• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.7
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• pp.630-638
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• 2004

Liquid desiccant dehumidification systems have the ability to provide efficient humidity and temperature control while saving the electrical energy requirement for air conditioning as compared to a conventional system. The dehumidifier and the regenerator form the heart of this system. The latent part of the cooling load is overcome using liquid desiccant. The model regenerator has been designed to study the absorption characteristic of the aqueous triethylene glycol (TEG) solution which is in the flow range from 20 to 50 LPM. Also, this system designed that was able to change the height of the regenerator and dehumidifier. Because the effect of performance have different result according the height. The effect of performance factors of the regenerator with inlet solution flow rate, air flow rate, solution concentration, solution temperature, brine temperature, air temperature and inlet air relative humidity have been analyzed. Data obtained are useful for design guidance and performance analysis of the hybrid air conditioning system.

• International Journal of Fluid Machinery and Systems
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• v.6 no.3
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• pp.160-169
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• 2013

Two-stage turbocharging is an important way to raise engine power density, to realize energy saving and emission reducing. At present, turbine matching of two-stage turbocharger is based on MAP of turbine. The matching method does not take the effect of turbines' interaction into consideration, assuming that flow at high pressure turbine outlet and low pressure turbine inlet is uniform. Actually, there is swirl flow at outlet of high pressure turbine, and the swirl flow will influence performance of low pressure turbine which influencing performance of engine further. Three-dimension models of turbines with two-stage turbocharger were built in this paper. Based on the turbine models, mechanism of swirl flow at high pressure turbine outlet influencing low pressure turbine performance was studied and a two-stage radial counter-rotation turbine system was raised. Mechanisms of the influence of counter-rotation turbine system acting on low-pressure turbine were studied using simulation method. The research result proved that in condition of small turbine flow rate corresponding to engine low-speed working condition, counter-rotation turbine system can effectively decrease the influence of swirl flow at high pressure turbine outlet imposing on low pressure turbine and increases efficiency of the low-pressure turbine, furthermore increases the low-speed performance of the engine.

• Korean Journal of Food Science and Technology
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• v.24 no.5
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• pp.428-439
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• 1992

Drying process in a fixed bed red pepper dryer was modeled and simulated. Drying efficiency describing the effectiveness of energy usage in red pepper drying was defined as a ratio of energy used for moisture evaporation to total energy consumption, and expressed in combination of measurable temperature variables. The efficiency was compared with real evaporative efficiency and tested in the simulated and experimental drying. An overall drying efficiency was derived, and analyzed for various control variables consisting of drying temperature, air recycle ratio and air flow rate. Optimal operation conditions of drying was then searched by Box's complex method by using it as an objective function. Carotenoids retention was simulated and put as a constraint of product quality in the optimization. The optimization results gave that two staged drying operation could improve the ding efficiency compared with single staged drying. As a technique for further energy saving automatic termination of drying appeared feasible by monitoring an exit air temperature from dryer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1399-1406
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• 2010

Customers can monitor electricity use in real time in smart grid(ICT is grafted onto current grid), so various beneficial services can be provided to customer. We did a qualitative survey, HV(Home Visit) and FGD(Focus Group Discussion), in order to derive customer's cognition of using electricity in home and values that customers consider significantly and a quantitative survey in order to know willingness to use. Customers consider electricity indispensible for using home appliances, want to use safely far from electromagnetic waves, short circuit and electronic shock. Also, customers want to save energy conveniently with no stress. Customers want 'a function', 'information', 'motivation' for energy saving, and 'electromagnetic waves cutting', 'to prevent electronic shock', 'to prevent short circuit' for safe electricity use. In this study, we derived 4 services - energy monitoring, standby power cutting, remote control, energy consulting - based on customer values and unmet needs, which is connected to home network that customers can monitor total and each appliance's electricity usage in real time and control home appliances. The willingness to use of services is over 60% and especially energy monitoring and standby power cutting service have high willingness to use rate, about 80%.

• Journal of Internet of Things and Convergence
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• v.7 no.3
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• pp.9-14
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• 2021

This paper discovers the energy loss factors through the insulation diagnosis of houses or buildings, and proposes directions for energy efficiency improvement. The energy efficiency factor of a building consists of insulation diagnosis, thermal bridge diagnosis, window diagnosis, airtight diagnosis, and equipment diagnosis. Among the residents and facilities in the energy welfare blind spot, an energy efficiency diagnosis was conducted for one senior citizen building located in Naju-si, Jeollanam-do, and energy efficiency diagnosis was conducted after insulation was installed. Energy measurement, diagnosis and analysis were performed using the IoT-based integrated wired/wireless energy diagnosis platform, Energy Finder. As a result of comparison, an overall energy saving rate of 16.38% was achieved. Annual heating energy consumption per unit area decreased from 333.51kWh before construction to 277.35kWh after construction, and annual cooling energy consumption per unit area decreased from 5.51kWh before construction to 5.22kWh after construction. The annual primary energy consumption per unit area decreased from 464.52kWh before construction to 403.69kWh after construction, and the annual energy cost was reduced from 3,063,307.14 won before construction to 2,641,072.49 won after construction. The additional improvement work is needed on the standards affecting energy efficiency other than insulation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.328-336
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• 2015

Currently, 22% of the total energy consumption of buildings in Korea is used for lighting. Light-shelves have garnered attention as a way to reduce consumption, but there are few studies on the types of curve and curvature, which limits the improvement of light-shelf performance and its design. This study constructed a test bed of actual residential types to evaluate the performance. Outcomes of light usage, according to variables of light-shelves, were used as indicators of performance evaluation. The results are as follows:1) Performance evaluation was conducted on flat-type light-shelves to verify performance of curvature-shelves, which are movable with a width of 200 mm, and the most ideal angle and specification per solar term are calculated. 2) The (-) shaped curvature contributed to a reduction in energy consumption and an improvement of evenness. 3) In case of light-shelves with (-) shaped curvature, an increased angle not exceeding $80^{\circ}$ of the arc contributed to an improvement of light penetration. 4) Appropriate specifications of curved light-shelves include movable types with widths of 200 mm, and angle ranges of $20^{\circ}{\sim}60^{\circ}$. 5) Light energy consumption of a movable light-shelf with curvature and width of 200 mm were reduced by 17% and 7.8% compared to a $0^{\circ}$ fixed and a movable light-shelf, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.5
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• pp.51-60
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• 2006

In order to examine the heat transfer characteristic of a soil warming system and effects of soil warming on the greenhouse heating load, control experiments were performed in two greenhouses covered with double polyethylene film. One treated the soil warming with an electric heat wire and the other treated a control. Inside and outside air temperature, soil temperature and heat flux, and heating energy consumption were measured under the set point of heating temperature of $5,\;10,\;15,\;and\;20^{\circ}C$, respectively. Soil temperatures in a soil warming treatment were observed $4.1\;to\;4.9^{\circ}C$ higher than a control. Heating energy consumptions decreased by 14.6 to 30.8% in a soil warming treatment. As the set point of heating temperature became lower, the rate of decrease in the heating energy consumptions increased. The percentage of soil heat flux in total heating load was -49.4 to 24.4% and as the set point of heating temperature became higher, the percentage increased. When the set point of heating temperature was low in a soil warming treatment, the soil heat flux load was minus value and it had an effect on reducing the heating load. Soil heat flux loads showed in proportion to the air temperature difference between the inside and outside of greenhouse but they showed big difference according to the soil warming treatment. So new model for estimation of the soil heat flux load should be introduced. Convective heat transfer coefficients were in proportion to the 1/3 power of temperature difference between the soil surface and the inside air. They were $3.41\;to\;12.42\;W/m^{2}^{\circ}C$ in their temperature difference of $0\;to\;10^{\circ}C$. Radiative heat loss from soil surface in greenhouse was about 66 to 130% of total heating load. To cut the radiation loss by the use of thermal curtains must be able to contribute for the energy saving in greenhouse.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.896-905
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• 2012

Recently, the application of the plastic material to automotive components and structures has steadily increased to satisfy demands on the saving of overall weight and the improvement of energy efficiency. The objective of this paper is to investigate the development of a bumper back-beam using a thermoplastic olefin (TPO). The bumper back-beam was designed to be manufactured from the injection molding process. In order to obtain a proper design of the bumper back-beam, three-dimensional finite element analyses were performed for various design alternatives. Stress-strain curves for different strain rates were measured by high speed tensile tests of the TPO to consider strain rate effects in the FEA. The influence of the sectional shape and the rib formation on the contact force-intrusion curves, the deflection and the energy absorption rate of the bumper back-beam was examined. From the results of the examination, a proper design of the bumper back-beam was acquired. The bumper back-beam consisting of TPO was fabricated from the injection moulding process and the vibration welding. Pendulum crash tests were carried out using the fabricated bumper back-beam. The results of the tests showed that the designed bumper back-beam can satisfy requirements of the federal motor vehicle safety standard (FMVSS). Through the comparison of the previously designed bumper back-beam with the newly designed bumper back beam, it was noted that the weight of the designed bumper back-beam is lighter than that of the previously designed bumper back beam by nearly 16 %. In addition, it was considered that the newly designed bumper back beam can improve recycling of the bumper back-beam.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.6
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• pp.67-77
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• 2017

Demands for housing has diversified recently due to low birth rate and the growth of aging population. Also, a share of idle houses and obsolete houses over 20 years old is gradually rising. Therefore, there is a need for a sustainable, environment-friendly improvement policy that is in line with a new housing paradigm and avoids full-scale new construction, such as a customized housing renovation plan considering local economic circumstances. Therefore, afforestation system applicable to buildings are assessed positively, but lack objective performance evaluation. Through one-year, long-term monitoring of replicated obsolete buildings that have poor insulation performance, this study calculated monthly average power consumption and analyzed power charges by applying pricing plans before and after the revision of progressive tax in order to examine economic effects expected by applying the afforestation system. In the obsolete buildings, the study showed that monthly average power consumption was reduced by 16.6kWh with 5.2% average reduction rate. Highest reduction was made in July at 11.3%. Aggregate monthly power consumption charges were relatively high in winter before and after the revision of progressive tax. Power charges reduction effect was highest in March when monthly power consumption was reduced to 300kWh level by applying the afforestation system.

• Fire Science and Engineering
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• v.29 no.1
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• pp.60-66
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• 2015

The present study was aimed to analyze enclosure integrity test, which is the performance experiment of soaking time, in a fire zone equipped with gaseous extinguishing system in an effort to find understand the effect of precaution factors upon the success of fire extinguishment. To achieve the goal of this study, it divided the fire zones of internal and external power plants into ones taking precaution measures and not taking them and then enclosure integrity test was given respectively. Therefore, this study examined the success rate if the test according to the presence and absence of the precaution measure and confirmed the failure factors, designed concentration soaking time and proportion of leakage area to total volume area by type of gaseous extinguishing system and rooms. Precaution measures were applied to the fire zones without them to confirm the increase of the success rate of enclosure integrity test. By doing so, it was found that reduced number of experiments caused by failure led to cost saving.