• 대한기계학회논문집 C: 기술과 교육
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• 제1권1호
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• pp.59-68
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• 2013

본 연구에서는 한외여과막과 역삼투압막으로 이루어진 해수담수화장치를 구성하였다. 해수를 취수하여 디스크필터와 한외여과막을 이용한 전처리설비를 통과시켜 생산한 전처리수의 $SDI_{15}$와 탁도를 측정하여 역삼투압해수담수설비에 적합함을 밝혔다. 역삼투압해수담수설비의 부산물인 브라인을 전처리수와 혼합하여 역삼투압해수담수설비의 입구농도를 변화시켰다. 농도 변화실험에서, 해수농도가 역삼투압해수담수설비의 성능에 끼치는 영향을 실험으로 구하였다. 염배제율, 회수율, 생산수의 수질은 입구농도에 따라 많은 변화가 있었으며, 에너지소비량도 입구농도에 거의 선형적으로 상승하는 것을 실험으로 구하였다.

• 한국대기환경학회지
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• 제18권2호
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• pp.161-170
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• 2002

Total(=wet+dry) atmospheric depositions were collected by filtration-sampling method at 17 sampling sites of the coal-fired power plant area from September 1999 to January 2000. The soluble and insoluble fractions of deposition were also measured to investigate a suitability of simplified collection method for a long-term monitoring of total deposition. In the study, the 50% of sampled soluble fractions showed the electric conductivity (E.C.) of below 50 $\mu$S/cm and the 42% of them showed the lower pH than 5.0. The monthly mean fluxes of water soluble ionic components; S $O_4$$^{2-}$, C $l^{[-10]}$ , N $O_3$$^{[-10]}$ , N $a^{+}$, N $H_4$$^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$ were 168.4 kg/k $m^2$.month, 100.5 kg/k $m^2$.month, 88.6kg/k $m^2$.month, 31.3kg/k $m^2$.month, 25.6 kg/k $m^2$.month, 13.3 kg/k $m^2$.month, 8.7 kg/k $m^2$.month, 43.1kg/k $m^2$.month, respectively. The mean ionic concentration of all sample(n=79) was 314 $\mu$eq/ι, with contributions of 24.2% and 23.0% by [nss-C $a^{2+}$] and [nss-S $O_4$$^{2-}$]. The ratio of [N $O_3$$^{[-10]}$ ]/[nss-S $O_4$$^{2-}$] and [N $H_4$-C $a^{2+}$] were found to be 0.52 and 0.68, respectively.espectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.150-150
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• 2010

Carbon nanotubes have drawn attention as one of the most promising emitter materials ever known not only due to their nanometer-scale radius of curvature at tip and extremely high aspect ratios but also due to their strong mechanical strength, excellent thermal conductivity, good chemical stability, etc. Some applications of CNTs as emitters, such as X-ray tubes and microwave amplifiers, require high current emission over a small emitter area. The field emission for high current density often damages CNT emitters by Joule heating, field evaporation, or electrostatic interaction. In order to endure the high current density emission, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects: highly crystalline CNT materials, low gas emission during electron emission in vacuum, optimal emitter distribution density, optimal aspect ratio of emitters, uniform emitter height, strong emitter adhesion onto a substrate, etc. We attempted a novel approach to fabricate CNT emitters to meet some of requirements described above, including highly crystalline CNT materials, low gas emission, and strong emitter adhesion. In this study, CNT emitters were fabricated by filtrating an aqueous suspension of highly crystalline thin multiwalled CNTs (Hanwha Nanotech Inc.) through a metal mesh. The metal mesh served as a support and fixture frame of CNT emitters. When 5 ml of the CNT suspension was engaged in filtration through a 400 mesh, the CNT layers were formed to be as thick as the mesh at the mesh openings. The CNT emitter sample of $1{\times}1\;cm^2$ in size was characteristic of the turn-on electrical field of 2.7 V/${\mu}m$ and the current density of 14.5 mA at 5.8 V/${\mu}m$ without noticeable deterioration of emitters. This study seems to provide a novel fabrication route to simply produce small-size CNT emitters for high current emission with reliability.

• Membrane and Water Treatment
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• 제9권4호
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• pp.279-284
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• 2018

Membrane biofouling is a critical operational problem that hinders the rapid commercialization of MBRs. Quorum quenching (QQ) has been investigated widely to control membrane biofouling and is accepted as a promising anti-fouling strategy. Various QQ strategies based on bacterial and enzymatic agents have been identified and applied successfully. Whereas, this study aimed to compare indigenously isolated QQ strain i.e., Enterobacter cloaca with well reported Rhodococcus sp. BH4. Both bacterial species were immobilized in polymeric beads and introduced to two different MBRs keeping the overall beads to volume ratio as 1%. Efficiencies of these strains were monitored in terms of prolonging the membrane filtration cycle of MBR, release of extra-cellular polymeric substances, membrane resistivity measurements and mineralization of signal molecules and permeate quality. Indigenous strain (Enterobacter cloaca) was added to $QQ-MBR_E$ while Rhodococcus sp. BH4 was introduced to $QQ-MBR_R$. QQ bacterial embedded beads showed enhanced filtration cycles up to 1.4 and 2.3 times for $QQ-MBR_E$ and $QQ-MBR_R$ respectively as compared to control MBR (C-MBR). Soluble EPS concentration of 52 mg/L was observed in C-MBR while significantly lower EPS concentration of 20 and 10 mg/L was witnessed in $QQ-MBR_E$ and $QQ-MBR_R$, respectively. Therefore, substantial reduction in biofouling showed the effectiveness of indigenous strain.

• Membrane and Water Treatment
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• 제10권2호
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• pp.113-120
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• 2019

To investigate surface properties and interception performances of the new modified PVDF membrane coated with Graphene Oxide (GO) and nano-$TiO_2$ (for short the modified membrane) via the interface polymerization method combined with the pumping suction filtration way, filtration experiments of the modified membrane on Humic Acid (HA) were conducted. Results showed that the contact angle (characterizing the hydrophilicity) of the modified membrane decreased from $80.6{\pm}1.8^{\circ}$ to $38.6{\pm}1.2^{\circ}$. The F element of PVDF membrane surface decreased from 60.91% to 17.79% after covered with GO and $TiO_2$. O/C element mass ratio has a fivefold increase, the percentage of O element on the modified membrane surface increased from 3.83 wt% to 20.87%. The modified membrane surface was packed with hydrophilic polar groups (like -COOH, -OH, C-O, C=O, N-H) and a functional hydrophilic GO-polyamide-$TiO_2$ composite configuration. This configuration provided a rigid network structure for the firm attachment of GO and $TiO_2$ on the surface of the membrane and for a higher flux as well. The total flux attenuation rate of the modified membrane decreased to 35.6% while 51.2% for the original one. The irreversible attenuation rate has dropped 71%. The static interception amount of HA on the modified membrane was $158.6mg/m^2$, a half of that of the original one ($295.0mg/m^2$). The flux recovery rate was increased by 50%. The interception rate of the modified membrane on HA increased by 12% approximately and its filtration cycle was 2-3 times of that of the original membrane.

• 대한핵의학회지
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• 제19권1호
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• pp.127-136
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• 1985

To evaluate change of serum $beta_2-microglobulin$ concentration$(s\beta_2-MG)$ and the usefulness of $s\beta_2-MG$ and $s\beta_2-MG/serum$ creatinine concentration(sCr) ratio in various renal diseases, $s\beta_2-MG$ and sCr were measured in 25 normal controls and 90 patients of various renal diseases(16 cases of glomerulonephritis, 12 cases of acute renal failure, 8 cases of chronic renal failure, 24 cases of nephrotic syndrome, 15 cases of tubulointerstitial diseases and 15 cases of lupus nephritis) using $Phadebas^\circledR$ $Beta_2-Micro$ Test kits. The results were as follows; 1) In normal control, the mean value of $s\beta_2-MG$ was $1.65{\pm}0.41mg/l$ and the mean value of $s\beta_2-MG/sCr$ ratio was $0.14{\pm}0.05$. 2) In various renal diseases, the mean value of $s\beta_2-MG$ was $6.74{\pm}5.47mg/l$. The mean value of $s\beta_2-MG/sCr$ ratio was $0.24{\pm}0.11$ and significantly elevated than that of normal control. (p<0.05) 3) The correlation between $s\beta_2-MG$ and sCr in glomerular and tubulointerstitial disease was log $s\beta_2-MG-0.90$ log sCr-0.48 and its correlation coefficient was 0.78(p<0.05). 4) In glomerular disease, the correlation between $s\beta_2-MG$ and sCr was log $s\beta_2-MG-0.89$ log sCr-0.46(r - 0.76) and in tubulointerstitial disease, it was log, $s\beta2-MG-0.95$ log sCr-0.59 (r-0.87). There was no significant difference between the two groups(p<0.05). 5) Among 32 cases of glomerular and tubulointerstitial disease patients, whose sCr was within normal range, 17 cases showed elevated $s\beta_2-MG$. The mean values of $s\beta_2-MG/sCr$ ratio in these patients was $0.30{\pm}0.14$ and significantly elevated than that of normal control(p<0.05). 6) In 15 cases of lupus nephritis, 12 cases showed elevated $s\beta_2-MG$ with normal sCr and 12 cases showed elevated $s\beta_2-MG/sCr$ ratio. With above results, it was found that the $s\beta_2MG$ can be used as an index of glomerular filtration rate as in the case of sCr and that $s\beta_2-MG/sCr$ ratio can be used as a tool in early detection of slightly decreased glomerular filtration rate and in detection of the renal disease of increased $\beta_2-MG$ production.

• 상하수도학회지
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• 제19권1호
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• pp.78-91
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• 2005

Performance limiting factors (PLFs) derived from 161 drinking water treatment plants (DWTPs), assessed by International Technical Diagnosis & Assistance Center, were analyzed and evaluated in more detail in this study. In order to conduct study, 161 DWTPs were divided into five categories depending on their capacity, and into twelve groups according to processes and facilities. From the results of analysis, PLFs and their distribution ratio derived from each category were significantly different. Filtration was the most important performance limiting process in all DWTPs of five categories, and the PLFs in filtration were backwashing velocity, media configuration, bed depth, and formation of mud-ball. The PLFs in coagulation-flocculation process were found out to be coagulant dosage, mixing speed, mechanical problems, and others in the order of frequency of occurrence. Also, insufficient disinfection ability that is resulted from insufficient hydraulic detention time and improper chlorine dose and injection point, is the most significant among PLFs in a clear well. In the case of sedimentation, inappropriate baffle structure and excessive upward velocity were PLFs. In addition, the results showed that high turbid water and low alkalinity in a rainy season, ferric and manganese ions, and ammonia nitrogen have been contributed significantly on the performance of DWTPs.

• International Journal of Industrial Entomology and Biomaterials
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• 제6권2호
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• pp.151-155
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• 2003

Using gel filtration chromatography, high molecular silk fibroin with high purity was obtained and silk flbroin microsphere particles (SFMP) could be simply made by spray dryer method. Also, some of the physicochemical properties of SFMP and morphology were investigated. The average molecular weight of pure silk fibroin protein dissolved in calcium chloride is about 61,500g/㏖ as measured by gel permeation chromatography. SFMP was spherical in shape, and particles, sized average of 2 ${\pm}$ 10 ${\mu}$, were observed by SEM and particle analyzer, respectively. Obtaining microspheres particles by spray dryer method accelerated the transition from the random coil to the $\beta$-sheet structure during spray dryer treatment. It was identified by the basic fourier transform infrared spectroscopy of SFMP. The swelling ratio of SFMP is majorly dependent on the pH of the solution, not on the occurred gelation. The characteristic structure, which might be applicable to immobilization of drugs is superior to other matrix materials for the use of biomaterials with skin affinity.

• Advances in environmental research
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• 제7권1호
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• pp.39-52
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• 2018

Direct membrane filtration (DMF) of wastewater has many advantages over conventional biological wastewater treatment processes. DMF is not only compact, but potentially energy efficient due to the lack of biological aeration. It also produces more biosolids that can be used to produce methane gas through anaerobic digestion. Most of ammoniacal nitrogen in wastewater is preserved in effluent and is used as fertilizer when effluent is recycled for irrigation. In this study, a technical feasibility of DMF was explored. Organic and nitrogen removal efficiencies were compared between DMF and membrane bioreactor (MBR). Despite the extremely high F/V ratio, e.g., $14.4kg\;COD/m^3/d$, DMF provided very high COD removal efficiencies at ~93%. Soluble microbial products (SMP) and extracellular polymeric substances (EPS) were less in DMF sludge, but membrane fouling rate was far greater than in MBR. The diversity of microbial community in DMF appeared very narrow based on the morphological observation using optical microscope. On the contrary, highly diverse microbial community was observed in the MBR. Microorganisms tended to form jelly globs and attach on reactor wall in DMF. FT-IR study revealed that the biological globs were structurally supported by feather-like materials made of secondary amines. Confocal laser scanning microscopy (CLSM) study showed microorganisms mainly resided on the external surface of microbial globs rather than the internal spaces.

• Journal of Pharmaceutical Investigation
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• 제14권2호
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• pp.92-103
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• 1984

The action of debrisoquine on renal function in rabbits was studied. 1. When debrisoquine was given into ear vein, it did not affect on renal functin with smaller doses of 0.1 or 0.3mg/kg, while with higher dose of 1.0mg/kg it elicited the significant decrease of urine flow, renal plasma flow and glomerular filtration rate, and the increase of filtration fraction, and at the same time sodium excreted in urine, FENa (fractional excretion of sodium) and osmolar clearance were significantly decreased, and then it exhibited the increase of $K^+/Na^+$ ratio and no changes of $T^cH_2O$. 2. Debrisoquine (1.0mg/kg), when injected repeatedly into a vein, produced a more marked decrease of urine flow. 3. Debrisoquine induced-antidiuretic action was not affected by pretreatment with phentolamine (2mg/kg, i.v.), alpha-sympathetic blocking agent. 4. Debrisoquine given intracerebroventricularly did not produce a significant change on renal function in dose of 0.1mg/kg. These results suggest that debrisoquine produce the antidiuretic effect in rabbit, and the mechanism of its action is due to dual actions that are the decrease of hemodynamic effect and the facilitation of reabsorption of sodium in renal tubules.