• 한국산학기술학회논문지
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• 제16권10호
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• pp.6860-6868
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• 2015

본 연구에서는 국내 도시가스 일일 수요 예측에 대한 문제를 다룬다. 정확한 일일 수요 예측은 안정적인 도시가스의 수급을 위해서 필수적인 사항으로 실제 가스 공급기관의 일상 업무에 해당한다. 본 연구에서는 수요예측 방법을 고안하기 위하여 일일 도시가스 수요 시계열에 대한 데이터 분석을 수행하였으며, 예측일 수요에 영향을 주는 주요한 요인으로 직전일 수요, 기온, 요일 등을 파악하였다. 본 연구에서는 이러한 요인들을 고려한 회귀 모형과 국내 도시가스 수요 특성에 맞는 선별적 샘플링 절차를 제안하였다. 제안 모형과 선별적 샘플링 절차로 구성된 예측 방법의 성능 검증을 위하여 실제 도시가스 수요에 대한 예측을 수행하였다. 문헌에 소개된 기존 방법과 예측 성능을 비교한 결과, 본 연구에서 제안한 방법의 평균절대백분율오차는 약 2.22%로서 개선 비율은 대략 7%에 해당한다.

• Industrial Engineering and Management Systems
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• 제13권3호
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• pp.319-329
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• 2014

Supply chain management is a subject that has an increasing importance due to the developments in the global markets and technology. In this paper, a fuzzy multi-objective linear programming model is developed for the supply chain of a company dealing with procurement, storage, filling, and distribution of liquefied petroleum gas (LPG) in Turkey. The model intends to determine the quantities of LPG to be procured, stored, filled to cylinders, and transported between the plants and demand centers for six planning periods. In this model, which aims to minimize both total costs (sum of procurement, storage, filling, and transportation costs) and total transportation distances, demand quantities of the main demand centers and decision maker's aspiration levels about objective functions are fuzzy. After comparing the results obtained from the model with those obtained by using different methods, it is concluded that the proposed method can be applied to real world problems practically and it may be used in this type of problems in order to generate an efficient solution.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.368-375
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• 2011

Along with the growing interest in greenhouse gas reduction, the effect of energy reduction from green buildings is gaining interest as well. However, green buildings may have difficulties in financing due to their high initial construction costs. With this in mind, the objective of this study is to suggest a financing model for green building projects with a governmental guarantee based on CER (Certified Emission Reduction). In other words, in the financing model, the government provides a guarantee for the increased costs of a green building project in return for CER. The suggested financing model was tested and found feasible for implementing green building projects. In addition, the model in this study is applicable to private projects because guarantee has its return. To utilize CER as a return for a financial guarantee, however, certification of CDMs (Clean Development Mechanism) for green buildings must be vitalized.

• Computers and Concrete
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• 제11권6호
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• pp.541-569
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• 2013

There is a wide variety of existing Genetic Algorithms (GA) operators and parameters in the literature. However, there is no unique technique that shows the best performance for different classes of optimization problems. Hence, the evaluation of these operators and parameters, which influence the effectiveness of the search process, must be carried out on a problem basis. This paper presents a comparison for the influence of GA operators and parameters on the performance of the damage identification problem using the finite element model updating method (FEMU). The damage is defined as reduction in bending rigidity of the finite elements of a reinforced concrete beam. A certain damage scenario is adopted and identified using different GA operators by minimizing the differences between experimental and analytical modal parameters. In this study, different selection, crossover and mutation operators are compared with each other based on the reliability, accuracy and efficiency criteria. The exploration and exploitation capabilities of different operators are evaluated. Also a comparison is carried out for the parallel and sequential GAs with different population sizes and the effect of the multiple use of some crossover operators is investigated. The results show that the roulettewheel selection technique together with real valued encoding gives the best results. It is also apparent that the Non-uniform Mutation as well as Parent Centric Normal Crossover can be confidently used in the damage identification problem. Nevertheless the parallel GAs increases both computation speed and the efficiency of the method.

• 한국컴퓨터산업학회논문지
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• 제2권10호
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• pp.1309-1316
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• 2001

애니매이션과 컴퓨터 게임에서 오늘날 주요 관심사는 캐릭터의 행동을 미리 정의된 게임 로직이나 미리 설정된 동작에 의해 제어된다. 게임 개발자들은 더 풍부하고 더 상호 보완적인인 게임을 제작하고자 하기 때문에 자주 이러한 접근은 한계에 부딪힌다. 본 논문에서는 더욱 지능적이고 강제적인 컴퓨터 게임을 만들기 위해서 유전자 알고리즘을 사용한 게임 모델을 제안한다. 학습능력에 기반 한 유전자 알고리즘의 사용은 변화와 능동적인 게임 환경을 지원하도록 연속적인 진화를 하는 캐릭터를 활용할 것이다. 임의의 실시간 게임이 제안된 시스템의 수행과 제한성을 평가하기 위해 수행되었다.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.1256-1263
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• 2022

With the advent of the Fourth Industrial Revolution, the amount of energy used in buildings has been increasing due to changes in the energy use structure caused by the massive spread of information-oriented equipment, climate change and greenhouse gas emissions. For the efficient use of energy, it is necessary to have a plan that can predict and reduce the amount of energy use according to the type of energy source and the use of buildings. To address such issues, this study presents a model embedded in a digital twin that predicts energy use in buildings. The digital twin is a system that can support a solution of urban problems through the process of simulations and analyses based on the data collected via sensors in real-time. To develop the energy use prediction model, energy-related data such as actual room use, power use and gas use were collected. Factors that significantly affect energy use were identified through a correlation analysis and multiple regression analysis based on the collected data. The proof-of-concept prototype was developed with an exhibition facility for performance evaluation and validation. The test results confirm that the error rate of the energy consumption prediction model decreases, and the prediction performance improves as the data is accumulated by comparing the error rates of the model. The energy use prediction model thus predicts future energy use and supports formulating a systematic energy management plan in consideration of characteristics of building spaces such as the purpose and the occupancy time of each room. It is suggested to collect and analyze data from other facilities in the future to develop a general-purpose energy use prediction model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.91-94
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• 2002

It is important to develop new effective technologies for increasing the interruption capacity and reducing the size of a GCB (Gas Circuit Breaker). It is not easy to test the real GCB model in practice as in theory. Therefore, a simulation tool based on a CFD (Computational Fluid Dynamics) algorithm has been developed to facilitate an optimization of the interrupter. But the choice of grid is not at all trivial in the complicated geometries like a GCB. In this paper, we have applied a CFD-CAD integration using Cartesian cut-cell method, which is one of the grid generation techniques for dealing with complex and multi-component geometries.

• 한국자동차공학회논문집
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• 제8권5호
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• pp.86-95
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• 2000

A modified spray impingement model has been developed, which is assessed against experiments for the impinging sprays on the small combustion chamber at various gas pressures. To investigate spray behaviors in the diesel combustion chamber, a transparent constant-volume chamber is made which is similar to the combustion chamber of the real diesel engine. The chamber is pressurized by N2 gas from 0 bar to 20 bar to find the effects of ambient pressures. The behaviors of spray injected into this chamber and dispersed after impingement on the cylinder wall is measured two-dimensionally using laser sheet Mie scattering method. The physical submodels have been properly modified to improve the prediction capability of original KIVA code to describe the spray behaviors after impingement on the curved cylinder wall. In terms of spray dynamics and evolution. numerical results give qualitatively good agreements with experimental data.

• 한국추진공학회지
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• 제2권3호
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• pp.90-98
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• 1998

본 연구에서 개발한 고압증발 모델을 이용하여 고압 연소장에서의 액체연료추진제의 증발 과정을 수치적으로 해석하였다. 고압상태에서 액적의 증발 특성에 중요한 영향을 미치는 실제 기체의 거동, 온도 및 압력에 따른 가변물성치의 영향, 주위기체의 용해현상을 고려하였고 일반적인 상평형 관계식을 이용하였다. 실험치와 비교하여 고압증발모델의 예측능력을 체계적으로 검증하였고 로켓엔진의 고온 고압 연소실조건에서 LOX 액적의 증발 특성을 상세하게 논의하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.890-892
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• 1996

This paper presents a method for optimal placement of series condenser in order to improve the power system transient stability using genetic algorithms(GAs). In applying GAs, this approach utilizes two kinds of strings, one is coded by a binary finite-length for the selection of lines to install series condenser, the other is coded by a real value for the determination of injected condenser capacitance. For the formulation. this paper considers multi-objective function which is the critical energy as decelerating energy in power systems and the total injected condenser capacitance. The proposed method is applied to 9-bus, 18-line, 3-machine model system to show its effectiveness in determining the locations to install series condenser and the series condenser capacitance to be injected, simultaneously.