• Journal of Korean Society for Atmospheric Environment
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• v.31 no.6
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• pp.548-561
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• 2015

Atmospheric concentrations of polychlorinated dibezo-p-dioxins and furans (PCDD/Fs) were investigated at urban-residential (Group I: Suwon, Guri and Goyang), industrial (Group II: Ansan, Siheung and Bucheon), urban-rural mixed (Group III: Yangju, Pocheon and Dongducheon) and rural regions (Group IV: Yangpyeong) in Gyeonggi-do from February 2012 to November 2012 quarterly. The concentrations of PCDD/Fs ranged from 0.018 to $0.109pgTEQm^{-3}$ in Group I (mean value: $0.061pgTEQm^{-3}$), 0.059 to $0.367pgTEQm^{-3}$ in Group II (mean value: $0.179pgTEQm^{-3}$), 0.072 to $0.836pgTEQm^{-3}$ in Group III (mean value: $0.334pgTEQm^{-3}$) and 0.014 to $0.066pgTEQm^{-3}$ in Group IV (mean value: $0.034pgTEQm^{-3}$), respectively. In spite of the less PCDD/F emission sources than Group II (industrial regions), the level of PCDD/Fs in urban-rural mixed area showed the highest values with high fluctuation. It's likely that the Group III was affected by fugitive emissions such like biomass burning and unregulated open burning. The mean contribution of particle phase to total PCDD/F concentration was above 83% because most of PCDD/F congeners were partitioned into particle phase. We evaluated their gas-to-particles equilibriums with the regression between the particle-gas partition coefficient, $K_P(m^3{\mu}g^{-1})$ and corresponding subcooled liquid vapor pressure ($P_L$). The logarithm-$K_P$ of PCDD/Fs was poorly correlated with $P_L$ at low ambient temperature (below $10^{\circ}C$) and the slope (m) values for log-log plots of the $K_P$ vs. $P_L$ was steeper in the Group 2 and Group 3 than residential area. It implies that the slope values were likely influenced by both the direct emission source of PCDD/Fs and ambient temperature.

• Korean Journal of Environmental Biology
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• v.34 no.1
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• pp.56-62
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• 2016

Pest population density models are very important to monitor the initial occurrence and to understand the continuous fluctuation pattern of pest in pest management. This is one of the major issues in agriculture because these predictions make pesticides more effective and environmental impact of pesticides less. In this study, we combined and predicted the mortality change of pest caused by pesticides with temperature change and population dynamic model. Sensitive strain of two-spotted spider mite (Tetranychus urticae Koch) with kidney bean leaf as host was exposed to mixed acaricide, Acrinathrin-Spiromesifen and organotin acaricide, Azocyclotin, at 20, 25, 30, and $35^{\circ}C$, respectively. There was significant difference in mortality of T. urticae among pesticides and temperatures. We used DYMEX to simulate population density of T. urticae and predicted that the initial management time and number of chemical control would be changed in the future with climate change. There would be implications for strategies for pest management and selection process of pesticide in the future corresponding climate change.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.1
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• pp.24-37
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• 2001

Physical and chemical properties of the northest Equatorial Pacific between 5° and 12° N along 131.5 °W wore investigated in association with changes in water column structures during the summer seasons of 1998 and 1999. Climatic disturbances such as El Nino and La Nina, should have affected this area during the study Period. In 1998, a thermocline where temperature rapidly decrease with depth, was formed at 90～110 m water depth. Nutrient depicting areas, specially for nitrate+nitrite and phosphate, or oligotrophic regions were extended down to approximately 100 m depth, which coincided with the surface mixed layer depth. However, in 1999, a very fluctuating thermocline was observed with latitudes. As a result of changes in the water column structures, nutrient concentrations also showed fluctuation parallel to the changes in other physical parameters. In the photic zone, depth integrated nitrogen and phosphorus values were 34 gN/m², 7 gP/m² in 1998 and 130 gN/m², 18 gP/m² in 1999, respectively. The results indicated that nitrogen (96 gN/m²) and phosphorus (11 gP/m²) are supported by up-welling and down-welling phenomena with convergence and divergence in the study area.

• Korean Journal of Food Science and Technology
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• v.22 no.1
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• pp.26-32
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• 1990

Attempts were made to define the characteristics of microbial community as an indicator of Kimchi fermentation. Determination of communities was carried out by simple Gram-stain, followed by direct microcopic counts. In room-temperature $(15^{\circ}C)$ fermentation, microbial succession was occurred in the order of communities of Gram-positive bacteria, yeasts and Gram-negative bacteria. It was characteristic that Gram-positive bacterial community was developed during the production of lactic acid, yeasts community was developed to cause rancidity, and Gram-negative bacterial community was relevant to maceration (or softening) as well as rancidity. The fluctuation of apparent Gram-negative reaction group might be used as a criterion of death or aging of Gram-positive bacterial populations. In low-temperature fermentation $(5^{\circ}C)$, however, it was found that yeasts and Gram-negative bacterial communities did not developed but only Gram-positive bacterial community did. It follows from these results mentioned above that maturity of Kimchi depends on the development of Cram-positive bacterial community. Thus, the size and occurrence of microbial community are avaiable for an indicator of Kimchi fermentation, and also determination of community could be a useful method to predict the maturity.

• Korean journal of applied entomology
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• v.18 no.3 s.40
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• pp.127-132
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• 1979

This experiments were performed to investigate the temperature effects, which caused by the various types of collecting trap treatments, during the overwintering period of pine gall midge larvae, on the peak adult emergence time. And the following results were obtained. 1) The maximum temperatures inside of the collection traps were significantly different each other, and the vinyl cage showed the highest degree which highering $15^{\circ}C$, and standard cage, cage-50 and funnel trap highering $3-12^{\circ}C$ in monthly average comparing to control. 2) There was no significant difference among the treatment in minimum temperatures, during the overwintering periods of larvae. 9) The peak adult emergence time were May 15 in vinyl cage plot which shortened 20 days and both standard cage and cage-50 shortened 14 day than that of control. 4) The funnel type trap treatment delayed 6 days of the peak adult emergence comparing to control, in spite of the treatment showing higher maximum and cumulative temperatures than the control plot. 5) The decadal maximum temperatures of middle part of December and March were significantly correlated with the shortening of the peak adult emergence date.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.12-19
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• 2015

In this paper, temporal variations of acoustic transmission loss (TL) affected by internal tide are studied by computer simulation using oceanic data measured in the southern sea of Jeju Island in summer. Temperature was measured with depth (bottom depth are nearly 80 m) in two sites near Seogwipo coast every one hour for 25 hours during July 27 and 28, 2009. The periodic fluctuation of temperature due to the internal tide was observed and its vertical displacement was more than 10 m. In order to investigate temporal variation of TL by internal tide, acoustic propagation between two measurement sites (3.8 km distance) was simulated with a source depth of 10 m. TL variation for 1/3 octave band of 100 Hz center frequency highly coincided with tidal period but more complex variation with indistinct tidal period was observed for 1 kHz. Maximun standard deviation of TL variation was 4.2 dB for 100 Hz at 2.8 km distance from a source and it was 3.7 dB for 1 kHz. The tidal variation was also shown in detection range and its maximum variance was less than 1 km. These results imply that temporal variation of TL should be considered for acoustic researches at the southern sea of Jeju Island.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.366-372
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• 1985

Soil temperatures and soil physical properties were investigated in order to better understand the effects of mulchings in the red pepper field. The red pepper was planted in the lysimeter installed at the Yesan sandy loam with 20% slope and 10cm slope length. The results were summarized as follows: 1. Average soil temperatures at 10cm and 20cm depth in vinyl mulching plots were $1.6^{\circ}C$ and $1.1^{\circ}C$ higher than those of control, respectively. However, the average soil temperatures in rice straw mulching plots were relatively lower than those of control during the growing season. 2. The greatest diurnal fluctuation of soil temperature was found at the vinyl mulching plots and it was decreased with increasing soil depth. 3. The calculated thermal diffusivities were 0.011, 0.009 and $0.007cm^2/sec$ for the vinyl mulching, control and straw mulching, respectively. 4. Soil losses were 103kg/10a for the vinyl mulching and 36kg/10a for the straw mulching which were nearly negligible as compared to the control. 5. Soil physical properties such as bulk density, hardness and water content were significantly improved by the vinyl and straw mulchings.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.243-255
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• 2014

This study was investigated to estimate the relations between benthic environments and benthic polychaetous community from April 2012 to February 2013. Twenty four stations were selected sequentially with Seomjin River Estuary from the northern part of Gwangyang Bay. The study area could be divided into three characteristic zones based on salinity, water temperature, dissolved oxygen and pH such as Saline Water Zone (SWZ), Brackish Water Zone (BWZ), and Fresh Water Zone (FWZ). Salinity was above 30.0 psu in SWZ, drastically decreased toward inland in BWZ, and nearly zero psu in FWZ. SWZ showed its specific environmental characters like that water temperature fluctuated with little seasonal change and DO showed the lowest values among three zones, and pH maintained as consistent value without seasonal fluctuation. In FWZ, on the other hand, water temperature showed high seasonal fluctuation, DO showed the highest values among three zones, and pH fluctuated greatly. In sedimentary environment, mud, sand and sand/gravel were found as dominant sedimentary deposits in SWZ, BWZ and FWZ, respectively. Organic matter content and AVS in surface sediment were high in SWZ, while Chl-a content high in FWZ. This study area showed a marked environmental difference between FWZ and SWZ as follows: FWZ has coarse sediment and low salinity, low organic matter content, low AVS in FWZ but SWZ has fine sediment and high salinity, high organic matter content and AVS. Species number and mean density of benthic polychaete community was highest in Saline Water Zone (SWZ), drastically decreased in Brackish Water Zone (BWZ), and lowest in Fresh Water Zone (FWZ). Dominant polychates above 5.0% of individual numbers were 6 taxa. Lumbrineris longifolia, Prionospio cirrifera, Tharyx sp. occurred as main dominant species of all study periods, and Hediste sp., Praxillella affinis, Tylorrhynchus sp. dominantly occurred at some seasons. Inhabiting areas of dominant species were separated characteristically. Representative species in SWZ were Lumbrineris longifolia, Tharyx sp., Mediomastus sp.. Wide-appearing species between SWZ and BWZ were Prionospio cirrifera, Heteromastus filiformis, Aricidea sp.. Characteristic species in FWZ were Tylorrhynchus sp. and Hediste sp.. As the results of cluster analysis and nMDS based on the species composition of polychaetous community, unique station groups were established in SWZ and FWZ. Stations in BWZ were sub-divided into several groups with season. Pearson's correlation analysis and PCA between benthic environments and ecological characteristics of polychaetous community showed that salinity, sediment composition, organic content and dissolved oxygen played a role to determine the temporal and spatial distribution of the ecological characteristics as species number, mean density, abundance of main species, and ecological indices.

• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.216-224
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• 2014

Decrease in dissolved oxygen concentrations associated with temperature fluctuation is an important criteria to evaluate the mortality rate of the species. Based on this parameter, we investigated the survival rate, physiological response and histological change of warty sea squirt. It was found that the survival rate of the warty sea squirt species was 63.3% at $23^{\circ}C$ and 56.6% at $26^{\circ}C$ respectively. However, exposure of six days at $29^{\circ}C$ caused deaths among species, which indicated the 6day-$LT^{50}$ of the tested species to be $24.58^{\circ}C$ ($19.48{\sim}35.48^{\circ}C$). Further, after 11 day of exposure, the dissolved oxygen concentration has been found to decrease, with the survival rate of 20% at $4.0mg\;L^{-1}$ and deaths at $2.0mg\;L^{-1}$, thus 11day-$LC^{50}$ calculated to be $3.88mg\;L^{-1}$ ($3.29{\sim}4.57mg\;L^{-1}$). In addition, decrease in rate of oxygen consumption and excretion of ammonia was also noted at this critical water temperature and dissolve doxygen concentration. Moreover, there has been common histopathological changes were observed in warty sea squirt's gill pouch, digestive tract, and tunic as follows such as: proliferation of epithelial cells, condensation and necrosis, permeation of phagocyte and blood cell, loss of cilium and muscular fiber degeneration. Based on our study results, we suggest that these parameters can also be useful to evaluate the survival rate and physiological response in other species.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.177-184
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• 2005

This study was to determine the fluctuation in phytoplankton assemblages with regarding to environmental conditions and nutrients, which were surveyed around Mokpo waters in the southwestern waters, Korea. Sampling was carried out on the Mokpo, Sinan, and Wando coasts from March to November 2003. The maximum sea surface temperature was recorded in August, and it ranged around $25^{\circ}C$ regardless of sampling sites. However, salinity in Mokpo waters showed a great variation, which ranged from 5-30 psu and recoded the minimum of 5 psu in July and the maximum of 30 psu in November. Moreover, in Mokpo waters, the chlorophyll a and SS concentration of the surface layer were also the highest values of $20\;{\mu}g\;l^{-1}\;and\;40\;{\mu}g\;l^{-1}$, respectively than those of Sinan and Wando waters. The concentrations of $NH_4-N,\;NO_2-N,\;NO_3-N,\;and\;PO_4-P$ were also he highest values of $0.018\;{\mu}mol\;^l{-1},\;0.062\;{\mu}mol\;l^{-1},\;1.2\;{\mu}mol\;l^{-1}\;and\;0.078\;{\mu}mol\;l^{-1}$, respectively in Morpo waters than those of Sinan and Wando waters. During the period of this study, the majority of the taxa were diatoms; Thalassiosira rotula, Rhizosolenia setigera, Prorocentrum minimum, Chaetoceros curvisetus, Leptocylindrus danicus, Pseudonitzschia pungens, and Chaetoceros spp. were detected in the dominant species of phytoplankton. The dinoflagellates were relatively abundant during the summer season in Wando waters, which attained an abundance of $10-20\%$. In Mokpo waters, DIN/DIP was the highest value of 700 in March, whereas the lowest was shown in Wando waters. However, DIN/DIP value in summer at Wando waters was extremely reversed, which appeared to be associated with the development of dinoflagellates. On the bais of factor analysis using SYSAT 6.0, nutrient showed somewhat correlation with chlorophyll a. Consequently, the process of discharge of fresh water in Mokpo waters plays an important role in extremely fluctuation in nutrients and conditions. Although Wando waters maintains a lack of nutrients, it should be influenced by different water current and may be associated with a concentration of nutrients.