. 627.5 eggs at 21.7℃. Adult oviposition models including aging rate, age-specific survival rate, age-specific cumulative oviposition, and temperature-dependent fecundity were constructed. Temperature-dependent development models and adult oviposition models would be useful components to understand the population dynamics of P. brassicae and to establish the strategy of integrated pest management in cruciferous crops.

Electrochemical Characteristics of Cu3Si as Negative Electrode for Lithium Secondary Batteries at Elevated Temperatures (리튬 이차전지 음극용 Cu3Si의 고온에서의 전기화학적 특성)

  • Kwon, Ji-Y.;Ryu, Ji-Heon;Kim, Jun-Ho;Chae, Oh-B.;Oh, Seung-M.
    • Journal of the Korean Electrochemical Society
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    • v.13 no.2
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    • pp.116-122
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    • 2010
  • A $Cu_3Si$ film electrode is obtained by Si deposition on a Cu foil using DC magnetron sputtering, which is followed by annealing at $800^{\circ}C$ for 10 h. The Si component in $Cu_3Si$ is inactive for lithiation at ambient temperature. The linear sweep thermammetry (LSTA) and galvano-static charge/discharge cycling, however, consistently illustrate that $Cu_3Si$ becomes active for the conversion-type lithiation reaction at elevated temperatures (> $85^{\circ}C$). The $Cu_3Si$ electrode that is short-circuited with Li metal for one week is converted to a mixture of $Li_{21}Si_5$ and metallic Cu, implying that the Li-Si alloy phase generated at 0.0 V (vs. Li/$Li^+$) at the quasi-equilibrium condition is the most Li-rich $Li_{21}Si_5$. However, the lithiation is not extended to this phase in the constant-current charging (transient or dynamic condition). Upon de-lithiation, the metallic Cu and Si react to be restored back to $Cu_3Si$. The $Cu_3Si$ electrode shows a better cycle performance than an amorphous Si electrode at $120^{\circ}C$, which can be ascribed to the favorable roles provided by the Cu component in $Cu_3Si$. The inactive element (Cu) plays as a buffer against the volume change of Si component, which can minimize the electrode failure by suppressing the detachment of Si from the Cu substrate.

Quality Changes of 'Baumkuchen' Cake with Modified Atmosphere Packaging during Storage (변형기체포장 처리에 따른 '바움쿠헨' 케이크의 저장 중 품질 특성 변화)

  • Myungho Lee;Minhwi Kim;Youn Suk Lee
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.29 no.2
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    • pp.87-94
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    • 2023
  • Fresh bakery products are widely consumed worldwide and therefore particular requirements for their quality characteristics have been established. The shelf life of bakery products is mainly subjected to microbial spoilage and staling. This study investigated the optimum conditions of modified atmosphere packaging (MAP) application to extend the shelf life of the bakery products. The gas conditions of the headspace in 'Baumkuchen' cake were 0, 30, 70, and 100% CO2 concentrations and stored at 30℃ for 5 days. The bakery samples were evaluated weight loss, hardness, color change, pH and total aerobic bacteria, yeast and molds count throughout the storage period. Values of the weight loss and hardness were increased over the storage period, meanwhile pH was significantly decreased. However, no significant color changes were observed during storage. It was also found no significant difference between the different gas treatments. Total aerobic bacteria count of the stored samples after day 5 was increased by 6.94 log CFU/g in the air filled package, compared to 6.20 log CFU/g in the 100% CO2 filled package and 6.02 log CFU/g in the 70% CO2 filled package. Yeast and molds count were 3.65 log CFU/g in air filled package, 2.66 log CFU/g in 100% CO2 filled package, 2.64 log CFU/g in 70% CO2 filled package, 2.86 log CFU/g in 30% CO2 filled package and 3.31 log CFU/g in 100% N2 filled package on day 2. In conclusion, it was shown that 70% and 100% CO2 treatments in the package were effective to reduce microbial growth.

Seasonal phytoplankton dynamics in oligotriphic offshore water of Dokdo, 2018 (2018년 독도 주변 빈영양 수괴에서 계절별 식물플랑크톤 동태)

  • Lee, Minji;Kim, Yun-Bae;Kang, Jung Hoon;Park, Chan Hong;Baek, Seung Ho
    • Korean Journal of Environmental Biology
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    • v.37 no.1
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    • pp.19-30
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    • 2019
  • To investigate the characteristics of seasonal environment and phytoplankton community structure in the coastal area of Dokdo, a survey of Dokdo around waters was conducted during the four seasons. Phytoplankton of 4 phylum 72 species in four seasons were collected in Dokdo around water. The seasonal mean abundance of phytoplankton were $3.32{\times}10^4cells\;L^{-1}$ in winter, $1.04{\times}10^4cells\;L^{-1}$ in spring, $0.28{\times}10^4cells\;L^{-1}$ in summer, and $4.86{\times}10^4cells\;L^{-1}$ in autumn in Dokdo around water. During winter, the diatoms Chaetoceros spp. had dominated. During spring, when the nutrients in the euphotic layer were depleted, the nano-flagellates and Cryptomonas appeared at surface layer. In summer, the abundance of phytoplankton was relatively low, which lead to occurrence of diatoms such as genus of Chaetoceros, Rhizosolenia, and Skeletonema. In autumn, Pseudo-nitzschia spp. was the most dominant species and tropical species such as Amphisolenia sp. and Ornithocercus magnificus were observed, implying that they may have introduced within warm water current such as Kurosiwo Current. Therefore, although natural phytoplankton communities in the vicinity water of Dokdo are mainly influenced by Tsushima Warm Current branched Kurosiwo Current, their population dynamics was affected on the spatio-temporal change of physicochemical factors by short-term wind events, namely "island effect". Long-term survey research is needed to facilitate food-web response in marine ecosystem associated with phytoplankton biomass and physicochemical factors including the warm water current in oligotrophic offshore water of Dokdo, which may have significant role for sustainable use of Dokdo.