• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2697-2711
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• 2023

In this study, the validity of reducing the number of gas turbine stages designed for a nitrogen Brayton cycle coupled to a sodium-cooled fast reactor was assessed. The turbine performance was evaluated through computational fluid dynamics (CFD) simulations under different off-design conditions controlled by a reduced flow rate and reduced rotational speed. Two different multistage gas turbines designed to extract almost the same specific work were selected: two- and three-stage turbines (mid-span stage loading coefficient: 1.23 and 1.0, respectively). Real gas properties were considered in the CFD simulation in accordance with the Peng-Robinson's equation of state. According to the CFD results, the off-design performance of the two-stage turbine is comparable to that of the three-stage turbine. Moreover, compared to the three-stage turbine, the two-stage turbine generates less entropy across the shock wave. The results indicate that under both design and off-design conditions, increasing the stage loading coefficient for a fewer number of turbine stages is effective in terms of performance and size. Furthermore, the Ellipse law can be used to assess off-design performance and increasing exponent of the expansion ratio term better predicts the off-design performance with a few stages (two or three).

• Journal of KIBIM
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• v.5 no.1
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• pp.35-43
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• 2015

Existing pedagogical issues of digital design including BIM have been focused not on potential of Digital Design but on skills of BIM or digital modeling tool. Kinetic facade can move or change material state to react surrounding environment conditions. It is a suitable design object for teaching principle of Performance Oriented Digital Design. Variables of movements affect multi-criteria of performances of kinetic facade, so different design approach from fixed facade design should be explored. Kinetic facade design process is proposed to study pedagogical issues of Performance Oriented Digital Design in this paper. Through Kinetic facade design process, students can understand conditions, variables, and performances of digital design.

• Smart Structures and Systems
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• v.4 no.5
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• pp.655-666
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• 2008

In the past 20 years, seismic isolation has see a variety of applications in design of structures to mitigate seismic hazard. In particular, isolation has been seen as a means of achieving enhanced seismic performance objectives, such as those for hospitals, critical emergency response facilities, mass electronic data storage centers, and similar buildings whose functionality following a major seismic event is either critical to the public welfare or the financial solvency of an organization. While achieving these enhanced performance objectives is a natural (and oftentimes requisite) application of seismic isolation, little attention has been given to the extension of current design practice to isolated buildings which may have more conventional performance objectives. The development of a rational design methodology for isolated buildings requires thorough investigation of the behavior of isolated structures subjected to seismic input of various recurrence intervals, and which are designed to remain elastic only under frequent events. This paper summarizes these investigations, and proposed a consistent probabilistic framework within which any combination of performance objectives may be met. Analytical simulations are presented, the results are summarized. The intent of this work is to allow a building owner to make informed decisions regarding tradeoffs between superstructure performance (drifts, accelerations) and isolation system performance. Within this framework, it is possible to realize the benefits of designing isolated buildings for which the design criteria allows consideration of multiple performance goals.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.198-208
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• 1998

For the development of a gas turbine engine, repetitive calculation process to determine design point and off-design performance based on basic design requirements resulted from the market survey is necessary Due attention then, must be given that design process must be carried out within the mechanical limits satisfying conservation laws of mass, work as well as speed equilibrium between the components for maximum performance. It is the purpose of the present study to deal with technical particulars during design point and off-design process of gas turbine engine performance analysis for simple cycle as well as combined cycle.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.168-178
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• 2002

The purpose of this study is to develop an optimal performance design ova concrete median barrier using the design of experiment and crash simulation which is done by Pam-Crash, one of the commercial crash simulation software. A formula of characteristic value was suggested to obtain an optimal performance design considering all of von Mises stress, volume and acceleration at center of gravity of a heavy truck. An optimal design of a concrete median barrier was obtained by the analysis of variance based on design of experiment and crash simulation. A crash simulation with the optimal design was accomplished in order to verify the suitability of the suggested formula and the proper application of the design of experiment. The obtained optimal design was satisfied for a domestic design regulation of a concrete median barrier.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.5
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• pp.553-559
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• 1999

The robust control problem of the linear systems with uncertainty is classified as the robust stability problem guaranteeing the stability and the robust performance problem guaranteeing the disired performance. In this paper, we considered the robust performance analysis problem, which find the upper buund of the quadratic performance of the uncertain linear system, and the robust guaranteed performance controller design problem which design a controller guaranteeing the desired quadratic performance. At first, we treated the analysis problem and presented the two results; one is dependent on the performance of the nominal system and another is independent on this. And we treated the design method guaranteeing the desired performance for the uncertain linear systems, Finally, we show the usefulness of our results by numerical examples.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.223-230
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• 2002

Earthquake resistance design has been developed many countries like Japan, USA, Mexico, New Zealand etc., which countries have experienced many earthquakes. Nowadays, earthquake resistance design has come into worldwide use. In Korea, the seismic design regulations have been established since 1988 in order to minimize the economic losses. Recently performance based design method has been adopted as a new Earthquake resistance design method. These regulations, however, are targeted for newly constructed buildings, In Korea, there are no regulations for existing buildings that built before 1988. On the other hand, in Japan and USA, the seismic performance evaluation is coded. In Japan, the evaluation index which can measure seismic performance has been made. So, we need to prepare the regulations that evaluate the seismic performance, furthermore proper retrofitting design guideline needs to be proposed when remodeling old buildings. In this research, various seismic performance evaluation methods which are being used in Japan and USA are reviewed in order to establish seismic performance evaluation index for those existing old structures in Korea.

• Wind and Structures
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• v.32 no.4
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• pp.283-292
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• 2021

Performance-based seismic design (PBSD) is currently used for retrofitting of older buildings and the design of new buildings. Whereas, application of performance-based design for wind load is still under development. The tendency has been in the codes to increase wind hazard based on recent recorded events. Since tall buildings are highly susceptible to wind load, necessity for developing a framework for performance-based wind design (PBWD) has intensified. Only a few guidelines such as ASCE (2019) provide information on using PBWD as an alternative for code prescriptive wind design. Though wind hazards, performance objectives, analysis techniques, and acceptance criteria are explained, no recommendations are provided for several aspects like how to select a proper level of wind hazard for each target performance criterion. This paper is an attempt to explain current design philosophy for wind and seismic loads and inherent connection between the components of PBSD for development of a framework for PBWD of tall buildings. Recognizing this connection, a framework for PBWD based on limits set for serviceability and strength is also proposed. Also, the potential for carrying out PBWD in line with ASCE 7-16 is investigated and proposed in this paper.

• Earthquakes and Structures
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• v.15 no.3
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• pp.253-261
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• 2018

This article details a bridge-specific fragility method developed to enhance the seismic design and resilience of bridges. Current seismic design processes provide guidance for the design of a bridge that will not collapse during a design hazard event. However, they do not provide performance information of the bridge at different hazard levels or due to design changes. Therefore, there is a need for a supplement to this design process that will provide statistical information on the performance of a bridge, beyond traditional emphases on collapse prevention. This article proposes a bridge-specific parameterized fragility method to enable efficient estimation of various levels of damage probability for alternative bridge design parameters. A multi-parameter demand model is developed to incorporate bridge design details directly in the fragility estimation. Monte Carlo simulation and Logistic regression are used to determine the fragility of the bridge or bridge component. The resulting parameterized fragility model offers a basis for a bridge-specific design tool to explore the influence of design parameter variation on the expected performance of a bridge. When used as part of the design process, these tools can help to transform a prescriptive approach into a more performance-based approach, efficiently providing probabilistic performance information about a new bridge design. An example of the method and resulting fragility estimation is presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.659-662
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• 2009

In this paper described are the performance design guidelines of writing the items of foundation structures for designers. To accept the new performance code instead of existing design code in the construction market, performance design focuses on requirements to guidelines of foundation structure.