• Membrane Journal
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• v.17 no.1
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• pp.61-66
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• 2007

A zeolite membrane shows better thermal, mechanical and chemical stabilities than a polymer membrane. Water was separated from iso-propyl alcohol (IPA)/water mixtures by pervaporation using the NaY zeolite membrane synthesized in the laboratory. The effects of a mole fraction of IPA in the feed solution and an operating temperature were studied on the permeation flux behavior and the separation factor of water with respect to IPA. As a mole fraction of IPA increased, the water flux as well as the separation factor decreased. As the experimental temperature increased, the water permeation flux increased while the separation factor decreased. For IPA/water binary mixtures, the water flukes through the NaY zeolite membrane were observed to be $1.9{\times}10^2{\sim}3.5{\times}10^3\;g/m^2{\cdot}hr$ and the separation factors were found to be $7.0{\times}10^2{\sim}2.0{\times}10^4$.

• Membrane Journal
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• v.22 no.5
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• pp.359-368
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• 2012

For hybrid water treatment of high turbidity water, we used the hybrid module that was composed of photocatalyst packing between tubular membrane outside and module inside. Photocatalyst was PP (polypropylene) bead coated with $TiO_2$ powder by CVD (chemical vapor deposition) process. Water back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling for modified solution was prepared with humic acid and kaolin. Resistance of membrane fouling ($R_f$) decreased as humic acid concentration changed from 10 mg/L to 2 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L, which was the same with the previous results. Then, treatment efficiencies of turbidity and humic acid were above 98.9% and 88.7%, respectively. As results of treatment portions of UF, UF + $TiO_2$, and UF + $TiO_2$ + UV processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of humic acid by adsorption and photo-oxidation were 2.5% and 12.3%, respectively. Compared with the previous results, treatment portions of humic acid by adsorption and photo-oxidation were different depending on membrane material and pore size. As simplified the process, the membrane fouling resistance after 180 minutes' operation ($R_{f,180}$) increased and the final permeate flux decreased a little.

• Journal of Korea Foundry Society
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• v.23 no.3
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• pp.153-157
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• 2003

본 논문은 레오캐스팅용 AZ91 합금 슬러리를 제조하는 새로운 방법에 관한 것이다. 그 원리는 AZ91 합금 액상에서 Mn의 용해도차에 의해 생성되는 $Al_8(Mn,Fe)_5$ 정출물을 ${\alpha}-Mg$ 초정 생성을 위한 불균일 핵생성 자리로 사용하고자 하는 것이다. 제조된 슬러리의 미세조직 분석결과 $Al_8(Mn,Fe)_5$ 정출물이 ${\alpha}-Mg$ 내에 위치하고 있어, 이로부터 정출물이 효과적으로 불균일 핵생성 자리로 작용하고 있음을 알 수 있었다. 또한 Mn 함량의 증가는 $Al_8(Mn,Fe)_5$ 정출물 수를 증가시켜 고상분율이 일정할 때 슬러리 내 ${\alpha}-Mg$ 고상의 크기를 감소시키고 구형도를 향상시킨다. 이외에도 냉각속도 및 유지시간이 슬러리 미세조직에 미치는 영향에 대해서도 보고하였다.

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.98-105
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• 2013

The NaA zeolite particles were dispersed in a poly(vinyl alcohol) (PVA) matrix to prepare a composite membrane. The nano sized zeolite particles of NaA were synthesized in the laboratory and the mean size was approximately 60 nm. Pervaporation characteristics such as a permeation flux and a separation factor were investigated using the membrane as a function of the feed concentration from 0.01 to 0.05 mole fraction and the weight % of NaA particles between 0 wt% and 5 wt% in the membrane. Also, the micro sized particles of $5{\mu}m$ were dispersed in the membrane for a comparison purpose. When the ethanol concentration in the feed solution was 0.01 mole fraction, the flux of water significantly increased from $600g/m^2/hr$ to $2000g/m^2/hr$ as the content of the nano NaA particles in the membrane increased from 0 wt% to 5 wt%, while the NaA particles improved the separation factor from 1.5 to 7.9. When the flux of water through the membrane containing nano sized particles was roughly 15% increased compared to the micro sized particles, whereas the separation factor of water was found to be approximately 5% increased. It can be said that the role of the nano sized NaA particles is quite important since both the flux and the separation factor are strongly affected.

• Journal of Gastric Cancer
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• v.7 no.3
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• pp.167-173
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• 2007

Purpose: Mistletoe (Viscum album L.) extract is one of the most widely used agents in alternative cancer therapeutic regimens in Europe. This study was conducted to determine the effect of mistletoe extract on immune function in gastric cancer patients. Materials and Methods: Ten patients that had undergone a curative gastrectomy were enrolled in the prospective study. ABNOBAviscum $Q^{(R)}$ was injected subcutaneously three times a week from postoperative-day 7 to week 16 with an increasing dose. All of the patients simultaneously received chemotheraphy with mitomycin, oral 5-FU and a cisplatin regimen. The WBC count, differential count, lymphocyte/WBC ratio and the level of cytokines (IL-$1{\beta}$, IL-2, IL-6, IFN-$\gamma$, TNF-$\alpha$) were checked in the peripheral blood preoperatively, at postoperative week 8 and at postoperative week 16. Results: The WBC and neutrophil counts significantly decreased after treatment on week 8 and week 16 (P=0.001), but the total eosinophil count was slightly increased (P=0.15). The total lymphocyte count also decreased during treatment but the lymphocyte/WBC ratio was slightly increased without statistical significance (P=0.91). The cytokine levels did not significantly change during treatment. Conclusion: It is somewhat difficult to determine the direct effect of mistletoe therapy on immune function as the effect may be compromised by the concurrent chemotherapy. It can be assumed that the slightly increased lymphocyte/WBC ratio and eosinophil count may be a result of the immunomodulatory effect of the mistletoe extract.

• Korean Journal of Materials Research
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• v.7 no.6
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• pp.453-459
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• 1997

용탕단조법에 의해 제조된 Mg-9AI-2Zn 합금을 미세조직관찰, 미소경도측정, 인장시험 등을 행하여 시효거동과 기계적 성질을 조사하였다. 용탕에 가압을 한 결과 주조결함이 제거된 미세한 주조조직을 얻었으며 미세조직은 초정 $\alpha$(Mg 고용체), 과포화고용체 $\alpha$상 및 $\beta$(Mg$_{17}$AI$_{12}$)화합물의 3가지 상으로 구성되어 있었다. 16$0^{\circ}C$및 20$0^{\circ}C$에서 시효열처리한 결과 $\beta$석출물에 의한 피크 경도값이 나타났으며 피크경도에서의 석출물의 형태는 lamella 형태의 불연속 석출물이 대부분이었고 과시효에 따라 불연속석출물의 조대화와 함께 연속석출물의 분율이 증가하였다. 용탕단조방법에 의해 제조된 Mg-9AI-2Zn 합금의 인장특성은 인장강도 261.4MPa, 연산율 7.6%로서 상용 AZ 92 합금보다 인장강도 및 연신율에서 우수한 기계적 성질을 가졌는데 이는 Zn의 고용강화 및 용탕의 가압에 의한 효과였다.다.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.513-519
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• 1998

Zr-Si binary alloys containing 0.01 to O.lwt.%Si were prepared to investigate the effect of Si on the corrosion behavior of Zr. Corrosion test was performed in pure water at 36$0^{\circ}C$ under a pressure of 2660psi for 100days. The alloys containing 0.01 wt. % and 0.05wt. %Si had the black and uniform oxide film and didn't show the transition of corrosion rate. However. the alloys containing O.lwt.%Si had white oxide film and showed the trasition of corrosion rate at 70 days corrosion test. The weight gain increased with the increasing Si content from 0.01 to 0.1 wt.%. The variation of Si contents had no effect on changing the oxide structure but had significant effect on the electrical resistivity of oxide. The electrical resistivity decreased with increasing Si content. The fraction of precipitates in the Zr-Si binary alloys. identified as tetragonal $Zr_{3}$Si increased with increasing Si content. The increase of the volume fraction of precipitates is thought to be responsible for the increase of weight gain due to short circuit effect of precipitate.

• Analytical Science and Technology
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• v.35 no.6
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• pp.249-255
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• 2022

In this study, a new method for the analysis of high-purity nitrogen was developed. A gas chromatography-flame ionization detector (GC-FID) was used for purity analysis. Certified reference materials (CRMs) at a level of 3 µmol/mol of carbon monoxide (CO), carbon dioxide (CO₂), and methane (CH₄), which may exist in high-purity nitrogen, were prepared using the gravimetric method, and these CRMs were used for purity analysis. In this new method, ultra-high-purity and high-purity nitrogen were used as carrier gases. The impurities in high-purity nitrogen were quantitatively analyzed by comparing the differences in the area values of the GC chromatograms of the prepared CRMs. We purchased liquid nitrogen and three bottles of nitrogen gas, which were produced by three different manufacturers, using high-purity nitrogen. Furthermore, to validate the developed purity analysis method, the fraction of impurities in high-purity nitrogen was compared with the results of the typical purity analysis method. The comparison results were consistent within the expanded uncertainties (k = 2).

• Journal of the Korean Chemical Society
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• v.27 no.3
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• pp.167-177
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• 1983

The kinetics of 2-anthracenesulfonyl chloride in methanol-water, ethanol-water, acetone-water and acetonitrile-water has been studied by electroconductometric method. For media in which water has the same mole fraction, the rate was greater in protic solvent than in dipolar aprotic solvent and it was greater consistently in methanol-water than in ethanol-water over the whole range of solvent composition investigated, while the two rates in acetone-water and acetonitrile-water inverted at about 0.9 of mole fraction of water. Both m value, susceptibility of rate to the ionizing power and n value, solvent participation number in the transition state were much smaller in protic solvent. These values and the activation parameters show that solvolysis of 2-anthracenesulfonyl chloride proceeds by $ S_N2$ mechanism.

• Radiation Oncology Journal
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• v.18 no.3
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• pp.200-204
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• 2000

Purpose : We already reported the results that aqueous extract of Korean ginseng roots showed a marked cytotoxicity. In this study, we investigated whether combined ginseng product with X-irradiation increase the cytotoxicity of tumor cells than X-irradiation or not. Materials and Methods : Fifty gram of Korean ginseng powder mixed with 1 L of distilled water was extracted with reflux flask under condition of $100^{\circ}C$ for 5 hrs. This aquaous ginseng extract was filtered, centrifuged and then was freezed under condition of $-90^{\circ}C$ for 16-18 hrs. The freezing extract was dried with freeze drier, and then diluted. X-irradiation was given to tumor cells by 6 MeV linear accelerator. The cytotoxicity of ginseng in vitro was evaluated from its ability to reduce the clonogenecity of fibrosarcoma (FSa II) cells. In X-irradiation alone group, each 2, 4, 6 and 8 Gy was given to tumor cells. In X-irradiation with ginseng group, 0.2 mg/mL of ginseng extract was exposed to tumor cells for 1 hour before X-irradiation. Results : The yield for 50 g of ginseng extract which was treated with freezing drier was 3.13 g($6.3\%$). Cytotoxicity In vitro was measured as survival fraction which was judged from the curve, at ginseng concentration of 0.001, 0.01, 0.1 and 1 mg/mL were $0.89\pm0.04$, $0.86\pm0.06$, $0.73\pm0.01$ and $0.09\pm0.02$, respectively. Survival fraction at X-irradiation alone of 2, 4, 6 and 8 Gy were $0.81\pm0.07$, $0.42\pm0.08$, $0.15\pm0.02$, $0.03\pm0.01$, respectively. But, suwival fraction in combined group of X-irradiation and ginseng (0.2mg/ml) at each same radiation dose were $0.28\pm0.01$, $0.18\pm0.03$, $0.08\pm0.02$, $0.006\pm0.002$, respectively (p<0.05). Conclusion : The yield for ginseng extract which was treated with freezing drier was $6.3\%$. Cytotoxicty of Fsa 11 in combined ginseng with X-irradiation group was increased than that of X-irradition alone group, and its enhancing effect seemed to be added.