• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2106-2112
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• 2013

In a traditional hydraulic elevator, elevator car is descended by down control valve, and the oil hydraulic energy must be lost during the descending stroke. In this paper, hybrid type energy saving unit for a hydraulic elevator is researched to save the hydraulic energy which is lost during the descending stroke. The energy is stored as converted electrical energy, and the saved energy is reused as the auxiliary power for the ascending stroke of elevator car or the main power of other parts. The results show that the output characteristics are stable and good and the research is successful and useful to reuse the saved energy during the descending stroke of elevator car.

• KIEAE Journal
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• v.10 no.4
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• pp.87-100
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• 2010

The energy efficient design of the multiple stock housing is very important not only to save energy but also to increase sustainability in a whole city because the multiple stock housing type is dominated in the major residential supply markets in Korea. During the early design phase of the multiple stock housing type, the architect need convenient and accurate tools for evaluating energy consumptions based on building types rapidly. Building Information Modeling(BIM) is introduced as useful tool systems providing interoperability between 3rd dimensional modeling tools and environmental engineering analysis tools, and could reduce time and cost for unnecessary modeling works in the analysis. However, it is still hard to apply to building design practice and integrated energy simulation techniques because interoperability using industrial standard file formats such as IFC and bXML is still underdeveloped. Therefore, the purpose of this study is to perform the building energy simulations, to compare the results on typical building types in multiple stock housing based on BIM, and to clear the problems using industrial standard file formats between 3rd dimensional modeling and building energy simulation software. In addition, through comparisons with simulation results according to the typical building types such as building forms, orientations, and building stories, the interrelation ship and characteristics of BIM based building energy simulation software are analysed and evaluated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.1
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• pp.15-20
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• 2017

The summer climate is very hot and humid in Korea. The humidity is an important factor in determining thermal comfort. Recently, the research for dehumidification device development has been attempted to save energy that is required for the operation of the current dehumidifiers on the market. Existing dehumidification systems have disadvantages such as wasting energy to drive a compressor. Meanwhile, dehumidification systems with membranes can dehumidify humid air without increasing the dry bulb temperature so it doesn't have to consume cooling energy. In this paper, the cooling energy savings was studied when a dehumidification system was applied in a model building instead of a chiller. The sensible heat load was almost the same result, but the latent heat load was decreased by 38.9% and the total heat load was decreased by 8.5%. As a result, electric energy used to drive the compressor in a chiller was saved by applying a membrane air-conditioning system instead.

• Journal of the Korean Solar Energy Society
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• v.38 no.3
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• pp.29-36
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• 2018

The goal of this study is to retrofit the windows of residential buildings and to activate the green remodeling by verifying energy saving and indoor thermal environment. As a result of analysis of the energy saving effect of 458 units window retrofits, it was possible to reduce the energy requirement by 48.20% ~ 54.97%. According to the improvement on indoor environment, it was possible to operate by reducing heating temperature and supply time. The actual gas consumption of the heating period was reduced by 25% compared with that of the window retarder to save 28,968 thousand won of heating energy cost. Resident's satisfaction surveys were conducted one year after window retrofit. More than 80% of the respondents answered that they satisfied the improvement on window performance, indoor thermal environment and indoor sound environment. As a result, we verified the energy saving effect and the improvement on the indoor environment through window retrofits.

• Journal of Biosystems Engineering
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• v.4 no.2
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• pp.46-52
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• 1979

The water delivery hose for agricultural pump is getting popular in rural areas in korea. Friction head loss, discharge, and power requirements were measured in various discharge for different material and diameter of hose to get basic data for economical use in agricultural pump. The results attained in this study were as follows ; 1. Friction head loss increased significantly as the velocity increased, and the difference of velocity between the different diameter of hose was bigger than that between materials, which was resulted in the increase of the friction head loss. 2. Friction head loss in the case of that the velocity with 2m/sec was constant was about 3.53 to 4.01 m/100m in the diameter 3" and about 2.30 to 3.10 m/100m in the diameter 4". Material A of diameter 3" showed the maximum value 8.4m/100m in Reynolds number $2.0\times10^5$, 4" got the minimum value 2.24m/100m, the difference between these values was bigger than 6m per 100 meters in the friction head loss. 3. Darcy-Weisbach formular with friction coefficient [f] calculated by Nikurades formular in the smooth pipe or with friction coefficient [f] calculated on the base of C value 125 in Hazen-Williams formular was available in friction head loss of the water discharger hose in rural areas. 4. Total head increased as friction head loss increased , meanwhile total discharge decreased, and 20 percents of energy was more saved in Material C 4″pipe than Material A 3″pipe in the view point from the discharge per unit power requirement, this phenomenon suggested that long distance pipe would be advantage in larger diameter pipe for save of energy. for save of energy.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.5
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• pp.231-238
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• 2017

A Class B device in LoRaWAN periodically receives a Beacon message from a gateway for synchronization, and it also periodically activates a ping slot to receive data from the server. In this paper, we save energy consumption by controlling the beacon-less operation which is immediately started on the packet loss. In addition, we propose a method that the server inactivates the ping slots of a device according to the amount of messages, which have to be received from the server, to save energy consumption resulting from activated but unused empty slots. The experiment with the 20% of packet loss rate showed that the reduced beacon-less operation and the inactivation of the ping slot decrease the energy consumption by 96.7% and 60% as compared to the existing method.

• Journal of the Korean Solar Energy Society
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• v.26 no.2
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• pp.35-42
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• 2006

Solar Thermal-Electric Integrated system can be used to generate heat and electricity simultaneously and can improve indoor all qualify. So, it can save heating and electricity cost as it operates at relatively lower temperatures. In this study, one pv module was fixed on a normal wall and a pv module was mounted on a solarwall. And a ventilation fan in the solar energy cogeneration panel was operated from 12:00 to 17:00 hours. Experimental results are recorded and anaysized. The comparison of results show that the temperature of PV on solar energy cogeneration panel was decreased by $7{\sim}9^{\circ}C$ and the electrical output was improved by $2{\sim}3W$ compared with a PV system without solarwall.

• New & Renewable Energy
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• v.5 no.3
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• pp.40-48
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• 2009

Recovered heat has been considered as a renewable energy in Europe since 2008 because its great effect on energy saving and carbon decreasing in plant process. Energy saving and decreasing green gas are critical issue today, so various technologies to save energy and decrease carbon dioxide in plant process have been applied to many industrial area. In this paper, the feasibility of condenser heat recovery by heat pump in power plant for district heating and fuel line preheating were reviewed by verifying energy (heat) balance and mass balance of power plant model. Some ways to compose proper system to recover heat of condenser are suggested and their possibilities are also reviewed. Limitations on heat recovery in power plant are also reviewed. The results are verified by calculating input/output energy based on actual performance test data of Taean Thermal Power Plant in Korea. There is noticeable improvement of plant performance in some cases which demand low temperature (<100 C) heat like distrcit heating, fuel line heating, and so forth.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.459-466
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• 2004

In order to save the energy in apartment houses, it is essential that the energy amount consumed in heating per household should be surveyed and analyzed according to heating method, which can be classified into unit, central and district methods. As a basis, we selected the household with nominal area of 32 py. because it accounts for the most percentage in Korea. It is estimated that the gas amount for cooking is 90 ㎥ and the energy amount for hot water supply is 11.41 GJ for a year, which is necessary to calculate the heating energy. Through the survey of actual energy consumption in Seoul and Gyeonggi, the energy amount used in heating can be obtained according to the heating type: 26.02 GJ/year for the unit heating, 28.09 GJ/year for the central heating and 40.61 GJ/year for the district heating.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.4
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• pp.167-174
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• 2018

The geothermal heat pump systems were installed for heating and cooling of public buildings in Jincheon Eco-friendly Energy town. The heat pump system was operated at night to save on operational costs, and the cold heat was stored in thermal energy storage (TES). In this study, the performance of geothermal heat pump systems with the TES during the summer season was analyzed, and the operational costs with and without the TES were compared. The electric chiller model was used to simulate a heat pump applied without the TES system. Electric rates of each system were measured to calculate operational costs. When the TES is used in the air conditioning system, the electric load (30.4 MWh) calculated in the daytime can move to off-peak load time, and the operational cost is reduced by 36~54%.