• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.2
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• pp.1-6
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• 2016

Several efforts to replace the use of existing fossil energy resources have already been made around the world. As a result, a new industry of renewable energy has been created, and efficient energy distribution and storage has been promoted intensively. Among the newly explored renewable energy sources, the most widely used one is solar energy generation, which has a high market potential. An energy storage system (ESS) is a system as required. In this paper, the design and implementation of an ESS for the efficient use of power in stand-alone street lights is presented. In current ESS applied to stand-alone street lights, either 12V~24V DC (from solar power) or 110V~220V AC (from commercial power) is used to recharge power in systems with lithium batteries. In this study, an ESS that can support both solar power and commercial power was designed and implemented; it can also perform emergency recharge of portable devices from solar powered street lights. This system can maximize the scalability of ESSes using lithium batteries with efficient energy conversion, with the advantage of being an eco-friendly technology. In a ripple effect, it can also be applied to smart grids, electric vehicles, and new, renewable storage markets where energy storage technology is required.

• Journal of Sensor Science and Technology
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• v.33 no.3
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• pp.147-151
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• 2024

The importance of Wireless Sensor Networks is becoming more evident owing to their practical applications in various areas. However, the energy problem remains a critical barrier to the progress of WSNs. By reducing the energy consumed by the sensor nodes that constitute WSNs, the performance and lifespan of WSNs will be enhanced. In this study, we introduce an energy-efficient ternary modulator that employs multi-threshold CMOS for logic conversion. We optimized the design with a low-power ternary gate structure based on a pass transistor using the MTCMOS process. Our design uses 71.69% fewer transistors compared to the previous design. To demonstrate the improvements in our design, we conducted the HSPICE simulation using a CMOS 180 nm process with a 1.8V supply voltage. The simulation results show that the proposed ternary modulator is more energy-efficient than the previous modulator. Power-delay product, a benchmark for energy efficiency, is reduced by 97.19%. Furthermore, corner simulations demonstrate that our modulator is stable against PVT variations.

• Journal of Korean Society for Quality Management
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• v.46 no.3
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• pp.651-658
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• 2018

Purpose: The algorithm described in Lim(1998) is available to determine the sample size directly given specified significance level, power and signal-to-noise ratio. We research on the efficient determination of the sample size by visual methods. Methods: We propose three graphs for investigating the mutual relationship between the sample size r, power $1-{\beta}$ and the detectable signal-to-noise ratio ${\Delta}$. First graph shows the relationship between ${\Delta}$ and $1-{\beta}$ for the given r and it can be checked whether the power is sufficient enough. Second graph shows the relationship between r and ${\Delta}$ for the given power $1-{\beta}$. Third graph shows the relationship between r and $1-{\beta}$ for the given ${\Delta}$. It can be checked that which effects are sensitive to the efficient sample size by investigating those graphs. Results: In factorial design, randomized block design and the split plot design how to determine the sample size directly given specified significance level, power and signal-to-noise ratio is programmed by using R. A experiment to study the split plot design in Hicks(1982) is used as an example. We compare the sample sizes calculated by randomized block design with those by split plot design. By using graphs, we can check the possibility of reducing the sample size efficiently. Conclusion: The proposed visual methods can help an engineer to make a proper plan to reduce the sample size.

• Journal of Power System Engineering
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• v.9 no.3
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• pp.39-43
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• 2005

Among many other alternative energy resources, small scale hydropower has been brought into attention as a reliable source of energy today, which had been relatively neglected since 1960s. Present low head of Francis turbines and small scale hydroturbines, however, have limitations in the minimum required head and flow rate for efficient operation. This study attempts to develope the Francis turbine which is expected to run efficiently even in very low head and small flow rate, so that the limitations on the conventional small scale hydropower could alleviated and competition with other alternative energy sources in the changable design conditions could attained. The Francis turbine of a new concept was designed based on changable design conditions, hydrodynamics and theory of power transmission. The result of the study shows that two stages runner is more efficient, cheaper in construction, faster responding, and easier maintaining than single stage runner of Francis turbine

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.1
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• pp.41-46
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• 2012

In this paper, An efficient circuit design algorithm considering constraint is proposed. The proposed algorithm sets up in time constraint and area constraint, power consumption constraint for a circuit implementation. First, scheduling process for time constraint. Select the FU(Function Unit) which is satisfied with time constraint among the high level synthesis results. Analyze area and power consumption of selected FUs. Constraint set for area and power constraint. Device selection to see to setting condition. Optimization circuit implementation in selected device. The proposed algorithm compared with [7] and [8] algorithm. Therefore the proposed algorithm is proved an efficient algorithm for optimization circuit implementation.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.9
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• pp.984-993
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• 2014

In this paper, we propose a design for an efficient hybrid LED street lighting management system using standalone solar photovoltaic. The proposed efficient hybrid LED street lighting management system was composed of hybrid power conditioning system, gateways, LED street lights and a monitoring server. The hybrid power conditioning system was designed to charge produced power by solar photovoltaic panels in day time, and supply power to the LED street lights in night time. If there is insufficient power, the system was designed to operate using firm power, because the system utilizes photovoltaic power. A system control algorithm allied to the lighting management system, and experimented by being configured to the functions that are able to perform real-time monitoring and remote control through the lighting management system even when absent. In the result of the efficiency analysis of the hybrid lighting management system proposed in this paper, we were able to increase the energy efficiency compared to existing lighting control systems by reducing power consumption and electricity costs.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.10
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• pp.935-940
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• 2016

Recently, wireless power transmission system is gradually extended to technology in various fields such as lighting field, electric vehicles and smartphones wireless charging system. The largest of the two elements for high transmission efficiency of the wireless power transmission system are resonant coils and power amplifiers. In this paper, in order to build a high efficient wireless power transmission system, we introduce the resonance coil manufacturing method and high efficiency power amplifier design method that operates at 6.78MHz.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.428-438
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• 2016

This paper shows the design of the 100 kW IPMSG for small hydraulic power generator. The high-efficient generator, method of the dual layer interior permanent magnet was studied to improve the method of the single layer interior permanent magnet, which is mostly used. Analysis of magnet arrangement and cogging torque was done by FEM. According to structure analysis of dual layer interior permanent magnet, the amount of usage of the permanent magnet was reduced and cogging torque was decreased as well. With these successful results, the high-efficient generator design was accomplished. Based on the results of the structure analysis, the test product was designed and manufactured. And the design values and performance outputs were compared and verified with success. Also, the economic feasibility was conducted based on the electric power generated from the test product installed at the site. By the B/C analysis, in case that only SMP was analyzed, B/C ratio was 1.24 at the discount ratio of 5.5%, which considered to be economically feasible. The study is expected to be used for the application of developing large scale high-efficient interior permanent magnet synchronous generator.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.E
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• pp.1-9
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• 1995

It is shown that two step power transformation is more efficient for the normalization of frequency distribution with the coefficient of skewness of zero in comparison with others including SMEMAX and power transformations. It is confirmed that the design low flows calculated using power and two step power transformations used in this study are generally nearer to the observed data as compared with those of SMEMAX transformation at all return periods in the applied watersheds of the Kum, Naktong and Yongsan rivers in Korea.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.143-151
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• 2011

This paper presents a survey of recent wireless power transfer systems. The issue of wireless power transfer is to achieve a highly efficient system with small positioning errors of the facilities setting. Several theories have been presented to obtain precise system design. This paper presents a summary of design theory for short range power transfer systems and detailed formulations based on a circuit model and an array of infinitesimal dipoles. In addition to these theories, this paper introduces a coil array scheme for improving the efficiency for off axis coils. In the microwave range, tightly coupled resonators provide a highly efficient power transfer system. This paper present san-overlay resonator array consisting of half wavelength microstrip line resonators on the substrate with electromagnetically coupled parasitic elements placed above the bottom resonators. The tight couplings between the waveguide and the load resonator give strong power transmission and achieve a highly efficient system, and enables a contact-less power transfer railroad. Its basic theory and a demonstration of a toy vehicle operating with this system are presented. In the last topic of this paper, harmonic suppression from the rectenna is discussed with respect to acircular microstrip antenna with slits and stubs.