• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.4
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• pp.263-269
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• 2010

The present study deals with the investigation about the improvement of performance of tidal stream turbine blade (HAT) with tip rake. HAT impeller has sometimes experienced noise and vibration by Tip vortex which causes even erosion and severe efficiency loss to the blade, The newly proposed tip rake impeller can make the tip vortex week compared with a normal impeller by preventing the three dimensional effect at tip region. In order to find out the optimum rake impeller, three cases have been designed and the performance of the designed rake impellers has been validated by the commercial CFD code(Fluent). The efficiency of optimized rake impeller was up to 4.6% higher than the conventional impeller. The more parametric study for high efficiency and good cavitation performance is expected to be conducted in a near future.

• Structural Engineering and Mechanics
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• v.84 no.3
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• pp.345-360
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• 2022

In this paper, the impact on seismic performance of an economical effective technique for retrofitting reinforced concrete (RC) columns using high-strength steel strips under high axial compression ratios was presented. The experimental program included a series of cyclic loading tests on one nonretrofitted control specimen and three retrofitted specimens. The effects of the axial compression ratio and spacing of the steel strips on the cyclic behavior of the specimens were studied. Based on the test results, the failure modes, hysteretic characteristics, strength and stiffness degradation, displacement ductility, and energy dissipation capacity of the specimens were analyzed in-depth. The analysis showed that the transverse confinement provided by the high-strength steel strips could effectively delay and restrain diagonal crack development and improve the failure mode, which was flexural-shear failure controlled by flexural failure with better ductility. The specimens retrofitted using high-strength steel strips showed more satisfactory seismic performance than the control specimen. The seismic performance and deformation capacity of the retrofitted RC columns increased with decreasing axial compression ratio and steel strip spacing. Based on the test results, a hysteretic model for RC columns that considers the transverse confinement of high-strength steel strips was then established. The hysteretic model showed good agreement with the experimental results, which verified the effectiveness of the proposed hysteretic model. Therefore, the aforementioned analysis can be used for the design of retrofitted RC columns.

• Steel and Composite Structures
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• v.50 no.3
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• pp.265-280
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• 2024

The collapse behavior observed in single-story beam-column assembly (SSBCA) do not accurately represent the actual overall stress characteristic of multi-story frame structure (MSFS) under column loss scenario owing to ignoring the interaction action among different stories, leading to a disconnection between the anti-collapse behaviors of "components" and "overall structures", that is, the anti-collapse performance of frame structures with two different structural scales has not yet formed a combined force. This paper conducts a numerical and theoretical study to explore the difference of the collapse behaviors of the SSBCA and MSFS, and further to reveal the internal force relationships and boundary constraints at beam ends of models SSBCA and MSFS. Based on the previous experimental tests, the corresponding refined numerical simulation models were established and verified, and comparative analysis on the resistant-collapse performance was carried out, based on the validated modeling methods with considering the actual boundary constraints, and the results illustrates that the collapse behaviors of the SSBCA and MSFS is not a simple multiple relationship. Through numerical simulation and theoretical analysis, the development laws of internal force in each story beam under different boundary constraints was clarified, and the coupling relationship between the bending moment at the most unfavorable section and axial force in the composite beam of different stories of multi story frames with weld cover-plated flange connections was obtained. In addition, considering the effect of the yield performance of adjacent columns on the anti-collapse bearing capacities of the SSBCA and MSFS during the large deformation stages, the calculation formula for the equivalent axial stiffness at the beam ends of each story were provided.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.5
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• pp.33-42
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• 2012

This study aims to establish the performance standard for natural type landscape stone GFRC. The required performance such as material performance, structural safety performance, durability performance, and landscape performance were selected through an examination of domestic and overseas performance related references and examples, and through the questionnaires obtained from 40 experts, and the verified items and performance standards were proposed. Among the required performances, the material performance(glass fiber content, air-dried gravity), structural safety performance(flexural strength, compressive strength), durability performance(crack, corrosion resistance), and landscape performance(texture, efflorescence) were selected through the questionnaires obtained from the experts. In the case of material performance and structural safety performance with the corresponding standards that existed, final performance evaluation standard was proposed by conducting a test and comparing it with the existing standard sample, and in the case of durability performance and landscape performance on which standard does not existed, they were verified by measuring directly through field examination of formative landscape items such as artificial waterfall etc. In this study, performance standard for the material on natural type landscaping rocks GFRC and items which can be evaluated after construction such as material performance, structural safety performance, durability performance, landscape performance, and so forth were proposed, however, follow up study for pro-environmental and ecological performance standard which were recently gaining force would be required through a continuous monitoring for the construction samples afterwards.

• KIEAE Journal
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• v.15 no.6
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• pp.11-18
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• 2015

Purpose: The current study analyzed trends in thermal insulation performance with aging, and condensation characteristics caused by the former. Method: Thermal insulation and condensation prevention performance of an architecture were assessed using Temperature Difference Ration Inside, or TDRi. Subjects of this quantitative analysis in thermal insulation performance change due to aging included recently constructed apartments and aged apartments older than 40 years. Time series comparison and analysis were conducted to observed changes in the thermal insulation performance and condensation characteristics. Result: Analysis showed that wall insulation performance degraded with aging regardless of fortified insulating material usage or insulating material type, which caused increased danger of condensation. In addition, when fortified insulating material was installed on the connection between the walls, insulation performance degradation was lower compared to cases in which fortified materials were not used. In all cases from 1 to 10, the rate of thermal insulation performance degradation increased after 20 years of aging.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1591-1598
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• 2009

Recently, the researches on the urban regeneration projects have been performed very actively. It is a part of the effort that solves some social and economical problems occurred by deteriorated buildings and degraded infrastructures through new urban regeneration projects or redevelopment projects. However, the urban regeneration projects show the characteristics that can not guarantee in the project performance because the projects have various and complex stakeholders related to these projects and are exposed to lots of risks due to its huge scale. This study proposed the risk performance index method to improve the efficiency of the overall performance measurement for a mega-project by extending from the traditional cost/schedule based performance measurement system. The risk performance index method proposed in this study has a similar system to the EVMS, and makes possible to perform a three dimensional integrated performance measurement in cost/schedule/risk through 18 different indexes that compose the risk performance index.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.9
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• pp.26-32
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• 2008

The conventional shared bus architecture is capable of processing only one data transaction in same time. In this paper, we propose the NAWM (No Arbitration Wild Master) bus architecture that is capable of processing several data transactions in same time. After designing the master and the slave wrappers of NAWM bus architecture about AMBA system, we confirm that most of IPs of AMBA system can be a lied without modification and the added timing delay can be neglected. from simulation we deduce that more than 50% parallel processing is possible when several masters initiate slaves in NAWM bus architecture.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1128-1133
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• 2008

Context-aware computing has been attracting the attention as an approach to alleviating the inconvenience in human-computer interactions. This paper proposes a context-aware system architecture to be implemented on an UoC (Ubiquitous system on Chip). A new proposed technology of CRS (Context Recognition Switch) and DOS (Dynamic and Optimal Standard) based on Context-awareness system architecture with pre-processor, HPSP(High Performance Signal Processor) in this paper. And proposed a new algorithm using in network topology processor shows for Ubiquitous Computing System. implementing in UoC (Ubiquitous System on Chip) base on the IEEE 802.15.4 WPAN (Wireless Personal Area Network) standard. Also, This context-aware based UoC architecture has been developed to apply to mobile intelligent robots which would support human in a context-aware manner.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.684-690
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• 2010

Most of the existing SoCs have shared bus architecture which always has a bottleneck state. The more IPs are in an SOC, the less performance it is of the SOC, Therefore, its performance is effected by the entire communication rather than CPU speed. In this paper, we propose cross-bar switch bus architecture for the reduction of the bottleneck state and the improvement of the performance. The cross-bar switch bus supports up to 8 masters and 16 slaves and parallel communication with architecture of multiple channel bus. Each slave has an arbiter which stores priority information about masters. So, it prevents only one master occupying one slave and supports efficient communication. We compared WISHBONE on-chip shared bus architecture with crossbar switch bus architecture of the SOC platform, which consists of an OpenRISC processor, a VGA/LCD controller, an AC97 controller, a debug interface, a memory interface, and the performance improved by 26.58% than the previous shared bus.

• Journal of the Ergonomics Society of Korea
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• v.32 no.2
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• pp.159-165
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• 2013

Objective: The aim of this study was to predict human performance time in finding objects on multi-display monitors using ACT-R cognitive architecture. Background: Display monitors are one of the representative interfaces for interaction between people and the system. Nowadays, the use of multi-display monitors is increasing so that it is necessary to research about the interaction between users and the system on multi-display monitors. Method: A cognitive model using ACT-R cognitive architecture was developed for the model-based evaluation on multi-display monitors. To develop the cognitive model, first, an experiment was performed to extract the latency about the where system of ACT-R. Then, a menu selection experiment was performed to develop a human performance model to find objects on multi-display monitors. The validation of the cognitive model was also carried out between the developed ACT-R model and empirical data. Results: As a result, no significant difference on performance time was found between the model and empirical data. Conclusion: The ACT-R cognitive architecture could be extended to model human behavior in the search of objects on multi-display monitors.. Application: This model can help predicting performance time for the model-based usability evaluation in the area of multi-display work environments.