• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.386-386
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• 2017

지하수 해석을 위해 3차원 수치해석 모형이 적용되고 있으나, 다양한 매개변수를 명확히 적용하기에는 한계가 있다. 특히, 수리전도도는 지층의 투수성정도를 나타내는 계수로 지하수 분석에 매우 중요한 매개변수이다. 신뢰성의 확보를 위해 양수시험을 통해 산출된 결과를 이용하고 있으나 소수관정의 시험결과를 유역의 대푯값으로 적용하기에 불확실도가 매우 높고, 수위변화가 독특한 지역의 정확한 수리특성을 적용하기에 한계가 있다. 이 연구에서는 수리전도도 특성을 해석하기 위하여 3차원 수치해석모형을 적용하였으며, 모델보정 방법 중 Regularization(정규화)라고 불리는 Pilot point 기법을 사용하였다. 제주도와 같이 수리전도도 값이 지역별로 차이가 크고 동일 유역 내에도 다른 지질구조를 보이는 등 동일 매질에서 동일 투수성을 보이지 않는 다양함으로 실측값들을 적용하기에 어려운 곳에서 정규화라는 보정방법은 최적화된 방법이다. 지하수위는 중제주유역 내 위치한 12개소 수위관측정의 2016년 연평균수위를 적용하였다. 미계측지역은 제주도 등수위선자료를 이용하여 DEM을 구축하였으며, 임의지점 17개소를 선정하여 대표수위로 적용하였다. 중제주유역의 평균 수리전도도는 82.90 m/day로 분석되었으며, 유역의 동측 하류부는 최대 1,745 m/day로 비교적 큰 결과가 산출되었다. 유역의 중앙에 위치하는 OR관측정을 기준으로 동 서지역의 지하수위를 검토한 결과 서측은 지형구배에 따라 지하수위가 형성하고 있으나, 동측의 경우 상 하류의 표고차가 30m이상 발생되지만 지하수위는 유사한 형태를 보이고 있다. 지하수 흐름에 해석되는 Darcy의 방정식은 수리전도도와 동수경사는 반비례관계를 나타내며, 이 이론에 의해 상 하류 지하수위가 유사하게 형성되는 동측지역은 국부적으로 수리전도도가 높게 형성되는 것으로 확인되었다. 실무에서는 유역경계에 따라 평균화된 매개변수가 적용되므로 명확한 지하수 해석이 어렵고, 수리전도도와 같이 지역적 편차가 심한 매개변수는 다양한 연구를 통해 적용성검토가 수행되어야 한다.

• Korean Journal of Remote Sensing
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• v.16 no.1
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• pp.13-24
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• 2000

SAR imagery usually reveals the influence of antenna look-direction on the delineation of geological structures. In this study, the look-direction bias in SAR image is quantitatively analyzed specifically for geological lineament study. Geologic lineaments are estimated using both Landsat TM and JERS-1 SAR images over the study area to quantitatively compare and analyze the look-direction bias in the SAR image. The standard geologic lineaments in the study area are established from lineaments estimated from TM images, field mapping, and fault lines in a published geologic map. The results show that lineaments normal to radar look-direction are extremely well enhanced while those parallel to look-direction are less visible as expected. However, certain lineaments even parallel to radar look-direction can still be detectable in a favorable topographic condition. Compared with TM image, the total number of detected lineaments in each direction in the SAR image increases or decreases ranging from 33% to 159% in length and from 28% to 187% in occurrence. The ratio of lineaments in SAR image to those in TM image with respect to direction can be fitted by a cosine function. The fitted function indicates that geological lineament is more easily detected in SAR image than in TM image within about $\pm$50$^{\circ}$ normal to radar look-direction. And lineaments with limited extension appear to be more sensitive to the look direction bias effect.

• Economic and Environmental Geology
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• v.41 no.2
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• pp.243-252
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• 2008

The Iho and Hamdeok beaches, the major coastal beaches in Jeju Island, have been studied through size analysis and using an experimental extension pole and sediment trap in beach profile, in order to understand their textural characteristics, migration patterns, and seasonal change in beach geometry. The Iho beach is composed of coarse and medium sands, 590 m in total length. The foreshore slope is 12.3$^{\circ}$ in summer and 10.8$^{\circ}$ in winter, which shows more steeper in summer. The Hamdeok beach consisting mostly of shell fragments is 950 m long, $5.7{\sim}7.4^{\circ}$ steep and 97.4${\sim}$114.5 m wide, respectively. The suspended load drift concentrations in the studied beaches showed 4.5 mg/l during the period of summer and 33.2 mg/l in winter, and those of fine-grained sediments are derived mostly from the marine of northeastward direction. The typical beach transformation of the Iho beach is resulting from the construction of jetties in the west side that built up the sand inside the jetties, whereas the erosion is occurring on the east side of beach. The center and berm sides of the sand in the Hamdeok beach drift into the dune side during the period of the stormy winter season.

• Journal of the Korean association of regional geographers
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• v.10 no.4
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• pp.727-743
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• 2004

This paper aims to explore the geographic characteristics of ecotour resources in Gumho-river basin and to study the educational application of ecotour resources. To grasp the characteristics of ecotour resources in Gurnho-basin, this research carried out a literature review about Gumho-river basin and arranged ecotour resources by different types. Ecotour resources are divided into geomorphic and geologic resources, plant communities, wildlife habitats, cultural and historical resources, regional events with eco-resources. The case studies of New Zealand present good examples of how to successfully use the ecotour goals as a educational applications to Korea. The ecotourism in Korea has not still achieved the real benefits which meet environmental conservation, regional economic advantages and educational effects. Thus, the ecotour programmes should be include entrance limitations, strict opening time schedules, natural trails, museums for study, boards for study, well trained information officers and guides organized by residents. In addition, the local residents prepare of winter programmes for sustainable economic advantages.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.2
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• pp.59-66
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• 2018

This study examined the correlation among topography, forest type, soil and geology in Inje area where landslides occurred during heavy rainfall from July 11 to July 18, 2006 to assess the landslide susceptibility. In order to assess the susceptibility of future landslides, landslides occurred in Inje area were classified into slide type and flow type, and slope angle, aspect, curvature, ridge and valley were extracted from the area. The landslide susceptibility was assessed by applying diameter class, age class, density, and forest type to Bayesianbased LR (Logistic Regression) model and WOE (Weight of Evidence) model, and the fitness of modeling was verified by predict rate curve. As the results of susceptibility assessment, using all landslides without no distintion, it was found that 75% of the LR model and 73% of the WOE model were fit in terms of the top 20% of the landslides. According to slide type and flow type in the top 20% of the landslides, it was found that 71% of the LR model and 69% of the WOE model were fit in terms of the slide type. Whereas, it was found that 86% of the LR model and 82% of the WOE model were fit in terms of the flow type. That is, the results of the LR model showed higher fitness than the results of the WOE model, and the fitness of the flow type was higher than that of the slide type. Consequently, it suggests that it is reasonable to assess and verify the landslide susceptibility according to the types of landslides.

• Economic and Environmental Geology
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• v.40 no.3 s.184
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• pp.295-306
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• 2007

In this study, we predicted areas vulnerable to ground subsidence near abandoned underground coal mine at Sam-cheok City in Korea using a probability (frequency ratio) model with Geographic Information System (GIS). To extract the factors related to ground subsidence, a spatial database was constructed from a topographical map, geo-logical map, mining tunnel map, land characteristic map, and borehole data on the study area including subsidence sites surveyed in 2000. Eight major factors were extracted from the spatial analysis and the probability analysis of the surveyed ground subsidence sites. We have calculated the decision coefficient ($R^2$) to find out the relationship between eight factors and the occurrence of ground subsidence. The frequency ratio model was applied to deter-mine each factor's relative rating, then the ratings were overlaid for ground subsidence hazard mapping. The ground subsidence hazard map was then verified and compared with the surveyed ground subsidence sites. The results of verification showed high accuracy of 96.05% between the predicted hazard map and the actual ground subsidence sites. Therefore, the quantitative analysis of ground subsidence near abandoned underground coal mine would be possible with a frequency ratio model and a GIS.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.3
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• pp.116-124
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• 2000

Geochemical and isotopic analyses were carried out to investigate hydrochemical characteristics, source of carbon species in the carbonated waters in South Korea. Most Korean carbonated waters from different geologic settings are characterized by a Ca-HCO$_3$type with a relatively low pH range from 5.3 to 6.3 (avg. 6.0). The concentrations of cations and anions in the carbonate waters are in the order of Ca$^{2＋}$>Na$^{＋}$>Mg$^{2＋}$>Si$^{4＋}$>Fe$^{2＋}$>K$^{＋}$ and HCO$_3$$^{－}$>SO$_4$$^{2－}$>Cl$^{－}$, respectively. The HCO$_3$$^{－}$ ion is more enriched in the carbonated water from the sedimentary rock and granitic rock of Mesozoic age in the Gyungsang basin(GII) and the Precambrian metamorphic rock and Jurassic granitic rocks of the Gyunggj massif in the Gangwon province(GⅠ) than those of the meta-sedimentary rock and granite in the Ogcheon zone(GⅢ). Based on the oxygen and hydrogen isotopic data, the carbonated waters are derived from the meteoric water, showing apparent latitude and altitude effects. The $delta$$^{13}$C values of carbon species in the carbonated water are in between -6.23 and 0.0 $textperthousand$, suggesting inorganic source of carbon originated from the carbonate mineral and carbonate rock in the aquifer.

• Journal of Korean Society of Forest Science
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• v.113 no.1
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• pp.14-30
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• 2024

This study characterized areas at risk of land creep by focusing on a site that has undergone this phenomenon in Ulju-gun, South Korea. Land creep in the area of interest was catalyzed by road expansion work conducted in 2022. The site was examined on the basis of its geological features, topography, effective soil depth, soil hardness, electrical resistivity, and subsurface profile. It consists of a slope covered with sparse vegetation and a concave top that retains rainwater during rainfall. Compositionally, land creep affected the shale, sandstone, and conglomerate formations on the site, which had little silt and more sand and clay compared with areas that were unaffected by land creep. An electrical resistivity survey enabled us to detect a groundwater zone at the site, which explains the softness of the soil. Finally, the effective soil depth at the land creep-affected area was 30.4 cm on average, indicating deep colluvial deposits. In contrast, unaffected sites had an effective soil depth of 24.7 cm on average. These results should facilitate the creation of systems for monitoring and preemptively responding to land creep, significantly mitigating the socioeconomic losses associated with this phenomenon.

• Journal of Marine Life Science
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• v.8 no.1
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• pp.68-77
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• 2023

In this study, we investigated the quantitative distribution of microplastics in the surface seawater at 8 points near the Taean Peninsula using fluorescence staining. The study revealed a detection range of microplastics from 0 to 360.5 particles/l, with an average of 149.7 ± 46.0 particles/l. When classifying the microplastics by size, it was found that particles smaller than 50 ㎛ were dominant, although there were differences at Site 3. Moreover, it was not possible to identify clear correlations when comparing the number of microplastics based on collection area and particle size. Various physical and chemical factors, including plastic material, dynamic ocean conditions (such as currents, wind, waves, tides), geological characteristics (topography, slope), sediment materials including coastal organisms, human activities (fishing, development, tourism), and weather conditions (floods, rainfall), affect the behavior of microplastics. Therefore, future efforts should focus on standardizing quantitative analysis methods and conducting fundamental research on microplastic monitoring, including the analysis of environmental factors.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.156-166
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• 2000

This study was carried out to provide the information on seasonal variations of water content under highway asphalt pavements which influence on the dynamic behaviour and durability of pavements, and to assess the correlation between water content and soil or meteorological factors. Total eight sites for water content measurement which included fives sites in Kyungbu, two sites in Honam, and one site in Youngdong Highway were selected considering the variations in geology, topology and meteorology factors over all the country. Water contents under asphalt pavements were measured up to 170 cm depth every two week for total 13 months of August 1992 through September 1993 using neutron moisture meter(CPN-503DR). The range of water content ($\theta$$_{w}$) at the upper soils of above 50 cm depth was 7~12% and was not quite different regardless of sites, except for Iseo site. However, soil water contents below 60 or 70 cm depth were significantly different between the measurement sites, that is, the lowest water content was 5% at Kyungsan site and the highest water content was 20% at Iseo site. For all the sites, seasonal variations in water content during the experimental period were little, their range was within only 1 to 4%. Seasonal variations of water content in original or cutting area, which were 4% more or less, were slightly larger than in bedding areas, which were below 2%. Water contents under asphalt pavements had statistically significant positive correlations with silt and clay content in soil, but there were little correlations between water content and meteorological factors such as precipitation, relative humidity, mean air temperature, and wind velocity.