• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.71-80
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• 2018

In this study, the seismic response of cut-and-cover box tunnels is evaluated from pseudo-static analyses and the fragility curves are derived. A series of site profiles were used to evaluate the effect of soil conditions. A total of 20 ground motions were used. The fragility curves were developed as functions of peak ground acceleration for three damage states, which are minor, moderate, and extensive states. The damage indices, defined as the ratio of the elastic moment to the yield moment, correlated to three damage states, were used. The curves are shown to greatly depend on the site profile. The curves are further compared to those derived in previous studies. The widely used empirically derived curves are shown not to account for the site effects, and therefore underestimate the response for soft sites.

• Structural Engineering and Mechanics
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• v.78 no.1
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• pp.53-66
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• 2021

The determination of the damage index to reveal the performance level of a structure can constitute the seismic risk generalization approach based on the parametric analysis. This study implemented this concept to one kind of civil engineering structure that is the concrete gravity dam. Different cases of the structure exhibit their individual responses, which constitute different considerations. Therefore, this approach allows the parametric study of concrete as well as soil for evaluating the seismic nature in the generalized case. To ensure that the target algorithm applicable to most of the concrete gravity dams, a very simple procedure has been considered. In order to develop a correlated algorithm (by response surface methodology; RSM) between the ground motion and the structural property, randomized sampling was adopted through a stochastic method called half-fractional central composite design. The responses in the case of fluid-foundation-dam interaction (FFDI) make it more reliable by introducing the foundation as being bounded by infinite elements. To evaluate the seismic generalization of FFDI models, incremental dynamic analysis (IDA) was carried out under the impacts of various earthquake records, which have been selected from the Pacific Earthquake Engineering Research Center data. Here, the displacement-based damage indexed fragility curves have been generated to show the variation in the seismic pattern of the dam. The responses to the sensitivity analysis of the various parameters presented here are the most effective controlling factors for the concrete gravity dam. Finally, to establish the accuracy of the proposed approach, reliable verification was adopted in this study.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.591-601
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• 2021

As the domestic chemical industry continues to develop, handling and transportation of chemicals increases every year. Road freight in Korea accounts for more than 90%, and most of the chemical transportation is done through roads. These chemical vehicles can lead to major accidents if accidents occur. Transportation vehicles are likely to cause water pollution and soil pollution, which are factors of environmental damage, as well as traffic accidents that are the primary damage. In this work, we write a scenario for hydrogen chloride gas leakage by setting Banpo IC and Seocho IC sections as research areas, and use the ALOHA program to measure the predicted distance and analyze the time when hydrogen chloride gas reached according to the distance. In addition, risk assessment using population density was carried out for areas of damage caused by time using GIS. This suggests the need for prevention and countermeasures in areas of damage.

• Journal of Korean Society of Disaster and Security
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• v.14 no.1
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• pp.51-59
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• 2021

In Korea, where 64% of the soil is mountainous, typhoons and local rains concentrated in the summer season are frequent in mountainous disasters such as landslides and debris flow. The area of study was the area where the damage to the debris flow was caused by typhoon Mitag in October 2019, and all the houses located in the downstream area were damaged. In this study, numerical simulations were conducted on the area where the damage of earth and stone flow occurred using Hyper KANAKO model that can consider erosion and sedimentation, and the applicability of the model was examined by comparing the actual damage area and the analysis results of the model. As a result of the numerical simulation, the damage area of the debris flow in the target area was 53,875 m², the maximum flow depth was 2.4 m, and the average flow depth was 1.7 m.

• Structural Engineering and Mechanics
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• v.78 no.3
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• pp.351-368
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• 2021

This paper, by applying a reliability-based framework, develops seismic vulnerability macrozonation maps for Tehran, the capital and one of the most earthquake-vulnerable city of Iran. Seismic performance assessment of 3-, 4- and 5-story steel moment resisting frames (SMRFs), designed according to ASCE/SEI 41-17 and Iranian Code of Practice for Seismic Resistant Design of Buildings (2800 Standard), is investigated in terms of overall maximum inter-story drift ratio (MIDR) and unit repair cost ratio which is hereafter known as "damage ratio". To this end, Tehran city is first meshed into a network of 66 points to numerically locate low- to mid-rise SMRFs. Active faults around Tehran are next modeled explicitly. Two different combination of faults, based on available seismological data, are then developed to explore the impact of choosing a proper seismic scenario. In addition, soil effect is exclusively addressed. After building analytical models, reliability methods in combination with structure-specific probabilistic models are applied to predict demand and damage ratio of structures in a cost-effective paradigm. Due to capability of proposed methodology incorporating both aleatory and epistemic uncertainties explicitly, this framework which is centered on the regional demand and damage ratio estimation via structure-specific characteristics can efficiently pave the way for decision makers to find the most vulnerable area in a regional scale. This technical basis can also be adapted to any other structures which the demand and/or damage ratio prediction models are developed.

• Journal of Korean Society of Forest Science
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• v.73 no.1
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• pp.63-69
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• 1986

In general, the snow injury in forestry is an unusual disaster. The degree of snow injury varies greatly depending on stand density and the local topography. This study was conducted to investigate the snow injury in analyzing the demaged by snow-fall in Jinju, Gyeongsangnamdo. The results obtained were summarized as follow; Among 466 total damaged trees, 425 trees were broken and 41 trees were uprooted, the ratio of damage were 5.22%, 2.49%, 0.92% and 0.2% for Pinus densiflora, Pinus thunbergii, Pinus rigida, Alnus hirsuta respectively. The 95% of the damage trees were in the range of 3 to 11 m for height and in the range of 3 to 20 cm for D. B. H.. The directions of the damage trees had a large influence by direction of the wind, but they shown at high tendency to aspect of the slope relatively. The 82% of the damaged trees ranged from 11 to 24 age. The ratio of broken height ($H_B/H$) indicated that the damage was most frequent in the part of stem as 24%, 45%, 31% in the part of the root collar (0.1), stem (0.2-0.4), crown (0.5-1.0) respectively. In general, trees with stem-form coefficient ($H_B/D$) over 0.7-0.8 are apt to suffer by snow damage. The average of stem-form coefficient of trees in this area was 1.06. Therefore, the ratio of damage was high tendency as 3.14%. These results indicate that it is necessary to apply pertinent tending which will increase in resistance of snow damage. As avalanches from the flank of soil erosion rise in an importance matter in present, it should also be considered to measures for prevention and restoration.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.291-296
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• 1986

A pot experiment was conducted to find out the effects of water management and application of slaked lime and wollastonite on Pb uptake of rice in a Pb added soil. The soil was adjusted to 0, 150, 300 and 600 ppm of Pb concentration. The slake lime was applied at the equivalent amount of lime requirement with 150kg/10a adding and the wollastonite, 200kg/10a, respectively. The results obtained were as follows. 1. The lead contents in leaf stem and brown rice increased with increasing the soil Pb content and the ratio of Pb/(Ca+Mg) equivalent in soil but they showed no influence on yields. 2. The application of lime and wollastonite reduced Pb content in plant. 3. The lead content in plant was higher in intermittently irrigated treatment than in submersed irrigation. 4. The soil pH was increased in the order of lime, wollastonite and control. 5. $1N-NH_4$ OAC soluble Pb content in soil was higher in the submersed irrigation than in the intermittently irrigated and was higher in wollastonite application treatment than the slaked lime after harvesting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.45-53
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• 2018

Among the various slope stabilization methods, the green soil method based on the growth of plants is advantageous to the environment, but the durability and slope stability are insufficient when the green soil method is applied to a steep slope and rock slope sites. Therefore, in this study, green soil, which improved the adhesion performance and the vegetation environment, was developed using cementitious materials and ECG, and the durability and slope stability as well as the possibility of its use as a rock vegetation base material were assessed. From the results, the adhesive force and internal friction angle were higher than that of the existing green soil so that it could be used for in situ construction. The soil hardness value was 26 mm, which was slightly higher than that of the best growth condition of the plant, 18~23 mm, and the drying shrinkage strain was approximately 3%; hence, it is not expected to affect the durability of green soil. The results of a rainfall intensity simulation for evaluating the slope adhesion force showed that slope failure did not occur under all conditions. The damage decreased with increasing slope angle. Therefore, the green soils developed in this study have excellent durability and slope stability and can be used for rock slope sites.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.352-359
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• 2015

This study was conducted to evaluate how the special protection area designations of degraded trails effect on the soil and vegetation recovery of degraded trails. The study areas were established on an opened trail and a 16-year closed trail, which was prohibited to enter after the designation as a special protection area for recovery, at Bukhansan National Park. Soil core sampling and measurements of vegetation cover were performed to compare soil and vegetation properties of the trails. Soil bulk density increased and soil water total nitrogen decreased on the opened trail, while no significant differences were found on bulk density, soil water, total nitrogen, acidity, and organic matter on the closed trail. On the opened trail, vegetation cover was seemed to be degraded, because vegetation litter cover ratio was low and barren rock cover ratio was high. On the closed trail, litter rock barren cover ratio of the closed trail was recovered, but only limited recovery was found on vegetation cover by applying environmental damage condition rating class. In conclusion, the closed trail was recovered by designation of special protection area, while difference in recovery progress of soil and vegetation was found. Therefore, designation of special protection area of degraded area should be based on scientific basis of recovery characteristics of the area. In order to improve the effectiveness of special protection area system, further specific standards for special protection area designation and management would be needed, considering ecological and social importance of target areas.

• Horticultural Science & Technology
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• v.16 no.4
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• pp.517-519
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• 1998

This experiment was carried out to find out the effects of heat conservation materials (burying in soil, lagging, lagging +straw, nonwoven fabric, nonwoven fabric+straw) on freezing damage, labor saving, and crown gall occurrence of 'Kyoho' grapes. Temperature differences in burying in soil and lagging with $2.8^{\circ}C$ and $6.4^{\circ}C$, respectively and were considered favorable for over-wintering of grapevines. Heat conservation index in lagging +straw and burying in soil calculated from degree-hours below $-10^{\circ}C$ was 5 to 7 times higher than that of open field. Budbreak started earlier in lagging with+straw and nonwoven fabric+straw covering, and percent budbreak was increased by 22% and 7%, respectively, as well as higher than burying in soil. Diameter of bearing mother branch and length of internode and daughter branch were gross or long with soil and lagging straw and nonwoven fabric+straw. Cane growth was enhanced by burying in soil and lagging with+straw treatment. Crown gall occured higher in soil covered grape vines Labor saving was obtained in lagging with as much as 44% compared to burying in soil.