• Korean Journal of Construction Engineering and Management
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• v.10 no.4
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• pp.101-110
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• 2009

The current virtual reality(VR) simulation functions in construction project are focused on the construction phase. This study attempts to extend the application of VR functions to the design phase. This study suggests various VR functions such as earthwork simulation by road alignment, alternative route selection simulation, structure type selection simulation and underground structure visualization simulation. These functions can visualize road route and earthwork condition and select an optimal design route by simulating virtual placement of alternative route. This study configures systematic methodology for suggested VR simulation functions and develops VR system by the functions. Finally this study suggests an improved design process of road construction project by using the developed VR functions

• Journal of Environmental Science International
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• v.16 no.5
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• pp.649-655
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• 2007

This study was focused on estimating instream flow, and its optimal alternative for securing the required total amount of instream flow was also researched in order to restore ecosystems and riverine aesthetics of the Mugeo Stream. the first tributary of the Taewha River flowing through the center of Ulsan. In this study the hydraulic and hydrologic conditions and water quality were investigated at specific channel reaches and representative stations of the Mugeo Stream to determine a proper estimate of instream flow. And riverine functions, such as the minimum flow, water duality conservation, fish habitat, and recreation, were considered to restore the environmental functions of the stream, As a result, the total amount of $11,500m^3/day$ was set as the target instream flow for the Mugeo Stream. It was chosen as the optimal alternative for securing the total external supply of $10,000m^3/day$ which have to be transfered from the riverbed flow diverted through the Taewha Main river at upstream of Samho bridge. The water duality throughout the Mugeo Stream channels will be improved considerably to 3-4 mg/l of BOD standard if the target instream flow is supplied and sewage is intercepted by the sanitary sewage system.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.10a
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• pp.3-8
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• 1998

The present work proposes the potential fuzzy framework, based on fuzzy set theory, for supporting decision-making problems, especially, selection problems of a best design in the area of nuclear energy system. The framework proposed is composed of the hierarchical structure module, the assignment module, the fuzzification module, and the defuzzification module. In the structure module, the relationship among decision objectives, decision criteria, decision sub-criteria, and decision alternatives is hierarchically structured. In the assignment module, linguistic or rank scoring approach can be used to assign subjective and/or vague values to the decision analyst's judgment on decision variables. In the fuzzification module, fuzzy numbers are assigned to these values of decision variables. Using fuzzy arithmetic operations, for each alternative, fuzzy preference index as a fuzzy synthesis measure is obtained. In the defuzzification module, using one of methods ranking fuzzy numbers, these indices are defuzzified to overall utility values as a cardinality measure determining final scores. According these values, alternatives of interest are ranked and an optimal alternative is chosen. To illustrate the applicability of the framework proposed to selection problem, as a case example, the best option choice of four design options under five decision criteria for primary containment wall thickening around large penetrations in an advanced nuclear energy system is studied.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.10
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• pp.950-961
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• 2000

The objective of this study is to develop optimal alternative selection model for renewing building equipments system. Cost Breakdown Structure of LCC in HVAC systems are deduced from resonable data and factors. As for Cost Breakdown Structure of LCC in HVAC system, pertinent level, title, CBS number, and block number are determined efficiently. Especially, in addition to current cost factor, it is possible to make Cost Breakdown Structure using present worth method more clear. A model of POWER LCC ver 1.0 used to analyze primary cooling system, heating system, and air conditioning system are POWER LCC ver 1.0_/sub SYSTEM/ : C1+ C2- C3+ C4+ C5+ C6+ C7±C8+ C9- C10/sub -1/+ C10/sub -2/+ C10/sub -3/, and is implemented with consideration of Cost Breakdown Structure and their summation using present-worth method. It is programmed with one of scientific languages, MATLAB 5.3.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.489-494
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• 2011

In this paper, a method is proposed to evaluate a number of alternatives for light-weight rolling stock recommended from experts in rolling stock and to decide an optimal alternative. At first, many customer needs from various fields in railroad are drawn and weights of customer needs are decided by AHP. Secondly, technical requirements that should be real specifications for light-weight rolling stock are set and weights of technical requirements are decided by QFD. Finally, we evaluate some proposed alternatives and conclude an optimal alternative of light-weight rolling stock with TOPSIS.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.2051-2057
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• 2008

This paper is a feasibility study on the calculation of operating cost in regards to the overall operation following the completion of a number of LRT lines currently in progress. Owing to the absence of operating experience in driveless LRT system at home, the difficulties lie in the assumption of the optimal operating budget applying domestic real situation. Nevertheless, with 34 years of accumulated operating experience in heavy rail transit system, Seoul Metro, the nation's biggest urban rail transit operator, performs O&M consultancy services for several on-going projects along with every effort to acquire know-how where the appropriateness of the cost estimation as a required deliverable is reviewed and a more efficient way is provided. The main focus of this study is to seek a method to calculate the optimal amount of operating expenses as well as a cost-effective alternative for possible weaknesses from the standpoint of the operator. The body of this paper discusses the five issues such as personnel cost, overhead, maintenance cost, additional purchase price, alternative investment fee from a more macroscopic point of view, and the conclusion deals with the adequacy of the reason for selection of institutions with various operating know-how.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.2
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• pp.96-105
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• 2001

R410a which is one of HFC refrigerants is being considered to be a promising replacement for R22 widely used in domestic air conditioners. The rolling piston type rotary compressors for R410a have lower energy efficiency than those for R22 because of the high pressure difference between a suction chamber and a discharge chamber in the compression mechanism. in addition, the re-expansion gas loss of the rotary compressor for R410a which occurs a ta clearance volume in a discharge port becomes larger than that for R22 due to high density of R410a refrigerant. Therefore, Pressure-Volume analyses for various design parameters of a discharge system were carried out to improve efficiency of a R410a rotary compressor. The results such as performance dta, over-compression loss, and re-expansion loss were acquired by P-V analyses and analyzed quantitatively. As a conclusion, the optimal specifications of several design parameters of a discharge system were obtained by analyzing P-V diagrams.

• Computers and Concrete
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• v.30 no.2
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• pp.127-141
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• 2022

In this paper, a numerical procedure is proposed for achieving the minimum cost design of reinforced concrete polygonal column cross-sections under compression and biaxial bending. A methodology is developed to integrate the metaheuristic algorithm Quantum Particle Swarm Optimization (QPSO) with an algorithm for the evaluation of the strength of reinforced concrete cross-sections under combined axial load and biaxial bending, according to the design criteria of Brazilian Standard ABNT NBR 6118:2014. The objective function formulation takes into account the costs of concrete, reinforcement, and formwork. The cross-section dimensions, the number and diameter of rebar and the concrete strength are taken as discrete design variables. This methodology is applied to polygonal cross-sections, such as rectangular sections, rectangular hollow sections, and L-shaped cross-sections. To evaluate the efficiency of the methodology, the optimal solutions obtained were compared to results reported by other authors using conventional methods or alternative optimization techniques. An additional study investigates the effect on final costs for an alternative parametrization of rebar positioning on the cross-section. The proposed optimization method proved to be efficient in the search for optimal solutions, presenting consistent results that confirm the importance of using optimization techniques in the design of reinforced concrete structures.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.9
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• pp.481-486
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• 2004

In operation of distribution system, $DG_s$ Distributed Generations) are installed as an alternative of extension and establishment of substations and transmission and distribution lines according to increasing power demand. In operation planning of $DG_s$, determining optimal capacity and allocation gets economical pro(it and improves power reliability. This paper proposes determining a optimal number, size and allocation of $DG_s$ needed to minimize operation cost of distribution system. Capacity of $DG_s$ (or economical operation of distribution system estimated by the load growth and line capacity during operation planning duration, DG allocations are determined to minimize total cost with power buying cost. operation cost of DG, loss cost and outage cost using GA(Genetic Algorithm).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.605-610
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• 2002

Eigenvalues are taken as performance criteria for structural damping design using viscoelastic material. Given material properties, optimal distribution of damping material is sought based on eigenvalue sensitivity. For eigenanalysis of frequency dependent viscoelastic material treated structures, Golla-Mushes-McTavish (GHM) model is used and some dominant modes are chosen for consideration. To avoid the intensity of computation caused by increased problem size, an alternative approximate method is proposed which uses elastic modes and can be applied under small damping assumption. A cantilever beam treated with unconstrained viscoelastic layer is tested and optimal distribution of thickness of the layer is illustrated. Partial coverage configurations are compared with the one-sided full coverage case.