• KIEAE Journal
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• v.14 no.1
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• pp.75-81
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• 2014

This study aims at investigating the benefit of actively controlling humidity to improve thermal comfort and energy efficiency in climate zones other than hot-dry. For this research purpose, three thermal control strategies, which adopted different initiative degrees in humidity control, were developed - i) temperature controls, ii) temperature and humidity controls, and iii) thermal sensation controls. Performance of the developed strategies were experimentally tested in a full scale mock up of an office environment. The study revealed that air temperature was better controlled in the occupied zone under the first two strategies than the thermal sensation based strategy. On the other hand, the thermal sensation-based strategy maintained thermal sensation levels more comfortably. In addition, energy consumption was significantly reduced when humidity was actively controlled for thermal comfort. The thermal sensation-based control strategy consumed significantly less electricity than the first two strategies. From these findings, this study indicated that adoption of an active humidity control system based on thermal sensation can provide increased thermal comfort as well as energy savings for summer seasons in climatic zones other than hot-dry.

• Journal of the Semiconductor & Display Technology
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• v.10 no.2
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• pp.13-17
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• 2011

We have developed a new energy-consuming monitoring system that has made it possible to measure the energy consumption of a gas scrubber, one of semiconductor processing equipments, and installed this system to the gas scrubber under operating at a manufacture site. Using this system, we have measured consumptions of electric power and processing gas consumed at standby to operating mode. In case of the gas scrubber, processing gas flows continuously into it at standby and operating mode. Therefore, if the electric power has been supplied, the processing gas can flows into the device for 24 hours. Moreover, at operating of gas scrubber, the amount of electricity consumption is 5 kWh. At Standby of gas scrubber, it spends 3kwh. It is certain that the energy consumption is greater at operating mode than at standby mode. The carbon emission rates from 24 hour gas scrubber operation are 236 $kgCO_2$/day of $N_2$, 57 $kgCO_2$/day of electric power and 0.001 $kgCO_2$/day of cooling water. Most of carbon is emitted from $N_2$ gas and electric power consumption.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.654-661
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• 2008

Our government will make a plan regulating the cooling limit temperature of the summer season to 26 degree and the heating limit temperature of the winter season to 20 degree for energy saving. Where, the key point of this politic pursuit can be the charge system on heating and cooling cost. Currently, the heating and cooling cost are charged as much as the volume or heat flow rate regardless of the high and low room temperature. However, we have suggested new cost estimating methodology as a worth method in the precedent study, and preformed the worth evaluation and cost allocation of electricity and heat on various cogenerations. In this study, we applied the suggested worth method to four kind of warm air, and preformed the worth evaluation and cost allocation of each warm air. As a result, the more energy a customer saved, the more heating unit cost decreased, and the more energy a customer consumed, the more heating unit cost increased. From this analysis, we hope that the suggested worth methodology can offer a theoretical basis to the politic pursuit of government, and induce the spontaneous energy saving of consumers.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.3
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• pp.52-65
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• 2021

A large amount of time and cost is consumed due to congestions caused by an increasing number of cars which results in a lot of emissions. To overcome these problems, a new electric vertical takeoff and landing (eVTOL) aircraft is being considered. Since vertical take off and landing without a separate runway is realized and electricity is used as a power source, it could solve the saturated ground traffic congestions without emissions. In this paper, the initial sizing was performed based on the Nexus 6HX of Belltextron which is a tilt-ducted fan type. In this study, the electric propulsion system that only uses battery was implemented instead of current Nexus 6HX hybrid electric propulsion. Aerodynamic analyses were performed using OpenVSP and XFLR5. Power-to-weight ratio, wing loading, estimated weight were calculated with these analyses.

• Journal of Biosystems Engineering
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• v.7 no.2
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• pp.72-85
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• 1983

Rice whitening is performed by basically two different whitening actions known as abrasive and frictional. The former adopted in the emery stone abrasive type whiteners and the latter in the jet-air friction type. Comparative milling yields and whitening efficiencies between the whitening system consisting of jet-air friction type whiteners only and the system consisting of both abrasive- and jet-air friction-types have not yet been rigorously defined. This study was to examine the effect of combined operations of abrasive- and jet-air friction-type rice whiteners on milling yields and whitening efficiencies. The small capacity commercial units of the abrasive- and friction-type whiteners were used for the experiments. The combinations of whitening treatments were: 1) Once in the abrasive type and then two to three times in the friction type, 2) twice in the abrasive and then two to three times in the friction type and 3) three to five times in friction type. In these tests, counter pressures for the friction type whiteners were established differently as required to get about the same degree of whitening at the end of predetermined numbers of the repeated operations. The speed of emery stone and the slot angle of the screen were also the factors varied in the abrasive type whitener. Sheukwang rice variety having 13.05% M.C. was used in the tests. The dependent variables were the milled- and head-rice recoveries and electricity consumption. The results of the study are summarized as follows: 1. It was found that in the whitening systems consisting of abrasive- and friction-type whiteners slot angle of the screen, the rotational speed of emery stone roller had significant effect on the milling yields and whitening efficiency. In general, the increase of the emery stone roller speed from 690 to 950 rpm presented a positive effect on milling yield, and one-pass abrasive milling combinations had higher milling yields than two-pass abrasive milling combinations. 2. It was apparent that if the slot angle of the screen and the speed of emery stone roller are modified and set at an optimum level, the combination whitening system consisting of abrasive- and friction-type whiteners is better than the pure frictional whitening system consisting of jet-air friction type in terms of milling yields and efficiencies. 3. In the rice whitening system consisting of abrasive- and jet-air friction-type whiteners, the best whitening performance was obtained when the slot angle of the screen and the rotational speed of emery stone roller were $45^{\circ}$ and 950rpm, respectively, for the one-pass abrasive milling combinations. However, for the two-pass abrasive mi11ing combinations, the best performance was obtained with $75^{\circ}$ of slot angle and 950 rpm of the emery stone roller speed. 4. As compared with pure frictional whitening systems, the combination systems produced more milled rice by 0.8-1.0% point and more head rice by 0.5-1.5% point, and consumed less electricity by 0.15-0.20 KwH per 100kg of milled rice when the abrasive whiteners were operated in the modified conditions as described in item 3 above. Further study is recommended to find out optimum operational and design conditions of abrasive type whiterners.

• Land and Housing Review
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• v.12 no.3
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• pp.79-85
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• 2021

This study analyzed the energy consumption differences between rental and owner owned (purchased) apartments in Busan, South Korea during the cooling and heating seasons. Analysis revealed that the average electricity consumed for cooling was 2.5 kWh/m²·yr for rental apartments and 2.3 kWh/m²·yr for purchased apartments, a difference of 0.2 kWh/m²·yr. The average electrical heating energy consumption was 3.3 kWh/m²·yr for rental apartments and 2.2 kWh/m²·yr for purchased apartments, a difference of 1.1 kWh/m²·yr. It was estimated that the use of electric blankets and heaters was higher in rental apartments than purchased apartments resulting in higher electrical heating energy consumption. The average gas heating energy consumption was 7.0 kWh/m²·month for rental apartments and 6.8 kWh/m²·month for purchased apartments. When electricity and gas usage was combined for heating, the average total heating energy consumption was 10.3 kWh/m²·month for rental apartments and 9.0 kWh/m²·month for purchased apartments. This indicates that rental apartments consume 1.3 kWh/m²·month more energy than purchased apartments during heating season. Overall, rental apartments consume more energy than purchased apartments during both the cooling and heating seasons.

• Journal of IKEEE
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• v.18 no.3
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• pp.335-340
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• 2014

Recently, LED (Light Emitting Diode) becomes to be useful to apply for the lightening sources in electric systems and the lightening equipment since the power is less consumed with high efficiency, and the size and the weight of LED are small and light, respectively. The LED is controlled with constant current and SMPS (Switching Mode Power Supply). It is necessary for the LED manufacturer to secure the fundamental technology of designing LED chip, and to study the methodology to improve the power factor (PF) and to design the operational circuit for the development of LED to reduce the power loss in the application of LED lightening. The direct AC (Alternating Current) LED driving circuit, HV9910, is widely used in the industry field. In this paper, it is to evaluate the improved methodology for the power factor and efficiency through simulations when PFC (Power Factor Correction) and Noise Filter are added to HV9910.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.31-42
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• 2017

Many studies have been performed to reduce electric consumption in railway systems. Due to its low conduction loss and high regenerative braking efficiency characteristics, the ESS powered railway system is chosen as a promising candidate for future railway systems. This paper introduces the ESS powered railway system and analyzes current power charge calculation methods that have been set up by KEPCO (Korea Electric Power Corporation). Based on the analysis, this paper proposes two different power charge reduction methods for the railway system. One is to smooth the peaks of traction energy consumption by supplying additional energy to the grid. The other is to save electric charge by reducing electric energy consumed by the railway during the energy peak time, 2 p.m.~5 p.m., which has highest 'Won/kWh' rates. To verify the effectiveness of the proposed method, the power charge of Seoul Metro Line 2 is recalculated using the method.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.115-120
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• 2009

The studies for mechanical performance development have been examined to reduce energy consumption in building construction field. However, The energy consumption using in building for heating is impacted by not only system performance but also PMV particularly at temperature and clo. Most energy using in building part is mainly consumed for heating and cooling to keep comfort temperature. Heating energy consumption is bigger than cooling energy in Korea because of temperature difference in winter in comparison with summer at apartment building. This means that energy consumption can be changed by occupancy's comfort setting temperature in apartment building. This study evaluate actual comfort temperature range by clo and examined heating energy consumption by Esp-r and CO2 reduction possibility. The results show that keeping ASHRAE standards can reduce heating energy up to 23%; also, wearing underclothes with ASHRAE standard can reduce heating energy up to 47.8%. Option 4 showing Maximum CO2 emission reduction indicates that kerosene. LNG and electricity can reduce 1.5t, 1.7t, 2.46t respectively in comparison with option 2.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.1
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• pp.109-120
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• 2013

In this paper we proposed the design of the hybrid road lighting control system using solar-light generation. The proposed hybrid road lighting control system be power offer through hybrid controller using Solar-Light Generation, and it is designed so that it can control lighting up. To control supply of continuous power when during power shortages. And the gateway be transmit control command using zigbee to road lighting to ensure that automatic lighting control on human sensing. In this case, the gateway is apply the lighting control algorithm that decisions to the status of the system by a pre-set time schedule and be able to operate. In this paper, the proposed efficiency analysis results of a hybrid road lighting control system was consumed power of 129.6W per day, 3.8KW per month, 47.3KW per annual. As a result, it were able to increase the energy efficiency than existing lighting control system by reduce power consumption of 76.2% and the electricity prices of 76.8%.