• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.233-239
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• 2013

This study was carried out to develop the realtime evaluation system of $NH_3$ absorption efficiency with gas sensors which were installed on the inlet and outlet of lab-scale scrubber system. The $NH_3$ absorption amount, calculated by sensor outcomes for 3 hr, 6 hr, and 12 hr of absorption process, was compared with the results analysed by Indo-phenol method for the absorption solution. Even though the difference between two methods was about 20%, the correlation coefficient between the two results was very high, more than 0.99. In addition, we could find very good correlation between pH, absorption amount and reaction time. Also we could find out the breakthrough time in the middle of absorption process. With more diverse experiment in the future, we can make gas sensor system for the realtime evaluation of the odor and/or air pollution treatment efficiency.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.1 no.1
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• pp.81-92
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• 2003

In order to predict the dynamic behaviors of uranium and cobalt in a fixed bed at various influent pH values of liquid waste, the adsorption system is regarded as a multi-component adsorption between each ionic species in the solution. Langmuir isotherm parameters of each species were extracted by incorporating equilibrium data with the solution chemistry of the uranium and cobalt using IAST. Prediction results were in good agreement with the experimental data, except for a high concentration and pH. Although there was some limitations in predicting the cobalt adsorption, this method may be useful in analyzing a complex adsorption system where various kinds of ionic species exist in a solution.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.452-456
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• 2008

Mesoporous silicate materials have been used as adsorbents due to the advantage of high specific surface area and regular mesopores. In this study, conventional mesoporous silicates (MCM-41, and SBA-15) were utilized as adsorbents for gaseous benzene, one of volatile organic compounds. In the results of the breakthrough curves of gaseous benzene, SBA-15 showed a higher benzene adsorption capacity in adsorption condition of this study. Especially, compared to benzene adsorption of zeolite X, that of SBA-15 was higher by a factor of 2.7. With increasing adsorption temperature, adsorption capacity for benzene of SBA-15 was decreased rapidly. This indicates that benzene adsorbed weakly on SBA-15.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.539-546
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• 2017

In this study, an outstanding anion exchange chemical filter was prepared for acidic gas removal. Commercial anion exchange resin was attached to polyurethane (PU) foam by using different types of pressure sensitive adhesive (PSA). The water and chemical resistance and also adhesive elongation were investigated. Also, the behavior of HCl and HF adsorption was evaluated as functions of the initial concentration and flow rate. ATE-701, AT-4000C and HCA-1000 showed 900, 1,500% and 2,400% of the elongation, respectively. It was confirmed that the desorption ratio of HCA-1000 was less than 6% and had excellent durability in water and chemical resistance tests. The adsorption occurred faster as the concentration and flow rate of HCl and HF increased. But 100% adsorption equilibrium occurred after 110 minutes, regardless of the concentration and flow rate. In addition, SEM morphology showed that the adhesive was uniformly dispersed, while the porous structure of the ion exchange resin was maintained, and the chemical filter exhibited excellent durability for the adsorption/desorption process.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.91-99
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• 2007

It is well-known that the presence of NOM (natural organic matter) in water has a negative effect on removing taste and odor compounds by activated carbon adsorption. Therefore, various means such as enhanced coagulation are applied to reduce the NOM. The presence of taste & odor compounds in drinking water even parts per trillion, is enough to generate customer dissatisfaction. Therefore, the aim of this study was to evaluate carbon usage rate (CUR) for conventional coagulation (CC) and enhanced coagulation (EC) in order to improve the efficiency of adsorption of taste and odor compounds. Also, Effect of CC and EC on molecular weight fraction and the early stage breakthrough of 2-MIB and Geosmin are evaluated. When the enhanced coagulation was adapted for pretreatment for activated carbon adsorption the operation period could be prolonged by 3.5~4 times. CUR for CC was about 2 times greater than CUR for EC and this means that EC has more adsorption capacity than CC. To analyze effect of EC and CC on breakthrough of 2-MIB quantitatively, adsorbed NOM mass was calculated based on unit mass of activated carbon. In the early stage breakthrough of 2-MIB, total adsorbed NOM was 23.72mg/g for CC and 34.56mg/g for EC. Therefore, it is shown that the early breakthrough term of 2-MIB and Geosmin was improved due to increased adsorbability. The low-molecular-weight NOM (500~2000Da) compounds were the most competitive, participating in direct competition with 2-MIB for adsorption site.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.723-731
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• 2000

In recent years, the amount and number of synthetic organic compounds(SOCs) discharged from various industries has been increasing. Granular activated carbon(GAC) adsorption is one of the best available technology to remove SOCs from water supplies and wastewater. In this paper competitive adsorption for binary mixture of 4-nitrophenol and phenol on reverse stratified tapered adsorber(RSTA) using GAC was studied. Two isotherm experiments were conducted, one for phenol and the other for 4-nitrophenol. The phenol data of binary mixture isotherm were not fitted to Freundlich isotherm. The competitive adsorption increased significantly with decreasing carbon dose and increasing adsorbate concentration. The RSTA was found to provide an increase in breakthrough time when decreasing flow rate, increasing angle and injection layers. The performance enhancement provided by RSTA can be exploited in separation and in the purification of fluids.

• Journal of the Korean Ceramic Society
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• v.28 no.1
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• pp.19-19
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• 1991

Fracture of Al2O3 tubes for different loading path under combined tension/torsion was investigated. Macroscopic directions of crack propagation agreed well with the maximum principal stress criterion, independent of the loading path. However, fracture strength from the proportional loading test(τ/σ= constant) showed either strengthening or weakening compared to that from uniaxial tension, depending on the ratio τ/σ. The Weibull theory was capable to predict the strengthening of fracture strength in pure torsion, but not the weakening in the proportional loading condition. The strengthening or weakening of fracture strength in the proportional loading condition was explained by the effect of shear stresses in the plane of randomly oriented microdefects. Finally, a new empirical fracture criterion was proposed. This criterion is based on a mixed mode fracture criterion and experimental data for fracture of Al2O3 tubes under combined tension/torsion. The proposed fracture criterion agreed well with experimental data for both macroscopic directions of crack propagation and fracture strengths.

• KSBB Journal
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• v.19 no.2
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• pp.104-109
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• 2004

Activated carbon has been used in water treatment, because they strongly adsorb organic material including contaminant. Water purifier usually use activated carbon, and bacterial regrowth on that could induce many problems. Model columns, packed with coal- and plant-based granular activated carbon (GAC), were operated with rechlorinated tap water to compare the degree of bacterial regrowth on different GACs. GAC columns decreased the concentration of total organic carbon and chlorine, while they are not good for the decrease of ions. Breakthrough of bacteria were occurred after eight days of operation, and reached 1.1 ${\times}$ 10$^3$ CFU/mL on coal based GAC and 6.2 ${\times}$ 10$^2$ CFU/mL on coconut based one. Bacterial activities on GAC were between 15.35 ∼ 29.06 $\mu\textrm{g}$ INT-formazan/g-GAC/h. Bacterial concentration and activities were higher in coal based GAC than coconut based one. Bacterial regrowth on GAC was clarified and regrowth effect of coal-based GAC was higher than that of coconut-based one.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.277-285
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• 2007

The adsorption characteristics of multi-component solvent vapors including poorly-adsorbable chemicals such as toluene-xylene-MEK and toluene-MEK-IPA on the activated carbonaceous adsorbents were investigated in a stainless steel fixed bed of 10.2 cm ID and 50 cm in height in order to identify those carbons for eliminating and recovering solvent vapors from industrial emission sources. The used activated carbonaceous adsorbents were pelletized commercial activated carbons and activated carbon fiber. Breakthrough curves and adsorption capacity at atmospheric pressures were obtained. It has been found that non-polar and larger molecules have been adsorbed better than polar and smaller molecules. In special, alcohols and ketones were poorly adsorbed caused by competitive adsorbability in multi-component mixture system. However, it could be overcome by profitable employment of organization of cooperative system which was composed of different porosity activated carbonaceous adsorbents appropriately.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2752-2761
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• 1993

The purpose of this study is to confirm the decreasing problems of residual bending strength, and the fracture machanism experimentally when CFRP composite laminates are subjected to Foreign Object Damage. Composite laminates used for this experiment are CFRP orthotropy laminated plates, which have two-interfaces [O/sub 6//sup o//90/sub 6//sup o/]sub sym/ and four-interfaces [O/sub 3//sup o//90/sub 6//sup o//O/sub 3//sup o]/sub sym/. When the specimen is subjected to transverse impact by a steel ball, the delamination area generated by impact damage is observed by using SAM(Scanning Acoustic Microscope). also, Thefracture surfaces obtained by three-point bending test were observed by using SEM (Scanning Electron Microscope). Then, fracture mechanism was investigated based on the observed delamination area and fracture surface. The results were summarized as follows; (1) It is found that for the specimen with more interface, the critical delamination energy is increased while delamination-development energy is decreased. (2) Residual bending strength of specimen A is greater than that of Specimen B within the impact range of impact energy 1. 65J (impacted-side compression) and 1. 45J (impacted-side tension). On the other hand, when the impact energy is beyond the above ranges, residual bending strength of specimen A is smaller than that of specimen B. (3) In specimen A and B, residual strength of CFRP plates subjected to impact damage is lower in the impacted-side compression than in the impacted-side tension. (4) In the case of impacted-side compression, fracture is propagated from the transverse crack generat-ed near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-B delamination in the case of impacted-side tension.