• Current Research on Agriculture and Life Sciences
• /
• v.4
• /
• pp.141-153
• /
• 1986

This study intends to document the existing cyclical fluctuations of garic and onion price at farm gate level during the period of 1966-1986 in Korea. The existing patterns of such cyclical fluctuations were estimated systematically by removing the seasonal fluctuation and irregular movement as well as secular trend from the original price through the moving average method. It was found that the cyclical fluctuations of garic and onion prices repeated six and seven times respectively during the same period, also the amplitude coefficient of cyclical fluctuations showed speed up in recent years. It was noticed that the cyclical fluctuations of price in onion was higher than that of in garic.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.16 no.4
• /
• pp.321-337
• /
• 2010

Long-term trends and distribution patterns of water quality were investigated in the Mokpo coastal areas of the Yellow Sea, Korea from 1979 to 2009. Water samples were collected at 5 stations and physicochemical parameters were analyzed including water temperature, salinity, suspended solids (SS), chemical oxygen demand (COD), dissolved oxygen (DO) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 30 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 3 clusters by PCA; station cluster 1, 2~4, and 5. Annual water qualities were clearly discriminated into 4 surface water clusters and 2 bottom water clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, pH and COD tended to increase from late 1980's, salinity to decrease, phosphate to increase from 1994 and dissolved inorganic nitrogen to increase, due to the input of fresh water same as shown in Kyoungin coastal area, Asan coastal area, Choensoo bay and Gunsan coastal area.

• Korean Journal of Environmental Biology
• /
• v.22
• /
• pp.86-92
• /
• 2004

The marine viral density in the Gwangyang Bay was abundant about 2.0${\times}$10$^{8}$ particles ml$^{-1}$ . For each season, viral abundances were recorded from 9.0${\times}$10$^{8}$ particles ml$^{-1}$ in summer to 0.7${\times}$10$^{6}$ particles ml$^{-1}$ in winter. The spatial distributions of the viral, bacterial and phytoplankton biomass in the Gwangyang Bay were mostly highey in closed estuarine system (Station 2, 5, 10, 12, 16, 20) than open ocean system (Station 28, 38, 42, 46, 51), And the othey closed estuarine system (Station 22, 26, 32, 34) indicated higher viral abundances, lower bacterial and plankton biomass than open oceanic system. In depths of some stations, the bacterial abundances exceeded a hundred fold than viral abundances. Seasonal abundances of marine viruses and their host systems were dynamically changed, and their seasonal variations were closely correlated. In summer, viral and bacterial abundances were increased, and phytoplankton chlorophyll $\alpha$ concentrations were maintained in average values. In winter, viral and bacterial abundances were dramatically decreased, and chlorophyll a concentrations were decreased, but, immediately increased. The viral abundances were peaked in August 2001, and bacteyial abundance, in August 2001 and June 2002, while chlorophyll a concentrations were peaked in April. 2002. In total host and viral abundances, it was seemed that their pools were maintained to steady-states by viral mortality, and viral abundance maintained steady-states. In our assessments, this report is a unique research about marine viral ecology of the Gwangyang Bay in Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.17 no.1
• /
• pp.16-24
• /
• 2012

To study the seasonal pattern of sediment distribution and the transport tendency in Haeundae nearshore area; i) the grain size texture of surface sediment was examined in June, October, and December of 2007, and March and June of 2008, and secondary, ii) the transport tendency was studied by using a two-dimensional sediment transport model of Gao and Collins (1992), and finally, iii) the bathymetric changes were analyzed by using the data collected in February, May, August, and December of 2007 by Haeundae District Office. Spatial distribution of sediment texture, the tendency of sediment transport as well as the bathymetric change showed significant seasonal variations. From June to December of 2007, the eastern part of the Haeundae area, off Dalmaji Hill showed the coarsening of mean grain size with a prominent transport tendency toward the Haeundae beach. On the contrary, the western part of the area, off Dongbaek Island showed a fining trend of mean grain size, and the transport tendency toward the beach was relatively weakened. From December of 2007 to June of 2008, the mean grain size of Mipo Harbor became finer, and the transport tendency toward the central beach decreased. The mean grain size of Dongbaek Island became coarser, while the tendency increased in the direction of the beach. The areas of significant net accumulation and erosion were depicted based on the bathymetric changes between observation periods. During the period of February to May of 2007, net accumulation was observed on the eastern part of the study area, in front of Mipo Harbor. Erosion was generally occurred throughout the area from May to August of 2007. From August to December of 2007, erosion and accumulation was observed off Mipo Harbor and Dongbaek Island, respectively. The change of sediment facies also suggests the accumulation on the eastern coast during the spring, erosion around the entire coast during the summer, and accumulation on the western coast during the winter. The changes in the accumulation and erosion were most apparent during the summer when several typhoons have passed by, while unnoticeable during the spring.

• Korean Journal of Ecology and Environment
• /
• v.51 no.4
• /
• pp.259-267
• /
• 2018

This study was conducted to confirm phenological response of main deciduous woody species in Korea according to elevated temperature. Based on seeds collected from the same place, 39 woody species were cultivated in field (control) and in greenhouse (treatment) that was maintained above base temperature ($4.8^{\circ}C$). And then, we observed phenotype change of leaves focused on phenological response and explained relation with their current distribution area. As a result, initiation period of leaves unfolding was 1st~3rd, May in control. It was 13, December~7, January in treatment. Period of leaves yellowing was 11~26, October in control. It was 30, October~13, November in treatment. Consequently, initiation period of leaves unfolding was faster by 119~140 days and period of leaves yellowing was slower by 3~32 days since elevated temperature. Period of leaves growth increased in treatment by 148 days than control. Quercus mongolica and Quercus serrata that cultivated in treatment was changed as evergreen trees which have grown up continuely during one year. Also, initiation period of leaves unfolding of Sorbus alnifolia in treatment was faster than in control. However, difference of the period between control and treatment was smallest. Because period of yellowing leaves was moved ahead. Phenological response of leaves according to elevated temperature had no relation of type of their current distribution area. This is the result of acclimation due to elevated temperature during the winter and suggests that the phenotype of leaves of 39 deciduous woody species is more sensitive to the current growth condition than to the past growth condition.

• Korean Journal of Ecology and Environment
• /
• v.39 no.4 s.118
• /
• pp.498-507
• /
• 2006

The main objective of present study was to evaluate how seasonal rainfall influenced natural habitat conditions of 10 metric habitat variables along with ionic conditions and suspended solids in the Woopo Wetland during August 2002-July 2003. Largest spatial variabilities in total suspended solids (TSS) occurred during the summer monsoon and the inorganic suspended solids (ISS), expressed as a inorganic proportion of total solids, showed linearly increasing trend from the upstream to downstream. This phenomenon was mainly attributed to counter flow of turbid water from the main Nakdong-River. During the flooding, ISS : TSS ratio showed large increases (92%) in the downstream than the upstream (43%). For this reason, transparency declined (mean=0.13 m, range=0.08-0.21 m) largely in the downstream reach and thus, chlorophyll-a concentration showed low values (range: $4.2-8.6\;{\mu}g\;L^{-1}$), indicating a direct influence on primary productivity or algal growth by inorganic turbidity. In the 2nd survey, ISS averaged 4.0 mg $L^{-1}$ (3.3-4.8 mg $L^{-1}$), thus the ISS decreased by 14 fold, compared to the ISS in the 1st survey during the flooding, while organic suspended solids (OSS) values were greater than those of ISS, indicating a dominance of organic solids. This condition was similar to solid contents in the 3rd survey, but showed a large difference compared to the 4th survey during the growing season. Habitat health assessments, based on 10 metric habitat variables, showed that QHEI values were greatest in the growing season (May) than any other seasons and largest spatial variations occurred in the 2nd survey. Overall, dataset suggest that seasonal episodic flooding during the monsoon may largely contribute nutrient cycling and sediment contents in the Woopo Wetland and Topyung Stream.

• Journal of Wetlands Research
• /
• v.14 no.1
• /
• pp.121-130
• /
• 2012

This study is to investigate the removal rates of nutrient in water, the biomass of water plants, and the total amounts of T-N and T-P uptakes by water plants to evaluate the ecological characteristics of the constructed wetland for treatment of livestock wastewater in Yangji-ri, Nonsan-si from June through November 2011. During the experimental period, the monthly plant biomass of constructed wetland in July were the highest as 669.4 kg, while the lowest in November as 200.1 kg. The research showed that the average nitrogen and phosphorus contents in aboveground and underground biomass of Phragmites australis were $21.9{\pm}0.6{\sim}32.1{\pm}1.5mg/g$, $15.1{\pm}5.5{\sim}24.9{\pm}5.7mg/g$, $1.5{\pm}0.3{\sim}2.4{\pm}0.2mg/g$ and $1.6{\pm}0.6{\sim}2.5{\pm}0.6mg/g$, respectively. The maximum amount of T-N and T-P uptake by Phragmites australis were 28.0 kg in July and 2.5 kg in June, respectively, while the minimum amount of T-N and T-P uptake by Phragmites australis were 9.7 kg and 0.7 kg in November, respectively. The removal rates of T-N and T-P in constructed wetland for treating livestock wastewater were 23.0 % and 59.1 %, respectively. The results of this study is expected to deduce the circulation of contaminants and nutrient in the wetland afterwards.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.15 no.3
• /
• pp.179-185
• /
• 2009

The species composition and distributional patterns in marine benthic algae at intertidal zone in Masan Bay were investigated seasonally throughout 2007. A total of 42 species, 5 Chlorophyta 8 Phaeophyta and 29 Rhodophyta were recorded, and dominant species were Enteromorpha linza, Ulva pertusa, Sargassum thunbergii, Gelidium amansii, G. divaricatum, Corallina pilulifera, Gracilaria textorii, and Polysiphonia morrowii during study periods. Especially the vertical distribution of dominant algal species was remarkable: U. pertusa and G. divaricatum were dominated in the upper part, E. intestinalis, E. linza, S. thunbergii and G. divaricatum were in the middle part, and U. pertusa, Undaria pinnatiffda, S. thunbergii, G. amansii, G. divaricatum and C. pilulifera mainly occurred in the low part of tidal zone. The numbers of species were different with seasons and stations; Higher number of species was 38 species in winter, whereas 28 species were the lowest in fall. The number of species was higher at stations 4 and 6 Mile the lower value was at stations 1 and 2 than other stations. The spatial distributional patterns of marine benthic algal composition at each station in dendrogram and MDS ordination were due to the differences of local topography and physical characteristics such as currents and water movements.

• Food Science and Preservation
• /
• v.11 no.3
• /
• pp.313-318
• /
• 2004

This study was conducted to compare development of browning in minimally processed mushrooms (Agaricus bisporus Sing.) by picking season and postharvest holding time of the raw material. 'White' type of the mushrooms were harvested and minimally processed immediately after harvest or holding at 2$^{\circ}C$ for 7 days after picking in 4 seasons. The processed mushrooms were kept at 5$^{\circ}C$, and changes in surface color and content of total phenolic compounds of the mushrooms were measured. Respiration rate of the whole mushrooms was ranged from 9.55 to 17.93 mL C0$_{2}$/kg$\cdot$ hr, and the rate was low in mushrooms harvested in summer and autumn compared with those picked in spring and winter. Hunter L value of the mushrooms decreased rapidly just after slicing, especially in summer-harvest mushrooms. The mushrooms processed with the raw materials stored at 2$^{\circ}C$ for 7 days after harvest showed the lowest 'L' value among the sliced mushrooms prepared at different holding time. Consequently, summer-harvest mushrooms and the mushrooms kept at 2$^{\circ}C$ for more than 7 days after harvest would be unsuitable for minimally processing due to rapid browning.

• Parasites, Hosts and Diseases
• /
• v.30 no.4
• /
• pp.341-348
• /
• 1992

Because no reference on trombiculid mites (Acarina: Trombiculidae) in Cheju Island where tsutsugamushi disease is highly endemic had been available, studies on trombiculid mites in Cheju Island were implemented during the period of August 1991-Apil 1992, and the results obtained are summarized as follows: (1) The species and numbers of the field rodents collected were 143 Apodemus agrarius chejuensis (92.3%), 11 Crocidura lasiura (7. l%) and 1 Micromys minutus (0.6%) From total 12,075 chiggers harvested, 9 species of 4 genera in Trombiculidae were identified. (2) The predominant species through all seasons was 1. setum (43.3%), followed by 1. orientale (27.4%) and 1. scutellare (26.6%). However, in autumn when the most cases of tsutsugamushi disease occur, 1. scutellere was prominently predominant, having 79.8% of the collected chiggers. (3) Among 1,1421. scutellare examined for Rickettsia tsutsugpmushi by means of IFA test, 6 individuals were found positive showing 0.5% of infection rate. This is the first finding that 1. scutellere is the second vector species of tsutsugamushi disease in Korea. (4) Antibody positive rate of A. agrarius chejuensis sera were 31.2% (44/139), and 1 M. minutes serum was also found positive. The seropositive rates by season were not so significantly different. Key words: Tsutsugamushi disease, epidemiology, vector species, Cheju Island, Korea.