• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.246-254
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• 2022

Domestic facility agriculture grows rapidly, such as modernization and large-scale. And the production scale increases significantly compared to the area, accounting for about 60% of the total agricultural production. Greenhouses require energy input to create an appropriate environment for stable mass production throughout the year, but the energy load per unit area is large because of low insulation properties. Through the rooftop greenhouse, one of the types of urban agriculture, energy that is not discarded or utilized in the building can be used in the rooftop greenhouse. And the cooling and heating load of the building can be reduced through optimal greenhouse operation. Dynamic energy analysis for various environmental conditions should be preceded for efficient operation of rooftop greenhouses, and about 40% of the solar energy introduced in the greenhouse is energy exchange for crops, so it should be considered essential. A major analysis is needed for each sensible heat and latent heat load by leaf surface temperature and evapotranspiration, dominant in energy flow. Therefore, an experiment was conducted in a rooftop greenhouse located at the Korea Institute of Machinery and Materials to analyze the energy exchange according to the growth stage of crops. A micro-meteorological and nutrient solution environment and growth survey were conducted around the crops. Finally, a regression model of leaf temperature and evapotranspiration according to the growth stage of leafy vegetables was developed, and using this, the dynamic energy model of the rooftop greenhouse considering heat transfer between crops and the surrounding air can be analyzed.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.216-237
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• 2017

Thermal effluent of the hot spring has long been a field of interest in the relationship between temperature gradient and freshwater algae in geology, limnology and aquatic ecology throughout the world. On the other hand, many artificial hot springs have been developed in Korea, but the research on them has not been still active. This study was performed every month from December 2015 to September 2016, to elucidate the spatiotemporal effects of thermal wastewater effluent (TWE) on the ecosystem of benthic algal assemblage in four stations(BSU (upstream), HSW (hot spring wastewater outlet), BSD1~2 (downstream)) of the upstream reach of the Buso Stream, a tributary located in the Hantan River basin. During the survey, the influencing distance of temperature on TWE was <1.0 km, and it was the main source of N P nutrients at the same time. The effects of TWE were dominant at low temperature and dry season (December~March), but it was weak at high temperature and wet season (July~September), reflecting some seasonal characteristics. Under these circumstances, the attached algal communities were identified to 59 genera and 143 species. Of these, the major phylum included 21 genera 83 species of diatoms(58.0%), 9 genera 21 species of blue-green algae (14.7%) and 25 genera 32 species of green algae (22.4%), respectively. The spatiotemporal distribution of them was closely related to water temperature ($5^{\circ}C$ and $15^{\circ}C$) and current ($0.2m\;s^{-1}$ and $0.8m\;s^{-1}$). In the basic environment maintaining a high water temperature throughout the year round, the flora favoring high affinity to $PO_4$ in the water body or preferring stream habitat of abundant $NO_3-PO_4$ was dominant. As a result, when compared with the outcomes of previous algal ecology studies conducted in Korea, the Buso Stream was evaluated as a serious polluted state due to persistent excess nutrient supply and high thermal pollution throughout the year round by TWE. It can be regarded as a dynamic ecosystem in which homogeneity (Summer~Autumn) and heterogeneity (Winter~Spring) are repeated between upstream and downstream.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.121-132
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• 2005

We investigated the reproductive cycle with gonad developmental phases of Sinonovacula constricta by histological observations, and seasonal changes in biochemical component of the adductor muscle, visceral mass, foot muscle and mantle were studied by biochemical analysis, from January to December, 2004. The reproductive cycle of this species can be classifed into five successive stages: early active stage (March to May), late active stage (May to July), ripe stage (July to September), partially spawned stage (August to October) and spentfinactive stage (October to March). Total protein content was the highest in the following order: adductor muscle, visceral mass, foot muscle, and mantle. Except for mantle, it was generally higher during the ripe and spawning stages, while lower during the spent/inactive stage. There were positive correlations in total protein contents among adductor muscle, foot muscle, and visceral mass. However, the correlations were not statistically significant. Total lipid content was the highest in the visceral mass; it was more than 5 or 6-fold higher than those in the adductor muscle, foot muscle, or mantle. The monthly change was also most dynamic in the visceral mass. It first Increased during the early active stage (March to May), decreased during late active stage (May to July), and then increased again rapidly during the spawning stage (September). There were a strong negative correlation in total lipid contents between foot muscle and adductor muscle (r = -0.634, p = 0.027), and a strong positive correlation between adductor muscle and mantle (r = 0.665, p = 0.018). Glycogen contents showed more or less similar pattern to total lipid contents in the adductor muscle, foot muscle, and visceral mass. It was higher during the early active and spawning stages, while lower during the late active and spent/inactive stages. There was no statistically significant correlation in glycogen contents among different tissues. Especially, total lipid content showed a negative correlationship between the foot muscle, adductor muscle, visceral mass and mantle. Therefore, these results indicate that the nutrient content of the foot muscle, adductor muscle, viseral mass and mantle changed in response to gonadal energy needs.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.348-359
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• 2008

The objectives of the study were to elucidate functional modifications in relation to hydrological, physico-chemical and ecological aspects in Daechung Reservoir by the upper dam constructions of Youngdam Reservoir and analyze temporal and spatial dynamic patterns using trophic parameters of TN, TP, chlorophyll (CHL), and Secchi depth (SD). Hydrological data such as inflow, precipitation, and water levels before (BDC, 1995$\sim$2000) and after (ADC, 2001$\sim$2006) the dam construction showed that precipitation had greater correlations with inflow volume in the BDC (r=0.964, p=0.002) than in the ADC (r=0.857, p=0.029). This outcome indicates that the upper dam construction influenced the inflow and water level of Daechung Reservoir. One of the greatest changes after the dam construction was decreases of nutrient contents (TN, TP) and increases of algal biomass (as CHL) as the water residence time increases. Values of CHL had greater relations with TP in the ADC (r=0.412, p<0.001) than the BDC (r=0.249, p<0.001), indicating that CHL had greater response at a given phosphorus in the ADC. Thus, algal yield at a given TP (CHL : TP ratios) increased in the ADC, resulting in a greater CHL-TP relations. Long-term interannual TP, TN, SD, and CHL showed greater variations in the riverine zone (RZ) than any other transition (TZ) and lacustrine zones (LZ). This phenomenon was mainly attributed to rapid hydrological response in the riverine zone (RZ) to flow reductions (short water residence time) from the upper dam, resulting in ambient contents of nutrients and light regime along with functional relations of CHL-TP.

• The Korean Journal of Malacology
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• v.20 no.2
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• pp.111-120
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• 2004

We investigated the reproductive cycle of Corbicula japonica with its gonadal development by histological observations, and the seasonal changes in biochemical mass and foot muscle of the adductor muscle, visceral mass and foot muscle of the clam by biochemical analysis, from January to December, 2003. The reproductive cycle of this species can be classified into five successive stages: early active stage (February to April), late active stage (April to July), ripe stage (June to August), partially spawned stage (July to September) and spent/inactive stage (September to March). According to ANOVA test, there were significant differences (p < 0.05) in total protein, total lipid and glycogen contents among months for all of the visceral mass, adductor muscle and foot muscle. Total protein content was highest in adductor muscle, while lowest in visceral mass. There was no correlation in total protein content between visceral mass and adductor muscle (p = 0.208). However, strong positive correlation was found between adductor muscle and foot muscle (r = 0.769, p < 0.001). In visceral mass, total lipid content was the highest; it was 2 or 3-fold higher than in adductor muscle or foot muscle. The monthly change was also most dynamic in visceral mass. It decreased from January to March (early active stage), and reached maximum in April (late active stage). From May to August (ripe and partially spawned stage), it dradually decreased and then increased again until October (spent/inactive stage). Multiple comparisons showed that total lipid content in visceral mass between all of the adjacent two months was significaltly different (p < 0.05). There were strong negative correlations in total lipid content between visceral mass and adductor muscle (r = 0.687, p < 0.001), and between visceral mass and foot muscle (r = 0.473, p = 0.008). Changes of glycogen content were more or less similar to the changes of lipid contents in visceral mass, adductor muscle and foot muscle, except for April. In April, glycogen content in visceral mass was over four times higher than that in adductor muscle or foot muscle. There was a positive correlation in glycogen content between adductor muscle and foot muscle (r = 0.686, p < 0.001). Especially, total lipid content showed a negative correlation between the adductor muscle and visceral mass. Therefore, these results indicate that the nutrient content of the adductor muscle, visceral muscle and foot muscle changed in response to gonadal energy needs.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.160-171
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• 2002

The impact of summer monsoon on water quality of the lower Nakdong River was evaluated during the summer (June-August) in 1997. Several limnological variables were measured in the interval of $1{\sim}3$ day using an automatic monitoring system (Hydrolab $Recorder^{TM}$) to detect water quality changes caused by rainfall on onehour basis. During the monsoon period (from late June to mid July), 5 times of major rainfall events of >50 mm were recorded in the river basin. Dynamic changes of water quality were observed during the monsoon, and the first rainfall event (June$25{\sim}27$) had a significant influence on the water quality at the lower part of the river. All Parameters were largely changed due to the first rain event, and the changed level was maintained until the end of monsoon period. Nutrient concentrations and turbidity increased and values of the other parameters were declined as a result of water dilution. This rainfall event, Changma, is a meteorological phenomenon caused by the East-Asian monsoon climate. The magnitude and frequency of the rainfall during the early monsoon play an important role in change of water quality and ecosystem characteristics of large river systems.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.295-303
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• 2018

Inland wetlands in the Republic of Korea provide key breeding and wintering habitats, while coastal wetlands provide nutrient-rich habitats for stopover sites for East Asia/Australasia Flyway(EAAF) migrants. However, since the 1960's, Korea has reclaimed these coastal wetlands gradually for agriculture and urban expansion. The habitat loss has rippled across global populations of migrant shorebirds in EAAF. To protect a similar loss, the United States, specifically Missouri, developed the moist-soil management technique. Wetland impoundments are constructed from levees with water-flow control gates with specific soils, topography, available water sources, and target goals. The impoundments are subjected to a combination of carefully timed and regulated flooding and drawdown regimes with occasional soil disturbance. This serves a dual purpose of removing undesirable vegetation, while maximizing habitat and forage for wildlife. Flooding and drawdown schedules must be dynamic with constantly shifting climate conditions. Korea's latitude ($N33^{\circ}25^{\prime}{\sim}N38^{\circ}37^{\prime}$) is comparable to Missouri ($N36^{\circ}69^{\prime}{\sim}N40^{\circ}41^{\prime}$); as such, moist-soil management could prove to be an effective wetland restoration technique for Korea. In order to meet specific conservation goals (i.e. shorebird staging site restoration), it is necessary to test the proposed methodology on a site that can meet the required specifications for moist-soil management. Moist-soil management has the potential to not only create key habitat for endangered wildlife, but also provide valuable ecosystem services, including water filtration.