• International Journal of Naval Architecture and Ocean Engineering
• /
• v.13 no.1
• /
• pp.367-378
• /
• 2021

This paper develops a dynamic regression model to quantify the contribution of key external factors to operational energy efficiency of ships. On this basis, kernel density estimation is applied to explore distribution patterns of fluctuations in operational performance. An empirical analysis based on these methods show that distribution of fluctuations in Energy Efficiency Operational Indicator (EEOI) is leptokurtic and fat tailed, rather than a normal one. Around 85% of fluctuations in EEOI can be jointly explained by capacity utilization and sailing speed, while the rest depend on other external factors largely beyond control. The variations in capacity utilization and sailing speed cannot be fully passed on to the energy efficiency performance of ships, due to complex interactions between various external factors. The application of the methods is demonstrated, showing a potential approach to develop a rating mechanism for use in the legally binding framework on operational energy efficiency of ships.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.7 no.2
• /
• pp.37-42
• /
• 2011

Dedicated outdoor air(DOA) system which conditions the outdoor air separately is superior to conventional Cooling + reheating system with respect to energy consumption and indoor comfort. Since the sensible and latent load characteristics of indoor and outdoor are different, it is more efficient to treat them separately. In this study, cycle analysis and on-site performance test of DOA system have been conducted. The study shows that DOA requires 50% less equivalent energy than the conventional system. The on-site performance test of a prototype shows that the coefficient of performance(COP) of the DOA system is 37% higher than the conventional system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.17 no.4
• /
• pp.68-78
• /
• 2021

In order to solve the increasing deterioration of the energy shortage problem, ground-source heat pump (GSHP) systems have been widely installed. The control method is a significant component for maintaining the long-term performance and for reducing operation cost of GSHP systems. This paper presents the measurement and analysis results of the cooling performance of a GSHP system using capacity control with outdoor air temperature. For this, we installed monitoring equipments including sensors for measuring temperature, flow rate and power consumption, and then monitored operation parameters from July 9, 2021 to October 2, 2021. From measurement results, we analyze the effect of capacity control with outdoor air temperature on the cooling performance of the system. The average performace factor (PF) of the heat pump was 6.95, while the whole system was 5.54 over the measurement period. Because there was no performance data of the existing GSHP system, it was not possible to directly compare the existing control method and the outdoor air temperature method. However, it is expected that the performance of the entire system will be improved by adjusting the temperature of cold water produced by the heat pump, that is, the temperature of cold water on the load side according to the outside air temperature.

• Nuclear Engineering and Technology
• /
• v.41 no.6
• /
• pp.785-796
• /
• 2009

A KALIMER-600 concept which is a type of sodium-cooled fast reactor, has been developed at KAERI. It uses sodium as a primary coolant and is a pool-type reactor to enhance safety. Also, a supercritical carbon dioxide ($CO_2$) Brayton cycle is considered as an alternative to an energy conversion system to eliminate the sodium water reaction and to improve efficiency. In this study, a simplified model for analyzing the thermodynamic performance of the KALIMER-600 coupled with a supercritical $CO_2$ Brayton cycle was developed. To develop the analysis model, a commercial modular modeling system (MMS) was adopted as a base engine, which was developed by nHance Technology in USA. It has a convenient graphical user interface and many component modules to model the plant. A new user library for thermodynamic properties of sodium and supercritical $CO_2$ was developed and attached to the MMS. In addition, some component modules in the MMS were modified to be appropriate for analysis of the KALIMER-600 coupled with the supercritical $CO_2$ cycle. Then, a simplified performance analysis code was developed by modeling the KALIMER-600 plant with the modified MMS. After evaluating the developed code with each component data and a steady state of the plant, a simple power reduction and recovery event was evaluated. The results showed an achievable capability for a performance analysis code. The developed code will be used to develop the operational strategy and some control logics for the operation of the KALIMER-600 with a supercritical $CO_2$ Brayton cycle after further studies of analyzing various operational events.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.4
• /
• pp.129-139
• /
• 2010

This paper presents a basic energy performance data of microturbine, renewable Energy(BIPV and Solar Collector System) and a hybrid energy system(geothermal system and microturbine) installed in hospital building. The efficiency of solar collector and BIPV system was 30[%], 10[%] individually, and lower than micro turbines. Finally, in energy performance aspect, microturbine and geothermal source heat pump system were a high-efficiency system in hospital building. It is confirmed hybrid energy systems also show the most powerful alternative energy system for green hospital building from the simulation results.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2010.06a
• /
• pp.81-82
• /
• 2010

Emerging global economic growth and increasing demand for energy supply and demand imbalance and the excessive use of fossil fuels existing the rapidly increasing greenhouse gas emissions and resource depletion of global energy crisis is deepening. Accordingly, improvement of living conditions around and through the natural ecological preservation and the need for a comfortable life for the meeting the importance of energy management and consumption are emerging. Many in the field of architecture for energy-saving measures, and conducting research and verify green building energy ratings and low energy for the initial steps that can be verified from the Energy Performance of BIM(Building Information Model) technology development and commercialization of the building energy to predict the performance objectively, leverages technology in an existing building energy performance analysis and possibilities of BIM-based green building process presented. In this study, using BIM for existing building energy performance analysis of data collected through the objective and efficient management of the energy it consumes Mapping and Management Plan is to research on.

• Structural Engineering and Mechanics
• /
• v.89 no.4
• /
• pp.383-397
• /
• 2024

To improve the vibration control performance and applicability of traditional particle tuned mass damper (PTMD) and realize the significant characteristic of lightweight design, this study proposes a novel particle tuned mass inerter system (PTMIS) by introducing inerter system (IS) to the PTMD. In the study, the motion equation of single degree of freedom (SDOF) structure attached with PTMIS is established first, then the variation law of the system's vibration reduction performance (VRP) is discussed through parameter analysis, and it is compared with the PTMD to analyze its VRP advantages. Finally, its vibration reduction (VR) mechanism from the perspective of core control force and energy analysis is explored, and its cavity relative displacement from the application perspective is analyzed. The results show that the PTMIS can remarkably improve the vibration control effectiveness of the PTMD. The reason is that the inerter can store energy and transfer the energy to the cavity and particles, which further stimulates the interaction between the two parts, thereby improving the nonlinear energy consumption effectiveness. Also, the IS can amplify the damping element's energy dissipation efficiency. In addition, the PTMIS can effectively reduce the working stroke of the PTMD, and through the analysis of the lightweight characteristics of the PTMIS, it is found that its lightweight advantage can reach nearly 100%.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.1
• /
• pp.57-62
• /
• 2005

Grid-connected photovoltaic (PV) systems were installed and monitored at the field demonstration test center (FDTC) in Korea in October 2002. Before long-term field testing of installed PV systems, the performances of PV components were evaluated and compared through short-term performance tests of each of the PV system components such as power conditioning system and PV module under standard test conditions. A data acquisition system has been constructed for measuring and analyzing the performance of PV systems to observe the overall effect of environmental conditions on their operation characteristics. Performances of PV systems have been evaluated and analyzed not only for component perspective (PV array, power conditioning unit) but also for global perspective (system efficiency, capacity factor, electrical power energy) by review of the field test and loss factors of the systems. These results indicate that it is highly imperative to develop an optimum design technology of grid connected PV systems. The objective of this paper is not only to evaluate and analyze the performance of domestic PV systems application through long-term field testing at FDTC but also to develop evaluation, analysis and optimum technology for long-term stability and reliability of grid-connected PV systems in Korea.

• Journal of Advanced Marine Engineering and Technology
• /
• v.11 no.1
• /
• pp.53-62
• /
• 1987

The Performance of Pre-combustion Chamber Diesel Engine mainly depends upon the compression, combustion and Expansion Processes. The analysis of varying tendency of the work factors for crank angles during these processes, which are consisted of 5 items such as exothermic energy, flow work, work in nozzle part, kinetic energy and cooling energy, are considered important as basic elements for effective combustion and performance improvement. In this paper, varying tendencies of the theoretical factors are investigated with pressure data through experiments. By the results, the trends of work factors are presented as basic data for comparing the influencing effects on work.

• Journal of the Korean Solar Energy Society
• /
• v.34 no.3
• /
• pp.82-88
• /
• 2014

Using low outdoor temperature, free cooling system is used in a data center or industrial air-conditioning for energy saving. Because use of IT equipment has increased in some office building recently, there is a growing trend towards using free cooing system. Free cooling system performance is influenced by outdoor temperature. Therefore the performance is different with regions. In this study, performance characteristic of free cooling system is analysed and energy reduction is compared with some regions. Selected regions are 4 cities; including Ulsan analyzed in preceding research, Seoul, ChunCheon and Daejeon. The Aspentech software HYSYS 8.0v was used to conduct the analysis of free cooling system based on temperature per hour of 4 cities in 2013, respectively. The main result is following as. Free cooing system in this study has energy saving effect when outdoor temperature below $7^{\circ}C$. Becuase temperature of Chuncheon is relatively low, using free cooling system can conserve most air-conditioning energy. Energy reduction amount of Seoul is 11%, Chuncheon is 17.5%, Deajeon is 15%, Ulsan is 14%. In case of large scale of air-conditioning, it is reasonable to use free cooling system although the system is used in Seoul.