• Particle and aerosol research
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• v.17 no.2
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• pp.29-36
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• 2021

In this study, the clean air delivery rate (CADR) of ceiling air circulator (CAA) was determined under indoor environmental simulation conditions. An air filter was used to provide air cleaning ability to the CAA. The CADR of filter adapted CAA was evaluated and compared with the value of commercial air purifier. The installation of mesh-shaped filter on the CAA showed particle reduction effect on the particles over 0.4 ㎛ in diameter, but the CADR was up to 0.25 m³/min. When the filter having 99.9% in collection efficiency was installed on the CAA, its CADR was 1.52 m³/min, while the CADR of commercial air purifier was 3.19 m³/min.

• Particle and aerosol research
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• v.9 no.3
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• pp.139-147
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• 2013

The performances of indoor air cleaners including particle cleaning capacity and collection efficiency are usually tested at the condition of the maximum air flow rate of the air cleaners. However, the power consumption of the air cleaners is highly dependent on the air flow rate of the individual air cleaners. Therefore, there seems to be an optimized air flow rate for the air cleaning capacity considering power consumption. In this study, clean air delivery rate(or standard useful area as suggested room size) and power consumption have been investigated for different maximum air flow rates of 15 air cleaners and then compared those for different air flow rate modes of the individual 5 air cleaners selected from the 15 cleaners. For the maximum air flow rate conditions of 15 air cleansers, the power consumption per unit area was less related to the maximum air flow rate. However, for the different air flow rate modes of the selected 5 air cleaners, the lower power consumption per unit area was corresponding to the lower air flow rate mode of the individual air cleaners. When considering the operation time to the desired particle concentrations, there was an optimized one in the medium air flow rate modes for the individual air cleaners. Therefore, not only the maximum air flow rate but also lower air flow rates of individual air cleaners should be considered for estimating air cleaning capacity based on energy consumption per unit area.

• Journal of Pharmaceutical Investigation
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• v.41 no.6
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• pp.347-354
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• 2011

Repeated oral administration of loxoprofen can induce many side effects such as gastric disturbances and acidosis. Therefore, we considered alternative routes of administration for loxoprofen to avoid such adverse effects. The aim of this study was to develop an ethylene-vinyl acetate (EVA) matrix system containing a permeation enhancer for enhanced transdermal delivery of loxoprofen. The EVA matrix containing loxoprofen was fabricated and the effects of drug concentration, temperature, enhancer and plasticizer on drug release were studied from the loxoprofen-EVA matrix. The solubility of loxoprofen was highest at 40% (v/v) PEG 400. The release rate of drug from drug-EVA matrix increased with increased loading dose and temperature. The release rate was proportional to the square root of loading dose. The activation energy (Ea), which was measured from the slope of log P versus 1000/T, was 5.67 kcal/mol for a 2.0% loaded drug dose from the EVA matrix. Among the plasticizer used, diethyl phthalate showed the highest release rate of loxoprofen. Among the enhancers used, polyoxyethylene 2-oleyl ether showed the greatest enhancing effect. In conclusion, for the enhanced controlled transdermal delivery of loxoprofen, the application of the EVA matrix containing plasticizer and penetration enhancer could be useful in the development of a controlled drug delivery system.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.6
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• pp.67-79
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• 1997

The perpose of this study was to suggest the experimental characteristic of the Cherepnov Water Lifter following the drain mode. The Cherepnov Water Lifter(CWL), which is powered by the potential energy of water, can be set to operate automatically when the water m a tank is drained. In this study, a CWL is constructed in the valve drain controlling mode(VCM) and the siphon drain controlling mode(SCM), and a pressure transducer is installed. It was found that, in the VCM, intake flow volume is proportional to both delivery flow volume and drain flow volume. In the SCM, intake flow volume is proportional to drain flow volume, and the average delivery rate is proportional to both efficiency and the water utilization ratio. Also, in the VCM, the water utilization ratio is 35~49%, efficiency is 62~9O%, average delivery rate is 12.8~81.2$cm^3$/s, and the average drain rate is 14.O~91.5c$cm^3$/s. On the contrary in the SCM, the water utilization ratio is 1.7~38%, efficiency is 3~58%, average delivery rate is 3.1 ~69.2$cm^3$/s, and the average drain rate is shown as 114.5~ 183$cm^3$/s. As a result of the water utilization ratio, efficiency, average delivery rate, and average drain rate are compared, the VCM is found to be superior and the more economical mode. However, the VCM requires manpower and electricity to operate the electronic machinery involved, while the SCM requires no manpower or electricity at all. An economic evaluation of these differences will be necessary in the future. Also, in the SCM, studies to improve water utilization ratio and efficiency, to find the optimum height of the siphon for decreasing the average drain rate, and to determine the radius of curvature of throat have to be conducted in advance, since a large flow rate is drained during the priming action of the siphon.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.372-379
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• 2011

A nuclear fusion fuel cycle plant is composed of various subsystems such as a hydrogen isotope storage and delivery system, a tokamak exhaust processing system, and a hydrogen isotope separation system. Korea shares in the construction of its ITER fuel cycle plant with the EU, Japan, and the US, and is responsible for the development and supply of the storage and delivery system. The authors thus present details on the development status of hydrogen isotope storage technologies for nuclear fusion fuel cycle plants. We have developed various hydride beds of different size. We have realized a hydrogen delivery rate of 12.5 $Pam^3/s$ with a typical 1242g-ZrCo bed.

• Journal of Environmental Science International
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• v.12 no.12
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• pp.1235-1243
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• 2003

Under controlled conditions in an environmental chamber, 24 experiments were performed to compare the ability of a Variable-Air-Volume/Bypass Filtration System(VAV/BPFS) to remove indoor pollutants and to conserve energy with the ability of conventional Variable Air Volume(VAV) system. The specific conclusions of this paper were; first, the VAV/BPFS was more efficient than the VAV system in removing particulate matter, TVOC, and target VOCs. The total effective removal rate of PM for the VAV/BPFS was two times as high as that of the VAV system. The total effective removal rate of TVOC for the VAV/BPFS was 20 percent higher than that of the VAV system. Also each target VOC concentration was reduced by using the VAV/BPFS. Second, clean air delivery rate was increased by using VAV/BPFS due to additional filtration rate. Otherwise, the VAV/BPFS decreased outdoor supply air rate above 25 percent relative to the rate of VAV system. Third, total energy consumption by the VAV/BPFS was lower than that of the VAV system during the period with indoor thermal load, occupied time. The energy saving of the VAV/BPFS ranged from 11 to 16 percent. The VAV/BPFS improves indoor air quality more efficiently than the VAV system, and it reduced energy consumption. Retrofitting the VAV system with the VAV/BPFS was easy The use of VAV/BPFS is, therefore, recommended far buildings with VAV system as well as for buildings at designing stage.

• Smart Media Journal
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• v.13 no.1
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• pp.45-51
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• 2024

Long Range Wide Area Network (LoRaWAN) is a widely adopted Internet of Things (IoT) protocol due to its high range and lower energy consumption. LoRaWAN utilizes Adaptive Data Rate (ADR) for efficient resource (e.g., spreading factor and transmission power) management. The ADR manages these two resource parameters on the network server side and end device side. This paper focuses on analyzing the ADR and Gaussian ADR performance of LoRaWAN. We have performed NS3 simulation under a static scenario by varying the antenna height. The simulation results showed that antenna height has a significant impact on the packet delivery ratio. Higher antenna height (e.g., 50 m) has shown an improved packet success ratio when compared with lower antenna height (e.g., 10 m) in static and mobility scenarios. Based on the results, it is suggested to use the antenna at higher allevation for successful packet delivery.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.214-220
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• 1998

We have studied the factors influencing the growth rate of TiN deposited from TDEAT using a bubbler. The growth rate of TiN was primarily dependent on the bubbler temperature, deposition temperature, gas delivery line conductance and carrier gases. In addition, the heating of the gas line through which carrier gas was delivered to the bubbler increased the growth rate slightly. Also heating of the delivery gas line between the bubbler and the chamber caused the increase of the growth rate of TiN, Showing the Arrehenius behaviour with the activation energy of 0.2 eV.

• Particle and aerosol research
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• v.14 no.1
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• pp.9-16
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• 2018

We have developed an electrostatic precipitation (ESP) type air cleaner for indoor air quality and investigated its performances regarding CADR (Clean air delivery rate), single-pass efficiency and gas removal efficiency. The ESP air cleaner used an ACF (Activated carbon fiber) filter for gas removal and the ACF as a high voltage electrode for particle removal. The ESP air cleaner was tested in a chamber with the volume of $1m^3$ regarding CADR and gas removal efficiency. The applied CADR area of the ESP was $1.8m^2$. Gas removal efficiency was tested with 3 gases (Acetaldehyde, Acetic acid, Ammonia). As the results of the gas removal efficiency, the ESP air cleaner shows the removal efficiencies of 90, 98 and 85% for acetaldehyde, acetic acid and ammonia, respectively.

• Particle and aerosol research
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• v.13 no.1
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• pp.17-23
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• 2017

In this study, the test results obtained from the performance tests for CA (Korea Association of Cleaning Air) certificated air cleaners which had been commercially available in Korea from 2003 to 2015 were analyzed. Among the test parameters such as flow rate, particle collection efficiency, clean air delivery rate (CADR), ozone emission, odor removal efficiency and noise level, noise level and CADR were correlated with flow rates. Collection and odor removal efficiencies were 20% higher than the limit of the CA certification. The ozone emissions from the air cleaners were negligible because all the air cleaners were equipped with only HEPA filters, not electrostatic precipitation method which produces ozone.