• Journal of Ecology and Environment
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• v.44 no.1
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• pp.54-61
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• 2020

Background: Most fish undergo prey switch from juvenile to adult. It is thought that slightly different feeding habits occur among adult fishes due to growth, spawning, habitat change, and so on. Therefore, the diet of the John Dory Zeus faber (≥ 24 cm TL) was studied in the coastal waters of Korea by analysis of stomach contents, with comparison by season and size class of diet composition and prey diversity. Monthly samples were taken from February 2017 to January 2018. Results: The results showed that the John Dory was a piscivorous predator, and pisces had occupied 82.3% of IRI%. Trichiurus lepturus and Trachurus japonicus were important preys in all size classes and seasons. Diet composition differed among the size classes and seasons (Chi-square test, P < 0.05). As body size of Z. faber increased, the occurrence of benthic fish (Glyptocephalus stelleri) tended to increase. The seasonal prey composition also changed depending on the abundant species of each season. Conclusions: Z. faber is a piscivorous predator. The consumption habits of Z. faber appear to different results by their size and seasons. This study suggests that Z. faber could be considered an opportunistic predator.

• Journal of Forest and Environmental Science
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• v.30 no.3
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• pp.277-284
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• 2014

Status of Arbuscular Mycorrhizal (AM) colonization in seven tree species (Albizia saman, Acacia auriculiformis A. Cunn. ex Benth., Albizia lebbeck, Chickrassia tabularis A. Juss., Eucalyptus camaldulensis Dehnn., Gmelina arborea (Roxb) DC, Swietenia macrophylla King.) collected from the hilly areas of Chittagong University (CU) was investigated. Roots and rhizosphere soil samples were collected in different seasons (pre-monsoon, monsoon and post monsoon). Percentage of AM colonization in root and number of spores/100 gm dry soil were assessed. The result of the investigation reveals that the intensity and percentage of AM colonization varied in different forest tree species in different seasons. In this study, maximum AM colonization and spore population were found in pre-monsoon and minimum were in monsoon season. The intensity of colonization was maximum in C. tabularis (74.43%) in pre-monsoon, A. lebbeck (69.45%) in monsoon and S. macrophylla (67.8%) in post monsoon seasons and minimum in A. auriculiformis (53.75%) during pre-monsoon, A. saman (24.4%) in monsoon and A. saman (19.36%) in post monsoon. The number of spores found per 100 g dry soil ranged between 164-376 during pre-monsoon, 27-310 during monsoon and 194-299 in post monsoon season. Out of six recognized genera of AM fungi, Glomus, Sclerocystis, Entrophospora, Scutellospora, Acaulospora and other unidentified spores were observed.

• Journal of Embryo Transfer
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• v.24 no.2
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• pp.127-130
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• 2009

The purpose of this study was to determine the effect of cows parity and calving seasons on the subsequent reproductive performance of the herd of Korean native cows raised under the same condition. With the parity of the cows ranged 1 to 4 (mean: 1.9), significant associations were found between parity and calving interval (p<0.05). Calving interval of the primiparous cows group was 395.0 ${\pm}$ 16.5 days, which was the longest calving interval among the four groups. On the other hand, calving interval of the second parity group was 333.7 ${\pm}$ 3.6 days. The primiparous cows had tendencies that long interval from calving to conception and small number of service per conception relatively when compared with the multiparous cows. In the case of calving season, the interval from calving to first service was short in summer and winter relatively. The interval from calving to conception in summer was the shortest in four seasons. The number of service per conception was larger in spring and winter and smaller in summer and autumn. Calving in spring showed delayed reproductive performance and calving in summer showed desirable reproductive performance.

• Environmental Engineering Research
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• v.24 no.3
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• pp.501-512
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• 2019

The seasonal effects on the biostability of drinking water were investigated by comparing the seasonal variation of assimilable organic carbon (AOC) in full-scale water treatment process and adsorption of AOC by three filling materials in lab-scale column test. In full-scale, pre-chlorination and ozonation significantly increase $AOC_{P17\;(Pseudomonas\;fluorescens\;P17)}$ and $AOC_{NOX\;(Aquaspirillum\;sp.\;NOX)}$, respectively. AOC formation by oxidation could increase with temperature, but the increased AOC could affect the biostability of the following processes more significantly in winter than in warm seasons due to the low biodegradation in the pipes and the processes at low temperature. $AOC_{P17}$ was mainly removed by coagulation-sedimentation process, especially in cold season. Rapid filtration could effectively remove AOC only during warm seasons by primarily biodegradation, but biological activated carbon filtration could remove AOC in all seasons by biodegradation during warm season and by adsorption and bio-regeneration during cold season. The adsorption by granular activated carbon and anthracite showed inverse relationship with water temperature. The advanced treatment can contribute to enhance the biostability in the distribution system by reducing AOC formation potential and helping to maintain stable residual chlorine after post-chlorination.

• Journal of the Korean association of regional geographers
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• v.16 no.3
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• pp.216-223
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• 2010

The study deals with classification of drought-flood intensity using Z index based on the precipitation data in Hyesan of the past 50 years(1957~2006). The frequencies of years and four seasons of flood drought and their change features have also been analyzed based on tendency analysis and MESA and wavelet methods. Results show that the annual and seasonal frequencies of flood-drought exceed 24% in Hyesan and flood-drought disasters have been high frequency. Inter-decadal variability seems to be clear in autumn but those of inter-annual variability are obvious in other three seasons and years. Recently the probability of drought disaster become higher in autumn. The flood disaster in other three seasons and years are estimated to become higher in the future.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.5
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• pp.681-685
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• 2000

A computer software was developed in our laboratory to automatically control the pigs environment by the image analysis system (IAS), which monitors and analyzes the pig's behavior and feeds the results back to the computer hardware. Three feeding trials were conducted with growing pigs ($L{\times}Y$) to test the effectiveness of the IAS under various seasons. In all three trials, the open-sided conventional pens with half-slatted floor were used as controls; for the IAS treatment, fully-slatted floors were used in the windowless pens. Experiment 1 was conducted in the winter for 30 d with 24 growing pigs. There were two treatments (Conventional vs. IAS), and three pens (replicates) per treatment. During the growing period, the feed efficiency was significantly (p<0.05) improved by the IAS. In addition, the pigs reared under the IAS during the growing period displayed better growth rate during the finishing period than did the pigs reared under the conventional conditions. Experiment 2 was conducted in the summer for 30 d with 24 growing pigs. The experimental design was the same as Experiment 1. During the finishing period, all the pigs were kept in conventional open-sided pens until their market weights to evaluate their carcass characteristics. During the growing period, the growth rate and feed efficiency of the pigs in the IAS was better than those of the control pigs. In addition, various carcass characteristics were significantly improved by the IAS rearing during the growing period. Experiment 3 was conducted with 30 growing pigs for 30 d in the spring. The experimental design was the same as Experiment 1. No difference was found in growing performance between the control and IAS pigs. It could be concluded that the IAS is effective in providing optimum conditions for the growing pigs in summer and winter seasons. In addition, providing an optimum environment during the growing period results in improved growth rate, feed efficiency, and carcass qualities for the finishing pigs.

• Journal of the Korean Wood Science and Technology
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• v.14 no.3
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• pp.16-22
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• 1986

Effective air-drying days for four seasons and districts were calculated from average monthly temperature, relative humidity and wind speed records for 24 districts in Korea and air-drying calendars were prepared. And these districts were divided into zones of effective air-drying days. These results were as follows. 1. Effective air-drying days for four seasons were 20 to 23 days in springtime, 30 days in summertime, 21 to 26 days in autumntime, and 8 to 17 days in wintertime. 2. Effective air-drying days variated from district to district and was 237 days, the shortest period, in Ch'unch$\breve{o}$n, and was 288 days, the longest period, in-S$\breve{o}$gwipo. 3. Effective air-drying days were primarilly related to the difference in temperature from month to month, and secondarily, especially in September, were related to the differences in relative humidity, and were not related to wind speed. 4. South Korea was divided into 4 zones of effective air-drying days and these zones had it little difference compared with meteorological zones.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.6
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• pp.920-933
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• 2012

Marine algal flora and community structure were investigated seasonally at four stations in Busan, in which coastal area and estuary affected by Nakdong river are involved, from February 2011 to October 2011. Total 78 species including 9 of cholophyta, 17 of phaeophyta and 52 of rhodophyta were found during the study period. Maximum and minimum species number were recorded at station 1(57 species) and at 3(32 species). As based on the cluster analysis, grouping pattern between the four stations was significantly affected by season and Nakdong river run off. At station 3 directly exposured on Nakdong river run off, species diversity was relatively low and dominant species were similar throughout four seasons. However, coverage at the station was relatively high because of Ulva bloom. This difference results from salinity and nitrates concentrations closely related with river runoff controlled according to precipitation. Marine algal coverage was high at lower salinity and higher nitrate concentration. In conclusion, the spatio-temporal distribution of benthic marine algae in estuary of Nakdong river was mainly determined by the precipitation and river run off with the seasons, whereas that in coastal area was seasonally affected by general physical, chemical, biological and dynamic factors.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.231-231
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• 2020

Unlike conventional treatment technologies, the performance of nature-based facilities were susceptible to seasonal changes and climatological variabilities. This study evaluated the effects of seasonal variables on the treatment performance of constructed wetlands (CWs). Two CWs treating runoff and discharge from agricultural and livestock areas were monitored to determine the efficiency of the systems in reducing particulates, organics, and nutrients in the influent. For all four seasons, the mean effluent suspended solids concentration in the agricultural CW (ACW) increased by -2% to -39%. The occurrence of algal blooms in the system during summer and fall seasons resulted to the greatest increase in the amount of suspended materials in the overlying water. unlike ACW, the livestock CW (LCW) performed efficiently throughout the year, with mean suspended solids removal amounting to 61% to 68%. Algal blooms were still present in LCW seasonally; however, the constant inflow in the system limited the proliferation of phytoplankton through continuous flushing. The total nitrogen (TN) and total phosphorus (TP) removal efficiencies in ACW were higher during the summer (21% to 25%) and fall (8% to 21%) seasons since phytoplankton utilize nitrogen and phosphorus during the early stages of phytoplankton blooms. In the case of LCW, the most efficient reduction in TN (24%) and TP (54%) concentrations were also noted in summer, which can be attributed to the favorable environmental conditions for microbial activities. The mean removal of organics in ACW was lowest during summer season (-52% to 35%), wherein the onset of algal decay triggered a relative increase in organic matter and stimulate bacterial growth. The removal of organics in LCW was highest (54 % to 55%) during the fall and winter seasons since low water temperatures may limit the persistence of various algal species. Variations in environmental conditions due to seasonal changes can greatly affect the performance of CW systems. This study effectively established the contributory factors affecting the feasibility of utilizing CW systems for treating agricultural and livestock discharges and runoff.

• The Korean Journal of Ecology
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• v.24 no.6
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• pp.353-357
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• 2001

Differential response of genotypes to temporal environmental heterogeneity may contribute to the long-term persistence of these genotypes within a population. In this experiment, we experimentally tested whether groups by season interactions for germination and seedling growth can explain genetic variability within the population. To determine whether seeds collected during the four seasons respond differentially to temperature treatments, two-way ANOVA was performed. This study indicates that seasonal environments have large effects on demography. Groups within populations respond differentially to seasonal environments by influencing population growth that may in turn influence community composition. Most importantly, the study showed that temporal heterogeneity in the environment might functions as a mechanism that maintains within-population genetic diversity.