• The KSFM Journal of Fluid Machinery
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• v.6 no.3 s.20
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• pp.58-63
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• 2003

The performance of turbo pump drops rapidly and it gets into break-down when the void fraction reaches above the threshold value because the impeller flow passage is choked up with air bubbles. Phenomenological understanding of break-down and pumping recovery mechanisms under air-water two-phase flow conditions are therefore important for pump designers and essential assignment for researchers. In this paper, we investigated the characteristics of break-down and pumping recovery due to entrained air occurring inside a screw-type centrifugal pump which has a wide flow passage mainly through the findings of suction and discharge pressures, rotational speed, flow rate measurements and visualization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.4
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• pp.1006-1025
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• 2012

Improving the quality of service in IP networks is a major challenge for real-time voice communications. In particular, packet arrival-delay variation, so-called "jitter," is one of the main factors that degrade the quality of voice in mobile devices with the voice-over Internet protocol (VoIP). To resolve this issue, a receiver-based enhanced timing recovery algorithm combined with active jitter estimation is proposed. The proposed algorithm copes with the effect of transmission jitter by expanding or compressing each packet according to the predicted network delay and variations. Additionally, the active network jitter estimation incorporates rapid detection of delay spikes and reacts to changes in network conditions. Extensive simulations have shown that the proposed algorithm delivers high voice quality by pursuing an optimal trade-off between average buffering delay and packet loss rate.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.845-850
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• 2009

Bioethanol derived from lignocellulosic biomass has the potential to replace gasoline. Cellulose is naturally recalcitrant to enzymatic attack, and it also surrounded by the matrix of xylan and lignin, which enhances the recalcitrance. Therefore, lignocellulosic materials must be pretreated to make the cellulose easily degraded into sugars and further fermented to ethanol. In this work, hydrothermal pretreatment on corn stover at $195^{\circ}C$ for 15 min with and without lower concentration of formic acid was compared in terms of sugar recoveries and ethanol fermentation. For pretreatment with formic acid, the overall glucan recovery was 89% and pretreatment without formic acid yielded the recovery of 94%. Compared with glucan, xylan was more sensitive to the pretreatment condition. The lowest xylan recovery of 55% was obtained after pretreatment with formic acid and the highest of 75% found following pretreatment without formic acid. Toxicity tests of liquor parts showed that there were no inhibitions found for both pretreatment conditions. After simultaneous saccharification and fermentation (SSF) of the pretreated corn stover with Baker's yeast, the highest ethanol yield of 76.5% of the theoretical was observed from corn stover pretreated at $195^{\circ}C$ for 15 min with formic acid.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.293-299
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• 2023

UPRT(Upset Prevention And Recovery Training) is an accident prevention training program developed over a three-year period after the main cause of aircraft accidents in commercial aviation between 2001 and 2011 was analyzed as LOC-I(Loss Of Control Flight). In 2014, ICAO presented UPRT for fixed-wing aircraft through Doc.10011(Manual On Aeroplane Upset Prevention And Recovery Training) and recommended mandatory implementation to Contracting States from March 2019. Since naval P-3C is a major mission of maritime patrol and anti-submarine warfare, it takes a lot of time to fly at low altitude (70-600 m), and the majority of P-3C pilots have experienced spatial disorientation, so Upset prevention and recovery training is essential for naval P-3C pilots. To this end, this study intends to present measures for UPRT from limited conditions using the P-3C simulator owned by the Navy.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.331-336
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• 2016

In this study the optimum conditions for recovery of valuable metal in Electric Arc Furnace Dusts were investigated. 2M of $H_2SO_4$, 1~5 of solid/liquid ratio, 0~180 min of leaching time has been established for leaching condition, and for electrowinning, each of Pt, C, Zn, Pb anode and Zn, Cu cathode was compared respectively at pH 2, 4 and 6. The result of elemental analysis of Zn crystal, a lagre quantity of Fe and H has been observed with Zn and other heavy metal, therefore, impurities removing process would be requir for enhancing purity of Zn. As the result, about 60% of Zn has been recovered under condition of 2 M of $H_2SO_4$, 1:2 of S/L ratio at 120 min, and Pt or Pb for anode, Zn for cathode has been shown the highest efficiency of electrowinning at pH 6.

• Journal of the Korean Society of Clothing and Textiles
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• v.13 no.3 s.31
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• pp.187-196
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• 1989

The purpose of this study is to find at the basic data for the appropriate compressibility of the pillows for the Koreans as well as, for the appropriate conditions to establish the estimating criterion for the pillows on the market place. This paper also aim to grasp thr compressibility of the materials used to make the pillows for sale. The appropriate compressive rate of the pillows have been investigated by sensuous test. The compressive rate, recovery rate, and decreasing rate of compression and recovery have been investigated by means of ergonomic and physical experiments. The results were as follows; 1) By sensuous test, the compressive rate of the pillows for the most comfortable state turns up $45\%{\pm}5\%$ in men and women. 2) As for the compressive rate and recovery rate of the eight pillow materials on market, panya, duck feather two kinds of synthetic fiber are highest, wood is lowest. 3) The compressive rate of panya, duck feather, and two kinds of fiber is within the range of the comfort by sensuous test. 4) In the durability of the compressive rate and recovery rate against the repeated use of the pillows, duck feather is in the highest grade, panya is the lowest grade and the others are graded between two.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• Journal of Marine Bioscience and Biotechnology
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• v.9 no.2
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• pp.35-42
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• 2017

Hydrothermal liquefaction of lipid-extracted Tetraselmis sp. feedstock containing 80 wt.% water was conducted in a batch reactor at different temperatures (300, 325, and $350^{\circ}C$) and reaction times (5, 10, 20, 40, and 60 min). The biocrude yield, elemental composition and higher heating value obtained at various reaction conditions were used to predict the optimum conditions for maximizing energy recovery of biocrude with good quality. A maximum energy recovery of 67.6% was obtained at $325^{\circ}C$ and 40 min with a high energy density of 31.8 MJ/kg and lower contents of nitrogen and oxygen. Results showed that reaction conditions of $325^{\circ}C$, 40 min was most suitable for maximizing energy recovery while at the same time achieving improved quality of biocrude.

• Journal of Wetlands Research
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• v.3 no.2
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• pp.119-131
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• 2001

This study uses HEC-RAS for the quantitative aspects and the QUAL2E model for the qualitative aspects of the flow of urban streams, where the natural recovery system is applied. The instream flow of the small streams is estimated using the numerical model by verifying the existing data with the acquired data. The characteristics of the model reach place more weight on the drought discharge around the ordinary discharge, and this is caused by the natural recovery system that maintains the existing bank. The data of direct discharge to the sewage treatment plant through the inception pipe, BOD, DO, temperature, and so forth, are the official data from the department of environment. Considering the characteristics of small streams, the factors for the QUAL2E model are estimated with the focus on the hydraulic conditions and the stream view. This study proposes the future improvements for the natural recovery system by investigating the practical use of the waterfront and the application of the proper instream flow. Also, the hydraulic and hydrological investigation of the covering rate by the natural vegetation and the meandering by the varying river way is performed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.956-964
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• 2005

In order to control indoor air quality and save energy, it is needed to install a suitable ventilation system equipped with heat exchanger for heat recovery The purpose of this research is to find the factors affecting the performance of paper heat exchanger for exhaust heat recovery, which can be applied directly to the conventional ventilation unit, air-purifier, and air-conditioning system. In this study, thermal performance and pressure loss of the paper heat exchanger are measured and compared at various operating conditions. The effectiveness of sensible, latent and total heat at the face velocity of 0.75 m/s are $77\%,\;47\%\;and\;57\%$ in the cooling condition and $77\%,\;59\%,\;and\;\%$ in the heating condition, respectively. The effectiveness for sensible heat is only affected by velocity. On the other hand, the effectiveness for latent heat is affected. by temperature and relative humidity.