• 설비공학논문집
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• 제17권8호
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• pp.746-753
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• 2005

Adsorption chillers have been receiving considerable attentions as they are energy-saving and environmentally benign systems. In order to evaluate adsorption rates, experiments were performed in the batch type adsorption apparatus. Three types of silica gels were investigated under an assortment of experimental conditions that are representatives of the actual operating environments in the adsorber of adsorption chillers. Experimental results revealed the effects of silica gel particle size, bed temperature, and fin pitch of fin tube on the adsorption rate. The $0.25\~1.18mm$ particle size of silica gel with high adsorption rate was selected as a suitable adsorbent. The measured adsorption rate became bigger with decreasing particle size. From the comparison of adsorption rate, it is found that the fin tube has about $21\%$ higher value than that of the bare tube. The effect of heat and mass flux is found to be more significant in the fin tube than in the bare tube.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.155-161
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• 2009

Desiccant systems have been proposed as energy saving alternatives to vapor compression air conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. The liquid desiccants contact the gas inside the packed column and the heat transfer and mass transfer will occur. This proposal is try study the mass transfer and heat transfer inside the packed column of dehumidifier and regenerator systems. And later on, the rates of dehumidification and regeneration that were affected by desiccant flow rates, air temperature and humidity, and desiccant temperature and all that variation will influence the performance of the systems.

• 조명전기설비학회논문지
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• 제30권1호
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• pp.8-13
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• 2016

Public institutions should replace their luminaires with LED lighting by 2020 to save energy. Because the LED lighting installation rate in schools has not yet reached the legal goal, the ESCO program feasibility was investigated. The amount of electricity used, electric rates, times of use in classrooms and fluorescent lighting maintenance costs etc., as well as the elements of lighting maintenance were analyzed. In the case of schools, the lamp usage time was so short that the ESCO projects with only energy savings were impossible. In order to execute the ESCO projects, the maintenance cost savings by replacing an existing luminaire should be considered and the introduction of the relatively cheaper tube type LED lamp than the flat type LED luminaire was required.

• 한국지열·수열에너지학회논문집
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• 제19권2호
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• pp.1-7
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• 2023

In this study, in order to reduce the amount of infiltration generated from windows among the heat loss generated in the building, energy shutters were installed on the windows to conduct experiments on the change in internal temperature and amount of infiltration due to the pressure difference between the environmental chamber and the pressure box. As a result of the experiment, when the pressure difference was 0Pa, the initial temperature of the pressure box of window was higher than that of the pressure box of the energy shutter, but when the pressure difference occurred, the internal temperature of the pressure box of the energy shutter was higher. In addition, the amount of infiltration of the energy shutter was lower than that of the windows in all experimental conditions, and it was concluded that the reduction rate of the infiltration load (of the energy shutters) could be reduced by 53.3% compared to that of the windows.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.147-158
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• 2017

Among the energy consumption in building, the heating energy takes the largest part. Therefore, it is important to minimize the heat energy loss in building for the reduction of overall energy use in construction. The most important points for the minimization of energy loss in building are insulation and airtightness. Especially, in wood houses, airtightness is very important for energy saving as well as increase of durability. However, the researches on airtightness of wood buildings have been started recently and are very deficient especially in Korea. In this study, air leakage properties and airtightness performance were evaluated for light-frame wood houses built in Daejeon and Chungnam area. Total 7 houses were evaluated, among which four houses (Case 1 to Case 4) were in the construction stage before interior finish and the other three houses (Case 5 to Case 7) were after completion of construction work. The tests for airtightness were conducted by pressurization-depressurization method, and the factors included in the measurements includes air leakage rate at 50 Pa (CMH50), air change rate at 50 Pa (ACH50), equivalent leakage area (EqLA) and EqLA per floor area. As a result of this study, key air leakage points in wood houses were found to be the gaps between floor and wall, the holes for wiring and plumbing, the double glasses windows and the entrance doors. The average value of ACH50 for the houses after completion of construction work was $3.5h^{-1}$ that was similar to Europe standard ($3.0h^{-1}$). ACH50 was proportional to EqLA per floor area but inversely proportional to the internal volume, the net floor area and the area of window.

• Journal of Communications and Networks
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• 제16권1호
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• pp.36-44
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• 2014

Exploiting the energy-delay tradeoff for energy saving is critical for developing green wireless communication systems. In this paper, we investigate the delay-constrained energy-efficient packet transmission. We aim to minimize the energy consumption of multiple randomly arrived packets in an additive white Gaussian noise channel subject to individual packet delay constraints, by taking into account the practical on-off circuit power consumption at the transmitter. First, we consider the offline case, by assuming that the full packet arrival information is known a priori at the transmitter, and formulate the energy minimization problem as a non-convex optimization problem. By exploiting the specific problem structure, we propose an efficient scheduling algorithm to obtain the globally optimal solution. It is shown that the optimal solution consists of two types of scheduling intervals, namely "selected-off" and "always-on" intervals, which correspond to bits-per-joule energy efficiency maximization and "lazy scheduling" rate allocation, respectively. Next, we consider the practical online case where only causal packet arrival information is available. Inspired by the optimal offline solution, we propose a new online scheme. It is shown by simulations that the proposed online scheme has a comparable performance with the optimal offline one and outperforms the design without considering on-off circuit power as well as the other heuristically designed online schemes.

• 한국식품저장유통학회지
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• 제4권3호
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• pp.237-243
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• 1997

Numerous variables affect product cooling rate of pressure cooling system for fruits and vegetables. These include carton vent area, initial and desired final product temperature, flow rate and temperature of the cooling air, product size, shape and thermal properties and product configuration(whether in bulk or packed in shipping cartons). This study was carried out to determine the influence of each of these variables as they affect cooling time. The opening ratio and number of the vent hole were recomended as 4∼10% and 2∼4ea., respectively, for a minimum alt flow resistance and for a uniform air flow pattern. In the cooling experiment for tomatoes and mandarins, optimum air flow rate was 0.04 m3/min.kg in terms of energy saving. The cooling air temperature should be about 2$^{\circ}C$ less than the desired final product temperature for reducing cooling time.

• 한국환경보건학회지
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• 제29권1호
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• pp.51-61
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• 2003

Pollution purification using titanium dioxide (TiO$_2$) photocatalyst has attracted a great deal of attention with increasing number of relent environmental problems. Currently, the application of TiO$_2$ photocatalyst has been focused on purification and treatment of waste water. However. the use of conventional TiO$_2$ powder photocatalyst results in disadvantage of stirring during the reaction and of separation after the reaction. And the usage of artificial UV lamp has made the cost of photocatalyst treatment system high. Consequently, we herein studied the pilot-scale design to aid in optimization of the energy-saving process for more through development and reactor design by solar light/UV lamp/ TiO$_2$system. In this study, we manufactured the TiO$_2$sol by sol-gel method. According to analysis by XRD, SEM and TEM, characterization of TiO$_2$ sol were nano-size (5-6 nm) and anatase type. Inorganic binder (SiO$_2$) was added to TiO$_2$ lot to be coated for support strongly, and support of ceramic bead was used to lower separation rate that of glass bead The influences were studied of various experimental parameters such as TiO$_2$ quantity, pH, flow rate. additives, pollutants concentration, climate condition and reflection plate by means of reaction time of the main chararteristics of the obtained materials. In water treatment system, variable realtor as solar light/ or UV lamp according to climate condition such as sunny and cloudy days treated the phenol and E-coli(Escherichia coli) effectively.

• KIEE International Transactions on Power Engineering
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• 제11A권4호
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• pp.45-50
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• 2001

The impact evaluation of a DSM program is a very important issue since the results are used to determine the sustainability of a program. In general. to estimate the impacts of a DSM program it is required to measure the electricity usage changes before and after a program. Since the measurement-based approaches cost highly, most of the conventional evaluations are based on the average figures. However estimation of the average-based impacts can lead to both distorted results of over/under estimation of kW and kWh savings and non-optimal DSM planning. In this paper, we have developed a new multi-point measurement approach which can evaluate kW and kWh savings of a DSM program more exactly. To do this, the saving rate and operating rate are defined and set as the function of load factor of a customer, and these rates are incorporated with the conventional diffusion function of Bass to project the future impacts of a DSM program. The case study is performed on the inverter program of Korea by using the suggested approach.

• 한국지열·수열에너지학회논문집
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• 제17권2호
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• pp.20-29
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• 2021

In this study, it is proposed that an analysis method using charatersistics curve of PICV in the CFD simulation for hydronic system. From the results, the pressure drop characteristics appeared in the region of PICV at a specified flow rate. And the CFD results are in good agreement with the experimental results. Proposed analysis method is proved that the characteristics of PICV applied to the hydronic system were properly applied in the flow analysis. This result can be applied to PICV in the complex hydronic systems. Therefore, the optimal selection of PICV in hydronic system contribute the building energy saving.