• International Journal of High-Rise Buildings
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• v.1 no.3
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• pp.181-194
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• 2012

Chile is characterized by the largest seismicity in the world which produces strong earthquakes every $83{\pm}9years$ in the Central part of Chile, where it is located Santiago, the capital of Chile. The short interval between large earthquakes magnitude 8.5 has conditioned the Chilean seismic design practice to achieve almost operational performance level, despite the fact that the Chilean Code declares a scope of life safe performance level. Several Indexes have been widely used throughout the years in Chile to evaluate the structural characteristics of concrete buildings, with the intent to find a correlation between general structural conception and successful seismic performance. The Indexes presented are related only to global response of buildings under earthquake loads and not to the behavior or design of individual elements. A correlation between displacement demand and seismic structural damage is presented, using the index $H_o/T$ and the concrete compressive strain ${\varepsilon}_c$. Also the Chilean seismic design codes pre and post 2010 Maule earthquake are reviewed and the practice in seismic design vs Performance Based Design is presented. Performance Based Design procedures are not included in the Chilean seismic design code for buildings, nevertheless the earthquake experience has shown that the response of the Chilean buildings has been close to operational. This can be attributed to the fact that the drift of most engineered buildings designed in accordance with the Chilean practice falls below 0.5%. It is also known by experience that for frequent and even occasional earthquakes, buildings responded elastically and thus with "fully operational" performance. Taking the above into account, it can be said that, although the "basic objective" of the Chilean code is similar to the SEAOC VISION2000 criteria, the actual performance for normal buildings is closer to the "Essential/Hazardous objective".

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.643-651
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• 2014

In this paper the reliability analyses of the cable-supported bridge design code which is recently issued in Korea are performed and the results are presented. Governing load combinations for the member design and the statistical properties of the main members are introduced and the analysis is performed using an example cable-stayed bridge for which the design is performed following the load and resistance factors defined in the design code. The reliability analysis shows the target reliability index can be achieved by applying load and resistance factors and the application of the resistance modification factor can enhance the reliability level if the importance of the bridge needs to be increased. The sensitivity analysis reveals that decreasing uncertainty of the cable strength is critical for obtaining the target reliability index. The study results show that the design using the load and resistance factors of the code can achieve the target reliability indexes for the design of cable supported bridge.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.100-108
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• 2021

The purpose of this study is to analyze the reliability index of a design by applying the reduction factor of the recently developed fiber reinforced high strength concrete design guideline(draft). By collecting material and member test data performed for the development of the design guideline(draft), statistical characteristics of material strength and member strength analysis equations are obtained. A simul ation that appl ies the material statistical characteristics and the member anal ysis equation of the design guidel ine(draft) is performed, and the statistical characteristics of the section strength are calculated by combining the statistical characteristics of the analysis equation. Reliability analysis was performed by applying the load combination of the domestic highway bridge design code and concrete structural code, and it was confirmed that the design that applies the reduction factor for materials and members suggested in the design guideline(draft) satisfies the target reliability index.

• International Journal of Contents
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• v.3 no.3
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• pp.1-5
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• 2007

The main memory DBMS (MMDBMS) efficiently supports various database applications that require high performance since it employs main memory rather than disk as a primary storage. An index manager is an essential sub-component of a DBMS used to speed up the retrieval of objects from a large volume of a database in response to a certain search condition. Previous research efforts on indexing proposed various index structures. However, they hardly dealt with the practical issues occurred in implementing an index manager on a target DBMS. In this paper, we touch these issues and present our experiences in developing the index manager. The main issues are (1) compact representation of an index entry, (2) support of variable-length keys. (3) support of multiple-attribute keys, and (4) support of duplicated keys.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.10
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• pp.138-148
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• 1995

While Model-based Monitoring systems based on state observer theory have shown much promise in the laboratory, they have not been widely accepted by industry because, inpractice, these systems often have poor performance with respect to accuracy, band-width, reliability(false alarms), and robustness. In this paper, the linitations of the deterministic discrete-time state observer are investigated quantitatively from the machine monitoring viewpoint. The limitations in the transient and steady-state observer performance are quantified as estimation error bounds from which performance indices are selected. Each index represents the conditioning of the corresponding performance. By utilizing matrix norm theory, an unified main index is determined, that dominates all the indices. This index could from the basis for an observer design methodology that should improve the performance of model-based monitoring systems.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.25-33
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• 2016

This paper describes three-dimensional computational fluid dynamics (CFD) simulation of liquid-liquid flow and transient tracer tests in a full-scale continuous stirred-tank reactor (CSTR) used for drinking water treatment. To evaluate the effects of inlet flow rate on hydrodynamic behavior in the selected CSTR, inlet flow rate was changed from 10% to 100% of the design flow rate. From the results of CFD simulation and analysis, as the inlet flow rate increases, Modal index and ${\beta}$ value are increased. Also, Morrill index shows local minimal points in relation to the inlet flow rate, which are observed at 20% and 40% of the design flow. As inlet flow Increases more than 40%, it is shown that Morrill index re-increases to close to ideal CSTR.

• Journal of KIISE:Databases
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• v.35 no.2
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• pp.169-181
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• 2008

Because moving objects usually move on spatial networks, efficient trajectory index structures are required to achieve good retrieval performance on their trajectories. However, there has been little research on trajectory index structures for spatial networks such as FNR-tree and MON-tree. But, because FNR-tree and MON-tree are stored by the unit of the moving object's segment, they can't support the whole moving objects' trajectory. In this paper, we propose an efficient trajectory index structure, named Trajectory of Moving objects on Network Tree(TMN Tree), for moving objects. For this, we divide moving object data into spatial and temporal attribute, and preserve moving objects' trajectory. Then, we design index structure which supports not only range query but trajectory query. In addition, we divide user queries into spatio-temporal area based trajectory query, similar-trajectory query, and k-nearest neighbor query. We propose query processing algorithms to support them. Finally, we show that our trajectory index structure outperforms existing tree structures like FNR-Tree and MON-Tree.

• Journal of Distribution Science
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• v.16 no.12
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• pp.5-11
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• 2018

Purpose - We investigate the relationship between economic policy uncertainty (EPU) of the US and China and housing distribution economy in Korea using EPU indexes of two countries and the economic indicators in Korea. Research design, data, and methodology - We use the data such as the Korean housing price stability index (HPSI), housing purchase price index (HPPI), housing lease price index (HLPI), banking stock index (BSI), and consumer price index (CPI) with EPU indexes from January 1999 to December 2017. As an empirical methodology, we select the vector error correction model (VECM) due to the existence of cointegration. Result - As results of the impulse response function, the impact of the US EPU index has initially a negative response on the Korean HPSI, HPPI, and HLPI referring the housing distribution market including the economic variables, BSI, and CPI. Likewise, the impact of index in China has initially a negative response on economic indicators except the BSI in Korea. Conclusions - This study shows that the EPU index of the US has significantly negative relationships on all economic indicators in Korea. In this study, we reveal EPU of the US and China has dynamic impact on housing distribution economy returns in Korea.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.147-157
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• 2011

As a background study to apply the reliability-based resistance factors to the domestic concrete bridge design code, a comparative study is conducted for the design results and the reliability indexes obtained by adopting different resistance factor formats to yield the design strength of concrete structures. The design results which are calculated by applying the section resistance factors of the current domestic design code and the material resistance factors of Eurocode are compared for the concrete beam bridge. The reliability index is calculated by considering the uncertainties involved in material, dimension and strength equation during the design procedure to get the strength of concrete structure. Also, the sensitivity analysis is performed to figure out which design variables have great impact on the reliability index. The resistance factors of the current domestic bridge design code, AASHTO LRFD and Eurocode are applied to the bridge design for flexure and shear strength and the results show that the resistance factors of the domestic code give the largest reliability indexes. It is observed that the probabilistic distribution of the live load makes difference for the reliability index and the yield strength of reinforcing steel and the live load have great impact on the reliability of both flexural and shear strength of concrete beam through the sensitivity analysis.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.110-124
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• 2022

The purpose of this study is to develop community design evaluation factors for sustainable urban regeneration and to suggest considerations for sustainable community design by analyzing excellent community design cases. Through literature review, previous studies on the concept and core items of sustainable urban regeneration, and the concept and components of community design were considered. In addition, evaluation indicators for sustainable community design were developed in the socio-economic, physical, environmental, historical and cultural dimensions through the analysis of the linkage with the evaluation factors of community design through the analysis of previous studies. The evaluation index consists of 3 evaluation items and 9 items including social performance and participation at the social level, economic feasibility at the economic level, environmental characteristics at the physical and environmental level, accessibility, contextuality, locality at the historical and cultural level, identity, and artistry. Includes dog evaluation factors. Reliability and effectiveness are secured through the developed evaluation index and detailed description and expert verification. Exploratory factor analysis and expert interviews were conducted through the survey, and as a result of the analysis, the stability and Cronbach'α coefficients were verified, and the validity of the community design evaluation index considering sustainable urban regeneration was recognized through expert interview. The results of this study are considered meaningful in that they can provide basic data for the improvement of community design for sustainable urban regeneration in the future.