• Journal of the Korea Furniture Society
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• v.15 no.2
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• pp.19-27
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• 2004

As glulam is a woody material, it is necessary to be more careful in a gluing process. It takes 6-7 hours at $40-60^{\circ}C$ to harden PRF resin used in making structural glulam, and about 24 hours at room temperature. In the present process which can not use a press continuously, reducing the hardening time is necessary to increase production. The experiment was done to compare the adhesive properties of PRF resin and MUF resin through bending test, block shear strength test and water soaking test. In comparing the bending strength of prediction MOE is 1.2 times higher that actual MOE. PRF and MUF do not show significant difference in MOE and MOR, and in block shear strength test, such as shear strength and wood failure rate. However, in water soaking and boiling water soaking tests PRF and MUF show the significant difference in delamination rate.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.5
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• pp.691-700
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• 2006

This study conducted to optimize the design and operation of orifice typed distribution channels which were generally constructed to link the rapid mixing process and flocculation/sedimentation basin. To accomplish the goal of this study, programming step method using FORTRAN 90, was applied it to simulate the performance of existing distribution channel in the selected S DWTP (Drinking Water Treatment Plant). The proposed step method program was validated in terms of the feasibility with comparison between the measurement and prediction value in each orifice. From the evaluation results of the current conditions with the design and operation, it was revealed that the existing gradient of the tapered channel is not appropriate. Also, we suggested that in the case of the inlet width being 3.5m, reducing the downstream width by about 0.5m would make more equitable distribution flow in the channel. Consequently, dealing with various conditions of the design and operation with distribution channel, we could conclude that for the parallel typed channel, as the width is wider and the diameter of orifice is smaller, the more equitable distribution occur. In addition, the inlet flowrate and the number of orifice can affect the flow velocity in the channel.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.335-342
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• 2011

Secondary effluent contains particle compounds which are comprised of microorganisms that occurs membrane fouling when the water is reused. This study evaluates the characteristics of membrane fouling of secondary effluent reuse. Effects of chemical backwashing are analyzed to reduce membrane fouling by regular chemical backwashing. As the result, major membrane foulants are verified EPS materials which include protein and polysaccharide that cause biofilm cake layer on the membrane. Also, sodium hypochlorite is applied to chemical backwashing. The backwashing improves recover rate when injected chemical concentration is increased and chemical backwashing cycle is amplified. Chemical backwashing cycle affects more than injected chemical concentration yet idle time does not noticeably influence on reducing membrane fouling.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.111-120
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• 2000

In case of constructing concrete structure under water, generally concrete mixed with antiwashout admixture, high range water reducer, or AE-water reducing agent etc has been manufactured to ensure the quality of antiwashout underwater concrete because of being difficulty in ascertaining construction situation by the naked eye. The properties of high quality antiwashout underwater concrete that were aimed at affluent fluidity, workability and the compressive strength of 450 kgf/$\textrm{cm}^2$ at 28 ages using two types of blended cements are following as;(1) Setting time of antiwashout underwater concretes using blended cements was more greatly delayed than that of control concrete, however, was satisfied with criteria value of "Quality standard specification of antiwashout admixture for concrete".(2) As a test results of slump flow, efflux time and box elevation of head, it was found that workability of high quality antiwashout underwater concrete was improved. (3) Heat evolution amount of OPC was 1.5 times as high as that of two types of bended cements in 72 hours. (4) Suspended solids of antiwashout underwater concrete using blended cements was more than that of control concrete, also compressive strength of high quality antiwashout underwater concrete was very low in early age, but was better than that of control concrete as to increasing ages.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.276-281
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• 2000

A simulation program using the mass transfer correlation was constructed to analyze 1-D simplified condensing flow across the tube bank. Higher efficiency was anticipated by reducing the flue gas temperature down below the dew point where the water vapor in the flue gas is condensed at the surface of the heat exchanger; that is, the heat transfer by the latent heat is added to that by the sensible heat. Thus, there can be an optimum operating condition to maximize the heat recovery from the flue gas. The temperature rises of the flue gas and the cooling water between the inlet and the outlet of the tube bank were compared with the experimental data reported previously. The predicted results agree well with the experimental data. Using this simulation program, the parametric studies have been conducted fur various operating conditions, such as the velocities and temperatures of the vapor/gas mixture and the cooling water, the number of the rows, and the conductivity of the wall material.

• Water for future
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• v.27 no.2
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• pp.121-128
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• 1994

Reduced trend of surface velocity, length of the separated drop area and width of potential core have been verified through experimental study of flow characteristics at the step down. To inverstigate sediment behaviors, experimental study which involved accumulated sediment transport reducing water velocity in the separated drop area was performed. From the experimental results, surface velocity, length of the separated drop area and width of potential core were formulated, and calculated output was corroborated by experimental outcome. Furthermore an examination of the parameter which is defined by $q_{sf}$/$q_{uo}$ was performed by detecting sediment in the separated drop area. Therefore these experiments can express the phenomena of flow characteristics and sediment behaviors at the step down.

• Resources Recycling
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• v.15 no.5 s.73
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• pp.52-56
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• 2006

Waste aluminum dross was leached with hydrochloric acid to prepare PAC, poly aluminium chloride, used as water treatment chemicals. Metallic aluminum remained in the waste aluminum dross was dissolved into the hydrochloric acid solution. The solution could be used as PAC after adjusting the required alumina concentration and the basicity. Comparing to the conventional method far preparation of PAC using aluminum hydroxide, material cost could be saved in this method. Also, there is an additional merit in view of recycling of the waste aluminum dross by reducing the amount of waste dross to be landfilled.

• Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.71-78
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• 2013

Subcritical water hydrolysis was carried out in a batch reactor to produce valuable materials, such as low-molecular weight (MW) peptides and essential amino acids with antioxidant properties, from heat-dried squid viscera. Hydrolysis of squid viscera was performed at 160 to $280^{\circ}C$ for 3 min. The yield was increased by increasing the temperature and pressure, while the protein content of squid viscera hydrolysate decreased with increasing temperature. Low-MW peptides were detected in all hydrolysates by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The highest yields of free and structural amino acids in heat-dried squid viscera hydrolysate were at $160^{\circ}C$ and were $411.95{\pm}1.15$ and $346.62{\pm}1.25$ mg/100 g, respectively. All essential amino acids were detected in viscera hydrolysates; leucine was the most abundant. Antioxidant activities of hydrolysates were highest at $220^{\circ}C$. Greater than $98{\pm}0.26%$ of the ABTS antioxidant activity was retained in hydrolysates after long-term heat treatment.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.3
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• pp.221-230
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• 2020

In actual seawater desalination plant, the pressure loss due to frictional force of pipe is about 3~5 bar. Also, the pressure loss at pipe connection about 1~3 bar. Therefore, the total pressure loss in the pipe is expected to be about 4~8 bar, which translates into 0.111 to 0.222 kWh/㎥ of energy when converted into the Specific Energy Consumption(SEC). Reducing energy consumption is the most important factor in ensuring the economics of seawater desalination processes, but pressure loss in piping is often not considered in plant design. It is difficult to prevent pressure loss due to friction inside the pipe, but pressure loss at the pipe connection can be reduced by proper pipe design. In this study, seawater desalination plant piping analysis was performed using a commercial network program. The pressure loss and SEC for each case were calculated and compared by seawater desalination plant size.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.51-59
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• 2005

The long-lived fission product $^{99}Tc$ is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species $TcO_4^-$ whereas under the reducing conditions it is generally predicted that technetium will be present as $TcO_2{\cdot}nH_2O$. Technetium oxide was prepared by reduction of a technetate solution with $Sn^{2+}$. The concentration of total technetium and Tc(IV) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the $^{99}Tc$ with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(IV) in simulated groundwater and redistilled water is about $(1.49{\~}1.86){\times}10^{-9} mol/(L{\cdot}d$) under aerobic conditions, but Tc(IV) in simulated groundwater and redistilled water is not oxidized under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(IV) oxide in simulated groundwater and redistilled water is equal on the whole.