• Journal of the Korean Geotechnical Society
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• v.36 no.7
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• pp.15-28
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• 2020

As the skin friction of an embedded pile is produced by the cement paste injected into the borehole, the skin friction cannot be evaluated by the end of initial driving test, which is conducted before the cement paste is cured. In addition, the total resistance of an embedded pile may not be properly evaluated during the restrike test if the base resistance is not fully mobilized because of the insufficient driven energy. The objective of this study is to suggest a new load-settlement curve of embedded piles by combining the results of the end of initial driving and restrike tests. Test piles are installed at fields by using the embedded pile method, and the results of the dynamic pile tests are analyzed using CAse Pile Wave Analysis Program (CAPWAP) after the end of initial driving and restrike tests are conducted. A new load transfer curve, which combines the behaviors of the pile base at the end of initial driving and of the pile shaft at the restrike, is suggested, and a new load-settlement curve is obtained. Subsequently, the resistances of the test piles are evaluated using the combined load-settlement curve, and compared with the results from the end of initial driving and restrike tests. The results showed that the resistances, which are evaluated using the combined load-settlement curve, may overcome the underestimation of the resistance because of the insufficient driven energy. In addition, the resistance resulted from the combined load-settlement curve may be more similar to that from the static load test because the suggested load transfer curve is closer to the behavior of the embedded pile compared to the results of end of initial driving and restrike tests. Therefore, this study demonstrates that the combined load-settlement curve may be effectively used for the evaluation of the bearing capacity of embedded piles.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1517-1522
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• 2018

This paper describes the improvement of the arithmetic for emergency generator capacity. This formula which calculates emergency generator is dependent on the Korean Design Standard of building electrical equipment issued by the Ministry of Land, Infrastructure and Transport, and the technical data related to the generator. when appling the formula, the capacity of the generator is insufficient at the starting conditions of the load facility. In case of emergency, the generator is not operated normally. $PG_2$ of the formula ($PG_1$, $PG_2$, $PG_3$) applied in determining the capacity of the emergency generator is selected by calculating the capacity of the generator based on only biggest one motor among the load equipment and $PG_3$ may not be able to start the generator normally in case of emergency because there is an error such that the power factor is applied at the last start of the motor having the maximum capacity of the load. We analyze the problem of capacity calculation of emergency generators used for general purposes. As a consequence, the improved formulas have been presented for safety of electrical installation.

• Geomechanics and Engineering
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• v.8 no.6
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• pp.769-781
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• 2015

The skin friction of a pile foundation is important and essential for its design and analysis. More attention has been given to the softening behaviour of skin friction of a pile. In this study, to investigate the load-transfer mechanism in such a case, an analytical solution using a nonlinear softening model was derived. Subsequently, a load test on the pile was performed to verify the newly developed analytical solution. The comparison between the analytical solution and test results showed a good agreement in terms of the axial force of the pile and the stress-strain relationship of the pile-soil interface. The softening behaviour of the skin friction can be simulated well when the pile is subjected to large loads; however, such behaviour is generally ignored by most existing analytical solutions. Finally, the effects of the initial shear modulus and the ratio of the residual skin friction to peak skin friction on the load-settlement curve of a pile were investigated by a parametric analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.896-901
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• 2009

A Soil Nail is a structural element which provides load-transfer to the ground in excavation reinforcement applications. The nail may simply consist of a steel tendon, but most commonly the tendon is encapsulated in a cement grouted body to provide corrosion protection and improved load- transfer to the ground. For temporary excavation support in a congested urban area, the steel bar of Soil Nails should be removed to get permission of the private land to install Soil Nails. Several removable nail systems were developed and evaluated by pull-out load tests. The Soil Nail pull-out tests were performed on five nails installed in soft and hard rock at a 00 housing-redevelopment area in seoul. Two nails are plastic socket type and two are complex socket type mixed steel and plastic. The nail was 0.1mm in diameter, 4m long. In this study verification tests, and steel bar removing tests of plastic socket type nails and complex socket type nails were performed and presented.

• Wind and Structures
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• v.28 no.6
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• pp.381-388
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• 2019

This paper described the application of Geospatial Analysis in determining mean wind speed, $V_h$ for wind load calculation imposed to electrical transmission tower structural design. The basic wind speed data on available station obtained from Malaysian Meteorology Department is adjusted by considering terrain and ground roughness factor. The correlation between basic wind speed, terrain factor and ground roughness stated in EN-50341-1 is used to obtain the $V_h$ for overhead transmission line elements 50 m above ground. Terrain factor, $k_r$ and ground roughness, $z_0$ in this study are presented by land use types of study area. Wind load is then calculated by using equation stated in design code EN-50341-1 by using the adjusted mean wind speed. Scatter plots of $V_h$ for different $k_r$and $z_0$ are presented in this paper to see the effect of these parameters to the value of $V_h$. Geospatial analysis is used to represent the model of $V_h$. This model can be used to determine possible area that will subject to wind load which severe to the stability of transmission tower and transmission line.

• Journal of the Korean Geographical Society
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• v.32 no.4
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• pp.463-478
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• 1997

This paper examines the impact of large-scale tidal flat reclamations on environment by analyzing land use change, ocean cultivation, water quality, sea biota and climate in Shiwha, Sosan and Saemankeum districts. The data used in this paper include Landsat TM images and documents related to population, industry, water quality, sea biota and climate at the time of the pre- and post-reclamation. Many times of field reclamations contribute to the creatation of newly available land for urban and industrial development, but cause environmental degradation significantly. The increase of pollution load and the change of coastal ecology, also cause some changes of climatic element such as relative humidity. As tidal flats were reduced, the area of ocean cultivation and the population of fishing industries were decreased. Conceming the sustainable development. it is necessary to carry out a careful environmental impact assessment accumulating monitoring environmental data continuously by using GIS techniques.

• Journal of Animal Science and Technology
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• v.60 no.2
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• pp.3.1-3.9
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• 2018

Background: Poultry breeding has increased by 306% in Korea, inevitably increasing the production of manure which may contribute to environmental pollution. The nutrients (NP) in the manure are essential for crop cultivation and soil fertility when applied as compost. Excess nutrients from manure can be accumulated on the land and can lead to eutrophication. Therefore, a nutrient load on the finite land should be calculated. Methods: This study calculates the nutrient production from Korean poultry by investigating 11 broiler and 16 laying hen farms. The broiler manure was composted using deep litter composting while for layer deep litter composting, drying, and simple static pile were in practice. The effect of weight reduction and storing period during composting was checked. Three weight reduction cases of compost were constructed to calculate nutrient loading coefficients (NLCs) using data from; i) farm investigation, ii) theoretical P changes (${\Delta}P=0$), and iii) dry basis. Results: During farm investigation of broiler and layer with deep litter composting, there was a 68 and 21% N loss whereas 77 and 33% P loss was found, respectively. In case of layer composting, a loss of 10-56% N and a 52% P loss was observed. Drying manure increased the P concentrations therefore NLCs calculated using dry basis that showed quite higher reductions (67% N; 53% P). Nutrient loss from farm investigation was much higher than reported by Korean Ministry of Environment (ME). Conclusions: Nutrients in manure are decreased when undergo storing or composting process due to microbial action, drying, and leaching. The nutrient load applied to soil is less than the fresh manure, hence the livestock manure management and conservation of environment would be facilitated.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.377-387
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• 2016

In recent, in case that the underpass is constructed by trenchless method, its stability increases by reinforcing steel pipe with re-bar and mortar after propulsion into the ground to form pipe-roof. Therefore, it can be predicted that the integrated pipe-roof decreases the stress acting on the underpass by sharing load. In this study, to analyze the effect of integrated pipe-roof and behavior of stress around underpass, experimental tests for the rectangular and arch cross section of the underpass are performed using soil chamber. As a result, stress and strain acting on the underpass decrease due to sharing load by integrated pipe-roof. This phenomenon is more pronounced by increasing the stiffness of pipe-roof. Furthermore it can be expected that cross-section of underpass can be economically designed.

• Land and Housing Review
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• v.2 no.4
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• pp.569-575
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• 2011

In domestic mechanical demolition work against RC building, unsuitable selection and loading of heavy equipment have led to occasional accidents such as collapse of structural members during the work. Therefore, proper analysis technique to easily decide allowable equipment load on the structure is needed at the planning stage of mechanical demolition work. In this paper, performing loading test and elastic analysis against 4-story building at full scale, we confirm appropriateness for allowable load of equipment on RC structures, which was suggested in previous study, and suggest structural analysis method that can evaluate safety of RC building during the mechanical demolition. The suggested method can be effectively utilized to improve work efficiency through safety of mechanical demolition work against RC building and proper management of equipments.

• Land and Housing Review
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• v.4 no.3
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• pp.295-301
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• 2013

In this study, cases of domestic tall residential buildings were investigated for the structural types, numbers of stories, total heights, type of lateral load resisting systems, and zoning of concrete strength. Based on these investigation data, the structural planning pattern of tall residential building was analyzed. SRC structure is main structural types of tall residential building at the initial stage of domestic tall residential building, but RC structure is substituted for main structural types since 2005. Retaining wall system is positioned at the core part of structural plan as a lateral load resisting system. Concrete strength zoning of vertical members like columns are divided by vertical heights of lower parts, middle parts, and upper parts. Basic data of structural planning of 40stories and 60 stories residential buildings was proposed based on case investigation.