• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.223-230
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• 1994

A practical study on a drying and fermentation system equipped with a stirring machine operated mechanically, of pig manure was conducted to prove the efficiency of and practicability to an ordinary pig farm. The type of the drying bed was a round-shaped (r=3m) concrete structure and the stirring machine was adopted to stir and transfer dried pig manure to the fermentation tank. The dried pig manure was put into a fermentation tank ($V=18m^3$), which was aerated from pipe lines installed at the bottom. While water content of pig manure passing through a drying bed was remarkably reduced than before drying, the drying efficiency of this system decreased in winter. However, the temperature of pig manure piled up in the fermentation room in winter reached over $60^{\circ}C$ and excess water of pig manure was removed during the fermentation process. The reduction rate of water content of pig manure, to which dried pig manure was added as bulking material on the drying bed, was 52.1%, but when dried without bulking material it was only 19.7%. Although the content of $P_2O_5$ of dried pig manure was slightly higher than that of fresh pig manure, progressive changes in chemical composition between fresh and dried pig manure made no great difference. Among the contents of minerals of fresh and dried pig manure, CaO was the highest and the rest were in the decreasing order of $K_2O$, MgO, and $Na_2O$. Population density of E. coli and Streptococci of dried pig manure was reduced by 142 and 236 times that of fresh pig manure, respectively. The installation cost of this drying and fermentation system was 4,185,630 won (approximately 5,232 US $) and operating cost per year was 190,000 won (237.5US $) on the basis of self-labor condition.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.223-231
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• 2012

The purpose of this study is to investigate basically the mechanism of heat transfer by the resolution of complex fluid flow inside a sophisticated designed screw dryer for the treatment of sewage sludge by using numerical analysis and experimental study. By doing this, the result was quite helpful to obtain the design criteria for enhancing drying efficiency, thereby achieving the optimal design of a multiple screw type dryer for treating inorganic and organic sludge wastes. One notable design feature of the dryer was to bypass a certain of fraction of the hot combustion gases into the bottom of the screw cylinder, by the fluid flow induction, across the delicately designed holes on the screw surface to agitate internally the sticky sludges. This offers many benefits not only in the enhancement of thermal efficiency even for the high viscosity material but also greater flexibility in the application of system design and operation. However, one careful precaution was made in operation in that when distributing the hot flue gas over the lump of sludge for internal agitation not to make any pore blocking and to avoid too much pressure drop caused by inertial resistance across the lump of sludge. The optimal retention time for rotating the screw at 1 rpm in order to treat 200 kg/hr of sewage sludge was determined empirically about 100 minutes. The corresponding optimal heat source was found to be 150,000 kcal/hr. A series of numerical calculation is performed to resolve flow characteristics in order to assist in the system design as function of important system and operational variables. The numerical calculation is successfully evaluated against experimental temperature profile and flow field characteristics. In general, the calculation results are physically reasonable and consistent in parametric study. In further studies, more quantitative data analyses such as pressure drop across the type and loading of drying sludge will be made for the system evaluation in experiment and calculation.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.197-213
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• 2012

This study was performed to know the community structure of macrobenthos and environmental factors at each 16 stations in the subtidal sandy bottoms of the southern coastal water of Jeju Island from July to November, 2011. Mean temperature and mean salinity were $20.2-22.7^{\circ}C$, 33.7-34.9 psu which shows stable water messes. Chlorophyll a concentrations of phytoplankton ranged from 0.71 to 1.71 mg/L (1.11 mg/L), showing higher July than September and November with a blooming in summer. The mean concentration values (the ranges in parentheses) of nitrate, phosphate, and silicate are 0.029-0.206 mg/L (0.101 mg/L), 0.001-0.027 mg/L (0.007 mg/L), 0.024-0.682 mg/L (0.454 mg/L), respectively. However, the values higher coastal zone due to influxes from the land. A total of 37 species was identified. of these mollusca comprised 29 secies (78.4%); Echinodermata 5 (13.5%); Arthropoda 3 (8.1%). density and biomass were estimated to be 550 ind./$m^2$ and 20,951.8 gwwt/$m^2$, respectively. Mollusca were the most dominant faunal group in terms of abundance (481 ind./$m^2$) and number of species as well, whereas bivalves were predominant in biomass (16,647.6 gwwt/$m^2$). The dominant species were Vasticardium burchardi, Oblimopa japonica, Mactar achatina, Bornatemishistrioiw akawai, Paphia vernicosa, Amusium japonicum, Glycymeris albolineata, Astriclypeus manni in 15-30 m. The seasonal variation appeared as distinct, Mollusca of individual and biomass. When summer was make a slow increase, after the highest decrease in autumn. The abundance of macrobenthic invertebrates showed significant correlation with environmental factors (Chlorophyll a, DIN, $SiO_2$, Fine sand, Very fine sand) in almost all sampling depths. The biodiversity, evenness richness index were appeared 1.56-2.50 (H'), 0.49-0.80 (E'), 4.12-4.67 (R) in each stations. The dominace index were appeared Highest in November and lowest in September.

• Journal of Aquaculture
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• v.5 no.1
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• pp.93-108
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• 1992

This study was conducted to understand the variation of suspended matters in coastal waters of Cheju Island. Water sampling was carried out at 22 stations along the coast of this island from March 1988 to November 1989. Analyzed and/or observed items were water temperature, salinity, total solids (TS), total dissolved solids (TDS), volatile suspended solids (VSS), and fixed suspended solids (FSS). Inter-relationships between wind velocity, precipitation and total suspended solids (TSS) were also investigated. More windy days prevail in winter season (December, January and February) in Cheju Island. Thirty-six points seven percent of total windy days of a year appeared in this season. The rate of windy days in spring was $27.3\%$ and those in summer and fall were $17.9{\%}$ each. From February to July, the heaviest precipitation was observed in the southeastern area and that from August to January was observed in the eastern part of this island. TS and TDS were firmly related with the fluctuation of salinity. Therefore, there were higher in spring and lower in summer. The highest TSS (7.73 $mg/{\ell}$) was observed in February and was the lowest (4.73 $mg/{\ell}$) in September. Annual mean value of TSS was 6.3$mg/{\ell}$. The highest VSS (2.03 $mg/{\ell}$) was observed in July and lowest (1.42 $mg/{\ell}$) in September. The percentage of VSS per 755 was $30.6{\%}$ in average that was not much higher level compared to the other polluted areas. This value became higher in summer (av. $34.17{\%}$) and lower in winter (av. $24.2{\%}$). Fluctuation of TSS was mainly related with the freshwate. discharge, tidal action, and re-suspension of bottom sediments by the wind waves. Therefore, TSS concentration was low in summer and hish in winter.

• Journal of Aquaculture
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• v.11 no.2
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• pp.193-201
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• 1998

This study was carried out to investigate the enviromental quality and the growth of transplanted pen shell, Atrinna pectinata japonica. Followings are the results of growth of transplanted pen shell with respect to the shell size groups from the natural habitat (Usando) in May 1995, and cultivated upto November in the transplantated area (Soomoonri). The water depth of transplantated area andnatural habitat were 3m, 20~25m, respectively. The seawater temperature of the two culturing farms were ranged of 10.9~$27.8^{\circ}C.$, 8.5~$30.0^{\circ}C.$, respectively at the lowest in November adn the highest in July. The seawater salinity of the two areas were ranged of 29.54~35.26$^0\prime\infty$, 28.75~36.31$^0\prime\infty$, respectively at the lowest in July and the highest in November. The phosphoric acid ($PO_4$-P) of the two areas were 0.09~$1.14 ^{\mu}$g-at/l, 0.23~$1.33 ^{\mu}$g-at/l, respectively at the lowest in June and the highest in September. The bottom type of the two areas was a silty mud, 85.23% (82.17~87.26%) in natural habitat and 92.12% (90.76~92.94$^0\prime\infty$) in transplanted area. In this study area, phytoplankton were composed of 19 species. Of these 19 species, Skeletonema costatum was dominant species in seawater between natural habitat and transplantatied area, and 157 cells/ml, 165 cells/ml at August respectively. Stock of phytoplankton in transplantated area were more than those of natural habitat except June and November. The growth of shell length, shell height, total weight, soft part weight and posterior adductor muscle weight of pen shell on different size groups (SL 10, 10~15, 15~20, 20cm) were excellent in shell length of 10cm group, and 99.32%, 107.66%, 871.09%, 951.26% and 1,223.76%, respectively. The survival rate of pen shell was 98.10% in the shell length of 10cm groups, 90.35~94.76% in the others groups. The growth of shell length, total weight, soft part weight and posterior adductor muscle weight of pen shell in transplantated area were more 1.3, 2.6, 2.7 and 4.5 times than those of natural habitat.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.1
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• pp.88-97
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• 1999

The distributional characteristics of chlorophyll-a and their relationship to the oceanographic condition were investigated in the northern part of East China Sea in February, May, August and November during 1995$\~$1997. The temperature and salinity were high in the eastern area and low in the western area. Thermocline and halocline were strongly formed at the 50 m depth in August. Dissolved oxygen was low in August with value of 3.77 ml/$\ell$, particularly in the near coast of East China, where dissolved oxygen was less than 2.0 ml/$\ell$. Transparency was high in May while low in February. Total nitrogen and phosphate concentrations were high in November while silicate concentrations was high in August. They showed the seasonal variations. Total nitrogen and phosphate revealed high concentrations in the near coast of East China, where the salinity was the lowest. Especially, total nitrogen and silicate were higher in August than the other survey months in the near coast of East China. Phosphate showed the even distributional pattern. Chlorophyll-a appeared high in August with 0.512$\mu$g/$\ell$ and low in February with 0.372$\mu$g/$\ell$. Annual means in each survey depth was high at the 10m depth with 0.632 $\mu$g/$\ell$ and gradually decreased toward the more deep depth. But the cencentrations at 150m depth near the bottom again increased as 0.243 $\mu$g/$\ell$. In the seasonal patterns of vortical distribution of chlorophyll-a, the maximum depth value was surface in February, 30 m in May, 10 m in August and 20 m in November. Transparency showed the highest value in May. It means that there are the close relationship between the vertical distribution of chlorophyll-a and transparency.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.3
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• pp.369-374
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• 2014

The rice stem borer (Chilo suppressalis Walker) was one of the most destructive pest of rice for the 1960s and 1970s in Korea. Recently, it is newly recognized as a potential risk factor to the biomass yield of bioenergy crops. The current research was firstly conducted to investigate overwintering larvae population density and pattern of rice stem borer attacking Miscanthus sacchariflorus cv. Geodae 1 which is referred to as an ideal lignocellulosic bioenergy crop in Korea. Population density of larvae per $1m^2$ in stems and rhizomes at the Miscanthus experimental plots and rates of damage (wormhole, abscission) of M. sacchariflorus cv. Goedae 1 were investigated from October 2012 to March 2013. The population of larvae per $1m^2$ in stems of Miscanthus were 23, 4, 1, and 1 in October, November, December 2012, and January 2013, respectively. Over the same period, the population of larvae in basal stem rots and rhizomes were increased, whereas decreased in stems. Interestingly, the positions of larvae for overwintering in Miscanthus were confirmed to 5~10 cm below the soil surface such as basal stem rot and rhizome, whereas the most common overwintering position known in rice is a part of stem on the ground such as rice straw and rice stubble. It would suggest that the larvae gradually moved to bottom of stems and rhizomes in soil in line with decline in temperature. Moreover, the damage rates of stems per $1m^2$ were up to more than 50% in some places. In conclusion, this might be the first report that rice stem borer could affect the productivity of biomass of Miscanthus in case of mass cultivation. Moreover, it should be necessary to make a decision in insect control management for this bioenergy feedstock and other related crops.

• Korean Journal of Environmental Biology
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• v.18 no.4
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• pp.403-409
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• 2000

Surface and bottom water samples were collected from 10 stations located in the coastal area of Tongyong in April, August and October 2000. Distribution of heterotrophic bacteria, coliform bacteria and fungi in the sea water samples was investigated by measuring the corresponding viable cell number according to the plate counting method. Heterotrophic bacteria in the surface water counted 3.1$\times$10$^2$- 4.0$\times$10$^3$cfu ml$\^$-1/, 2.7$\times$10$^3$- 1.2$\times$10$\^$5/cfu ml$\^$-1/ and 1.3$\times$10$^2$- 7.2$\times$10$^2$cfu ml$\^$-1/ in April, August and October, respectively. The cell number of coliform bacteria in the surface water amounted to 0-1.5$\times$10$^1$cfu ml$\^$-1/, 3.5$\times$10$^1$- 5.2$\times$10$^3$cfu ml$\^$-1/ and 0-1.8$\times$10$^2$cfu ml$\^$-1/ in April, August and October, respectively. As for fungi, the cell number in the surface water was 0-3.0$\times$10$^1$propagules ml$\^$-1/, 3.0$\times$10$^1$- 8.0$\times$10$^1$ propagules ml$\^$-1/ and 0-2.2$\times$10$^1$ propagules ml$\^$-1/ in April, August and October respectively. The surface water samples from the station 3 in August were added with feed stuffs for fish as much as 0.01 gl$\^$-1/, 0.1 gl$\^$-1/ and 1 gl$\^$-1/ and cultured at 5$\^{C}$, 15$\^{C}$, 25$\^{C}$ and 35$\^{C}$. Microbial cells were not isolated at all when the culturing temperature was 5$\^{C}$. However, the microbial cell number increased significantly in all the surface water samples containing 1 gl$\^$-1/ of the feed stuffs when cultured at 15$\^{C}$, 25$\^{C}$ and 35$\^{C}$

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.340-349
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• 2009

The natural type section of Gap Stream was divided into 7 sites, such as, closed pool, runs, riffle, opened pool, pool, reek-scattered riffle, and Dam-type pool. The ecological characteristics of fish community at each site was examined from April, 2007 to October, 2008. During the survey period, 29 species belonging to 8 families were collected, and Carassius auratus (St. 1), Coreoleuciscus splendidus (St. 3), Acheilognathus lanceolatus (St. 4) and Zacco platypus (St. 2, 5, 6, 7) were characteristic species that represent each habitat. The species of C. auratus preferred physical habitat with sand-bottom pool, moderate depth of 65$\sim$90 cm, and stagnant water. The species of C. splendidus mainly preferred physical habitat with cobbles and pebbles are scattered riffles (St. 3), moderate depth of 65$\sim$90 cm, and flow velocity is 0.14$\sim$0.85 m $sec^{-1}$. It also preferred where concentration of BOD, COD, TN, TP and SS is low and DO's value is high, because the flow velocity is fast. A. lanceolatus preferred where the depth of water is low (3$\sim$44 cm) like an opened pool (St. 4) and the flow velocity is slow (0.01$\sim$0.02 m $sec^{-1}$). Z. platypus dominated in a variety of habitats such as runs (St. 2), pool (St. 5), rock-scattered riffles (St. 6) and D-type pool (St. 7), and it preferred places where flow is abundant and riverbed structure is diverse. On the other hand, 4 individuals of Iksookimia choii appeared at reek-scattered riffles (St. 6). I. choii appeared in this research lived in where the width of river is 24 m, the depth of water is 3$\sim$35 cm and the flow velocity is 0.01$\sim$0.49 m $sec^{-1}$, and riverbed structure was diversely formed with boulder to sand. Also, water temperature, EC, BOD, COD, TN and TP was low, but concentrations of DO and SS were high comparatively. Therefore, it seems that I. choii can live only in physical and chemical environment with similar conditions.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.1
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• pp.44-57
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• 2003

Seasonal variations of bacterial abundance and production, heterotrophic nanoflagellate (HNF) abundance and HNF ingestion rates on bacteria using FLB together with environmental variables were investigated at intervals of a month in Kyeonggi Bay from December 1991 to November 1998. Bacterial abundance and production ranged from 0.38$\times$10$^{9}$ ~ 3.25$\times$10$^{9}$ cells 1$^{-1}$ (average 1.19$\pm$0.69$\times$10$^{9}$ cells 1$^{-1}$ ) and from 1.51 to 20.4 cells 1$^{-1}$ h$^{-1}$ (average 6.04$\pm$ 1.88$\times$10$^{6}$ cells 1$^{-1}$ h$^{-1}$ ), respectively. Bacterial abundance and production showed no differences at the high tide and low tide, and bacterial abundances were not different with depth, but bacterial production decreased with depth. Seasonal variation of bacterial abundance showed almost similar fluctuation pattern to those of DOC (dissolved organic carbon). HNF abundances ranged from 388 to 4,374 cells ml$^{-1}$ (average 1,344$\pm$130 cells ml$^{-1}$ ), were high in March, April, July and August. HNF abundance showed no difference between the high tide and low tide, and was not different with depth. The ingestion rates of HNF on bacteria were 1.0 to 6.3$\pm$10$^{6}$ bacteria 1$^{-1}$ h$^{-1}$ (average 3.12$\pm$0.55$\times$10$^{6}$ bacteria 1$^{-1}$ h$^{-1}$ ), resulting ingestion rates of HNF removed 19.4 to 141.4 %(average 62.3$\pm$12.0%) of bacterial production. Ingestion rates and grazing pressure of HNF on bacteria showed high correlation with HNF abundance. Although we cannot exactly discussion about seasonal variation of bacteria community in this study area where physical and chemical parameters were very complex, the results indicate that bacterial abundance and production were mainly controlled by resources supply as dissolved organic carbon and chlorophyll-a(bottom-up) except March which bacterial abundance and production uncoupled chlorophyll-a because of low dissolved organic carbon and low temperature, and were controlled by HNF grazing pressure(top-down) in the warm seasons except the winter.