• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.385-393
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• 2013

In this paper, the mechanism identification and the avoidance measures on the phenomena of transient acoustic vibration amplified at the water-supply piping system to regulate the steam temperature of the boiler reheater in 500MW class supercritical power plant are presented. The pressure pulsation waves induced by the impeller passing of two feed-water pumps with five blades are coincident with the local acoustic modes of boiler reheater water-supply piping system. There are the phenomena amplified at the peaks of 5X, 10X, 15X and 20X in spectrums of piping vibration, sound pressure, and the feed-water's pressure pulsation waves. The shut-off device is installed in the piping system for the interception of pressure pulsation waves transmitted from two feed-water pumps and the modified design change of the piping layout is applied for the acoustic resonance avoidance. The acoustic natural frequencies are separated from the harmonics of pressure pulsation waves induced by the pump impellers passing through the design change of the span length. The acoustic vibration is gone by resonance avoidance measures. As a result, more than 20 dBA reduction is achieved from 100 dBA to 80 dBA.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.261-269
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• 2015

In this study, we applied a membrane distillation process to investigate a feasibility of treating a wastewater with high concentration of organic matters including nitrogen and phosphorus. The laboratory scale experiment was performed by using a hydrophobic PVDF membrane with the pore size of $0.22{\mu}m$ and porosity of 75%. The installation was direct contact type where the temperature difference between a feed and permeate side was controlled to have a range from 20 to $60^{\circ}C$. We observed a flux variation and a concentration changes of COD, $PO{_4}^{3-}$-P, $NH_4{^+}$-N and conductivity of feed side as well as permeate side with various temperature differences (20 to $60^{\circ}C$), cross flow velocities (0.09 to 0.27 m/s) through the module, and pH (6.6 to 12.0) of the feed that has the initial concentration of COD about 1,000 mg/L, total nitrogen 390 mg/L, total phosphorus 10 mg/L, conductivity of $7,000{\mu}s/cm$. The results showed that the average flux was ranged from 4 to $40L/m^2/hr$ which was almost similar with the flux of NaCl and deionized water used as a feed solution. The lowest flux was obtained at the operating condition with the temperature difference of $20^{\circ}C$ and cross flow velocity of 0.09 m/s while the highest one was measured with $60^{\circ}C$ and 0.27 m/s. Above 99% of COD and $PO{_4}^{3-}$-P in the feed could be rejected regardless of an operating condition. However, the removal rate of ammonium nitrogen was varied from 64 to 99% depending on the pH of feed solution.

• Membrane and Water Treatment
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• v.3 no.4
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• pp.243-252
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• 2012

Tri-n-butyl phosphate (TBP) was used as carrier for the transport of Golden yellow and Cibacron LSG dyes through a hexane bulk liquid membrane. The transport efficiency of dyes by TBP was investigated under various experimental conditions such as pH of the feed phase (dyes solution), concentration of the receiving phase (NaOH solution), concentration of TBP in membrane, rate of stirring, effect of transport time, type of solvent, dye concentration in feed phase, effect of temperature.. The maximum transport dyes occurs at ratio of 1:1 TBP-hexane At pH 3.0 0.1 (feed phase) the transport dyes decreased. At high stirring speed (300 rpm) the dyes transport from the feed phase to the strip phase was completed within 60 minutes at $27^{\circ}C$. Under optimum conditions: Feed phase 100 mg/L dyes solution at pH 1.0 0.1, receiving phase 0.1 mol/L NaOH solution, membrane phase 1:1 TBP-hexane , Stirring speed 300 rpm and temperature $27^{\circ}C$, the proposed liquid membrane was applied to recover the textile effluent.

• Membrane and Water Treatment
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• v.8 no.6
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• pp.529-541
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• 2017

A multi-effect air gap membrane distillation (ME-AGMD) module for pesticide wastewater treatment is studied with internal heat recovery, sensible heat of brine recovery, number of stages and the use of fresh feed as cooling water in a single module is implemented in this study. A flat sheet polytetrafluroethylene (PTFE) membrane was used in the 4-stage ME-AGMD module. The maximum value of permeate flux could reach $38.62L/m^2h$ at feed -coolant water temperature difference about $52^{\circ}C$. The performance parameter of the module like, specific energy consumption and gain output ratio (GOR) was investigated for the module with and without heat recovery. Also, the module performance was characterized with respect to the separation efficiency of several important water quality parameters. The removal efficiency of the module was found to be >98.8% irrespective water quality parameters. During the experiment the membrane fouling was caused due to the deposition of the salt/crystal on the membrane surface. The membrane fouling was controlled by membrane module washing cycle 9 h and also by acidification of the feed water (pH=4) using 0.1M HCl solution.

• Journal of the Korean Wood Science and Technology
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• v.50 no.1
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• pp.59-67
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• 2022

Dietary fiber is considered a feed ingredient with high nutritional value in the broiler feed industry. Pine chips contain a large amount of dietary fiber and require some modification for use as broiler feed. In this study, pine chips were subjected to steam explosion under different severity factor (Ro) conditions to improve the chemical and physical properties of dietary fiber. The highest water-holding capacity, oil-holding capacity, and swelling capacity were found for Ro 4.0, followed by Ro4.5 and 3.5. The optimal condition for the steam explosion was determined to be Ro 4.0 (reaction temperature of 210℃, and reaction time of 6.0 min). Under these conditions, the water-holding capacity, oil-holding capacity, and swelling capacity of steam-exploded pine chips were 8.3 g/g, 6.5 g/g, and 5.0 mL/g, respectively. This study may contribute to the application of lignocellulose and related products in the broiler feed industry.

• Journal of Biosystems Engineering
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• v.30 no.1 s.108
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• pp.8-16
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• 2005

The extrusion-cooking condition on Cordyceps pruinosa was designed using twin-screw extruder. Response surface methodology (RSM) was used to investigate extrusion-cooking using a central composition design with varying die temperature $(114-146^{\circ}C)$, feed moisture $(22-38\%)$, feed rate (4-14 ka/h) and screw speed (120-280 rpm). System parameters (die pressure and specific mechanical energy (SME)) and extrudate parameters (density and water solubility index (WSI)) were statically analyzed using RSH. Die pressure was significantly affected by temperature, moisture contents and feed rate. SM was affected by screw speed and feed rate. When die temperature is $130^{\circ}C$ and moisture content $25\%$, the optimum pressure is shown. SME is about 20 Wh/kg, when feed rate is $10\~12kg/min$ and screw speed $200\~250rpm$. WSI was affected by temperature and moisture contents. Density was not affected by any factor. WSI increases by $7\%$ from about $23\%$ to about $30\%$, as temperature is raised from $120^{\circ}C\;to\;140^{\circ}C$. The WSI of Cordyceps pruinosa pulverized after extruding (PE) is about $26.97\%$ higher than that of raw material and $10\%$ higher than that of pulverized after drying (PD). The content of unsaturated fatty acid were not significantly different in PD and PE. Anti-oxidative activity of PE was 1.67-2.2 times higher than that of PD in Cordyceps pruinosa using 1- dipheny1-2-picrylhydrazyl method (DPPH).

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.414.1-414
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• 2002

• Membrane Journal
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• v.13 no.4
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• pp.257-267
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• 2003

For the treatment of reactive phenolic resin waste, a simulation model of pervaporative dehydration process has been developed through hollow fiber membrane module. Some of basic parameters were determined directly from dehydration of the waste liquid through a flat sheet membrane to get realistic values. The simulation model was verified by comparing the simulated values with experimental data obtained from hollow fiber membrane module. Hollow fiber membranes with active layer coated on inside fiber were used, and feed flew through inside hollow fiber. Feed flow rate affected membrane performances and reaction by providing a corresponding temperature distribution of feed along with fiber length. Feed temperature is also a crucial factor to determine dehydration and reaction behavior by two competing ways; increasing temperature increases permeation rate as well as water formation rate. Once the permeate pressure is well below the saturated vapor pressure of feed, permeate pressure had a slightly negative effect on permeation performance by slightly reducing driving force. As the pressure approached the vapor pressure of feed, dehydration performances declined considerably due to the activity ratio of feed and permeate.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.319-323
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• 2008

Mutant rice cv. Goami2 (G2) and Baegjinjoo (BJJ) derived from a high-quality japonica rice cv. Ilpumbyeo (IP) were extruded under different feed moisture (20 and 30%) and barrel temperature (90, 110, and $130^{\circ}C$). Increasing feed moisture at fixed barrel temperature increased extrudate density (ED) in IP and BJJ. Whereas, G2 showed a varied ED depending on extrusion conditions; increasing barrel temperature decreased the ED of G2 extrudate with low feed moisture, but increased with high moisture. Results indicated a positive barrcl temperature effect on volume expansion in IP and G2, but a negative effect on 811, probably due to shrinkage of expanded products containing low-amylose contents. A significant increase of water absorption was found in G2 and BJJ extruded flour, while an increase of water solubility in those from IP. Non-digestible carbohydrates measured by total dietary fiber (TDF) indicated that extrusion increased slightly TDF in IP and BJJ extrudates, but decreased in G2 products, which might be variety-dependent.

• Membrane Journal
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• v.23 no.5
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• pp.360-366
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• 2013

The Poly (vinylidene fluoride) and poly (acrylonitrile) (PAN) hollow fiber composite membranes coated with poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) as the crosslinkig agent are prepared. The resulting membranes were characterized for aqueous 90 wt% ethanol solution by pervaporation techniques in terms of the permeability and separation factor. In general, as both the crsslinking reaction temperature and the crosslinking agent concentration increase, the permeability decrease while the separation factor tends to increase. And also the permeability increased and the separation factor decreased as the feed temperature increased. Typically, the permeability $502g/m^2hr$ at the feed temperature $70^{\circ}C$ was obtained for PVDF hollow fiber membrane prepared with the crosslinking agent PAA 3 wt% at the reaction temperature $60^{\circ}C$ whereas the separation factor 218 was shown for the membrane reacted with PAA 11 wt% and at $100^{\circ}C$ for the feed temperature $50^{\circ}C$.