• 한국환경과학회지
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• 제5권2호
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• pp.187-194
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• 1996

The present study was performed to elucidate the distribution of protozoans according to the actual conditions of soil pollution around Ulsan industrial complexes, Korea. Samples were collected from the top-soils of 13 localities in eight times during the period from 16 April 1994 to 14 January 1995. As a result of this study, total 11 species of hypotrichous ciliated protozoa were identified and analyzed. These hypotrichs are 6 species of stichotrichine hyporichs ( Keronopsis sp., Pseudourostyla sp., Hoiriiticha syivatica, Hipiosticha multistylata, Hoios-ticha sp. and ParuroleFitus sp.) and 5 species of sporadotrichine hypotrichs (Oxyricha sp., Steinla sp., Histriculus cavicola, Hemisincirra sp. and Gonostomum auiili). Of these 11 species, 4 species (Keronopsis sp., Pseudourostyla sp., Holosticha sp. and Hemisincirra sp.) are reriorted for 1%e first time from Korea. All the sampling localities could be grouped in three zones by the cluster analysis with the abundance and distribution of protozoans. This result is approximately coincide with the ionation by the concentration of heavy metals.

• Journal of Plant Biology
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• 제33권3호
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• pp.173-182
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• 1990

To investigate the structure of the plant community structure of Mt. Yongmun in Kyonggi-do, fifty-four plots were set up by the clumped sampling method. The classification by TWINSPAN and DCA ordination were applied to the study area in order to classify them into several groups based on woody plant and environmental variables. By both techniques, the plant community were divided into two groups by the aspect. the dominant species of south aspect were Pinus densiflora, Quercus aliena, Q. mongolica, Carpinus laxiflora and of north aspect were Q. ongolica, Fraxinus rhynchophylla. The successional trends of tree species in south aspect seem to be from P. densiflora through Q. serrata, Q. aliena, A. mongolica to C. laxiflora. As a result of the analysis for the relationship between the stand scores of DCA and environmental variables, they had a tendency to increase significantly from the P. densiflora and Q. mongolica community to C. laxiflora and F. rhynchophylla community that was the soil moisture, the amount of soil humus and soil pH.

• Journal of Microbiology and Biotechnology
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• 제23권10호
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• pp.1347-1356
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• 2013

Tricholoma matsutake, an ectomycorrhiza that has mutual relationships with the rootlet of Pinus denisflora, forms a fruiting body that serves as a valuable food in Asia. However, the artificial culture of this fungus has not been successful. Soil fungi, including T. matsutake, coexist with many other microorganisms and plants; therefore, complex microbial communities have an influence on the fruiting body formation of T. matsutake. Here, we report on the structures of fungal communities associated with the fairy ring of T. matsutake through the pyrosequencing method. Soil samples were collected inside the fairy ring zone, in the fairy ring zone, and outside the fairy ring zone. A total of 37,125 sequencing reads were obtained and 728 to 1,962 operational taxonomic units (OTUs) were observed in the sampling zones. The fairy ring zone had the lowest OTUs and the lowest fungal diversity of all sampling zones. The number of OTUs and fungal taxa inside and outside the fairy ring zone was, respectively, about 2 times and 1.5 times higher than the fairy ring. Taxonomic analysis showed that each sampling zone has different fungal communities. In particular, out of 209 genera total, 6 genera in the fairy ring zone, such as Hemimycena, were uniquely present and 31 genera, such as Mycena, Boletopsis, and Repetophragma, were specifically absent. The results of metagenomic analysis based on the pyrosequencing indicate a decrease of fungal communities in the fairy ring zone and changes of fungal communities depending on the fairy ring growth of T. matsutake.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.173-178
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• 2016

Background: In situ gamma spectrometry has been used to measure environmental radiation, assumptions are usually made about the depth distribution of the radionuclides of interest in the soil. The main limitation of in situ gamma spectrometry lies in determining the depth distribution of radionuclides. The objective of this study is to develop a method for subsurface characterization by in situ measurement. Materials and Methods: The peak to valley method based on the ratio of counting rate between the photoelectric peak and Compton region was applied to identify the depth distribution. The peak to valley method could be applied to establish the relation between the spectrally derived coefficients (Q) with relaxation mass per unit area (${\beta}$) for various depth distribution in soil. The in situ measurement results were verified by MCNP simulation and calculated correlation equation. In order to compare the depth distributions and contamination levels in decommissioning KRR site, in situ measurement and sampling results were compared. Results and Discussion: The in situ measurement results and MCNP simulation results show a good correlation for laboratory measurement. The simulation relationship between Q and source burial for the source layers have exponential relationship for a variety depth distributions. We applied the peak to valley method to contaminated decommissioning KRR site to determine a depth distribution and initial activity without sampling. The observed results has a good correlation, relative error between in situ measurement with sampling result is around 7% for depth distribution and 4% for initial activity. Conclusion: In this study, the vertical activity distribution and initial activity of $^{137}Cs$ could be identifying directly through in situ measurement. Therefore, the peak to valley method demonstrated good potential for assessment of the residual radioactivity for site remediation in decommissioning and contaminated site.

• 한국지반공학회논문집
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• 제19권4호
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• pp.43-53
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• 2003

연약점토에 대한 실내시험으로부터 양호한 토질정수를 구하기 위해서는 시료교란의 영향을 최소화하여야만 한다. 본 연구에서는 시료채취기술 및 시료채취관에 따른 시료교란의 영향을 조사하기 위한 목적으로 낙동강 하구유역에 분포하고 있는 연약점성토를 대상으로 한ㆍ일 공동연구를 실시하였다. 양국의 시료채취기술에 의하여 채취된 시료에 대하여 일축압축시험과 압밀시험을 실시하여 토질정수 및 시료교란도를 비교하였다. 결과적으로, 한국에서 사용되고 있는 수압식 피스톤 샘플러를 사용하더라도 시료채취 전에 일본에서 실시하고 있는 방법대로 슬라임의 제거작업을 면밀히 수행할 경우에 시료의 품질이 명백하게 개선됨을 알 수 있었다. 그리고 0.02%/min의 속도로 수행된 일정변형률(CRS) 압밀시험은 표준압밀시험에 비하여 시험방법의 차이 때문에 압밀정수의 증대 및 낮은 교란도를 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1169-1179
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• 2020

In this study, two soybean genotypes, i.e., aluminum-tolerant Baxi 10 (BX10) and aluminumsensitive Bendi 2 (BD2), were used as plant materials and acidic red soil was used as growth medium. The soil layers from the inside to the outside of the root are: rhizospheric soil after washing (WRH), rhizospheric soil after brushing (BRH) and rhizospheric soil at two sides (SRH), respectively. The rhizosphere bacterial communities were analyzed by high-throughput sequencing of V4 hypervariable regions of 16S rRNA gene amplicons via Illumina MiSeq. The results of alpha diversity analysis showed that the BRH and SRH of BX10 were significantly lower in community richness than that of BD2, while the WRH exhibited no significant difference between BX10 and BD2. Among the three sampling compartments of the same soybean genotype, WRH had the lowest community richness and diversity while showing the highest coverage. Beta diversity analysis results displayed no significant difference for any compartment between the two genotypes, or among the three different sampling compartments for any same soybean genotype. However, the relative abundance of major bacterial taxa, specifically nitrogen-fixing and/or aluminum-tolerant bacteria, was significantly different in the compartments of the BRH and/or SRH at phylum and genus levels, indicating genotype-dependent variations in rhizosphere bacterial communities. Strikingly, as compared with BRH and SRH, the WRH within the same genotype (BX10 or BD2) always had an enrichment effect on rhizosphere bacteria associated with nitrogen fixation.

• Geomechanics and Engineering
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• 제23권3호
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• pp.261-273
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• 2020

This paper presents an efficient method utilizing user-defined computer functional codes to determine the reliability of an embankment slope with spatially varying soil properties in real time. The soils' mechanical properties varied with the soil layers that had different degrees of compaction and moisture content levels. The Latin Hypercube Sampling (LHS) for the degree of compaction and Kriging simulation of moisture content variation were adopted and programmed to predict their spatial distributions, respectively, that were subsequently used to characterize the spatial distribution of the soil shear strengths. The shear strength parameters were then integrated into the Geostudio command file to determine the safety factor of the embankment slope. An explicit metamodal for the performance function, using the Kriging method, was established and coded to efficiently compute the failure probability of slope with varying moisture contents. Sensitivity analysis showed that the proposed method significantly reduced the computational time compared to Monte Carlo simulation. About 300 times LHS Geostudio computations were needed to optimize precision and efficiency in determining the failure probability. The results also revealed that an embankment slope is prone to high failure risk if the degree of compaction is low and the moisture content is high.

• 한국토양비료학회지
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• 제46권5호
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• pp.313-321
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• 2013

The Average daily PET (Potential evapotranspiration), evaluated based on the last 30 years meteorological data and the lysimeter experiment carried out by RDA during 11 years, of 9 regions in Korea for the tomato cultivated in greenhouse, was $3.41mm\;day^{-1}$. Two kinds of water saving irrigation standard (WSIS), deficit irrigation standard (DIS) and partial root-zone drying irrigation standard (PRDIS) that include the irrigation interval and the amount of irrigation water according to the region, soil texture and growing stage, were established. According to the DIS and PRDIS, the cultivator can save water up to 29.2% and 53.7%, respectively, for tomato cultivation in greenhouse compared to the full irrigation standard (FIS) which established in 1999. WSIS can be used easily by the cultivator without complicate procedures such as soil sampling and measurement of soil water status by expensive sensors. But the cultivator should care about irrigation method such as PRDI (partial root-zone drying irrigation) without yield decrease.

• 한국지하수토양환경학회지:지하수토양환경
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• 제6권2호
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• pp.31-38
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• 2001

본 연구에서는 사용종료 매립지인 G 매립지를 대상으로 환경질에 대한 평가를 실시하였다. 대상 매립지는 현재 재개발을 위해 공사중에 있는 매립지로서 공사에 앞서 오염도에 대한 정확한 평가가 필요로 할 것이다. 환경질 평가로서 매립지 및 주변 토양, 지하수 그리고 침출수에 대해서 분석하였다. 분석은 현재 기준상에 있는 항목을 위주로 실시하였다. 분석결과 토양시료의 경우 토양오염기준을 만족하였으나 지하수 및 침출수의 경우 일부 항목에서 기준치 이상의 결과를 나타냈다. 따라서 매립지 복원공사시 전체적인 오염도를 고려하여 정화를 하는 노력이 필요할 것으로 판단되어 진다.

• Journal of Microbiology and Biotechnology
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• 제21권4호
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• pp.341-346
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• 2011

To study the effects of salinity-sodicity on bacterial population and enzyme activities, soil samples were collected from the Bay of Yellow Sea, Incheon, South Korea. In the soils nearest to the coastline, pH, electrical conductivity ($EC_e$), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP) were greater than the criteria of saline-sodic soil, and soils collected from sites 1.5-2 km away from the coastline were not substantially affected by the intrusion and spray of seawater. Halotolerant bacteria showed similar trends, whereas non-tolerant bacteria and enzymatic activities had opposite trends. Significant positive correlations were found between EC, exchangeable $Na^+$, and pH with SAR and ESP. In contrast, $EC_e$, SAR, ESP, and exchangeable $Na^+$ exhibited significant negative correlations with bacterial populations and enzyme activities. The results of this study indicate that the soil chemical variables related with salinity-sodicity are significantly related with the sampling distance from the coastline and are the key stress factors, which greatly affect microbial and biochemical properties.