• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.297-300
• /
• 2008

Friction coefficients of the prestressing tendon are the basic information required to control the prestressing force introduced to PSC structure during jacking. However, the friction coefficients show considerable differences depending on the specifications, causing much confusion to designers. In this study, a procedure is proposed that can be used to estimate the wobble and curvature friction coefficients from field data and classical theory related to the friction. The procedure is applied to two PSC girder bridges with various tendon profiles. The resulting values are compared with those presented in some specifications and assumed in jacking. The resulting wobble friction coefficients are not as small as those presented in AASHTO specifications but are more or less similar to the lower limit of domestic standards, while the curvature friction coefficients approach or slightly exceed the upper limit of the same standards.

• Korean Journal of Construction Engineering and Management
• /
• v.6 no.4 s.26
• /
• pp.164-171
• /
• 2005

The importance of the life cycle cost analysis(LCCA) for apartment housing remodeling projects has been fully recognized over the last decade. Accordingly theoretical models, guidelines, and supporting software systems were developed for the life cycle cost analysis of apartment housing remodeling systems. However, the level of consensus on LCCA results is still low due to the lack of reliable data on remodeling activities for safety diagnosis. in order to predict the reliability based LCCA of the given case, suggested the remodeling strategies level after reviewing other related materials. Apply the real information of the economic index. And based on such analytical measures, remodeling and operation cost and LCC in remodeling strategies level have been predicted; suggests the basic information about remodeling interventions level for the apartment housing. The LCC analysis models and the fuzzy logic based safety assessment presented in this study can greatly contribute to the value-oriented design alternative selection, estimation of the economic analysis, and the allocation of budget for apartm.

• Journal of the Korean Geographical Society
• /
• v.39 no.3
• /
• pp.360-373
• /
• 2004

The purpose of this study is establishing how to build the area of local agents and regional offices in the oil company using GIS technique by reviewing on the spatial distribution pattern and characteristics of the sales area of oil products. Location-allocation and spatial interaction model are cooperated in order to establish sales area of petroleum products distribution system. Location-allocation model is used in the capital region where local agents are concentrated on like Kyoung-gi local agent. Spatial interaction model is used in the rest of the area in Korea to analyze the sales range of the regional offices in oil company. Each office made a big difference in registered cars and population because of the level of petroleum consumption in each sales area.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2004.11a
• /
• pp.476-479
• /
• 2004

In the process of industrialization of our country in 1970's, Korea's housing strategy has focused on housing supply. Rapid completion and supply of apartment house buildings have caused a problem of their early deterioration due to their poor quality. In 1987 Housing Construction Promotion Act, therefore, included new regulations on housing re-construction. In July 2001, other new regulations on remodeling apartment buildings were also included in the Act. Reconstruction and remodeling have been considered to deal with such problems. This study suggests an appraisal criteria if they can select reconstruction or remodeling method in conducting their apartment building project. At first, evaluation items should be selected by the criteria of function31ity and economical efficiency. Second, the selected item is screened by AHP and multi-criteria decision-making methods. The result of study shows that the owners of apartment units will be able to select reasonable alternatives through the suggested appraisal method

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.5
• /
• pp.173-181
• /
• 1993

Under natural conditions, rivers do not in general take straight courses but instead take winding courses. This is known as meandering of rivers. Meandering of rivers are so complicated because of the mutual interactions between flow and movable boundaries. In quantitative information, it is important to predict the future location of a river channel(channel migration) because in selecting a bridge site or a location of a road. It may be valuable to know the future impact of a nearby river on those structures. When the prediction model of the migration of channel is used in domestic rivers with high coefficient of river regime, it is rational to use the periodical dominant discharge (PDD), which is named firstly by the author, instead of the average discharge. According to the analysis of the erosion coefficient, the mean deviation on the channel migration, and the bed scour factor, it can bring shedding light on the fact that the discharge is one of the dominant components in channel migration. In project area, the discharge that can shift the channel is slightly greater than 6,000CMS. The prediction model of the migration of channel estimated the erosion coefficient, $E_0$ by the data from the South Han River. This estimated value from the South Han River was also used to predict the migration of the South Han River in year 2000.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.2
• /
• pp.149-156
• /
• 2017

Nuclear fuel requires high reliability and safety and therefore contains debris filtering devices to prevent failure-inducing debris from entering it. The debris filtering performance of nuclear fuel is one of the most important factors for fuel integrity. Therefore, the performance must be evaluated and the measurement must be reasonable. In this study, a calculation method of the comprehensive filtering efficiency using the weighted mean was proposed to establish a standard filtering efficiency index. To confirm the suitability of the proposed method, representative debris specimens were selected and the filtering efficiency with the weighted mean was compared with the efficiency of the arithmetic mean. The weighting factor of the weighted mean was introduced to produce a fair evaluation. In addition, the analysis of the debris filtering mechanism was performed according to the size of debris specimens, and the main dimensions of the filtering feature for commercial nuclear fuel.

• Spatial Information Research
• /
• v.13 no.1 s.32
• /
• pp.1-17
• /
• 2005

This paper draws new guidelines on the current method in Land Suitability Assessment (LSA), enforced to identify potential of parcels .elated to agricultural productivity, preservable value, and economic viability. In order to make recommendations of current LSA methodology, this study analyzes the issues related to the parcel-based LSA and addresses its inappropriateness f3r incorporating characteristics of each parcel. Through case studies and sensitivity analyses using GIS, the results show that (1) the $10\times10m$ grid-based LSA is much better assessment method than parcel-based one, because it gives detailed informations on attributes of each parcel; (2) more than one-distance factor should be taken into account to calculate the appropriate potential measure; and (3) the characteristics of public facilities or urbanized areas including size, density, and land use should be incorporated into the attraction variable of ny Potential model. Finally future research areas are outlined.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.15 no.6
• /
• pp.11-18
• /
• 2011

Accurate modal identification analysis is required to reasonably perform a seismic qualification of safety-related electric equipment installed in nuclear power plants (NPPs). This study evaluates a variation of the modal properties of an electric equipment cabinet structure in NPPs according to the excitation levels. For the study, an actual electric equipment cabinet was selected as a specimen and was dynamically tested by using a portable exciter in accordance with the level of input vibration energy. Tests were classified into two sets: with-door cases, and without-door cases. Frequency response functions were computed from the signals of the acceleration responses and input motions measured from the vibration tests. A polynomial curve fitting algorithm was used to extract the modal properties from the frequency response functions. This study reviews the variation of the modal properties according to the variation of the excitation levels. The results of the study show that the modal frequencies and the modal dampings of the object specimen varies nonlinearly according to the excitation level of the test motion. Attaching the door increases the modal damping of the cabinet.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1267-1272
• /
• 2007

In the case of the railway bridge, there are following the progress of works after the drainage method of a bridge surface - vibration proof rubber establishment, track gravel construction and rail construction etc. But these works are not enforced consecutively by the execution and economical reason. This is the reason of the long period of exposure after drainage execution. In many case, from the deterioration phenomenon by long term exposure of surface, there are a lot of occasions that do not keep primitive penetration depth waterproof primitive time. It is the most important that select the drainage method that have durability - it is not fallen in long-term exposure of surface. The major objective of this study is to deduce objective analysis result through examination about the Deterioration Restraining Agent method and to master KNOW-HOW of DRA drainage method. Through the study, minimize economical damage by frequent repair and reinforcement and present the reasonable standard of judgement fot drainage method of construction.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1647-1656
• /
• 2007

With the growing international consensus regarding sustainable development of transportation, the plan of transportation infrastructure needs to meet various requirements toward enhancing environmental conditions. Accordingly, the upcoming long-term plan of high-speed rail network has to be reflecting the sustainability of transportation systems. In this paper, we propose methodologies based on multi-attribute utility theory for determining priorities of sustainable high-speed rail investment. The proposed methodologies identify indicators for sustainable transportation systems such as economic, environmental, social, and transportation-related ones and then, explain the way how to evaluate the overall sustainability by comparing the relative importance among indicators. This will help transportation agencies to prioritize high-speed rail investment toward sustainable transportation systems.