• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4412-4421
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• 2022

The pressure measurement in the high-temperature liquid metal system, such as Sodium-cooled Fast Reactor(SFR), is important and yet it is very challenging due to its nature. The measuring pressure is relatively at low range and the applied temperature varies in wide range. Moreover, the pressure transfer material in impulse line needs to considered the high temperature condition. The conventional diaphragm-based approach cannot be used for it is impossible to remove the effect of thermal expansion. In this paper, the Fiber Bragg Grating(FBG) sensor-based pressure measuring concept is suggested that it is free of problems induced by the thermal expansion. To verify this concept, a prototype was fabricated and tested in an appropriate conditions. The uncertainty analysis result of the experiment is also included. The final result of this study clearly showed that the FBG-based pressure transmitter system is applicable to the extreme environment, such as SFR and any other high-temperature liquid metal system and the measurement uncertainty is within reasonable range.

• Smart Structures and Systems
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• 제26권6호
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• pp.693-701
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• 2020

The conventional Kalman Filter (KF) provides a promising way for structural state estimation. However, the physical parameters of structural systems or models should be available for the estimation. Moreover, it is not applicable when the loadings applied to the structures are unknown. To circumvent the aforementioned limitations, a two-stage KF with unknown input approach is proposed for the simultaneous identification of structural parameters and unknown loadings. In stage 1, a modified observation equation is employed. The structural state vector is estimated by KF on the basis of structural parameters identified at the previous time-step. Then, the unknown input is identified by Least Squares Estimation (LSE). In stage 2, based on the concept of sensitivity matrix, the structural parameters are updated at the current time-step by using the estimated structural states obtained from stage 1. The effectiveness of the proposed approach is numerically validated via a five-story shearing model under random and earthquake excitations. Shaking table tests on a five-story structure are also employed to demonstrate the performance of the proposed approach. It is demonstrated from numerical and experimental results that the proposed approach can be used for the identification of parameters of structure and the external force applied to it with acceptable accuracy.

• Advances in Energy Research
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• 제8권3호
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• pp.145-153
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• 2022

Recent concerns about rising fuel prices and greenhouse gas emissions have focused attention on alternative energy sources, particularly in the transport sector. Transportation consumes 40% of overall fuel usage. As a result, a growing majority of researches on Electric Vehicles (EVs) and their Energy Management Systems (EMS) have been done. In order to enhance the performance and to meet the needs of drivers, more information regarding the EMS is needed. A new Energy Management System is proposed using a FOPID controller. To put the concept into practice, state equations are utilised. The fifth-order state-space model under study is a linked model with several inputs and outputs and the transfer matrices are calculated for decoupling the system. Utilizing these transfer matrices to decouple the system and FOPID controller is used to tune the system. The tuned parameters are minimized using a Particle Swarm Optimization (PSO) approach with Integral Time Absolute Error (ITAE) as the goal. When the suggested FOPID system's results are compared to those of PID-controlled systems, a sizable improvement is observed, which is explained by the results.

• 자원ㆍ환경경제연구
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• 제9권5호
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• pp.811-827
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• 2000

Since improved thermal efficiency reduces capacity requirements and energy costs, electricity producers often treat thermal efficiency as a measure of management or economic performance. The conventional measure of the thermal efficiency of a fossil-fuel generation system is the ratio of total electricity generation to the simple sum of energy inputs. As a refined approach, we present a novel thermal efficiency measure using the concept of the Divisia index number. Application of this approach to the Korean power sector shows improvement of thermal efficiency of 1.1% per year during 1970-1998. This is higher than the 0.9% improvement per year given by the conventional method. The difference is attributable to the effect of fuel substitution. In the Divisia decomposition context, we also show the limitations of the popular $T{\ddot{o}}rnqvist$ index formula and the superiority of the Sato-Vartia formula.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.669-675
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• 2009

As the use of new and renewable energy is one of the ways by which the exhaustion of fossil fuels and the other existing environmental problems can be addressed, a policy of spreading information regarding it and of conducting R&D related to it is currently being implemented in advanced countries. In the construction field, the concept of "green building" was born, and the application of this concept has increased, with the end in view of achieving energy savings, resource savings, and recycling, and of conserving the natural environment. In this context, the government of Korea amended the "Law on the Development, Use, and Promotion of New and Recycled Energy" in 2004, which contains 11 provisions related to new and renewable energy and their sources, including solar and geothermal energy as well as sunlight, water, rainfall, and organisms. Since solar-energy should be used instead of fossil fuels by converting sunlight directly into electricity, many researches on this subject are in progress. There are few researches, however, employing the economic approach to the subject. Thus, in this study, an economic assessment of the solar-energy system was conducted using both life cycle cost (LCC) analysis and sensitivity analysis. The results of the LCC analysis show that the solar-energy system will become economically better than the fossil fuel system after 16 years, although the initial construction cost of the solar-energy system is higher than that of the fossil fuel system. The results of this study are expected to be used in selecting an eco-friendly and economical solar-energy system when the construction of a green building is planned.

• 한국경영과학회지
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• 제13권1호
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• pp.51-64
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• 1988

A new approach to the logical design of 4NF database shceme, which can be easily automated, is proposed. The main features of the approach are : introduction of a single attribute right hand side, extension of the concept of independent relations, semantic analysis, and adaoption of dependency matrix. The underlying viewpoints of functional relationships of the approach are different from Fagin's in that we distinguish functional and multivalued dependency in terms of cardinality. An algorithm for automatic generation of fourth normal form is presented and implemented.

• Structural Engineering and Mechanics
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• 제10권4호
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• pp.405-426
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• 2000

Two approximate methods based on mechanism analysis suitable for seismic assessment/design of structural concrete are reviewed. The methods involve use of equal energy concept or equal displacement concept along with appropriate patterns of inelastic deformations to relate structure's maximum lateral displacement to member and plastic deformations. One of these methods (Clough's method), defined here as a ductility-based approach, is examined in detail and a modification for its improvement is suggested. The modification is based on estimation of maximum inelastic displacement using inelastic design response spectra (IDRS) as an alternative to using equal energy concept. The IDRS for demand displacement ductilities are developed for a single degree of freedom model subjected to several accelerograms as functions of response modification factor (R), damping ratios, and strain hardening. The suggested revised methodology involves estimation of R as the ratio of elastic strength demand to code level demand, and determination of design base shear using $R_{design}{\leq}R$ and maximum displacement, determination of plastic displacement using IDRS and subsequent local plastic deformations. The methodology is demonstrated for the case of a 10-story precast wall panel building.

• 한국가구학회지
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• 제12권2호
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• pp.91-103
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• 2001

Modern Art Furniture has been represented new idea and energy for futuristic furniture design by interacting and confronting with 3 points of view, which are; the idea and emotion of art, the form and concept of design, and the technique and materials of craft. Besides, meanings of modern Art Furniture are also can be described as followed. First, offend of concept of furniture design area to art, second, help to raise the social status of people by making art to be popularized, third, present a new direction of futuristic furniture design culture. Art Furniture design area, which has been trying to make a constant approach to human consideration and sensibility, leads new furniture design culture as an independent art genre in this 21st Century.

• 한국실내디자인학회논문집
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• 제21권4호
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• pp.31-39
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• 2012

Ecosystem and environment have been a serious challenge facing the modern society. It's been the new paradigm from ecological view of the world and the alternative based on Orientalism. From the Oriental standpoint, ecological aesthetics and sustainable architecture are no longer new, which then servers the background of this study. The nature and the space, the life where the human is harmonized and integrated and the wish to make the balance through that life are the basic philosophy which the Orientalism has pursued. Based on such a basic concept, the study is intended to review the connectivity, expression approach and the features in Korean traditional residential space based on previous studies on ecological aesthetics and sustainable architecture. Such attempt is meaningful in seeking the possibility of presenting the new frame as well as forming the various views to the traditional space and spatial recognition. The nature was categorized into tangible element and intangible element and also direct approach and indirect approach before evaluating the characteristics. Sustainable architecture is not the concept to simply maintain or sustain the environment, but plays more important role in economical aspect. Traditional space accommodates the nature and circulation principle and the circulation in the nature controls the energy and enhances the efficiency, playing significant role. The nature itself serves the alternative energy and has the aesthetic element in such a way of concealing itself. This study is intended to analyze the Byulseo Jeongwon which formed many relations with the nature and the residential space, thereby identifying the expression characteristics of eco-aesthetic sustainable architect. This study offers the answers with regard to the coexistence of the expression characteristics of sustainable architecture with the nature, space and the human from eco aesthetic viewpoint as well as the solution in dealing with the ecological and environmental challenges. Furthermore, it suggested the possibility that the traditional space would possibly be succeedable in new and creative way and sought the way for coexistence among the nature, space and human and eco aesthetics, and finally paved the pivotal foundation as the sustainable design alternative in future.

• 설비공학논문집
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• 제16권1호
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• pp.91-100
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• 2004

Energy efficiency evaluation method for a multi-type air conditioning system still has not been developed. In this study, analysis on capacity range and evaluating method of standards for air conditioners was conducted with world-wide Standards. It is not a proper approach to use the standards for residential air conditioner to multi type air conditioners. Some difficulties and problems are commented in this study with overview of the standards. Through the analytic research, an evaluating method for multi type air conditioner was suggested with Integrated Part Load Value (IPLV). The suggested concept for evaluating energy efficiency during part load condition considers building load pattern and operating hours of the system at different locations. Load was weighted in IPLV to consider not only the concept of occurrence of outdoor temperature such as bin method but also operation hours of the system. An experiment about the IPLV was conducted with variable air volume ducted type air conditioning system and multi-type system through modified code tester to give a glance at quantitative value of the IPLV.