• Wind and Structures
• /
• v.32 no.5
• /
• pp.501-508
• /
• 2021

The turbine industry demands a reliable design with affordable cost. As technological advances begin to support turbines of huge sizes, and the increasing importance of wind turbines from day to day make design safety conditions more important. Wind turbines are exposed to environmental conditions that can affect their installation, durability, and operation. International Electrotechnical Commission (IEC) 61400-1 design load cases consist of analyses involving wind turbine operating conditions. This design load cases (DLC) is important for determining fatigue loads (i.e., forces and moments) that occur as a result of expected conditions throughout the life of the machine. With the help of FAST (Fatigue, Aerodynamics, Structures, and Turbulence), an open source software, the NREL 5MW land base wind turbine model was used. IEC 61400-1 wind turbine design standard procedures assessed turbine behavior and fatigue damage to the tower base of dynamic loads in different design conditions. Real characteristic wind speed distribution and multi-directional effect specific to the site were taken into consideration. The effect of these conditions on the economic service life of the turbine has been studied.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.46-53
• /
• 2001

Differing Site Conditions('DSC') Claims among construction claims are on the increase as a direct result of the steady construction of Social Overhead Capital Facilities initiated by Government. As DSC claims generally became apparent during the intial stage of the construction project, it is necessary to timely review and study the proposal on the prevention of DSC claims because delayed settlement will incur more substantial damages to all parties concerned. This research is focused on the identification and analysis of the causes for DSC claims as applicable to design-build project in public sector and it presents the possible short term, medium and long term proposals on the improvement of causes related with DSC claims. The major results of this research are summarized as follows: 1. Improvement of contractor's tender practice 2. Contractor's division of responsibility on the site survey 3. Improvement of owner's exculpatory clause 4. Flexibility on the adjustment of contract amount The proposals stated above could be useful in resolving the DSC claims between owner and contractors.

• Fire Science and Engineering
• /
• v.23 no.4
• /
• pp.120-129
• /
• 2009

Identification of the exact cause of a building fire is generally difficult, because the source and initially ignited objects are often severely damaged or even lost during the early stages of the fire. We made an experimental attempt to reasonably estimate the burning during the very early stages of a fire, and identify its source and causes. The case we studied was an apartment fire, which occurred in Tokyo, in July 2002. The fire was extinguished just after flashover, and the on-site investigations suggested the fire started from the TV and TV stand, which had been damaged so severely that it was difficult to conclude that the TV was the ultimate cause of the fire, simply from the on-site investigation. We conducted a series of burn tests using a TV and other products identical to those actually used in the apartment. Tests were set-up and procedures were carefully studied to recreate the conditions of the articles that remained, and of the room itself. The tests demonstrated that the conditions in the apartment could be recreated only when the fire started inside the TV and came into close contact with dresser.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.34 no.2
• /
• pp.55-62
• /
• 2016

In this paper, Fengshui Theory Analysis Eunpyeong-New Town. The analysis frame is man and nature integrated, suit one measures to local conditions, analysis of macro environment site selection, analysis of micro environment site selection, analysis of traffic lines, orientations of residential analysis. The result is as follows: The analysis of the macro environment site selection of Eunpyeong-New Town at Northwest Mountain shape is open, so in the winter exposure of the northwest there is wind. Therefore, according to Fengshui there is a bad pattern formation. Analysis of the macro environment site selection has four animal frames seperated into two districts. The result is district one has "bad" ground. District two uses Bibo to restore small brooks so the formation has "good" ground. Finally, we use Fengshui of Bibo to propose solutions.

• Structural Engineering and Mechanics
• /
• v.70 no.2
• /
• pp.143-152
• /
• 2019

In this study, stochastic responses of a cable-stayed bridge subjected to the spatially varying earthquake ground motion are investigated for variable local soil cases and wave velocities. Quincy Bay-view cable-stayed bridge built on the Mississippi River in Illinois, USA selected as a numerical example. The bridge is composed of two H-shaped concrete towers, double plane fan type cables and a composite concrete-steel girder deck. The spatial variability of the ground motion is considered with the coherency function, which is represented by the components of incoherence, wave-passage and site-response effects. The incoherence effect is investigated by considering Harichandran and Vanmarcke model, the site-response effect is outlined by using hard, medium and soft soil types, and the wave-passage effect is taken into account by using 1000, 600 and 200 m/s wave velocities for the hard, medium and soft soils, respectively. Mean of maximum response values obtained from the analyses are compared with those of the specific cases of the ground motion model. It is concluded that the obtained results from the bridge model increase as the differences between local soil conditions cases of the bridge supports change from firm to soft. Moreover, the variation of the wave velocity has important effects on the responses of the deck and towers as compared with those of the travelling constant wave velocity case. In addition, the variability of the ground motions should be considered in the analysis of long span cable-stayed bridges to obtain more accurate results in calculating the bridge responses.

• International conference on construction engineering and project management
• /
• 2011.02a
• /
• pp.187-194
• /
• 2011

Optimizing truck dispatching-intervals is imperative in ready mixed concrete (RMC) delivery process. Intervals shorter than optimal may induce queuing of idle trucks at a construction site, resulting in a long delivery cycle time. On the other hand, intervals longer than optimal can trigger work discontinuity due to a lack of available trucks where required. Therefore, the RMC delivery process should be systematically scheduled in order to minimize the occurrence of waiting trucks as well as guarantee work continuity. However, it is challenging to find optimal intervals, particularly in urban areas, due to variations in both traffic conditions and concrete placement rates at the site. Truck dispatching intervals are usually determined based on the concrete plant managers' intuitive judgments, without sufficient and reliable information regarding traffic and site conditions. Accordingly, the RMC delivery process often experiences inefficiency and/or work discontinuity. Automatic data collection (ADC) techniques (e.g., RFID or GPS) can be effective tools to assist plant managers in finding optimal dispatching intervals, thereby enhancing delivery performance. However, quantitative evidence of the extent of performance improvement has rarely been reported to data, and this is a central reason for a general reluctance within the industry to embrace these techniques, despite their potential benefits. To address this issue, this research reports on the development of a discrete event simulation model and its application to a large-scale building project in Abu Dhabi. The simulation results indicate that ADC techniques can reduce the truck idle time at site by 57% and also enhance the pouring continuity in the RMC delivery process.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.33 no.4 s.111
• /
• pp.143-154
• /
• 2005

The Seoul Housing Corporation pronounced a design competition for Eunpyeng New Town District 2 in March of 2005. The authors collaborated on this design and won rot prize. Design guidelines of this competition were to make environmentally sustainable design, to develop as a resort site and cultural place for everyday life of residents, to link with green fabric of the district, and to elevate positive image and identity of Eunpyeng New Town district by creating a attractive landscape. The authors developed design concept and strategy within the guidelines and site conditions. The environmental setting of this site was characterized by mountain to the rear of the site with a stream passing through the district and the front of the site. This is the most important condition for the location principle of residence in Fung Shui theory. Therefore, the schema of the design was introduced by Fung Shui and Chi of place. To evolve design concept, we reinterpret the Fung Shui and Chi in the site combining with modem landscape design strategy, so that good place making could bring about well-being life of residents. By doing that, design concept of the proposal evolved as follows: 'fullness of comfortable life', 'adaptation of nature', 'inspiration of natural force'. This design approach is critical reevaluation of regional characters employing modem strategy. It is a conscious strategy of critical regionalism as distinguished from the traditional site oriented approach. The following are some of the major features in the design: green network and water recycle system in the site, promenade of forest with the experience nature, link to community core, theme gardens with plants having strong fragrances, terrace gardens with different level of housing type, playgrounds and resting places with many types, human scale facilities for residents.

• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.12
• /
• pp.792-800
• /
• 2012

The study was performed to simulate the reduction efficiency of suspended solids (SS) for cultivated land located at riverine area at the Namhan River and the Bukhan River watershed sites (site A, B, C) under the rainfall conditions using HUFF & SCS UH-based VFS Design module of Web GIS-based VFSMOD System. The study indicates that the field 5% sloped, located at Bukhan River watershed (site A), requires at least 0.5 m width of Vegetative Filter Strip (VFS) to reduce 70% of SS while the field 10% sloped requires the at least 1.0~1.5 m width of VFS to reduce 70% SS, under the condition 106.2 mm of rainfall event and bell pepper or corn of crops. Against the conditions 95.1 mm of rainfall event and sweet potato or soy bean of crops, the field 5% sloped, located at Namhan River watershed (site B) requires at least 0.5 m width of VFS to reduce 70% of SS while the field 10% sloped requires at least 1.0 m width of VFS to reduce 50% SS. The crops sweet potato and soy bean are cultivated in the site C, located at Namhan River watershed, 1 m of VFS is capable of 64.0% and 62.0% of SS reduction against 102.6 mm and 151.2 mm rainfall conditions respectively, for the 5% sloped field. The result supports that VFS is one of most potential methods to reduce SS from cultivated area, which is environment-friendly hydrologic structure. The VFS design, however, needs to be simulated before its installation in the field, the simulation needs to consider not only various characteristics of the field but also different conditions affecting the VFS, using a model capable to consider a lot of factors.

• Journal of Soil and Groundwater Environment
• /
• v.17 no.3
• /
• pp.21-31
• /
• 2012

This paper presents the short-term and long-term measures to determine the fugitive dust concentration in a contaminated site, which is a crucial step for the determination of particulate emission factor (PEF) for risk assessment. As a long-term measure, USEPA method employing Q/C value (inverse of the ratio of the geometric mean air concentration to the emission flux at center of a 0.5-acre square source) seems to be suitable as it reflects regional-specific meteorological conditions. However, it requires nation-wide database collection and interpretation. Use of ASTM method is an alternative as a short-term measure. The method is readily field-applicable as PEF calculation equation is simple and input parameters can be easily derived at the site of interest as well without the nation-wide efforts. Using ASTM method, PEF at the Former Janghang Smelter Site was determined. According to various mode of aggregate size distribution and fractions of vegetative cover, which are the most important factors in PEF calculation, PEF values at the Former Janghang Smelter Site varied greatly. When the mode of aggregate size distribution was set at 0.25 mm, PEF values at the Former Janghang Smelter Site was 5~20 times higher than the default PEF value (i.e., 35 ${\mu}g/m^3$) shown in the current Korean Soil Contamination Risk Assessment Guidance. On contrast, when the mode was set at 2 mm, PEF values at the Former Janghang Smelter Site was 160~640 times lower than the default PEF value in the Korean Guidance.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.06a
• /
• pp.93-101
• /
• 2003

Steel frame-type retaining walls(SFRW) are constructed by on site bolting of prefabricated steel frames and internal filling of materials such as rocks with the size of 150-300mm. Easy & fast construction, superior drainage performance and structural performance to rigorous site conditions are some of the merits of applying the SFRW to various construction sites. After the development of the structural details, a test construction of SFRW, with the height of 6m and 30m in length, was carried out at an apartment site. After completion, several months of monitoring was carried out on the structure to check displacement, tilting, settlement, soil pressures and drainage characteristics. The results of the structural behavior of SFRW along with its construction methods are presented in the paper.