• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.55-65
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• 2009

Due to the rapid increase of electricity demand, consideration of environmental constraints in optimal power flow (OPF) problems is increasingly important. In Algeria, up to 90% of electricity is produced by thermal generators (vapor, gas). In order to keep the emission of gaseous pollutants like sulfur dioxide (SO2) and Nitrogen (NO2) under the admissible ecological limits, many conventional and global optimization methods have been proposed to study the trade-off relation between fuel cost and emissions. This paper presents an efficient decomposed Parallel GA to solve the multi-objective environmental/economic dispatch problem. At the decomposed stage the length of the original chromosome is reduced successively and adapted to the topology of the new partition. Two subproblems are proposed: the first subproblem is related to the active power planning to minimize the total fuel cost, and the second subproblem is a reactive power planning design based in practical rules to make fine corrections to the voltage deviation and reactive power violation using a specified number of shunt dynamic compensators named Static Var Compensators (SVC). To validate the robustness of the proposed approach, the algorithm proposed was tested on the Algerian 59-bus network test and compared with conventional methods and with global optimization methods (GA, FGA, and ACO). The results show that the approach proposed can converge to the near solution and obtain a competitive solution at a critical situation and within a reasonable time.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1258-1260
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• 2005

Superconducting synchronous motors and generators have the field coil composed of superconductor with almost zero resistance at superconducting state. Therefore, co or loss at the conventional field coil is eliminated and the superconducting machine gets higher efficiency. The armature coil of the superconducting machine is composed of cower wire and supported by non-magnetic material such as FRP(Fiber Reinforced Plastic). Although a fully-superconducting machine with superconducting armature coil has been researched, it was not developed toward industrial application because of AC transporting loss and difficulty in construction of the cooling structure and so on. This paper contains the design procedure of a 1 MW superconducting synchronous motor using high-temperature superconductor only for the field coil. Especially, the armature coil is designed by water-cooling in order to dissipate Joule heat easily. Moreover, 3-dimensional electromagnetic design is conducted to get a proper design result and reduce design errors from 2-dimensional approach.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.3
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• pp.47-57
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• 2011

All solid rocket propellants are divided in two basic classes according to chemical state: homogeneous(double base) and heterogeneous (composite). Today, composite propellants are extensively used as power sources covering the range from gas generators and small rocket systems to large launch vehicles in space programs. The development of composite rocket propellants in the past was mainly directed to thermoset polymers. But, the thermoset composite propellants have the complication in formulation and fabricating process to adapt to rocket system requirements. In contrast to the thermoset propellant, the PVC plastisols composite propellants have the advantages in the view of loss in manufacturing process, low cost of raw material, and stability of the handling process even though moderate ballistic and mechanical properties. It is predicted that the application field of this class will be used more widely than any other classes.

• Environmental and Resource Economics Review
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• v.31 no.4
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• pp.571-595
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• 2022

This study theoretically analyzes the cost allocation of replacement costs that occur when existing operators have to replace circuit breakers due to the entry of new generators. We adopt the sequential equal contributions rule as the cost allocation rule, which is widely used in cost allocation problems in cooperative game theory. We derive various cost allocation plans based on several criteria and examine to what extent each alternative meets various desirable axioms. According to the analysis, (i) the alternative that excludes the cost of the new operator, residual value, and network operator and (ii) the alternative that excludes the cost of the new operator, residual value, and includes network operator are relatively superior to other schemes. We also identify a realistic plan by taking into account practical factors and analyze its axiomatic characteristics.

• Korean Journal of Materials Research
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• v.34 no.1
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• pp.34-43
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• 2024

New piezoelectric and triboelectric materials for energy harvesting are being widely researched to reduce their processing cost and complexity and to improve their energy conversion efficiency. In this study, BaTiO₃ films of various thickness were deposited on Ni foams by R.F. magnetron sputtering to study the piezoelectric and triboelectric properties of the porous spongy structure materials. Then piezoelectric nanogenerators (PENGs) were prepared with spongy structured BaTiO₃ and PDMS composite. The output performance exhibited a positive dependence on the thickness of the BaTiO₃ film, pushing load, and poling. The PENG output voltage and current were 4.4 V and 0.453 ㎂ at an applied stress of 120 N when poled with a 300 kV/cm electric field. The electrical properties of the fabricated PENG were stable even after 5,000 cycles of durability testing. The triboelectric nanogenerators (TENGs) were fabricated using spongy structured BaTiO₃ and various polymer films as dielectrics and operated in a vertical contact separation mode. The maximum peak to peak voltage and current of the composite film-based triboelectric nanogenerator were 63.2 V and 6 ㎂, respectively. This study offers new insights into the design and fabrication of high output nanogenerators using spongy structured materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.141-147
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• 2024

The measurement of strain under an electric field has been widely employed to comprehend the fundamental principles of electro-mechanical responses in ferroelectric, piezoelectric, and electrostrictive materials. In particular, understanding the strain properties of piezoelectric materials in response to electrical stimulation is crucial for researching and developing components such as piezoelectric actuators, acoustic devices, and ultrasonic generators. This tutorial paper introduces the components and operational principles of the linear variable differential transducer (LVDT), a widely used displacement measurement device in various industries. Additionally, we present the configuration of an experimental setup using LVDT to measure the strain characteristics of ferroelectric, piezoelectric, or electrostrictive materials under the application of an electric field. This paper includes simple measurement results and analyses obtained through the LVDT experimental setup, providing valuable information on research methods for the electro-mechanical interactions of various materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.738-744
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• 2017

Recently, the installation of energy storage systems (ESSs) has increased in parallel with the extension of renewable energy resources. However, there has been no concrete analysis ofthe performance verification and economic evaluation of ESSs,which makes it difficult to perform aneffective installation and operation of an ESS. In particular, there are no international technical standards and guidelines on electric ESS for frequency regulation applications. Therefore, acomprehensive study on the power quality, impact on grid, extent of contribution, and cost benefit study of ESS are strongly being required. Under these backgrounds, this paper proposes a performance verification algorithm on ESS for frequency regulation application based on ananalysis of the AGC(Automatic Generation Control) performance verification method of PJM in USA. In addition,this paper proposes an economic evaluation algorithm on a 500 MW installation of ESS for frequency regulation applications using the account settlement of an expensive gas-fired generation plant and coal-fired power generation plant. From the simulation with real ESS operation data and 500 MW installation case, it wasconfirmed that the ESS showssuperior performance toany other conventional generators and provides anannual benefit of 500 MW ESS are between 345~429 billon won.

• Applied Biological Chemistry
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• v.47 no.3
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• pp.321-324
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• 2004

Smoke rods were prepared for 2 insecticides and 5 fungicides using powdered rice chaff as a combustible carrier, and their burning characteristics were investigated. The distribution of active ingredient was investigated after the application of the granular smoke generator containing fenarimol in the connected vinyl plastic house growing cucumber. The protective effects of fungicide smoke generators were evaluated against cucumber gray mold (Botrytis cinerea) and tomato late blight (Phytophthora infestans), and compared with commercial wettable powders. Smoke rods containing powdered rice chaff showed high smoking rates of AI that were higher than commercial smoke pellets. The deposition of fenarimol on the ground of vinyl plastic house was $26.2{\pm}7.7\;ng/cm^2$ when averaged from 9 sites, and application uniformity was found. Also, the protective effects of 5 fungicidal smoke rods against plant diseases were so similar to the commercial wettable powders with no phytotoxicity that smoke rod formulations containing rice chaff as a combustible carrier could be used as an effective formulation for pesticides.

• Journal of Navigation and Port Research
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• v.45 no.6
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• pp.366-371
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• 2021

This study suggests surface wave communication, which uses a metal surface as a medium, to provide wireless communication in the extreme environment due to surrounding metal materials on vessels. The test was conducted on a G/T 265 tons tug boat to confirm the possibility of surface wave communication between a bridge and each designated space in the ship. As a result, the transmission speed was 13Mbps on average. In a test case of the bridge via the engine room, the transmission speed was 4.3Mbps on engine running and 1.2Mbps on sailing. It overcame this by partially changing the equipment installation location. Surface wave communication in bow storage, a fully enclosed space, had 8Mbps better transmission speed than wireless communication; this confirmed the superiority of surface wave communication in confined spaces on a vessel. Additional surface wave generators were designed and applied to resolve the paint issue. It is expected to use surface wave communication to implement the new wireless solution for Maritime-IoT system on vessels.

• Spatial Information Research
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• v.10 no.3
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• pp.455-468
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• 2002

Toward the systematic and efficient management of national land, National Geography Institute(NGI, National mapping agency) has been producing national basemap in automated process since middle of 1980's. Under the National Geographic Information System(NGIS) Development Plan, NGI began to produce digital maps in the scales of 1:1,000, 1:5,000, 1:25,000 since 1995. However, those of digital maps that have been generated under NGIS Development Plan need to be modified and corrected due to lack of technology and experience in making digital maps. In this context, those digital maps generated are currently in great need for improving the data dictionary. It is fully appreciated in previous research that data dictionary will be a key element far users and generators of digital maps to rectify the existing problems in digital maps as well as to maximize the application of digital maps. In this paper, we analyzed existing problems in digital maps based on previous researches and interviews with engineers in different fields of geospatial engineering. And then, the existing data dictionary has been redefined and modified. In the line of modification process, a relational matrix was established fur each topographic feature defined in the existing feature classification system. This paper presents newly proposed data dictionary which conforms to newly defined feature classification system from previous research performed by NGI.