• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.1397-1405
• /
• 2009

In recent decades, exergy analysis has been holding spotlight as a useful tool in the design, assessment, optimization, and improvement of energy system. This paper presents the results of the energy and exergy analysis of a steam turbine cogeneration system for industrial complex using two efficiency concepts of conventional one and exergetic one. In order to obtain the destroyed exergy of each component, mathematical analysis is conducted by using exergy balance and the second law of thermodynamics, according as the parameters are changed, such as the ratio of returned process steam, process steam supplied, temperature and pressure of boiler and power. The computer program developed in this study can determine the efficiencies and exergy destroyed at each component of cogeneration system. As a result of this study, a component having the largest destroyed exergy was boiler. And closed and opened feedwater heater had the lowest one. The affects to the cogeneration system due to the variation of process steam flow and return rate of condensed water is shown that the total electric power efficiency(${\eta}_E$) is decreased as increasing the return rate of condensed water under constant process steam flow. As the boiler pressure is increased for the more production of electricity, the efficiency of cogeneration system was decreased.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.1
• /
• pp.139-144
• /
• 2023

Recently, many manufacturing companies are paying more attention to energy efficiency due to increased energy costs. Energy-efficient scheduling of production systems is a good method for energy efficiency improvement and cost reduction. In this research, we assumed the tire production problem and aim to construct a production scheduling considering specific shape module types, ordered amount for each tire, number of production modules, and the production time for each type. To facilitate effective production scheduling, we considered the types and number of shape modules currently available, and tire types that can be selected to be produced in the next stage were used as additional inputs, In addition to that, additional production was permitted to reduce the halt of production processing. Thus, an average production module utilization rate of about 62 percent was obtained.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.73-74
• /
• 2010

In this paper, Around the world for electric vehicles are gaining attention and market trends to domestic and foreign policy. Current charging method developed techniques are discussed and is proposed for domestic situations and charging ways. The electric vehicle is emerging as a result of the energy efficiency issue, the combined battery and capacitor switching is proposed to use to offset the disadvantages of each method to improve the energy efficiency offers.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.6
• /
• pp.70-75
• /
• 2021

Recently, several efforts have been made to improve the thermal efficiency of a refrigerant compressor. In this study, we attempted to improve energy efficiency ratio (EER) performance by reducing the superheat of the linear compressor. To this end, heat generated inside the compressor must be effectively dissipated. Therefore, heat dissipation was improved by processing ribs in the gap-flow region generated owing to the vibration of the compressor body. The results showed that the convective heat transfer coefficient becomes significantly high when ribs are used, increasing the heat dissipation rate. This helps improve EER by reducing the superheat of the compressor.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.49 no.5
• /
• pp.66-71
• /
• 2012

The capacity criteria have been proposed in order to select a cooperative relay node in WSNs, under the environment where direct path has a poor link gain. This process may ensure the efficiency improvement of signal transfer between source and destination and reduction of energy consumption as well. Two criteria are incorporated to select a cooperative relay node. Firstly, calculate the energy gain ratio between the relay path and the direct path. These are defined as the ratio between the energy factors of 1/g and 1/B. Each stands for an inverse of direct path gain and relay path gain. Secondly, investigate the effects of relay node's usage in WSNs through the simulation in terms of energy consumption. In conclusion, using a selected cooperative relay node based on the selected criteria is effective in terms of both energy efficiency and capacity of WSNs especially when direct path gain is relatively low.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.10B
• /
• pp.845-854
• /
• 2008

In this paper, we propose a clustering algorithm for efficient energy management of sensor network consisted of sensor nodes that have restricted energy to solve these problem. Proposed algorithm improves energy efficiency by controlling sensing power. And it has distinctive feature that is applied in various network environment. The performance evaluation result shows that the energy efficiency is improved by 5% in the case of all sensor node fixed and by $10{\sim}15%$ in the case of all sensor node moving. It is confirmed through experiment process that the proposed algorithm brings energy efficiency ratio improvement of $5{\sim}15%$ more than the existing algorithm. Proposed algorithm derived an upper bound on the energy efficiency for Ubiquitous Computing environment that have various network environment that is with ZigBee technology of IEEE 802.15.4 bases. Also, we can blow bring elevation for lifetime of sensor network greatly for lifetime of sensor node as is small. And we think that may expand practical use extent of a sensor network technology more in fast changed network environment.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.2
• /
• pp.369-376
• /
• 2021

The International Maritime Organization has developed the Energy Efficiency Design Index, an index related to carbon dioxide emissions, to enforce regulations on newly built ships. In this study, a new type of energy-saving device called the ring stator was used for 158k crude oil carriers, whose hull form was developed as a very thin after-body hull to reduce the resistance by delaying separation. The Energy-Saving Device (ESD) particularly involving the duct, is not adapted to the thin-after body hull form-like container ship. This new ring stator was developed considering these characteristics. A parametric study was conducted through Computational Fluid Dynamics (CFD) analysis using the Star-CCM+ program, and approximately 3.4 % improvement in propulsion efficiency was achieved. Further optimization investigations and experimental studies should be conducted in the future.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.679-680
• /
• 2011

This paper is developed to Energy Balance Flow show the flow of total energy resource be used nationally. The Energy Balance Flow is applicable of demand management factor through the analysis of foreign energy model of supply and demand and energy statistic data in the country. This study is based on and developed to Energy system management model is able to appraisal efficient of energy cost cutting, CO2 emission reduction and Energy saving at the national level calculated effect reached amount of primary energy to change of energy flow followed application of demand side management factor is able to appraisal quantitatively at the total energy to model of demand and supply.

• Journal of Hydrogen and New Energy
• /
• v.21 no.3
• /
• pp.220-226
• /
• 2010

The heat transfer performance improvement in closed cooling water system of an electric power generation can be achieved by a corrosion control using corrosion inhibitors. The effect of trisodium phosphate and sodium nitrite upon carbon steel at various $Cl^{-1}$ ion containing water concentrations was examined by an integrated corrosion monitoring system. Nitrite was found to be the most effective inhibitor among tested inhibitors for carbon steel. The inhibiting process is considered as adsorption of nitrite ions in oxide layer which form a passive film on the carbon steel surface.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.8
• /
• pp.1125-1131
• /
• 2013

Wireless power transmission technology has been studied variety. Recently, wireless power transmission technology used by resonance and magnetic induction field is applied to various fields. However, magnetic resonance and inductive coupling are have drawbacks - power transmission distance is short. Microwave transmission and accept techniques have been developed to overcome short distance. However, improvement in efficiency is required. This paper, propose a high-efficiency microwave energy acceptor IC(EAIC). Suggested EAIC is consists of RF-DC converter and DC-DC converter. Wide Input power range is -15 dBm ~ 20 dBm. And output voltage is boosted up to 5.5 V by voltage boost-up circuit. EAIC can keep the output voltage constant. Available efficiency of RF-DC converter is 95.5 % at 4 dBm input. And DC-DC efficiency is 94.79 % at 1.1 mA load current. Fully EAIC efficiency is 90.5 %.