• Title/Summary/Keyword: Seasonal effect

Search Result 696, Processing Time 0.028 seconds

The Effect of Seeding Dates on Productivity and Botanical Composition in Oversown Hilly Pasture of mixed grass, Pyeongchang of South Korea (평창지역에서 겉뿌림 산지초지 조성시 목초 파종시기가 초지의 생산성과 식생에 미치는 영향)

  • Jung, Jeong Sung;Kim, Jong Geun;Kim, Hyeon Shup;Ji, Hee Jung;Choi, Ki Choon;Choi, Gi Jun;Choi, Boram;Oh, Seung Min;Kim, Won Ho
    • Journal of The Korean Society of Grassland and Forage Science
    • /
    • v.38 no.4
    • /
    • pp.217-223
    • /
    • 2018
  • This study was conducted to investigate the effect of seeding dates on grassland productivity and botanical composition in oversown hilly pasture located in Pyeongchang of South Korea. Four treatment groups were established based on the seeding dates of grass mixture: T1, August 13; T2, August 27; T3, September 10; and T4, September 24. Evaluation of seasonal changes in grass botanical composition revealed the highest ratios of grass in T1 and T2 (81-100% grass) and the lowest in T4 (46-90 % grass). In the plant length, the first harvest time was longer than other cutting times and last harvest time was the lowest. The total dry matter yield of grass was highest in T2 ($9,042kg\;ha^{-1}$) and T1 ($8,845kg\;ha^{-1}$) and lowest in T4 ($5,086kg\;ha^{-1}$). The findings of the present study suggest that seeding by late August provide the most desirable results for vegetation and grassland productivity in oversown hilly pasture, Pyeongchang of South Korea.

The Effect of COVID-19 on Pediatric Intussusception: A Retrospective Study of a Single Center in South Korea with 10-Year Experience (코로나바이러스감염증-2019 유행 후 소아 장중첩증의 변화: 단일기관 10년 의무 기록을 이용한 연구)

  • Yeo Jin Yoo;Bo-Kyung Je;Ga Young Choi;Jee Hyun Lee;Sunkyu Choi;Ji Young Lee
    • Journal of the Korean Society of Radiology
    • /
    • v.83 no.2
    • /
    • pp.304-316
    • /
    • 2022
  • Purpose To evaluate the effect of the emergence of coronavirus disease-19 (COVID-19) on pediatric intussusception. Materials and Methods Patients (< 18 years) who were diagnosed with intussusception and received enema reduction from 2011 to 2020 were included. We reviewed the demographics, yearly/monthly/seasonal incidence of intussusception, method and failure rate of enema reduction, recurrence rate of intussusception, surgical record, and pathologic report. Subsequently, we investigated the differences in mean age, failure rate of enema reduction, and recurrence rate of intussusception between the cases in 2020 and those in the period from 2011 to 2019. Results A total of 859 enema reductions were performed during the past decade, more in males and in the age < 1 year (mean age, 22.2 months). The yearly incidence was highest in 2014 and lowest in 2020, and the monthly incidence was highest on December and September. The cases in 2020 (n = 27) had a lower mean age (18.1 months vs. 22.8 months), higher failure rate of enema reduction (7.4% vs. 2.4%), and higher recurrence rate of intussusception (14.8% vs 7.3%) compared with those that occurred between 2011 and 2019 (n = 832). However, these results did not show statistical significance (p = 0.07, p = 0.15, p = 0.14, respectively). Conclusion With the emergence of COVID-19, the number of enema reductions was remarkably decreased with a lower mean age, higher failure rate, and higher recurrence rate.

Effects of Nutrients and N/P Ratio Stoichiometry on Phytoplankton Growth in an Eutrophic Reservoir (부영양 저수지에서 식물플랑크톤 성장에 대한 제한영양염과 질소/인 비의 영향)

  • Kim, Ho-Sub;Hwang, Soon-Jin
    • Korean Journal of Ecology and Environment
    • /
    • v.37 no.1 s.106
    • /
    • pp.36-46
    • /
    • 2004
  • We evaluated the effect of limiting nutrients and N/P ratio on the growth of phytoplankton in a small eutrophic reservoir from November 2002 to December 2003. Nutrient limitation was investigated seasonally using nutrient enrichment bioassay (NEB). DIN/DTP and TN/TP ratio (by weight) of the reservoir during the study period ranged 17${\sim}$187 and 13${\sim}$60, respectively. Most of nitrogen in the reservoir account for $NO_3$-N, but sharp increase of ammonia was evident during the spring season. Seasonal variation of dissolved inorganic phosphorus concentration was relatively small. DTP ranged 26.5${\sim}$10.1 ${\mu}g\;P\;L^{-1}$, and the highest and lowest concentration was observed in August and December, respectively. Chlorophyll a concentration ranged 28.8${\sim}$109.7 ${\mu}g\;L^{-1}$, and its temporal variation was similar to that of cell density of phytoplankton. Dominant phytoplankton species were Bacillariphyceae (Melosira varians) and Chlorophyceae (Dictyosphaerium puchellum) in Spring (March${\sim}$April). Cyanophyceae, such as Osillatoria spp., Microcystis spp., Aphanizomenon sp. dominated from May to the freezing time. TN/TP ratio ranged from 46 to 13 (Avg. 27${\pm}$6) from June to December when cyanobacteria (Microcystis spp.) dominated. p limitation for algal growth measured in all NEB experiments (17cases), while N limitation occurred in 8 out of 17 cases. The growth rates of phytoplankton slightly increased with decreasing of DIN/DTP ratio. Evident increase was observed in the N/P ratio of > 30, and it was sustained with DTP increase until 50 ${\mu}g\;P\;L^{-1}$. Under the same N/P mass ratio with the different N concentrations (0.07, 0.7and 3.5 mg N $L^{-1}$), Microcystis spp. showed the highest growth rate in the N/P ratio of< 1 with nitrogen concentration of 3.5 mg N $L^{-1}$). The responses of phytoplankton growth to phosphate addition were clearly greater with increase of N concentration. These results indicate that the higher nitrogen concentration in the water likely induce the stronger P-limitation on the phytoplankton growth, while nitrogen deficiency is not likely the case of nutrient limitation.

Construction and Evaluation of Cohort Based Model for Predicting Population Dynamics of Riptortus pedestris (Fabricicus) (Hemiptera: Alydidae) Using DYMEX (상용소프트웨어(DYMEX)를 이용한 톱다리개미허리노린재(Riptortus pedestris) 밀도 변동 양상 예측 모델 구축 및 평가)

  • Park, Chang-Gyu;Yum, Ki-Hong;Lee, Sang-Ku;Lee, Sang-Guei
    • Korean journal of applied entomology
    • /
    • v.54 no.2
    • /
    • pp.73-81
    • /
    • 2015
  • A Cohort based model for temperature-dependent population dynacmics of Riptortus pedestris was constructed by using a commercial software (DYMEX) and seasonal occurrence along with pesticide treatments effect was simulated and validated with pheromone trap data. Ten modules of DYMEX software were used to construct the model and Lifecycle module was consisted of seven developmental stages (egg, 1 - 5 nymphal instars, and adult) of R. pedestirs. Simulated peaks of adult populations occurred three or four times after the peak of overwintered populations which was similar to those observed from pheromone trap catch. Estimated dates for the second peak were quite similar (1-2 day difference) with those observed with pheromone trap. However, the estimated dates for the first population peak were 9-16 days later than the observed dates by pheromone trap and the estimated dates for the last peak were 17-23 days earlier than the observed dates. When insecticide treatments were included in the simulation, the biggest decrease in R. pedestris adult density occurred when insecticide was applied on July 1 for the first peak population: the estimated adult density of the second peak was 3% of untreated population density. When insecticide was assumed to be applied on August 30 for the second peak population, the estimated adult density of the following generation was about 25% of untreated population and the peak density of the following generation reached about two weeks later than untreated population. These results can be used for the efficient management strategies for the populations of R. pedestris.

A Study on Marketing of Cultured Laver Products (양식해태의 유통에 관한 조사 연구)

  • 유충열
    • The Journal of Fisheries Business Administration
    • /
    • v.4 no.1_2
    • /
    • pp.19-57
    • /
    • 1973
  • Laver io one of the most necessary and seasonal items in Korean food from oldtimes. Laver is lagely eaten in dried form, and its supply depends entirely upon culture weeds. The history of laver culture in Korea about sixty or seventy years is older than in Japan. Significance of laver culture is divided into two aspects, one is food supply in the nation, and the other is export to other countries. Houses engaged in laver culture are about foully thousands, and laver production in 1972 is estimated as 1, 3 bitten sheets. (1 sheet is a dried laver of 20 cm sq, in the shape of paper) Especcially meaning of layer production is the concentration of labour input, and systematic management of labour. From around 1920, the method of laver culture was introduced by Japanese Imperialism for mono culture in shallow seas, and mass products of laver is provided to Japan market, DOMESTIC MARKET Fundamental consume function calculates at below, $D_{(68_71)}$=16354 $Y^{0.471}$ $P^{-1.0662}$ where D is total layer demand, Y income variable, P price variable. It means income elasticity is 476. in the whole country, and price elasticity is 1, 07. But generally income elasticity is higher in urban area than in rural area, as shown at 1, 3 in Seoul city. Expence of laver in house expenditure is mutually correlated with another expence, See Table 12 about the relative function. See Table 14 and 16 about the relation between the gathering and the changes of price in auction, wholesale and retail price support system is for two effects, one of which is constraint of the upper price, the other is rise of the lower price. Before the system control, the equation in three year average calculated as below, $Y_{b}$ =18, 907.7455+15435.9364 t (r=0.89) where the origin t=0 is the November and the units are month. Post the system control, $Y_{p}$ =30, 047.9636+1, 631.1721t (r=0.97) therefore, this system has an effect only on the rise of lower price, Average annual margins of laver products at four market levels according to the consumer spent is below. EXPORTING MARKET Japanese demand function of laver products is, Log D=5, 289+1, 108 Log Y-1, 395 Log P (r=0.987) where D is Japanese laver demand, Y income variable, P price variable. according to which income elasticity is 1. 1 and price elasticity is 1.4. Laver production in 1970 tile highest record till then, is estimated as six billion sheets. But the recent improvement of laver culture techniques, the production of seeds and freezing storage of seeds has been stabilized. Futher new culture farms have been developed by means of break- water fences or by floating culture method. These improvements have been backed up with increased demand of laver products. Import quantity and price of Korean laver products are restrained by three organizations, that is producer, distributor and consumer. This relationship calculated by regression equation shows that import is influenced only producer organization, at the sacrifice of consumer profit. For increase to export of laver products, we urgently require to open foreign trade of laver products for Japanese consumer, .and Japan has political responsibility to solve Korean laver structure. But with long run timeseries, as regards Japanese production and import quantity, importing function shows increasing trend as below, 250 million sheets <3, 947.1674+0.005 $L_{g}$ >) 600 million sheets where $L_{q}$ is relative production quantity of laver in Japan. (unit; 100 thousand sheets) Our Export effort should be put on the highly processed products whithin the restraind quote.ote.

  • PDF

Comparisons of 1-Hour-Averaged Surface Temperatures from High-Resolution Reanalysis Data and Surface Observations (고해상도 재분석자료와 관측소 1시간 평균 지상 온도 비교)

  • Song, Hyunggyu;Youn, Daeok
    • Journal of the Korean earth science society
    • /
    • v.41 no.2
    • /
    • pp.95-110
    • /
    • 2020
  • Comparisons between two different surface temperatures from high-resolution ECMWF ReAnalysis 5 (ERA5) and Automated Synoptic Observing System (ASOS) observations were performed to investigate the reliability of the new reanalysis data over South Korea. As ERA5 has been recently produced and provided to the public, it will be highly used in various research fields. The analysis period in this study is limited to 1999-2018 because regularly recorded hourly data have been provided for 61 ASOS stations since 1999. Topographic characteristics of the 61 ASOS locations are classified as inland, coastal, and mountain based on Digital Elevation Model (DEM) data. The spatial distributions of whole period time-averaged temperatures for ASOS and ERA5 were similar without significant differences in their values. Scatter plots between ASOS and ERA5 for three different periods of yearlong, summer, and winter confirmed the characteristics of seasonal variability, also shown in the time-series of monthly error probability density functions (PDFs). Statistical indices NMB, RMSE, R, and IOA were adopted to quantify the temperature differences, which showed no significant differences in all indices, as R and IOA were all close to 0.99. In particular, the daily mean temperature differences based on 1-hour-averaged temperature had a smaller error than the classical daily mean temperature differences, showing a higher correlation between the two data. To check if the complex topography inside one ERA5 grid cell is related to the temperature differences, the kurtosis and skewness values of 90-m DEM PDFs in a ERA5 grid cell were compared to the one-year period amplitude among those of the power spectrum in the time-series of monthly temperature error PDFs at each station, showing positive correlations. The results account for the topographic effect as one of the largest possible drivers of the difference between ASOS and ERA5.

A Study of Bleaching Phenomenon of Otter (Lutra lutra) Spraints in Relation to Weather Conditions and Characteristics of Sprainting Sites (기상조건과 배설지 특성에 따른 수달(Lutra lutra) 분변의 표백현상에 관한 연구)

  • Noh, Eun-Young;Han, Sung-Yong;Yoo, Jeong-Chil
    • Journal of Wetlands Research
    • /
    • v.17 no.1
    • /
    • pp.1-10
    • /
    • 2015
  • The bleaching phenomenon of otter spraints is indicates that the age of spraints (fresh or old spraints). As previous studies on the old otter faeces (spraint) have focused only on the external changes of spraints, it has been difficult to explain the difference of the decomposition rates among old spraints. We hypothesized that the micrometeorology difference caused by various characteristics of sprainting sites such as porosity and consistency of soil could affect the extent of the decomposition rate, the solar bleaching phenomenon of spraints used as a measure of the patterns of old spraints. Sprainting sites were classified into four types (Clay, Sand, Rock and Concrete spot) and each type was divided into two groups according to the sunlight condition (Sunny site and Shady site) to measure the effect of solar radiation. Micrometeorology of the sites were evaluated by measuring temperatures and humidities of the sites during the whole season. The variations in micrometeorology of the sunny sites according to the sprainting site types were examined with correlation analyses between the factors of micrometeorology. The analyses on the bleaching phenomenon of the spraints by micrometeorology showed that the highest rate of bleaching was found at the 'Rock spot' and 'Concrete spot' of the sunny site and especially in summer, the highest rate of bleaching ($63.4{\pm}7.6%$) was found at the 'Clay spot' of the sunny sites. The lowest rate of bleaching was found at the 'Sand spot' of the sunny sites. The above findings show that the difference in bleaching rates among sprainting sites was due to the seasonal or sunny condition. In addition, we found that the differences in thermal conductivity among sprainting site characteristics have resulted in different sprainting site temperature which have affected the rate of bleaching of spraints. In conclusion, this study suggests that studies of otters on their population size and home ranges using spraints as an indirect sign, should consider the effects of sprainting site characteristics and weather conditions.

Effect of Seasonal Distribution Temperature on Storability of Modified Atmosphere Packaged Baby Leaf Beet (계절별 수송 온도가 MA 포장한 어린잎 비트의 저장성에 미치는 영향)

  • Choi, In-Lee;Han, Su Jung;Kim, Ju Young;Ko, Young-Wook;Kim, Yongduk;Hwang, Myung-Keun;Yu, Wanggun;Kang, Ho-Min
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
    • /
    • v.24 no.2
    • /
    • pp.85-89
    • /
    • 2018
  • The effects of distribution temperature due to season all changes on quality and storability of baby leaf beet (Beta vulgaris L.) was examined in modified atmosphere (MA) packages. The beet leaf had been harvested at the 10 cm leaf length stage and packaged with an oxygen transmission rate (OTR) film of $1,300cc{\cdot}m^{-2}{\cdot}day^{-1}{\cdot}atm^{-1}$ and then held at 4 different distribution temperatures which were $-2^{\circ}C$, $4^{\circ}C$, $20^{\circ}C$, or $30^{\circ}C$ for 5 hrs and then stored for 18 days at $8^{\circ}C$. The loss of fresh weight of packged baby leaf beet was lowest at the $4^{\circ}C$ treatment, and below 0.6% in all distribution temperature treatments. The atmosphere composition in packages did not show any significant differences among treatments. The oxygen conc. was the highest at 18.0% after the $4^{\circ}C$ treatment, carbon dioxide conc. showed the maximum value of 4% at the $30^{\circ}C$ and $-2^{\circ}C$ treatments, and ethylene conc. was highest at the $10^{\circ}C$ treatment after 10 days in storage. The hardness was the highest at the $4^{\circ}C$ treatment on the final storage day. The $4^{\circ}C$ treatment showed the highest visual quality and the lowest off-odor and aerobic plate count. Therefore, it is necessary to establish a low-temperature distribution system which is controlled under $4^{\circ}C$, because the baby leaf beet's storability and microbial growth are effected even during a short time of 5 hrs during the distribution process.

Analysis of the Status of Light Pollution and its Potential Effect on Ecosystem of the Deogyusan National Park (덕유산국립공원 빛공해 현황 및 빛공해가 공원 생태계에 미치는 잠재적 영향 분석)

  • Sung, Chan Yong;Kim, Young-Jae
    • Korean Journal of Environment and Ecology
    • /
    • v.34 no.1
    • /
    • pp.63-71
    • /
    • 2020
  • This study characterized the spatial and seasonal patterns of light pollution in the Deogyusan National Park and examined the potential effects of light pollution on ecosystems in the park using light intensities derived from VIIRS (Visible Infrared Imaging Radiometer Suite) DNB (Day and Night Band) nightlight images collected in January and August 2018. Results showed that the Muju Deogyusan resort had the greatest light intensity than other sources of light pollution in the park, and light intensity of the resort was much higher in January than in August, suggesting that artificial lights in ski slopes and facilities were the major source of light pollution in the park. An analysis of an urban-natural light pollution gradient along a neighboring urban area through the inside of the park indicated that light radiated from a light pollution source permeated for up to 1km into the adjacent area and contaminated the edge area of the park. Of the legally protected species whose distributions were reported in literature, four mammals (Martes flavigula, Mustela nivalis, Prionailurus bengalensis, Pteromys volans aluco), two birds (Falco subbuteo, Falco tinnunculus), and nine amphibians and reptiles (Onychodactylus koreanus, Hynobius leechii, Karsenia koreana, Rana dybowskii, Rana huanrenensis, Elaphe dione, Rhabdophis tigrinus, Gloydius ussuriensis, Gloydius saxatilis) inhabited light-polluted areas. Of those species inhabiting light-polluted areas, nocturnal species, such as Prionailurus bengalensis and Pteromys volans aluco, in particular, were vulnerable to light pollution. These results implied that protecting ecosystems from light pollution in national parks requires managing nighttime light in the parks and surrounding areas and making a plan to manage nighttime light pollution by taking into account ecological characteristics of wild animals in the parks.

Effect of Light-Quality Control on Growth of Ledebouriella seseloides Grown in Plant Factory of an Artificial Light Type (인공광 식물공장내 광질 제어가 방풍나물 생장에 미치는 영향)

  • Heo, Jeong-Wook;Kim, Dong-Eok;Han, Kil-Su;Kim, Sook-Jong
    • Korean Journal of Environmental Agriculture
    • /
    • v.32 no.3
    • /
    • pp.193-200
    • /
    • 2013
  • BACKGROUND: Plant factory system of an artificial light type using Light-Emitting Diodes (LEDs), fluorescent light, or metal halide lamp instead of sun light is an ultimated method for plant production without any pesticides regardless of seasonal changes. The plant factory is also completely isolated from outside environmental conditions such as a light, temperature, or humidity compared to conventional greenhouse. Light-environment control such as a quality or quantity in the plant factory system is essential for improving the growth and development of plant species. However, there was little report that the effects of various light qualities provided by LEDs on Ledebouriella seseloides growth under the plant factory system. METHODS AND RESULTS: Ledebouriella seseloides seedlings transplanted at urethane sponge were grown in the plant factory system of a horizontal type with LED artificial lights for 90 days. Yamazaki solution for hydroponic culture of the seedlings was regularly irrigated by the deep flow technique (DFT) system on the culture gutters. Electrical Conductivity (EC) and pH of the solution was recorded at 1.4 ds/m and 5.8 in average, respectively during the experimental period. Number of unfolded leaves, leaf length, shoot fresh and dry weight of the seedlings were three times measured in every 30 days after beginning of the experiment. Blue LEDs, red LEDs, and fluorescent lights inside the plant factory were used as light sources. Conventional fluorescent lamps were considered as a control. In all the treatment, light intensity was maintained at $100{\mu}mol/m^2/s$ on the culture bed. Fresh weight of the seedlings was 3.7 times greater in the treatment with the mixture radiation of fluorescent light and blue+red LEDs (1:3 in energy ratio; Treatment FLBR13) than in fluorescent light treatment (Treatment FL). In FLBR13 treatment, dry weight per seedling was two times greater than in FL or BR11 treatment of blue+red LEDs (1:3 in energy ratio; Treatment BR11) during the culture period. Increasing in number of unfolded leaves was also significantly affected by the FLBR13 treatment comparing with BR11 treatment. CONCLUSION(S): Hydroponic culture of Ledebouriella seseloides seedlings was successfully achieved in the plant factory system with mixture lights of blue, red LEDs and fluorescent lights. Shoot growth of the seedlings was significantly promoted by the FLBR13 with the mixture radiation of fluorescent light, blue, and red LEDs under 1:3 mixture ratio of blue and red LEDs during the experimental period compared to conventional light conditions.