• Title/Summary/Keyword: Mountain slope

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Characteristics of Nocturnal Atmospheric Cooling on a Mountain Slope (산지 경사면의 야간 대기 냉각 특성)

  • 황규홍;이정택;허승오;심교문
    • Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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    • 2001.06a
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    • pp.68-71
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    • 2001
  • 밝고 바람이 없는 저녁, 지표근처의 냉각은 많고 일출 전후에 최저기온이 나타난다(Nishiyama, 1985). 그리고 기온은 지표근처에서 가장 낮고 고도가 높아질수록 높아진다. 이러한 상태를 지표역전(surface inversion) 또는 지면역전(ground inversion)이라 한다. 지표 역전층은 지표근처에 강한 복사냉각(radiative cooling)에 의해 형성되고, 다른 하나는 차가운 공기의 drainage에 의해 이류(advection) 되어 지표근처에 축적된다.(중략)

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A Proposal for Risk Evaluation Method of Slope Failure due to Rainfalls (강우 시 사면 붕괴 위험도 평가에 관한 제안)

  • Chae, Jong-Gil;Jung, Min-Su;Tori, Nobuyaki;Okimura, Takashi
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.893-903
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    • 2008
  • A method for predicting surface failures which occur during heavy rainfall on mountain slopes is proposed by using the digital land form model that is obtained by reading altitude on a topographical map at 10m grid point space. A depth of a potential failure layer is assumed at each grid point. In the layer, an infiltrated water movement from cell to cell is modeled in the study (cell is a square of the grid). Infiltrated ground water levels which show the three dimensional effects of a topographical factor in an area can be hourly calculated at every cell by the model. The safety factor of every cell is also calculated every hour by the infinite slope stability analysis method with the obtained infiltrated ground water level. Failure potential delineation is defined here as the time when the safety factor becomes less than unity under the assumptions that effective rainfall is 20mm/h and continues 20 hours.

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Estimation of Superelevation in Mountainous River Bends (산지하천 만곡부의 편수위 산정)

  • Park, Sang Doeg;Lee, Seung Kyu;Shin, Seung Sook;Cho, Jaewoong
    • Journal of Korea Water Resources Association
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    • v.47 no.12
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    • pp.1165-1176
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    • 2014
  • In a river bend the water surface is inclined by the centrifugal force toward the transverse section. If channel slope and flow rate increase, the gradient is rising generally. There are lots of the flood damage at the bends of mountain river because the flood water levels have exceeded frequently the levee levels which are added a free board to the design flood water level. Therefore the superelevation should be considered in designing the mountainous river bend. In present study it was proposed to estimate the superelevation at the bend of mountain river and the superelevation coefficient defined from multiplying the sub-factors. The values of the influence factors for the superelevation coefficient were suggested from analyzing the superelevation measured at the bends in Yangyangnamdae river and the hydraulic experiments in gravel-bed channel with a 90 bend. The applicability of these methods to estimate the superelevation at the bends in mountain river was verified by the superelevation measured at the bend in Naerin river.

The appropriate shape of the boundary transition section for a mountain-gorge terrain model in a wind tunnel test

  • Hu, Peng;Li, Yongle;Huang, Guoqing;Kang, Rui;Liao, Haili
    • Wind and Structures
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    • v.20 no.1
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    • pp.15-36
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    • 2015
  • Characterization of wind flows over a complex terrain, especially mountain-gorge terrain (referred to as the very complex terrain with rolling mountains and deep narrow gorges), is an important issue for design and operation of long-span bridges constructed in this area. In both wind tunnel testing and numerical simulation, a transition section is often used to connect the wind tunnel floor or computational domain bottom and the boundary top of the terrain model in order to generate a smooth flow transition over the edge of the terrain model. Although the transition section plays an important role in simulation of wind field over complex terrain, an appropriate shape needs investigation. In this study, two principles for selecting an appropriate shape of boundary transition section were proposed, and a theoretical curve serving for the mountain-gorge terrain model was derived based on potential flow theory around a circular cylinder. Then a two-dimensional (2-D) simulation was used to compare the flow transition performance between the proposed curved transition section and the traditional ramp transition section in a wind tunnel. Furthermore, the wind velocity field induced by the curved transition section with an equivalent slope of 30 was investigated in detail, and a parameter called the 'velocity stability factor' was defined; an analytical model for predicting the velocity stability factor was also proposed. The results show that the proposed curved transition section has a better flow transition performance compared with the traditional ramp transition section. The proposed analytical model can also adequately predict the velocity stability factor of the wind field.

Study on Applicability of Slope Types to Permission Standard for Forestland Use Conversion (산지의 사면유형을 고려한 산지전용허가기준에 관한 연구)

  • CHOI, Jung-Sun;KWAK, Doo-Ahn;KWON, Soon-Duck;BAEK, Seung-A
    • Journal of the Korean Association of Geographic Information Studies
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    • v.21 no.4
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    • pp.145-157
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    • 2018
  • Mountainous areas are 64% in Korea and are allowed to be used by the permission standards of the "Mountainous Districts Management Act". In the act, slope and elevation criteria are defined to regulate the use of vulnerable land parcels to disaster. However, the standards cannot represent topographical variation in a land parcel such as terrain relief. Therefore, the applicability of slope type standard as a permission standard was tested using Catena in this study. Based on the theoretical grounds, two slope types were analyzed as 'risky slope' with disaster risk. The slope types of landslides in Namwon City were analyzed that 'risky slope' types were distributed about 57%. This study analyzed the forestland parcels that could be used when applying the current permission standards and the parcels that were already used in Namwon City. The ratio of the 'risky slope' in the parcels was more than 50%. Therefore, it is necessary to prevent the mountain development in 'risky slope' by establishing permission standard related to slope types. In addition, this study suggested the ratio of 'risky slope' in the parcel for the permission standard for forestland use conversion.

Evaluation on Risk Assessment for Landslide Hazard of Soil Slope Using the Checklists as a Preliminary Investigation Method (점검표를 이용한 토질사면 산사태 예비조사 방법 평가)

  • Kim, Jae Min;Choi, Jung Chan
    • Economic and Environmental Geology
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    • v.48 no.2
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    • pp.177-185
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    • 2015
  • The objective of this study is to evaluate landslide hazard susceptibility and produce the landslide hazard maps for soil slope using checklists as a preliminary investigation method. Tables, proposed by NDMI (National Disaster Management Institute), are applied for slope stability assessment, and are comprised of checklists on soil slopes. Database including engineering properties of soil is constructed through the field survey and results from previous studies for The Mt. Hwangryoeng area at center of Busan. All data related to creating the thematic maps was carried out using ArcGIS 10.0. Results from using this method indicated that soil slope are evaluated from very stable to stable. Moderate stability has been partially presented along the edge of mountain. Results from landslide hazard maps can be used to prevent damage from landslides and facilitate appropriate land use planning.

Reduction Rate of the Total Runoff Volume though Installing a Rainfall Storage Tank in the Sub-Surface (지하 빗물저류시설의 설치에 따른 유출 저감 효과 분석)

  • Choi, Gye-Woon;Choi, Jong-Young;Li, Jin-Won
    • Journal of Korea Water Resources Association
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    • v.36 no.3 s.134
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    • pp.455-464
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    • 2003
  • In this paper, the experiments with installing a rainfall storage tank in the sub-surface were conducted and the reduction rates of the total runoff volume were investigated. The analysis were conducted based upon the variations of the rainfall intensity, surface coverage and surface slope. The reduction rate of the runoff volume was varied from 42.3% to 52.9% with the soil in the bank of the Seung Gi stream. In the experiments, the rainfall intensities were varied from 40mm/hr to 100mm/hr and the results indicate that the direct runoff reduction can be obtained with the installation of the rainfall storage tank in the sub-surface. The variation of the stored volume in the tank is very large in the mild slope but very small in the steep slope with over 3% slope. With this results, the reduction of the direct runoff volume for the longtime flood is expected with the installation of the rainfall storage tank in the region haying the steep slope such as the mountain area.

Susceptibility Analysis for Rock Slope Hazard Using the Empirical Method (경험론적 방법을 이용한 암반사면재해 취약성 분석)

  • Kim, Jae Min;Choi, Jung Chan
    • The Journal of Engineering Geology
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    • v.24 no.4
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    • pp.473-486
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    • 2014
  • The objective of this study is to produce the rock slope hazard map on the Mt. Hwangryeong located at center of Busan Metropolitan City for evaluating the rock slope hazard susceptibility. The Mt. Hwangryoeng is located between Dongrae and Ilkwang faults and consists of various rocks such as sedimentary rock, andesitic volcanic rock, andesite, gabbro and granitic rocks. Thematic maps were carried out using ArcGIS for Database including the orientations and density of joints, strength of rock constructed through the field survey and results from previous studies. Also, rock slope hazard susceptibility for the Mt. Hwangryoeng area was studied using empirical method through checklists proposed by NDMI (National Disaster Management Institute). Results from using the empirical method indicated that rock slopes are evaluated from very stable to stable, but moderate stability has been partially presented along the edge of the mountain area.

A Study on Seismic Retrofit Design of the Stabilized Piles by 1g Shaking Table Tests and Pseudo-static Analysis (1g 진동대 실험 및 등가정적해석을 이용한 억지말뚝의 사면안정 내진보강 효과 연구)

  • Han, Jin-Tae;Cho, Jong-Suck;Yoo, Min-Taek;Lee, Seung-Hyun
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.2
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    • pp.93-101
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    • 2011
  • Korea has about 70% of its land classified as the mountain area, which has led to cut-slope being the result of substantial road and railway construction. However, there is currently a lack of research about the seismic retrofit design of a slope, even though many earthquakes have recently occurred at home and abroad. In this study, in order to investigate the stabilizing effect of piles against sliding during an earthquake, a series of 1 g shaking table tests and pseudo-static analyses were carried out. As a result, the stabilizing effect of piles against sliding during an earthquake was verified by the 1 g shaking table tests and the most effective result from the pseudo-static analyses was that the installation of the piles on the central part of the slope, where the failure surface included piles unlike the lower part and upper part of the slope. Furthermore, when the pile was installed on the central part of the slope, the change of the safety factor depending on the distance between the center of two piles was evaluated.

Characterization of the Distribution of Indicator Species Beetles in the Mt. Mangunsan Area

  • Junsu Kim;Man-Leung Ha;Hyun Kim;Chong Kyu Lee
    • Journal of Forest and Environmental Science
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    • v.40 no.2
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    • pp.82-89
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    • 2024
  • This study aimed to investigate habitat distribution and beetle diversity, using beetles as biological indicator species to assess environmental changes in the Mt. Mangunsan area near the South Sea of Korea. Plots were installed at varying elevations on the southern and northern slopes of Mt. Mangunsan, and the beetle species composition was determined. A total of 1,368 beetles comprising 32 species belonging to ten families were collected between May and September 2023 from the study sites in the Mt. Mangunsan area near the South Sea of Korea. The two most prevalent species consisted of Synuchus nitidus, with 152 collected beetles, and Calosoma chinense, with 128 collected beetles. In May, June, July, August, and September, 76 beetles comprising 10 species, 180 beetles comprising 18 species, 138 beetles comprising 15 species, 525 beetles comprising 27 species, and 449 beetles comprising 25 species were collected, respectively, with the highest abundance observed in August. In terms of elevation, 239 beetles comprising 19 species were collected at 300 m; 352 beetles comprising 27 species at 400 m; 314 beetles comprising 24 species at 500 m; 280 beetles comprising 22 species at 600 m; 183 beetles comprising 16 species at 700 m. Based on the slope, 442 beetles comprising 18 species belonging to eight families were collected on the southern slope, and 926 beetles comprising 24 species belonging to 10 families were collected on the northern slope. Analysis of the beetles on the southern slope produced the following estimations: diversity of 1.086, evenness of 0.866, and dominance of 0.109. Meanwhile, those in the northern slope yielded a diversity of 1.204, evenness of 0.873, and dominance of 0.081.