• Journal of Aquaculture
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• v.12 no.3
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• pp.247-254
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• 1999

Changes of oxygen consumption of Nile tilapia in relation to different body sizes(average body weight 4 g, 40 g, 120 g and 400 g) and water temperatures ($20^{\circ}C$, $25^{\circ}C$ and $30^{\circ}C$) were investigated by a continuous oxygen monitoring system. Mean oxygen consumption of 4 g, 40 g, 120 g and 400 g Nile tilapia at $20^{\circ}C$ were 318.8, 214.9, 84.1 and 69.4 mg $O_2$/kg fish/hr and that at $25^{\circ}C$ were 435.2, 345.9, 151.5 and 115.9 mg $O_2$/kg fish/hr, and that at $30^{\circ}C$ were 611.1, 538.4, 320.8, and 236.0 mg $O_2$/kg fish/hr, respectively. Oxygen consumption per unit body weight tended to decrease exponentially at all temperatures (P<0.05) as body weigth of the fish increased. Oxygen consumption of this fish at $25^{\circ}C$ was $1.61\pm0.18$ times higher than that at $20^{\circ}C$ and oxygen consumption at $30^{\circ}C$ was $1.53\pm0.27$ times higher than that at $25^{\circ}C$. Oxygen consumption per unit body weight linearly increased with the water temperature increased. Also, oxygen consumption of this fish during day time was higher than that during night time at 12L:12D day light condition. The differences between maximum and minimum daily oxygen consumption of this fish increased with the water temperature increased.

• Journal of Environmental Science International
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• v.18 no.1
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• pp.33-39
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• 2009

Based on the monthly weather report of Korea Meteorological Administration (KMA) and daily sea surface temperature (SST) data from National Fisheries Research and Development Institute (NFRDI) in 2006, heat budget was estimated at Gampo in the eastern coast of Korea, the region occuring the cold water known as upwelling in summer. Net heat flux was transported from the air to the sea surface during February to November, and it amounts to $345Wm^{-2}$ in monthly mean value. During December to January, the transfer of net heat flux was conversed from the sea surface to the air with $-56Wm^{-2}$ in minimum of monthly mean value in January. Long wave radiation was ranged from $6Wm^{-2}\;to\;106Wm^{-2}$. Sensible heat was varied from $-36Wm^{-2}$(June) to $61Wm^{-2}$(February) and showed negative values from April to August. Latent heat showed $20Wm^{-2}$(July) with its minimum in July and $49Wm^{-2}$ with its maximum in March in monthly mean value. The annual mean of net heat flux is $129Wm^{-2}$, giving an annual heat surplus of $22Wm^{-2}$. Thus, during summer, the upwelled cold water at Gampo, appears to compensate the heat gain. However the ways in which these compensations are accomplished remains to be clarified.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.132-137
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• 1993

Some biological characteristics with respect to tuber formation of Eleocharis kuroguwai Ohwi were investigated. Tuber formation was initiated at the descending time of daily maximum and minimum temperatures, accelerated under the minimum temperature lower than $20^{\circ}C$, and terminated at about $10^{\circ}C$. Tubers produced at the early season were located at deeper soil layers. Large tubers were found at deeper soil depths and required the longer period for sprouting as compared with small tubers. Percent emergence decreased as the emergence depth increased, while percent old-tuber produced during previous years was greater at the deeper depths.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.250-260
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• 2013

The annual and monthly fluctuation in the species composition and the catch abundance of dominant species were analyzed using the daily sales slip catch data by a set net in the offshore waters off Dolsan Island in Yeosu from March 2004 to December 2011. Mean catch from 2004 to 2011 is 372M/T and the maximum and the minimum catch are 526 M/T in 2005 and 27 2M/T in 2009, respectively. The dominant species were Engraulis japonicus mainly in spring and Scomberomorous niphonius in Autumn and therefore the set net catch that is dominated by S. niphonius's catch was much higher in autumn than in spring. Through comparative analyses for the environmental factors to the annual catch fluctuation, it is revealed that the water temperature variation affected the recruitment property of S. niphonius to the fishing ground but the effect of typhoon on the catch fluctuation was not distinct. Furthermore, the big blooming event of jellyfish, particularly Nemopilema nomurai, that occurred in 2009 showed a tendency of faster appearance and later extinction until December. The occurring characteristic of N. nomurai became a direct cause that brought about the lowest total catch in 2009 since the dominant species catch of the set net fishery was concentrated mostly in Autumn.

• The Plant Pathology Journal
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• v.36 no.1
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• pp.54-66
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• 2020

This study was conducted to evaluate usefulness of numerical weather prediction data generated by the Unified Model (UM) for plant disease forecast. Using the UM06- and UM18-predicted weather data, which were released at 0600 and 1800 Universal Time Coordinated (UTC), respectively, by the Korea Meteorological Administration (KMA), disease forecast on bacterial grain rot (BGR) of rice was examined as compared with the model output based on the automated weather stations (AWS)-observed weather data. We analyzed performance of BGRcast based on the UM-predicted and the AWS-observed daily minimum temperature and average relative humidity in 2014 and 2015 from 29 locations representing major rice growing areas in Korea using regression analysis and two-way contingency table analysis. Temporal changes in weather conduciveness at two locations in 2014 were also analyzed with regard to daily weather conduciveness (C_i) and the 20-day and 7-day moving averages of C_i for the inoculum build-up phase (C_inc) prior to the panicle emergence of rice plants and the infection phase (C_inf) during the heading stage of rice plants, respectively. Based on C_inc and C_inf, we were able to obtain the same disease warnings at all locations regardless of the sources of weather data. In conclusion, the numerical weather prediction data from KMA could be reliable to apply as input data for plant disease forecast models. Weather prediction data would facilitate applications of weather-driven disease models for better disease management. Crop growers would have better options for disease control including both protective and curative measures when weather prediction data are used for disease warning.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.1
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• pp.37-43
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• 2001

Crop status monitoring and yield prediction at higher spatial resolution is a valuable tool in various decision making processes including agricultural policy making by the national and local governments. A prototype crop forecasting system was developed to project the size of rice crop across geographic areas nationwide, based on daily weather pattern. The system consists of crop models and the input data for 1,455 cultivation zone units (the smallest administrative unit of local government in South Korea called "Myun") making up the coterminous South Korea. CERES-rice, a rice crop growth simulation model, was tuned to have genetic characteristics pertinent to domestic cultivars. Daily maximum/minimum temperature, solar radiation, and precipitation surface on 1km by 1km grid spacing were prepared by a spatial interpolation of 63 point observations from the Korea Meteorological Administration network. Spatial mean weather data were derived for each Myun and transformed to the model input format. Soil characteristics and management information at each Myun were available from the Rural Development Administration. The system was applied to the forecasting of national rice production for the recent 3 years (1997 to 1999). The model was run with the past weather data as of September 15 each year, which is about a month earlier than the actual harvest date. Simulated yields of 1,455 Myuns were grouped into 162 counties by acreage-weighted summation to enable the validation, since the official production statistics from the Ministry of Agriculture and Forestry is on the county basis. Forecast yields were less sensitive to the changes in annual climate than the reported yields and there was a relatively weak correlation between the forecast and the reported yields. However, the projected size of rice crop at each county, which was obtained by multiplication of the mean yield with the acreage, was close to the reported production with the $r^2$ values higher than 0.97 in all three years.

• Journal of Climate Change Research
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• v.9 no.2
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• pp.157-169
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• 2018

This study explores the long?term trends of extreme temperatures of 270 observation stations in East Asia (China, Japan, and Korea) for 1961?2013. The 5th percentile of daily minimum temperatures (TN05%) and 95th percentile of daily maximum temperatures (TX95%), derived from the quantile regression, are particularly examined in term of their linear and nonlinear trends. The warming trends of TN05% are typically stronger than those of TX95% with more significant trends in winter than in summer for most stations. In both seasons, warming trends of TN05% tend to amplify with latitudes. The nonlinear trends, quantified by the $2^{nd}$?order polynomial fitting, exhibit different structures with seasons. While summer TN05% and TX95% were accelerated in time, winter TN05% underwent weakening of warming since the 2000s. These results suggest that extreme temperature trends in East Asia are not homogeneous in time and space.

• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.352-362
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• 2022

Photosynthesis and respiration of seagrasses are mainly controlled by water temperature. In this study, the photosynthetic physiology and respiratory changes of the Asian surfgrass Phyllospadix japonicus, which is mainly distributed on the eastern and southern coasts of Korea, were investigated in response to changing water temperature (5, 10, 15, 20, 25, and 30℃) by conducting mesocosm experiments. Photosynthetic parameters (maximum photosynthetic rate, P_max; compensation irradiance, I_c; and saturation irradiance, I_k) and respiration rate of surfgrass increased with rising water temperature, whereas photosynthetic efficiency (α) was fairly constant among the water temperature conditions. The P_max and I_k dramatically decreased under the highest water temperature condition (30℃), whereas the I_c and respiration rate increased continuously with the increasing water temperature. Ratios of maximum photosynthetic rates to respiration rates (P_max : R) were highest at 5℃ and declined markedly at higher temperatures with the lowest ratio at 30℃. The minimum requirement of H_sat (the daily period of irradiance-saturated photosynthesis) of P. japonicus was 2.5 hours at 5℃ and 10.6 hours at 30℃ for the positive carbon balance. Because longer H_sat was required for the positive carbon balance of P. japonicus under the increased water temperature, the rising water temperature should have negatively affected the growth, distribution, and survival of P. japonicus on the coast of Korea. Since the temperature in the temperate coastal waters is rising gradually due to global warming, the results of this study could provide insights into surfgrass responses to future severe sea warming and light attenuation.

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1589-1595
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• 2016

From December 2014 to November 2015, an automatic weather system (AWS) was installed over a wide road of Daegu to continuously measure meteorological factors and surface temperature. We investigated the effective operating period of the clean-road system using the daily maximum and minimum air and asphalt surface temperatures, with the aim of creating an optimum thermal environment. The clean-road system was installed over a part of the broad way of Dalgubul(Dalgubul-Daero) by Daegu Metropolitan City in 2011. Until now, the clean-road system has been operated from the middle of April to the end of September. We assumed that it was desirable that the clean-road system could be operated when the discomfort index was above 55. In conformity with the conditions, we concluded that the optimum operation period of the clean-road system is from the end of March to about the middle of October.

• The Korean Journal of Ecology
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• v.21 no.1
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• pp.89-96
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• 1998

The diurnal changes of the stomatal conductance, transpiration and leaf water potential were measured in order to assess the water relations characteristics of Pueraria thunbergiana in August of 1995 and 1996. The results showed two different responses depending on the duration of rainless days. The microclimatic conditions were highly stressful on 2 August. Daily maximum temperature reached to $39.0{\circ}C$ and vapor pressure deficit was 3.55 KPa. During this time the leaf water potential decreased to -1.02 MPa and a marked reduction of stomatal conductance was shown. However, on 15 August the stomatal conductance increased with increment of photon flux density, and transpiration was highly maintained during the day time. Minimum leaf water potential was only -0.47 MPa in spite of high transpiration rate. Furthermore, on 15 August reduced leaf water potential during the day time was recovered rapidly with decrease of photon flux density, whereas recovery of leaf water potential on 2 August was delayed. However, reduced leaf water potential on 2 August was recovered untile the next dawn. Osmotic potential at turgor loss point of Pueraria thunbergiana on 2, 3 and 15 August was -1.79, -1.70 and -1.60 MPa, respectively. The vapor pressure deficit is more contributive to the regulation of stomatal conductance than leaf water potential.