• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.248-255
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• 2011

For the environmental friendly soil management on the cultivation of crops in the greenhouse, organic materials, such as the by product-fertilizer derived from livestock manure, rice straw, mushroom media, rice hulls, wood sawdust, and cocopeat, were used as carbon sources adjusting the ratio of carbon to nitrogen to 10, 20, and 30 based on the inorganic soil N. In each C/N ratio of greenhouse soil, watermelon was cultivated in the greenhouse as crop for experiment for the spring and summer of the year and the experimental results were summarized as follows. The concentration of T-C in the organic materials applied were between $289{\sim}429g\;kg^{-1}$, In the C/N ratio of 10, using watermelon as the crop cultivated during the second half of the year in the greenhouse soil, the $NO_3$-N and EC were reduced by 21 to 37%, and 26 to 33%, respectively, except the by product-fertilizer from livestock manure, compared to the soil $NO_3$-N and EC used in the experiment. After the watermelon was cultivated in soils that C/N ratios were controlled as 10, 20, and 30 with wood sawdust adding as carbon sources in the three soils with the different EC values, EC values of the soils were reduced by 33, 42, and 39%, respectively, compared to the soil EC used in the experiment. The weight of watermelon was 10.1-13.4 kg per one unit, and, of the three soils with different EC values. In the soils with three different EC values controlled at C/N ratio of 20, the weight of watermelon was good. The degree of sugar of watermelon were 11.8 to 12.3 Brix, which means that the difference between the treatments was not significant. In conclusion, the C/N ratio of 20 controlled by the proper supply of organic materials according to the representative EC values shown in the greenhouse soils was optimal condition enough to maintain the soil management for the organic culture with the proper nutrient cycling.

• Korean Journal of Environment and Ecology
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• v.22 no.3
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• pp.230-240
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• 2008

The primary aim of this study is to estimate the home range of a pair of raccoon dogs(Nyctereutes procyonoides koreensis) and to compare with the previous study of raccoon dogs in a rural area of Gurye, the southern part of South Korea. Radiotracking was regularly carried out on 2 raccoon dogs for 2 days every 2 months(in June, August, October and December, 2006). During the 2 days, radiotracking was usually conducted every $1{\sim}3$ hours through day and night. The analysis of tracking data with a total of $46{\sim}64$ bearings showed that the total home range size of the pair was $0.41km^2$, and mean home range size was $0.32km^2$ by 95% minimum convex polygons(MCP) estimate. The home ranges of the male and female were largely overlapping(about $70{\sim}95%$), and the sizes were not very much different from each other. However, there was a big difference between day $(0.01km^2)$ and night-time $(0.35km^2)$ home ranges, and it was largest in summer$(0.56km^2)$ and smallest in winter $(<0.01km^2)$. In addition, the home range of the pair included 1 core area and 4 different feeding areas. In conclusion, our raccoon dog home range data using the same individuals but with more frequent bearings per day and more extended tracking intervals still showed very similar results to the previous study with less frequent bearings per day and more extensive tracking days.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.294-303
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• 2020

This study aimed to examine was conducted to the ability of microclimate control in old pine forests by surveying pine forest in Buddhist temples, where the pine forest are stably growing through active protection in the Gyeongnam region, and comparing variation characteristics of microclimate characteristics (temperature and humidity) and distribution of vegetation type. The study sites were pine forests protected well by Buddhist temples (Haein-sa, Beomeo-sa, Tongdo-sa, and Bulguk-sa) in the southeast region of Korea and thus known for stably growing young pine trees. According to the vegetation distribution status analysis, these pine forests did not have a high ratio of pine trees. Except for Tongdo-sa, the ratio of deciduous forest and mixed (deciduous and pine trees) forest had a much larger presence than that of pine forest. Measured data of microclimate showed that the Tongdo-sa area had significantly different characteristics compared to the other three areas. Tongdo-sa area showed a significantly higher diurnal range of temperatures and humidity than the other three areas, in both spring and summer. It is due to the difference in vegetation management. The forests around Tongdo-sa are mostly pine forests, except for the developed areas, while those in the other three areas have a dominant ratio of deciduous brad-leaved forests. Intensive control of pine forest is not effective in mitigating microclimate, i.e., temperature and air humidity. Stress caused by rising temperatures and decreasing air humidity is blamed for the decline of pine forests. Thus, the current active management of pine forests, such as the Tongdo-sa case, has been found to have a greater negative impact on the temperature and humidity stress. Therefore, we believe that a new change in forest management is necessary to increase the effect of mitigating the microclimate of pine forests.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.59-67
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• 1995

This study was conducted to develope the automatic insulation system which control inside temperature of the greenhouse. For this purpose, the double- wall greenhouse and system which could automatically supply and discharge styrene pellets were constructed and abrasion of the pellets, blower ability, insulating property, transmittance and shading effect were analyzed by the experiments. The results obtained from this study can be summarized as follows : 1. It took an hour and fifteen minutes to supply and discharge about 2㎥ pellets in the experimental greenhouse. However, it is possible to reduce the operation time by proper selection of the blower and exhaust port, and by proper control of the supply and return pipe. 2. It was founded that the indirect delivery way was more profitable than the direct one in the supply and return of pellets. 3. When the transmittance was measured between 10 a.m. and 3 p.m., the average light transmissivity rate was 67%. 4. In winter nighttime, the inside temperature of the double- wall greenhouse with out the pellets was higher than the outside temperature by 3.4$^{\circ}C$ on an average. However, the inside temperature of the double - wall greenhouse with insulated area 73% was higher than the outside by one 6.6$^{\circ}C$ on an average, and the inside temperature of the greenhouse with insulated area 100% was higher than outside one by 13.5$^{\circ}C$ on an average. Therefore, it was proved that the insulating ability of the double - wall greenhouse in nighttime was excellent. 5. When the outside temperature was 36.9$^{\circ}C$ on an average, the inside temperature of the double- wail greenhouse with insulated area 100% was 3$0^{\circ}C$ on an average. As the inside temperature was lower than the outside one by 7$^{\circ}C$ on an average, we could know that the shading effects of the double- wall greenhouse were excellent in summer daytime.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.337-341
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• 2014

Due to the nature of the ambient air temperature in summer in korea, the growth of crops in greenhouse normally requires cooling and dehumidification. Even though various cooling and dehumidification methods have been presented, there are many obstacles to figure out in practical application such as excessive energy use, cost, and performance. To overcome this problem, the lab scale experiments using lithium bromide(LiBr) solution and cooling coil for dehumidification and cooling in greenhouses were performed. In this study, preliminary experiment of dehumidification and cooling for the greenhouse was done using LiBr solution as the dehumidifying materials, and cooling coil separately and then combined system was tested as well. Hot and humid air was dehumidified from 85% to 70% by passing through a pad soaked with LiBr, and cooled from 308K to 299K through the cooling coil. computational Fluid Dynamics(CFD) analysis and analytical solution were done for the change of air temperature by heat transfer. Simulation results showed that the final air temperature was calculated 299.7K and 299.9K respectively with the deviation of 0.7K comparing the experimental value having good agreement. From this result, LiBr solution with cooling coil system could be applicable in the greenhouse.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.177-184
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• 2009

For the purpose of reducing the cost for greenhouse operation by acquiring the electric power necessary for it, this study installed a solar photovoltaic system on the roof of the building adjacent to green-houses and experimentally examined the quantity of power generation based on weather conditions. The results of the study are as per the below: The maximum, average and minimum temperature while the experiment was conducted was $0.4{\sim}34.1,\;-6.1{\sim}22.2$, and $-14.1{\sim}16.7^{\circ}C$ respectively, and the solar radiation was $28.8MJ{\cdot}m^{-2}$ (maximum), $14.9MJ{\cdot}m^{-2}$ (average), and $0.6MJ{\cdot}m^{-2}$ (minimum). The quantity of electric power didn't increase in proportion to the quantity of solar radiation and instead, it was almost consistent around 750W. Daily maximum, average and minimum consumption of electric power was 5.2kWh, 2.5kWh and 0kWh respectively. Based on the average electric power consumption of the system used for this experiment, it was sufficient in case the capacity and the working time of a hot blast heater are small, but it was short in case they are big. In case the capacity of the hot blast heater is big, the average electric power quantity will be sufficient for array area $21m^2$, about three times of the present area. In summer when the temperature of the array becomes high, the generation of electric power didn't increase in proportion to the quantity of solar radiation, but this experiment result shows a high correlation between two factors (coefficient of correlation 0.84).

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.247-257
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• 2014

The construction of eight large weirs in the Nakdong River, Korea, caused a decrease in the water flow velocity and several physical changes to the water environment. Here, changes in phyto- and zooplankton communities and water quality in the areas near the eight weirs were investigated from 2011 to 2013, and relationships between phytoplankton abundances and environmental factors were analyzed. Special emphasis was given to the succession patterns in algal abundance based on temperature fluctuations. At the eight weirs, 24 dominant species were found. The most abundant phytoplankton species was Stephanodiscus sp. (39.4% of dominant frequency). Cyanobacteria of the genus Microcystis dominated during the summer, with an dominant frequency of 8.5% and cell abundance ratio of 36.6%. Significant correlations were observed between temperature and abundance of eight of the main dominant species; seven species showed positive correlations with temperature. Stephanodiscus sp., however, showed a negative correlation with temperature (r=-0.26, p<0.01). In addition, this species showed a significant negative correlation with the dominant algal species-Aulacoseira granulata and Aphanizomenon flos-aquae, with the zooplankton Copepoda and with Cladocera. On the contrary, seven other dominant species of algae showed significant positive correlations with zooplankton. Thus, we showed that the seasonal succession of plankton communities in the Nakdong River was related to the water temperature changes.

• Korean Journal of Environment and Ecology
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• v.30 no.4
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• pp.724-729
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• 2016

Environmental factors that affect the singing of cicadas have not been studied extensively, especially those affecting the cicadas' singing during the nighttime. Therefore, the objective of this study is to identify the effects of tropical night and light pollution on the cicadas' singing in a downtown area. The study sites were an apartment complex in Seocho-gu, Seoul, and the Chiaksan National Park in Wonju-si. The study subjects were Hyalessa fuscata and Cryptotympana atrata, which are the dominant species in Korea during summer. Cicada songs were recorded 24 hours a day, every day. The recording period was between July and August, lasting 25 days at the Seoul site and 14 days at the Chiaksan National Park. Temperature, precipitation, humidity, and amount of sunshine were selected as the environmental factors that potentially affect the cicadas' singing. Statistical analyses included correlations of meteorological factors with the cicadas' singing per hour, per 24 hours, and at nighttime (21:00~04:00). The results showed that: 1) H. fuscata began singing during the dawn hours, and the singing increased in intensity early in the morning. C. atrata's singing reached its peak in the morning and afternoon, ceased during sunset hours, thereby exhibiting a difference in the singing pattern of the two species. 2) The frequency of singing by H. fuscata decreased when C. atrata began to sing intensively in numbers, thereby exhibiting interspecific influence. 3) The results of the correlation analysis between meteorological factors and the singing of H. fuscata and C. atrata showed that both species tended to sing more when the temperature was higher and sang less on rainy days. 4) When limited to nighttime only, C. atrata showed a tendency of singing when the nighttime temperature was high ($24-30^{\circ}C$, average $27^{\circ}C$), whereas H. fuscata did not show a correlation with meteorological factors. However, since H. fuscata sang during the night in areas with artificial lighting, it was concluded that its singing was due to light pollution.

• Korean Journal of Environment and Ecology
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• v.28 no.2
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• pp.123-127
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• 2014

The red fox (Vulpes vulpes) is currently identified as a restoration target species, because it is listed as level 1 in the Korean National Park Service's endangered species list. The present research was conducted to investigate the basic behavioral patterns distribution of red foxes. For this study, red foxes under semi-natural conditions were observed and recorded from May 2012 to April 2013. The results revealed that the activities of the red foxes began at $16:59{\pm}01:20t$ and ended at an average time of $05:50{\pm}03:02t$. The males began and ended their activities earlier than their female counterparts. Among the seasonal activity durations, the longest activity duration was observed in summer with activity of 14 hours and 5 minutes, while the shortest activity duration was observed in winter with activity periods of 10 hours and 11 minutes. Generally, the red foxes exhibited a nocturnal behavioral pattern; the activity start time of the foxes was influenced by the sunset time. However, the activity end time showed no relationship with the sunrise time. The frequency of daily feeding activity ranged from one to eight times per day, with the males ($2.40{\pm}1.66$) exhibiting higher frequency than their female counterparts ($1.87{\pm}1.24$). The feeding activity peaked in November (average, 3.52 times per day) and was lowest in January (average, 1.28 times per day). Both males and females engaged in daily drinking activity (average, $2.03{\pm}1.296$ times per day). Thus, the increase in the frequency of the feeding activity is related to increase in the frequency of the drinking activity. Although the present research was conducted under semi-natural condition, the findings will be useful for the daily specification management of the species, monitoring of the released foxes, and habitat management based on the behavioral characteristics of the species.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1101-1106
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• 2006

Many BNR (Biological Nutrient Removal) plants have experienced a bulking problem, mainly due to the growth of filamentous organisms, particularly during the winter months. This study investigated the problem of bulking due to the growth of M. parvicella both at a full-scale municipal wastewater treatment plant and a pilot scale plant located in the C city. The full-scale facility was operated at a flow rate of $51,000m^3/d$, an F/M (Food-to-Microorganism) ratio of 0.12 kgBOD/kgMLVSS/d and an SRT (Solids Retention Time) higher than 25 days, respectively. This plant experienced bulking and foaming problems at low temperatures below $15^{\circ}C$ since it was retrofitted with the BNR system in 2003. The pilot plant employed had an identical process configuration as the full scale one and used the same wastewater source. It was operated at a flow rate of $3.8m^3/d$, temperatures between 10 to $25^{\circ}C$ and SRTs between 10 and 25 days. At full scale, the M. parvicella growth and SVI (Sludge Volume Index) patterns were studied in conjunction with temperature variations. At pilot scale, DO and SRT variations were also explored, in addition to the filamentous bacteria growth and SVI patterns. During the full-scale investigation, over a 3 year period, it was noted that the SVI was maintained within acceptable operational values (i.e. under 160) during the summer months. Moreover settling in the secondary clarifiers was good and was not affected by the presence of M. parvicella. In contrast, at low mean temperatures during winter, the SVI increased to over 300. Overall, as the temperature decreased, the predominance of M. parvicella became apparent. According to this study, M. parvicella growth could be controlled and SVI could drop under 160 by a change in operational conditions which involved an increase in DO concentration between 2 and 4 mg/L and a decrease in SRT to less than 20 days.