• 한국건설순환자원학회논문집
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• 제7권1호
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• pp.8-15
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• 2019

콘크리트 구조물이 극심한 열화 환경에 노출되는 경우 열화현상이 발생하게 되는데, 대표적인 열화 현상으로는 염해에 의한 철근부식이 있다. 본 연구에서는 3가지 수준의 물-결합재 비(0.37, 0.42, 0.47) 및 2가지 수준의 플라이애시 치환율(0%, 30%)을 고려하여 재령 2년 콘크리트 시편을 대상으로 염해 저항 성능을 평가하였다. Tang's method에 준하여 촉진 염화물 확산계수를, ASTM C 1202에 준하여 통과 전하량을, KS F 2405에 준하여 압축강도를 평가하였다. 또한 기존의 제안식들과 촉진 염화물 확산계수 결과를 활용하여 각 배합의 시간의존성 확산 특성을 분석하였다. 플라이애시 혼입 배합은 OPC 배합 대비 뛰어난 내구성능을 나타내는데, 통과 전하량 평가기준에 따르면 재령 49일부터 "Moderate" 등급 이하에 포함되는 반면 OPC 배합은 재령 1년에서야 모든 물-결합재 비에서 "Moderate" 등급 이하에 포함되었다. 각 배합의 시간의존성지수를 도출한 결과 모든 배합에서 물-결합 재비가 증가함에 따라 시간의존성지수가 감소하는 경향을 나타내었다. 또한, 플라이애시 혼입 배합에서 OPC 배합 대비 1.57배~2.74배의 시간의존성지수가 평가되었다. 이는 시간의존성지수가 확산계수가 감소하는 기울기를 나타내기 때문이며, 플라이애시의 포졸란 반응에 의해 FA 배합에서 OPC 배합 대비 높은 시간의존성지수를 나타내었다.

• 한국기계가공학회지
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• 제11권4호
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• pp.55-61
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• 2012

Very important content in performance evaluation of machine tool is positioning accuracy and repeatability precision measurements of feed mechanism. A study analyses the measurement method and uncertainty factors by ISO-based test method. Reliable results can't be derived without the notion of measurement uncertainty. The reason is that the measured value includes a lot of uncertain factors. Finding the factor that affects the measurement of parameter is important for estimation of measurement precision. In this paper, the evaluation of uncertainty analysis about positioning accuracy and repeatability precision measurements of high precision feed mechanism is presented to evaluate the important factors of uncertainty.

• 품질경영학회지
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• 제36권4호
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• pp.19-28
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• 2008

The purpose of this study is to search for the quality characteristics for evaluation of the information system. The quality characteristics are an important factor for selection, implementation and maintenance of the information system of the company. Of course in the end, the quality of the information system in a company is directly related with the business performance of the company. This paper is a study of a model with four independent variables, a parameter variable, and a total of 15 hypotheses, investigated by a questionnaire method. It conducted the model analysis of structural equation to use statistical package for questionnaire analysis.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 춘계학술대회논문집
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• pp.3-8
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• 2003

A Simulation S/W is developed to evaluate performances of MLS (Microwave Landing System) and IBLS(Integrated Beacon Landing System) in precision auto-landing. For this study classical PID and optimal LQG controllers are developed as well as mathematical models of MLS and IBLS. Ship-landing condition is also considered by assuming sinusoidal movement of the ship in the pitch direction. The simulated aircraft is F-16 in the study of precision auto-landing. For the integrated simulation environment GUI windows are designed for input of parameter values necessary for simulation, such as vehicle performance and environmental data. For validation and verification of models various comparison graphs of simulation outputs are comprised in the GUI design as well as 3D visual simulation of vehicle dynamics.

• 대한기계학회논문집B
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• 제28권3호
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• pp.296-303
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• 2004

The heat and flow characteristics in a single-phase parallel-flow heat exchanger was examined numerically to obtain its optimal shape. A response surface method was introduced to approximately predict its performance with respect to the design parameters over the design domain. The inflow/outflow angle of the working fluid, the location of inlet/outlet, the protruding height of flat tube and the height of header were chosen as a design parameter The evaluation of the relative importance of the design parameters was performed based on a sensitivity analysis. An efficiency index was used as an evaluation characteristics value to simultaneously consider both the heat transfer and the pressure drop. The efficiency index of the optimum model, compared to that of the base model, was increased by 9.3%.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 춘계학술대회
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• pp.91-97
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• 2002

In this thesis presents line balancing problems of two-sided and mixed model assembly line widely used in practical fields using genetic algorithm for reducing throughput time, cost of tools and fixtures and improving flexibility of assembly lines. Two-sided and mixed model assembly line is a special type of production line where variety of product similar in product characteristics are assembled in both sides. This thesis proposes the genetic algorithm adequate to each step in tow-sided and mixed model assembly line with suitable presentation, individual, evaluation function, selection and genetic parameter. To confirm proposed genetic algorithm, we apply to increase the number of tasks in case study. And for evaluation the performance of proposed genetic algorithm, we compare to existing algorithm of one-sided and mixed model assembly line. The results show that the algorithm is outstanding in the problems with a larger number of stations or larger number of tasks.

• 대한안전경영과학회지
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• 제4권2호
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• pp.83-101
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• 2002

In this thesis presents line balancing problems of two-sided and mixed model assembly line widely used in practical fields using genetic algorithm for reducing throughput time, cost of tools and fixtures and improving flexibility of assembly lines. Two-sided and mixed model assembly line is a special type of production line where variety of product similar in product characteristics are assembled in both sides. This thesis proposes the genetic algorithm adequate to each step in tow-sided and mixed model assembly line with suitable presentation, individual, evaluation function, selection and genetic parameter. To confirm proposed genetic algorithm, we apply to increase the number of tasks in case study. And for evaluation the performance of proposed genetic algorithm, we compare to existing algorithm of one-sided and mixed model assembly line. The results show that the algorithm is outstanding in the problems with a larger number of stations or larger number of tasks.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 춘계학술대회 논문집
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• pp.251-252
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• 2003

Most particles capable of reaching the thoracic region of humans are in the size range below 10$\mu$m in diameter. Particles with a diameter smaller than 2.5 $\mu$m are deposited in large amounts in the alveolar region during mouth inhalation. The hazard caused by fine particles depends on their chemical composition and the site within the human respiratory system where they are deposited(Hinds, 1982). Therefore, the concentration of air borne fine particles is an important parameter for the evaluation of the degree of hazard in an atmospheric environment. (omitted)

• 대한안전경영과학회지
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• 제7권4호
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• pp.207-217
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• 2005

Line capacity calculation has been used to determine optimum efficiency and safe train service for train scheduling plan and investment priority order throughout detecting bottleneck section. Because of some problems of Yamagisi and UIC methods for line capacity calculation, developing of the method of line capacity caculation and evaluation for the Korea circumstance is important. This paper deals with the reliability improvement on the integrated system of TPS(Train Performance Simulator), PES(Parameter Evaluation Simulator), LCS(Line Capacity Simulator) and simulation and sensitivity analysis for line capacity.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2005년도 추계학술대회
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• pp.30-39
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• 2005

Line capacity calculation has been used to determine optimum efficiency and safe train service for train scheduling plan and investment priority order throughout detecting bottleneck section. Because of some problems of Yamagisi and UIC methods for line capacity calculation, developing of the method of line capacity calculation and evaluation for the Korea circumstance is important. This paper deals with the integrated system of TPS(Train Performance Simulator), PES(Parameter Evaluation Simulator), LCS (Line Capacity Simulator) and sensitivity analysis for line capacity calculation model.