• Journal of Korean Society for Atmospheric Environment
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• v.22 no.6
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• pp.779-790
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• 2006

This study examines relative contributions of volatile organic compounds (VOCs) to the formation of hydroxyl (OH) and peroxy radicals such as $HO_2$ and $RO_2$ during the intensive sampling period (Jun. $1{\sim}30$, 2004) in the air of Seoul metropolitan area. As to the contribution of VOCs to $HO_x$ levels, the impact of individual VOC concentration change on $HO_2$ concentration change was more than an order of magnitude higher than that on OH concentration change during the study period. The contribution of change in isoprene concentration to $HO_2$ concentration change was 38 times higher than OH and that in the concentration of alkene compounds to $HO_2$ concentration change was 31 times higher than OH. Moreover, the concentration changes of isoprene and aromatic compounds (AROM) played significant roles in $HO_x$ concentration changes. On the other hands, aldehydes (ALD2) and alkanes (ALKA) showed anti-correlation (negative) in $HO_x$ concentration changes with low contribution ($-4{\times}10^{-3}$ pptv/ppbv (OH) and $-58{\times}10^{-3}$ ($HO_2$) for ALD2; $-1{\times}10^{-3}$ (OH) and $-15{\times}10^{-3}$ ($HO_2$) for ALKA). Unlike other VOCs, $C_2H_6$ and $C_3H_8$ showed positive or negative contribution to peroxy radicals, depending on ambient air conditions. The contribution of VOC concentration changes to changes in $CH_3O_2$ and $RO_2$ concentration showed similar pattern to $HO_x$ contribution.

• Advances in Traditional Medicine
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• v.5 no.3
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• pp.246-250
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• 2005

A number of species of the genus Centaurea (Family: Asteraceae), distributed in various parts of Asia, Europe and North America, have been used in traditional plant-based medicine and reported to possess various medicinal properties. As part of our continuing evaluation of plants from the genus Centaurea for their phytochemistry and biological activities, the dichloromethane (DCM) and methanol (MeOH) extracts of the seeds of Turkish Centaurea species, C. bornmuelleri, C. huber-morathii and C. schiskinii, were screened for antioxidant and antibacterial activities. Among the three species, C. huber-morathii displayed the most prominent antibacterial activity. Both the MeOH and DCM extracts of this plant showed activity against Citrobacter freundii, Enterococcus faecalis and Salmonella goldcoast with the MIC values within the range of $1\;{\times}\;10^{-2}\;to\;1\;{\times}\;10^{-3}\;mg/ml$. The MeOH extract of C schiskinii showed activity $(MIC\;=\;1\;{\times}\;10^{-1}\;mg/ml)$ against Citrobacter freundii and Staphylococcus aureus. While the DCM extract of C. bornmuelleri was only active against Staphylococcus aureus $(MIC\;=1\;{\times}\;10^{-2}\;mg/ml)$, the MeOH extract did not show any inhibitory activity at test concentrations. The DCM and MeOH extracts of all three species demonstrated good degree of antioxidant property in the DPPH assay with the $RC_{50}$ values ranging from $72\;{\times}\;10^{-2}\;to\;31{\times}\;10^{-3}\;mg/ml$. Among these extracts, the MeOH extract of C. hubermorathii was the most active antioxidant extract $(MlC\;=\;31\;{\times}\;10^{-3}\;mg/ml)$.

• KSBB Journal
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• v.6 no.3
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• pp.241-247
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• 1991

The Poly (4-vinyipyridine-co-styrene) membrane containing Pyridine as fixed carrier was synthesized and characterized. And the active transport mechanism of Cl- and $CCl_3COO^-$ with changing concentration of $H^+$ and $OH^-$ was investigated. $CCl_3COO^-$ was transported not only by a symport mechanism with $H^+$ transfer but also by an antiport mechanism with $OH^-$transfer, while $Cl^-$ was transported only by a symport mechanism with $H^+$ transfer. Observing the initial flux of anions, salt formation constant between ions and membrane (K), and diffusion coefficient in membrane (D) were calculated as follows: for $Cl^-, \;K=4.60{\times}10^2\;mol^{-1}{\cdot}\textrm{cm}^3, \;D=1.57{\times}10^{-3}{\textrm{cm}^2/h$ and for $CCl_3COO^-, \;K=1.l0{\times}10^4\;mol^{-1}{\cdot}\textrm{cm}^3, \;D=1.14{\times}10^{-4}{\textrm{cm}^2}/h$.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.432-439
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• 2018

Metal catalysts such as Fe, Co, Mn, and Pd supported on the activated carbon (AC) were prepared to improve functional groups for the chemical adsorption and catalytic ozonation. Following ascending orders of the phenol decomposition rate, dissolved ozone decomposition ratio and TOC (total organic carbon) removal from experimental results of advanced oxidation process (AOP) were observed: Fe-AC < AC < Co-AC < Mn-AC < Pd-AC. BET analysis results showed that the physical properties of the metal impregnated activated carbon had no effect on the catalytic ozonation, and the catalytic effect was dependent on the kind of impregnated metal. The ratio of the formed concentration of OH radical to that of ozone (RCT) was measured by using the decomposition outcome of p-chlorobenzoic acid, a probe compound that reacts rapidly with OH radical but slowly with ozone. The measured values of RCT were $5.48{\times}10^{-9}$ and $1.47{\times}10^{-8}$ for the ozone alone and activated carbon processes, respectively, and $2.13{\times}10^{-9}$, $1.51{\times}10^{-8}$, $4.77{\times}10^{-8}$, and $5.58{\times}10^{-8}$ for Fe-AC, Co-AC, Mn-AC, and Pd-AC processes, respectively.

• Resources Recycling
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• v.4 no.1
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• pp.31-37
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• 1995

This study was to investigate the effects oi agitation speed, pulp concentration, ion concentration ill the slurry solution, printed area of the waste newspaper, immerwng time and the temperature on the defiberation process for the waste newspaper. The defikration efficiency at 50% is twice that of 16%. The efficiency is improved as two times according to elevate the agtation speed as two times in the range of 200-2WO r.p.m.. Defiberation with NaOH 1X10-'M solution has higher efficiency than that of NaOH 1 x 1 0 - M solution as 3 times at the conditions of 16%, 1200 r.p.m, and 1% pulp concentration The temperature of immersing salut~on aifects on the efficiency more than immersing time does. Increasing the printed area of newspaper decreases the velocity of defiberation. The alkaline solution is effective to defiberate and the defiberation efficiency at the same dosage of alkalinity is in the order a1 NaOH) KOH) Na,SiO, ) Na,CO, ) Ca(OH)2.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.184.2-184.2
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• 2013

대기압 플라즈마와 생체용액과의 상호작용은 Bio-medical 분야에서 주목 받고 있다. 대기압 플라즈마는 전자온도가 고온 플라즈마 보다 상대적으로 낮기 때문에 생체에 적용하기가 적합하다. 따라서 플라즈마가 세포에 미치는 영향을 관측하기 위해서 대기압 플라즈마를 이용하여 생체용액과의 반응을 살펴보고자 한다. Ar gas를 이용하여 플라즈마를 발생시켜 생체용액 표면을 처리하고 OES (Optical Emission Spectroscopy)을 이용해 방출 선을 조사했다. Ar 기체를 이용한 대기압 플라즈마를 사용하여 다른종류의 용액내의 OH Radical Density를 측정하였다. 용액으로는 DI (deionized) water 와 PBS (1x phosphate buffered saline)를 사용하였다. Ar gas를 200 sccm ($cm^3/min$) 으로 흐르게 하였을 때, DI water의 OH Radical Density 는 $4.33{\times}10^{16}cm^{-3}$ 으로 측정되었으며, 자외선 흡수분광법으로 측정한 완충용액인 PBS의 OH Radical Density 측정값은 $1.87{\times}10^{16}cm^{-3}$ 이다. 이런 특성을 기반으로, PBS 용액내의 H460 (Lung Cancer Cell) 와 L132 (Lung Normal Cell)을 깊이와 시간에 따라 대기압 플라즈마로 처리하여 cell의 변화를 보았다. 실험 각각의 조건은 깊이를 2 mm, 4 mm, 6 mm이며 시간은 10 sec, 30 sec, 60 sec 로 설정하였다. 표면으로부터의 깊이가 2 mm, 4 mm, 6 mm 일때 의 OH Radical Density는 각각 $1.87{\times}10^{16}cm^{-3}$, $0.5{\times}10^{16}cm^{-3}$, 0으로써 용액이 깊어질수록 OH Radical Density가 감소함을 볼 수 있다. OH radical density가 높은 2 mm 에서, 처리한 시간이 길어질수록 Cell 은 영향을 많이 받음을 관찰 할 수 있었다. H460 이 L132 보다 플라즈마에 영향을 많이 받음을 확인하였다. 특성변화를 알아보기 위하여 raman spectroscopy, flow cytometry, electron spin resonance로 측정한다.

• Journal of Korean Society on Water Environment
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• v.38 no.2
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• pp.82-94
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• 2022

In this study, chemically modified biochar (NSBP500, KSBP500, OSBP500) derived from starfish was utilized to improve the adsorption ability of the SBP500 (Starfish Biochar Pyrolyzed at 500℃) in a solution contaminated with heavy metals. According to the biochar modification performance evaluation batch tests, the removal rate and adsorption amount of NSBP500 increased 1.4 times for Cu, 1.5 times for Cd, and 1.2 times for Zn as compared to the control sample SBP500. In addition, the removal rate and adsorption amount of KSBP500 increased 2 times for Cu, 1.8 times for Cd, and 1.2 times for Zn. The removal rate and adsorption amount of OSBP500 increased 5.8 times for Cu. The FT-IR analysis confirmed the changes in the generation and movement of new functional groups after adsorption. SEM analysis confirmed Cu in KSBP500 was in the form of Cu(OH)₂ and resembled the structure of nanowires. The Cd in KSBP500 was densely covered in cubic form of Cd(OH)₂. Lead(Pb) was in the form of Pb₃(OH)₂(CO₃)₂ in a hexagonal atomic layer structure in NSBP500. In addition, it was observed that Zn was randomly covered with Zn₅(CO₃)₂(OH)₆ pieces which resembled plates in KSBP500. Therefore, this study confirmed that biochar removal efficiency was improved through a chemical modification treatment. Accordingly, adsorption and precipitation were found to be the complex mechanisms behind the improved removal efficiency in the biochar. This was accomplished by electrostatic interactions between the biochar and heavy metals and ion exchange with Ca²⁺.

• Journal of the Korean Statistical Society
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• v.29 no.2
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• pp.219-229
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• 2000

Oh et al.(1999) 3$\times$2 crossover design for assessing bioequivalence when two new generic drug formulations and innovator are simultaneously considered. This design is not only more efficient than 3$\times$3 one, proposed by Lee et al.(1998), in practical sense, but also more ethical in medical sense. However, the general statistical methods are not directly applicable to both designs when subjects are dropped out in the experiment, even though it is always possible in bioavailability and bioequivalence studies because of some administrative and economic reasons. In this research we propose an inference to drug effects when subjects are dropped out in the planed-for 3$\times$3 and 3$\times$2 crossover experiments. An example is given for illustration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.335-335
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• 2008

Phosphate glass samples with various $Cr_2O_3$ and $Er_2O_3$ contents based upon $55P_2O_5\cdot24BaO\cdot10K_2O\cdot4Al_2O_3\cdot6Yb_2O_3$ were prepared. The prepared glass compositions are dehydrated using gas bubble flow method in open system and investigated the effects of the eliminating of OH groups from the glass melts with bubbling time. It was found that the probability of $Er^{+3}$ fluorescence quenching by OH groups oscillations linear depends upon the OH groups absorption coefficients in the maximum of the stretch vibrations band at $3500cm^{-1}$ while $Er^{+3}$ concentration range is between $1.6\times10^{19}$ and $21.2\times10^{19}$ ion/$cm^3$.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.879-886
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• 2000

$H_2S$ adsorption characteristics of activated carbon adsorbent impregnated with NaOH were investigated. The concentrations of NaOH reagent were 1~8N and the particle size of activated carbon was $8{\times}30$ mesh. The experimental results showed that the BET surface area decreases from $1050m^2/g$ to $783m^2/g$ and acidity of activated carbon decreases from 0.541 meq/g-AC to 0 meq/g-AC, while pH increases from 9.56 to 10.86 when the impregnation ratio increases from 0.87% to 5.8%. It was also found that the $H_2S$ adsorption equilibrium capacity of activated carbon impregnated with NaOH increases with increasing temperature and $H_2S$ concentration and varies in the range of 17.87~30.34 mg/g-AC at adsorption temperature of $45^{\circ}C$, which is 2~3 times larger than that of pure activated carbon.