• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.36-40
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• 2015

In Korea, new total energy-saving solution has planned to build test-bed in underground subway station. Breaking energy is one of the most energy saving method in railway, but it has not be fully used up for economical purpose. This paper demonstrates on energy saving technology application including breaking energy and heating energy to underground subway station. It also offer solution of optimization of power energy flow. Moreover, economic feasibility analysis performed for undergound test bed constuction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.4
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• pp.137-144
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• 2016

Commercial buildings account for a significant proportion of the total building energy use in Korea, and cooling energy, in turn, accounts for the largest proportion of total energy consumption in commercial buildings. Under this circumstance, chiller staging is considered to be a reasonable and practical solution for cooling energy saving. In this study, the part-load ratio and the operating characteristics of a vapor compression chiller were analysed within an office building. In addition, energy consumption among different chiller staging schemes was comparatively analysed. As a result, significant proportions of total operating hours, cooling load and energy consumption turned out to be in the part load ratio range from 0% through 50%, and thus energy consumption was significantly affected by the chiller COP at low part-load conditions, indicating that the chiller operation at the part-load is an important factor in commercial buildings. In addition, utilizing a sequential chiller staging scheme can reduce the annual cooling energy usage by more than 10.3% compared to operating a single chiller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3B
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• pp.247-254
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• 2009

Over the last decade multiple-input and multiple-output (MIMO) systems have been actively researched and started to be deployed in wireless communications owing to the significant increase in channel capacity. In this paper, we propose a energy saving MAC protocol in systems by focusing on energy efficiency instead of capacity maximization. We considers the energy consumption together with the tradeoff between reliability (i.e., diversity) and throughput (i.e., multiplexing gain), and dynamically chooses an appropriate number of antennas for transmission. In computing the total energy consumption, we counts circuit energy as well as transmission energy. Naturally the circuit energy consumption is directly proportional to the number of active antennas. Through numerical analysis, we confirm that our power saving MAC scheme for MIMO considerably saves energy consumption compared to conventional capacity maximization schemes that use a fixed number of MIMO channels, for a given outage constraint. Our finding is that the capacity maximizing communication which possibly can be regarded best in terms of energy efficiency gives a different solution from the energy minimizing communication.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.227-230
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• 2009

Currently the country's foreign energy dependence reaches approximately 97% and the total energy consumption percentage of buildings(commercial and domestic parts) reaches approximately 24%. Building energy saving by enhanced insulation will be very important issue. Therefore, the solution is required to reduce energy loss and increasing displeasure caused by excessive influx of solar energy through windows, to solve the problems like decoloration on indoor furniture an clothes by harmful ultraviolet rays, air conditioning and increased cost. This research used for commercialization and ills semination by basic information through a evaluation on insulation performance of the window of high efficiency energy equipment which can improve the insulation performance.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.579-589
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• 2012

To reduce extensive energy costs of the internal recycling for the purpose of denitrification in the advanced wastewater treatment, a post-treatment process using an electro-coagulation to treat nitrate in the secondary effluents is evaluated in this study. Removals of phosphorus and organics in the secondary effluents by the electro-coagulation were also evaluated to propose an alternative advanced wastewatert treatment process. A series of experiments of the electro-coagulation were carried out with the following 4 different samples: synthetic solution containing nitrate only, synthetic solution containing nitrate as well as phosphorus, secondary effluents from activated sludge cultivated in laboratory, and secondary effluents from real wastewater treatment plants. Removals of nitrate and phosphorus in the synthetic solution were 30 and 97 % respectively, which verified the feasibility of the process. Removals of nitrate, phosphorus and COD in the secondary effluents from the cultivated sludge in laboratory were 49, 90 and 19 % respectively. Removal efficiency of the total nitrogen, nitrrate, phosphorus and COD in the secondary effluent from real wastewater treatment plant were 50, 61, 98 and 80 % respectively. The removal of the total nitrogen was less than the nitrate as expected, which is due to the formation of ammonia nitrogen in the cathode. But the proposed scheme could be an energy saving and alternative process for the advanced wastewater treatment if further studies for the process optimization are carried out.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.5
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• pp.594-603
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• 2004

Several desiccant cooling systems have been developed in terms of cost and performance. In this study a fin-tube exchanger has been used for liquid desiccant dehumidification system. This dehumidifier has been designed to study the absorption characteristic of the aqueous triethylene glycol(TEG) solution which has the flow range from 20 to 50 LPM. The dehumidifier performance characteristics of working factor variables such as inlet solution flow rate, air flow rate, solution concentration and brine temperature have been analyzed. This dehumidifier has the ability to provide running while saving the latent heat load of total energy. The result of this experiment can provide useful data for hybrid air conditioning system.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.114-120
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• 2012

Eco-driving technique for electric vehicles (EVs) is investigated in this paper. Many findings on EVs have been reported; however, they did not deal with eco-driving from the viewpoint of theoretical study. The authors have developed an energy-saving driving technique - the so-called "eco-driving" technique based on dynamic programming (DP). Optimal speed profile of an EV, which minimizes the amount of total energy consumption, was determined under fixed origin and destination, running time, and track conditions. DP algorithm can deal with such complicated conditions and can also derive the optimal solution. Using the proposed method, simulations were run for some cases. In particular, the author ran simulations for the case of a gradient road with a traffic signal. The optimization model was solved with MATLAB.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.13-24
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• 2021

Tunnel boring machine (TBM) is widely used for tunnel excavation in hard rock and soft ground. In the perspective of TBM-based tunneling, one of the main challenges is to drive the machine optimally according to varying geological conditions, which could significantly lead to saving highly expensive costs by reducing the total operation time. Generally, drilling investigations are conducted to survey the geological ground before the TBM tunneling. However, it is difficult to provide the precise ground information over the whole tunnel path to operators because it acquires insufficient samples around the path sparsely and irregularly. To overcome this issue, in this study, we proposed a geological type classification system using the TBM operating data recorded in a 5 s sampling rate. We first categorized the various geological conditions (here, we limit to granite) as three geological types (i.e., rock, soil, and mixed type). Then, we applied the preprocessing methods including outlier rejection, normalization, and extracting input features, etc. We adopted a deep neural network (DNN), which has 6 hidden layers, to classify the geological types based on TBM operating data. We evaluated the classification system using the 10-fold cross-validation. Average classification accuracy presents the 75.4% (here, the total number of data were 388,639 samples). Our experimental results still need to improve accuracy but show that geology information classification technique based on TBM operating data could be utilized in the real environment to complement the sparse ground information.