• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2127-2137
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• 2017

A virtual power plant (VPP) is a system that virtually integrates power resources based on the VPP participating customer (VPC) unit and operates as a power plant. When VPP operators manage resources to maximize their benefits, load reduction instructions may focus on more responsive VPCs, or those producing high profitability, by using VPC resources with high operation efficiency. VPCs may thus encounter imbalance problems during operation. This imbalance in operation time would bring more participation for some VPCs, causing potential degradation of their resources. Such an operation strategy would be not preferable for VPP operators in managing the relationship with VPCs. This issue impedes both continual VPC participation and economical and reliable VPP operation in the long term. An operation algorithm is therefore proposed that considers the operation time of VPC generators for mandatory reduction of power resource consumption. The algorithm is based on constraints of daily and annual operation times when VPP operators of local generators perform capacity-market power transactions. The algorithm maximizes the operator benefit through VPP operations. The algorithm implements a penalty parameter for imbalances in operation times spent by VPC generators in fulfilling their obligations. An evaluation was conducted on VPP operational effects by applying the algorithm to the Korean power market.

• ETRI Journal
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• v.32 no.5
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• pp.801-809
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• 2010

This paper presents a statistical model-based noise suppression approach for voice recognition in a car environment. In order to alleviate the spectral whitening and signal distortion problem in the traditional decision-directed Wiener filter, we combine a decision-directed method with an original spectrum reconstruction method and develop a new two-stage noise reduction filter estimation scheme. When a tradeoff between the performance and computational efficiency under resource-constrained automotive devices is considered, ETSI standard advance distributed speech recognition font-end (ETSI-AFE) can be an effective solution, and ETSI-AFE is also based on the decision-directed Wiener filter. Thus, a series of voice recognition and computational complexity tests are conducted by comparing the proposed approach with ETSI-AFE. The experimental results show that the proposed approach is superior to the conventional method in terms of speech recognition accuracy, while the computational cost and frame latency are significantly reduced.

• Structural Engineering and Mechanics
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• v.38 no.4
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• pp.429-441
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• 2011

In large-scale problem, a huge size of computational resources is needed for a reliable solution which represents the detailed description of dynamic behavior. Recently, eigenvalue reduction schemes have been considered as important technique to resolve computational resource problems. In addition, the efforts to advance an efficiency of reduction scheme leads to the development of the multi-level system condensation (MLSC) which is initially based on the two-level condensation scheme (TLCS). This scheme was proposed for approximating the lower eigenmodes which represent the global behavior of the structures through the element-level energy estimation. The MLSC combines the multi-level sub-structuring scheme with the previous TLCS for enhancement of efficiency which is related to computer memory and computing time. The present study focuses on the implementation of the MLSC on the direct time response analysis and the frequency response analysis of structural dynamic problems. For the transient time response analysis, the MLSC is combined with the Newmark's time integration scheme. Numerical examples demonstrate the efficiency of the proposed method.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.308-318
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• 2015

In order to improve the competitiveness of Korean large purse seine fishery, the purpose of this study is to find out the problems and present the improvement of the production structure of Korean large purse seine fishery by comparing to the production structure of Norwegian purse seine fishery. Norwegian purse seine fishery has been operating labor and energy-saving systems through a single wire operation and avoiding fishing competition through the introduction of IVQ system with different types of fishing vessel and obtaining benefits from Leading fishery management integrated with fish pumps and cooling water systems. In contrast, our country has a large purse seine fishery issues such as high cost and low efficiency of production structures, the volatility of mackerel resources, the lack of leading fishery management after catching fishes, the reduction of fishing ground in accordance with the North East Asia EEZ system. To solve these problems, initiatives to improve the structure of our large purse seine fishery are as follows: First, Implementing the promotion of the effective immature fishes management and establishing Korea-China-Japan resource management system. Second, the promotion of reduction of fleet size, the review of possible single fishing operation, leading out to strengthen its competitiveness by switching to energy-efficient production systems through enhanced efforts at fisheries catches steps. Third, it is necessary to realize corporate through the diversification of business areas and the large-scale commercialization of production structure.

• Journal of the Korea Safety Management & Science
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• v.17 no.1
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• pp.321-335
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• 2015

This study introduces the methods to apply and develop the integrated Cost of Quality (COQ) and Time-Driven Activity-Based Costing (TDABC) model for seeking not only quality improvement but also reduction of overhead cost. Inefficient and uneconomical COQ activities can be identified by using time driver which also maximizes the quality improvement for Prevention-Appraisal- Failure (PAF) quality costs. In contrast, reduction of the indirect cost of unused capacity resource using Quality Cost Capacity Ratio (QCCR) of TDABC minimizes overhead cost for COQ activities. In addition, linkage between Overall Equipment Effective (OEE) and Time Driver develops the integrated system of Total Productive Maintenance (TPM) and TDABC model. Lean OEE maximizes when an Unused Time (UT) of TDABC that are TPM losses and lean wastes reduces whereas the TPM Cost Capacity Ratio (TCCR) of TDABC minimizes indirect cost for non-value added TPM activities. Numerical examples are derived to better understand the proposed COQ/TDABC model and TPM/TDABC model from this paper. From the proposed model, process mapping and time driver of TDABC are known to lessen indirect cost from general ledger of comprehensive income statement with a better quality innovation and improvement of equipment.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.57-61
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• 2010

In this study, many concrete specimens were tested to investigate the variations of strength characteristics of high-strength concrete due to amount of recycled coarse aggregates, and to investigate the effect of steel-fiber reinforcement on concrete using recycled coarse aggregates. Test results showed that all of the variations of compressive, tensile and flexural strength appeared in linear reduction according to icrease the amount of recycled coarse aggregates, and steel-fiber reinforcement of 0.75% volumn of concrete recovered completely spliting tensile strength and flexual strength and recovered greatly compressive strength of concrete using recycled coarse aggregates of 100% displacement. And test results showed that the shear strength falled rapidly at 30% of replacement ratio so far as 34% of strength reduction ratio, but after that it falled a little within 3% up to the replacement ratio 100%, and steel-fiber reinforcement of 0.75% of concrete volumn recovered completely the deteriorated shear strength, moreover improved the shear strength above 50% rather than that of concrete using natural coarse aggregates.

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.4
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• pp.25-32
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• 2013

The green building is one of biggest factors to go the goal of energy saving and environmental conservation, reduction of energy consumption, friendly energy technology, recycling of resource, and environmental pollution reduction technology. The purpose of these green buildings realized by the energy-saving technology such as the exterior materials or curtain wall system. The curtain wall system is a element that come to insulated portions of building envelope that results in heat loss. The purpose of this paper is to carried out mock-up tests for exterior wall used in autoclaved lightweight concrete panels in green building practices. Mock-up test execute a mixed process between standard test procedure and complex test procedure based on AAMA 501(American Society for Testing and Materials) and ASTM 283, ASTM 330(American Society for Testing and Materials). In results, tests meet the requirements that grant values in steps of procedures provided on ASTM and AAMA. ALC panel is suitable for a exterior wall product to be gratified thermal cycling performance and structural capacity, deflection(H/200) and lateral displacement(H/50), for curtain walls.

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.2
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• pp.35-43
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• 2013

The green building is one of biggest factors to go the goal of energy saving and environmental conservation, "reduction of energy consumption, friendly energy technology, recycling of resource, and environmental pollution reduction technology. The purpose of these green buildings realized by the energy-saving technology such as the thermal bridge breaker(or thermal bridge block). Thermal bridges are localized elements that penetrate insulated portions of building envelope that results in heat loss. The purpose of this paper is to describe the technical interactions for patents of a thermal bridge breaker(TTB) used in green building practices, and be subject to investigation to TTB in the leading countries, that is, United State, Europe Union, Japan, and Korea. As a result, there are four TTB categories(roof, wall-slab connection, opening, footing) in house or building. The TTB categories is remarkable technology that is apparatus in slab-wall joints and sealing element of opening frame in walls.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.10
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• pp.33-51
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• 1997

On ATM-based wired/wireless integrated network, we apply the connection re-routing method[1] which reduced the inter-cluster handoff delay by reserving VPI/VCLs for possible inter-cluster handoff calls in advance. Additionally, we propose wired resource reservation methods, which are ausiliary method and split method, for handoff QoS guarantee of various expected services. The characteristics of these methods reserve wired connection resources based on the information on the possible inter-cluster handoff calls. With mathematical analysis, we also propose each algorithm and cost function for deciding an optimal amount in reserving resources. With numberical examples, we can see that the auxiliary method effectively reduces the cost in all cases(.alpha.>.betha., .alpha.=.betha., and .alpha.<.betha.). The split method has a little cost-reduction effects, when handoffs call does not have priority over new calls (that is, .alpha..leq..betha.) and the total capacity is relatively large. In other cases, the split method, however, has effective cost-reduction effects. The numerical resutls show that these reservation methods ca flexibly cope with the time-variant environment and meet the QoS requriements on the inter-cluster handoff calls.

• Journal of computational fluids engineering
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• v.15 no.4
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• pp.1-8
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• 2010

This article describes the numerical investigation of turbulent blood flow in the stenosed artery bifurcation under periodic acceleration of the human body. Numerical analyses for turbulent blood flow were performed with different magnitude of periodic accelerations using a modified turbulence model which was considering drag reduction of non-Newtonian fluid. The blood was considered to be a non-Newtonian fluid which was based on the power-law viscosity. In order to validate the modified $k-{\varepsilon}$ model, numerical simulations were compared with the standard $k-{\varepsilon}$ model and the Malin's low Reynolds number turbulence model for power-law fluid. As results, the modified $k-{\varepsilon}$ model represents intermediate characteristics between laminar and standard $k-{\varepsilon}$ model, and the modified $k-{\varepsilon}$ model showed good agreements with Malin's verified power law model. Moreover, the computing time and computer resource of the modified $k-{\varepsilon}$ model were reduced about one third than low Reynolds number model including Malin's model.