• Spatial Information Research
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• v.16 no.4
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• pp.467-478
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• 2008

This study analyzes the spatial and temporal variability of temperature ($^{\circ}C$) and precipitation (mm) in Seoul, Korea. The temperature and precipitation data were measured at 31 automatic weather stations (AWSs) in Seoul for 10 years from 1997 to 2006. In this study, inverse distance squared weighting (IDSW) was applied to interpolate the non-measured spaces. To estimate the temperature and precipitation variability, the mean values and frequencies of hot and cold days were examined. The maximum and minimum temperatures were $32.80^{\circ}C$ in 1999 and $-19.94^{\circ}C$ in 2001, respectively. The year 2006 showed the highest frequency of hot temperatures with 79 hot days, closely followed by 2004 and 2005. The coldest year was in 2001 with 105 cold days. The annual mean temperature and precipitation increased by about $1^{\circ}C$ and 483mm during the 10-year period, respectively. The temperature variability differed between high-elevation forested areas and low-elevation residential areas. However, the precipitation variability showed little relation with the topography and land use patterns.

• Korean Journal of Ichthyology
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• v.20 no.3
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• pp.190-197
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• 2008

Spatio-temporal distribution of eggs and larvae of Japanese anchovy Engraulis japonica in the southern sea of Korea was determined using data obtained from icthyoplanktonic surveys and oceanographic observations between Goheung Peninsula and Goeje Island from May to August 2007. Commercial anchovy catch and size composition from four local fishery cooperative associations were also analyzed in relation to the geographic distribution of eggs and larvae. The abundance of anchovy eggs increased from May to July and was lowest in August. Eggs were mainly distributed between Namhae Island and Goeje Island, where water temperatures were $15{\sim}24^{\circ}C$ and salinities were 32~35‰. In 2007 anchovy landings between Namhae Island and Goeje Island were 11,409 tons at Tongyeong association, 4,137 tons at Masan association, and 2,487 tons at Sacheon association. However, landings between Goheung and Yeosu Peninsula were only 4,411 tons (at Yeosu association). The catch by anchovy tow net was high in the area where eggs were abundantly distributed. This indicates that the distribution of egg density was directly correlated with recruitment of E. japonica. All growth stages were abundant in the study area, indicating that this area is a major spawning and growing ground of E. japonica in Korean waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.415-430
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• 1996

Spatio-temporal variations in zooplankton community and ropepod indicator species were investigated along with the interaction between zooplankton distribution and environmental factors in Chinhae Bay. Zooplankton samples were monthly collected at 7 stations from February to September in 1993. A NORPAC net was vertically hauled from bottom to surface, At the same station, environmental factors such as temperature, salinity and COD (chemical oxygen demand) were measured at two different water layers, surface and bottom. In August and September, salinity declined below 30.00‰ , while eutrophic parameters such as COD showed the higher concentrations than those in other months, with higher concentrations at inner bay stations. Salinities were, however, higher at bay mouth areas. These distributional patterns were believed to be caused by input and dispersion of organic matters from nearby land. Zooplankton communities were composed of 7~14. Of these, Noctiluca scintillans was predominant and occupied 90.6‰ of total zooplankton abundance. Cladocera and Copepoda were secondly abundant taxa. Among 6 to 10 copepod species appeared, Acartia omorii and A. hudsonics were most common species during the survey months except March and September. Species diversities were greater, in general, at inner bay than outer bay. The lowest diversity index was observed in February, while the highest in July. Cluster analysis could divide the study area into 2 or 4 zones for each month. Zone 1, mouth area of the bay, was characterized by the influence of offshore waters. Zone II was mixing area. Zone III and IV seemed to be affected by nearby land.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.86-94
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• 2000

In order to extract the spatio-temporal characteristics of long-term variability of the net heat flux on the sea surface in the East Asian marginal seas, empirical orthogonal function (EOF) analysis was conducted using data set calculated every 12 hours interval during 1978-1995. Among the first three modes explaining 73% of the total variance, the first mode having high peak at 1 year period indicates high variability area around the Sandong Peninsula and central and northeastern part of the East Sea. In the second mode which has spatial distribution of dipole type at the north and south, the peaks appear at 3.6 year and 2.3 year cycles. Time coefficient of the second EOF is believed to have close relation with the E1 Nino and has out-of-phase variation with NINO3 SST. Lagged correlation between NINO3 SST and time coefficient of the second EOF indicates four month time delay in the NINO3 SST. In the third mode which has opposite sign at the east and west, the periodicity of 6-9 year cycle has relatively clear appearance compared to other two EOFs. Also, high heat loss exceeding 800 W/$m^{2}$ in winter time occured at the south part of the Sandong Peninsula and Vladivostok. It reveals more frequent occurrence of about two times at the Sandong Peninsula than Vladivostok. The event is concentrated in January at Vladivostok, but it occurs primarily in December and January at the Sandong Peninsula.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.2
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• pp.129-138
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• 2007

The cases of drunk driving accidents have been steadily increasing every year. The number of accidents was quadrupled from 7,303 cases in 1990 to 25,150 cases in 2004. In addition, the proportion of drunk driving accidents to total traffic accidents was 2.9% in 1990 but it increased to 13.0% in 2003. Studies of drunk driving accidents have been focusing on analyzing psychological decisive factors, classifying drivers' individual characters and types of drunk driving accidents by considering the location of drunk driving accidents. This study assumed that drunk driving accidents would have regular characteristics in respect to spatiality and analyzed its relation with spatial factors such as, accident black spot, the location of bars, the distance of drivers' houses, and spatio-temporal distributional characteristics through drawing density distribution and connecting the time of accidents. In order to achieve the goal of this study, the individual location information was organized and drawn as types of GIS data. From the result of density distribution using Kernel Density Mapping and analysis through the coefficient of areal correspondence, it was understood that drunk driving accidents correlates with some spatial factors.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.73-84
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• 2006

The objective of this study was to analyze long-term temporal trends of water chemistry and spatial heterogeneity for 10 sampling sites of the Yeongsan River watershed using water quality dataset during 1995 to 2004 (obtained from the Ministry of Environment, Korea). The water quality, based on multi-parameters of biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, dissolved oxygen (Do), total phosphorus (TP), total nitrogen (TN) and total suspended solids (TSS), largely varied depending on the sampling sites, seasons and years. Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of summmer monsoon rain. Conductivity, used as a key indicator for a ionic dilution during rainy season, and nutrients of TN and TP had an inverse function of precipitation (absolute r values> 0.32, P< 0.01, n= 119), whereas BOD and COD had no significant relations(P> 0.05, n= 119) with rainfall. Minimum values in conductivity, TN, and TP were observed during the summer monsoon, indicating an ionic and nutrient dilution of river water by the rainwater. In contrast, major inputs of total suspended solids (TSS) occurred during the period of summer monsoon. BOD values varied with seasons and the values was closely associated (r=0.592: P< 0.01) with COD, while variations of TN were had high correlations (r=0.529 : P< 0.01) with TP. Seasonal fluctuations of DO showed that maximum values were in the cold winter season and minimum values were in the summer seasons, indicating an inverse relation with water temperature. The spatial trend analyses of TP, TN, BOD, COD and TSS, except for conductivity, showed that the values were greater in the mid-river reach than in the headwater and down-river reaches. Conductivity was greater in the down-river sites than any other sites. Overall data of BOD, COD, and nutrients (TN, TP) showed that water quality was worst in the Site 4, compared to those of others sites. This was due to continuous effluents from the wastewater treatment plants within the urban area of Gwangju city. Based on the overall dataset, efficient water quality management is required in the urban area for better water quality.

• Korean Journal of Ecology and Environment
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• v.45 no.2
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• pp.158-173
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• 2012

The objectives of this study were to analyze the longitudinal gradient and temporal variations of water quality in Daecheong Reservoir in relation to the major inflowing streams from the watershed, during 2001~2010. For the study, we selected 7 main-stream sites of the reservoir along the main axis of the reservoir, from the headwater to the dam and 8 tributary streams. In-reservoir nutrients of TN and TP showed longitudinal declines from the headwater to the dam, which results in a distinct zonation of the riverine ($R_z$, M1~M3), transition ($T_z$, M4~M6), and lacustrine zone ($L_z$, M7) in water quality, as shown in other foreign reservoirs. Chlorophyll-a (CHL) and BOD as an indicator of organic matter, were maximum in the $T_z$. Concentration of total phosphorus (TP) was the highest (8.52 $mg\;L^{-1}$) on March in the $R_z$, and was the highest (165 ${\mu}g\;L^{-1}$) in the $L_z$ on July. Values of TN was the maximum (377 ${\mu}g\;L^{-1}$) on August in the $R_z$, and was the highest (3.76 $mg\;L^{-1}$) in the $L_z$ on August. Ionic dilution was evident during September~October, after the monsoon rain. The mean ratios of TN : TP, as an indicator of limiting factor, were 88, which indicates that nitrogen is a surplus for phytoplankton growth in this system. Nutrient analysis of inflowing streams showed that major nutrient sources were headwater streams of T1~T2 and Ockcheon-Stream of T5, and the most influential inflowing stream to the reservoir was T5, which is located in the mid-reservoir, and is directly influenced by the waste-water treatment plants. The key parameters, influenced by the monsoon rain, were TP and suspended solids (SS). Empirical models of trophic variables indicated that variations of CHL in the $R_z$ ($R^2$=0.044, p=0.264) and $T_z$ ($R^2$=0.126, p=0.054) were not accounted by TN, but were significant (p=0.032) in the $L_z$. The variation of the log-transformed $I_r$-CHL was not accounted ($R^2$=0.258, p=0.110) by $I_w$-TN of inflowing streams, but was determined ($R^2$=0.567, p=0.005) by $I_w$-TP of inflowing streams. In other words, TP inputs from the inflowing streams were the major determinants on the in-reservoir phytoplankton growth. Regression analysis of TN : TP suggested that the ratio was determined by P, rather than N. Overall, our data suggest that TP and suspended solids, during the summer flood period, should be reduced from the eutrophication control and P-input from Ockcheon-Stream should be controlled for water quality improvement.