• Environmental Engineering Research
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• v.17 no.4
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• pp.185-190
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• 2012

Rejection characteristics of perchlorate ($ClO_4^-$) were examined for commercially available reverse osmosis (RO) and nanofiltration (NF) membranes. A bench-scale dead-end stirred-cell filtration system was employed to determine the toxic ion rejection and the membrane flux. Model water solutions were used to prepare $ClO_4^-$ solutions (approximately, $1,000{\mu}g/L$) in the presence of background salts (NaCl, $Na_2SO_4$, and $CaCl_2$) at various pH values (3.5, 7, and 9.5) and solution ionic strengths (0.001, 0.01, and 0.01 M NaCl) in the presence of natural organic matter (NOM). Rejection by the membranes increased with increasing solution pH owing to increasingly negative membrane charge. In addition, the rejection of the target ion by the membranes increased with increasing solution ionic strength. The rejection of $ClO_4^-$ was consistently higher for the RO membrane than for the NF membrane and $ClO_4^-$ rejection followed the order $CaCl_2$ < NaCl < $Na_2SO_4$ at conditions of constant pH and ionic strength for both the RO and NF membranes. The possible influence of NOM on $ClO_4^-$ rejection by the membranes was also explored.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.22-27
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• 2015

Hydrogen features highest energy density per mass and is expected to be desirable as a fuel of HALE(High altitude long endurance) UAV(Unmanned aerial vehicle). A reciprocating internal combustion engine is known to be a reliable and economic power source for this kind of UAV. Therefore, the combination of hydrogen and engine is worth of doing research. Test bench with 2.4L Spark-Ignited engine was prepared for the experiment in which start and combustion characteristics at idle condition were examined in this study. Stable hydrogen supply system and a universal ECU(Engine control unit) were also utilized for the test engine. Equivalence ratio and spark timings at idle operation were investigated and compared to the data of gasoline engine. The results will be a starting point for full-scale research of hydrogen engine for HALE UAV.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.123-130
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• 2002

Bench scale experiments were carried out with two biological nutrient removal(BNR) units, A/O and $A^2O$ processes, to investigate the behavior of phosphorus in the system and to compare the characteristics of phosphorus removal in two BNR processes. To achieve this goal, COD/T-P and COD/TKN ratios of the influent was varied in the range of 23~64 and 5~24, respectively. In A/O process, influent COD/T-P ratio should be kept higher than 44mg/L to meet the final effluent T-P concentration lower than 1mg/L and in $A^2/O$ process, influent COD/T-P and COD/TKN ratios higher than 56 and 10, respectively, were required for good phosphorus release and uptake with no influence of nitrate nitrogen in return sludge. At this conditions, the rate of phosphorus release in the anaerobic basin should be kept higher than 0.1 kg S-P/kg MLVSS d In A/O process, the phosphorus content of anaerobic and aerobic sludges was increased as SRT of total system was becoming longer resulting in decreasing the difference of phosphorus content between two sludges while phosphorus release in anaerobic basin and phosphorus uptake in aerobic basin was not incident. In $A^2/O$ process, the phosphorus content of anaerobic and aerobic sludges were not increased with higher SRT of total system due to the relatively high nitrate concentration in return sludge. However, the difference of phosphorus content between anaerobic and aerobic sludges was incident when phosphorus release and uptake was observed.

• Fire Science and Engineering
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• v.24 no.1
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• pp.116-121
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• 2010

The present study has been performed to investigate the ignition characteristics of a n-dodecane fuel droplet on the hot surface. Simplified bench scale test setup was built to examine the effect of air flow on the ignition temperature of fuel droplet. IR pyrometric sensor was used to measure the surface temperature, the measured temperature using IR pyrometer was directly compared with k-type thermocouple. The ignition of n-dodecane fuel droplet was divided into two stage - cool flame and hot flame - with the air flow rate except the case of air flow rate 3.0 lpm. The ignition temperature and probability was greatly affected by the air flow rate and the MHSIT of the present study was about $300^{\circ}C$ for air flow rate of 0.5 lpm.

• Membrane and Water Treatment
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• v.9 no.2
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• pp.69-77
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• 2018

The use of membrane as an innovative technology for water treatment process has now widely been accepted and adopted to replace the conventional water treatment process in increasing fresh water production for various domestic and industrial purposes. In this study, ultrafiltration (UF) membranes with different formulation were fabricated via phase inversion method. The membranes were fabricated by varying the polymer concentration (16 wt%, 18 wt%, 20 wt%, and 21 wt%). A series of tests, such as field emission scanning electron microscope (FESEM), pore size and porosity, contact angle, and zeta potential were performed to characterize the membranes. The membrane performance in terms of permeation flux and rejection were evaluated using a laboratory bench-scale test unit with mine water, lake water and tube well as model feed solution. Long hour filtration study of the membranes provides the information on its fouling property. Few pore blocking mechanism models were proposed to examine the behaviour of flux reduction and to estimate the fouling parameters based on different degree of fouling. 21 wt% PVDF membrane with smaller membrane pore size showed an excellent performance for surface water treatment in which the treated water complied with NWQS class II standard.

• International Journal of Stem Cells
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• v.10 no.1
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• pp.1-11
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• 2017

Human cardiomyocytes (CMs) cease to proliferate and remain terminally differentiated thereafter, when humans reach the mid-20s. Thus, any damages sustained by myocardium tissue are irreversible, and they require medical interventions to regain functionality. To date, new surgical procedures and drugs have been developed, albeit with limited success, to treat various heart diseases including myocardial infarction. Hence, there is a pressing need to develop more effective treatment methods to address the increasing mortality rate of the heart diseases. Functional CMs are not only an important in vitro cellular tool to model various types of heart diseases for drug development, but they are also a promising therapeutic agent for cell therapy. However, the limited proliferative capacity entails difficulties in acquiring functional CMs in the scale that is required for pathological studies and cell therapy development. Stem cells, human pluripotent stem cells (hPSCs) in particular, have been considered as an unlimited cellular source for providing functional CMs for various applications. Notable progress has already been made: the first clinical trials of hPSCs derived CMs (hPSC-CMs) for treating myocardial infarction was approved in 2015, and their potential use in disease modeling and drug discovery is being fully explored. This concise review gives an account of current development of differentiation, purification and maturation techniques for hPSC-CMs, and their application in cell therapy development and pharmaceutical industries will be discussed with the latest experimental evidence.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.93-99
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• 2018

The purpose of this study was to prove the effect of passive stretching after delayed muscular pain induction in university students and to propose a rehabilitation exercise program for effective pain relief and prevention in case of injury. Subjects were divided into passive stretching group and control group. Passive stretching group was performed passive stretching after delayed muscular pain induction and control group did not perform any treatment after delayed muscular pain induction. The delayed muscular pain induction method was induced by bench step motion. The height of the step box was 50cm. The data were analyzed by two-way RGRM ANOVA for comparison of passive stretching group and control group. In conclusion, passive stretching after delayed myalgia has a positive effect on blood fatigue (CRP, LDH) and subjective pain scale(VAS).

• Journal of Applied Biological Chemistry
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• v.61 no.4
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• pp.335-340
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• 2018

Hemoglobin (Hb) is a member of heme-protein that can perform catalytic non-specific chain reaction in the presence of hydrogen peroxide ($H_2O_2$). Catalytic ability of Hb to degrade pyrene was demonstrated using soil contaminated with $^{14}C$ pyrene and 10 mg pyrene /kg soil. The composition of soil was similar to previously used soil except that it had lower organic carbon content. Bench scale laboratory tests were conducted in the presence of buffer only, $H_2O_2$ only, or Hb with $H_2O_2$ for 24 h. After 24 h reaction, 0.1 and 1.3% of $^{14}C$ pyrene in contaminated soil were mineralized with $H_2O_2$ only or Hb plus $H_2O_2$. No mineralization to $^{14}CO_2$ was detected with buffer only. Approximately 12.2% of pyrene was degraded in the presence of $H_2O_2$ only while 44.0% of pyrene was degraded in the presence of Hb plus $H_2O_2$ during 24 h of catalytic reaction. When degradation intermediate products were examined, two chemicals were observed in the presence of $H_2O_2$ only while 25 chemicals were found in the presence of Hb plus $H_2O_2$. While most degradation products were simple hydrocarbons, four of the 27 chemicals had aromatic rings. However, none of these four chemicals was structurally related to pyrene. These results suggest that Hb catalytic system could be used to treat pyrene-contaminated soil as an efficient and speedy remediation technology. In addition, intermediate products generated by this system are not greatly affected by composition change in soil organic matter content.

• Clean Technology
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• v.15 no.3
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• pp.186-193
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• 2009

The characteristics of product materials obtained from thermal degradation of low-qualify pyrolytic oil were investigated in this study. The reactants were produced by pyrolysis of mixed plastic waste with film type in a commercial rotary kiln reaction system. The properties of reactants were measured by elemental analysis, calorimetry analysis and SIMDIST analyst. The result of degradation experiments with different reaction temperature programs was discussed through product yields, cumulative yields and production rates of oil products. The multi-step reaction temperature program resulted in higher yields of product oils and lower yields of residues than one-step reaction temperature program. The product characteristics such as production yield and the rate of oil products etc. were influenced by reaction temperature program in the continuous thermal degradation.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.419-425
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• 2017

In this study, the performance characteristics of the K-based sorbents (KEP-CO2P2, KEPCO RI, Korea) has been studied in relation with the heat exchanger structure and shape in a mixing zone of the carbonator in the bench-scale dry $CO_2$ capture process. Two types of heat exchangers (different structure and shape) were used in the carbonator as CASE 1 and CASE 2, in which the experiment has been continuously performed under the same operating conditions. During the continuous operation, working temperature of carbonator was 75 to $80^{\circ}C$, that of regenerator was 190 to $200^{\circ}C$, and $CO_2$ inlet concentration of the feed gas was 12 to 14 vol%. Especially, to compare the dynamic sorption capacity of sorbents, the differential pressure of the mixing zone in the carbonator was maintained around 400 to 500 mm $H_2O$. Also, solid samples from the carbonator and the regenerator were collected and weight variation of those samples was evaluated by TGA. The $CO_2$ removal efficiency and the dynamic sorption capacity were 64.3% and 2.40 wt%, respectively for CASE 1 while they were 81.0% and 4.66 wt%, respectively for CASE 2. Also, the dynamic sorption capacity of the sorbent in CASE 1 and CASE 2 was 2.51 wt% and 4.89 wt%, respectively, based on the weight loss of the TGA measurement results. Therefore, It was concluded that there could be a difference in the performance characteristics of the same sorbents according to the structure and type of heat exchanger inserted in the carbonator under the same operating conditions.