• Journal of the Korea Society of Computer and Information
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• v.14 no.12
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• pp.9-16
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• 2009

Energy consumption as well as performance should be considered when designing up-to-date multicore processors. In this paper, we propose new design technique to reduce the energy consumption in the instruction cache for multicore processors by using modified filter cache. The filter cache has been recognized as one of the most energy-efficient design techniques for singlecore processors. The energy consumed in the instruction cache accounts for a significant portion of total processor energy consumption. Therefore, energy-aware instruction cache design techniques are essential to reduce the energy consumption in a multicore processor. The proposed technique reduces the energy consumption in the instruction cache for multicore processors by reducing the number of accesses to the level-1 instruction cache. We evaluate the proposed design using a simulation infrastructure based on SimpleScalar and CACTI. Simulation results show that the proposed architecture reduces the energy consumption in the instruction cache for multicore processors by up to 3.4% compared to the conventional filter cache architecture. Moreover, the proposed architecture shows better performance over the conventional filter cache architecture.

• Nuclear Engineering and Technology
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• v.29 no.1
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• pp.15-24
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• 1997

The design and evaluation of a digital U-tube steam generator level controller of nuclear power plants, which uses model-based compensators to offset the inverse response behavior of water level, is described. Included is a review of steam generator level dynamics, a simulation model that replicates the effects of feedwater and steam flowrate as well as temperature on steam generator level, the design of both the compensators and the overall controller, and the results of simulation studies in which the performances of this model-based controller and existing analog ones were compared. The proposed digital steam generator level controller is stable and its use significantly improves the controllability of steam generator level.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.2
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• pp.1-9
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• 2019

In a ground-source heat pump (GSHP) system, a vertical ground heat exchanger (GHE) is widely accepted due to a higher thermal performance. In the vertical GHE, grout (also called grouting material) plays an important role in the heat transfer performance and the initial installation cost of the GHE. Bentonite-based grout has been used in practice because of its high swelling potential and low hydraulic conductivity. This study evaluated the thermo-physical properties of the bentonite-based grouts through lab-scale measurements. In addition, we conducted performance simulation to analyze the effect of mixed ratio of grouts on the design length and thermal performance of the vertical GHE. The simulation results show that thermally-enhanced grouts improve the heat transfer performance of the vertical GHE and thus reduce the design length of GHE pipe.

• Journal of the Korean Institute of Educational Facilities
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• v.26 no.4
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• pp.27-34
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• 2019

Recently the architectural paradigm have been changing into eco-friendly architecture as an sustainable architecture. This social background encourages the development of various methods of building applicable for eco-friendly buildings in architectural design. Among them, passive architecture is an design approach for eco-friendly design that contrasts with technology-based methods through MEP for renewable energy. This study researches the Passive Architectural Design methodology with two points of view; Passive Architectural Design Techniques as a guideline, which defines the elements to consider for passive architecture, and the project of Sejong Municipal Public Library as a case, which is to analysis the architectural design process. The purpose of this study is to propose an eco-friendly public building based on the methodology which is suitable for passive architectural design. Finally, this study suggests that the eco-friendly public building design for passive architecture should consider from the early step of design process, such as concept and building form etc. What is important for the passive architecture is not how much building can produce the natural energy but how less building consumes it to maintain.

• Steel and Composite Structures
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• v.49 no.4
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• pp.393-405
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• 2023

In this paper, the energy absorption capability of a novel cruciform composite lattice structure was evaluated through the simulation of compression tests. For this purpose, several test samples of Polylactic acid cellular reinforced with continuous glass fibers were prepared for compression testing using the additive manufacturing method of material extrusion. Using a conventional path design for material extrusion, multiple debonding is probable to be occurred at the joint regions of adjacent cells. Therefore, an innovative printing path design was proposed for the cruciform lattice structure. Afterwards, quasistatic compression tests were performed to evaluate the energy absorption behaviour of this structure. A finite element model based on local material property degradation was then developed to verify the experimental test and extend the virtual test method. Accordingly, different combinations of unit cells' dimensions using the design of the experiment were numerically proposed to obtain the optimal configuration in terms of the total absorbed energy. Having brilliant energy absorption properties, the studied cruciform lattice with its optimized unit cell dimensions can be used as an energy absorber in crashworthiness applications. Finally, a cellular structure will be suitable with optimal behavior in crush load efficiency and high energy absorption.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1949-1954
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• 2005

One of control methods for underactuated manipulators is known as a switching control which selects a partially-stable controller using a prespecified switching rule. A switching computed torque control with a fuzzy energy region method was proposed. In this approach, some partly stable controllers are designed by the computed torque method, and a switching rule is based on fuzzy energy regions. Design parameters related to boundary curves of fuzzy energy regions are optimized offline by a genetic algorithm (GA). In this paper, we discuss on parameters obtained by GA. The effectiveness of the switching fuzzy energy method is demonstrated with some simulations.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.14-24
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• 2011

In this paper, design optimization for mixed-flow pump impellers and diffusers has been studied using a commercial computational fluid dynamics (CFD) code and DOE (design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser. Geometric design variables were defined by the vane plane development, which indicates the blade-angle distributions and length of the impeller and diffusers. The vane plane development was controlled using the blade-angle in a fixed meridional shape. First, the design optimization of the defined impeller geometric variables was achieved, and then the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Next, design optimizations of the defined diffuser shape variables were performed. The importance of the geometric design variables was analyzed using $2^k$ factorial designs, and the design optimization of the geometric variables was determined using the response surface method (RSM). The objective functions were defined as the total head and the total efficiency at the design flow rate. Based on the comparison of CFD results between the optimized pump and base design models, the reason for the performance improvement was discussed.

• Journal of Wind Energy
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• v.5 no.1
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• pp.22-32
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• 2014

The structural design of a wind turbine must show the verification of the structural integrity of all load-carrying components. Also, design load calculations shall be performed using appropriate and accurate methods. In this study, advanced numerical approach for the calculation of design loads based on unsteady computational fluid dynamics (CFD) is presented considering extreme design load conditions such as the extreme coherent gust (ECG) and the 50 year extreme operating gust (EOG). Unsteady aerodynamic loads are calculated based on Reynolds average Navier-Stokes (RANS) equations with shear-stress transport k-ω(SST k-ω) turbulent model. A full three-dimensional 5 MW offshore wind-turbine model with rotating blades, hub, nacelle, and tower configuration is practically considered and its aerodynamic interference effect among blades, nacelle, and tower is also accurately considered herein. Calculated blade loads based on unsteady CFD method with respect to blade azimuth angle are compared with those by NREL FAST code and physically investigated in detail.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.1
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• pp.29-37
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• 2017

Hospitals contribute to energy consumption and have a negative environmental impact. This study aims to find how meaningful energy performance, reflecting good energy management and design, can be planned for hospital buildings, a category encompassing complex buildings with different setups and large differences between them. Energy-consumption characteristics were surveyed throughout Korea to establish statistical energy models. Findings confirm that different hospital departments have hugely different energy-demand profiles. Energy efficiency and energy-saving potentials on HVAC systems are presented. The energy performance analysis can be applied to a wide range of problems in energy-system design and planning, including simulations and optimizations of community energy systems.

• Structural Engineering and Mechanics
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• v.44 no.5
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• pp.611-631
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• 2012

The passive energy dissipation technology has been proven to be reliable and robust for recent practical applications. Various dampers or energy dissipation devices have been widely used in building structures for enhancing their performances during earthquakes, windstorm and other severe loading scenarios. This paper presents a simplified seismic design procedure for retrofitting earthquake-damaged frames with viscous dampers. With the scheme of designing the main frame and the supplemental viscous dampers respectively, the seismic analysis model of damped structure with viscous dampers and braces was studied. The specific analysis process was described and approach to parameter design of energy dissipation components was also proposed. The expected damping forces for damped frame were first obtained based on storey shear forces; and then they were optimized to meet different storey drift requirements. A retrofit project of a RC frame school building damaged in the 2008 Wenchuan earthquake was introduced as a case study. This building was retrofitted by using viscous dampers designed through the simplified design procedure proposed in this paper. Based on the case study, it is concluded that this simplified design procedure can be effectively used to make seismic retrofit design of earthquake-damaged RC frames with viscous dampers, so as to achieve structural performance objectives under different earthquake risk levels.