• The Journal of Engineering Geology
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• v.26 no.1
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• pp.129-142
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• 2016

National parks, which are located mainly in mountainous areas, are always at risk of damage by landslides. The goal of this study is to establish a method for systematically maintaining hazardous steep slopes along trails in national parks. We produced a checklist suitable for each of the 19 national parks nationwide and investigated 183 slopes. The aim of these investigations is to recommend appropriate slope-stability countermeasures, including field investigations and stability analysis. We made preliminary investigations at specific sites, evaluating the slope hazard using specialized equipment such as terrestrial LiDAR. An investment priority formula was developed, and ranking and hazardous grades were calculated as part of a long-term maintenance plan. Finally, to systematically manage dangerous slopes and to house all the field data within one system, we developed the "Slope Maintenance System in National Parks" based on web server that can show various information for slopes.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.83-94
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• 2012

Slopes are commonly formed both above and below roads located in mountainous terrain and along riversides. The Buk-sil site, a cut slope formed below the road, collapsed in October, 2010. A field investigation determined the causes of failure as improper drainage of valley water from the slope above the road and direct seepage of road-surface water. These factors may have accelerated the collapse via complex interaction between water and sub-surface structures such as bedding. Projection analysis of the site showed the possible involvement of plane, wedge, and toppling failure. Safety factors calculated by Limit Equilibrium Analysis for plane and wedge failure were below the standard for wet conditions. The wetness index, analyzed using topographic factors of the study area, was 9.0-10.5, which is high compared with the values calculated for nearby areas. This finding indicates a high concentration of water flow. We consider that water-flow control on the upper road is crucial for enhancing slope stability at the Buk-sil site.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.599-604
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• 2005

최근 일부 댐유역에서 게릴라성 집중호우와 태풍 등과 같은 특이 호우에 대하여 강우-유출분석을 실시한 결과 유출율이 $100\%$를 상회하는 경우가 발생함에 따라 효율적이고 안전한 치수 및 방재업무를 실시하는데 많은 어려움을 겪고 있다. 본 연구에서 일부 댐유역의 유출율이 $100\%$를 상회하는 원인으로 강우 관측자료의 신뢰성이 결여되어 나타나는 것으로 보았으며, 만일, 강우관측소에서 계측된 강우자료의 신뢰성이 결여 되어 있다면, 이로 인한 유역 강우의 추정오차는 제거될 수 없을 것이다. 일반적으로 강우관측소에서 발생하는 계측오차는 관측소의 고도, 지형적인 장애(산악영향, 지장물 등) 및 기상학적인 장애(기단의 이동방향, 호우의 발생원인, 돌풍 등) 등 외부적인 요인으로 인해 발생할 수 있다. 따라서, 본 연구에서는 강우관측소에서 발생하는 계측오차의 다른 여러 외부적 요인들 중 가장 큰 요인으로 돌풍과 같은 풍속에 의해 발생하는 것으로 판단하였고, 연구대상 유역인 임하댐 유역의 유출율과 치대 풍속간의 상관분석을 실시하였으며 분석결과 유출율은 최대 풍속에 커다란 영향을 받는 것으로 나타났다. 결국, 유출율이 $100\%$를 상회하는 호우에서 강우관측소의 강우는 강우시 돌풍과 같은 외부적인 요인으로 인해 적게 관측된 것으로 추정되며 저평가된 강우자료로부터 산정된 면적평균강우의 추정오차로 인해 유출율이 $100\%$를 상회하는 것으로 나타났다. 따라서 본 연구에서는 유출율과 풍속간의 관계로부터 강우보정계수 추정식을 산정하였으며, 추정된 보정계수를 이용하여 관측된 강우자료를 보정한 후 강우-유출분석을 실시한 결과 댐유입수문곡선을 보정전에 비해 보다 근사하게 모의하였다. 위해서는 대상유역에 적합한 선행 강우일수의 결정이 중요하리라 판단된다.인 분석을 수행하고, 배수갑문 개방에 의한 수질개선효과를 최대화하기 위한 환경관리 방안 제시에 중점을 두어 수행하였다.ncy), 환경성(environmental feasibility) 등을 정성적으로(qualitatively) 파악하여 실현가능한 대안을 선정하였다. 이렇게 선정된 대안들은 중유역별로 검토하여 효과가 있을 것으로 판단되는 대안들을 제시하는 예비타당성(Prefeasibility) 계획을 수립하였다. 이렇게 제시된 계획은 향후 과학적인 분석(세부평가방법)을 통해 대안을 평가하고 구체적인 타당성(feasibility) 계획을 수립하는데 토대가 될 것이다.{0.11R(mm)}(r^2=0.69)$로 나타났다. 이는 토양의 투수특성에 따라 강우량 증가에 비례하여 점증하는 침투수와 구분되는 현상이었다. 경사와 토양이 같은 조건에서 나지의 경우 역시 $Ro_{B10}(mm)=20.3e^{0.08R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며 $10\% 경사일 때를 기준으로 $Ro(mm)=Ro_{10}{\times}0.797{\times}e^{-0.021s(\%)}$로 나타났다.천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러나 진단 즉시 직접 좌관상동맥-대동맥 이식술로 수술적 교정을 해줌으로

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.131-143
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• 2010

This study has aimed to develop accident modification factor(AMF) for rural two-lane roadway segments. Accident Modification Factor is a coefficient to assess roadway safety as reflecting characteristics of homogeneous roadway. It estimates accident frequency of roadway segments with developed base model and exposure. We found on items of such factors as crosswalk, driveway density, topography characteristic, land use and median through statistical models and literature review. To develop accident modification factors, we used statistical model methods and analyses of applicability and expert judgement method were practiced to validate it. Although expert judgement for land use item was questionable, most items were rated acceptable. Result of comparative analysis revealed crash frequencies of IHSDM and KHSEM were most similar with actual. However, accident distribution of KHSEM was more proper than IHSDM. Also overall estimated values of RSDS were found to be overestimated.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.1-8
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• 2010

Construction of road closed to mountains is inevitable in Korea because the mountainous region in Korea is more than 70% in area. Recently, due to global warming, typhoons or heavy rainfalls frequently occur, and accordingly, mountain roads are seriously damaged by landslides, debris flows, and uplift pressure below pavement. in this study, damage on pavement by uplift pressure was investigated. Various influencing factors such as slope angle, reinforcement of slope surface, thickness of soil cover underlain by rock, and types of drainage system were considered to evaluate uplift pressure acting on the bottom of pavement. Raising of water table up to the surface of slope may depend on the duration and intensity of rainfall. It shows that the installation of subdrain can reduce the uplift water pressure. Therefore, It is concluded that the use of subdrain system is effective to decrease uplift pressure and cement treated base is more endurable than typical crushed-stone base.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.293-301
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• 2005

In case of the roads that pass the mountain area, the cut sections or the tunnels are constructed. And In winter season it appears sunshine few in the specific segment, the shade is continued last and the freezing sections occur. So, the attention is necessary in traffic safety. This study was to evaluate the influence of sunshine and surface freezing sections expected in route plans of roads using GIS and makes alternative ideas in road stability security. After selecting 29 km sections of Donghae highway and creating a 3 dimensional terrain surface through the digital conversion of design plan data, it reflects the road alignment data of the same coordinates and a 3 dimensional road modeling is created. It set shadow time of road surface for the solar trace in the winter solstice in 20 minute interval. Shade areas are displayed and inputed in polygon data by manual vertorizing. Graphic and attribute data of this shade section is constructed in geodatabase of ArcCatalog. And it extracted the freezing section using intersect fuction of the GIS spatial analysis. By analyzing the winter meteorological data of temperature, rainfall, snowfall, humidity, and etc. and grasping dangerous freezing section of the road surface effectively, it will be able to make alternative ideas of the preliminary stability evaluation reflected in basic design.

• Journal of Aerospace System Engineering
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• v.14 no.1
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• pp.68-73
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• 2020

This purpose of this paper was to review the development trend of the VTOL MAVs with a ducted propellant that can fly like the VTOL at intermediate and high speeds, hovering, landing, and lifting off vertically over urban areas, warships, bridges, and mountainous terrains. The MAV differs in flight characteristics from helicopters and fixed wings in many respects. In addition to enhancing thrust, the duct protects personnel from accidental contact with the spinning rotor. The purpose of the U.S. Army FCS and DARPA's OAV program is spurring development of a the VTOL ducted MAV. Today's MAVs are equipped with video/infrared cameras to hover-and-stare at enemies hidden behind forests and hills for approximately one hour surveillance and reconnaissance. Class-I is a VTOL ducted MAV developed in size and weight that individual soldiers can store in their backpacks. Class-II is the development of an organic VTOL ducted fan MAV with twice the operating time and a wider range of flight than Class-I. MAVs will need to develop to perch-and-stare technology for lengthy operation on the current hover-and-stare. The near future OAV's concept is to expand its mission capability and efficiency with a joint operation that automatically lifts-off, lands, refuels, and recharges on the vehicle's landing pad while the manned-unmanned ground vehicle is in operation. A ducted MAV needs the development of highly accurate relative position technology using low cost and small GPS for automatic lift-off and landing on the landing pad. There is also a need to develop a common command and control architecture that enables the cooperative operation of organisms between a VTOL ducted MAV and a manned-unmanned ground vehicle.

• Journal of the Korean earth science society
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• v.36 no.6
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• pp.553-566
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• 2015

The effects of vertical resolutions and planetary boundary layer (PBL) physics schemes in a numerical simulation with a very high resolution over the metropolitan area were investigated. The numerical experiments using the Weather Research and Forecast model were conducted from 0000 UTC 25 October to 0000 UTC 26 October 2013. We verified the numerical results against with six hourly observation data from the radiosonde at Seolleung, which was located in southern part of Seoul, and forty three auto weather systems in Seoul. In the experiments of vertical resolutions in low level atmosphere with 44, 50, and 60 layers, which are set to be subdivided particularly under 2 km height. The experiment in 60 layers, which has the highest vertical resolution in this study, showed relatively a clear diurnal variation of PBL heights. Especially, the difference of PBL heights and 10-meter wind fields were mainly seen in the area of high altitude lands for the experiments of vertical resolution. In the sensitivity experiment of PBL schemes such as asymmetric convective model-version 2 (ACM2), Yonsei University (YSU), and Mellow-Yamada-Janjic (MYJ) to the temperature, all three PBL schemes revealed lower temperature than observed profile from the radiosonde in the entire period. The experiments with YSU PBL and ACM2 PBL schemes show relatively less biased in comparison with the experiment of the MYJ PBL scheme.

• Journal of the Korean Geophysical Society
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• v.9 no.1
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• pp.47-62
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• 2006

More than 70% of Korean Peninsula is consisted of mountains, so that lots of roads, rail-roads and tunnel,which play a pivotal role in the industry activity, are existed along the rock-slope and in the rock-mass. Thus,it is urgent that tegration of management system through the optimum survey and design of rock-slope excavation, proper stabilization method and database of rock-slope. However, conventional methods have shortcoming with the economy of survey time and human resources, and the overcome of difficulties of approach to the in-situ rock-slope. To overcome the limitation of conventional method, this paper proposed the development of remote measurement system using Terrestrial Laser Scanning System. The method using Terrestrial 3D Laser Scanning System, which can get 3D spatial information on the rock-slope and2)Dept. Geosystem Engineering, Kangwon National University, Korea tunnel, has an advantage of reduction of measurement time and the overcome of difficulties of approach to the in-situ rock-slope/dam/tunnel. In the case of rock-slope, through the analysis of 3D modeling of point-cloud by Terrestrial Laser Scanning System, orientation of discontinuity, roughness of joint surface, failure shape and volume were successively achieved. in the case of tunnel face, through reverse-engineering, monitoring of displacement was possible.

• Journal of Korea Water Resources Association
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• v.49 no.5
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• pp.373-380
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• 2016

The NRCS-CN (Natural Resources Conservation Service-Curve Number) method has been practically applied for estimating the effective precipitation. However, there are no criteria which reflect the geographic characteristics of Korea having more than 70% of mountainous and rice paddy areas, leading to significant errors in runoff calculation. Thus, it is required to estimate the runoff curve number considered Korea land use classification, however there are practical difficulties to conduct the accurate research and experimentation. In this study, after selecting target areas (urban, agriculture, forest), we performed the runoff analysis to redetermine CN values for the selected basins. To do this, curve numbers for soil type A were estimated using genetic algorithm, and then curve numbers for soil type (B, C, D) were estimated using CN aligner equation. Comparing the initial curve numbers with the estimated curve numbers, it was observed that the slightly differences at Chunwang(0), Choonyang(-1), Janggi(-3). Through the above process, this study proposed new curve numbers to reflect observed rainfall-runoff.