• The Korean Journal of Quaternary Research
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• v.13 no.1
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• pp.35-43
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• 1999

Goryeri archaeological site is located in the upstream valley of the Danjang River. The basement rocks of the area are composed of the Cretaceous to Palaeogene biotite granite (KbGr), acidic dyke (Kad), Milyang Andesite (Kma) and Jyunggagsan Formation. Among them Milyang Andesite and Jyunggagsan Formation are prevailed in archaeological site and they are composed of reddish brown tuffaceous shale, sandstone and conglomerate, with intercalations of acidic tuffs and lapilli tuffs. The purpose of this research is not only to compare REE pattern of the soil-sedimentary deposits with those of surrounding rocks, but also to identify vitric tephra in the soil-sedimentary deposits derived from the andesite, acidic tuff and lapilii tuff, in order to illucidate the provenance of the vitric tephra. The rare earth element(REE) of the soils and sedimentary deposits results in the same REE pattern with those analyzed from the surrounding basement rocks. This indicates that the soils and sedimentary deposits are originated from the surrounding basement rocks, most probably from the andesite and lapilli tuff. In addition, vitric tephra were identified both in the Quaternary in-situ weathered soils and sedimentary deposits (PMU-13 and PMU-17), and in the weathered surrounding lapilli tuff. These vitric tephra are considered to be different from those of Japanese AT(Aira Tanzawa) -tephra. The latter is predominant with clean, platty, bubble-walled and Y-shaped vitrics, while the former is conspicuous with those shapes of large and diverse size and devitrified, as well as having secondarily bubbled-surfaces reflecting surface weathering. The size of vitric fragments in the Goryeri site is about 300${\mu}{\textrm}{m}$ and large in size in compasion to 150${\mu}{\textrm}{m}$ of Japanese AT-Tephra. The interim results of the research are contradictary to the explanations based on a series of AT-tephra researches carried by Japanese scholar. In short, the vitric materials of the Goryeri archaeological site are most probably originated from the weathering products of the surrounding basement rocks, and are different from the AT-tephra in their size, shape and devitrification properties. Thus it is highly recommended to have a further comprehensive research which is more emphasized the magmatic genesis of these vitric tephra in addition to the external shape and morphology.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.883-893
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• 2019

In this study, crop coefficients were calculated in two different methods and the results were evaluated. In the first method, appropriateness of GLDAS-based evapotranspiration was evaluated by comparing it with observed data of Cheongmi-cheon (CMC) Flux tower. Then, crop coefficient was calculated by dividing actual evapotranspiration with potential evapotranspiration that derived from GLDAS. In the second method, crop coefficient was determined by using MLR (Multiple Linear Regression) analysis with vegetation index (NDVI, EVI, LAI and SAVI) derived from MODIS and in-situ soil moisture data observed in CMC, In comparison of two crop coefficients over the entire period, for each crop coefficient GLDAS K_c and SM&VI K_c, shows the mean value of 0.412 and 0.378, the bias of 0.031 and -0.004, the RMSE of 0.092 and 0.069, and the Index of Agree (IOA) of 0.944 and 0.958. Overall, both methods showed similar patterns with observed evapotranspiration, but the SM&VI-based method showed better results. One step further, the statistical evaluation of GLDAS K_c and SM&VI K_c in specific period was performed according to the growth phase of the crop. The result shows that GLDAS K_c was better in the early and mid-phase of the crop growth, and SM&VI K_c was better in the latter phase. This result seems to be because of reduced accuracy of MODIS sensors due to yellow dust in spring and rain clouds in summer. If the observational accuracy of the MODIS sensor is improved in subsequent study, the accuracy of the SM&VI-based method will also be improved and this method will be applicable in determining the crop coefficient of unmeasured basin or predicting the crop coefficient of a certain area.

• Korean Journal of Environment and Ecology
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• v.35 no.1
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• pp.68-80
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• 2021

This study aimed to provide basic data such as the structure of the Carpinus turczaninowii community and characteristics of the habitat environment for ex situ conservation by analyzing the plant community structure of Carpinus turczaninowii, an island plant resource. For the community structure analysis, this study established 29 plots, sized 100㎡ each, in Seokmo, Yeongjong, Yeongheung, and Daebu islands. TWINSPAN was used for the classification of communities. The classification identified six communities. Group I was the C. turczaninowii-Quercus serrata community, group II was the C. turczaninowii-Pinus densiflora community, group III was the C. turczaninowii-Quercus mongolica community, group IV was the C. turczaninowii-Sorbus alnifolia community, group V was the C. turczaninowii typical community, and group VI was the C. turczaninowii-Quercus variabilis community. The species diversity was 0.90008~1.12868, the dominance was 0.17536~0.25665, and the similarity index was 17.1429~38.2979%. The result of correlation analysis of 7 environmental factors for 6 communities by RDA ordination showed a positive correlation between the crown density and litter layer and a negative correlation between the bare rock, soil hardness, and altitude on the 1st axis. On the 2nd axis, the bare rock and crown density showed a positive correlation, and the slope showed a negative correlation. In the C. turczaninowii-Quercus serrata community (I), the crown density and the litter layer were the environmental factors affecting the vegetation distribution. In the C. turczaninowii-Pinus densiflora (II) and C. turczaninowii-Quercus mongolica (III) communities, the slope was the factor affecting vegetation distribution. In the C. turczaninowii-Sorbus alnifolia (IV), C. turczaninowii typical (V), and C. turczaninowii-Quercus variabilis (VI) communities, the bare rock, altitude, and soil hardness were the factors affecting vegetation distribution.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.5-16
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• 2012

In the case of using the soil materials created by cutting in-situ ground directly without adjusting particle size, it is recommendable to seek the compaction property or material constant required for filling design or density control through indoor test, and many studies on this subject have been carried out during that time. The researches conducted during that time, however, were focused on the mixed materials with different diameters that exist in a natural condition. There has been no study conducted using coal fly ash that is by-product of the thermal power plant that is actively considered as the building materials. Therefore, this study was aimed at implementing compaction test and examining the basic engineering property in order to explore the influence of crushing the particles through compacting the admixture of crushed stone and coal fly ash produced from thermal power plant on its engineering property, and then the impact of the admixture volume of each material on compaction property and material property by conducting the One-Dimensional Compression Test. As result of compaction test, the optimum moisture ratio of coal fly ash was shown to be approx. 23%. As result of compaction test in accordance with the mixed ratio of coal fly ash and crushed stone under the same compaction energy and moisture ratio, dry unit weight tended to drop when the mixed ratio of coal fly ash exceeded 30%, while it reached approx. $1.81gf/cm^3$ when the mixed ratio was 30%. As result of One-Dimensional Compression Test in accordance with the mixed ratio of crushed stone and coal fly ash, the change in void ratio by particle crushing was at the highest level in the case of coal fly ash 100%, while the lowest level in the case of crushed stone 100%. In the case of mixed materials of crushed stone and coal fly ash, compression index was at the lowest level in case of coal fly ash 30%, and therefore this ratio of mixed material was judged to be the most stable from an engineering aspect.

• Economic and Environmental Geology
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• v.42 no.4
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• pp.315-333
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• 2009

In this study, the hydrochemical and the isotopic characteristics of major streams in the Daejeon area were investigated during rainy and dry seasons. The stream water shows the electrical conductivity of the range of $37{\sim}527{\mu}s$/cm, and pH $6.21{\sim}9.83$. The chemical composition of stream waters can be grouped as three types: the upper streams of Ca(Mg)-$HCO_3$ type, Ca(Mg)-$SO_4(Cl)$ type of middle streams flowing through urban area, and Na(Ca)-$HCO_3$(Cl, $SO_4$) type of the down streams. Based on in-situ investigation, the high pH of stream waters flowing through urban area is likely to be caused by the inflow of a synthetic detergent discharging from the apartment complex. The electrical conductivity of stream waters at a dry season is higher than those of at a rainy season. We suggest that the hydro-chemical composition of stream waters in the Daejeon area was affected by the discharging water from the sewage treatment facilities and anthropogenic contaminants as well as the interaction with soil and rocks. ${\delta}D$ and ${\delta}^{18}O$ values of the stream waters show the relationship of ${\delta}D=6.45{\delta}^{18}O-7.4$, which is plotted at a lower area than global meteoric water line(GMWL) of Craig(1961). It is likely that this isotopic range results from the evaporation effect of stram waters and the change of an air mass. The isotope value shows an increasing trend from upper stream to lower stream, that reflects the isotopic altitude effect. The relationship between ${\delta}^{13}C$ and $EpCO_2$ indicates that the carbon as bicarbonate in stream water is mainly originated from $CO_2$ in the air and organic materials. The increasing trend of ${\delta}^{13}C$ value from upper stream waters to lower stream waters can be attributed to the following reasons: (1) an increasing dissolution of $CO_2$ gas from a contaminated air in downtown area of the Daejeon, and (2) the increment of an inorganic carbon of groundwater inflowed into stream by base flow. Based on the relationship between ${\delta}^{34}S$ and $SO_4$ of stream waters, the stream waters can be divided into four groups. $SO_4$ content increases as a following order: upper and middle Gab stream${\delta}^{34}S$ value decreases as above order. ${\delta}^{34}S$ value indicates that sulfur of stream waters is mainly originated from atmosphere, and is additionally supplied by pyrite source according to the increase of sulfate content. The sulfur isotope analysis of a synthetic detergent and sewage water as a potential source of the sulfur in stream waters is furtherly needed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.45-53
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• 2006

The objectives of this study are to determine the primary yield components responsible for yield differences in a subtropical environment of the Hunan province China and in a temperature environment of Honam province Korea. Field experiments were conducted in a subtropical environment in Hunan province China during 2002 and in a temperate environment in Honam province Korea during 2003. Seven rice cultivars were grown under optimum crop management in each experiment field. Yield, yield components and plant dry matter were determined at maturation. The highest yield (567 kg/10a) was produced at Honam province by Jinyou 207, a Chinese cultivar, The maximum yield at Hunan province was 453 kg/10a by Sanyou 63. On the average across cultivars, Honam produced 23% greater yields than Hunan. Sink size (spikelets per $m^2$) was responsible far these yield differences. Panicle number per $m^2$ was much greater at Honam.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.63-74
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• 2006

During the construction of circular underground pipe, the non-proper compaction along the pipe and the decrease of compaction efficiency have been the main problems to induce the failure of underground pipe or facility. The use of CLSM (controlled low strength materials) should be one of the possible applications to overcome those problems. In this research, the full-scaled field test and the numeric analysis using PENTAGON-3D FEM program were carried out for three different cases on the change of backfill materials, including the common sand, the soil from construction site, and the CLSM. From the full-scaled test in field, the use of in-situ CLSM as backfill materials reduced the vertical and lateral deformation of the pipe, as well as the deformation of the ground surface. The main reason for reducing the deformation would be the characteristics of the CLSM, especially self-leveling and self-hardening properties. The measured earth pressure at the surround of the corrugated pipe using the CLSM backfills was the smaller than the other cases, and the absolute value was almost zero. Judging from the full-scaled field test and FEM analysis, the use of CLSM as backfill materials should be one of the best choices reducing the failure of the underground pipes.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1465-1483
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• 2020

Evapotranspiration is a concept that includes the evaporation from soil and the transpiration from the plant leaf. It is an essential factor for monitoring water balance, drought, crop growth, and climate change. Actual evapotranspiration (AET) corresponds to the consumption of water from the land surface and the necessary amount of water for the land surface. Because the AET is derived from multiplying the crop coefficient by the reference evapotranspiration (ET0), an accurate calculation of the ET0 is required for the AET. To date, many efforts have been made for gridded ET0 to provide multiple products now. This study presents a comparison between the ET0 products such as FAO56-PM, LDAPS, PKNU-NMSC, and MODIS to find out which one is more suitable for the local-scale hydrological and agricultural applications in Korea, where the heterogeneity of the land surface is critical. In the experiment for the period between 2016 and 2019, the daily and 8-day products were compared with the in-situ observations by KMA. The analyses according to the station, year, month, and time-series showed that the PKNU-NMSC product with a successful optimization for Korea was superior to the others, yielding stable accuracy irrespective of space and time. Also, this paper showed the intrinsic characteristics of the FAO56-PM, LDAPS, and MODIS ET0 products that could be informative for other researchers.