• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.323-328
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• 2003

This study deals with the relationship between the red tide occurrence and the meteorological and marine factors, the prediction of areas where the red tide is likely to occur based on the information, and the satellite monitoring for the red tide in mid-South Sea of Korea. From 1990 to 2001, the red tide was observed every year and the number of occurrences increased as well. The red tide mostly occurred in July, August, and September. The most important meteorological factor governing the mechanisms of the increase in the number of red tide occurrences is found to be a heavy precipitation. It was found that the favorable marine environmental conditions for the red tide formation are some of marine factors such as the warm water temperature, the low salinity, the high suspended solid, the low phosphorus, and the low nitrogen. The necessary conditions for the red tide occurrence are found to be the heavy precipitation (23.4∼54.5 mm) for 2∼4 days, the warm temperature (24.64-25.85 $^{\circ}C$), proper sunshine (2∼10.3 h), and light winds (2∼4.6 m/s & SW) for the day in red tide occurrence. It was possible to monitor the spatial distributions and concentration of the red tide using the satellite images. It was found from this study that the likely areas for red tide occurrence in August 2000 were Yosu ∼ Dolsan coast, Gamak bay, Namhae coast, Marado coast, Goheung coast, and Deukryang bay.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.213-220
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• 2000

Grafting of fruit-bearing vegetables has been widely used to increase the resistance to soil-borne diseases, to increase the tolerance to low temperature or to soil salinity, to increase the plant vigor, and to extend the duration of economic harvest time. After grafting, it is important to control the environment around grafted seedlings for the robust joining of a scion and rootstock. Usually the shading materials and plastic films are used to keep the high relative humidity and low light intensity in greenhouse or tunnel. It is quite difficult to optimally control the environment for healing and acclimation of grafted seedlings under natural light. So the farmers or growers rely on their experience for the production of grafted seedling with high quality. If artificial light is used as a lighting source for graft-taking of grafted seedlings, the light intensity and photoperiod can be easily controlled. The purpose of this study was to develop a prototype system for the graft-taking enhancement of grafted seedlings using artificial lighting and to investigate the effect of air current speed on the distribution of air temperature and relative humidity in a graft-taking enhancement system. A prototype graft-taking system was consisted by polyurethane panels, air-conditioning unit, system controller and lighting unit. Three band fluorescent lamps (FL20SEX-D/18, Kumho Electric, Inc.) were used as a lighting source. Anemometer (Climomaster 6521, KANOMAX), T-type thermocouples and humidity sensors (CHS-UPS, TDK) were used to measure the air current speed, air temperature and relative humidity in a graft-taking system. In this system, air flow acted as a driving force for the diffusion of heat and water vapor. Air current speed, air temperature and relative humidity controlled by a programmable logic controller (UP750, Yokogawa Electric Co) and an inverter (MOSCON-G3, SAMSUNG) had an even distribution. Distribution of air temperature and relative humidity in a graft-taking enhancement system was fairly affected by air current speed. Air current speed higher than 0.1m/s was required to obtain the even distribution of environmental factors in this system. At low air current speed of 0.1m/s, the evapotranspiration rate of grafted seedlings would be suppressed and thus graft-taking would be enhanced. This system could be used to investigate the effects of air temperature, relative humidity, air current speed and light intensity on the evaportranspiration rate of grafted seedlings.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.2
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• pp.71-78
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• 2012

Eupatilin, one of representative medical components of mugwort, can be efficiently extracted from the 'Gangwha Sajabalssuk'. The Eupatilin content may depend on environmental factors such as soil and regional climate in addition to a genetic factor and Gangwha region has a profitable environmental condition for the mugwort growth. In this study, the climatological characteristics of Gangwha was analyzed in order to find the environmental condition of mugwort containing high Eupatilin in term of atmospheric, oceanographic and land variables. The climate of Gangwha is characterized by the relatively low daily temperature and large diurnal variation with plenty of solar radiation, long sunshine duration and less cloudiness. According to our correlation analysis, the long sunshine duration and the large diurnal temperature variation are highly correlated with the Eupatilin contents. The result implies that Gangwha has the favorable conditions for the cultivation and the habitat of the high-Eupatilin concentrated mugwort. Because of the sea surrounding Gangwha Island with low salinity and moderate wind, the salt contained in sea breeze is relatively low compared to other regions. Furthermore, Gangwha has clean atmospheric environment compared to other regions because the concentrations of toxic gases harmful to crop growth such as nitrogen dioxide ($NO_2$), sulfite gas ($SO_2$) and fine dust (PM-10) are lower in the air. The ozone ($O_3$) concentration is moderate and within the level of natural production. It is also found that moderately coarse texture or fine loamy soils known as good for water drainage and for the growth and cultivation of the 'Gangwha-mugwort' are distributed throughout the areas around mountainous districts in Gangwha, coinciding with those of mugwort habitat.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.129-139
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• 2002

We investigated the outbreak of red tides dominated by harmful dinoflagellates from August to November 1999 in the coastal waters off the southern Saemankeum areas where a huge red tide dominated by Cochlodinium polykrikoides had been first observed in 1998. We took water samples from 2~5 depths of 4 stations (with 3-4 additional stations during red tides) in this study period and then measured the abundance of phytoplankton, water temperature, salinity, and the concentrations of nutrients. In the study period harmful dinoflagellates Alexandrium tamarense, C. polykrikoides, Gymnodnium catenatum, Gyrodinium aureolum, Gymnodnium impudicum were present, and of these G. aureolum and C. polykrikoides formed red tide patches on September 16 and October 18, respectively. The date of the outbreak of red tide dominated by C. polykrikoides in the study area was approximately 50 days later than that off the Kohung areas in 1997 and the surface water temperature when the red tides outbroke in the former area was 6$^{\circ}C$ lower than that fur the latter area. The maximum abundance of C. polykrikoides on September 16, October 7 and 18 were 5, 14, and 463 cells $m\ell$$^{-1}$ , respectively. The growth rate of C. polykrikoides, isolated from the study area, was 0.3~0.4 d$^{-1}$ at 20~$25^{\circ}C$, which enable this species to reach the maximum concentration without being transported from the adjacent waters containing already made red tide patches. The outbreaks of red tides dominated by C. polykrikoides in the study area and off Kohung have occurred when and/or where the concentrations of diatoms were low. This evidence suggests that the outbreak of red tides dominated by C. polykrikoides is adversely affected by the high diatom concentrations or the conditions favorable for the growth of diatoms.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.189-206
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• 2015

The present study was conducted to investigate the oceanic characteristics of the northern East China Sea through identification of long-term variation patterns of oceanic environment factors, for the objective of gaining understanding of oceanic environment characteristics of the northern waters of East China Sea, which closely influence the oceanic environments of waters nearby South Korea. The study methodology included the use of oceanographic data (water temperature, salinity, dissolved oxygen, nutrients, and chlorophyll-a) on the northern East China Sea from the Korea Oceanographic Data Center (KODC), collected by season for 20 years between 1995 and 2014. Moreover, for the study on the distribution of nutrients, chlorophyll-a. The main water masses that affected the northern East China Sea during the study period were classified as Changjiang diluted water (CDW), Tiawan current warm water (TCWW), Yellow Sea cold water (YSCW), and Kuroshio source water (KW). The forces of CDW and TCWW that forms on the surface and sub-surface layers had weakened for 20 years and the force of KW that forms on the intermediate layer showed a distinctively decreasing trend. However, YSCW showed a trend of expanding its force. Phosphate and silicate exhibited a decreasing tendency and phosphate showed a pattern of being depleted on the surface layer after 2009. It is determined that one of the reasons for this is the concentration of nutrients introduced through CDW and TCWW being too low. The concentration of chlorophyll-a exhibited an increasing tendency during the study period, the reasons for which are determined to be the influences of increase in water temperature, supply of nutrients via YSCW, and increases in light transmission from decrease in suspended solid due to the construction of the Three Gorges Dam.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.423-435
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• 2001

The gold-silver vein deposits in the Mugeug mineralized area are emplaced in late Cretaceous biotite granite associated with the pull-apart type Cretaceous Eumseong basin. Mugeug mine in northern part is composed of multiple veins showing relatively high gold fineness and is characterized by sericitization, chloritization and epidotization. The ore-forming fluids were evolved by dilution and cooling mechanisms at relatively high temperature and salinity (=30$0^{\circ}C$,1~9 equiv. wt. % NaCl) and highly-evolved meteoric water ($\delta$$^{18}$ O;-1.2~3.7$\textperthousand$) and gold mineralization associated with sulfides tormed at temperatures between 260 and 22$0^{\circ}C$ and within sulfur fugacity range of 10$^{-11.5}$ ~ 10$^{-13.5}$ atm. In contrast, Geumwang, Geumbong and Taegueg mines show the low fineness values, in southern part are characterized by increasing tendency of simple and/or stockwork veins and by kaolinitization, silicificatitan, carbonatization and smectitization. These droposits formed at relatively low temperature and salinity (<23$0^{\circ}C$, <3 equiv. wt. % NaCl) from ore-forming fluids containing greater amounts of less-evolved meteoric waters ($\delta$$^{18}$ O;-5.5~4.0$\textperthousand$), and silver mineralization representing various gold-and/or silver-bearing minerals formed at temperatures between 200 and 15$0^{\circ}C$ and from sulfur fugacity range of 10$^{-15}$ ~10$^{-18}$ atm These results imply that mineralization in the Mugueg area formed at shallow-crustal level and categorize these deposits as low-sulfidation epithermal type. The genetic differences between the northern and southern parts reflect the evolution of the hydrothermal system due to a different physicochemical environment from heat source area (Mugeug mine) to marginal area (Taegeum mine) in a geothermal field.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.53-65
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• 2014

In order to estimate the effect of nutrients addition for phytoplankton growth and community compositons in spring and summer season, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Nutrient additional experiments were also conducted to identify any additional nutrient effects on phytoplankton assemblage using the surface water for the assay. Bacillariophyceae occupied more than 90% of total phytoplankton assembleges. Of these, diatom Eucampia zodiacus and Skeletonema costatum-like species was mainly dominated in spring and summer, respectively. Here, we can offer the season why the two diatom population densities were maintained at high levels in both seasons. First, light transparency of spring season in the euphotic zone was greatly improved in the bay. This improvement is one of important factor as tigger of increase in E. zodiacus population. Second, low salinity and high nutrient sources supplied by Seomjin River discharge are a main cue for strong bottom-up effects on S. costatum-like species during the summer rainy season. Based on the algal bio-assays, although maximum growth rate of phytoplankton communities at inner bay (St.8) were similar to those of outer bay (St.20), half-saturation constant ($K_s$) for phosphate at outer bay was slightly lower than those of inner bay. This implied that adapted cells in low nutrient condition of outer bay may have enough grown even the low phosphate and they also have a competitive advantage against other algal species under low nutrient condition. In particular, efficiency of N (+) addition in summer season was higher compared to control and P added experiments. In the bay, silicon was not a major limiting factor for phytoplankton growth, whereas nitrogen (N) was considered as a limiting factor during spring and summer. Therefore, a sufficient silicate supply form water mixing Si recycled from diatom decomposition and river water is favorable form maintaining diatom ecosystems in Gwangyang Bay.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.199-213
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• 2008

Saemangeum salt-water Lake has been created by the completion of the sea-dike in April 2006. To monitor the water qualities of the lake during the sea-dike construction, salinity, SS, nutrients(DIN, DIP, DISi), and chlorophyll-$\alpha$ was analyzed for the surface water from 1999 to 2007. Due to the dike construction, weaker tidal current and lesser resuspension of bottom sediment resulted in the marked decrease of the concentrations of SS in the lake water. Consequently the clearer lake water has provided better condition for primary production with deeper penetration of sunlight into the water column and sufficient nutrient content in the water. Finally the chlorophyll-$\alpha$ content became approximately double in the concentration after the dike construction. Highly stimulated algal production with the marked decrease of the concentrations of SS was decreased the concentration of DIP in the surface water. On the other hand the concentration of DIN and DISi in surface water was increased after dike construction due to the expansion of the freshwater and the supply from bottom layer. As a result, the lake revealed an extremely high NIP ratio and a DIP-limited ecosystem. The lake has been transformed from a typical coastal ecosystem to a brackish one. Since the dike completion, the lake has shown a similar change pattern to the Geum River estuary. Due to the salt-wedge intrusion of seawater, it is highly probable to expect the formation of low-oxygen zone at the bottom layer near the river-mouth area of the lake during the summer. Therefore we need a continuous sentinel monitoring of bottom water qualities in the near future.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.1-11
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• 2004

The limnological characteristics of a coastal lagoon were studied in Lake Hyangho, one of a series of brackish lagoons along the eastern coast of Korea. Phytoplankton community structure, physical factors, and chemical factors were surveyed from May 1998 through November 2002 on a two-month interval basis. Temperature, salinity, Secchi disc transparency, TN, TP, organic matter content of sediment, chlorophyll a concentration, dominant phytoplankton species, and phytoplankton cell density were measured. Salinity gradient was formed between the overlying freshwater stream water and the permeated seawater at the bottom. The chemocline was persistent at the depth of 2 ${\sim}$ 5 m that caused discontinuities of salinity, DO, and temperature profiles. The inversion of vertical temperature profiles with higher temperature in deeper layer was observed in early winter. Secchi disc transparency was very low with the range of 0.1 to 1.1m. TP, TN, and Chl. a concentration in the epilimnion was 0.011 ${\sim}$ 0.238 mgP $L^{-l}$, 0.423 ${\sim}$ 2.443 mgN $L^{-l}$, and 0.7 ${\sim}$ 145.2 mg $m^{-3}$, respectively. Sediment was composed of silt and coarse silt. COD, TP, and TN content of dry sediment were 19.7 ${\sim}$ 73.3 mg$O_2\;g^{-1}$, 0.61 ${\sim}$ 1.32 mgP $g^{-l}$ and 0.64 ${\sim}$ 0.88 mgN $g^{-l}$, respectively. Dominant phytoplankton species were chlorophytes (Ankistrodesmus falcatus) and cyanobacteria (Oscillatoria sp. and Merismopedia tennuissima). The total cell density was in the range of 560 ${\sim}$ 35,255 cells $mL^{-l}$.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.4
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• pp.357-368
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• 2003

Time-series CTDT (Conductivity/Temperature/Depth/Transmissivity) were obtained at one point near tidewater glacier of Marian Cove (King George Islands, Antarctica) to present water column properties and SPM (suspended particulate matter) dispersal pattern in relation with tide, current, meteorological data, and SPM concentration. Four layers were divided from the water column characteristics measured in the interval of an hour for about 2 days: 1) cold, fresh, and turbid surface mixed layer between 0-20 m in water depth, 2) warm, saline, and relatively clean Maxwell Bay inflow between 20-40 m in water depth, 3) turbid/cold tongue of subglacial discharges compared with the ambient waters between 40-70 m in water depth, and 4) cold, saline, and clean bottom water beneath 70 m in water depth. Surface plume, turbid freshwater at coastal/cliff area in late summer (early February), had the characteristic temperature and SPM concentration according to morphology, glacial condition, and composition of sediments. The restrict dispersion only over the input source of meltwater discharges was due to calm wether condition. Due to strong wind-induced surface turbulence, fresh and turbid surface plume, englacial upwelling cold water, glacier-contact meltwater, and Maxwell Bay inflow was mixing at ice-proximal zone and the consequent mixed layer deepened at the surface. Large amount of precipitation, the major controlling factor for increasing short-term glacial discharges, was accompanied by the apparent development of subglacial discharge that resulted in the rapid drop of salinity below the mid depth. Although amount of subglacial discharge and englacial upwelling may be large, however, their low SPM concentration would have small influence on bottom deposition of terrigenous sediments.