• Earthquakes and Structures
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• v.6 no.1
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• pp.111-125
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• 2014

Multiple level performance of seismically isolated elevated storage tank isolated with multi-phase friction pendulum bearing is investigated under totally 60 records developed for multiple level seismic hazard analysis (SLE, DBE and MCE). Mathematical formulations involving complex time history analysis have been proposed for analysis of typical storage tank by multi-phase friction pendulum bearing. Multi-phase friction pendulum bearing represent a new generation of adaptive friction isolation system to control super-structure demand in different hazard levels. This isolator incorporates four concave surfaces and three independent pendulum mechanisms. Pendulum stages can be set to address specific response criteria for moderate, severe and very severe events. The advantages of a Triple Pendulum Bearing for seismic isolation of elevated storage tanks are explored. To study seismic performance of isolated elevated storage tank with multi-phase friction pendulum, analytical simulations were performed with different friction coefficients, pendulum radii and slider displacement capacities.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.1167-1176
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• 1995

This paper suggests a method for optimal power assignment of the satellite transponder input carriers in the Multi-level & Multi-bandwidth system. The interference and the noise effects analyzed for the optimal power assignment are intermodulation product caused by the nonlinear transponder characteristics, adjacent channel interference, co-channel interference, and thermal noise in the satellite link. The Fletcher- Powell algorithm is used to determine the optimal input carrier power. The performance criteria for optimal power assignment is classified into 4 categories according to the CNR of destination receiver earth station to meet the requirement for various satellite link environment. We have performed mathematical analysis of objective functions and their derivatives for use in the Fletcher-Powell algorithm, and presented various simulation results based on mathematical analysis. Since the satellite link, it is meaningful to model and analyze these effects in a unified manner and present the method for optimal power assignment of transponder input carriers.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.10 no.16
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• pp.129-132
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• 1987

Multi-item inventory problems can be well characterized by the nature of interaction of the quantities and timing. This interaction may be due to the effect of certain combination of orders. It is that the set-up cost of ordering individual items can be saved by jointly ordering at a time. This study finds a decision criteria of optimum inventory policy through the comparisons of individual multi-item order policy(IMP), joint multi-item order policy(JMP), augmented multi-item order policy(AMP) in cost ratio. Subsequently we assume that there exists a unique optimum order level corresponding to an optimum reorder range for the augmented multi-item order, at which a cost saying is maximum.

• Journal of Korean Society of Transportation
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• v.5 no.2
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• pp.37-54
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• 1987

The methods of the transportation plan evaluation have appearently been improved. Yet we are frequently confronted with many problems when we are trying to apply those various methods in practice. This paper aims at reviewing the major problems in the transportation plan evaluation and considering the way to resolve such kinds of problem. The selection of the evaluation criteria and the weighting systems between such criteria are the moat important things in the multi-criteria approaches. In this respect, this paper suggests some alternative evaluation criteria in consideration of the levels and the purpose of the plan. Also the increased capacities and new demands of generated trip are the main effects of the transportation investment. Nevertheless such significant effects have been neglected in the calculation of benefits due to the transportation investment in the past. Therefore this paper suggests that the surplus capacities and new demands of generated trip according to the alternative investment plans should be included in the calculation of benefits for the plan evaluation.

• Journal of Aerospace System Engineering
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• v.10 no.2
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• pp.7-13
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• 2016

Multi disciplinary approach for aerodynamics, structure, propulsion, and flight control system is necessary to develop High Altitude Long Endurance Unmanned Aerial Vehicles (HALE UAV). Various HALE UAV development trends are surveyed to understand their operational requirements. Separating the UAV Take Off Weight by 150kg, Airworthiness implementation direction for HALE UAV is studied under the current Airworthiness regulations. NATO STANAG 4671 and STANAG 4703 Airworthiness certification criteria are analyzed, and their applicability was proposed for future HALE UAV development. In addition, minimization of the risk for UAV is studied by considering probability of cumulative catastrophic failure for HALE UAV. This Hazard Risk Index can support the future UAV Airworthiness Certification Criteria.

• Fibers and Polymers
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• v.5 no.4
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• pp.297-302
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• 2004

In many engineering applications, the final decision is based on the evaluation of a number of alternatives in terms of a number of criteria. This problem may become very intricate when the selection criteria are expressed in terms of different units or the pertinent data are difficult to be quantified. The Analytic Hierarchy Process (AHP) is an effective way in dealing with such kind of complicated problems. Cotton fiber is selected or graded, in the spinning industries, based on several quality criteria. However, the existing selection or grading method based on Fiber quality Index (FqI) is rather crude and ambiguous. This paper presents a novel approach of cotton fiber selection using the AHP methodology of Multi Criteria Decision Making.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1997.10a
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• pp.223-223
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• 1997

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.23-24
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• 2017

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.4
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• pp.81-87
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• 2007

In this study, analysis of structural design criteria for the canopy actuating device has been conducted considering the aerodynamic breakaway capabilities of jettisonable canopy system. Unsteady aerodynamic loads for the opened canopy configuration at passively controlled jettision mode were computed using CFD method. The general purpose multi-body finite element code, SAMCEF Mecano, is used in the implemented analyses for the passive jettision condition. The recommended altitude and speed of aircraft was suggested as design criteria of aerodynamic breakaway capability of jettisonable canopy system as a bakup egress method when normal canopy jettison sequence malfunctioned. Aerodynamic breakaway condition of jettisonable canopy was also simulated and the fracture load conditions of canopy actuator were investigated.

• Korean Management Science Review
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• v.32 no.4
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• pp.69-80
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• 2015

The semiconductor industry is one of those in which the most intricate processes are involved and there are many critical factors that are controlled with precision in those processes. Naturally production scheduling in the semiconductor industry is also very complex and studied by the industry and academia for many years; however, still there are many issues left unclear in the problem. This paper proposes an multi-objective optimization-based scheduling method for semiconductor fabrication(fab). Two main objectives are throughput maximization and meeting target production quantities. The first objective aims to reduce production cost, especially the fixed cost incurred by a large investment constructing a new fab facility. The other is meeting customer orders on time and also helps a fab maintain stable throughput through controlled WIP balancing in the long run. The paper shows a trade-off structure between the two objectives through experimental studies, which provides industrial practitioners with useful references.