• Journal of Ocean Engineering and Technology
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• v.35 no.6
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• pp.414-425
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• 2021

Overcrowding of high-rise buildings in urban zones change the airflow pattern in the surrounding areas. This causes building wind, which adversely affects the wind environment. Building wind can generate more serious social damage under extreme weather conditions such as typhoons. In this study, to analyze the wind speed and wind speed ratio quantitatively, we installed five anemometers in Haeundae, where high-rise buildings are dense, and conducted on-site monitoring in the event of typhoon OMAIS to determine the characteristics of wind over skyscraper towers surround the other buildings. At point M-2, where the strongest wind speed was measured, the maximum average wind speed in 1 min was observed to be 28.99 m/s, which was 1.7 times stronger than that at the ocean observatory, of 17.0 m/s, at the same time. Furthermore, when the wind speed at the ocean observatory was 8.2 m/s, a strong wind speed of 24 m/s was blowing at point M-2, and the wind speed ratio compared to that at the ocean observatory was 2.92. It is judged that winds 2-3 times stronger than those at the surrounding areas can be induced under certain conditions due to the building wind effect. To verify the degree of wind speed, we introduced the Beaufort wind scale. The Beaufort numbers of wind speed data for the ocean observatory were mostly distributed from 2 to 6, and the maximum value was 8; however, for the observation point, values from 9 to 11 were observed. Through this study, it was possible to determine the characteristics of the wind environment in the area around high-rise buildings due to the building wind effect.

• Journal of Soil and Groundwater Environment
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• v.27 no.spc
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• pp.19-33
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• 2022

When subsurface is polluted, contaminants tend to migrate through groundwater flow path. The groundwater flow path is highly dependent upon underground geological structures in the contaminated area. Geophysical survey is an useful tool to identify subsurface geological structure. In addition, geophysical logging in a borehole precisely provides detailed information about geological characteristics in vicinity of the borehole, including fractures, lithology, and groundwater level. In this work, surface seismic refraction and electrical resistivity surveys were conducted in a test site located in Namyangju city, South Korea, along with well logging tests in five boreholes installed in the site. Geophysical data and well logging data were collected and processed to construct an 3D geological map in the site.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.276-285
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• 2006

Application of anchored or strutted wall system for the earth retention of excavation works in a populated urban area or a poor soil deposit can be limited due to various restrictions. Since the strut becomes longer in a wide excavation site, the stability of an earth retaining wall is decreased, the wall deformation is increased, and the ground settlement is also increased due to an increased buckling or bending deformation of struts. Especially, in a populated urban area, the installation of anchors can be problematic due to the property line of adjacent structures or facilities. Thus, a new concept of earth retaining system like Self-Supported diaphragm Wall can solve several problems expected to occur during excavation in the urban area. In this study, Numerical analyses of counterfort diaphragm wall was introduced and the monitored data from the site was compared with the original results of numerical analyses. Also, in the case of the deep excavation applied the counterfort diaphragm wall, numerical analyses was performed to predict the wall deformation and the reinforcement to reduce the wall deformation was suggested.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.869-877
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• 2016

Necessity has compelled man to improve upon the art of tapping wind energy for power generation; an apt reliever of strain exerted on the non-renewable fossil fuel. The power generation in a Wind Farm (WF) depends on site and wind velocity which varies with time and season which in turn determine wind power modeling. It implies, the development of an accurate wind speed model to predict wind power fluctuations at a particular site is significant. In this paper, Box-Jenkins ARIMA (Auto Regressive Integrated Moving Average) time series model for wind speed is developed for a 99MW wind farm in the southern region of India. Because of the uncertainty in wind power developed, the economic viability and reliability of power generation is significant. Life Cycle Costing (LCC) method is used to determine the economic viability of WF generated power. Reliability models of WF are developed with the help of load curve of the utility grid and Capacity Outage Probability Table (COPT). ARIMA wind speed model is used for developing COPT. The values of annual reliability indices and variations of risk index of the WF with system peak load are calculated. Such reliability models of large WF can be used in generation system planning.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.602-603
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• 2015

Despite all efforts to reduce construction disaster, construction site accident rate has steadily increased in Korea since 2008. As a different approach from traditional research, there is a growing issue about design for safety concept to prevent construction disaster. The notion is that construction worker's safety need to be considered at design phase, not only at construction phase. Globally, the notion has been noted that to improve the safety of the worker and used in practice. However, in Korea, most of safety management guidelines are limited to construction phase. From recent statistics, only 1.4 percent of designer feel responsible for safety accident at construction site. In this circumstance, this research find out safety guidelines through literatures reviews and practical experience of safety management in other country which apply design for safety concept. Selected guidelines are verified by survey which is evaluated with risk, function, cost, time and aesthetic view categories. Through the survey, define guidelines which could be effectively applied in Korea. By using proposed safety guidelines for design phase, preventing construction accident and improving designer's recognition of safety issue at design phase are expected.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.665-666
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• 2015

Recently BIM technology has been expanded for using in construction project. However its spread has been delayed than the initial expectations, due to the high-cost of BIM infrastructure development, the lack of regulations, the lack of process and so forth. In construction site phase, especially the analysis of current research trend about IT technologies, virtualization and BIM service, data exchange such as drawing, 3D model, object data, properties using cloud computing and virtual server system is defined as a most successful solution. The purpose of this study is enable the cloud computing BIM server to provide several main function such as edit a model, 3D model viewer and checker, mark-up, snapshot in high-performance quality by proper design of VDI system. Concurrent client connection performance is a main technical index of VDI. Through test-bed server client, developed VDI system's multi-connect control will be evaluated. The performance-test result of BIM server VDI will effect to development direction of cloud computing BIM service for commercialization.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.193-200
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• 1999

An experimental study is described in which a 305-mm-diameter instrumented drilled shaft was installed in a moderately expansive clay soil during the dry season and monitored over a period of about 18 months. The purpose of the study was In investigate the effects of seasonal moisture changes in the soil on the shear stresses imposed on the sides of the drilled shaft and movements of the shaft head. The soil in the vicinity of the test shaft was instrumented to measure suction and ground surface movement and the relation between suction, total stress and shear strength of the soil at the test site was determined through laboratory triaxial compression testing. Daily rainfall and temperatures were also monitored at the test site, the National Geotechnical Experimentation Site at the University of Houston, where control on surface grading and vegetation existed. Over the course of the study induced unit side shear values of up to 54 kPa were measured in the test shaft. A simple computational model was developed that related observed suction changes to unit side shear induced by the expansion of the soil through the use of the laboratory suction-total stress-shear strength relation.

• Korean Journal of Construction Engineering and Management
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• v.9 no.2
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• pp.90-98
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• 2008

The technical improvement of high-rise building construction is getting better as the demands of the skyscrapers is increasing. The interior construction has become the essential factor which directly affects the whole project because of skyscraperization. This study has proposed the site image-based space model as the tool for supporting decision-making for preparation and execution of the interior construction. It is expected to make the space model which is suitable for the project characteristics and work packages.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.3
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• pp.151-160
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• 2014

Probabilistic tsunami hazard analysis (PTHA) is based on the approach of probabilistic seismic hazard analysis (PSHA) which is performed using various seismotectonic models and ground-motion prediction equations. The major difference between PTHA and PSHA is that PTHA requires the wave parameters of tsunami. The wave parameters can be estimated from tsunami propagation analysis. Therefore, a tsunami simulation analysis was conducted for the purpose of evaluating the wave parameters required for the PTHA of Uljin nuclear power plant (NPP) site. The tsunamigenic fault sources in the western part of Japan were chosen for the analysis. The wave heights for 80 rupture scenarios were numerically simulated. The synthetic tsunami waveforms were obtained around the Uljin NPP site. The results show that the wave heights are closely related with the location of the fault sources and the associated potential earthquake magnitudes. These wave parameters can be used as input data for the future PTHA study of the Uljin NPP site.

• Journal of Soil and Groundwater Environment
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• v.22 no.5
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• pp.48-62
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• 2017

Korea and other countries have made various efforts to preserve soil. During the past several decades, Korea has implemented various policies on soil conservation practices; however, those policies have often lacked consideration of human and ecosystem risk management. while other countries have practiced various policies closely related to risk-based management for contaminated sites. Therefore, there is a great need for a paradigm shift of policy to better manage contaminated sites in risk-based strategies, while applying different management plans for soil and groundwater. In addition, the new policies should be administered with provision to improve soil health and related functions in ecosystem. This study has reviewed the trend in relevant policies in Korea and foreign countries to suggest the future policy directions for contaminated site management in Korea. For better management of contaminated sites, coherent policy that could complement the law, system, and relevant technology is required.