• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2017.11a
• /
• pp.319-322
• /
• 2017

전 세계적으로 기후변화는 계속 진행되고 있으며, 극심한 기상변화로 인한 재난이 곳곳에서 발생하면서 기후변화에 대한 우려가 심화되는 동시에 이에 대한 연구의 필요성 역시 커졌다. 기후변화의 심각성에 대한 객관적인 자료와 연구결과는 매번 전 세계인의 이목을 받고 있다. 과거, 기후변화로 인한 재앙에 대한 우려가 생태계 파괴, 일부 동물들의 멸종과 같은 환경 문제에 그친 반면, 최근에는 전 세계 주요 도시에서 주기적으로 발생하는 대형 자연 재난이 기후변화로 인한 결과임을 인식하게 되었으며 기후변화로 인한 재난이 우리 생활권 내에 진입하면서 기후변화 문제가 생존과 안전 문제로 재인식 되었다. 우리나라 역시 매년 주기적으로 겪었던 풍수해 재난이 점차 대형화되는 것은 물론 기후변화로 인해 폭염과 가뭄이 빈번하게 발생하게 되어 경제적, 인명 피해가 꾸준히 발생하고 있다. 이에 2008년 이후 기후변화와 그로인해 발생하는 재난을 효과적으로 관리할 수 있는 체계 및 정책에 대한 필요성이 대두되면서 관련 체계와 법, 정책 수립이 적극적으로 이루어졌다. 본 논문에서는 기후변화로 인해 주기적으로 겪고 있는 국내 재난에 대해 파악하고 기후변화 적응 정책과 연구의 현황, 한계에 대해 연구하였다. 국내 재난 유형이 지역별로 다소 차이가 있음을 전제하여 재난 유형 파악 지역을 서울로 한정하였으며, 기타 시 도별 연구는 향후 연구과제로 제안하고 있다. 우선 기후변화로 인해 발생하는 서울 도심 내 재난 양상을 살펴보고 그 양상과 기후변화와의 연관성을 밝히기 위해 노력하였다.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.6
• /
• pp.151-160
• /
• 2003

The stability of the designed rock slope is analysed based on two kinds of shear strength model. Besides the deterministic analysis, a probabilistic approach on Monte Carlo simulation is proposed to deal with the uncertain characteristics of the discontinuity and the results obtained from two models are compared to each other. To carry out the research of characteristics of the discontinuity, BIPS, DOM Scanline survey data and direct shear test data are used, and chi-square test is used for determining the probability distribution function. The rock slope is evaluated to be stable in the deterministic analysis, but in the probabilistic analysis, the probability of failure is more than 5%, so, it is considered that the rock slope is unstable. In the shear strength models, the probability of the failure based on the Mohr-Coulomb model(linear model) is higher than that of the Barton model. It is supported by the fact that the Mohr-Coulomb model is more sensitive to block size than the Barton model. In fact, there is no reliable way to estimate the unit cohesion of the Mohr-Coulomb model except f3r back analysis and in the case of small block failure in the slope, Mohr-Coulomb model may excessively evaluate the factor of the safety. So, the Barton model of which parameters are easily acquired using the geological survey is more reasonable for the stability of the studied slope. Also, the selection of the proper shear strength model is an important factor for slope failure analysis.

• Journal of Wetlands Research
• /
• v.21 no.4
• /
• pp.298-304
• /
• 2019

In this paper, the analytical method to derive wind fragility for urban street tree in Korea was shown. Monte Carlo Simulation method was used to determine the probability of failure for urban street tree. This probability result was used to determine wind fragility parameters for four types of tree based on the study of street tree species in urban area in Daegu, Korea. Wind fragility for street tree was presented in terms of median capacity and standard deviation of the natural logarithm of the capacity. Results showed that the dominant factor affecting the probability of failure of tree under wind load was their diameter. Moreover, amongst the four types of tree chosen, the tree with height 7m and diameter 35cm had the lowest probability of failure under wind loading, whereas the tree with height 8m and diameter 30cm could resist the least wind loading. The median failure wind speed for urban street tree with height 7m were 43.8m/s and 50.6m/s for diameter 30cm and 35cm, respectively. Also, for tree with height 8m, their median failure wind speeds were 38.7m/s and 45.4m/s for tree with diameter 30cm and 35cm, respectively.

• Korean Journal of Heritage: History & Science
• /
• v.53 no.4
• /
• pp.78-99
• /
• 2020

The Buddha triad and 16 Arhat statues carved on the rock surface at Seongbulsa temple is the only domestic remaining example of all 16 Arhats, so its academic value is very high. However, it is severely damaged and so required a stability evaluation through study of digital documentation and precise diagnosis for the purpose of comprehensive conservation. This process established that the Buddha statues were of similar scale, while the Arhats showed a wide variety of sizes, and the two kith and kin in the volume were larger than the Arhats. It was estimated that the statues of food for Buddha are similar to the Arhat statues, and most of the statues are well-formed. The rock used to carve the Buddha statues is banded gneiss with distinct foliation, alternating between white bands of quartz and feldspar and black bands composed of biotite. The Buddha statues have been damaged by physical weathering, discoloration, and biological contamination. In damage evaluations, joint (3.6 crack index), peeling (5.2%), exfoliation (1.7%), and falling off (0.1%) were observed on the rock surface of the Buddha statues. In particular, due to severe biological weathering, stage 9 and 10 biological coverage of the rock surface accounted for 57.5% of the total area, and stages 5 to 8 also accounted for a high share at 22.3%. The discoloration factors were shown to be dark brown and white with Fe, Ca, and S, and a large amount of C detected in the blackened contaminants, and the damage weight high in all areas. Discontinuities in different directions were identified in the rock surface. Analysis of potential rock failure types indicated that there is a possibility of plane and toppling failure, but wedge failure is unlikely to occur. The mean ultrasonic velocity of the main rock surface was 2,463m/sec, the lower part of the left side with a large number of joints was relatively low, and the highly weathered (HW) type to the completely weathered (CW) type concentrated distribution, showing weak properties. For the Buddha statues, conservation treatment is required for about 14.9% of micro cracks and 58.9% of exfoliation cracks. In addition, in order to improve the conservation environment of the Buddha statues, maintenance of drainage and ground preparations for the rock surface gradient and plants are necessary, and protection facilities should be reviewed for long-term conservation and management purposes.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.6
• /
• pp.137-146
• /
• 2005

299 railroad slopes were investigated and the failure characteristics and reinforcement patterns were analyzed. Stability analyses on the 14 cut-off soil slopes were carried out. Surficial failures were predicted by infinite slope analyses assuming the temporarily perched ground water table at soil surface during rainfall period. Limit equilibrium analyses were also carried out and the influences of rainfall infiltration on the slope stabilities were taken Into account by seepage analyses using finite element method and by assuming ground water tables to be located adjacent to soil surface. The adequacy of those analyses was evaluated by comparing the slope failure characteristics between analysis results and the past failure records. From the comparison results, it was deduced that the limit equilibrium analyses were not appropriate to estimate the shallow failure that occurred at most of the railroad cut-off soil slopes. For the better estimation of the surficial failure, not only the increase of pore-water pressure (reduction of matric suction), but also the influence of water flows over slope surface which erode soil mass, should be evaluated and considered.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.11
• /
• pp.111-120
• /
• 2008

The characteristic of induced anisotropy is investigated in this study for the Pohang mudstone involving the cut plane discontinuity. The uniaxial and triaxial compression tests are performed for anisotropic rocks with artificial joint to look into anisotropic strength characteristics. Both the uniaxial compressive strength and triaxial compressive strength show the lowest value at the angle of cut plane, ${\beta}=30^{\circ}$ and the shoulder type of anisotropy is obtained. Anisotropy ratio (Rc) in uniaxial compression measures 9.0, whereas Rc=1.29-1.98 in triaxial compression is appeared. A series of analyses are made with the test results to derive the suitable parameter values when it is applied to the Ramamurthy (1985) failure criterion. The result of uniaxial compression test is analyzed by introducing the n-index into Ramamurthy failure criterion. The result shows that, n=l is suitable for ${\beta}=0^{\circ}{\sim}30^{\circ}$ and n=3 is suitable for ${\beta}=30^{\circ}{\sim}90^{\circ}$. To analyze the result of triaxial compression test by Ramamurthy failure criterion, anisotropy ratio in uniaxial compression test is added to Ramamurthy's equation and material constants are estimated by modified Ramamurthy's equation. When these values are applied back to Ramamurthy failure criterion, the predicted values are well fitted to the test results. And strength anisotropy for failure criteria of Jaeger (1960), McLamore & Gray (1967) and Hoek & Brown (1980) are also investigated.

• Journal of the Korean Geotechnical Society
• /
• v.40 no.2
• /
• pp.95-103
• /
• 2024

The global increase in population and subsequent scarcity of terrestrial living spaces necessitates exploration of alternative habitats. Research into the development of underwater living areas provides promising avenues for the expansion of human living spaces and the use of marine environments. This study focuses on the failure envelope of suction caisson foundations subjected to combined loads in a marine setting, utilizing finite element analysis. The foundation is assumed to be embedded in clay characterized by a linear increase in undrained shear strength with depth, employing the von Mises constitutive model for the clay. The resulting failure envelope is represented as a tilted ellipse which expands as the undrained shear strength increases, maintaining a constant ratio between the major and minor axes. A comparative analysis of two suction caisson foundations with varying length-to-diameter ratios revealed that this ratio influences the dimensions of the failure envelope, with a tendency for the major-to-minor axis ratio to increase as the length-to-diameter ratio increases. These findings are critical for the design of suction caisson foundations in offshore environments.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.18 no.4
• /
• pp.51-58
• /
• 2010

Recently, aerospace structures have lightweight trend in order to reduce the cost of fuel and system, Carbon Fiber Reinforced Plastic (CFRP) can give the ability to reduce weight at 20~50% as the substitution of metal alloy, and there are advantages such as high Non-rigid, specific strength and anti-corrosion, but it is difficult to prove its destruction properties due to heterogeneous structure and anisotropy. In this study we designed specimen, inducing distinguishing destructions of material (for example, matrix crack, fiber breakage, and delamination) by using the Carbon Fiber Reinforced Plastic (CFRP) which is used in a real aircraft, to apply acoustic emission technique to aerospace structures. And we gained data via tensile testing and acoustic emission technique, from which each fault signal was classified respectively by using AE parameters and waveform.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.6
• /
• pp.115-125
• /
• 2003

This paper presents the results of design case study on soil-reinforced segmental retaining walls in tiered configuration. Six different field walls were examined to investigate the appropriateness of their designs within the context of the current design guidelines based on limit equilibrium. Slope stability analysis against the compound failure mode, which is frequently ignored during design, was additionally performed based on the method recommended by FHWA design guidelines. The results indicate that the as-built designs of some of the walls examined do not meet the minimum factors of safety for the external and Internal stabilities, and for the compound failure mode. The implications of the findings from this study are discussed.

• Journal of the Korean Geographical Society
• /
• v.38 no.4
• /
• pp.610-629
• /
• 2003

Ecotourism has been considered as sustainable tourism since it has been believed to preserve the environment of a tourist destination as well as to satisfy the various needs of tourists. However, most of destinations recently developed for ecotourism have confronted environmental degradation. Therefore, it is necessary to challenge and reestablish the concept of ecotourism. This study seeks to provide new perspectives on the concept of ecotourism by estimating the sustainability of three ecotourism destinations in Jeju Island. The Yae-Rae Dong Ecotourism Village shows a high level of sustainability, while the Ah-Bu Oh-rum at Song-Dang Ri and the Experience Beach at Jong-Dal Ri shows a low level of sustainability. In result, the ecotourism in itself is not sustainable tourism, and further this study suggests that appropriate planning, development, and management of a destination are important factors to decide the success of sustainable tourism.