• KIEAE Journal
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• v.13 no.2
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• pp.77-84
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• 2013

Schools are one of favorable public buildings for Renewable Energy(RE) systems due to site conditions and their energy demand profiles(e.g. daytime-based use of hot water and heating/cooling). Although the government encourages schools to be equipped with RE systems, the adoption of RE systems in existing energy supply systems faces technical and financial barriers. For example, when installing a RE-based combination system(RECS) to meet the energy demand at various school scales, identifying cost effective combination of capacities of the RECS is not trivial since it usually requires technically intensive work including detailed simulation and demand/supply analysis with extensive data. This kind of simulation-based approaches is hardly implementable in practice. To address this, a simpler and applicable decision-supporting method is suggested in this study. This paper presents a simplified model in support of decision-making for optimal capacities of RECS within given budget scales and schools sizes. The proposed model was derived from detailed simulation results and statistical data. Using this model, the optimal capacities of RECS can be induced from the number of classes in a school.

• ETRI Journal
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• v.31 no.3
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• pp.263-270
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• 2009

This paper investigates linear soft combination schemes for cooperative spectrum sensing in cognitive radio networks. We propose two weight-setting strategies under different basic optimality criteria to improve the overall sensing performance in the network. The corresponding optimal weights are derived, which are determined by the noise power levels and the received primary user signal energies of multiple cooperative secondary users in the network. However, to obtain the instantaneous measurement of these noise power levels and primary user signal energies with high accuracy is extremely challenging. It can even be infeasible in practical implementations under a low signal-to-noise ratio regime. We therefore propose reference data matrices to scavenge the indispensable information of primary user signal energies and noise power levels for setting the proposed combining weights adaptively by keeping records of the most recent spectrum observations. Analyses and simulation results demonstrate that the proposed linear soft combination schemes outperform the conventional maximal ratio combination and equal gain combination schemes and yield significant performance improvements in spectrum sensing.

• Transactions of Materials Processing
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• v.8 no.5
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• pp.471-481
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• 1999

The properties of deformed products are generally dependent upon the distribution of microstureture. It is, therefore, necessary to make the distribution of microstureture uniform in order to achieve the best balance of properties in the final product. This is often a demanding task, even for conventional materials. It is become essential to achieving mechanical integrity and a desired combination of microstructure and properties. The objective mechanical integrity and a desired combination of microsttucture and properties. The objective of this study is to design the optimal die profile which can yield more uniform microstructure in hot extruded product. The microstructure evolution, such as dynamic and static recrystallization as well as grain growth, is investigated using the program com-bined with yada and Senuma's empirical equations and rigid-thermoviscoplastic finite element method. The die profile of hot extrusion is represented by Bezier-curve to define all available profile. In order to obtain the optimal die profile which yields uniform microstructure in the product the FPS(Flexible Polyhedron Search) method is applied to the present study. To validate the result of present study the experimental hot extrusion is performed and the result is compared with that of simulation.

• Journal of the Korean Solar Energy Society
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• v.35 no.6
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• pp.51-60
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• 2015

In statutes on the promotion of distribution of new and renewable energy, which were revised in 2014, daylight system and fuel cell were added in addition to existing new and renewable energy sources. This study, therefore, aimed at setting up targets for the introduction of daylight system and analyzing the installation rate of new and renewable energy which can be provided by daylight system for the aggressive use of daylight system, thereby deducting the optimal combination ratio with other new and renewable energy sources. The results of the study are as follows. First, when a prism-shaped daylight system was installed to a round indoor gymnasium among domestic indoor gymnasiums, out of a supply obligations allotment rate of 15% of new and renewable energy, the rate of daylight system was basically set at 2.5%. Second, therefore, with daylight system coming first, the lacked supply obligations rate was taken up by solar photovoltaic, solar heat and geothermal heat. In addition, using the KRESS Program, economic, technical, environmental and complexity evaluations for the upper 5% was made, deducting the optimal ratio of the system. The results produced the following optimal combination ratios: solar photovoltaic (83.3%) in economic evaluation, solar heat (8.3%) and geothermal heat (75%) in technical evaluation, solar photovoltaic (83.3%) in environmental evaluation, and solar photovoltaic (83.3%, the same as in economic evaluation) in complexity evaluation.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.42-52
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• 1986

This study involves the estimation of optimal ranges of parameters for a linear watershed model. A well-known TANK model was chosen and a linear combination of four tanks assumed. The model was used to simulate daily streamflow for six watersheds of different sizes and by a trial-and-error approach a set of optimal parameters defined. The parameters were related to watershed sizes and land use conditions. Optimal parameters for ungaged conditions were defined from the relationships; daily streamflow simulated and compared to the observed date. The simulated results were in a general agreement with the data.

• Journal of Pharmaceutical Investigation
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• v.20 no.4
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• pp.209-215
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• 1990

The activities of s-amylase, ${\alpha}-amylase$ and protease of three combination products containing digestive enzymes, antacids and herbal drugs on the Korean market were estimated. The effects of antacids and herbal drugs on the activities of digestive enzymes were investigated. Starch-saccarifying activity of s-amylase, starch-dextrinizing activity of ${\alpha}-amylase$ and protein-peptic activity of protease were estimated by Somogy, Mc'Credy, and Casein-Folin method, respectivley. The optimal pH of s-amylase, ${\alpha}-amylase$ and protease were pH 5.0, 4.8 and 7.0, rcspectively. The digestive activities at optimal pH continued about eight hours. The digestive activities of individual enzymes were reduced to 40-90% by antacids and were affected somewhat positively or negatively by herbal drugs. Enzyme activities of the combination products were also affected by pH and reaction time.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.358-361
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• 1996

In this paper, we discuss decentralized optimal fault tolerant supervisory control issues on the basis of failure analysis and diagnosis from the angle of discrete event dynamic system. We address the detectability and the observability problems, and develope fault tolerant supervisory control system upon the failure analysis and diagnosis schemes. A complete min-cut is introduced and the procedure for finding the achievable or nonachievable layered optimal legal sublanguages is suggested for a preferential option among the reachable states in the controlled plant. A layered optimal supervisory control framework is proposed upon these. We extend the concept of decentralized supervisory control by considering the problem of combination of decentralized with centralized control in case pure decentralized control happens to be inadequate. We introduce the concept of locally controllable pair and present a hybrid decentralized supervisory control framework. Finally, we propose the analytical framework for a decentralized optimal fault tolerant supervisory control systems.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.1
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• pp.1-16
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• 1998

The zone clustering problem arising from several area such as deciding the optimal location of ambient measuring stations is to devide the 2-dimensional area into several sub areas in which included individual zone shows simimlar properties. In general, the optimal solution of this problem is very hard to obtain. Therefore, instead of finding an optimal solution, the generation of near optimal solution within the limited time is more meaningful. In this study, the combination of a genetic algorithm and the modified k-means method is used to obtain the near optimal solution. To exploit the genetic algorithm effectively, a representation of chromsomes and appropriate genetic operators are proposed. The k-means method which is originally devised to solve the object clustering problem is modified to improve the solutions obtained from the genetic algorithm. The experiment shows that the proposed method generates the near optimal solution efficiently.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.273-275
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• 2012

In apartment building with column structure, reinforcing bar of the column is constructed mainly using gas pressure welding job. Therefore, gas pressure welding job in very critical process is construction apartment building with column structure. The purpose of this study is to analyze productivity of gas pressure welding work in column structure apartment using Web-CYCLONE. In this study, a CYCLONE model was developed for the productivity analysis of gas pressure welding work. Through this model, the optimal combination of the resources was obtained. This study will be utilized in the future as a useful tool of productivity analysis and the determination of an optimal combination of resources for gas pressure welding in apartment with column structure.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.109-112
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• 2006

In the recent studies, various types of multi mode electric variable transmission for hybrid electric vehicle have been proposed. Multi mode electric variable transmission consists of two or more different type planetary gear hybrid powertrain system(PGHP), which can change its power flow type by means of clutches for improving transmission efficiencies. Generally the power flows can be classified into three different types such as Input split, output split nd compound split. In This paper, we present velocity and torque equations of the input-split powertrain and analyze its optimal Performances. There are six combinations of the input-split powertrain, each combination has various lever length. We find optimal planetary gear ratios for fuel economy and acceleration performance, and compare performances of each combination.