• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.297-297
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• 2023

최근 친수성, 경관, 생태계 보전 등을 위해 다양한 호안블록의 시공이 이루어지고 있어 호안블록의 수리적 안정성에 관한 관심이 증가하고 있다. 이러한 배경 하에 한국건설기술연구원 안동하천실험센터(이하 센터)에서는 2019년부터 실규모 수로를 이용하여 여러 건의 호안블록 실규모 수리검토 실험을 실시한 바 있다. 본 연구는 그간의 실험 결과를 종합적으로 고찰하고 수리 검토 실험의 현황과 한계점, 그리고 개선 방향을 제언하는데 그 목적이 있다. A1 수로(급경사수로, 하상경사 1/70)에서는 7건(21회), B1 수로(고유속수로, 하상경사 1/7)에서는 2건(6회)의 실험이 수행되었다. A1 수로 실험의 유량-소류력 관계는 1.0 m³/s에서 약 20 N/m²이며, 1.0 m³/s 증가당 약 11 N/m²이 증가하는 관계를 나타낸다. 7건의 실험 결과 30분 이상 지속된 최대 실험 유량은 6~7 m³/s 정도이며, 이는 A1 최대 공급 유량의 75 % 정도로서 안정적인 수준이라고 판단된다. 이 때의 최대 소류력은 75 N/m² 정도로 나타났다. B1 수로는 5 m/s 이상의 고유속 흐름을 발생시킬 수있으며, 2건의 실험 결과 0.5 m³/s에서 약 100 N/m², 최대 4.5 m³/s에서 330 N/m²까지 소류력을 제공하여 실험을 수행한 바 있다. 따라서 A1, B1 수로를 통해 제공할 수 있는 소류력 범위는 10~330 N/m²이지만, 75~100 N/m²는 실험에서 제공된 바 없었다. 한편, 토양유실의 경우 수준측량에 의해 측정되는데, 대부분의 실험에서 Clopper의 토양손실 지수(1.27 cm) 미만의 결과가 발생하였다. 이는 시험체에 따라 여건이 다르기는 하지만, 수리 검토 실험시 3회 실험을 기본으로 하고 있고 호안재료의 침식이 기준 이하로 유지되면서 최대한의 성능을 발휘할 수 있는 소류력 조건을 얻으려는 실험 목적에 부합하도록 조절된 것으로 볼 수 있다. 이러한 실험 결과를 토대로 고려해볼 수 있는 개선 방향은 다음과 같다. 강성 재료가 아닌 연성 또는 친환경적 호안재료의 허용 소류력 범위를 보다 넓게 평가하기 위해 A1 수로가 제공하는 최대 소류력을 높일 필요가 있다. 이를 위해 기본 3회의 실험 외에 추가로 호안블록이 파괴되거나 토양유실 임계치를 초과할 수 있는 실험을 수행함으로써 각 제품의 한계 성능을 평가하는 것이 필요할 것으로 보인다.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.534-544
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• 2009

The collapse of the underground cavity can cause the abrupt local subsidence of the ground surface. It can be hazardous to the stability of road and building for human activity. Therefore it is necessary to develop reinforcement methods for the filling of the underground cavity. This study was executed to improve the material quality and systems to fill the calcium-aluminate mineral $(C_{12}A_7)$ environmentally, and minimize the loss of filling materials for the steep underground cavity. Filling material which was developed in this study is composed of rapid hardening material and additives. The developed material had rapid hardening and non-separation ability in the water cavity condition, so it made the effective underground dam in the cavity with prevention of material loss when it was poured in the water cavity. Results of heavy metal leaching test for environmental assessment showed that it was environmentally suiTable material for the filling in the mine cavity.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.1
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• pp.28-34
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• 2010

The spatial distribution characteristics of damaged trees by the pine wilt disease appear scattered spots spreading from single dead trees. That is the reason why it is difficult to early detect damage and to prevent from extensive damage. Thus, it is very important to forecast and analyze the damage occurrences, to establish strategies for prevention, and to supervise them. However, conventional survey which observes around roads or residential areas by naked eyes was impossible to investigate completely, missing target areas and dangerous areas. Therefore, aerial forecasting techniques on the damaged area were developed using GIS, GPS, and helicopters for an accurate observation of systematic and scientific approach in this study. Moreover, advantages of the techniques application were confirmed to survey 972 dead tree samples at 349 position-coordinates in 32 cities (about $28,810km^2$), 2005. This study is expected to apply widely to find dead trees and the causes, particularly by pine wilt disease.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.161-168
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• 2003

Most natural deposits of sandy soil possess some degree of cementation resulting from the deposition and precipitation of cementing agents. The presence of cementation can have a significant influence on the stiffness and volume change behavior, and the strength of soils. An important feature of deposits of cemented sandy soils is their ability to remain stable in surprisingly high and almost vertical man-made cuts as well as natural slopes. Numerous field observations and studies of failures in slopes of cemented soils have reported that application of conventional analysis techniques of slope stability is inadequate. That is not only due to the fact that the failure surface of the slope is not circular, but also the fact that the average shear stress along the failure surface is much smaller than the shear strength measured in laboratory shear experiments. This observation alerts us to the fact that a mechanism different from conventional Mohr-Coulomb shear failure takes place, which may be related to fracture processes, which in turn are governed by fracture mechanics concepts and theory. In this study, steep slopes in cemented sand were assessed using fracture mechanics concepts. The results showed that FEM coupled with fracture mechanics concepts provides an excellent alternative in the design and safety assessment of earth structures in cemented soils.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.571-582
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• 2010

Typically nondestructive inspection methods of the large gear units are applied to penetrate non-destructive inspection. Nondestructive penetrating inspection put into the small openings of the defect to penetration liquid, remove to excess penetration liquid on the surface of the gear units, spread with developing solution and we can find the small defect by coating with penetration liquid. However, this method has so many issues because of penetrate nondestructive tests on the gear assembly. The steep angle of screw is hard to achieved full penetration and has the problem to remove the excess. In contrast, the magnetic nondestructive inspection is easy to detect subsurface defects and subtle defects. According to the inspection results the stress concentrates in gear surface, some internal defects and microscopic flaws exist on the gear units are not found to penetrate the nondestructive inspection, but magnetic nondestructive inspection could have found many defect. Therefore, a reasonable method of nondestructive inspection for the large gear units is suitable to magnetic nondestructive inspection.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.169-177
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• 2000

The modelling technique on the terrain of real-world in geo-spatial information system is a primary element for geo-information processing. This paper is designed to make use of TIN in geo-spatial information system and study the development and application of high-precision 3-D spatial analysis technique applied to terrain features. According to this research, MODEL 3 applied to breakline in mild slope/steep slope and MODEL 2 applied to peak in complex region show relatively low RMSE. This consequence proves that these two models have high precision in comparison with other models. This study also finds out optimal routines in the estimation method of slope grade and in the construction method of surface. N_T, LSP_T and LSQ_T in mild slope, N_T in steep slope, and LSQ_T in complex region turn out to be the optimal routines for high-precision 3-D spatial analysis.

• The KIPS Transactions:PartD
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• v.16D no.2
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• pp.249-256
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• 2009

This paper introduces an efficient USN (ubiquitous sensor network) for monitoring blind areas in a skiing resort, developed as a part of u-Sport showcase project of Gangwon Province. Blind areas of a skiing resort are dangerous and/or steep areas located aroud ski slopes, which are rarely traveled and not easily seen by a ski patrol. If an accident occurs in such a blind area, the main control center of the sking resort can hardly recognize the accident and provide first aid and rescue services promptly. The blind area monitoring system proposed in this paper monitors a blind area of a skiing resort using five battery-powered sensor nodes each of which has an image sensor on it and wirelessly transmits images around the blind area to the main control center on a regular basis, therebly allowing real-time monitoring of the blind area and prompt rescue services in case of accidents. Additionally, the monitoring system provides an emergency button which skiers injured in the blind area can push. If the button is pushed, an image around the button and an alarm signal are transmitted to the main control center and therefore the main control center can take prompt actions for rescuing the injured skiers.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1033-1039
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• 2018

In Korea, every year during the summer season, typhoons and torrential rains cause floods and damage to property. In particular, the Imjin River basin is characterized by steep slopes, narrow upstream areas, and low flat downstream areas, which are vulnerable to floods. In addition, damages occurred due to unauthorized discharge in the Hwanggang Dam, a large dam upstream of the Imjin River in North Korea. In order to prevent such flood damage, Korea is constructing the Gunnam Flood Control Site in 2010 to prevent flood damage. However, even after the construction of the flood control zone, the flood control capacity is only 20% of the maximum water level of the Hwanggang dam. This study used LAHARZ_py program to calculate flood damage area in the northern part of Gyeonggi province. As a result, when the discharge of Hwanggang dam exceeding the flood control ability of Gunnam flood control zone occurs, damage to Yeoncheon-gun and Paju-si of Gyeonggi-do was expected. This study will be useful as a material to prepare for flood damage.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.541-547
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• 2021

To assess the stability of a slope and the likelihood of its loss or collapse requires information about the ground, such as the composition of the stratum and its mechanical characteristics. This information is generally gathered through standard penetration testing (SPT) and cone penetration testing. SPT is not widely used due to problems with accessing slopes, most of which are steep and without ramps. A drop cone penetrometer, a portable device that can make up for these shortcomings, can be used in a limited way in some circumstances. Therefore, we developed a portable drilling machine and a small dynamic cone penetration test module that can easily access a slope site and perform SPT. The correlation of the developed system's results with those from SPT was analyzed. Analysis of the correlation between the energy shear rate passing to the load during the different test types established that the energy shear rate is reflected in the test result. The correlation between corrected dynamic cone penetration testing and corrected SPT was N_d' = 3.13 N'.

• The Journal of Engineering Geology
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• v.34 no.1
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• pp.13-24
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• 2024

The purpose of this study is to identify the geology, geologic structure, hydrogeology and geomorphic characteristics of the Nari Basin and establish the controls on the discharge of water 20,000~40,000 m³/day from the Choosan Yongchulso, Ulleung Island, South Korea. Pumice and lapilli tuffs showing well-developed stratification are the predominant rock types surrounding the spring. The spring shows a structure whereby discharge occurs along a lens-like erosion cave formed by differential erosion of strata comprising tuff or pumice tuff. The Choosan Yongchulso is located at the point where the planation surface of the Nari Basin' ends and steep slopes begin. The basin is bounded on all sides by these steep slopes, except in the north, where the Choosan Yongchulso is located. Given these geomorphic characteristics, the Choosan Yongchulso is regarded as the ultimate outlet of the basin catchment area.