• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.303-303
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• 2008

$LiMn_2O_4$는 출력특성이 좋고 가격이 저렴하지만 전해액 중에서 $Mn^{2+}$이 용출되어 나오는 것과 반복적인 충방전시 구조가 파괴되는 단점이 있어 이것을 보완하고자 $FePO_4\cdot2H_2O$를 $LiMn_2O_4$의 표면에 코팅하였다, $LiMn_2O_4$를 모재로, $FePO_4\cdot2H_2O$를 코팅재로 사용하여 $FePO_4\cdot2H_2O$의 코팅량 변화와, 열처리 온도변화에 따른 물성 변화를살펴보았다, LiOH 와 $MnO_2$의 혼합물을 $1000^{\circ}C$ 에서 소성하여 $LiMn_2O_4$를 합성하고, Fe$(NO_3)_3$ 수용액과 $NH_4H_2PO_4$ 수용액을 혼합하여 $FePO_4\cdot2H_2O$를 제조하였다, $LiMn_2O_4$에 $FePO_4\cdot2H_2O$를 1wt%, 2wt%, 3wt% 비율로 ball milling 을 통해 코팅한 후, 온도를 변화시키면서 열처리 하였다. 코팅한 물질을 XRD를 통해 구조를 분석하고 SEM을 이용하여 형상을 관찰하였다. 또한 고온에서의 $Mn^{2+}$의 용출량을 ICP로 측정하고 half-cell을 만들어 충방전 test를 통해 충방전 특성을 조사하였다. 아울러, 코팅량과 열처리 온도 등 합성변수들이 소재특성 및 전기화학적 특성에 미치는 영향을 조사하였다.

• YAKHAK HOEJI
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• v.53 no.4
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• pp.228-234
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• 2009

Topoisomerase I (Topo I) participates in the DNA replication, transcription, and repair. Binding of Topo I inhibitor to the Topo I-DNA cleavage complex forms stabilized ternary complex which blocks DNA religation and ultimately causes cell death. Camptothecin (CPT) and its derivatives have been among the most effective anticancer drugs by inhibition of topo I. However, efforts to synthesize non-CPT drugs have been actively going on because the CPT derivatives have several limitations such as poor solubility, short half-life, and side effects. As an indenoisoquinoline, NSC314622 is not as potent as CPT, but its chemical stability and slower reversibility of the cleavage complex made it a good lead compound. Recently, a series of indenoisoquinoline analogues were synthesized with substituted dimethoxy or methylenedioxy on the aromatic ring and alkylamino on the lactam nitrogen. Some of them showed quite good Topo I inhibitory activity. Using the computer docking program, Surflex-Dock, indenoisoquinoline analogues were docked into the human Topo I-DNA cleavable complex. The docking results showed that the compounds with activity better than NSC314622 intercalated between the -1 and +1 base pairs at the cleavage site, but those with little or no activities did not appear to intercalate. These results could be useful to design new Topo I inhibitors improved than CPT.

• Korean Journal of Plant Resources
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• v.28 no.6
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• pp.727-733
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• 2015

Although Sophorae Flos (SF) has been reported to exert an anti-cancer activity, molecular targets and mechanisms associated with anti-cancer activity of SF have been unclear. Because cyclin D1 has been regarded as an important regulator in the cell proliferation, we focused cyclin D1 and investigated the effect of SF on the cyclin D1 regulation in light of elucidating the molecular mechanism for SF’s anti-cancer activity. The treatment of SF decreased cellular accumulation of cyclin D1 protein. However, SF did not change the level of cyclin D1 mRNA. Inhibition of proteasomal degradation by MG132 attenuated SF-mediated cyclin D1 downregulation and the half-life of cyclin D1 was decreased in the cells treated with SF. In addition, a point mutation of threonine-286 to alanine attenuated SF-mediated cyclin D1 downregulation. Inhibition of ERK1/2 by a selective inhibitor, PD98059 suppressed cyclin D1 downregulation by SF. From these results, we suggest that SF-mediated cyclin D1 downregulation may result from proteasomal degradation through its threonine-286 phosphorylation via ERK1/2. SF-induced proteasomal degradation of cyclin D1 might inhibit proliferation in human colorectal cancer cells. The current study provides information on molecular events for an anti-cancer activity of SF

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3567-3572
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• 2010

Black pine barks from the southern region of Korea were extracted using pressurized hot water and the water soluble extracts were then separated in a stepwise fashion using a variety of solvents, column chromatography (CC), thin layer chromatography (TLC), and high pressure liquid chromatography (HPLC). The antioxidant activities of each fraction and the active compounds were determined based on the radical scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH), reductive potential of ferric ion, and total phenol contents. A DPPH test showed that the half maximal effective concentration ($EC_{50}$ value : $6.59{\pm}0.31\;{\mu}g/mL$) of the ethyl acetate fraction (ca. 0.67%) was almost the same as that of the control compounds and inversely proportional to the value of the total phenol contents. The cell viability of the water extracts was confirmed by methyl thiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) with enzyme linked immune sorbent assay (ELISA). Catechin, epicatechin, quercetin and ferulic acid were isolated from the ethyl acetate fraction as active compounds and identified by nuclear magnetic resonance. The antioxidant activity as value of DPPH of each of the separated compounds was lower than the ethyl acetate fraction, and ferulic acid was the lowest among these compounds.

• Journal of Periodontal and Implant Science
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• v.28 no.3
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• pp.431-451
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• 1998

4 beagle dogs aged over one and half years and weighed 15 to 16 Kg were utilized in this study. Experimental dehiscent defects were made in the mandibular edentulous area after removal of lower premolar. e-PTFE membrane resorbable membrane, and PDGF-BB-loaded resorbable membrane were covered at the dehiscent defects around the dental implants respectively. Animal was sacrificed at 1, 2, 3 months respectively. Non-decalicifed specimens were made and mutiple-stained for light microscopic study. The results were as follows: 1. Dehiscent defects around the implant installed in the beagle dog were an excellent defect model for studying guided bone regeneration. 2. Fibroblasts penetrated into expanded-PTFE membrane was observed and inflammatory cell infiltration was also observed around the membrane. 3. Resorbable membrane was degradaded and resorbed at 1 month after application to the dehiscent defect. Though multinucleated giant cells were observed adjacent to the membrane, that had no reverse effect on the boe regeneration. 4. PDGF-BB-Ioaded resorbable membrane was same capability as the resorbable membrane and e-PTFE membrane in the guided bone regeneration. 5. PDGF-BB-Ioaded resorbable membrane-applied site was better than resorbable membrane-applied site in the speed and maturity of bone formation. Within the above results, it was suggested that PDGF-BB-Ioaded resorbable membrane might have same bone regeneration capacity as nonresorbable membrane in the dehisced implant of the beagle dog and potentiality to use in human subjects.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.644-648
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• 2004

In the present study were examined numerically and experimentally the off-design performance characteristics on an axisymmetric plug nozzle with variable throat area. In this nozzle concept, its throat area can be changed by translating the plug into the axial direction. First, a mixed-expansion plug nozzle, in which two expansion parts are arranged both inside and outside, was designed by means of the method of characteristics. Second, the CFD analysis was verified by the cold-flow wind tunnel test. Third, its performance characteristics were evaluated over a wide range of pressure ratio from half to double throat area through the design point, using the CFD code verified by the wind tunnel tests. It was made clear from the study that not so critical thrust efficiency losses were found and the maximum thrust efficiency loss was at most approximately 5 % under off-design conditions without external flow. This result shows that a plug nozzle can give the altitude compensation even under off-design geometry operations. However, shock waves were observed in the inner expansion part under the doubled throat area operation and thus some thermal problems may be caused on the plug surface. Furthermore, collapse of cell structure on the plug surface was observed with external flow (around Mach number 2.0) as it became lower pressure ratio below the design point and the fact may result in big efficiency loss regardless of geometrical configuration.

• Journal of Pharmacopuncture
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• v.3 no.2
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• pp.1-25
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• 2000

We were trying to study the validity of Puffer fish's poison(Tetrodotoxin- TTX) to make a traditional Korean Medical treatment. The following conclusions were made after literary studies. 1. The first record of the puffer fish dates back 2000 years ago in the Chinese text Book of Mountain and Sea and other texts from the similar period. 2. Puffer fish's poison IS known as tetrodotoxin which is an amino perhydroquinazoline compound. It has a chemical formula of $C_{11}H_{17}N_3O_8$ in the hemiacetal structure and has the molecular weight of 319. 3. Tetrodotoxin (TTX) plays a role as potent neurotransmitter blocker by blocking the $Na^+$ -gate channel which hinders the influx of $Na^+$ ion into the cell. 4. Symptoms of the puffer fish poisoning ranges from blunted sense in the lips and tongue, occasional vomiting in the first degree to sudden descending of the blood pressure, apnea, and other critical conditions in the fourth degree. Intoxication of the puffer fish poison progresses at a rapid pace as death may occur after an hour and half up to eight hours in maximum. Typical death occurs after four to six hours. 5. Ways to treat the puffer fish poisoning include gastric irrigation, induce vomiting, purgation, intravenous fluid injection, and correcting electrolytic imbalance and acidosis. In cases of dyspnea, apply oxygen inhalation and conduct artificial respiration. 6. Tetrodotoxin (TTX) may be applied in treating brain disorders, ocular pain, excess pain in the large intestine and ileum, and relieving tension of the skeletal museles, neuralgia, rheumatism, arthritis, and etc. 7. In terms of Oriental medicine, the puffer fish poison has characteristics of sweet, warm, and poisonous. It's known efficacies are to tonify weakness, dispel damp, benefit the lower back, relieve hemorrhoid, kills parasites, remove edema, and so forth. And the puffer fish eggs processed with ginger are said to be effective against tuberculosis and lung cancer, thus, it's validity must be investigated and further research should be followed.

• Transactions of the Korean hydrogen and new energy society
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• v.11 no.4
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• pp.189-202
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• 2000

$AB_2$ type Zr-based Laves phases alloys have been studied for potential application as a negative electrode in a Ni-MH battery. The $AB_2$-type electrodes have a much higher energy density than $AB_5$-type electrodes per weight, however they have some disadvantages such as poor activation behavior and cycle life etc. Nonetheless, the $AB_2$-type electrodes have been studied very extensively due to their high energy density. In this study, in order to develop the cycle life, the Mn of $AB_2$ alloy composition was substituted partially by Mo. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The alloy powder was used below 200-325 mesh for experiments. The structures and phases of the alloys were analyzed by XRD, SEM and EDS, and measured the curve of a pressure-composition isotherms. The electrodes were prepared by cold pressing of the copper-coated(25 wt%) alloy powders, and tested by a half cell. The results are summarized as follows. The cycle life was improved with the increase of Mo amount in $Zr_{1-x}Ti_xV_{0.4}Ni_{1.2}Mn_{0.4}Mo_y$(x=0.3, 0.4) and the activation was faster, whereas the discharge capacity decreased.

• Journal of the Korea Institute of Building Construction
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• v.14 no.5
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• pp.397-405
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• 2014

There are many literatures reporting that the service life of re-bars in concrete structures is reduced in the oceanic environment due to chloride attack. To solve this problem, this study used geo-polymer as a mix material for concrete to increase its resistance to salt damage, and the external voltage method, one of the electric methods, is was applied to evaluate the likelihood of re-bars in the oceanic structure being exposed to the extreme salt environment. The items evaluated include the natural potential of re-bars and the corrosion rate. The results of the tests showed that in all of the salt environmental conditions (submerged zone, tidal zone, and crack), the tested materials were remarkably effective compared with ordinary concrete. The corrosion protective property was found not only in the evaluation of the natural potential but also in the evaluation of the corrosion rate, suggesting that the external voltage method can be used stably for geo-polymer RC structures in an extreme salt environment.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.2
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• pp.166-171
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• 2007

GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, $GABA_{A}-receptor$ that allows chloride to pass through a ligand gated ion channel and $GABA_{B}-receptor$ that uses G-proteins for signaling. The $GABA_{A}$-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate $GABA_{A}$-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with $^{11}C-FMZ$, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, $^{18}F-fluoroflumazenil$ (FFMZ) has been developed to overcome $^{11}C's$ short half-life. $^{18}F-FFMZ$ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using $^{11}C-FMZ$ PET instead of $^{18}F-FDG$ PET, restrict the foci better and may also help find lesions better than high resolution MR. $GABA_{A}$ receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, $GAB_{A}$ imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.