• Economic and Environmental Geology
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• v.43 no.6
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• pp.615-623
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• 2010

Seismic refraction survey is a geophysical method that delineates subsurface velocity structure using direct wave and critically refracted wave. The generalized reciprocal method(GRM) is an inversion technique which uses travel-time data from several forward and reverse shots and which can provide the geometry of irregular inclined refractors and structures underlain by hidden layer such as low velocity zone and thin layer. In this study, a simple Excel-GRM routine was tested for fast mapping of the interface between weathering layer and bedrock during the survey, with employing a pair of forward and reverse shots. This routine was proved to control the maximum dip of approximately $30^{\circ}C$ and maximum velocity contrast of 0.6, based on the panel tests in terms of dipping angle and velocity contrast for the two-layer inclined models. In contrast with conventional operation of five to seven shots with sufficient offset distance and indoor data analysis thereafter, this routine was performed in the field shortly after data acquisition. Depth to the bedrock provided by Excel-GRM, during the field survey for Cheongju granite area, correlates well with the elevation of the surface of soft rock from the drill core and SPS logging data. This cost-effective routine developed for quickly delineating the bedrock surface in the field survey will be readily applicable to mapping of weathering zone in narrow zone with small variation of elevation of bedrock.

• Tunnel and Underground Space
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• v.30 no.1
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• pp.29-38
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• 2020

Recent research trend of North Korean mining and rock engineering in the past 10 years was analyzed by a literature review of mining and rock engineering papers published in North Korean major mining journals, 'mining engineering', 'geological and geographical science' and 'technology innovation' published in 2008-2017. Basic database was established by organizing bibliographic information and abstract data of research papers in each journal. For each journal, paper submission trend classified by research field was analyzed using the basic database. And further study was conducted to the papers which showed distinguishing methodology and result, to analyze the trend of North Korean mining and rock engineering. The literature study showed a recent trend of quantification and automation in mining and rock engineering researches in North Korea, which seems due to recent changes in North Korea's science and technology policy and deterioration of the mining conditions. The results of this study can be applied in the feasibility studies of North Korea's mineral resource development projects. Future inter-Korean technical cooperation and site survey on North Korean field can secure complement the reliability of this study.

• Journal of the Korea Institute of Construction Safety
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• v.1 no.1
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• pp.22-30
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• 2018

Construction accidents in Korea are continuously increasing. Safety signs with high visibility color can diminish such accidents in dangerous places. In order for safety color to be more effective as a global communication means in construction sites, it needs to be checked out whether safety color standard reflect the characteristics of construction industry such as worker or work environment. This paper compared safety color standards among Korea, the US, the UK, and Australia. First, blue color was included in all, which should be corrected considering aged workers increasing in construction industry. Because with age, the ability to distinguish between blue, purple, and gray colors decreases. Second, Korea, which has only single code designated to safety colors, should find alternatives like tolerance to be applicable to a variety of light environments on construction sites, as the contrast which affect the visibility may decrease in dark conditions.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.84-84
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• 2019

본 연구는 전국 임의의 산양삼 재배지를 선정하여 재배지 내의 토양 특성 및 토양세균군집을 분석하고, 토양 특성, 세균군집 및 산양삼 생육특성 간의 상관관계를 구명하기 위하여 수행되었다. 토양 이화학성 분석은 농촌진흥청의 종합분석실 매뉴얼에 따라 분석하였고, 토양세균군집 분석은 pyrosequencing analysis (Illumina platform)를 이용하였다. 토양세균군집과 생육특성 간의 상관관계는 Spearman's rank correlation을 이용하여 분석하였다. 전국 8개 산양삼 재배지로부터 분리한 토양세균군집은 2개의 cluster로 군집화를 이루는 것을 확인하였다. 모든 토양 샘플에서 Proteobacteria와 Alphaproteobacteria가 각각 평균 상대적 빈도수가 35.4%, 24.4%로 우점종으로 나타났다. 나타났다. 두 개의 cluster 간 토양세균군집의 상대적 빈도수를 비교 분석한 결과, 먼저 Proteobacteria (p = 0.03), Actinobacteria (p = 0.02), Ahlpaproteobacteria (p = 0.029), Betaproteobacteria (p = 0.021)는 cluster 1에서 cluster 2에 비해 상대적 빈도수가 유의적으로 높았고, Fimicutes (p = 0.004), Cyanobacteria (p = 0.004), Acidobacteriia (p = 0.041), Ktedonobacteria (p = 0.019), Gammaproteobacteria (p = 0.034), Bacilli (p = 0.009)은 cluster 2에서 유의적으로 상대적 빈도수가 높은 것으로 나타났다. 토양세균군집 cluster 간 산양삼의 생육특성을 비교 분석한 결과, cluster 2 재배지에서 수집한 산양삼 시료의 지하부 생중량은 cluster 1 재배지에서 수집한 산양삼 시료에 비해 cluster 2에서 유의적 (p = 0.04)으로 높았다. 산양삼 생육특성과 토양세균군집 간의 상관관계를 분석한 결과, 산양삼의 생육은 토양 pH가 낮고 Acidobacteria의 상대적 빈도수가 높은 토양에서 증가하였으며, Acidobacteriia와 Koribacteraceae의 상대적 빈도수는 산양삼의 생육과 유의적인 정의 상관관계를 보이는 것으로 나타났다. 본 연구 결과는 토양미생물군집과 산양삼 생육 간의 상관관계를 구명하는 중요한 자료가 될 것으로 생각되고, 나아가 산양삼 재배적지를 선정하는데 있어 보다 명확한 정보를 제공할 수 있을 것으로 사료된다.

• Geophysics and Geophysical Exploration
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• v.6 no.4
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• pp.171-179
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• 2003

In land and marine seismic survey, we generally set receivers with equal interval suppose that sampling interval Is too narrow. But the cost of seismic data acquisition and that of data processing are much higher, therefore we should design proper receiver interval. Spatial aliasing can be occurred on seismic data when sampling interval is too coarse. If we Process spatial aliasing data, we can not obtain a good imaging result. Trace interpolation is used to improve the quality of multichannel seismic data processing. In this study, we applied the Spitz algorithm which is widely used in seismic data processing. This algorithm works well regardless of dip information of the complex underground structure. Using prediction filter and original traces with linear event we interpolated in f-x domain. We confirm our algorithm by examining for some synthetic data and marine data. After interpolation, we could find that receiver intervals get more narrow and the number of receiver is increased. We also could see that continuity of traces is more linear than before Applying this interpolation algorithm on seismic data with spatial aliasing, we may obtain a better migration imaging.

• Journal of Korea Water Resources Association
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• v.54 no.12
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• pp.1295-1304
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• 2021

For the efficient use and management of water resources, a reliable rainfall-runoff analysis is necessary. Still, continuous hydrological data and rainfall-runoff data are insufficient to secure through measurements and models. In particular, as part of the reasonable improvement of a rainfall-runoff model in the case of an ungauged watershed, regionalization is being used to transfer the parameters necessary for the model application to the ungauged watershed. In this study, the GR4J model was selected, and the SCEM-UA method was used to optimize parameters. The rainfall-runoff model for the analysis of the correlation between watershed characteristics and parameters obtained through the model was regionalized by the Copula function, and rainfall-runoff analysis with the regionalized parameters was performed on the ungauged watershed. In the process, the intermediate state variables of the rainfall-runoff model were extracted, and the correlation analysis between water level and the ground water level was investigated. Furthermore, in the process of rainfall-runoff analysis, the Standardized State variable Drought Index (SSDI) was calculated by calculating and indexing the state variables of the GR4J model. and the calculated SSDI was compared with the standardized Precipitation index (SPI), and the hydrological suitability evaluation of the drought index was performed to confirm the possibility of drought monitoring and application in the ungauged watershed.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.184-196
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• 2019

This study aims to extract a 3D image of micro-cracks generated by hydraulic fracturing tests, using the deep learning method and X-ray computed tomography images. The pixel-level cracks are difficult to be detected via conventional image processing methods, such as global thresholding, canny edge detection, and the region growing method. Thus, the convolutional neural network-based encoder-decoder network is adapted to extract and analyze the micro-crack quantitatively. The number of training data can be acquired by dividing, rotating, and flipping images and the optimum combination for the image augmentation method is verified. Application of the optimal image augmentation method shows enhanced performance for not only the validation dataset but also the test dataset. In addition, the influence of the original number of training data to the performance of the deep learning-based neural network is confirmed, and it leads to succeed the pixel-level crack detection.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.513-527
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• 2018

The Tunnel Boring Machine(TBM) is relatively insufficient to cope with unpredicted changes in ground conditions as compared with Conventional Tunnelling Methods. Therefore, it is very important to predict the TBM performance at the design stage and estimate the advance rate for the calculation of the construction period. In this study, we added data to 211 TBM databases constructed in the previous study and analyzed the correlation between TBM outer diameter, maximum thrust, maximum cutterhead torque, cutterhead driving power and RPM, which are the main design and manufacturing specifications of TBM. As a result of the analysis from results obtained in the previous studies, it was confirmed that TBM outer diameter is very effective and important in estimating maximum thrust, maximum cutterhead torque, and cutterhead driving power of the TBM. As a result of comparing the regression equations derived from other TBM databases outside the country and the regression equation obtained from the present study results, the maximum thrust showed a similar tendency to each other, but the maximum torque estimated from the regression equation of this study was higher than that of other countries in the case of the large scale TBM.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.4
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• pp.491-505
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• 2018

As an alternative to deep geological disposal technology, which is considered as a reference concept, the domestic applicability of deep borehole disposal technology for high level radioactive waste, including spent fuel, has been preliminarily evaluated. Usually, the environment of deep borehole disposal, at a depth of 3 to 5 km, has more stable geological and geo-hydrological conditions. For this purpose, the characteristics of rock distribution in the domestic area were analyzed and drilling and investigation technologies for deep boreholes with large diameter were evaluated. Based on the results of these analyses, design criteria and requirements for the deep borehole disposal system were reviewed, and preliminary reference concept for a deep borehole disposal system, including disposal container and sealing system meeting the criteria and requirements, was developed. Subsequently, various performance assessments, including thermal stability analysis of the system and simulation of the disposal process, were performed in a 3D graphic disposal environment. With these analysis results, the preliminary evaluation of the domestic applicability of the deep borehole disposal system was performed from various points of view. In summary, due to disposal depth and simplicity, the deep borehole disposal system should bring many safety and economic benefits. However, to reduce uncertainty and to obtain the assent of the regulatory authority, an in-situ demonstration of this technology should be carried out. The current results can be used as input to establish a national high-level radioactive waste management policy. In addition, they may be provided as basic information necessary for stakeholders interested in deep borehole disposal technology.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.48-48
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• 2019

Amorphophallus paeoniifolius (Dennst.) Nicolson는 영명으로 Elephant yam 또는 Whitespot giant arum 으로 불리는 천남성과(Araceae) 식물로 동아시아, 뉴기니, 오세아니아, 마다가스카르 등지에서 자생하고 있으며 숲의 가장자리 또는 2차림에서 발견 된다. 다년생 식물로 덩이줄기는 어두운 갈색의 둥근모양으로 직경 20~25 cm로 자라고 수염뿌리가 사방으로 달린다. IUCN 적색목록(Red List)에 관심대상 종(LC: Least Concern)에 속하는 식물이다. 현지인들은 마(Dioscorea Polystachya Turcz.)처럼 채소로 먹기도 하며 약용으로 쓰이기도 하는데 복부장애, 소화불량, 천식, 기관지염, 빈혈 등에 약효가 있다. Amorphophallus paeoniifolius은 $25^{\circ}C{\sim}35^{\circ}C$, 연강수량 1,000~1,500 mm에서 잘 자란다. 가운데 눈이 올라오면서 생장을 시작하고 며칠이 지나서야 잎 또는 꽃으로 자라는지 알 수 있다. 잎의 생육주기는 잎눈이 생장을 시작하면 잎자루 끝에 소엽과 소잎자루가 접힌 채로 올라온다. 소엽들이 펴지면서 완전한 모습을 갖추는데 30일 이상의 생장기간을 갖는다. 잎의 형태는 우상복엽(pinnate compound leaf)으로 우산처럼 보이는 잎 하나로 광합성을 한다. 잎은 최대 높이 2.5~3 m, 너비 3 m까지 자라며, 잎자루의 색은 녹색과 청색으로 얼룩덜룩한 무늬가 있다. 인공환경 조건에서 Amorphophallus paeoniifolius 생활사 중 잎의 주기를 연구하기 위해서 광, 온도 등의 지상부 환경은 열대 및 아열대 식물의 자생지와 유사하게 조성하였고, 지하부 환경은 인공 배합토를 사용하여 조성하였다. 평균온도는 $25{\sim}28^{\circ}C$, 겨울철 최저 $16^{\circ}C$, 여름철 최고 $33^{\circ}C$를 유지 관리 하였다. 자동 환경제어시스템으로 온도 및 환기를 유지 관리하고 필요에 따라 수동제어 관리를 병행하여 조절하였다. Amorphophallus paeoniifolius는 잎을 먼저 생성하고 광합성으로 생산된 영양물질을 덩이뿌리에 저장을 하고 그 영양물질을 이용하여 꽃을 피우는 생육 특성을 지닌다. 실험에 사용된 공시 식물은 2018년 12월 미얀마에서 생체(덩이줄기) 형태로 도입되었다. 화분에 식재 후 약 5개월이 지난 시점에서 잎의 생장이 시작되었다. 2019년 7월 29일 기준으로 높이 80 cm, 너비 60 cm의 크기로 성장하였으며, 생육환경에 따라 3~5개월 뒤 잎이 지고 나면 다시 덩이줄기로 되돌아갈 것으로 판단된다. 하지만 지금까지 이 식물에 알려진 정보는 인공환경에서의 연구가 아닌 자연환경에서의 연구결과이기 때문에 인공적인 온실 환경에서 자란 Amorphophallus paeoniifolius는 잎의 주기는 더 오래 갈 수도 있으며 꽃의 주기 또한 느리거나 빠를 수 있다. 잎의 생장주기(Leaf Cycle)시 잎자루가 낮과 밤의 방향을 달리 하여 자라는 것이 관찰되었다. 이는 광합성을 위해서 잎자루의 방향을 햇빛 방향으로 돌리는 것으로 판단된다. Amorphophallus paeoniifolius를 실내 조경 식물 또는 식 약용의 소재식물로 활용하기 위해서는 꽃의 생장주기 등 추가적인 모니터링과 연구가 필요하다.