• Environmental Engineering Research
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• v.22 no.3
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• pp.329-338
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• 2017

Nanofiltration (NF) technology is a membrane-based separation process, which has been pervasively used as the high-effective technology for drinking water treatment. In this study, a kind of composite polyamide NF thin film is selected to investigate the removal efficiencies and mechanisms of 14 trace drugs, which are commonly and frequently detected in the drinking water. The results show that the removal efficiencies of most drugs are quite high, indicating the NF is an effective technology to improve the quality of drinking water. The removal efficiencies of carbamazepine, acetaminophen, estradiol, antipyrine and isopropyl-antipyrine in ultrapure water are $78.8{\pm}0.8%$, $16.4{\pm}0.5%$, $65.4{\pm}1.8%$, $71.1{\pm}1.5%$ and $89.8{\pm}0.38%$, respectively. Their rejection rates increase with the increasing of their three-dimensional sizes, which indicates that the steric exclusion plays a significant role in removal of these five drugs. The adsorption of estradiol with the strongest hydrophobicity has been studied, which indicates that adsorption is not negligible in terms of removing this kind of hydrophobic neutral drugs by NF technology. The removal efficiencies of indomethacin, diclofenac, naproxen, ketoprofen, ibuprofen, clofibric acid, sulfamethoxazole, amoxicillin and bezafibrate in ultrapure water are $81{\pm}0.3%$, $86.3{\pm}0.5%$, $85.7{\pm}0.4%$, $93.3{\pm}0.3%$, $86.6{\pm}2.5%$, $90.6{\pm}0.4%$, $59.7{\pm}1.7%$, $80.3{\pm}1.4%$ and $80{\pm}0.5%$, respectively. For these nine drugs, their rejection rates are better than the above five drugs because they are negatively charged in ultrapure water. Meanwhile, the membrane surface presents the negative charge. Therefore, both electrostatic repulsion and steric exclusion are indispensable in removing these negatively charged drugs. This study provides helpful and scientific support of a highly effective water treatment method for removing drugs pollutants from drinking water.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.633-641
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• 2008

Since WSNs encounter attacks, such as jamming or eavesdropping without physical access occurs, security is one of the important requirements for WSNs. The key pre-distribution scheme that was recently researched for advance of security in WSNs distributes the keys and probability with the use of q-composite random key pre-distribution method, but there is a high probability that no key shared between sensor nodes, and it takes a lot of time and energy to find out the shared key. Therefore, it is not suitable for WSNs. In order to enhance stability of a node that plays a role of gateway without depending on probabilistic key, this paper proposesa key pre-distribution scheme combined with random key pre-distribution scheme and double hash chain. Since the proposed scheme can maintain a small storage place and strong security strengths, it is more efficient than the existing schemes with the same security strengths. In addition, since it uses a small size of key generation key set, it can reduce a great deal of storage overhead.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.1
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• pp.1-7
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• 2016

Highly porous polymethyl methacrylate (PMMA) microspheres impregnated by $TiO_2$ powder were prepared by spray drying method. The particle size and the porosity were controlled by optimizing the co-solvent ratio and the polymer concentration. $TiO_2$ powder was impregnated into the microspheres upto 74.6 wt% content based on the weight of the resultant $PMMA/TiO_2$ microspheres. SEM images showed that $TiO_2$ powder was well distributed throughout the inside of the microsphere. EDX mapping showed that the Ti signal was well detected from every part of the microspheres, which was the evidence of the formation of the $PMMA/TiO_2$ composite. Hg porosimetry result showed that the porosity was found to be over 50% regardless of the $TiO_2$ contents. The final product was found to have high oil-absorbing capacity and great hiding power, both of which are key properties in designing the microsphere materials for make-up cosmetics application.

• Food Science and Preservation
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• v.23 no.3
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• pp.319-325
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• 2016

This study was designed to develop a manufacturing process for ginseng concentrate with reduced unpleasant aroma and bitter taste. Two types of ginseng, white and red, were extracted under six different conditions (the 1st to the 6th step) of temperature ($65{\sim}95^{\circ}C$) and ethanol concentration (0~70%). Six extracts of each ginseng were evaluated by a sensory test, and assayed for crude saponin, ginsenosides, and acidic polysaccharides. The content of crude saponin in the extracts decreased with extraction time. There was no significant difference in the crude saponin content between white and red ginseng extracts. The yield of red ginseng extract was higher (45%) than that of white ginseng. No significant difference was observed in the acidic polysaccharide content between red and white ginseng extracts. $Rg_3$, a specific ginsenoside in red ginseng, was detected in the 1st to 6th extracts of red ginseng. Bitterness, astringency, and sourness of ginseng extracts decreased as the extraction steps proceeded. The composite of the 1st, 2nd, and 6th step extracts decreased bitterness and astringency, and the highest overall acceptance. Compared with commercial beverages, the composition of the three extracts is the desirable method to decrease the bitter and astringent tastes, and the overall unpleasant flavor of ginseng.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.67-75
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• 2014

A full-scale static test for a composite structure small aircraft (KC-100) was conducted in the KARI. The test includes 15 full-scale test and 7 local test conditions. Test requirements with test schedule, test article with dummy structures, test load generation, test system, and equipment are introduced for the test. Test load data of the 1st test condition(U1) was analyzed to evaluate an accuracy of load control for the test. The analysis results show that load data obtained during test were within tolerance of Static Null Pacing Error(SNPE) and the error value of load control was 8.6N. The error of load controls for the full-scale static test using dozens of actuators was calculated by a method suggested by authors. Test data for all other test conditions is also shown in this paper. Finally, reactions measured from restraint system of the U1 test condition show that the reaction changes as load increment. The factors which may change the change of reactions for a full-scale static test are introduced in this study.

• Clean Technology
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• v.19 no.3
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• pp.300-305
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• 2013

Zinc oxide (ZnO) and reduced graphite oxide (rGO) composites were synthesized and tested as adsorbents for the hydrogen sulfide ($H_2S$) adsorption at mid-to-high (300 to $500^{\circ}C$) temperatures. In order to investigate the critical roles of oxygen containing functional groups, such as hydroxyl, epoxy and carboxyl groups, attached on rGO surface for the $H_2S$ adsorption, various characterization methods (TGA, XRD, FT-IR, SEM and XPS) were conducted. For the reduction process for graphite oxide (GO) to rGO, a microwave irradiation method was used, and it provided a mild reduction environment which can remain substantial amount of oxygen functional groups on rGO surface. Those functional groups were anchoring and holding nano-sized ZnO onto the 2D rGO surface; and it prevented the aggregation effect on the ZnO particles even at high temperature ranges. Therefore, the $H_2S$ adsorption capacity had been increased about 3.5 times than the pure ZnO.

• Journal of the Korean Ceramic Society
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• v.42 no.8 s.279
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• pp.561-566
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• 2005

For the homogeneous dispersion of $ZrO_2$ particles in $Al_2O_3/ZrO_2$ceramics, Zr-precusors were mixed with oxide $Al_2O_3$powders by chemical routes such as partial precipitation or partial polymerization of Zr-nitrate solutions. In case of the mechanical mixing of ultrafine $Al_2O_3$ and $ZrO_2$ oxide powders, relatively homogeneous dispersion was difficult to achieve so that the particle size and distributions of $ZrO_2$ were relatively inhomogeneous after sintering at high temperature. But when the Zr-Y-hydroxide were co-precipitated to ultrafine $Al_2O_3$ oxide powders followed by calcinations, homogeneous dispersion of nano-sized $ZrO_2$ particles in $Al_2O_3/ZrO_2$ composite ceramics were obtained. But because of the coalescence of dispersed $ZrO_2$ particles, dispersed $ZrO_2$ was grown up to more than 0.2${mu}m$ (200 nm) when sintered at the temperature of higher than $1500^{\circ}C$ But when the sintering temperature was kept to lower than $1400^{\circ}C$ by using nano-sized $\alpha-alumina$, the particle size of dispersed $ZrO_2$ could be sustained below 0.1 ${\mu}m$. But the coalescence of dispersed $ZrO_2$ between $Al_2O_3$ particles could not be avoided so that the mechanical properties were not enhanced contrary to the expectations. So Zr-polyester precursors were precipitated and coated to the surface of ultrafine $\alpha-alumina$ powders by the polymerization of Ethylene Glycol with Citric Acid and Zirconium Nitrate. By this dispersion much more uniform dispersion of $ZrO_2$ was achieved at $1450\~1600^{\circ}C$ of sintering temperature ranges. And due to especially discrete dispersion of $ZrO_2$ between $Al_2O_3$ particles, their mechanical strength was more enhanced than mechanical mixing or hydroxide precipitation methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.25-31
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• 2014

When the public key e and the composite number n=pq are disclosed but not the private key d in an asymmetric-key RSA, message decryption is carried out by obtaining ${\phi}(n)=(p-1)(q-1)=n+1-(p+q)$ and subsequently computing $d=e^{-1}(mod{\phi}(n))$. The most commonly used decryption algorithm is integer factorization of n/p=q or $a^2{\equiv}b^2$(mod n), a=(p+q)/2, b=(q-p)/2. But many of the RSA numbers remain unfactorable. This paper therefore applies baby-step giant-step discrete logarithm and $2^k$-ary modular exponentiation to directly obtain ${\phi}(n)$. The proposed algorithm performs a reverse baby-step and $2^k$-ary adult-step. As a results, it reduces the execution time of basic adult-step to $1/2^k$ times and the memory $m={\lceil}\sqrt{n}{\rceil}$ to l, $a^l$ > n, hence obtaining ${\phi}(n)$ by executing within l times.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.35-36
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• 2008

PTC thermistor are characterized by an increase in the electrical resistance with temperature. The PTC materials of middle Curie point were produced or that of high Curie point (above $200^{\circ}C$), it was determined that compositional modifications of $Pb^{2+}$ for $Ba^{2+}$ produce change sin the Curie point to higher temperature. PTC ceramic materials with the Curie point above $120^{\circ}C$ were prepared by adding $PbTiO_3$, PbO or $Pb_3O_4$ into $BaTiO_3$. Thereby, adding $Pb^{2+}$ into $BaTiO_3$-based PTC material to improve Tc was studied broadly, however, weal know that PbO was poisonous and prone to volatilize, then to pollute the circumstance and hurt to people, so we should dope other innocuous additives instead of lead to increase Tc of composite PTC material. In order to prepare lead-free $BaTiO_3$-based PTC with middle Curie point, the incorporation on $Bi_{1/2}K_{1/2}TiO_3$ into $BaTiO_3$-based ceramics was investigated on samples containing 0, 1, 2, 3, 4, and 50mol% of $Bi_{1/2}K_{1/2}TiO_3$. $Bi_{1/2}K_{1/2}TiO_3$ was compounded as standby material by conventional solid-state reaction technique. The starting materials were $Bi_2O_3$, $K_2CO_3$, $BaCO_3$ and $TiO_2$ powder, and using solid-state reaction method, too. The microstructures of samples were investigated by SEM, DSC, XRD and dielectric properties. Phase composition and lattice parameters were investigated by X-ray diffraction.

• Korean Journal of Clinical Pharmacy
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• v.26 no.3
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• pp.201-206
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• 2016

Objective: Direct current cardioversion for atrial fibrillation could be associated with the risk of thromboembolic events. Anticoagulation therapy with warfarin (INR 2.0-3.0) is recommended 3 weeks before and 4 weeks after cardioversion to reduce the risk of thromboembolism. This study evaluated warfarin therapy in pharmacist-managed anticoagulant services (ACS). Methods: This retrospective study was performed in 106 patients with atrial fibrillation from 2012 to 2013. The primary efficacy endpoint was the composite of stroke, transient ischemic attack, myocardial infarction, and cardiovascular death. The primary safety measure was major bleeding. To evaluate the peri-procedural effects of warfarin treatment, we studied whether target INR was maintained, as well as the maintenance period of the therapeutic range. Quality of treatment was measured by time in therapeutic range (TTR) by using the Rosendaal method. Results: There were no thromboembolic events, but TEE examination at time of cardioversion showed a left atrial thrombus in three patients (2.8%). Bleeding complications after cardioversion occurred in 2 patients (1.9%). The average INR value at the time of cardioversion was $2.59{\pm}0.8$, and was within the therapeutic range in 83 patients (78%). Analysis of the patients in whom the value was within the therapeutic range twice consecutively showed that the ratio of TTR was 80% and the therapeutic range was maintained in 67 patients (63%) for an average of 4.90 weeks prior to cardioversion. Similarly, 76 patients (72%) had a stable INR within the therapeutic range for an average of 5.70 weeks and a mean TTR of 83%. Conclusion: Pharmacists significantly contributed to appropriate warfarin treatment with close monitoring during cardioversion. Likewise, active pharmacist monitoring and systemic management should be considered to reduce thromboembolism and bleeding complications in the peri-cardioversion period.