• Korean Journal of Soil Science and Fertilizer
• /
• v.21 no.4
• /
• pp.386-408
• /
• 1988

A study was conducted to develop a model for estimating evapotranspiration and yield of Chinese cabbages from meteorological factors from 1981 to 1986 in Suweon, Korea. Lysimeters with water table maintained at 50cm depth were used to measure the potential evapotranspiration and the maximum evapotranspiration in situ. The actual evapotranspiration and the yield were measured in the field plots irrigated with different soil moisture regimes of -0.2, -0.5, and -1.0 bars, respectively. The soil water content throughout the profile was monitored by a neutron moisture depth gauge and the soil water potentials were measured using gypsum block and tensiometer. The fresh weight of Chinese cabbages at harvest was measured as yield. The data collected in situ were analyzed to obtain parameters related to modeling. The results were summarized as followings: 1. The 5-year mean of potential evapotranspiration (PET) gradually increased from 2.38 mm/day in early April to 3.98 mm/day in mid-June, and thereafter, decreased to 1.06 mm/day in mid-November. The estimated PET by Penman, Radiation or Blanney-Criddle methods were overestimated in comparison with the measured PET, while those by Pan-evaporation method were underestimated. The correlation between the estimated and the measured PET, however, showed high significance except for July and August by Blanney-Criddle method, which implied that the coefficients should be adjusted to the Korean conditions. 2. The meteorological factors which showed hgih correlation with the measured PET were temperature, vapour pressure deficit, sunshine hours, solar radiation and pan-evaporation. Several multiple regression equations using meteorological factors were formulated to estimate PET. The equation with pan-evaporation (Eo) was the simplest but highly accurate. PET = 0.712 + 0.705Eo 3. The crop coefficient of Chinese cabbages (Kc), the ratio of the maximum evapotranspiration (ETm) to PET, ranged from 0.5 to 0.7 at early growth stage and from 0.9 to 1.2 at mid and late growth stages. The regression equation with respect to the growth progress degree (G), ranging from 0.0 at transplanting day to 1.0 at the harvesting day, were: $$Kc=0.598+0.959G-0.501G^2$$ for spring cabbages $$Kc=0.402+1.887G-1.432G^2$$ for autumn cabbages 4. The soil factor (Kf), the ratio of the actual evapotranspiration to the maximum evapotranspiration, showed 1.0 when the available soil water fraction (f) was higher than a threshold value (fp) and decreased linearly with decreasing f below fp. The relationships were: Kf=1.0 for $$f{\geq}fp$$ Kf=a+bf for f$$I{\leq}Esm$$ Es = Esm for I > Esm 6. The model for estimating actual evapotranspiration (ETa) was based on the water balance neglecting capillary rise as: ETa=PET. Kc. Kf+Es 7. The model for estimating relative yield (Y/Ym) was selected among the regression equations with the measured ETa as: Y/Ym=a+bln(ETa) The coefficients and b were 0.07 and 0.73 for spring Chinese cabbages and 0.37 and 0.66 for autumn Chinese cabbages, respectively. 8. The estimated ETa and Y/Ym were compared with the measured values to verify the model established above. The estimated ETa showed disparities within 0.29mm/day for spring Chinese cabbages and 0.19mm/day for autumn Chinese cabbages. The average deviation of the estimated relative yield were 0.14 and 0.09, respectively. 9. The deviations between the estimated values by the model and the actual values obtained from three cropping field experiments after the completion of the model calibration were within reasonable confidence range. Therefore, this model was validated to be used in practical purpose.

• Applied Biological Chemistry
• /
• v.18 no.3
• /
• pp.123-144
• /
• 1975

This study has been carried out to investigate the translocation-illuviation status of iron and manganese, which are striking phenomena in paddy soils, in relation to its morphological characteristics, and to find out a method to identify illuvial layer of iron quantitatively. Determination of active iron and easily reducible manganese content in surface soils of lowland paddy (266 samples) in Korea were conducted. The examination has been made on relationship between morphological, physico-chemical properties of the representative paddy soils (9 series) and iron and manganese content of their horizons. The results are summarized as follows. 1. The poorer the drainage, the higher concentration of active iron and easily reducible manganese were found, and under same drainage condition, the more the sand, the lower the content of them. 2. Irrespective of soil texture and drainage, highly signignificant positive correlation was found between the contents of active iron ($\hat{Y}$) and clay plus silt in surface soils. $$\hat{Y}=0.3929+(0.05352\;X\;clay%)+(0.0001023\;X\;silt%){\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;I$$ No correlation, however, was found between clay content and easily reducible manganese concentration. 3. Significant positive correlation was obtained between active iron ($\hat{Y}$) and total iron (x) content in each profiles of all soil series. Obtained regression equation is as follows; $$\hat{Y}=0.361x-0.480(r=0.651^{**}){\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;II$$ On the other hand, easily reducible manganese concentration had a tendency to increase, not significantly, with increasing total manganese concentration. 4. Accumulation of iron and manganese generally can be found in paddy soils, but distinct accumulation was found under moderately well drained fine loamy and clay soils, while surface accumulation occurred under poor drainage without regard to soil texture. 5. Profile description or determination of active iron in each horizon were found to be insufficient to designate illuvial layer of iron. Therefore, identification of illuvial layer of iron based on the ratio of total iron and active iron, and concentration of active iron estimated by the content of clay plus silt (Equation 1 above) was thought to be reasonable. Also, manganese accumulation layer would be estimated by total manganese and easily reducible manganese content and their ratio.

• Korean Journal of Soil Science and Fertilizer
• /
• v.18 no.3
• /
• pp.265-275
• /
• 1985

Present studies were carried out to investigate the distribution and formation of organic tiers contained paddy soils in Honam area characteristics to give basic informations on the effective utilization, management and improvement of the soils. The results obtained were summarized as follows; 1. The extent of organic tiers contained paddy soils in Honam area were 6.538㏊ and the amount of peat deposits were presumed about 2.41 million M/T. 2. Out of the total extent of the organic tiers contained paddy soils, about 97.6% was distributed in Honam plains (water-sheds of Mangyeong-Dongjin river), while about 1.5% in the Naju plains (water-sheds of Yeongsan river), and 0.9% in the Wando and Yeocheon areas. 3. The period of peat formation was presumed to be about the early of Seung Moon period (B.C. 4,250), and the Gongdeog series and the Bongnam series were formed in the bog conditions close to the valley mouth of near rolling and hill with small steram channels, and the Gimje series was formed in the out-skirts plains of the Gongdeog and Bongnam soils. 4. In the casue of peat formation, it was presumed to be the Gimje series that accumulated the fibrous peat out of the autochthonous peat such as reeds and grasses etc, to be the Gongdeog and Bongnam series that accumulated the autochtonous peat and the xylem and fibrous peat out of first allochthonous peat. 5. In the Organic horizons of these soils, the range of muck and peat horizons were in 62-68cm and 68-137cm of soil profile in the Gongdeog series, 52-84cm and 84-113cm in the Bongnam series respectively, one of muck horizon was in 46-71cm in the Gimje series. 6. The marks of soil horizons of the soils were expressed that the lower soils than the horizon of muck and peat were formed Cg, Aag for the muck horizon, 0 for the peat horizon, 0 of peat horizon were distingushed with Oag and Oig according to Organic forms. 7. The depthe occurred the muck and peat horizons were positively correlated with the width of local in the Gongdeog series ($r=0.881^{**}$, $r=0.827^{**}$), but not in the Bongnam series and Gimje series.

• Weed & Turfgrass Science
• /
• v.2 no.1
• /
• pp.95-99
• /
• 2013

To investigate the actual condition of production and management of sod, a questionnaire was ask to 57 farmers in major cultivated areas of turf sod in Korea in 2010 and 2011. The results of the turfgrass management situation analysis showed a mixed farming where the ratio of the principal work and the side work progress similarly, and for the landholding type depending on the management scale, the rental ratio was high for a scale over 0.5 ha. Sod production farmers has high-profile in new varieties of turfgrass, integrated management of the fertilization and soil or disease and insect pest however the future of the turfgrass industry does not seem optimistic due to the problems such as market stability or scarcity of worker. Obtaining of information on culture methods depended neighbor's experience (81.8%). Concerning the varieties preference analysis, the 32.1% of farmer answered that the reproductive rate was a key factor for the new variety. Sod production farmers want to receive financial support (28.1%), improvement of distribution structure of sod (26.6%), and spread of good variety turfgrass (23.4%).

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.3
• /
• pp.128-137
• /
• 2013

Due to the global warming and air pollution, interest in renewable energies has increased in recent years. In particular, the crisis of the depletion of fossil energy resources in the near future has accelerated the renewable energy technologies. Among the renewable energy resources, oceans covering almost three-fourths of earth's surface have an enormous amount of energy. For this reason, various approaches have been made to harness the tremendous energy potential. In order to achieve two purposes: to improve harbor water quality and to use wave energy, this study proposed a sea water exchange structure applying an Oscillating Water Column (OWC) wave generation system that utilizes the air flow velocity induced by the vertical motion of water column in the air chamber as a driving force of turbine. In particular, the airflow velocity in the air chamber was estimated from the time variations of water surface profile computed by using 3D-NIT model based on the 3-dimensional irregular numerical wave tank. The relationship of the frequency spectrums between the computed airflow velocities and the incident waves was analyzed. This study also discussed the characteristics of frequency spectrums in the air chamber according to the presence of the structure, wave deformations by the structure, and the power of the water and air flows were also investigated. It is found that the phase difference exists in the time series data of water level fluctuations and air flow in the air chamber and the air flow power is superior to the fluid flow power.

• Journal of Life Science
• /
• v.21 no.10
• /
• pp.1473-1480
• /
• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Microbial removal of perchlorate is the method of choice since microorganisms can reduce perchlorate into harmless end-products. Such microorganisms require an electron donor to reduce perchlorate. Conventional perchlorate-removal techniques employ heterotrophic perchlorate-reducing bacteria that use organic compounds as electron donors to reduce perchlorate. Since continuous removal of perchlorate requires a continuous supply of organic compounds, heterotrophic perchlorate removal is an expensive process. Feasibility of autotrophic perchlorate-removal using elemental sulfur granules and activated sludge was examined in this study. Granular sulfur is relatively inexpensive and activated sludge is easily available from wastewater treatment plants. Batch tests showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of granular sulfur as an electron donor. Perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as the perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of sulfur particles were used for the autotrophic perchlorate-removal, suggesting that sulfur particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of the biofilm sample obtained from enrichment culture that used sulfur particles for $ClO_4^-$-degradation.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.13 no.6
• /
• pp.11-25
• /
• 2009

A method of instrumentally estimating the seismic intensity (MMI) based on Fourier Acceleration Spectrum, which is the so-called 'FAS MMI method' of Sokolov and Wald (2002), was considered for its applicability to Korea. In order to implement the FAS MMI method, the empirical models of mean (m) and standard deviation (${\sigma}$) for Korea were derived for MMI ${\leq}$ IV according to individual seismic intensity by using the site-consistent horizontal FAS of 580 records from 65 isoseismal maps prepared based on the reported MMI of Korea Meteorological Administration. The site-consistent FAS at a site were obtained by correcting the observed FAS for the difference of the site amplification function relative to that of the target site of Class D station (Yun and Suh, 2007) which was evaluated to be a representative site for the generic soil profile of Korea. The FAS m model for MMI ${\leq}$ IV follows the overall linear relation in log space according to seismic intensities, featuring the FAS mean model for MMI = IV similar to that of the global model of Sokolov and Wald (2002). The ${\sigma}$-values of the FAS model are found to be greater than those of the global model for MMI ${\geq}$ V, while significantly lower than those of the global model for MMI = IV.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.17 no.3
• /
• pp.160-174
• /
• 2014

The purpose of this paper is to develop a meso-scale grid-based continuous hydrological model and apply to assess the future watershed hydrology by climate change. The model divides the watershed into rectangular cells, and the cell profile is divided into three layered flow components: a surface layer, a subsurface unsaturated layer, and a saturated layer. Soil water balance is calculated for each grid cell of the watershed, and updated daily time step. Evapotranspiration(ET) is calculated by Penman-Monteith method and the surface and subsurface flow adopts lag coefficients for multiple days contribution and recession curve slope for stream discharge. The model was calibrated and verified using 9 years(2001-2009) dam inflow data of two watersheds(Chungju Dam and Soyanggang Dam) with 1km spatial resolution. The average Nash-Sutcliffe model efficiency was 0.57 and 0.71, and the average determination coefficient was 0.65 and 0.72 respectively. For the whole Han river basin, the model was applied to assess the future climate change impact on the river bsain. Five IPCC SRES A1B scenarios of CSIRO MK3, GFDL CM2_1, CONS ECHO-G, MRI CGCM2_3_2, UKMO HADGEMI) showed the results of 7.0%~27.1 increase of runoff and the increase of evapotranspiration with both integrated and distributed model outputs.

• Journal of Korean Society of Forest Science
• /
• v.81 no.4
• /
• pp.303-309
• /
• 1992

This study eras carried out to investigate the ecological changes on the plant community at erosion controlled area in Yoju-gun, Kyonggi-do. The results of the study were as follows : 1. The depth of organic matters in the soil profile from 4 to 14 years was estimated to be $Y_{(cm)}=0.436X_{(yr)}-0.931$(r=0.978), and 02 layer was $Y_{(cm)}=0.339_{(yr)}-0.931$ (r=0.954). 2. On upper plant layer. Alnus spp. was decreased, on an average, 32% of relative coverage, 12.4% of relative density and 16.8% of relative frequency in each plot for 3 years, as this area was damaged by Agelastica coerulea Baly for 2-3 years. 3. On upper plant layer, relative coverage of Pinus spp. was increased after 6, 7 years in erosion controlled area and was taked the highest plant (more then 40%) from 10 to 14 years. 4. On lower plant layer, relative density of Quercus ssp. (these species has not been planted and sown on erosin controlling) was increased all the plot. 5. The increase of the whole crown projection area was estimated to be $Y_{(m^2)}=18.020X_{(yr)}+18.834$(r=0.954) 6. The biomass was estimated to be 14.88t/ha on elapsed 6 years, 22.84t/ha on 8 years, 35.08t/ha on 10 years, 47.80t/ha on 12 years, 58.13t/ha on 14 years.

• Journal of Microbiology and Biotechnology
• /
• v.13 no.6
• /
• pp.960-968
• /
• 2003

A bacterial isolate showing a strong endochitosanase activity was isolated from soil and then characterized. The isolate was identified and designated as Bacillus cereus P16, based on morphological and biochemical properties, assimilation tests, cellular fatty acids pattern, along with 16S rRNA gene sequence. The optimized medium for producing extracellular chitosanase in a batch culture contained 1% tryptone, 0.5% chitosan, and 1% NaCl (pH 7.0). Powder chitosan and tryptone served the best as carbon and nitrogen sources, respectively, for the chitosanase production. Chitosanase activity was the highest when culture was completed at $37^{\circ}C$ among various temperatures ($20-42^{\circ}C$) tested in a shaking incubator (200 rpm). The levels of chitosanase activity in the culture fluid were 2.0 U/ml and 3.8 U/ml, respectively, when incubated in a flask for 60 h and in a jar fermenter for 24 h. The culture supernatant showed a strong liquefying activity on the soluble chitosan. The viscosity of 1% chitosan solution, that was incubated with the culture supernatant, was rapidly decreased, suggesting the secretion of endochitosanolytic enzymes by P16. The culture fluid revealed six endo-type chitosanase isozymes, two major (38 and 45 kD), and four minor (54, 65, 82, and 96 kD) forms by staining profile. The crude enzymes were very stable, and full activity was maintained for 4 weeks at $4^{\circ}C\;or\;-20^{\circ}C$ in the culture supernatant, suggesting a highly desirable stability rate for making an industrial application of the crude enzymes. The supernatant also cleaved the insoluble chitosan powder, but the hydrolysis rate was much lower. The enzymic degradation products of chitosan contained $(GlcN)_n$ (n=2-8). The concentration of chitosan in the reaction mixture of the crude enzyme affected the chitooligosaccharides composition of the hydrolysis products. When the higher concentration of chitosan was used, the higher degree of polymerized chitooligosaccharides were produced. By comparison with other commercial chitosanase preparations, P16 was indeed found to be a valuable enzyme source for industrial production of chitooligosaccharides from chitosan.