• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.151-165
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• 2021

This paper aims to present a novelty damage detection method to identify damage locations by the simultaneous use of both the energy and displacement damage indices. Using this novelty method, the damaged location and even the damaged floor are accurately detected. As a first method, a combination of the instantaneous frequency energy index (EDI) and the structural acceleration responses are used. To evaluate the first method and also present a rapid assessment method, the Displacement Damage Index (DDI), which consists of the error reliability (β) and Normal Probability Density Function (NPDF) indices, are introduced. The innovation of this method is the simultaneous use of displacement-acceleration responses during one process, which is more effective in the rapid evaluation of damage patterns with velocity vectors. In order to evaluate the effectiveness of the proposed method, various damage scenarios of the ASCE benchmark problem, and the effects of measurement noise were studied numerically. Extensive analyses show that the rapid proposed method is capable of accurately detecting the location of sparse damages through the building. Finally, the proposed method was validated by experimental studies of a six-story steel building structure with single and multiple damage cases.

• Journal of the Korean Solar Energy Society
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• v.23 no.1
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• pp.57-67
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• 2003

This study aims to presents Evaluation Method of Green Remodeling that analyze the value of environment through expense, using the method of life cycle cost and life cycle assessment simultaneously. The results of this study are summarized as follows. Evaluation Model developed in this study can convert economical value of environment into cost by integrating. In addition, the model can apply as a useful tool to estimation of economical design alternative as well as quantification of environmental loads and costs. Evaluation Model presented In this study observe energy consumption and the environmental load emission with qualification, it can forecast effect of environmental cost that cost estimation is expected to be added to energy cost rate by being possible. Synthetically, when Estimation Model and computer program that developed in this study is applies to the construction industry; reasonable management of environmental load is convenient at each step of Green Remodeling. In addition, at preliminary design phase, practical use may be possible by reasonable yardstick about various alternatives and improvement of design alternatives likewise by grasping environmental effect.

• Smart Structures and Systems
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• v.2 no.2
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• pp.127-140
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• 2006

In this study, a wavelet-based covariance-driven system identification technique is proposed for damage assessment of structures under ambient excitation. Assuming the ambient excitation to be a white-noise process, the covariance computation is shown to be able to separate the effect of random excitation from the response measurement. Wavelet transform (WT) is then used to convert the covariance response in the time domain to the WT magnitude plot in the time-scale plane. The wavelet coefficients along the curves where energy concentrated are extracted and used to estimate the modal properties of the structure. These modal property estimations lead to the calculation of the stiffness matrix when either the spectral density of the random loading or the mass matrix is given. The predicted stiffness matrix hence provides a direct assessment on the possible location and severity of damage which results in stiffness alteration. To demonstrate the proposed wavelet-based damage assessment technique, a numerical example on a 3 degree-of-freedom (DOF) system and an experimental study on a three-story building model, which are all under a broad-band excitation, are presented. Both numerical and experimental results illustrate that the proposed technique can provide an accurate assessment on the damage location. It is however noted that the assessment of damage severity is not as accurate, which might be due to the errors associated with the mode shape estimations as well as the assumption of proportional damping adopted in the formulation.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.111-117
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• 2006

Song-do City is a newly constructed city built on land reclaimed from the seaside and the surrounding area. Its development involved a long process since the basic plans for reclamation of the publicly owned seaside area in Song-do were drawn up in September 1979. However, if we take a look at the overall status of the project as it is carried on at present, it is hard to deny that the project is trapped inside the same legal restrictions as are all other existing cities, which permits Song-do City to meet only very minimum standards. This study intends to analyze and assess the Song-do City's environmentally friendly construction and to rate its current development status, exposing any problems and offering alternative solutions. In this paper, the current state of constructions in Song-do City were reviewed. Then a quantitative analysis and assessment for the Song-do City constructions of apartments, complex buildings, office buildings, and school facilities were conducted by using green building certification criteria. Finally the synthetic results of environmental performance evaluation for Song-do city constructions and follow-up suggestions were described.

• Journal of the Korea Institute of Building Construction
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• v.15 no.1
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• pp.107-113
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• 2015

Recently mechanization construction methods are developed rapidly in the field of construction processing. The construction industry is one of the sector that still requires a lot of manual labor of the entire industry. There are still various kinds of work done by human labors, especially in the disassembling and separation of materials for recycling. However, database of relevant statistics including estimating standards are difficult to analyze by actual human workload, and furthermore the disassembling processes are being analyzed by qualitative assessment. This study attempted to introduce the accelerometer for the quantitative evaluation of human workload in the construction field. Still, it is possible to calculate the amount of energy which is required for the assembling and disassembling of nail and screw through three-dimensional accelerometer.

• KIEAE Journal
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• v.11 no.6
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• pp.81-86
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• 2011

By strengthening the insulation performance of a building, a great deal of energy can be saved and a comfortable indoor environment can be offered to people. On the other hand, the climate, which has a great influence on the indoor environment, is changed by global warming. Therefore, in planning building envelope structure and design, climate change should be considered. In this paper, the optimal insulation thickness of exterior walls was calculated by an economic assessment method using heating degree-days. Additionally, how much influence climate change has on planning building insulation was investigated. The examination showed that heating degree-days have decreased by about 10% due to climate change in the past few decades. It was also shown that the optimal insulation thickness of exterior walls was thin, at about 6%, in three representative Korean cities (Seoul, Daejeon, Jeju).

• Journal of Power System Engineering
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• v.17 no.4
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• pp.131-138
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• 2013

The purpose of this study is to suggest the evaluation standard of cost-effectiveness analysis for renew of architectural equipment in public building. Evaluation items of cost-effectiveness analysis for renew of architectural equipment in public building were used life cycle cost, energy consumption(ton of oil equivalent), green house gas emissions(ton of carbon dioxide) and maximum power demand. Life cycle cost is the process of making an economic assessment of an item, area, system, or facility by considering all significant costs of ownership over an economic life, expressed in terms of equivalent costs. The essence of life cycle costing is the analysis of equivalent costs of various alternative proposals. The social concern with green house gas and maximum power demand of architectural equipment field has been growing for the last several years.

• Steel and Composite Structures
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• v.13 no.6
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• pp.501-519
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• 2012

As an alternative to current conventional force-based assessment methods, the energy-based seismic performance of a code-designed 20-storey high-rise steel building is evaluated in this paper. Using 3D nonlinear dynamic time-history method with consideration of additional material damping effect, the influences of different restoring force models and P-${\Delta}/{\delta}$ effects on energy components are investigated. By combining equivalent viscous damping and hysteretic damping ratios of the structure subjected to strong ground motions, a new damping model, which is amplitude-dependent, is discussed in detail. According to the analytical results, all energy components are affected to various extents by P-${\Delta}/{\delta}$ effects and a difference of less than 10% is observed; the energy values of the structure without consideration of P-${\Delta}/{\delta}$ effects are larger, while the restoring force models have a minor effect on seismic input energy with a difference of less than 5%, but they have a certain effect on both viscous damping energy and hysteretic energy with a difference of about 5~15%. The paper shows that the use of the hysteretic energy at its ultimate state as a seismic design parameter has more advantages than seismic input energy since it presents a more stable value. The total damping ratio of a structure consists of viscous damping ratio and hysteretic damping ratio and it is found that the equivalent viscous damping ratio is a constant for the structure, while the equivalent hysteretic damping ratio approximately increases linearly with structural response in elasto-plastic stage.

• Structural Engineering and Mechanics
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• v.87 no.6
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• pp.555-574
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• 2023

An efficient optimization algorithm and damage-sensitive objective function are two main components in optimization-based Finite Element Model Updating (FEMU). A suitable combination of these components can considerably affect damage detection accuracy. In this study, a new hybrid damage-sensitive objective function is proposed based on combining two different objection functions to detect the location and extent of damage in structures. The first one is based on Generalized Pseudo Modal Strain Energy (GPMSE), and the second is based on the element's Generalized Flexibility Matrix (GFM). Four well-known population-based metaheuristic algorithms are used to solve the problem and report the optimal solution as damage detection results. These algorithms consist of Cuckoo Search (CS), Teaching-Learning-Based Optimization (TLBO), Moth Flame Optimization (MFO), and Jaya. Three numerical examples and one experimental study are studied to illustrate the capability of the proposed method. The performance of the considered metaheuristics is also compared with each other to choose the most suitable optimizer in structural damage detection. The numerical examinations on truss and frame structures with considering the effects of measurement noise and availability of only the first few vibrating modes reveal the good performance of the proposed technique in identifying damage locations and their severities. Experimental examinations on a six-story shear building structure tested on a shake table also indicate that this method can be considered as a suitable technique for damage assessment of shear building structures.

• Structural Engineering and Mechanics
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• v.73 no.6
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• pp.699-714
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• 2020

Force based design (FBD) approach is prevalent in most of the national seismic design codes world over. Direct displacement based design (DDBD) and energy based design (EBD) approaches are relatively new methods of seismic design which claims to be more rational and predictive than the FBD. These three design approaches are conceptually distinct and imparts different strength, stiffness and ductility property to structural members for same plan configuration. In present study behavioural assessment of frame of six storey RC building designed using FBD, DDBD and EBD approaches has been performed. Lateral storey forces distribution, reinforcement design and results of nonlinear performance using static and dynamic methods have been compared. For the three approaches, considerable difference in lateral storey forces distribution and reinforcement design has been observed. Nonlinear pushover analysis and time history analysis results show that in FBD frame plastic deformation is concentrated in the lower storey, in EBD frame large plastic deformation is concentrated in the middle storeys though the inelastic hinges are well distributed over the height and, in DDBD frame plastic deformation is approximately uniform over the height. Overall the six storey frame designed using DDBD approach seems to be more rational than the other two methods.