• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.137-144
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• 2005

Silica in primary system combines with an alkali grammatical particle metal and forms the zeolite layer which is hindering the heat transfer on the surface of the cladding. Zeolite layer becomes the cause of the damage in this way. The problems of the NPP's primary system have been issued steadily by EPRI. Through a series of experiments of the laboratory scale, we confirmed the applicability of NF membrane for silica removal, as silica rejection rate of NF membrane is about $60\;{\sim}\;70\%$ and boron rejection rate is about $10\;{\sim}\;20\%$. We accomplished a site experiment about four NF membranes manufactured by FilmTec and Osmonics Inc. In experiment using 400L of SFP water, when operation pressure is $10kg_{f}/cm^2$, we confirmed that the silica rejection rate of NF90-2540 manufactured by FilmTec Inc. is about $98\%$, boron rejection rate is about $43\%$. The silica rejection rate of NF270-2540 is about $38\%$, boron rejection rate is about $3.5\%$. Afterward, through additional experiments, such as long term characteristic experiments, we are going to design a optimum NF membrane system for silica removal.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.247-252
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• 2015

ZSM-5 crystals grew on the surface of ${\alpha}$-SiC and ${\beta}$-SiC particles by hydrothermal synthesis method. SiC particles which were > $50{\mu}m$ of size were used, and oxide layer were developed on the surface of the particles to induce growth of ZSM-5 from the surface. Then, synthesis time and temperature condition were considered growing ZSM-5. In this study, oxide layer was formed on ${\beta}$-SiC at $900^{\circ}C$ in air, and it was controlled to grow ZSM-5 grew from the ${\beta}$-SiC surface with $150^{\circ}C$ synthesis condition. This is due to Si-O-Si or Si-O-Al bond, which is basic framework of ZSM-5 can be easily formed, from the silicon oxide film on the surface of ${\beta}$-SiC. When the synthesis temperature was $200^{\circ}C$, the size of ZSM-5 was increased, and it covered much area of the SiC surface with better crystal shapes with longer synthesis time.

• The Korean Journal of Zoology
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• v.38 no.4
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• pp.565-569
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• 1995

We have previoosly demonstrated that the RecA-like protein of Schizosaccharomyces pombe (S. pombe) is immunologically related to Escherichia coil (E. coil) RecA protein and that the cellular level of the protein is significantly increased by inhibitors of nucleotide pool-forming enzymes such as hydroxyurea (HU) and methotrexate (MTX) (lee and Park, 1994; lee et al., 1994). In this study, we report that the ribonudeotide redudase activity of S. pombe is inhibited by E. coil RecA antibody, as determined by thin layer chromatography using [5-$^3$H]CDP as a substrate. The relative activity of ribonucleotide reductase was dramatically inhibited by 100 mM of flu (26.4% reduction) in in vitro assay, compared to that of non-treated control. The ribonucleotide reductase activity was also inhibited by immunoprecipitation with E. coil RecA antibody (43.3% reduction). These results indicate that the strudure of S. pombe ribonucleotide reductase is in part similar to that of E. coil RecA protein.

• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.155-163
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• 2011

Carbon nanotubes (CNT) have been attracted much attention since they have been expected to be used in various areas by virtue of their outstanding physical, electrical, and chemical properties. In order to make full use of their prominent electric conductivity in some areas such as electron emission sources, device interconnects, and electrodes in energy storage devices, direct growth of CNT with vertical alignment is definitely beneficial issue because they can maintain mechanical stability and high conductivity at the interface between substrates. Here, we report direct growth of vertically aligned CNT (VCNT) on Cu foils using thermal chemical vapor deposition and characterize the field emission property of the VCNT. The VCNT's height was controlled by changing the growth temperature, growth time, and catalytic layer thickness. Optimum growth condition was found to be $800^{\circ}C$ for 20 min with acetylene and hydrogen mixtures on Fe catalytic layer of 1 nm thick. The diameter of VCNT grown was smaller than that of usual multi walled CNT. Based on the result of field emission characterization, we concluded that the VCNT on Cu foils can be useful in various potential applications where high conductivity through the interface between CNT and substrate is required.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.752-757
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• 2017

Analysis has been performed for the penetration of a long-rod into MMC/Ceramic layered armour system with several shot test and a series of simulations. Two types of MMC plate have been fabricated by a liquid pressing method; A356/45%vol.%SiCp with a uniform distribution of SiC particle and Al7075/45%vol.B4Cp with B4C particle. The mechanical properties were measured with the high-speed split Hopkins bar test, hardness test and compression test. The popular Simplified Johnson-Cook model was adopted to represent the material characteristics for FEM simulations. The performance of the MMC applied armour system has been made by comparing with the semi-infinite mild steel target using the depth of penetration(DOP). The results show that placing ceramic front layer provides a certain gain in protection, and that placing another ductile front layer provides a further gain. The application of MMC is found to be attractive.

• Journal of Chest Surgery
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• v.31 no.5
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• pp.531-535
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• 1998

In 1964, Abbott and Colleagues published the world's first heterotopic heart transplantation technique in the rat. Their method established circulation by end-to-end anastomoses of the graft's aorta and pulmonary artery to the recipient's abdominal aorta and Inferior Vena Cava(IVC), respectively. In 1966, Tomita et al altered Abbott's technique by employing end-to-side rather than end-to-end anastomoses, thus eliminating the hind leg paralysis that sometimes resulted from Abbott's technique. In order to prevent postsuture hemorrhage (since 7-0 silk suture was the finest available at that time), Tomita's aortic anastomosis was done with double up-and-down continuous suture technique. A single layer continuous anstomosis effected the pulmonary artery-IVC anastomosis. The availability of Nylon monofilament suture made it possible for Ono and Lindsey to use a single layer suture technique for the aortic end-to-side anastomosis in their modified rat heart transplantation. We observed survival time between control group and Immunosuppression(Cyclosporine administration, 10mg/Kg${\times}$4 times postoperatively) group after heterotopic heart transplantation in the rat model. The cyclosporine adminstration group survived longer than the control group, thus we concluded that cyclosporine was based on Immunosuppressive drugs.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.527-534
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• 1992

Raney nickel was used as catalyst in the hydrogen electrode for an alkaline fuel cell. The hydrogen electrode manufactured with the Raney nickel catalyst which was sintered at $700^{\circ}C$ was found to have the highest electrode performance. Using the Raney nickel powder of average particle size $90{\AA}$ for the electrode, the current density which had been measured was $450mA/cm^2$ at $80^{\circ}C$ using 6N KOH solution as an electrolyte. The effects of PTFE addition were investigated with CO-chemisorption, polarization curves and Tafel slope. CO-chemisorption had shown the optimum value when the Raney nickel was mixed with 5wt% of PTFE, but from the current density and Tafel slope at porous Raney nickel electrode, the appropriate value of PTFE addition was 10wt%. Recommendable Ni and Al portion for Raney nickel was 60 : 40 and loading amount was $0.25g/cm^2$. Also the influence of pressing pressure for manufacturing catalytic layer and for junction with gas diffusion layer was examined. The morphology of catalyst surface was investigated with SEM. The influence of reactivation time and heat-treatment temperature were also studied.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.590-600
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• 2021

This study compared the stand structure of Abies koreana forests between Mt. Jirisan and Mt. Hallasan by analyzing DBH distribution, stem vitality, crown structure, importance value, species diversity, and DCA. The data were acquired through the national long-term ecological research project conducted by the Ministry of Environment. In the comparison of DBH class distribution, the stem density of A. koreana with DBH < 20 cm was higher in Mt. Hallasan than that in Mt. Jirisan; however, the stem density of A. koreana with DBH > 20 cm was higher in Mt. Jirisan than that in Mt. Hallasan. For A. koreana stem vitality, the ratio of alive standing was higher in Mt. Jirisan (72.0%) than in Mt. Hallasan (60.7%), whereas the ratio of alive leaning was higher in Mt. Hallasan (10.2%) than in Mt. Jirisan (1.1%). A. koreana stand in Mt. Jirisan was a mature stand with four evenly developed and distinct layers, whereas the tree layer in Mt. Hallasan was less than 10 m and the stand had three layers without a subtree layer. Mt. Hallasan's importance value of A. koreana was 39.4% higher than Mt. Jirisan's importance value of 26.6%. The species diversity of the A. koreana community of Mt. Jirisan was 2.52 times higher than that of Mt. Hallasan, which was 1.58. DCA results revealed that the average distance between Mt. Jirisan and Mt. Hallasan was relatively distinguished, and the degree of scattering of species composition of Mt. Jirisan was relatively dense compared with that of Mt. Hallasan.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.659-662
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• 2018

We report the properties of infrared photodetectors based on two kinds of quantum dots(QDs): i) 2.0 ML InAs QDs by the Stranski-Krastanov growth mode(SK QDs) and ii) sub-monolayer QDs by $4{\times}[0.3ML/1nm\;In_{0.15}Ga_{0.85}As]$ deposition(SML QDs). The QD infrared photodetector(QDIP) structure of $n^+-n^-(QDs)-n^+$ is epitaxially grown on GaAs (100) wafers using molecular-beam epitaxy. Both the bottom and top contact GaAs layers are Si doped at $2{\times}10^{18}/cm^3$. The QD layers are grown with Si doping of $2{\times}10^{17}/cm^3$ and capped by an $In_{0.15}Ga_{0.85}As$ layer at $495^{\circ}C$. The photoluminescence peak(1.24 eV) of the SML QDIP is blue-shifted with respect to that (1.04 eV) of SK QDIPs, suggesting that the electron ground state of SML QDIP is higher than that of the SK QDIP. As a result, the photoresponse regime(${\sim}9-14{\mu}m$) of the SML QDIP is longer than that (${\sim}6-12{\mu}m$) of the SK QDIP. The dark current of the SML QDIP is two orders of magnitude smaller value than that of the SK QDIP because of the inserted $Al_{0.08}Ga_{0.92}As$ layer.

• Applied Biological Chemistry
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• v.20 no.2
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• pp.188-204
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• 1977

The studies on the saponins of Korean ginseng, Panax ginseng C.A. Meyer, were performed according to the cultivating locations, sampling seasons, plant parts, and growing stages. The changes in saponin content in the course of manufacturing Red ginseng and Ginseng extract were observed. In this paper, a new method for the determination of the total and the individual saponin glucosides was proposed and applied to the samples under study. The method employing Digital Densitorol DMU-33C (Toyo electric Co., Japan) followed the separation of the saponins by means of a preparative thin layer chromatography. The saponin contents and their fractional distribution were summarized as follows: 1. The average concentrations(% plant dry weight) of semi-purified saponins in the roots of Korean ginseng planted in the various locations were 5.0%(Keumsan), 6.0% (Kimpo), and 5.4% (Pocheon), respectively. 2. There were 3.3% saponins in White ginseng(Rhizome) and 12.7% saponins in Ginseng tail (Fibrous root). 3. Regarding the year of growth, the contents of saponins were 90.3mg (2-year-old ginseng), 254.4mg (3-year-old ginseng), 404.2mg (4-year-old ginseng). 999.6mg (5-year-old ginseng), and 1377.1mg (6-year-old ginseng) respectively, and the saponin factions containing panaxatriol as an aglycone increased. 4. Thin layer chromatography revealed that Red ginseng yielded many saponins which Shibata et al. designated as $ginsenoside-Rb_1$ (22.1%), $-Rb_2(15.4%)$, -Rc(12.6%), -Re (15.7%), and $-Rg_1$, (9.3%). 5. 29.9% of crude saponins were isolated from ethanolic extract of Panax ginseng fibrous root and their extraction yield was 94.2% of fibrous root saponin.