• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.4
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• pp.229-241
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• 2006

Global air temperature has risen by $0.6^{\circ}C$ over the last one hundred years due to increased atmospheric greenhouse gases. Moreover, this global warming trend is projected to continue in the future. This study was carried out to evaluate spatial variations in rice production areas by simulating rice-growth and development with projected high resolution climate data in Korea far 2011-2100, which was geospatially interpolated from the 25 km gridded data based on the IPCC SRES A2 emission scenario. Satellite remote sensing data were used to pinpoint the rice-growing areas, and corresponding climate data were aggregated to represent the official 'crop reporting county'. For the simulation experiment, we used a CERES-Rice model modified by introducing two equations to calculate the leaf appearance rate based on the effective temperature and existing leaf number and the final number of leaves based on day-length in the photoperiod sensitive phase of rice. We tested the performance of this model using data-sets obtained from transplanting dates and nitrogen fertilization rates experiments over three years (2002 to 2004). The simulation results showed a good performance of this model in heading date prediction [$R^2$=0.9586 for early (Odaebyeo), $R^2$=0.9681 for medium (Hwasungbyeo), and $R^2$=0.9477 for late (Dongjinbyeo) maturity cultivars]. A modified version of CERES-Rice was used to simulate the growth and development of three Japonica varieties, representing early, medium, and late maturity classes, to project crop status for climatological normal years between 2011 and 2100. In order to compare the temporal changes, three sets of data representing 3 climatological years (2011-2040, 2041-2070, and 2071-2100) were successively used to run the model. Simulated growth and yield data of the three Japonica cultivars under the observed climate for 1971-2000 was set as a reference. Compared with the current normal, heading date was accelerated by 7 days for 2011-2040 and 20 days for 2071-2100. Physiological maturity was accelerated by 15 days for 2011-2040 and 30 days for 2071-2100. Rice yield was in general reduced by 6-25%, 3-26%, and 3-25% per 10a in early, medium, and late maturity classes, respectively. However, mid to late maturing varieties showed an increased yield in northern Gyeonggi Province and in most of Kwangwon Province in 2071-2100.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.335-345
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• 1996

A critical role of oxygen-derived free radicals has been implicated in ischemia/reperfusion (I/R)-induced brain damage. In this study, we have produced experimental I/R to the brains of Mongolian gerbil (Meriones unguiculatus) by a transient occlusion and release of the common carotid arteries. We have attempted to determine whether the oxidative stress is generated upon I/R and whether this oxidative stress is linked to the cell damage. Since hippocampus has been suggested as one of the most vulnerable regions of the brain to the oxidative stress, we analyzed samples from hippocampus in comparison with those from cortex. In addition, we have examined the expression of heat shock protein 70kD species (HSP70) in these regions in order to evaluate a possible role of this protein in I/R-induced brain damage. To determine whether the oxidative stress is produced upon I/R, we measured the glutathione oxidation, GSSG/ (GSH + 2xGSSG), as an index of oxidative stress. We found an increase of the glutathione oxidation primarily in hippocampus upon I/R. To determine whether this oxidative stress is linked to the cell damage, we measured the degree of lipid peroxidation upon I/R. We found an increase of lipid peroxidation in both regions. However, the magnitude of increases was greater in hippocampus than in cortex. In addition, we found that changes in both the magnitude and the temporal patterns of glutathione oxidation closely correlated with those of lipid peroxidation. Our study provides biochemical evidences that the oxidative stress is generated upon I/R and this oxidative stress is linked to the oxidative cell damage. Our study also provides evidences that the degree of oxidative stress as well as oxidative cell damage is greater in hippocampus than in cortex. We could not find difference in the basal level of HSP70 expression between hippocampus and cortex, indicating that the intrinsic vulnerability of hippocampus cannot be explained by the lower level of HSP70 expression. We did find, however, that the induction of HSP70 expression upon I/R was impaired in the hippocampus. This impairment appeared to be at the transcriptional level. These results suggest that the measurement of HSP70 induction may be employed as a useful predictor of differential cellular susceptibilities to the I/R-induced brain damage.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.4
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• pp.362-371
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• 2016

The distribution patterns of Chromophoric Dissolved Organic Matter (CDOM) and the chemical characteristics of CDOM in the Seomjin river estuary were investigated in March, June and July 2012 in order to determine the spatial and temporal variability of CDOM along the salinity gradient considering the effects of mixing, nutrients and Chl a. The average CDOM values were $1.0{\pm}0.3m^{-1}$, $1.3{\pm}0.4m^{-1}$, and $1.4{\pm}0.3m^{-1}$ in March, June and July, respectively. A high concentration of CDOM (greater than $1.5m^{-1}$) was found at the head of the river which decreased towards the river mouth to as low as less than $0.5m^{-1}$. The average concentrations of CDOM increased from the dry season (March and June) to the wet season (July), and the average slope values ($S_{300-500}$), which were used as indicators of CDOM characteristics and sources, were in the range of $0.013-0.018m^{-1}$. The CDOM and $S_{300-50}$ values showed that not only the concentration of CDOM but also the chemical properties of DOM clearly changed between upstream and downstream in the Seomjin river. CDOM and FDOM showed a negative correlation with salinity ($R^2$ > 0.8), and CDOM was positively correlated with FDOM. Furthermore, the mixing pattern of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM were salinity (mixing) and water temperature, which meant the dilution of low CDOM seawater, was the controlling factor for the spatial distribution of CDOM. Increases in water temperature seemed to induce the production of CDOM during summer (June and July) through the biological degradation of DOM either by microbial activity or photo-degradation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.475-488
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• 1995

In order to see the seasonal variation of nutrients and the limiting factors to the primary production in Deukryang Bay, both dissolved inorganic nutrients and salinity were measured in the surface waters during the periods from July 1992 to March 1993. The mean value of salinity was the lowest in ?all and the highest in early spring. Dissolved inorganic nitrogen (DIN) was the highest in winter and the lowest in summer. However, both phosphate and silicate were the highest in summer and the lowest in fall. Salinity was generally higher in the outer region than in the inner region of the bay.DIN content was nearly depleted (less than $2{\mu}M$) in summer. From fall to spring, DIN content was nearly depleted in the inner region and relatively high in the outer region of the Day. Phosphate was the highest in summer showing an opposite distribution pattern to salinity, and it was nearly depleted (less than $0.1{\mu}M$) in fall and winter. In spring, however, phosphate content was slightly high in the outer region. Silicate content showed an opposite distribution pattern to salinity in summer. in other seasons, However, the distribution pattern of silicate was similar to the salinity. DIN seemed to be a limiting factor for the primary production at all area of the bay in summer and at the inner region in other season. However, phosphate seemed to be a limiting factor at all area of the bay in fall and winter and at the inner region in spring. Silicate may limit the production of diatoms at the inner region of the bay in winter and spying. Both phosphate and silicate showed a good inverse relationship with salinity in summer, which indicates inputs of these nutrients from the freshwater runoff. In the other seasons, both nitrate and silicate showed a positive linear relationship with salinity in the outer region of the bay, suggesting that these two nutrients were mainly supplied by the inflow of the offshore costal water which had high nitrate content associated with vertical mixing.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.2
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• pp.1-15
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• 2002

Atmospheric aerosols interact with sunlight and affect the global radiation balance that can cause climate change through direct and indirect radiative forcing. Because of the spatial and temporal uncertainty of aerosols in atmosphere, aerosol characteristics are not considered through GCMs (General Circulation Model). Therefor it is important physical and optical characteristics should be evaluated to assess climate change and radiative effect by atmospheric aerosols. In this study GMS-5 satellite data and surface measurement data were analyzed using a radiative transfer model for the Yellow Sand event of April 7~8, 2000 in order to investigate the atmospheric radiative effects of Yellow Sand aerosols, MODTRAN3 simulation results enable to inform the relation between satellite channel albedo and aerosol optical thickness(AOT). From this relation AOT was retreived from GMS-5 visible channel. The variance observations of satellite images enable remote sensing of the Yellow Sand particles. Back trajectory analysis was performed to track the air mass from the Gobi desert passing through Korean peninsular with high AOT value measured by ground based measurement. The comparison GMS-5 AOT to ground measured RSR aerosol optical depth(AOD) show that for Yellow Sand aerosols, the albedo measured over ocean surfaces can be used to obtain the aerosol optical thickness using appropriate aerosol model within an error of about 10%. In addition, LIDAR network measurements and backward trajectory model showed characteristics and appearance of Yellow Sand during Yellow Sand events. These data will be good supporting for monitoring of Yellow Sand aerosols.

• Sleep Medicine and Psychophysiology
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• v.7 no.1
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• pp.60-66
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• 2000

Objectives: The Psychopathology of schizophrenia was expected to be related with focal dysfunction of brain while schizophrenia is recognized and studied as the brain disease. Authors studied correlation between neuropsychological tests and delusion which is representative symptom of schizophrenia in patients with head trauma and psychiatric patients in order to explore the functional localization of brain in delusional symptom. Methods: Halstead Reitan Neuropsychological Test Battery and Korean Weschler Intelligent Scale and Minnesota Multiphasic Personality Inventory(MMPI) were administered to one hundred ninteen patients consisted of sixty nine psychiatric patients and fifty patients with brain damage. We tested correlation between results of neuropsychological tests and delusional scale made from twenty four items related with delusion in MMPI. T-test between eighteen higher delusion scorers and twenty one lower scorers was examed in psychiatric group. Results: In brain damage group, signigicant correlations were found in the tests related with function of frontal lobe such as category test, trail making AB test, tactual performance test, digit symbol test and fingertip number writing test, and significant correlations were also noted in the tests related with function of left temporal and parietal lobes such as information, comprehension, vocabulary, similarities and speech sound perception test. The tests related with the function of right hemisphere such as tactual performance test location, picture completion and performance, and the tests related with subcortical function such as arithmetic, digit span, attention, digit symbol test, digit symbol and trail making AB test were signigicantly corelated with delusional scale too. In psychiatric group there were significant difference of delusional score in the tests related with function of left hemisphere such as vocabulary, vocable IQ, comprehension and language, and in the tests related with subcortical function such as N 120 voltage, digit symbol and arithmetic. Conclusions: Delusion seems to be related with function of frontal lobe, left hemisphere and subcortex in both groups. Right hemisphere may be also partially related with delusion.

• Journal of the Korean Geographical Society
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• v.40 no.2 s.107
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• pp.221-241
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• 2005

Land Use and Land Cover Changes (LUCC) occur over a wide range of space and time scales, and involve complex natural, socio-economic, and institutional processes. Therefore, modelling and predicting LUCC demands an understanding of how various measured properties behave when considered at different scales. Understanding spatial and temporal variability of driving forces and constraints on LUCC is central to understanding the scaling issues. This paper aims to 1) assess the heterogeneity of land cover change processes over the landscape in northern Ghana, where intensification of agricultural activities has been the dominant land cover change process during the past 15 years, 2) characterise dominant land cover change mechanisms for various spatial scales, and 3) identify the optimal spatial scale for LUCC modelling in a savanna landscape. A multivariate statistical method was first applied to identify land cover change intensity (LCCI), using four time-sequenced NDVI images derived from LANDSAT scenes. Three proxy land use change predictors: distance from roads, distance from surface water bodies, and a terrain characterisation index, were regressed against the LCCI using a multi-scale hierarchical adaptive model to identify scale dependency and spatial heterogeneity of LUCC processes. High spatial associations between the LCCI and land use change predictors were mostly limited to moving windows smaller than 10$\times$10km. With increasing window size, LUCC processes within the window tend to be too diverse to establish clear trends, because changes in one part of the window are compensated elsewhere. This results in a reduced correlation between LCCI and land use change predictors at a coarser spatial extent. The spatial coverage of 5-l0km is incidentally equivalent to a village or community area in the study region. In order to reduce spatial variability of land use change processes for regional or national level LUCC modelling, we suggest that the village level is the optimal spatial investigation unit in this savanna landscape.

• Journal of the Korean Geographical Society
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• v.42 no.5
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• pp.808-834
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• 2007

This study attempts to elucidate manifold dimensions of gendered accessibility experiences. How gender roles(household responsibilities) differentiate accessibility experiences between women and men is explored through the comparison of married dual-earner couples' parental status, using the US Portland activity-travel diary dataset with GIS-based geocomputation results of(time-geography based) space-time accessibility. First, this study shows how gender division of labor within the household still permeates current society, despite the widespread belief of the social change toward a gender-egalitarian society. Then, the study pays special attention to the way gender roles structure individual accessibility experiences of women and men differently, and, in turn, the way such accessibility experiences take a form of gendered spatiality. Gendered spatiality is examined through the analysis of accessibility space as well as activity space in order to ascertain women's home-attached and spatially entrapped characteristics. More household responsibilities throughout a day and, even more, the time constraint of picking up children at the daycare centers after work lead women's possible activity space to be more home-centered. The analysis of the spatio-temporal context of accessibility space makes gendered spatiality visible. However, the findings suggest that behavioral outcomes should be understood with an explicit awareness of constraints individuals face. It is because the revealed activity spaces can be not only an outcome of constraint but also an outcome of choice. Behavioral outcomes should not be treated as a straightforward expression of the level of constraints. It is problematic to expect that behavioral outcomes directly mirror the level of constraints. It is also problematic to suppose that the level of constraints can be straightforwardly elicited from revealed behavioral outcomes.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.63-74
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• 2006

In order to identify the Pb pollution and its sources in continental shelf and slope areas, Pb concentration and Pb isotope ratios ($^{207}Pb/^{206}Pb\;and\;^{208}Pb/^{206}Pb$) were determined far 6 box corer sediments collected from the southern East/japan Sea. Pb concentration, and $^{207}Pb/^{206}Pb\;and\;^{208}Pb/^{206}Pb$ ratios were constant at around $25\pm5 ppm$ and 0.842 and 2.092 from 1700 to 1930 year, respectively and increased steadily up to $40\pm5 ppm$ and 0.867 and 2.123 at the beginning of 1990s', respectively. The increase of concentration and isotope ratios in the labile fraction (leached by 2M HC1+0.5M $HNO_3$) explains their increase in bulk sediments, while Pb concentration and isotope ratios in the residual fraction were nearly constant during 300yrs. Temporal variation of Pb isotope ratios was explained by simple two end-members mixing of geo-genic and anthropogenic sources because isotope ratios and the inverse of Pb concentration showed the good linear relationships. Using Pb isotope ratios, we can constrain two Pb sources in the study area. The one is atmospheric particulates, compared with mean values of isotope ratios in atmospheric particulates collected at Jeju and Oki ;stands, based on the history of Pb emmission in Korea and China, and judged by oceanographic processes capable of homogenizing many sources. The other is local sources related to iron mills, refineries of Pb ore and of petroleum located at the coast of the study area. Isotope ratios of anthropogenic Pb can be estimated using two end-members mixing equation and were $0.879\pm0.005\;and\;2.144\pm0.008$ before 1950s' while they increased up to $0.900\pm0.008\;and\;2.162\pm0.011$ after 1980s', respectively.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.57-65
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• 2004

In order to determine the effect of fresh water inflow from the Heongsan river on the changes of water quality in the Yeongil Bay (Korea), the seasonal changes of water temperature, salinity, chemical oxygen demand (COD), dissolved inorganic nitrogen(DIN) and phosphate phosphorus ($PO_4$-P) concentrations were examined using the data set obtained five fixed points of Yeongil Bay from 1998 to 2000. The distributions and changes of COD and concentrations of total inorganic phosphorous (TIP) and nitrogen (TIN) at three points Heongsan river, were also compared with those of Yeongil Bay. Based on the correlations of DIN and $PO_4$-P, it was found that the inflow of freshwater affected on the water quality of Yeongil Bay. Such a complicacy was confirmed by the prominent differences in n few water quality measures between Site 1(the innermost area) and Site 5 (the mouth of the bay). The negative correlations in $\Delta N/\Delta P $ at sites 1, 2 and 3 of the inner-part of the bay also indicated a large effect of freshwater inflow on the water quality of the bay. The extremely low atomic ratio of an average of 6.4 in $\Delta N/\Delta P $ compared to the Redfild ratio suggested that the DIN was depleted in the overall bay system. In contrast, it was inferred that the excessive PO$_4$-P concentration was due to the inflow of freshwater from the Heongsan river.