• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.109-114
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• 2009

The dominant heating system used in Korean residential apartment buildings is a hydronic radiant floor heating system, known as the Ondol system. The most common control strategy applied to this traditional hydronic radiant system is a simple on-off control that intermittently supplies "hot water of a fixed temperature" at a "constant flow rate" to each room. However, the current problems with the aforementioned control are as follows: (1) since the simple on-off control is usually based on a one point measured temperature (a signal from a thermostat installed in a living room) in each dwelling unit, heating energy use for unoccupied rooms as well as a difference in temperatures between spaces (master bedroom, living room, bedroom1, bedroom2) can occur occasionally. (2) the most widely used residential water splitter has static valves, and is thus not able to change the flow rate to each room depending on the space heating load. In other words, the ratio of flow rates to rooms is fixed after construction, resulting in over- or under-heating and an improper use of energy. The aim of this paper is therefore to investigate the differences in the system's performance between control strategies in terms of the flow rate control and sensor location. It is shown that energy savings of control strategies are strongly influenced by occupant schedule.

• Journal of Drive and Control
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• v.17 no.3
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• pp.26-32
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• 2020

In modern society, the energy-saving problem of industrial vehicles is economically and environmentally critical. Energy savings using the potential energy of forklifts are one of the viable solutions to resolving this problem. The basic concept of this study is to operate the hydraulic motor and recharge the battery using the flow rate from the cylinder when loading heavy objects and lowering the fork. To save energy, the torque and rotational speed of the generator should be optimized according to the load and descent speed to increase efficiency. To this end, we propose a system that optimizes energy saving efficiency by controlling the swashplate angle of the variable hydraulic motor through the GA(Genetic-Algorithm). The results were verified by building and comparing fixed motor models and variable motor models using the AMEsim. The results of the study show that the proposed optimized swashplate angle increases the energy saving efficiency by approximately 6%-8%, depending on the working conditions.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.3
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• pp.27-35
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• 1994

As a study on the method for energy-saving of the neon sign, this paper has systematically investigated the quantity of energy-consumption of the sign through a long period of time, according to the changes of the sign's ON/OFF speed, time ratio, etc. One neon sign(1 [kW] was built up for this. For this experiment, the ON/OFF periods(T) were set to 1.0,2.0,4.0 and 8.0[sec), and the ON time ratios(D) to 25, 50, 75 and 100 [%] respectively. Energy Analyzer was used for more accurate measurement. As the result, we found that the energy consumption of the sign had no effect on the ON/OFF period (T) when T was more than 2.0(sec), but that the energy consumption was decreasing when T was less than 2.0[sec]. The greatest value in the energy-saving of the sign appeared when the values of T and D were small altogather. And under the conditions, the energy consumption with T=1.0[sec) and D= 25[%] decreased 83.0[%] in comparison with the continuous ON case.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.103-109
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• 2014

It is important to control the amount of supply water flow rate at all kinds of HVAC systems in order to maintain IAQ and energy efficiency. The most of buildings installed geothermal heat pumps is using fixed water flow rate in spite of the excellent performance of geothermal heat pumps. Especially when the air-conditioning load is low, the flow rate control may be possible to save energy to operate. However, it is effective to apply the variable flow control system in order to reduce energy consumption. Therefore, the purpose of this study, change a water flow rate and improve the whole performance of the geothermal heat pump. Geothermal heat pump system is modeled after the selection of the applied building, by setting the flow rate control to be analyzed through a simulation of performance evaluation. Building energy saving according to the flow rate of the ground circulating water analyze quantitatively and to investigate the importance of the flow control.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.774-777
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• 2005

In this paper, a constant frequency phase shifting PWM controlled voltage source full bridge-type series load resonant high-frequency inverter using the IGBT power modules is presented for innovative consumer electromagnetic induction heating applications such as a hot water producer, steamer and super heated steamer. The full bridge arm side link passive quasi-resonant capacitor snubbers in parallel with the each power semiconductor device and high frequency AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is discussed and evaluated on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency soft switching PWM inverter topology, what is called class DE type. including the variable-power variable-frequency(VPVF) regulation function can expand zero voltage soft switching commutation range even under low output power setting ranges, which is more suitable and acceptable for induction heated dual packs fluid heater developed newly for consumer power utilizations. Furthermore, even in the lower output power regulation mode of this high-frequency load resonant tank high frequency inverter circuit it is verified that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.8-18
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• 2014

Building simulation is used in a variety of sectors. In its early years, building simulation was mainly used in the design phase of a building for basic functions. Recently, however, it has become increasingly important during the operating phase, for commissioning and facility management. Most building simulation tools are used to estimate the thermal environment and energy consumption performance, and hence, they require the inputting of hourly weather data. A building simulation used for prediction should take into account the use of standard weather data. Weather data, which is used as input for a building simulation, plays a crucial role in the prediction performance, and hence, the selection of appropriate weather data is considered highly important. The present study proposed a technique for generating real-time weather data files, as opposed to the standard weather data files, which are required for running the building simulation. The forecasted weather elements provided by the Korea Meteorological Administration (KMA), the elements produced by the calculations, those utilizing the built-in functions of Energy Plus, and those that use standard values are combined for hourly input. The real-time weather data files generated using the technique proposed in the present study have been validated to compare with measured data and simulated data via EnergyPlus. The results of the present study are expected to increase the prediction accuracy of building control simulation results in the future.

• Journal of Bio-Environment Control
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• v.24 no.4
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• pp.317-325
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• 2015

This paper attempts to present a review about simulation of different greenhouse parameters and energy supplying techniques by using building energy simulation, to find out the optimal solution for keeping greenhouse microclimate favorable for the crop production. The objectives of conducting this study were, to describe the various energy systems and techniques used for the greenhouse energy management and efficiency analysis of these technologies by using building energy simulation. We describe different models to understand the behavior of the energy saving technologies with respect to the resources available and different outside climatic conditions. We identified main features of the building energy simulation software, that enable users, to simulate hybrid agricultural building projects by using user defined parameters. At the end of the paper we draw some important concluding remarks on the basis of reviewing all the investigators contributions for the developments of simulation model of agricultural greenhouse energy management, using a building energy simulation software specifically TRNSYS. In conclusion, this paper provides information that TRNSYS have great potential for agricultural buildings energy simulation along with the renewable energy resources and energy saving techniques. This review paper provides aid to greenhouse researcher and energy planner for the future studies of greenhouses energy planning.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1451-1459
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• 2011

Recently, low energy houses have become an essential issue globally and various subsidy programs are ongoing to penetrate. All-electric houses which are another type of low energy houses or zero carbon houses are being developed. These houses consider new & renewable energy and demand side management programs in the construction and the diffusion process because these programs are essential policies to use energy resources reasonably. This paper shows a simulation methodology to control home appliances in all-electric houses considering the electricity consumption pattern of residents. The simulation is a first step to estimate energy saving of the house in a practical manner.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1300-1305
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• 2009

The energy conservation in buildings affects environmental preservation as well as economic benefits, and creates the comfortable indoor environment set for the inhabitants. Especially, apartment buildings show ever-increasing energy consumption with large-sized and high-class tendency, thus energy saving counterplans are needed. The present study is to develop an optical control algorithm by using heating load curve according to the outdoor temperature change. Heating load analysis should be performed before the present method can be applied. Dynamic heating load simulations are performed by resistance-capacitance method. Results show that heating load decrease linearly according to the increase of outdoor temperature.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.5
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• pp.575-582
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• 1988

This paper presents an energy analysis on the VAV system of 10-story building in Seoul using DOE-2 program and Modified Bin Method. The use of VAV system is an excellent means of saving energy in new buildings and/or retrofit. The fan control techniques considered are cycling, discharge dampers, inlet vanes, and motor speed control. The monthly and annual energy consumption is calculated for fan control techniques, components, and chiller types. The results of annual fan electricity use are compared using DOE-2 and Modified Bin Method, and show fairly good agreement. In addition, factors affecting energy consumption are also described.