• ETRI Journal
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• v.40 no.3
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• pp.330-336
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• 2018

Free-space optical (FSO) systems have attracted much attention from both research and application perspectives owing to their many benefits, such as license-free operation, low-cost, and high data rates. This paper investigates the ergodic capacity of FSO systems, which is an important metric of system performance. The stochastic temporary laser-beam blockage, pointing errors, and atmospheric turbulence are simultaneously considered. The results illustrate that the link blockage causes a decreased ergodic capacity. We show that to maximize the ergodic capacity, there is an optimal value of the laser-beam radius at the waist, which largely depends on pointing errors; however, it is independent of the atmospheric turbulence and the probability of link blockage.

• IE interfaces
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• v.15 no.4
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• pp.349-355
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• 2002

In order to build a new factory, we must have answers regarding the following questions; 1. what is to be produced? 2. how are the products to be produced? 3. how much of each product will be produced? The answers are related to product-design, process-design and capacity-design respectively and they are used for layout-design as the input data. Especially capacity design decision provides the information regarding the number of equipments required and the balance of the line. This paper introduces a case study on the capacity design for a new factory where the retainers of ball bearing are manufactured. A simulation model is developed with ARENA for analyzing the system considered. The major objectives of the study are evaluating the performance of the line which is originally suggested by the company, and finding out alternatives for improving the system. Number of WIP between the processes are also investigated because it affects the space planning of the layout.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.277-279
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• 2005

Generally, It was used to use a unit of a Large regularity in developing Large Capacity Converter System of the electric power. Lager a capacity of a unit of regularity, more expensive cost of it. So, normally, We overcome the limit of a proper form of an electricity semiconductor which be used in application field of Large capacity electricity conversion system through the Composition of Multi-level Circuit or Dual-Mode or parallel switch. but some problem is discussed. Using parallel RC-diode circuit instead of Large Capacity diode, We implemented a circuit that it overcome the limit of a regularity with dealing current distributed by parallel RC-diode circuit.

• Journal of Power System Engineering
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• v.14 no.2
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• pp.78-83
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• 2010

This study was carried out to investigate the effect of microstructure on the damping capacity of 12Cr martensite heat-resisting steels, in case of the specimen with martensite phase contained the volume faction of ferrite phases, under 5%. The damping capacity was decreased with the increase of solution treatment temperature and time. While it was increased with the increase of tempering temperature and time. The damping capacity was higher in case of specimen with martensite single phase structure than the specimen with martensite phase contained of ferrite phases.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.2
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• pp.113-118
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• 1999

In this, sensitivity based approach to estimate BITC(bilateral interchange transfer capacity) considering the real power flow control function of FACTS devices is presented. The real power flow setting of the FACTS devices is adjusted so that it transfers the power flow from the first violation point of transmission capacity to other transmission lines in the power system, thus allowing more power to be transferred from the specified generator bus to the specified load bus. The transfer between the two bus locations is increased from this new operating condition until a violation of transmission capacity limits occurs or until the setting of the FACTS devices can no longer be adjusted. The proposed algorithm is illustrated using examples of small and real life power system.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.277-279
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• 2002

Recently, power requirement has been increasing. But the large generation unit is hardly installed because of economic and environment problem. Therefore, the concern for DG(distributed generation) is growing. Present, allowable interconnection capacity of DG for composite distributed generation is studied. In this paper, it is studied that the new interconnection capacity of DG for composite distribution system interconnected DG. We study new allowable interconnection capacity by power factor and placement. We study SERV(sending end reference voltage) variation and allowable interconnection capacity interconnected new DG.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.165-173
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• 2000

Analytic models have been developed to solve integrated production-distribution problems in supply chain management (SCM). As one of major constraints in analytic models, capacity, which is the total operation time in this paper has mostly been known or disregarded assuming infinite capacity. Also, as major factors, machine processing time to fabricate or assemble a part or product at a certain machine center in production system and vehicle processing time to deliver a product to a customer by a certain vehicle in distribution system have been fixed and regarded as a static factor, But in the real systems significant differences exit between capacity and the required time to achieve the production-distribution plan and between processing time and consumed time to process a part or product. In this paper, capacity and processing times in the analytic model are considered as dynamic factors and adjusted by the results from independently developed simulation model, which includes general production-distribution characteristics. Through experiments, we obtain the more realistic solutions reflecting stochastic natures by performing the iterative analytic-simulation procedure.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.2
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• pp.169-175
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• 2001

Most of studies on automated storage/retrieval (AS/R) system assumed that storage capacity is given, although it is a very important decision variable in the design phase. We propose a simple algorithm to estimate the required storage capacity, i.e., number of aisles and number of openings in vertical and horizontal directions in each aisle, of an AS/R system under stochastic demand, in which storage requests occur endogenously and exogenously while the retrieval requests occur endogenously from the machines. Two design criteria, maximum permissible overflow probability and maximum allowable storage/retrieval (S/R) machine utilization, are used to compute the storage capacity. This model can be effectively used in the design phase of new AS/R systems.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.66-71
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• 2014

In this study, effect of heat treatment on the microstructure and damping capacity of hot rolled magnesium alloys was investigated. The microstructure of hot rolled magnesium consisted of dendrite structure and $Mg_{17}Al_{12}$ compounds precipitated along the grain boundry. The dendrite structure was dissipated and $Mg_{17}Al_{12}$ compounds was decomposed by annealing treatment, and then they dissolved in ${\alpha}-Mg$. With an increasing the annealing temperature and time, damping capacity was slowly increased by the growth of grain size and decreasing of defects induced by hot rolling. Two kinds of magnesium alloys AZ 31 and AZ 61 after annealing showed no difference in damping capacity.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1495-1500
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• 2006

A signal system is critical point of transport capacity and train operation in urban rail transit. Today the moving block system by radio is taking place of the fixed block system by track circuit for efficiency and short headway in underground railway and right rail transit. In this study, assuming specification of a train, track and control system, the minimum headway on the moving block system and the fixed block system is researched for the maximum transport capacity.