• Journal of IKEEE
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• v.15 no.4
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• pp.261-266
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• 2011

In this paper, new efficient lighting control system for light devices is proposed to reduce power consumption and increases LED life-cycle and heat efficiency of LED lighting module. The new proposed lighting control system for light devices divides into 4 stages according to the illuminance surrounding by measuring illuminance and apply to automatic pattern lighting algorithm. And via level check will be light up for set time by applying intersection lighting algorithm of magic square pattern forming a fully symmetrical. Experimental analysis results, shows heating value and power consumption reduced to maximum 30 percent and lifetime of LED improved to maximum 60 percent in comparison with previous lighting system so applying system to LED streetlight, stable and high energy efficiency can be acquired.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.4
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• pp.135-140
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• 2009

A dynamic model to simulate LNG reliquefaction process has been developed. The model was applied to two candidate cycles for LNG reliquefaction process, which are Reverse Brayton and Claude cycles. The simulation was intended to simulate the pilot plant under construction for operation of the two cycles and evaluate their feasibility. According to the simulation results, both satisfy control requirements for safe operation of brazed aluminum plate-fin type heat exchangers. In view of energy consumption, the Reverse Brayton cycle is more efficient than the Claude cycle. The latter has an expansion valve in addition to the common facilities sharing with the Reverse Brayton cycle. The expansion valve is a main cause to the efficiency loss. It generates a significant amount of entropy associated with its throttling and increases circulation flow rates of the refrigerant and power consumption caused by its leaking resulting in lowered pressure ratio. It is concluded that the Reverse Brayton cycle is more efficient and simpler in control and construction than the Claude cycle.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.657-668
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• 2023

It's important to note that air compressors in the industrial sector are major energy consumers, accounting for a significant portion of total energy costs in manufacturing plants, ranging from 12% to 40%. To address this issue, researchers have compared forecasting models that can predict the power consumption of air compressors. The forecasting models were designed to incorporate variables such as flow rate, pressure, temperature, humidity, and dew point, utilizing statistical methods, machine learning, and deep learning techniques. The model performance was compared using measures such as RMSE, MAE and SMAPE. Out of the 21 models tested, the Elastic Net, a statistical method, proved to be the most effective in power comsumption forecasting.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.2
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• pp.68-82
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• 2018

Radiant floor heating systems with capillary tubes are energy saving systems in which hot water is circulated into capillary tube with a small diameter. In this study, the heating performance of capillary tube system is investigated in an experimental study and a simulation model. The results of the study showed that, the capillary tube radiant floor heating system maintains a more stable floor surface temperature in comparison a PB pipe system. In terms of energy consumption, the capillary tube radiant floor heating system proved to be more efficient than the PB pipe heating system at $40^{\circ}C$ of low temperature hot water supply. The difference between water temperature and room temperature can be held low for heating which saves energy. Low temperature radiant floor heating system with capillary tubes have significant advantages such as health improvement, low energy cost, optimum use of heat source(boiler) and higher operational efficiency.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.4
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• pp.17-23
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• 2012

Due to reinforcement of international environment regulation and high oil prices, interest in renewable energy is growing. Countries participating in UNFCCC are continuously putting efforts in reducing greenhouse gas after enforcing Kyoto Protocol into effect on Feb, 2005. Energy used in buildings, which relies heavily on fossil fuel accounts for about 24% of total energy consumption. In this study, air, geothermal and water source heat pump systems for an 322 $m^2$ auditorium in an office building is simulated using TRNSYS version 17 for comparing energy consumptions. The results show that energy consumptions of air, geothermal and water source heat pumps are 14,485, 10,249, and 10,405 kWh, respectively. Annual equal payments which consider both initial and running costs become 5,734,521, 6,403,257 and 5,596,058 Won. Thus, water source heat pump is the best economical choice.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.15-19
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• 2017

The fossil fuel power consumption generates $CO_2$, which causes the problems such as global warming. Also, the increase in energy consumption has accelerated the depletion of the fossil fuels, and renewable energy is attracting attention. Among the renewable energies, the solar energy gets a lot of attention as the infinite clean energy source. But, the supply level of solar cell is insignificant due to high cost of generation of electric power in comparison with fossil fuels. Thus several researchers are recently doing the research on ultra-low-cost solar cells. Also, $Cu_2O$ is one of the applied materials as an absorption layer in ultra-low-cost solar cells. Cuprous oxide ($Cu_2O$) is highly desirable semiconductor oxide for use in solar energy conversion due to its direct band gap ($E_g={\sim}2.1eV$) and a high absorption coefficient that absorbs visible light of wavelengths up to 650 nm. In addition, $Cu_2O$ has several advantages such as non-toxicity, low cost and can be prepared with simple and cheap methods on large scale. In this work, we fabricated the $Cu_2O$ thin films by reactive sputtering method. The films were deposited with a Cu target with variable parameters such as substrate temperature, rf-power, and annealing condition. Finally, we confirmed the structural properties of thin films by XRD and SEM.

• Journal of the Korean Wood Science and Technology
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• v.30 no.2
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• pp.108-114
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• 2002

Red pine(Pinus densiflora) square timbers with 14.0 cm and 16.5 cm of face size and 24 m long were dried in a vacuum-press kiln and in a radio-frequency/vacuum(RF/V) kiln to compare drying rate, moisture content(MC) distribution and specific energy. RF/V drying rate was higher than vacuum-press drying rate. The effect of size of cross section on the RF/V drying rates were more pronounced than those of vacuum-press drying. The longitudinal- and the transverse MC distribution of dried square timber showed convex profile for the vacuum-press drying and concave profile for the RF/V drying. Moisture gradient of width direction was similar to the thickness direction in vacuum-press dried square timber and was more slight than that of the thickness direction in the RF/V dried large square timber. The specific energy consumption curve increased as MC decreased. Specific energy(kWh/kg of water evaporated) of the vacuum-press process required more than that of the RF/V process.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.351-357
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• 2022

A conventional seawater reverse osmosis (SWRO) and a forward osmosis (FO) and reverse osmosis (RO) hybrid process to produce 1,000 m³/d of fresh water, were designed and compared in terms of carbon emission. When FO was adapted for the osmotic dilution, the required pressure for RO decreases, and thus energy consumption decreases. The decrease in carbon emission by decreased energy consumption (up to -0.73 kgCO₂/m³ using coal as the energy source) was compared with the increase in carbon emission by the FO system (+0.16 kgCO₂/m³), which is a function of various factors such as the number of FO modules and energy consumption. The comparison revealed that the FO-RO process causes less carbon emission compared with the SWRO process when the energy sources are coal and oil. However, if energy sources with low carbon emission such as solar, wind, and nuclear energy are selected, the carbon emission of the FO-RO process becomes higher than that of the SWRO process. This implies that the type of energy source is a key factor to determine the necessity of the FO-RO process from the aspect of carbon emission.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.51-57
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• 2020

WSN is a wirelessly configured network of sensor nodes with limited power such as batteries. If the sensor node's battery is exhausted, the node is no longer available. Therefore, if the network is to be used for a long time, energy consumption should be minimized. There are many Wireless Sensor Network Protocols to improve energy efficiency, including Cluster-based and chain-based Protocols. This paper seeks to examine the performance evaluation of routing protocols studied separately for the improvement of performance in wireless sensor network. The criteria for comparison were selected as the LEACH protocol, a representative hierarchical routing protocol, and the comparison targets considered CHEF and FLCFP and LEACH-DFL routing protocols with Fuzzy Logic. Various criteria for performance comparison were presented in this paper, and the performance was compared through simulation of each protocol. The purpose is to present a reference point for comparing the performance of other protocols through the performance comparison of CHEF, FLCFP, and LEACH-DFL, protocols with LEACH and Fuzzy Logic, and to provide additional design methods for improving the performance of protocols.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1025-1032
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• 2014

The effective energy management method will provide the significant advantage to the residential customers under real time pricing plan since it can reduce the electricity charge by controlling the energy consumption according to electricity rate. The earlier studies for load management mainly aim to minimize the electricity charges and peak power but put a less emphasis on the human comfort dwelling in the residence. The discomfort and displeasure from the energy management only focusing on reduction of electricity charge will make the residential customer reluctant to enroll the real time pricing plan. In this paper, therefore, we propose optimal load control strategy which aim to achieve not only minimizing the electricity charges but also maintaining human comfort by introducing "the human comfort coefficient." Using the human comfort coefficient, the energy management system can reflect the various human personality and control the loads within the range that the human comfort is maintained. Simulation results show that proposed load control strategy leads to significant reduction in the electricity charges and peak power in comparison with the conventional load management method.