• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.4
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• pp.449-454
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• 2022

The oxygen consumption rate (OCR) based on the water temperature and body size of the sea squirt Halocynthia roretzi was examined to provide quantitative information about the metabolic response of the species. OCRs were measured using a closed flow-through respirometer at four different water temperatures (10, 15, 20 and 25℃) and two different body sizes (21.4±1.1 g and 150.5±1.3 g, wet weight) with triplicates of each treatment. OCR increased as water temperature increased at both body sizes, but decreased as body size increased regardless of the water temperature (P<0.001). The effect of body size evaluated as a power function ranged from 0.8055 to 0.8884. The highest Q₁₀ values in the small and large size groups ranged from 15 to 20℃ and 20 to 25℃, respectively. The metabolic daily energy loss rate via respiration at all tested temperatures ranged from 56.2 to 106.1 J g^-1 d^-1 in the small-size group and from 44.5 to 92.0 J g^-1 d^-1 in the large-size group. Our results indicate that the metabolic response of H. roretzi highly depends on fluctuating water temperature at a given life stage.

• Korean Journal of Environmental Agriculture
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• v.41 no.1
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• pp.32-40
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• 2022

BACKGROUND: Climate-smart agriculture (CSA) has been proposed for sustainable agriculture and food security in an agricultural ecosystem disturbed by climate change. However, scientific approaches to local agricultural ecosystems to realize CSA are rare. This study attempted to evaluate the weather condition, rice production, and greenhouse gas emissions from the rice cultivation in Hwaseong-si, Gyeonggi-do to fulfill CSA of the rice cultivation. METHODS AND RESULTS: Over the past 3 years (2017~2019), Chucheong rice cultivar yield and methane emissions were analyzed from the rice field plot (37°13'15"N, 127° 02'22"E) in the Gyeonggi-do Agricultural Research and Extension Services located in Gisan-dong, Hwaseong-si, Gyeonggi-do. Methane samples were collected from three automated closed chambers installed in the plot. The weather data measured through automatic weather station located in near the plot were analyzed. CONCLUSION(S): The rice productivity was found to vary with weather environment in the agricultural ecosystem. And methane emissions are high in a favorable weather condition for rice growth. Therefore, it is necessary to minimize the trade-off between the greenhouse gas emission target for climate change mitigation and productivity improvement for CSA in a local rice cultivation.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.19-34
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• 2022

This study was identified the distribution of vegetation in domestic estuaries and analysed the relationship with environmental fcators based on the health assessment data of the estuary ecosystem surveyed between 2016 and 2018. Of the 325 estuaries surveyed, 187 vegetation communites were investigated in 300 estuaries and 53 halophyte communites accounted for 28.3%. No vegetation distribution was found in the other 25 estuaries. Considering the circulation of estuary, 41 halophyte communites were investigated in open estuaries and 26 halophyte communites in closed estuaries. As a result of canonical correlation analysis (CCA) between the entire distributed vegetation community and environmental factors, salinity (conductivity), T-N, and T-P concentrations were strongly correlated. Among the riverbed material materials of the estuary, the composition ratio of silt, sand, and pebble was the most correlated. Therefor, it is estimated that the distribution location of the halophyte communites were differentiated by being influenced by the sea ares, estuary circulation type, resistance to salinity and riverbed material ratio.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.4
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• pp.176-184
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• 2011

Cold air on sloping surfaces flows down to the valley bottom in mountainous terrain at calm and clear nights. Based on the assumption that the cold air flow may be the same as the water flow, current models estimate temperature drop by regarding the cold air accumulation at a given location as the water-like free drainage. At a closed catchment whose outlet is blocked by man-made obstacles such as banks and roads, however, the water-like free drainage assumption is no longer valid because the cold air accumulates from the bottom first. We developed an empirical model to estimate quantitatively the effect of cold pool on nocturnal temperature in a closed catchment. In our model, a closed catchment is treated like a "vessel", and a digital elevation model (DEM) was used to calculate the maximum capacity of the cold pool formed in a closed catchment. We introduce a topographical variable named "shape factor", which is the ratio of the cold air accumulation potential across the whole catchment area to the maximum capacity of the cold pool to describe the relative size of temperature drop at a wider range of catchment shapes. The shape factor is then used to simulate the density profile of cold pool formed in a given catchment based on a hypsometric equation. The cold lake module was incorporated with the existing model (i.e., Chung et al., 2006), generating a new model and predicting distribution of minimum temperature over closed catchments. We applied this model to Akyang valley (i.e., a typical closed catchment of 53 $km^2$ area) in the southern skirt of Mt. Jiri National Park where 12 automated weather stations (AWS) are operational. The performance of the model was evaluated based on the feasibility of delineating the temperature pattern accurately at cold pool forming at night. Overall, the model's ability of simulating the spatial pattern of lower temperature were improved especially at the valley bottom, showing a similar pattern of the estimated temperature with that of thermal images obtained across the valley at dawn (0520 to 0600 local standard time) of 17 May 2011. Error in temperature estimation, calculated with the root mean square error using the 10 low-lying AWSs, was substantially decreased from $1.30^{\circ}C$ with the existing model to $0.71^{\circ}C$ with the new model. These results suggest the feasibility of the new method in predicting the site-specific freeze and frost warning at a closed catchment.

• Journal of Korean Society of Forest Science
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• v.96 no.2
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• pp.227-234
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• 2007

The forest canopy gap has been well known as a substantial process of forest cyclic regeneration and important role in stand structure, dynamics, and biodiversity of the forest ecosystem. Based on 3,600 $5m{\times}5m$ square grids in a 9ha permanent experimental plot, the study was conducted to evaluate the regeneration pattern of woody species by developmental stage {seedlings (<1 m of height), saplingI (>1 m of height, <2 cm of DBH), and saplingII (2 cm$<200m^2$), $201-400m^2$, $400-600m^2$, $601-800m^2$, and $>800m^2$) in the mixed broadleaved-Korean pine forest. The results indicated that the regenerating trees of Populus ussuriensis occurred only in the canopy gap area, considered to be a typical gap-dependent species. The regeneration of Ulmus japonica, Ulmus laciniata, and Maackia amurensis could be generally satisfied with the gap size of $201-600m^2$, Betula costata and Prunus padus with gap size of $401-800m^2$, Picea koraiensis with gap size of $201-800m^2$, Fraxinus mandshurica and Syringa reticulata var. mandshurica with smaller than $800m^2$, respectively. Acer ukurunduense and Acer tegmentosum were likely to have no problem with the gap size to make gap regeneration. Acer mono and Tilia amurensis looked more capable of regenerating in the closed canopy disregarding the upper crown condition. The regeneration of Pinus koraiensis and Abies nephrolepis had no trouble under the canopy condition in less than $800m^2$of gap size. The density of regenerating shrubs was rather high, especially under the closed canopy, considered to be associated with great amount of regeneration production in such shade tolerant species as Lonicera maackii, Corylus mandshurica, Euonymus pauciflorus, and Philadelphus schrenkii under the closed canopy. Pearson correlation coefficient was computed to compare the similarity among non-gap area and five gap size classes by developmental stages for trees and shrubs. The similarity coefficients among closed canopy and the gap size classes were mostly significantly correlated to each other with a few exceptions.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.187-196
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• 2012

Recently, for the purpose of constructing artificial ecosystem, the public aquarium and experimental mesocosm systems are receiving attention. To design and establish an aquarium and mesocosm system, there is need of several materials for simulating the environment, such as sediments, rocks, and plants. Expecially for sessile mollusks, there must be proper materials to which sessile invertebrates can adhere. Nowadays, many aquariums and mesocosm systems are using dead coral skeletons for sessile mollusks. This study was proceeded to have data on the effect of dead coral skeletons on water qualities with the experiment on the environmental factors. For this purpose, I made glass tank for experiment, chose two types of dead coral skeletons imported from the Indonesia and observed the change of water qualities and decomposition efficiency of TAN (total ammonia-nitrogen), nitrite ($NO_2{^-}$) and nitrate ($NO_3{^-}$). As a result, the lager the surface area was, the more TAN, nitrite and nitrate decomposition rate increased. In addition, coral skeletons covered with crustose algae and bacteria in the tank showed faster TAN, nitrite and nitrate removal rate and stabilization. Accordingly, this experiment suggested that dead coral skeletons could be used as a sub filter for the closed system as well as an adhering plate.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.2
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• pp.94-100
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• 2003

Soil $CO_2$ emission is one of the primary components in carbon balance of terrestrial ecosystems. To accurately assess their net ecosystem exchange of $CO_2$ and net primary production, measurement of soil $CO_2$ efflux is required along with that of canopy $CO_2$ flux. In this paper, soil $CO_2$ flux measurement technique using closed dynamic chamber systems is briefly reviewed. Preliminary results on soil $CO_2$ exchange and inter-comparison of different measurement systems currently used in Korean regional network of tower flux measurement sites (KoFlux) are also reported.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.152-159
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• 1996

Experiment was performed in a newly developed wind tunnel with light system to determine the aerodynamic resistance and eddy diffusivity above the plug stand under artificial light. Maximum air temperature appeared near the top of the plug stand under artificial light. Since Richardson number was ranged from -0.07 to +0.01, the atmosphere above the plug stand in wind tunnel was in an unstable or near- neutral stability state. The average aerodynamic resistance at rear region of plug stand was 25 % higher than that at middle region. Eddy diffusivity($K_{M}$) linearly increased with the increasing air current speed. $K_{M}$ at air current speed of 0.9 m.$s^{-1}$ was about two times as many as that at air current speed of 0.3 m.$s^{-1}$. And average $K_{M}$ at the rear region was 15% lower than that at the middle region. These results indicated that the diffusion of heat and mass along the direction of air current inside the plug stand was different. It might cause the lack of uniformity in the growth and quality of plug seedlings. The wind tunnel developed in this study would be useful to investigate the effects of air current speed on microclimates and the growth of plug seedlings under artificial light in a semi- closed ecosystem.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.2
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• pp.95-100
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• 2010

In this study we predicted some of the negative effects on the ocean ecosystem and water quality, caused by a coastal reclamation project in semi-closed bay that makes it extremely difficult to be purified by natural process. In order to predict change of water quality triggered by coastal reclamation, the 3D hydrodynamic model and material cycle model are used. And we suggested new ecological park, an artificial beach and eco-friendly revetments on the reclamation area to mitigate the environmental impacts affecting this area using the numerical simulation results and observation data.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.2
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• pp.239-261
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• 1998

This thesis is concerned with international fisheries cooperation among Korea, China and Japan in the Yellow sea and the East China sea. For this purpose, considerated international fisheries problems relation with these countries refer to literature. Specially adjusted the focus founding of necessity and methods about international fisheries cooperation among these countries. The conclusion is as followed; At first, these countries necessity required international fisheries cooperation because of following reasons. 1. These countries have legal duties for conservation and utilization of marine living resources according to united nations convention law of the sea. 2. These countries that jointly owned semi-closed sea have legal duties for cooperation in respect of fisheries and environment problems. 3. These countries belongs to a same ecosystem and shared with staddling stocks in the Yellow sea and the East china sea. The Second, these countries certainly required international fisheries cooperation following methods. 1. These countries must establish marine area for joint control of marine living resources. 2. These countries must establish tentatively named "International fisheries cooperation body" for deal with comprehensive problems about fisheries.